Pore Water Pressure

The paper describes the results of field tests carried out using highly instrumented piles at a very soft estuarine clayey silt deposit at Kinnegar, Belfast. The site has been used for a number of years as a geotechnical test bed site and has been comprehensively characterised using both in-situ tests including Cone Penetration Tests (CPT) and by means of an extensive laboratory test program. The instrumented pile used in the investigation was developed at University College Dublin and includes sensors which allow readings of both total radial stress and pore pressure during installation, equalisation and load testing to be made at a number of locations along the pile shaft. The radial stress and pore pressure developed during installation and equalisation are discussed in terms of the CPT q cnet value and compared with similar results from the literature.

La Sorbella" is a deep-seated existing landslide in a Miocene clayey formation located in central Italy. Given the interaction with a national road, this landslide has been monitored for a long time with inclinometers and hydraulic piezometers. Recently, the monitoring system was implemented by adding pressure transducers in the Casagrande cells and by equipping the old inclinometers with in-place probes, to allow a remote reading of the instruments and data recording. This system allowed to identify that the very small average rate of movement observed over one year (1.0-1.5 cm/year) is the sum of small single sliding processes, strictly linked to the sequence of rainfall events. Moreover, data recorded by in-place inclinometer probes detected the response of the landslide to the seismic sequence of 2016 occurring in central Italy. Such in situ measurements during earthquakes, indeed rarely available in the scientific literature, allowed an assessment of the critical acceleration of the sliding mass by means of a back-analysis. The possibility to distinguish the difference between seismic and rainfall induced displacements of the slope underlines the potential of continuous monitoring in the diagnosis of landslide mechanisms.

Climate change with a higher amount of rain during harvesting increases the need for efficient harvesting and transport which leads to use of more effective and heavier machinery with an enhanced risk for compaction. Soil compaction is known to reduce the production capacity of a soil and can have severe negative ecological consequences and may reduce the production capacity of soils. Heavy loads can enhance subsoil compaction which is considered to be irreversible. The effect of contrasting wheeling frequency (1x; 10x) and different wheel loads on the bearing capacity of a silt soil was studied in cooperation project between NIBIO (Norway), Christian- Albrecht- Universitat Kiel (Germany) and Norwegian University of Life Sciences (Norway). Furthermore it is examining the influence of the use of typical (Norwegian) transport equipment (cereals, potatoes) with differing loads (12Mg; 16Mg total weight) and inflation pressure on soil physical parameters and yields under the climatic con...

Liquefaction during earthquakes can result in severe damage to structures, primarily from excess pore water pressure generation and subsoil softening. Deep Soil Mixing (DSM) is a common method of soil improvement and is also used to reduce shear stress in lique able soils to control liquefaction. The current study evaluated the e ect of DSM columns and the implementation of di erent column patterns on controlling liquefaction and decreasing settlement of shallow foundations. A series of shaking table physical modeling tests were conducted for three di erent distribution patterns of DSM columns (i.e., square, triangular, and single) with a treatment area ratio of 30%. The treatment was applied to a lique able soil under a shallow model foundation. The results showed that the excess pore water pressure decreased by 20% to 50% in comparison with the unimproved soil, depending on the DSM column pattern used. For improved soil, the shallow foundation settlement was about 10% more than that of the unimproved soil in the best case. Increase in soil shear sti ness after the use of the DSM columns was compared with the results of existing practical relations to increase soil shear strength.

Long-term cyclic loading is observed in a wide range of human activities, as well as in nature, such as in the case of ocean waves. Cyclic loading can lead to ratcheting which is defined as progressive accumulation of plastic deformation in a material. Long-term cyclic loading causes a time effect (creep), which is a secondary compression effect. In this article, we conducted 15 triaxial tests on four types of cohesive materials in undrained conditions to evaluate the damage and failure mechanism. To characterize the strain and pore pressure development, we modified the Yanbu resistance concept. On the basis of the static creep tests, we concluded that the stress paths for undrained creep behavior have to take into account the pore pressure developed during long-term cyclic loading. Pore pressure build-up and plastic strain accumulation during long-term cyclic loading are dependent on the number of loading cycles. Finally, we proposed the failure criterion, which was based on the Modified Cam-Clay constitutive model.

The mechanism of cohesive soils response to cycling loading is less investigated compared to cohesionless soils. Multiple load-unload cycles cause significant changes in the structure of cohesive soils, which result in complex behaviour under the given load. The aim of the paper was to investigate and study the influence of load frequency on cohesive soil reaction. In order to obtain results, tests were conducted using the cyclic triaxial apparatus. Three cyclic tests were carried out, each for different frequency -0.5 Hz, 1.0 Hz, 2.0 Hz and one static triaxial test. The maximal value of deviator stress q max , used in the cyclic tests, was set to 40 kPa. Afterwards samples were unloaded to q min = 30 kPa. Cyclic loading triaxial tests were performed in a consolidated-undrained (CU) one-way loading manner, a sinusoidal waves were used. After the cycling loading was completed, a static triaxial shear test was conducted. Changes in the cohesive soil responses depending on cycling load frequency were presented in the paper. Differences in the accumulation of plastic strains were noticed, as well as changes of degradation index values, resilient degradation index values and differences in the excess pore water pressure development.

