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Chen L.,Soochow University of China | Chen L.,Institute of Geotechnical Engineering | Du Y.-J.,Nanjing Southeast University | Liu S.-Y.,Nanjing Southeast University | Jin F.,University of Cambridge
Journal of Hazardous, Toxic, and Radioactive Waste | Year: 2011

In this study, electrical resistivity was related to the fundamental geotechnical properties of cement solidified/stabilized heavy metal-contaminated soils. Lead-contaminated soils were artificially prepared with various concentrations and treated by portland cement Type I at three content levels. The compacted cylindrical specimen was prepared with a diameter of 50 mm and height of 100 mm. The apparent electrical resistivity, electrical conductivity of pore fluid, unconfined compressive strength, and water contents were measured at different curing times. The result shows that the apparent electrical resistivity increases with the increase of curing time and the decrease of porosity and saturation degree as a result of cement hydration development. The effects of lead concentration, cement content, and curing time on the apparent electrical resistivity were discussed. The cementation index m was used to evaluate the cementation degree of cement-treated lead-contaminated soils. Lead pollutant at high concentrations could suppress or retard the hydration of solidified/stabilized soils. Electrical resistivity measurements can be used as a nondestructive method to evaluate the hydration development of solidified/stabilized lead-contaminated soils. © 2011 American Society of Civil Engineers.

Xue F.C.,Tsinghua University | Xue F.C.,Institute of Geotechnical Engineering | Zhang J.M.,Tsinghua University | Zhang J.M.,Institute of Geotechnical Engineering
Recent Advances in Environmental Vibration - Proceedings of 6th International Symposium on Environmental Vibration, ISEV 2013 | Year: 2013

High-speed railway has gained rapid development in China. Running speeds on the established lines are no less than 200 km/h at the beginning stage and up to 300 km/h for many main high-speed railways. The running speed is likely to be increased in the future. Compared to low and middle speed railways, dynamic effects induced by high-speed train are obviously different, especially in regions with poor quality soils. To investigate the vibration effect of foundation due to highspeed moving loads, a subroutine complied with Fortran language? is added on the platform of the computer software ABAQUS to simulate one or more different types of moving load(s). To eliminate wave reflection at computational boundary and to remove the limitation of traditional viscoelastie boundary that is valid for dynamic; calculation but invalid for static calculation, a special boundary is added to ABAQUS based on the theory of three dimensional static-dynamic unified viscoelastie artificial boundary and its correctness and validity are verified. Considering nonlinearity of material, the vibration effects of foundation are studied for the two cases; ( i) when the speed of a moving load is larger than the shear wave velocity but less than the compression wave velocity; and (ii) when the speed of a moving load is larger than the compression wave velocity of foundation soil. And, vibration displacement, vibration velocity, vibration acceleration and dynamic stresses are obtained. Results indicate that the stress state of soil elements keep (-hanging all the time during the process of load moving and three stress axes correspondingly rotate continuously. For comparison, rotations of axis in vertical plant due to one load with moving speed less than the shear wave velocity of foundation soil art presented.

Rosen J.B.,Geosyntec Consultants | Arnold M.A.,Institute of Geotechnical Engineering | Bachus R.C.,Geosyntec Consultants | Schauer D.,Geosyntec Consultants | Berrios A.,Bauer Foundation Corporation
Geotechnical Special Publication | Year: 2011

Large scale geotechnical earthworks projects, specifically those related to earth dams, dikes, and levees, often require construction of deep vertical seepage barriers. The demands on these projects of contract compliance, resource scheduling, quality control, and budget management require structured and efficient management of the large associated data sets. Ineffective data management can contribute to the complexity, duration and budget of the project. This paper discusses an application of Geographic Information Systems (GIS) technology to capture information from multiple data streams and provide geotechnical feedback, quality control, and project control feedback. This technology was used to provide information to the U.S. Army Corps of Engineers (USACE) as part of the high-profile rehabilitation of the 232-kilometer long Herbert Hoover Dike (HHD) around Lake Okeechobee in South Florida. The implication of this technology to other earthwork projects is demonstrated. © 2011 ASCE.

