Geotechnical Engineering

The inhabitants of a village situated in the southern side of Romania have sued juridical action the local mining company considering that the coal quarry and the new sterile dump situated near up the locality. arc the main cause of the civil buildings damages. In order to establish the true causes of damages occurred in the village area a number of 129 buildings has been monitoriscd and 19 gcotechnical drillings were dug surveying the ground structure. Inclinometric tests have been performed for one year in 15 boreholes spread on several profiles. A global stability analysis was performed as well. Our study pointed out that, despite the appearances. the damages are due to local previous landslides and inadequate foundation solutions.

This paper discusses a range of geotechnical testing capabilities available at the University of California, San Diego (UCSD). The capabilities discussed are part of overall large-scale UCSD laboratories, one of the largest and most active earthquake engineering laboratories worldwide. Specifically, testing using 2 different shake tables is discussed, one being the largest outdoor shake table in the world. Illustration of the capabilities are shown for soilstructure-interaction (SSI) tests of embedded structures as well as pile foundations in dry and saturated soil scenarios. The testing models were densely instrumented with top of the line sensor arrays. Instrumentation includes strain gauges, pressure and excess pore-pressure sensors, accelerometers and displacement pots. The method of construction is presented, and the stages clearly described.

System identification techniques are employed to characterize the stiffness and damping characteristics of a dense sand stratum at low dynamic excitation conditions. The identification process utilizes a large database of input-output accelerations recorded in a highly instrumented centrifuge experimental program conducted by researchers at the University of California at Davis. This paper presents a computational effort based on the recorded small shaking events, where the peak ground surface acceleration ranges from 0.05g to 0.196g in amplitude. The dynamic behavior of the prototype stiff soil site near its first resonance is modeled by that of a one-dimensional shear beam. An employed system identification process attempts to define the shear wave velocity profile and damping that provide a best match to the experimental dynamic soil response near the first resonance, along a central downhole accelerometer array. Both linear viscous and hysteretic soil models are utilized in this identification study. The identified properties are found to be consistent among the investigated events, and are in good agreement with other laboratory estimates. The calibrated (via system identification) shear beam predications were found to be an excellent match to those recorded at all central downhole accelerometer locations around the first resonance.

Since the observation of ground motions in South Korea, liquefaction manifestation was the first to be observed in Pohang earthquake in 2017 with M L 5.4. Because liquefaction causes ground settlement and lateral spread damaging in-ground or super structures, various researchers have been analyzing the Pohang liquefaction case history to better understand and predict liquefaction consequence and to prevent future disasters. In prior research at the 2018 EESK * 본 논문에 대한 토의를 원하는 회원은 2019년 2월 28일까지 그 내용을 학회로 보내주시기 바랍니다. 저자의 검토 내용과 함께 논문집에 게재하여 드립니다.

The moisture degree of capillary rise is an indicator of the state of conservation of earthen construction and their mechanical response to load cases, especially seismic action, since the buildings diminish resistant capacity where they are more demanding by the base shear. This paper shows a test procedure and a specific device to evaluate the rate of rise and variation of moisture content in samples of soil for use in new or existing walls of adobe and tapia. These parameters allow evaluating the suitability of building material, the improvements efficiency to increase its quality (modification of its texture, compactness, and composition), choice and dosage of additives for moisture control. In addition, in case of patrimonial buildings affected by rising damp, allows to design and to prove procedures for structural rehabilitation, and using them in the building after evaluating his efficiency and scope.

In recent years, substantial changes have occurred in the morphology of the River Tigris within Baghdad City. Although huge volumes of sediment are being trapped in recently constructed headwater reservoirs, the number of islands in the Tigris at Baghdad is increasing. The debris of bridges destroyed in the wars of 1991 and 2003 and their subsequent reconstruction have enhanced the development of these islands. As a consequence the ability of the river to carry the peaks of flood waters has been reduced. This has led to potential increase of flooding in parts of the city. The bed of the River Tigris has been surveyed on three occasions (1976, 1991, and 2008). The most recent survey was conducted by the Ministry of Water Resources, extended 49 km from the Al-Muthana Bridge north Baghdad to the confluence with the Diyala River south Baghdad. It yielded cross-section profiles at 250 m intervals. The data are used to predict the maximum flood capacity for the river using the one-dimensional hydraulic model for steady flow "HEC-RAS" modeling. Calibration of the model was carried out using field measurements for water levels along the last 15 km of the reach and the last 10 yr of observation at the Sarai Baghdad gauging station. The model showed a significant predicted reduction in the current river capacity below that which the river had carried during the floods of 1971 and 1988. The three surveys conducted on the same reach of the Tigris indicated that the ability of the river to transport water has decreased.