Cohesive soils subjected to cyclic loading in undrained conditions respond with pore pressure generation and plastic strain accumulation. The article focus on the pore pressure development of soils tested in isotropic and anisotropic consolidation conditions. Due to the consolidation differences, soil response to cyclic loading is also different. Analysis of the cyclic triaxial test results in terms of pore pressure development produces some indication of the relevant mechanisms at the particulate level. Test results show that the greater susceptibility to accumulate the plastic strain of cohesive soil during cyclic loading is connected with the pore pressure generation pattern. The value of excess pore pressure required to soil sample failure differs as a consequence of different consolidation pressure and anisotropic stress state. Effective stresses and pore pressures are the main factors that govern the soil behavior in undrained conditions. Therefore, the pore pressure generated in the first few cycles plays a key role in the accumulation of plastic strains and constitutes the major amount of excess pore water pressure. Soil samples consolidated in the anisotropic and isotropic stress state behave differently responding differently to cyclic loading. This difference may impact on test results analysis and hence may change the view on soil behavior. The results of tests on isotropically and anisotropically consolidated soil samples are discussed in this paper in order to point out the main features of the cohesive soil behavior.

Cohesive soils subjected to cyclic loading in undrained conditions respond with pore pressure generation and plastic strain accumulation. The article focus on the pore pressure development of soils tested in isotropic and anisotropic consolidation conditions. Due to the consolidation differences, soil response to cyclic loading is also different. Analysis of the cyclic triaxial test results in terms of pore pressure development produces some indication of the relevant mechanisms at the particulate level. Test results show that the greater susceptibility to accumulate the plastic strain of cohesive soil during cyclic loading is connected with the pore pressure generation pattern. The value of excess pore pressure required to soil sample failure differs as a consequence of different consolidation pressure and anisotropic stress state. Effective stresses and pore pressures are the main factors that govern the soil behavior in undrained conditions. Therefore, the pore pressure generated...

With an average annual rainfall in the range 1200mm 1800mm, landslides in Wollongong are triggered by periods of prolonged heavy rainfall. During such events, real-time pore water pressure, slope movement and rainfall data can be extremely useful for risk assessment and emergency management. A network of continuously monitored real-time landslide field stations has been established in Wollongong. This network will facilitate risk management operations, enhance our understanding of landslide triggering mechanisms and improve quantitative assessment of landslide hazard. Four stations have been established and additional stations are proposed. Data collection and management is fully automated yet manually accessible as required. The major benefit of this system is the accessibility and availability of fully automated graphical output via the web immediately as the data is received from the field stations. The widespread accessibility of this information in near real-time has clear bene...

Quantitative risk assessment should complement, if not replace qualitative assessments as the preferred approach for hazard and risk assessment and management of land instability. Therefore, a comprehensive Landslide Risk Management Procedure has been proposed in this thesis. In a significant step towards a quantitative approach for risk assessment, a hazard ranking of 328 documented landslide sites within the study area has been achieved during this research project. This hazard ranking of existing landslides is considered to be unique and the first quantitative landslide hazard assessment in Australia. A n e w series of geology and land instability maps has been prepared, the Geotechnical Landscape M a p Series (GLMS). These maps have been produced using the Wollongong City Council's ( W C C ) Geographic Information System computer package. The maps can be easily updated as new information becomes available. A total of 328 sites of land instability have been documented in a landslide inventory of the study area. A Site Reference Code numbering system has been used to identify the sites of instability. The inventory comprises of two separate but essential and interrelated components: • a land instability m a p record, one m a p layer of the Geographic Information System computer package based Geotechnical Landscape M a p Series • a computer-based database summarising 60 aspects of each site of land instability. The G L M S and the accompanying Land Instability Database will provide a greatly improved graphical representation and database of geology and land instability hazards within the local government area. The importance of this information as a land management tool cannot be overstated. The excellent results achieved in the production of the G L M S and a subsequent spatial analysis of the geology and landslide areas confirms the viability and resourcefulness of the GIS computer package for this project. This thesis is not only concerned with the spatial distribution of landsliding within the study area, but also with recurrences of instability over time. Therefore, the analysis of historical recurrences as well as that of recorded shear movements at depth has been undertaken in relation to detailed rainfall records. A unique an innovative procedure has been developed which calculates the percentage exceedance (determined using a base 20 year period of daily rainfall) of

This paper describes the monitoring of several existing landslides in an urban area near Wollongong in the state of New South Wales, Australia. A brief overview of topography and geology is given and reference is made to the types of slope movement, processes and causal factors. Often the slope movements are extremely slow and imperceptible to the eye, and catastrophic failures are quite infrequent. However, cumulative movements at these slower rates do, over time, cause considerable distress to structures and disrupt residential areas and transport routes. Inclinometers and piezometers have been installed at a number of locations and monitoring of these has been very useful. The performance of instrumentation at different sites is discussed in relation to the monitoring of slope movements and pore pressures. Interval rates of inclinometer shear displacement have been compared with various periods of cumulative rainfall to assess the relationships.

A stone column is one of the soil improvement methods that are mainly used for improving the geotechnical behavior of soft soils. For deep improvement of soft soil, the floating stone columns are considered the best and effective economically which provide lateral confinement and drainage and longitudinal skin friction. In this study, six tests were carried out on the natural soft soil of undrained shear strength of 5.5 kPa improved by single and two linear distributed floating stone columns. The stone column dimensions are 30 mm in diameter and 180 mm in length and the stone column material is sand of high internal friction angle of 48°. The natural and improved soil samples are tested under isolated raft foundation of dimensions 120×120 mm subjected to vertical static and cyclic loading of frequency 2Hz and continued for 50 seconds. The results showed a significant improvement in soil bearing capacity when reinforced with stone columns despite the small area replacement ratio, where the bearing capacity of improved soil increased by 120 to 145%. The compressibility of improved soil decreased by 57 to 86% in comparison with that of natural soft soil. Also, the floating stone columns reduced the porewater pressure, where the stone columns considered efficient in providing short drainage pathways. This can be one of the reasons why soil reinforced with floating stone columns hold higher cyclic and static stresses regardless the end bearing of stone columns.

