Cyclic Triaxial Test

This paper presents an experimental study on the influence of the principal stress direction and magnitude on the stress-strain-strength behavior of Bangkok Clay. The results of undrained torsion shear hollow cylinder test with various principal stress directions and various magnitudes of intermediate principal stress on undisturbed Bangkok Clay specimens are presented and analyzed. The discussions include: (i) stress-strain and pore pressure behavior, (ii) stiffness characteristics, and (iii) strength characteristics. The results show some evidences of anisotropic behavior of Bangkok Clay in various aspects.

Peats originate from plants and denote the various stages in the humification process. This condition renders the peat extremely soft and can be considered problematic soil. Thus, this study is conducted to examine and comprehend the particularities of peat engineering behaviour in respect to the relationship effects to the shear stress and cyclic shear strain of peat soil various characteristics to establish suitable correlation. This study carried out by using triaxial testing described by geotechnical test standards BS-1377: Part 8: 1990. Methods of Testing Soils for Civil Engineering Purposes: Shear Strength Tests (Effective Stress) that required for consolidated undrained and consist of five main stages: saturation, consolidation, static, dynamic, and post-cyclic loading using the GDS Enterprise Level Dynamic Triaxial Testing System (ELDYN). The parameters of shear strength were obtained in the peak deviator stress at a maximum of 20% of axial strain by using an undisturbed sample with an effective pressure imposed of 25, 50, and 100 kPa. In this study, all specimens are subjected to cyclic loading up to 100 cycles based on a one-way loading system with strain-controlled conditions. Based on the analysis conveyed, the post-cyclic shear stress decreased compared to its initial value of about 65.56 kPa (PNpt-100 kPa) in static and decreased to 14.9616 kPa in post-cyclic (PNpt-25 kPa-1 Hz). The principal stress ratio (σ'1/σ'3) shows the maximum values of this ratio that are located in the narrow zone of 1.61 to 1.12.

The most important parameters in evaluation of dynamic behavior of soil structures such as highways, retaining walls, and embankments are shear modulus and damping ratio. A fiber reinforced soil behaves as a composite material in which fibers of relatively high tensile strength are embedded in a matrix of soil. Shear stresses in the soil mobilize tensile resistance in the fibers, which in turn imparts greater strength to the soil. This study deals with assessment of fine sand reinforced with carpet and geotextile strips when subjected to dynamic loading by performing two sets of cyclic triaxial test-large scale and small scale. In these tests the influences of various parameters such as confining pressure, mixture ratio, and the ratio of strip length to its thickness which will herein be referred to as aspect ratio on the dynamic behavior of reinforced fine sand were studied. The results demonstrate that the effects of this kind of reinforcement on shear modulus in low confining pressures (less than 100kPa) are negligible and in high confining pressures are considerable.

Suction caissons are more and more used for offshore foundations. This paper deals with the cyclic modelling of suction caissons using the Prevost's model. The case study is a 8m large diameter caisson embedded in dense No. 0 Lundsand. Parameters for the model are calibrated using drained triaxial tests. A parametric study concerning the influence of the constitutive law, the skirt length and permeability is carried out.

The design of deep dump slopes for opencast mines usually requires information about the soil resistance to liquefaction during earthquakes. This resistance depends not only on the initial stress, the initial density, and the amplitude of the cyclic loading, but also on the preshearing, that is, the deviatoric stress path applied to the soil before the cyclic loading. To explore the influence of preshearing on the subsequent soil behaviour, a set of triaxial tests with a combination of undrained preshearing and drained stress cycles using two sample preparation methods is presented. It is shown that the preshearing as well as the preparation method have a major influence on the strain accumulation upon cyclic loading. Simulations of the experiments with four advanced constitutive models reveal that neither the long-lasting effect of preshearing nor the preparation method can adequately be captured by all of the models. This deficiency of the constitutive models can lead to unsafe de...

Over the last years rubber from scrap tyres has been reused in different civil works such as road embankments and railway platforms due to its resilient properties, low degradation and vibration attenuation. Unfortunately, this issue is still scarce. For instance, in Spain about 175.000 tonnes of scrap tyres were collected in 2014, of which only 0.6% were reused in civil works. Aiming to contribute to the reutilisation of large quantities of this waste material, this paper focuses on the analysis of unbound mixtures of granular materials with different percentages of rubber particles to be used as subballast layers. Mixtures are tested under cyclic triaxial tests so as to obtain their resilient modulus and evaluate their permanent deformations. It is found that as the rubber content increases, the resilient modulus decreases and the permanent deformation increases. Taking into account the usual loads transmitted to the subballast layer, the optimum rubber content that does not compromise the behaviour of the mixture is set in a range between 2.5% and 5% in terms of weight.

