Ground improvements

Road and pavement construction require huge volumes of borrowed soils in addition to the foundation soils. Unfortunately, not all soils are suitable for construction purposes. Soil stabilization is a fundamental technique used to enhance the engineering properties of weak ground/soil to meet the demands of large infrastructure projects, such as roads. It is in this regard that this study investigates the strength development, durability, and effectiveness of cement and quarry dust as stabilizers to enhance the geotechnical properties of a weak tropical clay soil. Cement was added in the range of 0% to 10% while quarry dust was used to partially replace soil in the range of 0% to 50%. The results show significant improvements in the Atterberg limits and strength properties of the tropical clay. The liquid limit reduced from 43.2% to 25.1% while the plasticity index reduced from 17.6% to 10.2% at 50% quarry dust and 10% cement content. Similarly, the maximum dry unit weight increased from 17.4 kN/m 3 to 21.3 kN/m 3 while the optimum moisture content decreased from 17.1% to 12.9%. The maximum soaked CBR value was 172%, representing a 1497% enhancement over untreated soil. Also, the maximum unconfined compressive strength (UCS) reached 2566 kN/m 2 at 28 days of curing, representing a 1793.73% increase when compared to the untreated soil. Cement content was found to be the predominant factor influencing strength development. The study shows that cement-quarry dust blends compacted at high energy can be adopted in sustainable road construction.

Welcome to the 8 th volume and issue number 1 of the ESTEEM Academic Journal UiTM (Pulau Pinang): a peer-refereed academic journal devoted to all engineering disciplines. This issue of journal sees a new Chief Editor and marks the journal's first electronic publication. Using the e-journal inauguration as an occasion, I would like to thank many people who created the opportunity for this e-journal to be born and who made it happen. First and foremost, I would like to extend my sincere appreciation and utmost gratitude to Associate

Consolidation grouting has long been widely applied in tunnels and dam foundations constructed by the State Hydraulic Works (DSİ). In water tunnels, the practice typically involves first filling the gap between the tunnel lining and the surrounding rock with contact grouting, followed by consolidation grouting at specified depths. The primary objectives are to reduce soil permeability and to improve the properties of the rock mass affected by excavation. Similarly, in concrete dam foundations, consolidation grouting is extensively used to increase the deformation modulus of the foundation, reduce differential settlements, prevent piping, and improve overall impermeability.
This study examines the necessity and effectiveness of consolidation grouting in tunnels and dam foundations under varying geological and structural conditions. For tunnels, consolidation grouting applied within a range of (D)+2 m to D/2 from the tunnel diameter will be discussed, particularly in conjunction with the widespread use of wet-mix shotcrete over the past four decades. The benefits of grouting in long tunnels with thick overburden, made possible by advances in TBM technology, are also evaluated. In dam foundations, attention is given to consolidation grouting depths, typically determined by the stress bulb induced by the dam load, while considering the effects of loosening zones created by excavation. Furthermore, the contribution of grouting to the deformation modulus is assessed with respect to soil type and the characteristics of fracture fillings.
Through case studies from both Turkey and international practice, this paper discusses how consolidation grouting depths in dam foundations should be determined, while also evaluating the costs and benefits of applications in both tunnels and dams.

The installation of a vertical drains system beneath the embankment results in enhanced soil consolidation in soft soil. This article explores the behaviour of soft soil stabilized with prefabricated vertical drains (PVDs) beneath embankments through finite element analysis. A multi-drain analysis, which varied the smear effect permeability ratio using both equivalent and plane strain models, was performed. Back-calculation of the permeability ratio of the smear effect is employed to adjust the model parameters. The analytical formulation employed the Cam-clay concept in combination with the smear effects. The study revealed that PVDs installation in the soft soil beneath the embankment increased the settlement rate and improved pore water pressure dissipation. Accurate prediction requires the estimation of the equivalent horizontal permeability using appropriate values of the smear effect permeability ratio. Incorporating the smear effect into the numerical analysis of vertical drains improved prediction accuracy. The article proposes a new approach for estimating the smear effect permeability ratio for soft soil stabilized with PVDs.

The construction industry is increasingly pressured to adopt sustainable practices that reduce environmental impact while ensuring structural integrity. This study investigates the comparative performance and sustainability of micropiles constructed with fly ash-enhanced grout mixtures (MFA) and conventional micropiles (MC). Fly ash, an industrial by-product is incorporated into the grout mixture to improve sustainability and enhance soil-structural stability. Comprehensive site investigations and numerical simulations were conducted to evaluate critical performance metrics, including Factor of Safety (FoS), deformation, settlement, and strain distribution, during pre-and post-construction phases. The results demonstrate that MFA systems exhibit superior performance, characterized by a higher FoS reaching ~3.0, reduced deformation (less than 3.0 m), and minimized settlement (maximum of-4.2 m compared to-14.6 m in MC). These findings indicate that MFA delivers structural benefits and contributes to sustainability by utilizing waste materials. The study underscores the potential of MFA as a viable alternative to traditional micropile systems, offering significant environmental and performance advantages. Further research is recommended to assess MFA systems' long-term performance and scalability in diverse geotechnical applications.

Foundations bearing on uncompacted coarse-grained soil deposits (e.g. aeolian fine sands) can experience excessive settlements under monotonic and cyclic loading conditions. Straightforward strategies for improving their geomechanical behaviour include mass replacement of the uniform fine sand with high-quality soil (typically coarser sand-with-gravel (S-G) material), along with including geosynthetic reinforcement layers, although this approach may prove uneconomical in practice. The present study advocates an alternative approach employing geogrid-reinforced thin dense S-G layers incorporated at discrete depths within the backfilled fine-sand deposit. A comprehensive programme of 1 g testing was performed to investigate the relative performances of fine sand beds incorporating geogrid layers, unreinforced thin dense S-G layers and geogrid-reinforced thin dense S-G layers compared to the plain (fully unreinforced) fine sand bed. A 150-mm dia. footing bearing on the surface of the sand beds was subjected to a combination of static loading followed by 2000 load cycles of different intensities. The experimental results confirmed that compared to the unreinforced/ geogrid-reinforced sand beds, the sand beds with geogrid-reinforced dense S-G layers demonstrated superior performance in terms of limiting the cumulative footing settlement. The demonstrated concept could be of practical use in the economic construction of reinforced soil walls, reinforced foundation beds, and so on.