Presented in this paper is a study on the lateral unloading creep tests under different excess pore water pressures. The marine sedimentary soft soil in Shenzhen, China, was selected in this study. The results show that the excess pore water pressure plays a significant role in enhancing the unloading creep of soft soil. Higher excess pore water pressure brings more obvious creep deformation of soft soil and lower ultimate failure load. Meanwhile, the viscoelastic and the viscoplastic modulus of soft soil were found to exponentially decline with creep time. A modified merchant model and a combined model of the modified merchant model and plastic elements are used to simulate the viscoelastic and the viscoplastic deformation, respectively. Therefore, a lateral unloading creep model of soft soil is developed based on the modified merchant model. The accuracy and applicability of this model were verified through identifying the parameters in the model. Research results are of particula...

The unloading creep behavior of soft soil under lateral unloading stress path and excess pore water pressure is the core problem of time-dependent analysis of surrounding rock deformation under excavation of soft soil. The soft soil in Shenzhen, China, was selected in this study. The triaxial unloading creep tests of soft soil under different initial excess pore water pressures (0, 20, 40, and 60 kPa) were conducted with the K0 consolidation and lateral unloading stress paths. The results show that the unloading creep of soft soil was divided into three stages: attenuation creep, constant velocity creep, and accelerated creep. The duration of creep failure is approximately 5 to 30 mins. The unloading creep behavior of soft soil is significantly affected by the deviatoric stress and time. The nonlinearity of unloading creep of soft soil is gradually enhanced with the increase of the deviatoric stress and time. The initial excess pore water pressure has an obvious weakening effect on ...

The paper examines the effect of small percentages of bentonite on pore pressure generation in loose sands, from small strains all the way to liquefaction. It relies on resonant column, static triaxial and cyclic triaxial tests conducted on specimens prepared by dry-mixing Ottawa sand and bentonite, at a skeleton relative density of 35% ± 5%. Two main variables are investigated: the percentage of bentonite (3% and 5% by dry mass of the sand), and the duration of the ageing period preceding shear (1 to 10 days). The presence of bentonite increases the shear strain needed to initiate the generation of excess pore pressures in resonant column tests; in cyclic tests it reduces the mean pore pressure generated per loading cycle and allows the specimen to sustain an increased loss of effective stress before liquefaction initiates, both effects contributing to an increased resistance to liquefaction. These effects are further enhanced with prolonged pre-shear ageing. Additionally, under st...

The resistance of dike materials has a great effect on the development of hydraulic engineering around the world. It helps to understand the mechanism of dike failure occurred due to the influence of hydraulics and Geotechnical parameters. The overtopping moment is one of the main failures that reduces the stability of the dike embankment through initiating the breach channel inside dike crest as a result of water flow above the downstream slope of the dike. Two spatial overtopping tests were conducted at in Hydraulic Geotechnical laboratories at the University Sains of Malaysia to observe the evolution of matric suction and volumetric water content for two soil types of sand and very silty sand soils. A pilot channel was cut in dike crest along the side wall of the small flume channel to represent the transition water flow from upstream into downstream slopes during overtopping test. The results indicated that the matric suction decreases due to the increase of volumetric water con...

Rainfall is one of the most important triggers of slope failure. Weathered pyroclastic (tephra) 2 deposits are especially vulnerable to slope failure because they commonly form slopes of high 3 porosity and high clay content. Empirically-derived thresholds for the triggering of landslides 4 are commonly based on rainfall conditions and have been widely applied in volcanic soils. However, so far only few researchers utilized pore water pressure in the slope as additional 6 variable for the threshold calibration. Here we derived a new rainfall threshold for initiating the 7 decrease in effective stress in the slope by analyzing a long-term record of rainfall and piezom-8 eter data from a slide-prone coastal area in northern New Zealand that consists of clayey, hal-9 loysitic tephra deposits. The level of effective stress decrease increases with rainfall intensity 10 and duration. We observed highest effective stress decrease of up to 36 % during rainfall events 11 that triggered landslides in our study area. The effective stress threshold exhibits a satisfactory 12 predictive capability. The probability of correctly predicting a decrease in effective stress is 13 53 %. The effective stress threshold contributes towards the implementation of the decrease in 14 effective stress into rainfall thresholds for the occurrence of landslides. 15 16 Keywords landslides; rainfall threshold; effective stress; weathered tephra; spheroidal hal-17 loysite; rainfall-induced slope failure 18 19 et al., 2018a). In their recent review, Segoni et al. (2018a) summarized that most rainfall thresholds were 46 derived for shallow landslides and debris flows, whereas only few rainfall thresholds for deep-seated 47 landslides, rockslides, and earthflows had been studied. Furthermore, Segoni et al. (2018a) recognized 48 that most studies solely rely on rainfall data when calibrating rainfall thresholds. They found only two 49 case studies -Baum and Godt (2010) and Napolitano et al. (2016)in which pore water pressure data 50 provided additional insight into the trigger mechanism of landslides. Understanding changes in pore 51 water pressure due to rainfall is needed to calculate changes in effective stress in the soil slope (Duncan 52 et al., 2014) and its evaluation would therefore offer a new beneficial perspective in the determination 53 of rainfall thresholds (Segoni et al., 2018a). 54 55 1.1 Suitability of study area 56