This research study was performed to examine the appropriate treatment/stabilization schemes for very weak subgrade soils at high water contents, and to evaluate the corresponding performance-related properties [e.g., resilient modulus and permanent deformation] for use in the design and analysis of pavement structures. Five different soil types, that represent the typical range in subgrade soils in Louisiana, were collected and considered in this study. Three different moisture contents (at the wet side of optimum), producing a raw soil strength of 172 kPa (25 psi) or less, were selected for treatment/stabilization. The percentage of cementitious stabilizer (lime or cement) was determined to achieve a target 7-day strength value of 345 kPa (50 psi), as treatment for working table applications, and 1034 kPa (150 psi), as stabilization for subbase applications. Repeated load triaxial (RLT) tests were performed on the laboratory-molded treated/stabilized specimens in order to evaluate their resilient modulus and to study their deformation behavior under cyclic loading. A good correlation was observed between the water/cement ratio and both the resilient modulus and the permanent deformation of the specimens. The soil specimens were compacted at low water/cement ratios and showed better performances than those compacted at high water/cement ratios. The test results also showed that the use of a direct correlation between the unconfined compressive strength (UCS) and the resilient modulus for cementitiously stabilized soil can be misleading. In the case of heavily treated/stabilized subgrade soils for subbase applications, the permanent deformation of this layer can be ignored in pavement design.

This pa per p resents an e xperimental investigation f or i nherent ani sotropy an d particle breakage f or n atural Ras en-Naqab sand so uthern J ordan. The nat ural s and s pecimens were subjected to one dim ensional compression to induce breakage. Th e grain size distributions of the s pecimens were re ported before and aft er th e application of the stre sses. The reafter, t he sand s hear st rength parameters were asses sed using direct shear box t ests. E xamining t he obtained results revealed that the amount of breakage due to one dimensional compression is of order higher t han t he amount occ urring d uring di rect shear t est. Peak shear s trength parameters h ave little o r no ch ange w ith in creasing particles b reakage. H owever, d ilatancy component o f shear st rength di minishes w ith i ncreasing the am ount of part icles breakage. Moreover, exa mining t he effect of a ngle of de position shown a cons iderable am ount of dilation occurs on the higher deposition angle regardless the extent of breakage reported.

The effective stress concept has been introduced by many geotechnical experts, prominently by Terzaghi (1936), Bishop (1959), Bishop and Henkel (1962) (as summarized by Simons & Menzies, 2001). The effective stress is the real stress that occurs in the soil particles. That's the only stress that causes deformation to the soil skeleton. As it will be cleared in the next section, pore pressure is generated when the load is applied, but it doesn't cause any change in the deformation of the soil. Moreover, it's the effective stress that controls the shear strength of soil in drained conditions since water has no shear strength.
In this article, a modified version of Kelvin-Voigt viscoelastic model is applied to the problem of 1D soil consolidation to simulate how effective stress in soil skeleton is changed during the consolidation process.

In this paper the effects of maximum particle size, particle gradation/sorting and fabric on bulk mechanical behaviour of granular materials such as coarse grained soils and rock¢lls are investigated from micromechanical considerations starting from the grain scale level, using numerical simulations based on Discrete Element Modelling (DEM). Hydrostatic compaction and biaxial tests on 2-dimensional assemblies of discs with varying particle sizes and gradations were modelled using DEM. An examination of the constitutive behaviour of granular media considering the particulate nature of the medium has been attempted to explain the effect of particle size and gradation. Simulation results on perfectly parallel graded assemblies indicate that with increase in the size of the particles, a marginal increase (or no increase) in the angle of internal friction is observed during biaxial loading conditions. A change to a wider gradation (keeping the minimum grain size the same) results in a decrease in the angle of internal friction and an increase in volumetric strain to a considerable extent. Based on micromechanical force and fabric parameters, the basis for the physical behaviour was established. This helps in understanding the physics of parallel gradation techniques.

The most important parameters in evaluation of dynamic behavior of soil structures such as highways, retaining walls, and embankments are shear modulus and damping ratio. A fiber reinforced soil behaves as a composite material in which fibers of relatively high tensile strength are embedded in a matrix of soil. Shear stresses in the soil mobilize tensile resistance in the fibers, which in turn imparts greater strength to the soil. This study deals with assessment of fine sand reinforced with carpet and geotextile strips when subjected to dynamic loading by performing two sets of cyclic triaxial test-large scale and small scale. In these tests the influences of various parameters such as confining pressure, mixture ratio, and the ratio of strip length to its thickness which will herein be referred to as aspect ratio on the dynamic behavior of reinforced fine sand were studied. The results demonstrate that the effects of this kind of reinforcement on shear modulus in low confining pressures (less than 100kPa) are negligible and in high confining pressures are considerable.