The evaluation of axial capacity of jet grouted soil cement columns in soft soil is a complicated issue because it depends according to the number of factors such as, soil type, influence mixture between soil and grouting materials, nozzle jet energy, jet grouting and water flow rate, rotation and lifting speed. These parameters related to the type of jet grouting methods (single, double and triple system). Most methods of design the bearing capacity of the jet-grouting column based on experience. Therefore, some designer calculates the bearing capacity of the jet grouting column based on jet grout section capacity. In this paper, different theoretical methods have been used to estimate of the jet grouting soil-cement capacity, such as Poulos and Davis, 1980 methods and then their comparison with the pile load test calculations based on the quick pile load test as presented in ASTM-D1143-07. Therefore, the study describes a prototype test single and group jet grout soil-cement models of arrangement (1 1, 1 2 and 2×2) for total length to diameter ratios (L/D) is 13.33 and clear spacing three times of diameter has been constructed in soft clayey soils in the right bank of the Euphrates River, at Al-Nasiriyah city. As a result, the theoretical method for estimation the bearing capacity gives unfaithful values for the single and group jet grout column compared to the load-settlement calculations obtained from field pile load test data. On the other hand, the Hansen's 90% and Butler and Hoy's given closer results to each other and may be considered faithful interpretation methods to compute the bearing capacity of single and group jet grouting columns.

The application of prefabricated vertical drains (PVDs) in the road embankment construction has been successfully performed in many projects throughout the country. The simulation of finite element method (FEM) can assist engineers in modelling very complex structures and foundations. This paper presents a plane-strain numerical analysis that was performed to verify the effectiveness of the model embankment stabilised with PVD using Plaxis 2D version 8. This study employed the smear effect of permeability ratio (kr) of 3 in the PVD modelling. The data of settlement and pore water pressure in the left and right sides of road embankment were monitored for 177 days, then the data were collected and compared by a numerical simulation. The coefficient of determination (R 2) was used to assess the performance of the comparative analysis. The results of numerical simulation on settlement and pore water pressure obtained a coefficient of determination of greater than 0.9 which has reached a good agreement with those of the field measurement. On other the hand, there was no significant difference in the performance between both sides of the embankment. The smear effect parameter (kr = 3) is recommended for PVD designs and can provide accurate FEM prediction.

Results from laboratory model tests performed on circular footing are presented in this paper to understand the performance of geocell reinforced expansive soil. Naturally occurring expansive soil was used in this study as subsoil. Geocells of chevron pattern fabricated from geotextile made up of polypropylene were used to reinforce the soil bed. The parameters studied in this testing program were the placement depth of the geocell mattress, pocket size of geocell and the height of geocell mattress. Contrary to other researchers; the improvement in the performance of reinforced bed is evaluated at a settlement level equal to the failure settlement of unreinforced soil bed. The performance of reinforced bed is evaluated through two non-dimensional factors viz. bearing capacity improvement factor (If) and settlement reduction factor (PRS%). Test results indicated that with the introduction of geocell as reinforcement, a substantial improvement in bearing capacity and decrease in footing settlement can be achieved. Bearing capacity of reinforced bed increases by more than 200% and 81% reduction in footing settlement was achieved by using geocell mattress of optimal dimensions and placing it just below the footing base.

Deep Soil Mix (DSM) is a proven method of ground improvement for deeper underlying soft soil layers which are otherwise impractical to reach using conventional shallow soil stabilization and replacement methods. The predominant binder materials used are Ordinary Portland cement (OPC) and Lime (CaO) but negative effects to the environment from manufacture and increasing construction cost have prompted research into alternative materials. This review identifies pozzolans and filler materials as possible supplements or partial substitutes for better results. The DSM method and binder reaction processes during treated soil strength development are outlined and effectiveness of different pozzolans (Fly Ash, Silica Fume, Ground Granulated Blast Furnace Slag, Rice Husk Ash, Kaolin, and Metakaolin) and filler materials (e.g. fine sand) discussed together with their influence factors. With many pozzolans, a clear optimum dosage is observed where improved strength peaks. Aluminosilicate pozzolans perform better over siliceous pozzolans with Metakaolin (MK) identified as the most effective pozzolan for enhancing compressive strength. Up to date research results on these materials are compiled. MK blended cements are readily available and can be readily applied for initial field tests. Treated soil strength may be regulated with addition of filler materials to further reduce reliance on cement.

The effect of Cyclic loading on the foundation behaviour of many engineering structures presents more important and related to many problems in geotechnical engineering, Especially when construction on soft ground area which represent one of the major concerns in geotechnical engineering. This paper is conducted to investigate the influence of using several improving techniques as (fly ash, Geo-grid, fly ash and Geo-grid) on the behavior of soft clayey soil subjected to cyclic loading. A total of twenty four models have been tested which consists of a wide domain of boundary conditions, such as untreated model, Geo-grid reinforced models, fly ash treated models and models treated with fly ash incorporated with Geo-grid were conducted by varying parameters such as, footing elevations, test velocity and number of geogrid layers. The analysis demonstrates that the settlement behaviour of footing resting on treated models with fly ash and two Geogrid layers perform better than other improving techniques. Also observed there was an increase in settlement, which corresponds to the increase in test velocity from 6 to 9 mm/sec. Furthermore, it was conducted that the more depth of footing the soil settlement decreases. In general, when other factors remaining constant, the bearing capacity of soil goes on increasing when the depth increased.