In the Tauranga region sensitive soil failures commonly occur after heavy rainfall events, causing considerable infrastructure damage. Several notable landslides include a large failure at Bramley Drive, Omokoroa in 1979, the Ruahihi Canal collapse in 1981, and numerous landslides in May 2005; recently the Bramley Drive scarp was reactivated in 2011. These failures are associated with materials loosely classified as the Pahoia Tephras -a mixture of rhyolitic pyroclastic deposits of approximately 1 Ma. The common link with extreme rainfall events suggests a pore water pressure control on the initiation of these failures. Recent research on the structure of the soils shows a dominance of halloysite clay minerals packed loosely in arrangements with high porosity (51 -77 %), but with almost entirely micropores. This leads us to conclude that the permeability is very low, and the materials remain continuously wet. The formation of halloysite is encouraged by a wet environment with no episodes of drying, supporting this assumption. A high-resolution CPT trace at Bramley Drive indicates induced pore water pressures rising steadily to a peak at approximately 25 m depth; this depth coincides with the base of the landslide scarp. We infer that elevated pore water pressures develop within this single, thick aquifer, triggering failure through reduced effective stresses. The inactive halloysite clay mineral results in low plasticity indices (13 -44 %) and hence high liquidity indices (1.2 -2.4) due to the saturated pore space; remoulding following failure is sudden and dramatic and results in large debris runout distances.

Different types of pockmarks, including single pockmarks, circular pockmarks, elongated pockmarks, chain-type pockmarks, and compound pockmarks, were identified in coastal areas around Fujian, China. The sediments associated with pockmarks were mainly silty clay to clay, with a small quantity of silt with fine sand. The sulfate content in the pore water in the sedimentary layers associated with pockmarks decreased with depth from the surface, whereas the free methane content increased with depth. The interaction between sulfate and methane is well known, but differences in the sulfate–methane transitional zone (SMTZ) were observed in different areas with different hydrologic characteristics. The sedimentary SMTZ of the offshore Zhe-Min mud wedge was shallow, at 50–70 cm below the seafloor. The sedimentary SMTZ was moderately deep (90–115 cm) in the central bay area and deep (180–200 cm) in the sandy area offshore. This variability in SMTZ depth reflects different amounts of free met...

Dike construction has been widely used because of its potential to protect people and properties from overtopping flows. Water levels may exceed a dike crest and cause overtopping flow during high river discharge. This phenomenon has caused serious damage to the dike body due to the reduction of soil shear strength. The increase of water content within particles and its relationship with the development of breach channel failure in downstream and upstream slopes are affected by a series of geotechnical and hydraulic aspects. Transient seepage and slope stability analyses (FOS) were performed in this study using 2D finite element methods and time-history measurements under the effect of sandy and very silty sand soils. The numerical model of SLIDE 2018 was limited by its inability to incorporate all physical processes governing an overtopping breach failure. Numerical analyses were performed to simulate the development of pore pressures and water content at six positions in the dike's upstream and downstream slopes in physical experimental tests using the van Genuchten Equation and the limit equilibrium method. The numerical results revealed that fine particles increase the pore water pressure and reduce the FOS. Appropriate dike design and maintenance are dependent on surrounding hydraulic conditions, dimensions, and soil types. Non-cohesive materials with fine particles were preferable.

This study aims to determine the material composition and dimensions of X-block, develop a slope reinforcement model using X-block, evaluate the mechanical behavior of slopes that are reinforced with rock-bound by X-block, and analyze the performance of slope reinforcement using X-block. This research was conducted at Hasanuddin University's soil mechanics and civil engineering structure laboratory. The model scale test was employed in this study. The geometrical speciation of the test box is 150 cm in length, 60 cm in width, and 100 cm in height. The X-block model was produced using concrete with a FC of 25 MPa. The X-block was divided into two types: X-block type 1 and X-block type 2. Tensile strength testing is performed on the X-block. The slopes are made of clay soil and have a slope angle of 70 degrees. The loading test was conducted in three stages: without block, with X-block type 1, and with X-block type 2. The loading test uses a hydraulic pump equipped with a load cell and LVDT. The tensile strength of X-block type 1 is 2.56 MPa, whereas X-block type 2 has a tensile strength of 4.35 MPa. The development of the type X-block design, which is used as a retaining wall material, has shown that it can effectively withstand landslides on the slopes under consideration. The slope safety factor rose dramatically after being reinforced with type X-blocks, reaching 2.73 for both X-block type 1 and X-block type 2.

Slope failures and debris flow landslides are among the most significant natural hazards affecting the Nilgiris district in Tamil Nadu, India. The present study focuses on the comprehensive investigation of a slope section in Kurumbadi village within this district, which has been subjected to rainwater infiltration. This research integrates field studies, laboratory experiments, and numerical modeling to assess the stability of the slope under extreme rainfall conditions. Specifically, a 13-day rainfall event from 3 rd to 15 th November 1993 is recorded as the highest total rainfall in the study area and serves as the basis for the stability analysis. The numerical modelling is performed using the Fast Lagrangian Analysis of Continua (FLAC) software, employing a coupled two-dimensional (2D) seepage analysis to simulate rainwater infiltration into the slope. The stability of the slope is further evaluated using the infinite slope method, which considers two distinct soil states: loose and medium-dense. The results of the analysis reveal that soil with medium density exhibits greater resistance to collapse compared to loose soil under identical rainfall intensity and duration. These findings underscore the critical influence of soil density on slope stability during prolonged rainfall events. The outcomes of this study provide valuable insights into the mechanisms of slope failure in the Nilgiris and highlight the importance of considering soil density in the assessment and mitigation of landslide risks in regions prone to heavy rainfall.