Clay shale has unstable properties even though it is on a slope having a gentle slope. This raises many geotechnical problems. This study aims to determine the effect of clay shale drying on compressive strength and durability reduction by using samples taken from Kandangan Village, Polisiri Village, Bawen Sub District, Semarang Regency and Central Java. The drying process simulates when the open cut excavation process is exposed to sunlight, such as road excavations and bored pile excavations. The method used is testing the physical property, property of rocks and mechanical property with drying at intervals of 0 minute, 30minutes, 60minutes, and 90minutes. Initial condition of sample had 23 percent-31 percent of vulnerable water content. The influence of drying can reduce the value of water content; clay shale is really easy in creating the weathering; and all samples of shale clay have very low durability properties. Of all the UCS test samples, it can be said that the longer the drying, the greater the percentage of qu value loss. For testing Modulus Elasticity can be said that the longer the drying, the greater the percentage of loss of E50 value and Etan value. The relationship between UCS and Modulus Elasticity (E50 and Etan) values with the duration of the drying is the longer the drying the greater the lost value of UCS and Modulus Elasticity.

Limitation of exceptional construction sites, particularly due to fast growing of human population and economic development is common nowadays in Malaysia. Utilization of waste materials, which are lightweight, was one of the possible solutions that can be used to solve bearing capacity and settlement problems of embankments on soft compressible soil. It has been found that the utilization of tire shreds in highway construction offers economic and environmental benefits. Research focused on the determination of physical and engineering properties of stabilized cohesive frictional soils using shredded scrap tires. Laboratory tests according to British Standard 1377 were performed on untreated cohesive frictional soil, 100% shredded tire and mixtures of the soil and shredded tire by ratios of 90%-10%, 70%-30%, 50%-50%, 30%-70% and 10%-90%. Results show that admixtures of soil and shredded tires by ratio of 70%- 30% give highest improvement in term of shear strength parameters with 23%...

The currently applicable legal provisions and also the economic concepts emphasize the importance of circular economy. In this aspect, it is very important to reduce the waste production respectively planning and running a business. Technical research is the key to finding a new applications for waste, in particular disposed on landfilling. Mining and energy industries belong to the biggest producers of waste in Poland. The total share of these two branches in waste production is up to 70% (mining and quarrying 53%; electricity, gas, steam and air conditioning supplay 17%). In environment, economy and social aspect, it is very important to develop this waste. The paper presents research on the physico-mechanical properties of the aggregates based on colliery shale supplemented by fly ash (20%-40% supplement of fly ash). The following tests should be mentioned among performed: particle size distribution, the sand equivalent test, freeze resistance and direct shear tests. Also the chemical properties found in the literature was invoked. The research shows good physico-mechanical properties of the mixes, such as cohesion (44.62 kPa-68.57 kPa) or internal firiction angle (34.74°-40.52°). Though low resistance to weathering and a large susceptibility to frost heave (the mass loss after the freezing cycles is 76%) may limit its applicatin in road engineering. The sand equivalent tests were made only for aggregates. Tested materials shows usefulness for earthen structures. However, the research should be supplemented by chemical tests and also observations of the material properties changes as the effect of time. The research on the leachability of chemical pollutants, which will determine the acceptable share of ash in the mix, could be especially significant. The fact that fly ash contains a lot of sulphates and chlorides, which leach into the environment may pose a threat to living organisms.

Cyclic undrained triaxial tests were carried out on saturated and unsaturated loose specimens of three fine-grained materials. The results confirm that, as the saturation degree decreases, liquefaction resistance sharply increases. In the interpretation of results, the first step was the assessment of the reliability of the use of the 5% strain amplitude criterion to define the attainment of liquefaction. With this aim, the tests were analysed assuming that the soil behaves as an equivalent viscous material. It is shown that the characteristic values of viscosity defining the start and completion of liquefaction depend on soil grading, increasing as the coefficient of uniformity increases. The equivalent viscosity corresponding to a condition of double strain axial amplitude of 5% is fairly constant for all soils. Then, starting from the observation of the relationship between the final volumetric strain and the initial degree of saturation, a theoretical interpretation of the tests...

The cyclic behaviour of plain cylindrical concrete subjected to multidirectional compression was investigated experimentally. A total of 42 cylindrical concrete specimens from three different concrete mixes were tested. This test program was particularly focused on the strength and deformation aspects of the concrete response and the process of damage build-up. From this study, it was found that the most important response index for concrete subjected to cyclic loading was the history of damage accumulated in the microstructure which was measured in terms of volumetric strain. The degradation of the elastic stiflhess due to cyclic loads was found to be primarily a function of geometrical change and insensitive to the type of concrete considered. The comparison with the monotonic response of concrete which was also investigated in this study suggests that the cyclic nature of the load promotes damage build-up at faster rates than the monotonic loading, and the path-dependence in the ...