Recent studies on arsenic (As) contamination in surface water and groundwater in the Manipur valley have been conducted to examine spatial distribution and role of geomorphology and geology. It was observed that As concentration in lakes and rivers are within the WHO and BIS limit, but springs and shallow groundwater exceed the recommended limits (76 mg/L). Newer alluvial plain is more prone to high As concentrations as compared to the springs located around piedmont zone and older alluvial plain owing to the presence of Holocene sediment deposits. The main source of As could be derived from geogenic and mobilized due to weathering and erosion of rocks and minerals like arsenopyrite and ferrous arsenic sulphite from Disang shale, Barail sandstone and Manipur Ophiolite rocks. Further, detail studies in terms of identification of the source of elevated As in groundwater needs to carried out in this region.

This report documents the research efforts conducted at the Louisiana Transportation Research Center (LTRC) regarding chemical stabilization of the naturally wet and problematic clayey soils typically found as subgrade in south Louisiana and provides detailed information on experiment design, instrumentation, and field and laboratory tests. The objectives of the study included the exploration and development of a methodology to build reliable and conservatively achievable subgrade layers, stabilized with cementitious agents at various field moisture contents so that a treated subgrade layer would not only provide a working table for pavement construction, but could also function as a pavement subbase layer that contributes to the overall pavement structural capacity. Three additives were studied throughout this research: cement, lime, and lime-fly ash. Testing included moisture density evaluations, various additive percentages, various molding moistures and curing times, tube suction testing, resilient modulus and permanent deformation, Eades and Grim tests, and Accelerated Loading Facility (ALF) tests on similar full-scale pavement sections with cement-stabilized and lime-treated subgrades with the magnitude of the ALF loads kept at 9,750 lb. for the first 200,000 repetitions then increased in incremental intervals of 2,300 lb. The laboratory and field research confirmed that among subbase treatments evaluated, cement stabilized soil provided the best performance followed by lime-treated soil. Field and laboratory results also indicated that treating clays with lime and silts with cement will create stronger foundations for pavement structure, because when the appropriate additive and amount is added, the treatment modifies the soil to create consistent, drier layers with improved strength and stiffness and reduced moisture sensitivity as compared to the raw natural soil. A life cycle cost analysis based on the field test results of this study revealed that using a 12-in. cement stabilized soil subbase in lieu of a lime-treated working table layer will create a 37 percent annualized cost savings for low-volume and 31 percent cost savings for highvolume pavement structures in Louisiana. The primary recommendation emphasized the expanded use of treated subgrade layers with target strengths applied to all subgrades susceptible to moisture intrusion in Louisiana -rather than optional, working table, subgrade treatment. Treatment alternatives should be based on a benefit cost analysis. Additionally, updates to the Standard Specifications are paramount, which foster implementation and increased options of chemical additives to treat wet subgrade soils at competitive costs, while still producing effective subbase and treated subgrade layers.

LTRC is conducting a research project to determine the seasonal variation of subgrade resilient modulus (MR) in an effort to implement PavementME. One objective of that project, which is presented in this paper, was to locally calibrate the Enhanced Integrated Climate Model’s (EICM Fenv) curve for seasonal subgrade MR changes. Shelby tube sampling was conducted on six different roadways to a depth of approximately 7.92 m beneath the shoulder pavement’s base course. The AASHTO T-99 MR test method was used on all samples with an additional eight specimens being tested with NCHRP 1–28A MR test method. Four soils from Louisiana which were not from the six roadways were also tested and included in the analyses. Once the MR tests were completed and plotted, it was noticed that there was a rather large scatter (R2 = −0.266) around the EICM Fenv curve. The authors hypothesized that this occurred due to the density differences between in situ and remolded specimens. Further analyses confirme...