This study presents the findings obtained in post-cyclic behaviour and degradation of shear strength from the static triaxial test, cyclic triaxial test and post-cyclic monotonic triaxial test to study the dynamic loading relationships with the degradation of shear strength after cyclic loading to the maximum strain effect due for Hemic peat soil and aim of this research was to assess the post-cyclic loading condition that brought to the understanding of secant modulus by using dynamic triaxial apparatus. It begins with a visual inspection of fibre characteristics. This is followed by an analysis of static, cyclic, and post-cyclic loading with stress-strain behaviour. Shear strength decreased and notched lower strength than its initial strength. As a matter of fact, PNpt-25 kPa from 1, 2, and 3 Hz are accumulated in the adjacent maximum strain. With regards to this maximum strain, the undrained shear strength ratio shows sequent decreases from higher to lower frequency applied. For instance, PNpt-25 kPa-1Hz to PNpt-25 kPa-3Hz recorded 1.16 to 1.13 undrained shear strength ratios, respectively. The secant modulus (Esec) for all specimens reflects decrement. The secant modulus for BSpt at an effective stress of 100 kPa in static monotonic is about 18.74 MPa, while in post-cyclic, the secant modulus expanded to 19.630 MPa cyclically loaded with 1 Hz. Unfortunately, the secant modulus returned to decline position when higher frequency applied at 2 Hz, where the secant modulus is about 12.781 MPa and continues to decline with 3 Hz at 7.492 MPa.

A series of tests and also numerical analyses were conducted to explore the mechanical behavior of a mixture of coarse gravelsize particles floating in a matrix of silt, sand or clay. The research is a step forward in an ongoing investigation on behavior of composite clay, which is used as the core material of some large embankment dams all over the world. After providing the reader with an overall image about behavior of such materials through the literature, the paper focuses on a predominant feature of the composite soil behavior: increase of non-deformable solid inclusions in a mixture leads to formation of heterogeneity of stress field, excess pore water pressure and strain distribution along the specimens. This paper mainly probes formation of such heterogeneity by the aid of special experiments and also numerical analyses. In addition to loading details, it is clarified through the paper that position of inclusions relative to loading direction also affects heterogeneity of stress/strain and excess pore water pressure distribution through the mixture. Despite the former, the latter redistributes with a rate proportional to material hydraulic conductivity.

Wave induced pore pressure and instantaneous liquefaction are known to occur and cause loss of bearing capacity of sand. Wave bottom pressure p forms the boundary condition for the wave induced pore pressure. It is believed that not only variation of the pressure itself, but also the variations of its first and second order spatial derivative play an important role in the formation of liquefaction. An experimental and a preliminary numerical study on unidirectional water wave propagation over a bar are presented. Emphasis is placed upon investigation on the wave induced pressure gradient at the seabed. Single sinusoidal, two-component sinusoidal and five-component sinusoidal waves are investigated in a wave flume of constant water density p. Only the results for single sinusoidal waves are reported herein. The variation of the dimensionless pressure gradient C p = (dp I' 3c) I'{pg) was within ±0.4 for all experiments with a tendency of larger values for downslope gradients (negative values) than for upslope. (g is the acceleration gravity). The numerical results, based on the two-dimensional Green-Naghdi theory for fluid sheets -level II, compare well for sea bed pressures and gradients, but the sea surface does not fit the observations so well.

The impact of rainfall on landslides is not an uncommon issue worldwide, including in Malaysia. It is a major challenge for geotechnical engineers to ensure the constructed slope is safe and can sustain longer periods of time, including during heavy rainfall. Kota Belud, Sabah, has been selected as the study area to meet the study objectives. Heavy rainfall has been recorded every year within Kota Belud, which has caused a repetition of landslide occurrences within the hilly areas, especially during the monsoon season. Presently, there is no local procedure for determining the rainfall intensity value for slope stability analysis. This study utilized the rainfall intensity value from Hydrology Procedure 26. Seepage analysis conducted shows rainwater infiltration has caused the groundwater level to increase from rainfall starts until 0.5 m below ground level and decrease after rainfall stops, creating fluctuations in the groundwater level during the wet and dry conditions within the wetting front. The factor of safety of the slope shows a decreasing trend, with a reduction of around 27 to 33% after 24 hours of rainfall in conjunction with the changes in groundwater level. However, the factor of safety increased by around 3% from the initial condition after 48 hours. The objective of this study is to identify the factor of safety of a rainfall-induced slope within Kota Belud utilizing the rainfall intensity design limits from Hydrology Procedure 26.

One of the limitations of velocity models obtained from seismic method is lack of lateral resolution at low frequencies, since in this method the stacking velocity is used. The major objective of this paper is to cover lateral resolution using refraction tomography. In refraction tomography modeling a correct initial velocity model based on refraction wave data is the main step for tomography inversion. The presented paper focuses on preparation of the initial velocity model for refraction tomography. This model is then used in seismic tomography process to minimize the time difference between the initial model and all first breaks. 31 km 2Dwide-line seismic data of Sefid-Zakhor gas field are selected so that contain exploration well of the field to compare tomography inversion interval velocity model in well location with checkshot interval velocity for validation. The high fit between checkshot and tomography velocity is observed. High accuracy result is derived because of picking first time arrivals both in shotgathers and satationgathers and considers any lateral change as a velocity layer in preparing initial velocity model. However, in the Sefid-Zakhor gas field the data acquisition is discontinues because of its erratic terrain topography, the desired result obtained in the first iteration of refraction tomography inversion because of the accuracy of the initial velocity model. Finally, the drift between well and tomography velocity is applied to the area using MATLAB Software Packages.