In civil engineering, alternative materials showed rapid progress. Asphalt derived from Buton Island in Indonesia, also known as Asbuton, was located in the limestone bedrock. A large deposit of Asbuton could guarantee the supply of alternative construction materials. In that regard, Asbuton performance as an alternative material to several subjects needs to be analyzed. Therefore, this study was conducted to analyze Asbuton's behavior as a filler in a floating column model as a soft soil improvement concept. Asbuton added to sand and gravel mixture as filler and waterglass as a binder. CBR samples were tested to acquire the optimum composition with varied curing days namely 0, 3, and 7 days, following ASTM D-1883, followed by a compressive column model test which was based on ASTM D-2166. Finally, the column applied to the soft soil layer to be tested in a loading test, and the results are then compared for each composition. The results showed that the granular material's composition including Asbuton, the waterglass content, and the curing period significantly affect the engineering properties of the artificial column. The results revealed that the granular column with Asbuton with the addition of waterglass could increase soil's load capacity and reduce the settlement of soft soils.

Sand is a major component of soils. It is widely used in manufacturing and construction. In geomechanics, one characterizes sand according to various aims. This paper investigates, for local sands, the effect of grain size and granular distribution on the mechanical behavior in terms of strength and stress-strain relationship. For this purpose, dune sands of the great Occidental Erg, from Algeria, are analyzed, according to the Mohr-Coulomb criterion. The study uses three kinds of sands. Every kind is divided into three sizes classes. Then, the experimental program conducts a set of direct shear tests, under various vertical stresses, using the small shear box (60 × 60 mm). The results show that the particle size and distribution have a direct effect on the mechanical behavior of the dune sand. Then, the dominant size class governs the natural sand behavior. Moreover, the peak shear strength increases as particle size increases. This indicates that there is an increase in peak friction angle with the increase of particles size and the sands consider as a purely cohesionless material. In addition, the experimental analysis shows that density and confinement stress is not sufficient to interpret the mechanical behavior. Indeed, mineralogy and surface state can influence the shear strength. These conclusions lead to the relevance of the sand genesis and the importance of the local materials thematic.

Expansive soils like clays undergo swelling that can both be detrimental and acceptable in different applications. In the Northern part of India, especially Delhi region, natural soils containing clays & clayey sands support most of the buildings. Mechanically stabilized clays mixed with sand are used for local earthwork construction such as roads and landfills. Exact understanding of the swelling behaviour of such soils is a prerequisite before the start of any construction projects. In this paper the swelling behaviour of clayey soil reinforced with geocell & Jute fibres has been presented. The laboratory investigations include one dimensional swelling tests using California Bearing Ratio (CBR) mould to study the swelling properties for different mix proportions. The maximum decrease in swelling potential of Geocell reinforced specimens was observed at fibre content of 0.80 percent and 40mm fibre length, beyond which increase in the swelling potential and swelling pressure has been observed. With this optimal reinforcement, a reduction of 71.24 percent in swelling and 41.10 percent in swelling pressure has been observed as compared to unreinforced soils. The study provides a solution towards the treatment of expansive soils before starting any construction activity over such soils and a step towards mitigating disasters related to infrastructure facilities grounded on expansive soils.

Geosynthetic-Reinforced Pile-Supported Embankments (GRPS) are widely used in infrastructure projects to improve load distribution and stability over soft ground conditions. They enhance the performance and durability of embankments in road, railway, and bridge construction by integrating geosynthetics and pile foundations. This study investigates the impact of various pile head shapes on the performance of Geosynthetic-Reinforced Pile-Supported Embankments (GRPS), an area not extensively studied previously. Five pile head shapes were analyzed: flat head, partial cone, and semi-spherical shapes of varying sizes. A 3D numerical modeling approach using PLAXIS 3D software was employed, beginning with validation of a case study, followed by examination of the effects of the five pile head shapes on stress reduction ratio, induced vertical stress, and ground surface settlement. Results showed that for circular piles with a flat head, increasing the pile head diameter from 1 meter to 1.5 meters reduced the stress reduction ratio from 0.38 to 0.26, highlighting the role of head size in enhancing soil arching. Additionally, changing the pile head shape from semi-spherical and partial cone to flat decreased the stress reduction ratio from 0.62 and 0.58 to 0.38, underscoring the effectiveness of flat head piles in augmenting soil arching within GRPS systems. Enhanced soil arching also corresponded with reduced ground surface settlement. Therefore, for GRPS projects, piles with larger, flat heads are recommended.

Stone columns are an effective approach to improving the bearing capacity of weak soils, which has led to increased interest in the improved soil method being further developed and expanded. In addition, enhancing the bearing capacity of stone columns has recently received great attention. This paper studies the effects of embedded concrete parts on the stone columns' bearing capacity and bulging failure. Moreover, arranging solutions to the problem of bulging failure and reduced bearing capacity of stone columns and understanding the stone columns' failure after reinforcement by comparing the results. Stone columns are either embedded in a solid concrete part or unreinforced were examined using large-scale laboratory experiments, and numerical simulation was performed using ABAQUS. The models test with a scale factor of 1:7 was employed. The results demonstrated that using a concrete part on the top of the stone column greatly increases its bearing capacity and the efficiency of the surrounding soil. Concrete-stone columns (CSCs) show stress concentration ratio (n) enhancement and significant resistance to bulging failure deformation. The concrete-stone column shows an enhancement related to increasing the concrete part length; also, the CSCs stiffness increases the surrounding loess soil capacity. The horizontal stresses of CSCs demonstrate the type of column failure behavior; the column may fail due to shear stress in a long concrete part case.

Various ground improvement methods have evolved in the last decade, these methods seek to improve the shear strength parameters of the soil and thus increase the bearing capacity. This paper, presents the reliability of the results of improvement techniques on Peaty clay soil, in various locations at a 1m depth, using the Unconfined Compressive strength test (UCS) and the California Bearing Ratio test (CBR). The major materials used where-Chemicals such as Calcium Oxide, Calcium Hydroxide, Calcium Chloride, Cement, Aluminum Hydroxide and Sodium Silicate and Geo textiles -woven soaked, non-woven soaked, woven un soaked and non-woven un soaked for a curing period of 7 days, 14 days and 28 days. Amongst the different methods of soil improvement, the use of chemical additives for soil stabilization to increase soil strength parameters and loading capacity was found to be more reliable. In addition, the above mentioned chemicals increased the shear strength of the soil and controls shrinkage-swell properties of the soil, hence, a reliable technique in improving soil properties. The use of geo textile was also found to be a reliable improvement technique because it generates strength improvement.