This report documents the research efforts conducted at the Louisiana Transportation Research Center (LTRC) regarding chemical stabilization of the naturally wet and problematic clayey soils typically found as subgrade in south Louisiana and provides detailed information on experiment design, instrumentation, and field and laboratory tests. The objectives of the study included the exploration and development of a methodology to build reliable and conservatively achievable subgrade layers, stabilized with cementitious agents at various field moisture contents so that a treated subgrade layer would not only provide a working table for pavement construction, but could also function as a pavement subbase layer that contributes to the overall pavement structural capacity. Three additives were studied throughout this research: cement, lime, and lime-fly ash. Testing included moisture density evaluations, various additive percentages, various molding moistures and curing times, tube suction testing, resilient modulus and permanent deformation, Eades and Grim tests, and Accelerated Loading Facility (ALF) tests on similar full-scale pavement sections with cement-stabilized and lime-treated subgrades with the magnitude of the ALF loads kept at 9,750 lb. for the first 200,000 repetitions then increased in incremental intervals of 2,300 lb. The laboratory and field research confirmed that among subbase treatments evaluated, cement stabilized soil provided the best performance followed by lime-treated soil. Field and laboratory results also indicated that treating clays with lime and silts with cement will create stronger foundations for pavement structure, because when the appropriate additive and amount is added, the treatment modifies the soil to create consistent, drier layers with improved strength and stiffness and reduced moisture sensitivity as compared to the raw natural soil. A life cycle cost analysis based on the field test results of this study revealed that using a 12-in. cement stabilized soil subbase in lieu of a lime-treated working table layer will create a 37 percent annualized cost savings for low-volume and 31 percent cost savings for highvolume pavement structures in Louisiana. The primary recommendation emphasized the expanded use of treated subgrade layers with target strengths applied to all subgrades susceptible to moisture intrusion in Louisiana -rather than optional, working table, subgrade treatment. Treatment alternatives should be based on a benefit cost analysis. Additionally, updates to the Standard Specifications are paramount, which foster implementation and increased options of chemical additives to treat wet subgrade soils at competitive costs, while still producing effective subbase and treated subgrade layers.

Geological disposal of radioactive waste is being planned by many countries. Bentonite clay is often included in facility design, providing a barrier to radionuclide migration. Gas, generated by the waste or corrosion of waste canisters, may disrupt the properties of the bentonite. Robust prediction of this interaction is, therefore, necessary to demonstrate safe facility evolution. In some cases, gas may deform the clay, resulting in localised flow; however, the nature of this deformation has been widely debated. Accurate numerical representation of this behaviour has been limited by a shortage of information on the degree/distribution of deformation. Using experimental data from gas injection tests in bentonite, we show that first order fluctuations in the stress field can provide this information. We show that hundreds of microdeformation events can be detected, with similar characteristics to established fracturing phenomena, including earthquakes and acoustic emissions. We also...

A coupled multiphase fluid flow and discrete fracturing model is applied to simulate bench-scale gas migration experiments on compacted bentonite. The numerical modeling is based on the linking of the multiphase fluid flow simulator TOUGH2 with a Rigid-Body-Spring Network model, which enables a discrete (lattice) representation of elasticity and individual fractures. The evolution of a complex network of dilatant flow paths is modeled through opening and breakage of lattice interface bonds between porous-elastic matrix elements. To achieve a good match with the experimental results, including an abrupt gas breakthrough along with pressure and stress responses, it was necessary to calibrate model parameters for (1) air-entry pressure, (2) shear and tensile failure of lattice interface bonds, (3) moisture swelling/shrinkage effects on stress, and (4) aperture-dependent permeability of dilatant flow paths. Our best-fit conceptual model considers a pervasive network of discrete flow paths propagating from the gas injection point, whereas some of the experimental data indicate the potential for heterogeneous and unstable flow paths.

In seguito al terremoto che ha colpito la regione Abruzzo il 6 Aprile del 2009, nell'ambito del progetto Microzonazione sismica dell'area Aquilana, l'unità di geofisica dell'Istituto per l'Ambiente Marino Costiero del CNR, coordinato dal dott. Vincenzo Di Fiore, veniva incaricato dal Dipartimento di protezione Civile ad effettuare una serie di indagini downhole in 8 Macroaree comprendenti la città di L'Aquilla e frazioni limitrofe. A partire dal mese di agosto del 2009 e fino alla fine del mese di novembre dello stesso anno, l'unità di geofisica ha acquisito ed elaborato i dati di campagna restituendo i risultati ottenuti ai coordinatori delle diverse macroaree. L'attività del gruppo ha previsto anche il supporto tecnicoscientifico nelle diverse riunioni che si sono svolte durante la fase di redazione della microzonazione sismica.