Besides direct surface water input of dissolved and particulate compounds (eg nutrients, metals) via rivers into coastal seas, submarine ground water discharge (SGD) is increasingly recognized to be an important factor. In spite of the recognition that many land-sea interfaces of the world are characterised by SGD, it is still unclear how important SGD via springs, seeps, or diffusive outflows

Past studies revealed that excess pore pressure generation due to cyclic loading is highly governed by induced strains, volumetric deformation potential of soil, number of cycles, and bulk stiffness of pore fluid. It is well established that partial saturation can significantly reduce bulk stiffness of pore fluid and consequently excess pore pressure generation during seismic loading. On the basis of that, a number of researchers have investigated induced partial saturation as an effective soil improvement technique to increase the liquefaction resistance of fully saturated soils. This paper focuses on development of a semiempirical model to interpret the effects of partial saturation on the excess pore pressure generation in sands. In this regard, an existing strain based excess pore pressure ratio (r u ) prediction model originally developed for fully saturated soils was modified to incorporate the effect of partial saturation on the excess pore pressure generation. The literature data as well as data from a series of strain-controlled direct simple shear test were used to evaluate the reliability of the proposed equation in predicting the excess pore pressure ratio in partial saturation condition.

Recent studies hypothesize that some submarine slides fail via pressure‐driven slow‐slip deformation. To test this hypothesis, this study derives pore pressures in failed and adjacent unfailed deep marine sediments by integrating rock physics models, physical property measurements on recovered sediment core, and wireline logs. Two drill sites (U1394 and U1399) drilled through interpreted slide debris; a third (U1395) drilled into normal marine sediment. Near‐hydrostatic fluid pressure exists in sediments at site U1395. In contrast, results at both sites U1394 and U1399 indicate elevated pore fluid pressures in some sediment. We suggest that high pore pressure at the base of a submarine slide deposit at site U1394 results from slide shearing. High pore pressure exists throughout much of site U1399, and Mohr circle analysis suggests that only slight changes in the stress regime will trigger motion. Consolidation tests and permeability measurements indicate moderately low (~10−16–10−17...

who while sharing the pleasures and burdens of life have continually affirmed the pursuit of science and given me the support and courage to go on with mine. have continually inspired me over the course of my studies. It has been a tremendous pleasure to be a part of his research group, where I have benefited from the assistance and friendship of Deborah Jahnke and Mary Richards. I thank Drs. Ellery Ingall, Philip Froelich, Markus Huettel, Jay Brandes and Martial Taillefert for serving on my thesis committee and providing helpful comments. I thank Dr. Carolyn Ruppel, for valuable training in numerical modeling techniques and insightful advice along the way. Dr. Ruppel gave me the opportunity to participate in a NOAA expedition to the Blake Ridge aboard the R/V Atlantis and a dive on DSV Alvin at the Cape Fear slide. I am particularly indebted to Dr.

On September 28, 2018, a 7.5-magnitude earthquake struck Palu City, Sigi Regency, and Donggala Regency in Central Sulawesi. It triggered liquefaction in different locations, including Balaroa, Petobo, Jono Oge, and Sibalaya; Typically, a significant number of studies conducted in the Balaroa region relied on a small amount of field test data to cover a rather large area. This research aims to map the liquefaction vulnerability by analyzing the data from both the Swedish Weight Sounding (SWS) and the Standard Penetration Test (SPT) in the Balaroa area. The SWS data was acquired through mapping using a systematic grid sampling method at ten different locations. The liquefaction potential was analyzed based on the N values by converting the SWS data (Nsw and Wsw) to N values using the Inada equation (1960). Afterward, the analysis findings were verified by comparing them with the SPT data obtained from the same area. Based on the SWS and SPT data analysis results, all locations, including the adjacent areas, exhibited very high liquefaction vulnerability. In contrast, the SPT data indicated that the areas further from the spots exhibited low and very low liquefaction. The findings indicated that the occurrence of post-earthquake liquefaction in Balaroa and other regions within Palu City is prone to recurrence following earthquakes of specific magnitudes.

Recently, landslides often occurs in natural slope in Indonesia, which is associated with the coming rainy season . The increment of ground water level cause by rainfall is affected the properties and behavior of soil especially the unsaturated soil. Generally, the stability of slope is evaluated based on safety factor, but the deformation occured at the soil can also be a good interest in assesing the stability of slope. This research is focused to observe the change of pore water pressure and ascoociate deformation considering the hydro-mechanical properties of unsaturated soil due to the effect of varies rainfall. In this research, numerical simulation was carried out to analysis the deformation of the slope affected by pore water pressure change due to rainfall using software-based Finite Element Method of SIGMA/W and SEEP/W from GEO-SLOPE 2004. Unsaturated soil properties, such as Soil Water Characteristic Curve (SWCC) and Hydraulic Conductivity function are obtained from labor...

The Lower Tagus Valley has experienced significant (M 6-7) historical seismicity, evidencing the presence of seismogenic faults. These are still deficiently known due to the low strain rates and the recent alluvial sedimentation of the Tagus River that buries most of the structures, though Paleoseismic evidence was allegedly found by a research team in the Tagus valley, at a site 60 km N of Lisbon, near Vila Chã de Ourique (VCO). According to this team, trenching at the VCO site exposed an active thrust fault, evidencing the surface rupture of a large earthquake that occurred in 1531. Our studies performed at this site, comprising field observations with a reappraisal of the trench outcrops previously excavated, borehole drilling, soil mechanics laboratory testing and seismic reflection acquisition, pointed to the alternative interpretation that the outcropping structures are gravitational and not of tectonic origin. The interpretation of new outcrops crosscutting the structures exposed at the trenches, as well as newly acquired high resolution seismic reflection data, definitely exclude the active thrust fault explanation and support a gravitational slip model for all the observed structures. Gravitational slip in the river bank slope was promoted by low shear strength clays and high pore water pressure coupled with slope toe river erosion. Gravitational slides must have occurred prior to development of the present sedimentation level of the Tagus alluvial plain, which was attained in the last few thousand years as indicated by borehole data and estimations of sedimentation rates.