Hu H.,Institute of Geotechnical Engineering | Zhu H.-X.,Beijing MTR Construction Administration Corporation | Jia L.-H.,Institute of Geotechnical Engineering
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

By use of numerical methods for the excavation of foundation pits and piles in row by the subway, the separation action of secondary stress at different embedded depths is analyzed, and the rebound of subway foundation by the excavation foundation pit is studied. Based on the software of FLAC3.30, the stress releasing is simulated, the displacement and stress vectorgraphs of subway foundation owing to the pit excavation are analyzed when the model depth of subway is larger or smaller than the excavation dept. The results indicate that the rebound of subway foundation is small when the depth is larger than the pit depth and it is large when the depth is smaller than the pit depth, and satisfactory parameters of piles can be obtained at different depths of the subway foundation.

Cui C.-Y.,Dalian University of Technology | Cui C.-Y.,Dalian Maritime University | Luan M.-T.,Institute of Geotechnical Engineering | Li M.-G.,Dalian University of Technology
Geotechnical Special Publication | Year: 2010

On the soft grounds, effects of consolidation on performance of the system of piled rafts as well as superstructures cannot be overlooked due to nonlinear interaction characteristics. Conventional methods of engineering design and numerical procedures of two-dimensional interaction analysis cannot realistically simulate loading and deformation mechanism of the interaction system and cannot completely predict variations of deformations and internal forces of both structure and piled raft foundation. Therefore in order to well understand long-term behavior of the interaction system, time-dependent effect of soil deformations on performance of the interaction system of piled rafts and foundations as well as superstructure is evaluated in this paper. The nonlinear deformation and strength behavior of foundation soils are taken into account by using the elasto-plastic constitutive model based on Mohr-Coulomb's yield criterion while the consolidation effect of subsoil under loading is incorporated by numerically solving the coupling Biot's equations of consolidation. Numerical analyses are conducted for the structure-raft- foundation interaction system by using the finite element methods. Based on numerical analyses for a given interaction system, both the features of variation in time of internal forces, settlements and the characteristics of compatibility mechanism of interaction system are examined. It is shown that both nonlinear behavior of soft soils and consolidation characteristics of foundation remarkably affect the time-dependent performance of the interaction system. Such dependency is intimately related to variation of excess pore water pressure of subsoil. © 2010 ASCE.

Chen C.-F.,Hunan University | Xiao S.-J.,Hunan University | Xiao S.-J.,Institute of Geotechnical Engineering
Yantu Lixue/Rock and Soil Mechanics | Year: 2010

The design tensile and prestressing force calculation method of anti-slides pile with prestressed cables are summarized and improved, which makes the methods consider displacement coordination of pestressed cable and pile. According to each case of prestressed cable acting on pile top and pile body, the semi-analytic and semi-numerical weighted residual method is applied to stress calculation of anti-slides pile with prestressed cables; and the extensively adapted B-spline function is used as trial function; then the calculation program is worked out; and the program can consider soil resistance above sliding surface in front of pile. The program is applied to analyze existing example; and its result is compared with the result obtained by finite difference method; the reliability of the method is proved. Simultaneously, the proposed method is applied to another two calculation examples; aiming at different calculation methods of anchor design tensible and prestressing force, the comparative analysis table with relevant design tensible force, prestressing force, maximum bending moment of pile body and pile top displacement is presented respectively; pile force diagram is given; and the calculation also shows that it is not every method suitable for specific calculation example; and it must take concrete analysis of concrete issue.

Chen R.-P.,Institute of Geotechnical Engineering | Chen R.-P.,Zhejiang University | Li J.,Institute of Geotechnical Engineering | Li J.,Zhejiang University | And 4 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

The shield technology has been widely used in underground construction. The face stability is the key problem in the shield tunneling. Large-scale model tests on the face stability of tunnels with the ratios of tunnel depth to diameter C/D=0.5, 1.0 and 2.0 are conducted in the dry sand. The influence of C/D on the ultimate support pressure and the settlement of ground surface are obtained. The support pressure decreases sharply with the increase of the face displacement. However, the settlement of the ground surface is not sensitive to the support pressure before the residual support pressure. Both the support pressure and the ground settlement are essential to the monitoring of the face stability in the shield tunnelling.