Recently, landslides often occurs in natural slope in Indonesia, which is associated with the coming rainy season. The increment of ground water level caused by rainfall has 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 occure at the soil can also be a good interest in asses the stability of slope. This research is focused to observe the change of pore water pressure and associate 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 analyze 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 laboratory test and also predicted based on grain-size distribution using psycho-empirical method in SOILVISION Database. HAVARA is used to help rainfall data analysis using statistic approach. Rainfall model is used to vary the moisture content to model unsaturated soil condition. There are six rainfall models, consists of one steady state model and followed by five transient model to accommodate the pore water pressure changes due to rainfall. The results show that rainfall with intensity near saturated permeability of soil gives more significant influence in increasing pore water pressure and deformation than normal rainfall even with long duration. Proposed countermeasure by providing counterweight and sub drain do not significantly take effect the deformation, but it could improves the safety factor significantly, so that the slope is more in stable condition.

Understanding the mechanical behavior of ballast aggregates under multi-axial loading is key in railway foundation analysis and design. UBCSAND is an effective-stress constitutive model which can predict static and dynamic behavior of granular materials under combined shear and normal stresses. This study presents results from a suite of triaxial monotonic and cyclic compression tests for four different aggregates (gabbro, limestone, demolished concrete, steel slag) and discusses the applicability of UBCSAND model for simulating the relevant non-linear stress-strain curves. To this end, UBCSAND is integrated, for the first time, analytically for shear and volumetric strains, to facilitate calibration against experimental data. Four novel solutions are derived, expressed in terms of monomials and Gauss' hypergeometric functions (2F1) of the stress ratio (q/p'). Variation in the calibrated parameters is discussed considering different loading conditions and types of aggregates.

Unreinforced high bond strength thin layer mortared masonry shear wall is an emerging structural system and hence there is a need to probe its structural responses for better understanding and safer usage in practice. For a detailed understanding of structural response, it is required to probe all possible failure modes of high bond strength masonry shear walls for various aspect ratios (H/L), pre-compression pressure ( pc iii

This study presents an analysis of the association between the coefficient of permeability of active clays and their porosity and tortuosity. Montmorillonite was selected because it is used as a barrier in geo-environmental projects and its sensitive structure results in wide variations in permeability when in contact with pore fluids. The microstructural approach was selected for a numerical simulation using the discrete element method (DEM). A DEM code was developed by considering the mechanical force, diffuse double-layer repulsion, and van der Waals attraction as the inter-particle interaction. The coefficient of permeability was calculated by simulating consolidation tests, and the DEM simulations were compared with the experimental data. The results show that the coefficient of permeability decreased as the void ratio decreased. At the same void ratio, there was a deviation between the coefficient of permeability for clay-electrolyte systems caused by the micro-fabric and variations in tortuosity. Micro-fabric evolution during loading showed that increasing the stress state caused a reorientation of the particles perpendicular to the direction of loading and increased the anisotropy of the particle orientation, increasing the tortuous flow path. A dispersed or oriented structure can occur at the same void ratio for different clay-electrolyte systems, causing variations in the coefficient of permeability.

The Sea to Sky Highway will be upgraded in preparation for the Vancouver 2010 Olympic and Paralympic Games. An 800 m long test section was constructed to demonstrate that the proposed upgrades to the Sea to Sky Highway were achievable across very difficult terrain while at the same time minimizing impacts to the traveling public. Mechanically Stabilized Earth (MSE) retaining walls are required along substantial lengths of the highway alignment to support the southbound lanes of the proposed highway widening. This paper describes the design approach adopted for the MSE walls on rock fill slopes along the Sea to Sky Highway Test Section that includes both reliability and deformation (FLAC) analysis. Some construction considerations are also described.

River captures are drainage rearrangements commonly reported in divides of high topographic gradient, triggered by headward erosion. Captures also occur in divides of low topographic gradient through differential fluvial incision between rivers, however, in a smaller proportion of reports, mainly in dry regions. Thus, this research contributes to the theme by investigating possible river captures in the semi-arid equatorial margin of South America related to the Jaguaribe River, which flows over intermountain depressions. This study used morphological and sedimentary evidence obtained in field expeditions and by application of morphometrics (local relief, paleotopographic modelling and χ variable). Among the results, the following stand out: depressions drained by radial tributaries upstream of water gaps; opposing headwaters with relative extension that drain low-relief divides, damming fluvial-lacustrine sediments and transfers signatures of upstream areas. These data suggest drainage rearrangements and a possible endorheic phase during the study area evolution. Continuous incision of the Jaguaribe River conditioned river captures by rupture of paleodivides supported by structural ridges (shear zones). In this context, the drainage rearrangements were effective for the configuration of the Jaguaribe River, even in a region of low topographic gradient and water flow instability.