Interactive web-based visualization tools using Java and VRML (Virtual Reality Modelling Language) are developed to teach/learn fundamental concepts involved in simulation of earthquakes and large scale experimental seismic response of physical models. Experimental earthquake databases usually include numbers of records of time-histories of different measured quantities such as accelerations, displacements, pore water pressures, earth pressures, strain gauges and other quantities. Through animations, interaction and manipulation of images, the visualization tools enable the user to understand relations between measured quantities in space- and time-domains that are difficult to understand by using other means, especially in a large scale experiment environment where hundred of sensors are deployed. A 3-D rendering allows the user to visualize the real experimental model and experimental setup. Concepts such as seismic wave amplification, liquefaction occurrence and extent, and effec...

The evolution of water quality in confined aquifers in the New Jersey Coastal Plain may be affected by leakage of pore water from the adjacent confining units. We investigated the distribution and sources of solutes, particularly Sr, in pore water mechanically extracted from clay-silt core samples collected from depths of 552-840 ft (168-256 m) in the lower Miocene Kirkwood Formation at Atlantic City, New Jersey (Ocean Drilling Program Leg 150X). The sampled sediments consist of thin clay-silt stringers in the upper part of the Atlantic City 800-ft sand, a major aquifer, and the massive clay-silt units above and below it. The distribution of Sr and the ratio of 87 Sr to 86 Sr in the pore water and adjacent shell material were used to identify the possible sources of, and physical processes that may affect the distribution of, Sr in the pore water. Concentrations of Sr in 14 pore-water samples from the clay-silt unit above the aquifer and the clay-silt interbeds in the upper part of the aquifer ranged from 2.74 to 28.19 µM/L; those in the four pore-water samples from the clay-silt unit below the aquifer ranged from 0.52 to 7.30 µM/L. Concentrations of Sr in the samples varied with depth but correlated strongly with pore-water concentrations of Ca, Mg, Na, and SO 4 . Cation-exchange processes may be responsible, in part, for the lower concentrations of Sr, Ca, and Mg in pore water from the clay-silt unit below the aquifer than in that above the aquifer. 87 Sr/ 86 Sr values in 11 samples of aragonitic mollusk shells (bearing no visible evidence of recrystallization) collected from depths in the clay-silt unit similar to those from which the pore-water samples were collected ranged from 0.708468 to 0.708713 , and decreased (Sr in the shells was less radiogenic) with depth. This trend is consistent with the decrease in the 87 Sr/ 86 Sr value in seawater through time during the early Miocene. The 87 Sr/ 86 Sr values in 12 pore-water samples from the studied stratigraphic interval ranged from 0.708257 to 0.708527 and also decreased with depth. The Sr-isotope ratios in the pore water were lower than those in the shell material from nearby or adjacent sediments for all samples but one. Because the only known source of Sr with an isotope ratio this low is shell material from sediments deeper than the strata from which the pore-water samples were collected (including pre-Miocene stratigraphic units), the isotope ratio in the pore-water samples from the lower Miocene claysilt units may result from upward movement of pore water into lower Miocene strata through geologic time, which could create the observed difference in Sr isotope ratios between the pore water and shells.

Both intra-pore hydrate morphology and inter-pore hydrate distribution influence the physical properties of hydrate-bearing sediments, yet there has been no pore-scale observations of hydrate habit under pressure in preserved pressure core samples so far. We present for the first time a pore-scale micro-CT study of natural hydrate-bearing cores that were acquired from Green Canyon Block 955 in UT-GOM2-1 Expedition and preserved within hydrate pressure–temperature stability conditions throughout sub-sampling and imaging processes. Measured hydrate saturation in the sub-samples, taken from units expected to have in-situ saturation of 80% or more, ranges from 3 ± 1% to 56 ± 11% as interpreted from micro-CT images. Pore-scale observations of gas hydrate in the sub-samples suggest that hydrate in silty sediments at the Gulf of Mexico is pore-invasive rather than particle displacive, and hydrate particles in these natural water-saturated samples are pore-filling with no evidence of grain-...

Pertamina Balongan Indramayu's New Construction Jetty & Temporary Access Road Construction Project is the construction of a new jetty (silting prevention pier) located on a loamed land, which consists of dredging work on the area to be built by the jetty, protection of existing pipes, and erection of piles. In the implementation of the jetty construction, there are several reviews that need to be considered, such as soil elastic subsidence and soil consolidation subsidence. The method used for land subsidence is the Preloading method and is combined with the use of PVD to increase the time of decline. The results of this study found an elastic decrease using the Preloading method, a result of 0.7765 meters was obtained due to the presence of a stockpile load and an implementation load of 22.1312 kN/m2 on Elv. ± 1.00 m – STA. 0 + 025 m. Meanwhile, the decrease in consolidation (Sc + Ss) using the Preloading method, obtained a result of 4,949 meters due to the heap load and implem...

The failure of natural dam may occur with a variety of failure modes which includes overtopping, seepage or piping, sudden sliding etc. Natural dams may fail due to seepage or piping because they have not undergone systematic compaction and they may have high porosities. In-depth knowledge of the mechanism of the dam failures by seepage or piping and measured data are still lacking. Extensive laboratory experiments are carried out to study enlargement of the pipe due to internal erosion and resulting outflow hydrographs by varying size of initial pipe, lake water level, lake water volume, slope and location of the pipe. This paper highlights limitations of simplified models used to predict outflow hydrograph due to piping failure of the dam based on experimental results and provides data set for the validation of numerical model. Experimental results show that the initial size, slope and location of pipes have significant effects on magnitude and occurrence time of peak discharge.