Continued from reverse side however, unlike many formulations, the consistency condition is automatically satisfied, and plays no role in determination of the plastic modulus. For the non-hardening version, KID depends solely on the current stress state, whereas with the hardening modification, stress history effects are manifested by the evolution of an independent hardening control surface. The developed model was used to successfully predict the stress-strain response of: 1) hollow cylinder data under different principal plane orientations, 2) expanding cavity (pressuremeter data), 3) cyclic conventional triaxial compression (CTC) results, and 4) a combination of loading, unloading, and hydrostatic compression. Further research of stress paths which replicate a moving wheel is recommiended.

Dynamic behavior of coarse granular soils is becoming increasingly important in design and analysis of geotechnical engineering problems. Naturally coarse-grained soils are widely present in many parts of the world such as Tehran, the capital city of Iran which is located in a seismic area. In order to understand the dynamic behavior of this soil, a series of undrained cyclic triaxial tests were performed on reconstituted samples. In this paper, cyclic strength of Tehran soil is evaluated considering the effect of membrane compliance on excess pore water pressure. The test results indicate that in general, by increase in cyclic deviatoric stress amplitude or cyclic stress ratio, the required number of cycles to failure decreases. Also, the maximum excess pore water pressure ratio (ru) approaches to one at failure which can be considered as the initial liquefaction in Tehran alluvium. The medium to high relative density of Tehran soil results in cyclic mobility and limited shear stra...

To improve the essential properties of soil, stabilization proved to be more significant in overcoming the limitations of the desired soil. The improvement of soil properties will not only enhance the mechanical properties rather it will help in preventing dust and erosion formation. In this study, a set of tests are carried out to examine the strength characteristics of subgrade soil blended with ethylene vinyl acetate (EVA) and cement. EVA contributes almost 14% mass to the global waste, requiring bigger lands for its disposal; therefore, in order to promote a green environment and to bring an economical waste management system, an investigation of using EVA in the soil stabilization techniques is attempted. Soil specimens are investigated with and without the inclusion of EVA and cement. For this purpose, EVA was mixed with soil at a percentage level of 3, 6, and 9% whereas the cement was mixed at a percentage level of 4, 6, and 8%. To examine the combined effects of EVA and ceme...

This paper presents the results of a series of cyclic triaxial tests carried out on sands with different index properties. Samples from three grain-size distributions of Izmir (Turkey) sand were tested under consolidated-undrained conditions. The tests were performed under two different effective confining pressure values (100 and 200 kPa). The relative densities of the specimens were 30 and 50 %. The results showed that the relative density plays a dominant role in the liquefaction behavior of the sand, whereas the confining pressure increase has greater effects on the stress-strain properties of the sand. It was observed that the relationship between the grain-size diameters and cyclic stress ratios of the sands would be more realistic. It was found that the pore water pressure generation curve falls outside the narrow band proposed by previous studies and a greater coefficient is required for the cycle ratio depending on the soil properties and test conditions. The shear moduli of the sands increased independently of the mean diameter with the relative density under a confining pressure of 100 kPa. Under a confining pressure of 200 kPa, the shear moduli increased with the uniformity coefficient of the sand. Increments in the relative density resulted in a slight increment of the shear moduli for the sands. The goal of the current study was to provide an understanding of the liquefaction and stress-strain behavior of Izmir sand, which represents the material of similar sites with loose alluvial sediments located in earthquake-prone areas found around the world.

The increased use of alternative materials, particularly streams of industrial byproducts in transportation construction is motivated by the need to optimize construction of sustainable pavements. Fly ash has mostly been used as an additive in various applications in transportation construction. This paper presents a study on the use of a fly ash product as the primary constituent, rather than an additive. A fly ash product was lightly treated with cement in one test series, with lime and an enzyme based liquid stabilizer in the second and third test series respectively producing lightly stabilised fly ash (LSFA) material. Testing was aimed at fit-forpurpose assessment of the LSFA material in terms of mechanical properties. This is work in progress. The results have shown that the LSFA can achieve shear strength and modulus values highly appropriate and fit for design application in low volume roads.

The results of a study with undrained cyclic triaxial and direct simple shear (DSS) tests on high-quality undisturbed samples obtained from large blocks of a soft marine Norwegian clay are presented. Several tests with different average shear stresses, shear stress amplitudes, loading frequencies, and sample geometries have been performed on block samples taken from different depths. In tests with small average shear stresses, failure occurred due to large shear strain amplitudes, while large permanent shear strains were observed in tests with higher average shear stresses. Diagrams quantifying the undrained cyclic strength, permanent shear strain, shear strain amplitude, and permanent pore-water pressure dependent on average shear stress, shear stress amplitude, and number of cycles have been developed based on the test results. The undrained cyclic strength was found strongly dependent on loading frequency. Block samples from shallower depth showed a somewhat higher undrained cycl...