The issue of interaction between nearby footings is of paramount practical significance. The interference effect should be taken into account since the footing may really be separated from or bounded by other footings on one or both sides. In this regard, this paper studies the effect of two nearby interfering strip footings embedded in saturated cohesive soils, which will help to provide a better understanding of the impact of footing depth on the interference effect. A numerical study is carried out using the finite element program (Midas GTS-NX), and the behavior of closely placed strip footings embedded in the saturated cohesive soils is investigated under the influence of different factors such as the spacing between footings, the depth of footings, soil undrained shear strength, and the groundwater table. It was concluded that the soil cohesion and the footing depth ratio have a notable influence on the interference of closely spaced footings. For all cohesion values, it has been observed that the spacing needed for interference to vanish decreases with an increase in the depth of the footing and water table. In addition, as the S/B ratio increases, the ultimate bearing capacity (UBC) of interfering footings decreases until it reaches the same value as an isolated footing at greater spacing. The UBC is approximately 10% higher at S/B = 1 compared to the isolated footing. However, at S/B = 1, the UBC of two footings achieves a value equal to that of an isolated footing and does not change when the S/B ratio increases. With increasing footing depth, there is an increase in UBC. Finally, the highest values of were obtained in all cases when Cu = 40 kPa. This indicates that the interaction between footings is greater when the soil is softer.

Indonesia is a tropical country threatened by many disasters, such as earthquakes and other collateral hazards (liquefaction). Utilization of micro pile on the liquefaction prone areas is quite popular to increase the soil bearing capacity. In this research, Eucalyptus Pellita Timber was used as micro-piles alternatives. This study aims to determine the effect of timber pile addition on soil settlement and the increase in bearing capacity. Some laboratory investigations were conducted, such as timber and soil physical and mechanical characteristics, preloading tests, and seismic load tests by using small-scale shaking table test. The preloading tests were carried out for 40 days, and the settlements were recorded every 24 hours. Subsequently, seismic load tests were conducted on sandy soil with Dr = 40%. The seismic duration was 37 seconds, with PGA = 0.3 g and f = 0.78 Hz. The preloading test results show that Eucalyptus pellita timber piles are able to reduce the settlement by 18%. and from seismic load testing results are able to reduce the settlement by 68% due to earthquake loads with PGA = 0.3g and a frequency of 0.78 Hz on sandy soil with the potential for liquefaction. This is due to the resistance at the tip of the pile and the skin friction on the timber pile. So, from the results of the model test, it shows that the use of Eucalyptus Pelita timber piles can be used as an alternative to handling sandy soils in areas where liquefaction has the potential to occur.

One method to deal with the problem of soft soil is to accelerate consolidation by preloading and prefabricating a vertical drain (PVD). Consolidation analysis was based on a one-dimensional theory that required PVD as an equivalent circular well. Further studies on a simple approximate for consolidated soil were represented by equivalent permeability coefficients, kve. The equivalent conductivity coefficient is influenced by the soil and PVD permeability coefficients. The formulation of kve based on the influence area in cylindrical has been applied to a lot of construction projects. According to the comparative analysis of the classical consolidation theory, it is considered that the diameter of the circle is less representative. This study proposed a simple formulation of kve based on the elliptical assumption of influence area. The kve was derived based on an equal average degree of consolidation in one dimension, which applied the elliptical coordinate for degree of consolidation in the radial direction. The formulation is based on an elliptical cross-section and a cylindrical coordinate formulation. The validation of this formula is conducted with numerical calculations using 2D FEM. The results show that the consolidation time in the elliptical discharge area is shorter than that in the circular discharge area.

Expansive soil is a form of soil that can expand and contract, changing its volume. Montmorillonite, a mineral with the ability to dissolve in water, makes up the majority of these kinds of soils, and by increasing the volume of the soil, it causes the soil to heave. Expansive soils could be a substantial concern for engineered buildings due to their capacity to adjust to seasonal variations by contracting or expanding moisture content. Many researchers focused on soils that were swollen and looked at how they behaved as well as how they could be improved. In this study, the work depends on inserting micropiles with different depths and configuration widths to investigate which depth and configuration can be obtained to improve the bearing capacity of foundations on expansive soil. The main purpose of this study is to reinforce the expansive soil with micro-piles with different depths (1B, 2B, and 3B) and different configuration widths (under footing only, 1B and 2B). It was concluded that the soil reinforced with micro-piles improved the load-bearing capacity of the expensive soil and decreased the swell pressure. The increasing depth of the micropiles 2B to 3B (B is the width/diameter of the foundation) can increase the bearing capacity by just 6%; therefore, increasing the depth beyond 2B is not beneficial. Also, the increase in width of the configuration of the micro piles from 1B to 2B increases the bearing capacity by just 4%; therefore, the increase in width greater than 1B is not valid.

Soft peat soils are located in many zones and at a given depth all over the world and are characterized by their low shear strength and high settlement. It can also cause progressive failure of roads, embankments, and foundations. Sand cushioning is the most beneficial technique used to relieve the stress transmitted to the peat layer to mitigate any deformation and shear failure. In this research, a field study of a road with a soft peat layer located at a depth 4m below the ground surface is carried out. The plate load test is conducted on three cases over the peat layer using sand cushions with and without reinforcement. The results were compared with plate footing on the surface of the road without stabilization. The field tests of the improved technique were verified and deeply analyzed using the numerical program Plaxis. The finite element analysis mainly sheds light on the simulation of the dynamic response that represents the compaction of the sand cushion over the peat layer. A series of numerical models has been done considering the effect of repeated load compaction on the adopted sand cushions with and without reinforcement. The numerical analysis is directed to show the effect of repeated loads of compaction equipment that were used on decreasing the stress over the peat layer. The results showed that the composite compacted cushion with both a higher number of cycles and stress has a great effect on relieving the stresses transmitted to the face of the peat. As a result, the footing capacity is increased with less deformation.