Masonry infills are commonly used in buildings for functional and architectural reasons. The structural contribution of infill walls cannot simply be neglected particularly in regions of moderate and high seismicity where the frame-infill interaction may cause substantial increase in both stiffness and strength of the frame in spite of the presence of openings. In the present study an attempt is made to study the initial lateral stiffness of the infilled frames with central opening of different sizes for varying modulus of masonry (2750 Mpa and 1000 Mpa modulus) using the finite element analysis . The percentage reduction in the initial lateral stiffness of infilled frames due to varying modulus of masonry is obtained. The initial lateral stiffness of infilled frame is also determined by single equivalent diagonal strut analysis by varying the width of strut and a strut-width-reduction factor is proposed to determine the strut width for the opening present in the infill panel.

The geotechnical characterisation with surface waves involves the full-wave recording, the estimation of the experimental dispersion curve and its inversion. In multistation method the dispersion curve is obtained by picking maxima of the f-k spectrum, which is strongly influenced by spatial sampling. As a consequence, an apparent dispersion curve is obtained, resulting from difficulties in separating the energy associated to different modes. The following critical aspects are discussed using numerical and experimental data:-the limit on the maximum k may be critical with wide bandwidth dispersion curves;-the resolution in k affects the precision of the phase velocity determination and the possibility of discriminating different modes;-the k interpolation produced by zero padding increases the accuracy of maxima positioning while the capability of peak separation depends only on the actual array length.-windowing introduces in the k spectrum ripples that can mask the presence of secondary modes. These sampling issues can lead to a quite irregular and misleading behaviour of the experimental dispersion curve if they are not correctly assessed in the design of the testing array. The criteria introduced for spatial sampling issues are also in agreement with the necessity of limiting near field effects.

This paper reports the results of experiments evaluating the corrosion resistance of a mixture of limestone-clay (MLC) and perlite in concrete mixes. Variables were MLC and perlite additions of 0–15% as cement replacement and cement contents. Electrochemical measurements tests were used to monitor the corrosive behaviour of embedded steel bars in concretes. Results showed that additions of MLC and perlite are effective in inhibiting corrosion of reinforcing bars. The superior performance in inhibiting corrosion in reinforcing steel is attributable to the densification of the cement-paste matrix due to pozzolanic action in the additives concrete mixes. INTRODUCTION Mild steel embedded in concrete is protected against corrosion by both a chemical and a physical mechanism. Chemical protection is provided by the high pH of the concrete, which causes passivation of the reinforcing steel. Concrete also provides physical protection, by hindering the access of aggressive agents. Severe corr...

Breakwater is often required for erosion protection. The effectiveness of breakwater structure as a coastal defence could be determined through overtopping wave surpass onto its crest freeboard structure. The common design practice of breakwater structure is using a linear ramp configuration. There is still a limited knowledge on the contribution of various configuration ramps shape into breakwater efficiency. Thus, this study attempts to investigate a few other's configuration of ramp geometries through overtopping discharge rate performance and identified its relationships with the crest freeboard. Three configurations of ramp geometries (convex, concave and cubic) have been investigated using numerical simulation of CFD-Flow 3D software. The result indicates that, there are significant influences of ramp configuration parameters on the overtopping rate and the highest overtopping rate is contributed from cubic shape ramp geometry. It is recommended that the detail study on cu...

practice for over a century, mainly in the cold regions of the world. AGF is considered as a ground improvement technique which can improve the site conditions for various civil engineering projects. It is typically used for ground stabilization and ground water control for wide variety of applications in all soil types. In-depth knowledge of the frozen soil characteristics through experiments and the development of suitable constitutive models that suit the geological conditions of our country are necessary to predict the strength and behaviour of the frozen soils. The strength and mechanical behaviour of this material can be determined experimentally and can be even predicted numerically. As this technology is not yet explored in our country an apparatus to test the strength of frozen soil in the triaxial condition is not yet developed in the laboratory. As part of this study a triaxial compression apparatus is designed and fabricated to test frozen soil samples incorporating the features of the existing triaxial apparatus on the basis of the reviewed literature and hence determining the shear parameters and strength of C-Phi soil. A more precise strength comparison between the frozen and unfrozen soil sample is done effectively in this investigation.