This paper discusses a complex investigation to determine the microcrack closure and opening, with four different triaxial tests of a homogeneous isotropic limestone. Two of the researches were under drained conditions (deviatoric triaxial test and triaxial test with constantly increasing stress) and two of them were under undrained conditions (triaxial test connected with decreasing confining pressure and triaxial test with constantly increasing stress). During the tests the uniaxial and the confining pressure, the pore-fluid pressure, and the axial and the lateral strains were measured continuously. ZUSAMMENGFASSUNG: In diesem Artikel wird eine komplexe Experimentenserie zur Bestimnung der Schliessung und Öffnung von Mikrospalten dargestellt, die aus vier verschiedenent auf homogenem isotropem Kalkstein ausgeführten triaxialen Untersauchungen besteht. Zwei von diesen Experimenten waren drainiert (erstens eine deviatorisch-triaxiale Unterschuchung, zweitens eine triaxiale Untersuchung mit ständig wachsender Spannung), undzwei waren undrainiert (eine triaxiale Untersuchung in Bezug auf abnehmenden Seitendruck und eine triaxiale Untersuchung mit ständig wachsender Spannung). Während der Experimenten wurden der uniaxiale und der Seitendruck, der Porenflüssigkeitsdruck und die axialen und lateralen Deformationen stets gemessen.

Traditional theoretical and experimental investigations of the mechanical behavior of granular media such as sand are restricted by the limited quantitative information about what actually happens internally. The discrete element method (DEM) was developed as a technique to examine the micromechanics of granular media for this purpose. In this paper, a new microscopic parameter in terms of redundancy factor is proposed to describe liquefaction for sand, and the evolution of redundancy factor is provided using DEM simulations under undrained conventional triaxial conditions. It is demonstrated that the phase transition dividing the soild-like behavior and liquid-like behavior is associated with a redundancy factor of 1, which corresponds to an average coordination number slightly above 4.

The cantilever-type local deformation transducer (cantilever-LDT) was developed as an alternative local axial strain measurement device for triaxial testing. The transducer behaves as a cantilever beam and the deflection at its free-end is measured by the output from the strain gages attached near the fixed-end. By placing two cantilever-LDTs along the same vertical alignment but at different levels of a specimen, the local axial strain is obtained from the relative movements of two cantilever-LDTs. The advantages over the original-LDT proposed by Goto et al. (1991) are: (i) a linear calibration curve, (ii) capability to release itself at large strains, and (iii) larger working range. With a gage length of 50 mm, the resolution, accuracy, and working range are 0.0012 %, 0.003 %, and 6 %, respectively. The triaxial test results on heavily overconsolidated clay specimens show that the cantilever-LDT can be used satisfactorily to measure the local axial strain accurately, but the reliability depends very much on the quality of specimen preparation and setup.

The effects of initial soil fabric on behaviors of granular soils are investigated by using Distinct Element Method (DEM) numerical simulation. Soil specimens are represented by an assembly of non-uniform sized spheres with different initial contact normal distributions. Isotropically consolidated triaxial compression loading and extension unloading in both undrained and drained conditions are simulated for vertically-and horizontally-sheared specimens. The numerical simulation results are compared qualitatively with the published experimental data and the effects of initial soil fabric on resulting soil behaviors are discussed, including the effects of specimen reconstitution methods, effects of large preshearing, and anisotropic characteristics in undrained and drained conditions. The effects of initial soil fabric and mode of shearing on the quasi-steady state line are also investigated. The numerical simulation results can systematically explain that the observed experimental behaviors of granular soils are due principally to their conditions of the initial soil fabric. This outcome provides insights into the observed phenomena in microscopic view.

Laboratory tests were conducted to study the effect of waste plastic chips derived from used PET bottles on the strength and swelling potential of silt. The content of plastic waste was varied from 0, 0.5, 0.75 and 1 % by dry weight of silt. The size of waste plastic chips was 15 mm x 5 mm in the study. The results of this study reveal that there is significant improvement in the strength silt and considerable reduction in swell pressure with the inclusion of small quantity of waste plastic chips. Mitigation of expansive soils using waste plastic chips can be a good solution to reduce the swell potential of silt on which buildings and roads are going to be constructed

Because there are more used car tyres produced each year, disposing of them has become a significant environmental issue on a global scale. Utilizing used tyres will reduce the effect on the environment and increase resource preservation. The stabilisation of soils using CRP (5%, 10%, 15%) is discussed in this article. The conduct and effectiveness of the stabilised soil were evaluated using the soil properties, compaction, California bearing ratio (CBR), and direct shear test. When soil and CRP are combined, it is seen that the maximum dry density and ideal moisture content decline as the percentage of crumb rubber in the soil increases. Bearing capacity and tensile strength are barely affected by blending. Nevertheless, the numbers stayed within reasonable bounds.