Considering a unit cell model, this paper illustrates the increase in stiffness modulus of a soft clay after vibro-compacted stone column installation. Using the Plaxis software calculations were conducted using for the soft clay perfectly plastic and hardening-soil models. The column installation was simulated as lateral expansion in the soft clay. The influence of improvement area ratio, thickness of sand layer surcharge and radius of the soil body in which the expansion occurs were studied through analysis of stress states in the clay surrounding the column. Comparison of stress states before and after a partial consolidation in the soft clay leads to a soft soil modulus improvement prediction equal to 40% when using the perfectly plastic model while the prediction with the hardening-soil model leads to an improvement of 75%. Taking into account the improvement of soft clay stiffness could lead to substantial savings in the quantity of stones needed, when compared to the present design uses.

The settlement of foundations is usually predicted by the oedometric method and/or by the pressuremeter method. However, the settlement of a foundation can be predicted from Boussinesq formula via the Young modulus, especially in the absence of oedometric or pressuremeter data. This paper aims at, firstly, a highlight on the conditions for the applicability of oedometric and pressuremeter methods, and, secondly, a possible comparison between estimated settlements by the two methods. Such a comparison is still a matter of debate between the soil engineers, especially those who are faced to the design of foundations projects. Here in, it is out of interest the validity of results obtained from the oedometric or pressumeter test, it is assumed that the available data are reliable, well-defined according to standards, both for carrying out the experiments and for the treatment method in order to retain the oedometric or pressuremeter characteristics. Concluding remarks are justified based on the analysis and discussion of two case histories.

Deep drainage technique utilised for flood mitigation in low-land coastal areas of Australia during the late 1960s has resulted in the generation of sulphuric acid in soil by the oxidation of pyritic materials. Further degradation of the sub-surface environment with widespread contamination of the underlying soil and groundwater presents a major and challenging environmental issue in acid sulphate soil (ASS) terrains. Although several ASS remediation techniques recently implemented in the floodplain of Southeast Australia including operation of gates, tidal buffering and lime injections could significantly control the pyrite oxidation, they could not improve the long-term water quality. More recently, permeable reactive barriers (PRBs) filled with waste concrete aggregates have received considerable attention as an innovative, cost-effective technology for passive in-situ clean up of groundwater contamination. However, long-term efficiency of these PRBs for treating acidic groundwater has not been established. This study analyses and evaluates the performance of a field PRB for treating the acidic water over two and half years. The pilot-scale alkaline PRB consisting of recycled concrete was installed in October 2006 at a farm of southeast New South Wales for treating ASS impacted groundwater. Monitoring data of groundwater quality over a 30 month period were assessed to evaluate the long-term performance of the PRB. Higher pH value (~pH 7) of the groundwater immediately downstream of the PRB and higher rates of iron (Fe) and aluminium (Al) removal efficiency (> 95%) over this study period indicates that recycled concrete could successfully treat acidic groundwater. However, the overall pH neutralising capacity of the materials within the barrier declined with time from an initial pH 10.2 to pH 7.3. The decline in the performance with time was possibly due to the armouring of the reactive material surface by the mineral precipitates in the form of iron and aluminium hydroxides and oxyhydroxides as indicated by geochemical modelling.

Acidic groundwater generated from acid sulfate soil (ASS) usually carries high concentrations of aluminium (Al) and iron (Fe), which create unfavourable conditions to living habitat. ASS research team at the University of Wollongong, Australia implemented an innovative geotechnical engineering technique for the remediation of acidic groundwater through a permeable reactive barrier (PRB) using recycled concrete aggregates as the reactive material. This PRB was installed at the Shoalhaven Floodplain, southeast New South Wales (NSW), Australia in October 2006 and has proved effective in neutralisation of groundwater by increasing the pH from 3.6 to 7 and removing 99% of Al and Fe from groundwater to date. Dissolved Al and Fe were removed through continuous precipitation which would clog the pore spaces of reactive medium by secondary mineral precipitation. This paper provides a complete evaluation of the performance of the PRB through field work and groundwater flow modelling coupled with geochemistry. The developed model (using finite difference codes: MODFLOW and RT3D) describes the chemical clogging due to mineral precipitates and the associated reductions in porosity and hydraulic conductivity of the reactive medium. The results obtained from numerical modelling, groundwater samples analysis and mineralogical analysis of barrier specimens confirm that the current PRB has performed well since the last seven years. Only a smaller amount of clogging was evident at the entrance of PRB with only a 3% reduction of hydraulic conductivity. This model would be beneficial for the environmental scientists and geotechnical engineers who have to deal with the ASS problems, especially in coastal Australia.

Acidic groundwater, generated from acid sulphate soil (ASS) is a major geo-environmental problem in Australia. Manipulation of groundwater through the use of weirs and gates in the nearby creeks and drains of ASS, which is being practised right now for preventing pyrite oxidation, are not effective in low land floodplains due to the risk of flooding. The application of permeable reactive barrier (PRB) can be a novel alternative for remediation of acidic groundwater in such floodplains. Laboratory column experiments were carried out prior to installation of the PRB for examining the efficiency of the material. Results of these experiments have shown that recycled concrete could effectively neutralise the acidic water for longer period with complete removal of aluminium (Al) and iron (Fe). Despite the reduction of the efficiency of the recycled concrete due to armouring by accumulated precipitates of Al and Fe, excellent performance of the recycled concrete was observed for an extended period under controlled laboratory condition. Following these results, a pilot PRB was installed in the Broughton Creek flood plains in southeast NSW to observe its performance under varying natural conditions of the field. The PRB has been maintaining near neutral pH with complete removal of Al and Fe from the groundwater of ASS matching with the results of column test. The promising performance of the pilot PRB for last three years shows that PRB can be used as one of the cost effective and environmental friendly alternative to the recently utilised other techniques in ASS.