Process of failure of landslide dam can be classified into three types; overtopping, instantaneous slip failure and progressive failure. For similar hydraulic conditions peak discharge produced by failure of landslide dam depends on failure modes. Potential disaster in the downstream largely depends on magnitude of peak discharge so this study attempted to derive graphical relationships to predict failure mode by laboratory experiments in the flume. Critical channel slope for sediments, Mix 1-6 and Mix 1-7 are derived from flume experiments. Morevere, experimental data shows peak discharge produced by progressive failure is higher compare with peak discharge produced by instantaneous slip failure and overtopping. The concept of physically based integrated model is essential which can detect failure mode based on initial and boundary conditions and predict outflow hydrograph based on predicted failure mode for downstream hazard management.

Methane gas hydrates are crystalline compounds formed from water and methane under certain pressure and temperature. They are mostly found in marine continental margin sediments and beneath the permafrost and considered as the future non-conventional energy resource. In order to develop innovative techniques for the safe extraction of methane gas from Methane Hydrate (MH) it is important to understand the shear behaviour of methane hydrate bearing sand. It has been reported that the pore scale habits of MH have a significant influence on the shear behaviour of methane hydrate bearing sand. In this paper, an attempt has been made to capture the effect of pore scale habits on the shear behaviour of methane hydrate bearing sand using the Discrete Element Method. Two modelling approaches (i) pore filling, leading to load bearing, and (ii) cementation, bonding of the interparticle contact, have been simulated using PFC3D. A series of triaxial monotonic tests were carried on an assembly o...

The Asmari reservoir in southwest Iran has been producing oil continuously for over 50 years. However, due to an essential pressure decline, the reservoir is now a potential candidate for injection projects. The geomechanical analysis is essential for a successful injection operation to enhance reservoir production and address possible challenges. An accurate estimation of the injection pressure is necessary to maintain optimal conditions during the injection process and reduce possible risks. In this work, a coupled reservoir-geomechanical model, as well as rock mechanical tests, is performed to evaluate not only pressure variation and the associated in situ stress changes but also their potential influences on fault reactivation, reservoir–caprock stability, and surface displacement. For geomechanical evaluation, empirical correlations are derived between static and dynamic rock properties based on core data and existing petrophysical logs for the studied reservoir–caprock system....

In 1971 there is an approach is proposed for the interpretation of magnetic anomalies caused by dipping dikes. developed an automatic depth estimation routine for application to magnetic profile data based on splitting anomalies into symmetric and antisymmetric components and the subsequent matching of the symmetrical component to the magnetic anomalies of standard simple geometrical forms such as dyke, contact and thin plate models. Refinements to the method have been made by Shi ( , 1994) ) who uses horizontal and vertical components of the magnetic field and added an extension for vertical gradient data. In this method of determining depths from magnetic profile data, Naudy Automatic Model calculates the strike of each inferred geological structure using an inbuilt automatic depthdependent trend estimation process. Since estimate the geological strike of anomalies, there are various of depth estimation methods to create 3D geological model, however this technique is based on 2D profile modelling. This study infers how minerals explorer can use the Naudy Automatic Model tool to a set of dyke-like geological structures from a magnetic survey. We used this automatic depth estimation tool provided in the Intrepid software package. Calculated the Naudy Automatic Model from the total magnetic intensity (TMI) to response the best estimates for bodies at intermediate depth. This is the primary automatic modelling tool for dyke swarm analysis, as indicated in a TMI dataset. The workflow relies on a cumulative set of processes to rapidly build a 3D dyke swarm geometry. The purpose of paper has provided a sample survey near Broken Hill, New South Wales, Australia, for use in the case study to demonstrate the methods.

Pile setup or freeze is a phenomenon where the bearing capacity of a pile increases over time both during and after the dissipation of pore pressure and the stabilization of lateral earth pressure. Driven piles gain capacity after installation because of the dissipation of excess pore pressure and soil aging. Incorporating accurate setup prediction into the design of the piles can significantly reduce the cost of many projects by reducing the size or number of required piles. Various simple, empirical mathematical models have been developed to predict pile setup. However, these models are often unreliable, resulting in very conservative designs. Currently, an effective deterministic pile setup prediction model accounting for pore pressure dissipation and soil aging is not available. This study establishes a mechanistically-determined prediction model for pile setup in clay due to aging. It incorporates the remolded friction angle increase with time along the pile wall after the dissipation of excess pore water pressure induced during installation and the Over-Consolidation Ratio (OCR) of the soil. Two coefficients used in the model are determined that appear to be directly related to the properties of the soil. An experimental process is developed using conventional shear strength testing equipment to verify the relationships presented in the model. This new experimental process can be utilized to simulate shear strength increase behavior between a pile and soil over time. The results from the testing program indicate an increase in the residual iii iv shear strength between clay and concrete as time passes. The results also show a greater increase in frictional behavior when the soil has been subjected to a larger stress history prior to shearing. Combining the developed prediction model and the laboratory procedure, a method to predict the frictional resistance of a pile incorporating the pile setup mechanism of soil aging is presented. The calculated time-dependent pile capacity can be applied in the commonly utilized P-method to design the pile dimensions. The author grants to the Prescott Memorial Library of Louisiana Tech University the right to reproduce, by appropriate methods, upon request, any or all portions of this Thesis. It is understood that "proper request" consists of the agreement, on the part of the requesting party, that said reproduction is for his personal use and that subsequent reproduction will not occur without written approval of the author of this Thesis. Further, any portions of the Thesis used in books, papers, and other works must be appropriately referenced to this Thesis.