Groundwater is an essential resource for drinking water, but its contamination with potentially toxic elements and arsenic (As) is a global issue. To evaluate As and its levels in the Coachella Valley, the US Geological Survey (USGS) collected 17 groundwater samples. This study looked into the arsenic distribution, enrichment, hydrogeochemical behavior, and health risks associated with the samples. The comparative analysis between groundwater contamination in Greater Palm Springs and similar regions, could provide valuable insights into regional differences and common challenges. The hydrogeochemical facies showed the dominance of calcium and magnesium-bicarbonate-carbonate, indicating permanent hardness and salt deposits of residual carbonate. The Gibbs plot demonstrated that chemical weathering of rock-forming minerals and evaporation are the primary forces impacting groundwater chemistry. Geochemical modeling revealed saturation for calcite and dolomite, and under-saturation for ...

This paper is conducted to determine the sensitivity and thixotropic effects of clay soil for selected sites in Diwaniya city which are: (Dawr Aldubbat, Al-Zawra square, 14 Ramadan square, Al'iiskan Alaqadim and Military square). The main aim of this investigation is to study the sensitivity and thixotropy of clay soil, and determination and classification of soils to (Insensitive), (slightly to very sensitive) and (slightly to extra quick)) relying on special test methods in sensitivity and thixotropic phenomena. The experimental tests that were done including geotechnical, chemical and mineralogical tests to natural soils and special tests were for the identification and classification of sensitivity of soils. The results of sensitivity of soils test displayed low to medium for all the types of the soils in the study area. The results of the thixotropic strength ratio test showed a small increase in thixotropic strength ratio values with time. The results of Atterberg limits t...

The shove test (ASTM Standard C1531) is an experimental technique aimed at studying the shear-sliding behavior of brick masonry. It can be executed according to various testing methods that differ in the way the vertical compression load is applied and in the way bricks and/or joints are locally removed for inserting jacks. One of the most critical aspects is the correct evaluation of the compressive stress state on the sliding brick. The objective of the present paper is to investigate the capability of the shove test in determining the shear strength parameters of brick masonries and to highlight the main advantages and disadvantages of the various testing methods. To this aim, nonlinear numerical simulations of the shove test were performed by adopting a brick-tobrick modeling strategy. The 2D numerical model was calibrated and validated through comparisons with experimental results of triplet tests and shove tests. The numerical analyses allowed to understand the influence the different testing methods and the masonry mechanical properties, such as dilatancy, may have on the test results. Based on the numerical outcomes, correction factors were calibrated for the proper evaluation of the compressive stress state on the sliding brick. Improvements with regards to the experimental procedures, i.e. additional test phases and measurements, were also proposed to enhance the results interpretation.

A landslide can consist of multiple failures advancing upslope retrogressively. This paper investigates the mechanism of a seepage-induced retrogressive landslide in a silty sand slope and assesses the accuracy of the limit equilibrium analysis in predicting the stability and sequential failure surfaces at retrogressive failures. A centrifuge model test was performed on a 12-m-high silty sand slope with an inclination of 45°at 50 g using a 4.5 m radius large beam centrifuge facility available at IIT Bombay. Seepage was generated using an in-flight simulator, and the behavior of the model slope was monitored. Three retrogressive slides were observed in the slope model when the seepage flow was established. The results indicated that the time interval between initial and second failure episodes is more prolonged than between second and last failure episodes. The length of sliding surfaces decreases when the landslide retrogresses, although their depth remains roughly unchanged. In addition, the slope with an inclination of 63.4°(2 V:1H) had significantly higher values in normalized depth, depth of displaced mass, and retrogression distance than those for 45°slope inclination. The limit equilibrium approach can estimate the stability at pre-failure stages, provided that pertinent geometry and loading conditions are satisfactorily incorporated.

Abstract This paper evaluates performance of anchored geosynthetic systems (AGS) on stability of slopes under seepage condition using a centrifuge modeling technique. A series of centrifuge tests were carried out at 50 g on unreinforced and AGS slope models, using a centrifuge container equipped with seepage flow simulator. AGS slope models were tested by varying slope inclination, number of anchors and keeping inclination of anchors as constant. The water was allowed to seep through the model slopes during flight at 50 g. Ground anchors were modeled as drilled pre-tensioned anchors using sand epoxy mixture, polyester strand and a plastic tube. An anchor inclination of 15° with the horizontal was adopted for AGS slopes. A layer of geocomposite was used for modeling geosynthetic component of anchored geosynthetic systems. All models were instrumented to measure surface settlements and pore water pressure within the slope at onset of seepage during centrifuge test. A digital image analysis technique was adopted to trace displacement vectors of plastic markers embedded toward the front elevation of the model and plastic markers glued to facing during model construction. Analysis and interpretation of centrifuge model test results indicate that the stability and deformation behavior of slopes, under seepage conditions, can be substantially improved using anchored geosynthetic systems. With an increase in slope inclination and reduction in number of anchors, surface settlements and face movements were observed to increase substantially. Further, stability analysis results on the unreinforced and AGS slope models were found to be in good agreement with those of physically observed centrifuge test results.