Paper deals with the problem of foundation on the soft soil in seismic active regions. In these regions special measures for foundation and sub-base preparation must be taken. Our company deals a lot with soil improvement in loose and soft soils with high ground water levels. The special technique for soil improvement using geosynthetics is developed. The foundation on this soil is problematic and the soil characteristic must be taken into consideration in the early phase of the structural design. The whole structure, taking into consideration the structure stiffness, must be modeled and examined in static and dynamic loads. Structure is modeled by Plaxis software, with subsoil and improved tampon layer and geosynthetics layer(s) between the subsoil and tampon layer. The earthquake response for real earthquake input is analyzed. The stresses, strains and deformations are analyzed in soil and synthetics layers. Experiences not only from analysis but from constructions of the improvement from several sites are discussed and illustrated in the paper. As a result of our analysis and long years of theoretical and practical experience the recommendations for shallow foundations soil improvement are given.

Amalan keselamatan makanan merupakan aspek penting dalam mengelakkan dan mengawal risiko penyakit bawaan makanan di premis makanan terutama di dewan makan asrama sekolah. Pengendali makanan merupakan individu yang bertanggungjawab dalam memastikan makanan yang disediakan selamat dan bersih. Kajian ini bertujuan untuk mengenalpasti tahap pengetahuan, sikap, kreativiti dan inovasi terhadap amalan pengendali makanan. Hubungan amalan keselamatan makanan antara pengendali berdasarkan jawatan, pengalaman bekerja, menghadiri kursus pengendalian makanan turut dikaji. Persampelan bertujuan digunakan kepada 55 orang pengendali makanan yang bekerja di dewan makan lapan buah Kolej Vokasional Negeri Johor. Instrumen yang digunakan adalah soal selidik dan senarai semak pemerhatian serta temubual berstruktur sebagai data sokongan. Data yang telah diperolehi dianalisis menggunakan perisian Statistical Packages for Social Science (SPSS) 20.0 untuk mendapatkan nilai kekerapan, skor min dan sisihan pi...

The main objective of this study is to examine the applicability of various CPT-SPT correlations available in the geotechnical literature to relatively young calcareous sand in the Persian Gulf area. These correlations were compared with high quality CPT and SPT data collected from various projects in the UAE area. The study results indicated that almost all of the existing correlations are not applicable to the fine to medium grained sand in the UAE and that the ratio between normalized cone tip resistance and SPT blow counts is relatively higher than the typical values in the geotechnical literature. The study results were used to develop region-specific CPT-SPT correlations for the calcareous sand in the UAE. Statistical analyses were also performed to quantify the uncertainty in these correlations and to develop risk-based CPT-SPT correlations

This paper presents a comprehensive study on the improvement of soft soils using the stone column technique. Through a combination of experimental testing and literature analysis, the behavior of black cotton and red soils under various loading and moisture conditions is analyzed. The research demonstrates a significant increase in the bearing capacity of soils treated with stone columns. Notably, black cotton soil exhibited an enhancement of up to 7.8 times under dry conditions and 2.7 times under soaked conditions. The study further evaluates the impact of h/d ratios and explores the comparative performance between black cotton and red soils. The findings support the application of stone columns as an effective and economical ground improvement method in geotechnical engineering.

Conventional ways of reinforcing soil embankments such as packing earth layers densely may not provide much strength to withstand immense weights. In this case, using geogrids, a type of geosynthetic material, among the soil layers can show satisfactory result in strengthening soil embankment. The primary aim of this research is to assess the effectiveness of geogrid reinforcement in mitigating embankment's settlement and improvement of overall stability through a comprehensive numerical study. To achieve this objective, a detailed numerical modelling approach with five phases of 0.5m height embankment, at a 1:20 scale is employed using FEA (Finite Element Analysis) by Plaxis3D(CE V20 input) software, representing the embankment both without and with geogrid reinforcement, surface-to-surface (soil-geogrid layer) interaction, boundary conditions and application of statically uniform rail load. Here, Mohr Coulomb model for soil and elastoplastic model is used for geogrid. Effects of both multilayer and single layer geogrids at different depth are analyzed. The obtained result which has shown the optimal performance enunciates that 99.46% of settlement is reduced and 12.13% of failure stress is increased, when geogrid is used at 0.048m depth in a 10m high soil embankment. Overall, this research underscores the importance of considering geogrid reinforcement as a sustainable and cost-effective strategy.

The predictions of bearing capacity and settlement by using the group of columns model essentially constitute the first required steps for the design of columnreinforced foundations. The bearing capacity of reinforced soft clay by sand and stone columns is evaluated trough the validation of laboratory and in situ experimental records. Based on all results, an overall methodology of design is comprehensively formulated for foundation on reinforced soils by columns. The suggested methodology, that is applicable to all practical projects, essentially aims to optimize the quantity of columns' material which controls the cost of reinforcement. Major conclusions derived from results of research work have been programmed in software, entitled "Columns". Several case studies have proved the usefulness of the software that offers a novel tool of design for foundations on reinforced soil by columns. The usefulness of developed software is shown through analysis of a study case of embankment on soft clay.

Properties and characteristics of soft clays are presented. Because several problems are faced, when projects construction is intended on soft clays, several improvement techniques can be adopted. Preloading with or without vertical drains, vacuum consolidation and reinforcement by columns are currently used to enhance properties of soft clays. Also, rigid inclusions and geotextiles may be used. The principles and basic criteria for the design of all these techniques are explained. Comparison between advantages of improvement techniques is carried out by illustration of typical case histories.

This paper focuses, first, on problems related to the identification and classification of soft clays. The determination of physical parameters and mechanical characteristics of Tunis soft clay is presented. The
difficulties, that may lead to overestimated values of soil characteristics, is debated especially when tests are carried out on remolded soft clays. A method has been proposed to avoid overestimated undrained
cohesion from vane shear test. Then, the study of the behavior of soft clays is evoked. To model the
behavior of Tunis soft clay the modified Cam Clay (MCC) model is justified. Parameters of MCC model,
from experiments, are incorporated in Plaxis software (version 8.0) that served for assessment of the
observed behavior of Tunis soft clay. The possibility of improved performance of soft clays by stone
columns is presented. Because of lateral expansion during columns installation, and subsequent
consolidation prior to final loading, the parameters of soft clay are significantly improved. A methodology
based on numerical implementation by the use of Plaxis software permitted to evaluate the rate of increase of the modulus of elasticity of soft clay and the radius of the area surrounding the column where it occurs.
Keywords: soft clay , behaviour, model, improvement, experiments, remoulding, numerical, prediction.