Limitation of exceptional construction sites, particularly due to fast growing of human population and economic development is common nowadays in Malaysia. Utilization of waste materials, which are lightweight, was one of the possible solutions that can be used to solve bearing capacity and settlement problems of embankments on soft compressible soil. It has been found that the utilization of tire shreds in highway construction offers economic and environmental benefits. Research focused on the determination of physical and engineering properties of stabilized cohesive frictional soils using shredded scrap tires. Laboratory tests according to British Standard 1377 were performed on untreated cohesive frictional soil, 100% shredded tire and mixtures of the soil and shredded tire by ratios of 90%-10%, 70%-30%, 50%-50%, 30%-70% and 10%-90%. Results show that admixtures of soil and shredded tires by ratio of 70%- 30% give highest improvement in term of shear strength parameters with 23%...

Tire-soil mixtures can be used as good construction materials in many geotechnical engineering applications such as pavement foundations, lightweight fill in road embankments and lightweight backfill behind retaining walls. This paper describes research undertaken to investigate experimentally the impact of shredded rubber tires as reinforcing material on the mechanical properties of cement-stabilized soft clay, in terms of strength and stiffness. A series of laboratory experiments are carried out on cement-stabilized clay mixed with several portions of shredded rubber tires of sizes 440 µm and 4 mm. The tests conducted include compaction, unconfined compression strength and indirect tensile strength. The results demonstrate that the use of shredded rubber tires has a potential in enhancing the ductility of cementstabilized soft clay but decreases stiffness and ultimate resistance.

Limitation of exceptional construction sites, particularly due to fast growing of human population and economic development is common nowadays in Malaysia. Utilization of waste materials, which are lightweight, was one of the possible solutions that can be used to solve bearing capacity and settlement problems of embankments on soft compressible soil. It has been found that the utilization of tire shreds in highway construction offers economic and environmental benefits. Research focused on the determination of physical and engineering properties of stabilized cohesive frictional soils using shredded scrap tires. Laboratory tests according to British Standard 1377 were performed on untreated cohesive frictional soil, 100% shredded tire and mixtures of the soil and shredded tire by ratios of 90%-10%, 70%-30%, 50%-50%, 30%-70% and 10%-90%. Results show that admixtures of soil and shredded tires by ratio of 70%- 30% give highest improvement in term of shear strength parameters with 23%...

Traditional approaches to measure risk to natural hazards considers the use of composite indices. However, most of the times such indices are built assuming linear interrelations (interdependencies) between the aggregated components in such a way that the final index value is based only on an accumulative or scalable structure. In this paper we propose the use of Fuzzy Inference Systems type Mamdami in order to aggregate physical seismic risk and social vulnerability indicators. The aggregation is made by establishing rules (ifthen type) over the indicators in order to get an index. Finally a quantitative seismic risk estimation is made though the convolution of these two main factors by means of fuzzy inferences, in such a way that no linear assumptions are used along the estimation. We applied the fuzzy model over the city of Bogota Colombia. We consider that this approach is a useful way to estimate a measure of an intangible reality such as seismic risk, by assuming the urban se...

Coarse aggregate is widely used in the unbound granular layers (UGM) of roads, in particular as granular sub-base and base. However, although various studies have been conducted on these materials, their mechanical behaviour still has not been properly characterized, in Portuguese conditions, especially due to reasons connected to the heterogeneity of the rock masses from which they come from. This has special importance for Portuguese pavement technology. In the attempt of contributing for a better knowledge of that behaviour, a work was developed having the aim of obtain the mechanical characterization and the establishment of behaviour models for crushed materials coming from different lithologies, namely limestone and granite, susceptible of being used as UGM. This paper describes the principal results obtained from the work and pointing out the main directives that can be extracted from it, in terms of the global behaviour of a road pavement. USED MATERIALS The materials used in these work were limestone and granite, Figure 1. They were characterized 5 samples of crushed limestone, from Pombal, centre of Portugal, and 3 samples of crushed granite, 2 of them outcrops near Celorico da Beira and the 3rd near Braga, interior centre and north of Portugal.

The influence of compactor footprints on the constitutive response of clayey sand subgrade soil was investigated. Three footprint types--flat base, cylindrical protrusion, and pyramid frustum protrusion--were examined using triaxial tests and pavement model tests under dynamic loading. First, each block sample was prepared using the compactor of certain footprint. The triaxial specimens were trimmed from the block sample at different orientations to represent the rotation of the principal stress direction. The results show significant variations in the responses. Samples compacted by the compactor with pyramid frustum protrusion base showed the highest lateral stiffness, followed by samples compacted with cylindrical protrusion, and finally those compacted with the smooth footprint. However, samples compacted with the flat base showed the stiffest response in the vertical direction. The subgrades of the pavement models were each compacted to the same density using compactors with di...