Tensay B.G.,Institute of Geotechnical Engineering | Wu W.,Institute of Geotechnical Engineering
Numerical Methods in Geotechnical Engineering - Proceedings of the 7th European Conference on Numerical Methods in Geotechnical Engineering | Year: 2010

The seismic performance of earth dams is usually studied by two dimensional space. However, considerable effort is required to estimate the overall three dimensional dynamic response of dams in a narrow canyon from plane strain analyses of the dam. This is so because the plane strain analysis normally ignores the arching effect of the valley. Researches reported in this paper represent 3D numerical study of an earthfill dam founded on a liquefiable foundation subjected to earthquake loading and effect of canyon geometry on its seismic performance. The shape of the canyon is varied to determine the related effects to the earth dam. A finite difference numerical scheme is used for the study. The assumed 3D model contains all details of the dam body and foundation materials of Tendaho earthfill dam in Ethiopia. Results and discussions related with the significance of these two factors for the seismic performance evaluation of earth dams are presented. © 2010 Taylor & Francis Group, London.

Berhe T.G.,Institute of Geotechnical Engineering | Wang X.-T.,Institute of Geotechnical Engineering | Wu W.,Institute of Geotechnical Engineering
Geotechnical Special Publication | Year: 2010

During earthquakes, the materials of earthfill dams undergo significant changes in their properties. These modified properties of the soil affect the stability of the dam. The most severe situation is dam failure due to liquefaction of the granular soils in the shoulders. The development of liquefaction is directly related to the excess porewater pressure that would develop during earthquake shaking. The generation and dissipation of excess porewater pressure is a phenomenon that depends on the drainage possibility and length of drainage path. Therefore, with some modifications on the slope of the dam, the clay core can assume different arrangements. These arrangements modify the seismic response of the dam. Numerical codes are useful tools to investigate the safety of dams in seismic prone areas. In this paper FLAC3D numerical tool is used. The influence of the arrangement of the clay cores of the dam on the development of porewater pressure and crest settlement of earthen dams, and hence seismic performance of earthen dams is investigated. Based on the numerical investigations, the performance of earthfill dams increases with increase in the angle of inclination of the center line of the core from the vertical towards the upstream. So the arrangements of the clay core for dams in seismic areas can be taken as one design criteria during earthfill dam design. © 2010 ASCE.

Li Y.,Institute of Geotechnical Engineering | Li Y.,Sinosteel Maanshan Institute of Mining Research | Yang Y.-S.,Institute of Geotechnical Engineering | Yang Y.-S.,Sinosteel Maanshan Institute of Mining Research | And 3 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2013

The plane strain analysis method was widely adopted in evaluation of dump slope stability. It is embarrassed that, dumps sometimes destroyed but the safety factor was go over the allowable value. Regardless of those issues had been mentioned frequently, such as mechanical parameters, constitutive model and so on, the spatial clamp effect of convex and divergent effect of concave and slide-body-end effect are also play vital roles in analysis of slope stability. For those reasons, proceed from conditions of plane elevation data, geological section, drilling data and others, Kriging interpolation method, which can obtained a smooth effect of interpolation, was adopted, and then the three-dimensional (3D) geological model of dump was built. Then an interface program, wrote by FISH, was used to import the 3D-model into FLAC3D to discretization and calculation. In this way, the issues mentioned above can be figure out efficiently. Trinity function include 3D geological modeling, model visualization, geotechnical analysis was achieved in a simple and highly efficient way. An example of Jianshan seventh dump of Lanjian Iron Mine, Pangang Group co. Ltd. of China, was concerned by previous mean, 3D stress-strain analysis was carried out, 3D global safety factor was also calculated by 3D strength reduction method. It turned out that the results was accordant to the field investigation and plane strain analysis conclusion. Results calculated by the 3D geological model cannot be affected by dump spatial effect and slide-body-end effect, the general stress-strain pattern, which obtained from the method, can be instructive and meaningful to production management for open-mine dumps.

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