Tunis soft clay belongs to the category of problematic soils because of its weak strength characteristics, high compressibility and high content of organic matter (22%). Deep mixing column (DM) presents a well-developed technique to improve the properties of Tunis soft soils by increasing its bearing capacity and reducing settlements. This paper describes a laboratory experimental program performed to assess the effectiveness in improving the shear strength of Tunis soft clay. The two mains objectives of this research are to evaluate the effect of reinforcement by DM on the behaviour of the Tunis soft clay and to investigate parameters of influence on its strength characteristics. Five parameters are studied from the performed tests: (1) curing time: CT = 7, 14, 21 and 28 days; (2) injection pressure: IP = 50, 100 and 150 kPa; (3) water-cement ratio w/C = 0.7, 1 and 1.2; (4) rotation rate V = 15, 30 and 40 rpm and (5) consolidation pressure: , 3 = 100, 150 and 200 kPa.

The numerical behavior of rafted foundation resting on soil reinforced by rigid inclusions is undertaken. Axisymmetric modeling of scaled test model investigated primarily in the framework of ASIRI research project is investigated by the FE code Plaxis V9.2D. The predictions of settlement and efficiency of the reinforced soil are compared to measurements obtained from tests carried out in the calibration chamber. A parametric study was conducted and allowed to observe the effect of the thickness and the constitutive material of mattress layer, the cover rate and type of compressible soil on the efficiency of the reinforcement by rigid inclusion. Main findings were: the best efficiency is obtained for minimum thickness of mattress layer. The increase in cover rate leads to an increased maximum efficiency and settlement reduction.

An experimental investigation was carried out on the reconstituted Tunis soft soil (TSS) that was extracted from the centre of Tunis City at 35-m depth. Three series of consolidation tests were performed on TSS specimens. The first series included consolidation tests by preload. In the second series, vacuum consolidation tests were performed. The third series comprised a vacuum consolidation test combined with the preload. Excess pore water pressure and settlement were measured during the consolidation tests. Experimental results showed that for the same magnitude of preload and the vacuum pressure of 4, 8, 16 and 30 kPa, the settlement caused by the vacuum pressure is lower than that generated by the preload, while the settlements generated by preloads of 60 and 100 kPa are slightly lower than those caused by vacuum pressure of 60 and 100 kPa. A rapid dissipation of recorded excess pore water pressure around the geodrain was observed compared to that measured close to the cell border.

This paper presents an experimental study carried out on undisturbed cored samples of Tunis soft soil extracted at 17.25 m depth at the lagoon of Sejoumi. Three series of oedometer tests were performed: the first one was a standard test on Tunis soft soil, the second one was performed on the same soil improved by a prefabricated vertical drain Mebradrain 88 (Mb88) type during which vertical drainage was prevented. The third series comprised similar tests to those of series two, during which horizontal and vertical drainage were allowed. The assessment of Carillo's theory was studied by quantifying the effect of radial and vertical consolidation from the observed global degree of consolidation of improved Tunis soft soil specimens by geodrains. The rate in decrease of coefficients c r and k r was greater than that recorded for coefficients c v and k r , respectively. Using the Carillo's theory, a lower degree of consolidation which starts from 10 % is obtained; however, when using simple approximate methods by considering recorded measures from series 3, higher degrees of consolidation starting from 70 % were obtained.

This paper studies the prediction of behaviour of foundations resting on a soil reinforced by sand and stone columns. The preliminary design is based on an optimized improvement area ratio predicted by the methodology proposed by Bouassida & Carter (2014). The prediction of the behaviour of the reinforced soil is predicted by numerical computations carried out by Plaxis V9.2D and FLAC3D codes in plane strain and axisymmetric conditions. A Tunisian case history of oil tank is investigated. When assuming the linear elastic behaviour for constituents of reinforced soil, it is noted that the predictions of settlements given by Columns 1.01 software are in good agreement with numerical results obtained by Plaxis and FLAC3D codes. Comparison between those approaches shows the validity of results using the Columns 1.01 software. By adopting the Mohr-Coulomb failure criterion for columns material and the hardening soil model for soft clay, the evolution of long term settlement predicted by Plaxis code showed the acceleration of the consolidation of the compressible soft clay due to the enhanced drainage property of column material.

Portland cement can be mixed with sand to improve its mechanical characteristics. Considering the inherent anisotropy of most sands, it is not clear whether the added cement shall contribute to equal increases in strength and sti ness in vertical and horizontal directions or not. Literature review reveals that all the previous experimental studies on the cement-treated soil topics are limited to conventional triaxial device test results. The e ect of cement addition to clean sand in more sophisticated stress-path controlled devices like \Simple Shear Apparatus" (SSA) and \Hollow Cylinder Apparatus" (HCA) for simulating more realistic loading conditions, such as earthquake, have not been investigated yet. This paper presents innovative methods for testing arti cially cemented sands through making modi cations to the loading platens, specimen molds, and specimen preparation methods of SSA and HCA. Undrained tests under di erent monotonic stress paths were carried out on di erent mixtures of Portland cement with clean sand to investigate the e ect of principal stress rotations. The test results revealed that the cement mixture reduces the anisotropy, while it improves the mixture mechanical properties compared to the compacted uncemented sand.

The shear strength at sand-geogrid interfaces under direct shear conditions is traditionally estimated using the empirical equation proposed by Jewell et al. (1986). This study enhances the original formulation by introducing an area reduction factor to account for the influence of soil density on the interaction mechanism. The modified approach enables a more comprehensive evaluation of shear resistance, including soil-soil, soil-geogrid, and overall system behavior, as well as passive bearing resistance. The revised framework is employed to assess various backfill materials, facilitating the selection of suitable options for geotechnical applications involving geogrid reinforcement.