This paper presents the development of a method using local deformation transducers (LDTs) to locally and sensitively measure small axial and lateral strains in soil in a compression test. A local strain measurement system comprising of axial and lateral LDTs was developed referring to the original LDT system and the cantilever LDT system, respectively. The LDTs were calibrated both in air and under water. Their insensitivity to pressurized water was confirmed. The calibration factors for the axial and lateral LDTs were found to be 1.695 mm/volt and 1.001 mm/volt, respectively. The performance in terms of repeatability and stability of the LDT system was evaluated. The repeatability test showed that the average standard deviation of the lateral LDT was 0.015 volt, while the stability test showed that the average standard error of the axial and lateral LDT were 3.13 × 10-5 volt and 2.65 × 10-5 volt, respectively. Unconfined compression tests were conducted on three reconstituted clay samples to examine the proposed axial and lateral LDT system. The stress-strain relationship indicates a nonlinear relationship between the axial and lateral strain of soil instead of the conventionally assumed constant relationship. The results demonstrate this nonlinear behavior even at small strain levels, which were successfully measured using a domestically built axial and lateral LDT system.

The paper presents laboratory test results on hydraulically bound road foundation materials containing high volume of; limestone, steel slag (SS) and granulated blast furnace slag (GBS) dust compared with Type 1 sub base materials normally used by road engineers in the UK as a foundation layer with or without capping. The mixtures incorporating waste dusts were designed as potential hydraulically bound road pavement foundation layer and contain in addition to the dust in the control sub base the following percentage of dust: i) 20% limestone dust, ii) 20% SS dust, iii) 20% limestone dust + 5% GBS and iv)20% SS dust + 5% GBS. The size of the dust aggregates range from 0-4mm. The addition of the wastes dust was to enhance the stiffness of the road foundation materials, save primary aggregates and hence reduce the cost of road construction. The unbound and lightly bound materials resilient modulus were predicted using triaxial repeated load tensile tests according to the current Europe...

ABSTRACT: Oil sands are natural deposits of sand materials that are rich in bitumen. Limited studies have been conducted to determine the dynamic behavior of oil sand materials. Recent difficulties encountered in oil sand mine fields in Canada substantiated the need to characterize the stress dependent, visco-elastic and plastic behavior of oil sand materials under dynamic loading of off-road construction and mining equipment. This paper introduces a new cyclic triaxial test procedure for determining shear modulus and deformation characteristics of oil sand materials. The test procedure was used to characterize shear moduli of three oil sand materials with varying bitumen contents. From the test results, nonlinear shear modulus models were successfully developed to characterize temperature and stress dependent behavior of the tested oil sand materials. The research findings indicate that the new laboratory approach is an improvement on conventional tests especially when oil sand mat...

A huge network of rural roads is being developed in India under the most ambitious Prime Minister's rural connectivity programme, PMGSY (Pradhan Mantri Gramin Sadak Yojna). Under this programme, thousands of kilometers of rural roads are being constructed in the country, which require good quality pavement materials like crushed stone. The scarcity of natural aggregates has compelled to use marginal materials or locally available soils in structural layers of these pavements, which would reduced the cost of the project. Granular lateritic soils are widely available in many parts of India and presently, this is also used as sub-base material in different rural road projects, where it satisfies the code specifications. However, granular lateritic soils of some locations do not satisfy the strength and plasticity requirement of sub-base layer. But, they can probably be made suitable through stabilization. Though stabilization of soil by cement or lime is a well known process of improving the strength and stability of soil, the strength and stiffness parameters of stabilized lateritic soils in terms of modulus of rupture, resilient modulus, flexural modulus have very limited reference in literature. Therefore, in this study an attempt has been made to characterize the cement stabilized lateritic soils for use in sub-base and base layers in rural road pavements. A comprehensive laboratory testing programme has been conducted on cement stabilized granular lateritic soil samples collected from five different places of eastern India to study various strength parameters such as compressive strength, modulus of rupture and stiffness properties in terms of flexural modulus of cement stabilized granular lateritic soil. In this paper, strength and stiffness developments of cement stabilized granular lateritic soil in 7 days and 28 days have been studied and its suitability as a structural layer in rural roads has been investigated. Suitable modulus values of cement stabilized granular lateritic soils have been proposed which can be used as an input parameter for the input in mechanistic design of roads. Also relationships have been proposed to determine modulus of rupture and flexural modulus of cement stabilized granular lateritic soil from its compressive strengths.

New developments in unexplored areas in the Suez Canal region in Egypt have disclosed the shortage of data required for analysis of problems involving static and dynamic loading. Monotonic triaxial compression tests were performed to evaluate the shear strength properties of the sand located in this area. Characteristic state and phase transformation lines were not identical and were independent of soil density. Dynamic properties at small and medium strain levels were evaluated through resonant column and cyclic triaxial tests, respectively. Effects of effective confining stress and relative density on dynamic properties were investigated. Upon cyclic loading, number of cycles to reach failure increased as the relative density and effective confining stress increased. The shear modulus increased as the relative density and effective confining stress increased in small and medium strain ranges. Torsional damping coefficient decreased as the effective confining stress increased, and was not significantly affected by the relative density.