Suction stress is one of the most significant factors affecting the serviceability and stability of soil structures. This study presents a framework for analyzing the stability of geosynthetic reinforced soil (GRS) walls and slopes under unsaturated conditions. An analytical formulation of suction stress-based effective stress was implemented into a limit equilibrium solution, namely, the top-down procedure. The developed framework enables the prediction of the tensile load distribution and connection load between the reinforcement and wall face considering the pullout resistance of reinforcements in GRS walls backfilled with granular and marginal soils under unsaturated conditions. The applicability of the framework was demonstrated by providing an illustrative example followed by three series of parametric studies to understand the effects of pore size distribution, air entry pressure, and infiltration rate on the performance of an unsaturated GRS wall. The results quantify the impact of suction, showing that as it increases, the maximum tensile loads and connection loads decrease while pullout resistance increases. Mostly affected by the suction effect are upper reinforcement layers, where combined effects of reduced tensile load and increased pullout resistance decrease connection load and reinforcement length requirements. The current study strongly discourages counting on the contribution of suction for the design of new GRS walls. The suction value cannot be accurately and reliably determined for the entire lifespan of the GRS wall, and it may decrease or diminish in an uncontrolled and random manner under infiltration. However, by quantifying the effect of suction, the proposed framework in this study provides a valuable tool for analysis purposes, enabling a rigorous interpretation of field-measured reinforcement loads during wall service as well as evaluation of the forensics of failed GRS walls.

Indonesia records exceptionally high rainfall, particularly during the rainy season when almost all areas of the country are consistently showered with heavy rain. Vigilance is therefore crucial due to the risk of flooding from overflowing rivers or dams. It is essential to develop flood monitoring systems to mitigate the risk and impact of flooding. This study aimed to design and build a flood monitoring system with parameters that support flood warnings. These include measurement of the water level using an ultrasonic sensor and rainfall using a tipping bucket-based hall sensor. The flood detection system was installed at Pondok Aren, Tangerang Selatan, Banten. A website was developed to display information on water levels and rainfall measurements every 10 minutes, as well as cumulative rainfall over 24 hours, presented in values, tables, and graphs. The device design included a warning feature in the form of a strobe light that would activate if the water level exceeded the minimum threshold in addition to providing rainfall status notifications. The system performed well in trials, with data transmitted to the database every 10 minutes. Raingauge sensors exhibited a 0.86% error rate, while the ultrasonic sensor showed an average error rate of just 0.25%.

In modeling the hydraulic fracking program for unconventional reservoir shales, information about elasticity rock properties is needed, namely Young's Modulus and Poisson's ratio as the basis for determining the formation depth interval with high brittleness. The elastic rock properties (Young's Modulus and Poisson's ratio) are a geomechanical parameters used to identify rock brittleness using core data (static data) and well log data (dynamic data). A common problem is that the core data is not available as the most reliable data, so well log data is used. The principle of measuring elastic rock properties in the rock mechanics lab is very different from measurements with well logs, where measurements in the lab are in high stresses / strains, low strain rates, and usually drained, while measurements in well logging use the principle of measured downhole by high frequency sonic. vibrations in conditions of very low stresses / strains, High strain rate, and Always un...

The parameter of the shale brittleness index is the key to success in hydrocarbon shale stimulation, as in Barnett Shale, Texas, USA, where brittleness is controlled by quartz content. Based on the mineral content of the shale, the ductility (opposite of brittleness) is controlled by the content of clay and calcite. The Brittleness index determines the value of ductile and brittle a rock formation, based on its mineral content. Brittleness of hydrocarbon shale, needed for initiation and propagation of hydraulic fracturing and fracture re-opening. Shale fractability can be evaluated based on geomechanical and mineralogical evaluations for optimization of stimulation planning. Laboratory tests on shale samples from the Brown Shale Formation, Pematang Group in the Central Sumatra Basin, were carried out to obtain elastic properties of rocks, such as Young's Modulus, Poisson's ratio, and unconfined compressive strength. Furthermore, mineralogical analysis is carried out to predict brittleness based on the results of the XRD test, which produces mineral content in rocks. Brittleness analysis is very important for hydraulic fracturing stimulation planning, and to get a valid calculation result from BETRO-001 well log data which is dynamic data, it must be validated using static data, namely from uniaxial compressive tests on in-situ rock cores, but because of the difficulty of obtaining core data from BETRO-001 well drilling and other wells in the research location, a coring approach from analog outcrops is considered to represent the target formation. From the results of prospect criteria according to Matt McKeon (2013), it can be concluded that the Brown Shale Formation in Bengkalis Trough has good hydrocarbon shale potential and can be carried out for further research, because oil production from conventional Indonesian reservoirs in general has experienced a significant decline.