Geogrid reinforcement is a widely used technique for improving the mechanical properties of infrastructure engineering structures. However, there is limited understanding of the behavior of geogrid with different aperture shapes when used as reinforcement in plain concrete footings. This paper presents a comprehensive study that investigates the effects of five different aperture shapes of geogrid reinforcement on the load-deformation behavior and crack propagation of plain concrete footings. The study also aims to provide a basis for future research on the use of geogrid as reinforcement in thin concrete overlays. The five geogrid products used in this study were characterized based on their index material properties, and were used in combination with fiber glass reinforced concrete (FGRC) and normal concrete mixes. The experiments were conducted on both unreinforced footings and footings reinforced with one layer of geogrid. A distributed static load was applied to simulate the stress of reinforced footings. The experimental results indicate that the strength resistance of the geogrid reinforced footings is significantly improved compared to the unreinforced footings. The use of glass fibers and geogrid confinement in the footing designs were found to have a significant impact on improving the load-deformation behavior and crack propagation. Furthermore, the study reveals that the strength and dimensions of the geogrid reinforcement play a crucial role in determining the behavior of the plain concrete footings. Also, the Comparison between cast and load capacity of all samples was presented.

The aim of the study was to determine the shear strength of mineral and anthropogenic soil of similar grain size as a function of the applied shear rate and water saturation. Stability calculations using the finite element method of the road embankment model were also carried out to demonstrate the variation in factor of safety values depending on the adopted values of the angle of internal friction and cohesion. The tests were carried out in a direct shear apparatus in a 100 × 100 mm box with a sample height of 20.5 mm. The samples were formed directly in the apparatus box at optimum moisture content until a compaction index of I S = 1.00 was obtained. Tests were carried out under conditions without and with water saturation at shear rates of 0.01, 0.05, 0.1, 0.5 and 1.0 mm•min -1 until 18% horizontal displacement was achieved. The results showed that the effect of shear rate on the strength parameters was not unequivocal and was much smaller than the changes caused by saturation of samples. An increase in shear rate resulted in small changes in the angle of internal friction with a tendency towards a decrease. In contrast, cohesion varied over a much larger range with increasing shear rate, with an apparent initial decrease and subsequent increase. The saturation of the samples resulted in a decrease in the angle of internal friction of the cohesive soil and an increase for the ash-slag mixture. The cohesion of both soils decreased. The results obtained from the road embankment model stability calculations confirmed that soil saturation had a greater influence on the factor of safety values obtained than the shear rate.

Infrastructural development effort on soft clay deposits that exhibit excessively low bearing capacity and potential for large settlements poses a challenge for geotechnical engineers. An adequate ground improvement program to achieve proper consolidation is thus a prerequisite for both long-and short-term stability. Pre-construction consolidation using surcharge load alone not only takes too long but also practically quite cumbersome and costly to achieve 90% consolidation. A surcharge preloading along with an arrangement of vertical drains when combined with vacuum pressure makes an attractive ground improvement alternative. This reduces the cost of stabilization and increases the effectiveness of the combined system. The provision of negative pressure in the vertical drains intensifies radial flow of porewater that expedites consolidation. This paper discusses nuances of this system and identifies factors to improve its effectiveness.

The social, economic, cultural and industrial growth of any country depends heavily on its transportation system. The only mode which could give maximum service to one and all is transportation by highways and railways. As a result of development of infrastructures like buildings, highways, railways, and other structures in recent past years has resulted in scarcity of good quality of land for construction projects. Aim of this project is, study the various construction method adopting for improve the soil or ground. Every method had it’s own pros and cons, which will help to decide the most suitable method for problematic soil to improve it’s capacity. So it can be available to carry each type of civil engineering structures. Selection of method based on situation and required results, here are taken case study of Coastal road project. Project duration and economy also main factor affecting on selection.
Keyword: Stone Column, Soil, Ground Improvement, cost effective

Deep Soil Mixing (DSM) is a ground modification technique to improve soil characteristic. This paper explain the result of laboratory experiment of deep soil mixing (DSM) in small scale. The model have been constructed to estimate field condition. The important properties of expansive soil such as the strength and swelling were investigated. The fly ash was used as binder material to enhance strength and mitigate swell potential. However optimum binder dosage, water -binder ratio and geometrical column (length, diameter and spacing) influenced performance of DSM. Variation of length and spacing of column could be established by considering active zone and the area ratio in the single square arrangement. The required treatment area are determined based on tolerable swelling and allowable bearing capacity. The small scale of DSM construction showed significant improvement of swell and strength properties compare with untreated soil. The empirical model are presented in this research provided reasonable predictions of strength and swelling for in situ condition.

Coupled finite element analyses of the consolidation and deformation around stone columns have been performed to assess the accuracy of different analytical solutions. The numerical model reproduces the hypotheses of the closed-form solutions. In the model, a rigid load is applied to a unit cell formed by a fully penetrating column and its surrounding soil, and simple elastic or elasto-plastic soil models are used. The surface settlement, the dissipation of the pore pressure and the vertical stress concentration on the column are studied. These soil responses are accurately estimated with closed-form solutions that properly include the radial and plastic strains in the column. However, the surrounding soil does not yield for usual conditions, which reasonably justifies the elastic soil behavior assumed in the analytical solutions. The differences between drained and consolidation analyses are also evaluated. Comparing the numerical results with the closed-form solutions illustrates the implications of the assumptions of each approach.

This paper discusses the design and construction of the foundation for a bridge approach embankment which consists of back-to back mechanically stabilized earth walls (MSE) constructed within a wetland area. The walls are highest at the bridge abutment with a maximum height of 10 meters. Soil improvement was undertaken to provide suitable foundation for the approach embankment. The soil improvement consisted of installation of vibro concrete columns (VCC) penetrating the soft soil into suitable sandy soil layers in conjunction with a geotextile reinforced sand platform to transfer the embankment fill load to the VCC. This solution constituted the first use of VCC by a US Department of Transportation to support an approach embankment. The design concept of the embankment supporting system is outlined. However, emphasis is given to the behavior of the geotextile component of the system. The performance of the embankment supporting system is assessed based on monitoring data obtained f...