Clay shale has unstable properties even though it is on a slope having a gentle slope. This raises many geotechnical problems. This study aims to determine the effect of clay shale drying on compressive strength and durability reduction by using samples taken from Kandangan Village, Polisiri Village, Bawen Sub District, Semarang Regency and Central Java. The drying process simulates when the open cut excavation process is exposed to sunlight, such as road excavations and bored pile excavations. The method used is testing the physical property, property of rocks and mechanical property with drying at intervals of 0 minute, 30minutes, 60minutes, and 90minutes. Initial condition of sample had 23 percent-31 percent of vulnerable water content. The influence of drying can reduce the value of water content; clay shale is really easy in creating the weathering; and all samples of shale clay have very low durability properties. Of all the UCS test samples, it can be said that the longer the drying, the greater the percentage of qu value loss. For testing Modulus Elasticity can be said that the longer the drying, the greater the percentage of loss of E50 value and Etan value. The relationship between UCS and Modulus Elasticity (E50 and Etan) values with the duration of the drying is the longer the drying the greater the lost value of UCS and Modulus Elasticity.

Purpose In triaxial test, a rubber membrane encloses the specimen. The membrane is specifically thin to a thickness of no influence on the test results. However, testing coarse-grained materials in triaxial test might be challenging due to the occurrence of membrane punching. In trial tests, the angular aggregate easily punches the membrane. Methods A technique was explored to mitigate membrane punching due to sharp edges of angular materials. One method has filter paper inserted between two membranes and another method has aluminium foil instead of filter paper. Results The use of filter paper and aluminium foil as insert materials is successful in preventing the membrane punching. Consequently, the filter paper is not contributing to additional resistance when used as protection between two membranes as compared to aluminium foil. Conclusion This paper investigates the performance of the protection materials by experiments. Essentially, the filter paper had no significant effect on test results; this fact was verified through numerical modelling and comparative tests by using rounded particles material.

Objetivo: determinar la prevalencia de las alteraciones de la visión al color y visomotoras en un grupo de niños en edades entre cinco y quince años, en las localidades de Fontibón, Puente Aranda y Usaquén en Bogotá. Metodología: se realizó un estudio observacional descriptivo en 243 pacientes que estudiaban en colegios representativos de cada localidad. A cada niño se le aplicaron los test de integración visomotora (vmi), Ishihara y Farnsworth. El análisis estadístico se realizó por medio de tablas de contingencia y ji2 (c2). Resultados: la prevalencia de las alteraciones en la visión al color fue de 6,7 % (6/89 test de Ishihara) y 14,6 % (13/89 test de Farnsworth) para el colegio España de Puente Aranda; 2,4 % (2/84 test de Ishihara), y 4,8 % (4/84 test de Farnsworth) para el colegio Pablo Neruda de Fontibón, y 2,9 % (2/70 test de Ishihara) y 10 % (7/70 test de Farnsworth) para el colegio de La Salle de Usaquén. La prevalencia de disfunciones visomotoras fue de 55,1 % (49/89) para...

h i g h l i g h t s Utilizing tire wastes in geotechnical applications is a reasonable way to reduce stockpiles of disposed tires. Shredded waste tires can be used as a partial substitution for stone column materials. Using long planar shape tire shreds improves the axial bearing capacity of stone column by 30%. Results lead to reusing tire waste, improvement in stone columns performance and a decrease in construction costs.

Shearing or compression of granular materials causes particles to translate and rotate relative to each other, interlock or fracture depending on their mineralogy, morphology, porosity, applied stresses and boundary conditions. Conventional soil plasticity theories consider mainly the stress level and density to predict soil failure and ignore the influence of particle fracture. However, recent research has shown that there is a strong relationship between granular particle fracture and plastic yielding and hardening. In this study, the fracture of individual silica sand particles was modelled by adopting the bonded particle model concept within the framework of the discrete element method (DEM). Individual three-dimensional (3D) particles were generated as an agglomerate of a large number of small spherical sub-particles that were connected by parallel bonds that resist moment and tension at contact points. The tensile strength variation observed when testing natural silica sand wa...

This research studied the effect of two enzymes as soil stabilizers on two soil types to determine how and under what conditions they function. Researchers evaluated the chemical composition, mode of action, resilient modulus, and shear strength to determine the effects of the enzymes A and B on the soils I and II. The enzymes produced a high concentration of protein and observations suggest the enzymes behave like a surfactant, which effects its stabilization performance. The specimens were subjected to testing of varying lengths of time to determine their performance. Researchers observed an increase in the resilient modulus as the curing time increased but that an increase in application rate, as suggested by manufacturers, did not improve the performance of the enzymes. The study also suggests noticeable differences between the two enzymes and their effects on the soils in terms of resilient modulus and the stiffness of the soil.