The soil-structure interaction (SSI) of R. C. building frames including basements below ground level has been the subject of extended research, mostly in the form of theoretical dynamic analysis. There are different issues concerned with this type of work, as e.g. the location of the base of the structure. Usually, the base of the structure in dynamic analysis or according to the codes is the level at which the lateral displacement is zero. According to this definition, and with the presence of basement floors and the soil mass below, the ground level may not be the base of the structure. The soil stiffness around basement walls has a great effect on the lateral displacement of the basement floor. Another issue is the effect of the presence of the basement floors on the dynamic behavior of the structure. A third issue is the effect of the soil around the basement walls and the soil mass below the foundation in general, which is known as the SSI. In this paper, 3-dimensional regular ...

Extreme rainfall is a common triggering factor of landslide disasters, for infiltration and pore water pressure propagation can reduce suction stress and shear strength at the slip surface. The subsurface hydrological model is an essential component in the early-warning system of rainfall-triggered landslides, whereas soil moisture and pore water pressure simulated by the Darcy–Richards equation could be significantly affected by uncertainties in soil hydraulic parameters. This study conducted an inverse analysis of in situ measured soil moisture in an earthquake-induced landslide deposit, and the soil hydraulic parameters were optimized with the Differential Evolution Markov chain Monte Carlo method (DE-MC). The DE-MC approach was initially validated with a synthetic numerical experiment to demonstrate its effectiveness in finding the true soil hydraulic parameters. Besides, the soil water characteristic curve (SWCC) and hydraulic conductivity function (HCF) described with optimize...

Geotextiles and jute fibers both have been successfully used for reinforcement of soils to improve the bearing capacity. In the present study, firstly the geotextile is used as a tensional material for reinforcement of granular soils. Laboratory California Bearing Ratio (CBR) tests were performed to investigate the load-penetration behavior of reinforced and unreinforced granular soils with geotextile. By placing geotextile at certain depth within sample height in one, two or three layers were tested under soaked condition to investigate the effects of the number of geotextile layer on the increase in bearing capacity. Secondly, laboratory tests were performed to investigate the behavior of granular soil reinforced with jute fiber of various aspect ratio mixed with soil at 0.5%, 1.0%, 1.5%, 2.0% by weight of the soil. Finally, the granular soil was reinforced with the combination of geotextile (top and middle layer of the sample) and jute fiber (0.5% and 1% by the weight of soil). The experimental results were then studied and compared to determine the most effective combination of geotextile and jute fiber to reinforce the studied granular soil.

WaLoWa stands for Wave Loads on Walls and is a Hydralab+ project funded by the European Union. Ghent University (Belgium), TU Delft (The Netherlands), RWTH Aachen (Germany), Politechnico Bari and University of Florence (Italy) and Flanders Hydraulics Research (Belgium) are jointly working on the WaLoWa project. The user team leader is Ghent University. The WaLoWa project is hosted by Deltares and the Delta Flume facility. When storm walls and buildings are located on top of a dike or promenade, overtopping waves can induce large forces on these structures as has e.g. been observed at the Belgian coast which has a specifically shallow foreshore. Especially during storm season and in times of sea level rise these loads can be highly destructive. It is therefore the key objective of WaLoWa to study overtopped wave loads on structures situated on top of a dike and in shallow foreshore conditions.

WaLoWa stands for Wave Loads on Walls and is a Hydralab+ project funded by the European Union. Ghent University (Belgium), TU Delft (The Netherlands), RWTH Aachen (Germany), Politechnico Bari and University of Florence (Italy) and Flanders Hydraulics Research (Belgium) are jointly working on the WaLoWa project. The user team leader is Ghent University. The WaLoWa project is hosted by Deltares and the Delta Flume facility. When storm walls and buildings are located on top of a dike or promenade, overtopping waves can induce large forces on these structures as has e.g. been observed at the Belgian coast which has a specifically shallow foreshore. Especially during storm season and in times of sea level rise these loads can be highly destructive. It is therefore the key objective of WaLoWa to study overtopped wave loads on structures situated on top of a dike and in shallow foreshore conditions.