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Zhang C.-R.,Tongji University | Zhang C.-R.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Huang M.-S.,Tongji University | Huang M.-S.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2012

The excavation-induced lateral soil movement may adversely affect any nearby pile foundation systems. A two-stage method is used to determine the additional bending moments and deflections on pile foundations. Firstly, the free field soil movement is used as the input to acquire the lateral differential governing equation of a single pile based on the Winkler subgrade model and deformation compatibility condition. Then, the shielding effect due to pile-soil-pile interaction is considered by the simplified Mindlin's equation. The pile group governing equations are obtained at last and are solved by the finite difference method. Comparisons are made between the observed behaviors of centrifugal model tests and those computed by the proposed method.


Yin Z.-Y.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Huang H.-W.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Hicher P.-Y.,CNRS Research Institute in Civil Engineering and Mechanics
Soils and Foundations | Year: 2016

Experimental observations have shown that the mechanical behavior of sand-silt mixtures is highly dependent on the proportions of sand and silt. Our present paper proposes a simple elastoplastic model for the stress-strain behavior of sand-silt mixtures. The inter-grain contact index is firstly reviewed. A formulation which links the inter-grain contact index with the void ratio is then proposed and validated by measuring the index void ratios of various sand-silt mixtures. The formulation is applied to determine the position of the critical state line of sand-silt mixtures from sand to silt. Based on this formulation, a simple elastoplastic model is then developed. The model parameters can be easily determined from conventional triaxial tests and measurements of the index void ratios. The predictive capability of the model was examined by comparing the simulations and the experimental results of undrained triaxial tests on Foundry and Ottawa sand-silt mixtures from sand to silt. © 2016 Japanese Geotechnical Society.


Chen Z.,Tongji University | Chen Z.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Fan H.,Tongji University | Bian G.,Tongji University
Advanced Steel Construction | Year: 2015

To explore the hysteretic behaviors of shear panel dampers under axial compression, numerical analyses were carried out using the general-purpose finite element software ABAQUS. Two important parameters, namely the axial compression ratio and the web slenderness parameter, were selected as governing parameters. To trace the material nonlinearity, a modified two-surface model was adopted to simulate the constitutive relations of the steel material under cyclic shear loading. Discussions focused on the hysteretic behavior, maximum shear strength, and energy dissipation performance concerning the axial compression ratio. It was found that axial compression deteriorates the hysteretic behavior and energy dissipation performance of shear panel dampers. In addition, under high axial compression, a small web slenderness parameter leads to unexpected brittle failure. © 2015, Hong Kong Institute of Steel Construction. All Rights Reservseed.


Wang M.,Tongji University | Wang M.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Li J.-P.,Tongji University | Li J.-P.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Based on the limit equilibrium concept, the trajectory axis of an arc-shaped arch is simplified to be linear considering the trajectory of the minor principal stress induced by arching effect. A new method for the active earth pressure is proposed through the improved horizontal elements, in which the differential flat elements are divided along the secant direction of the arc-shaped arch trajectory axis of the minor principal stress. Considering a translational rigid retaining wall and cohesionless soil, the theoretical formulas are obtained for the active earth pressure, the resultant earth pressure and the points of applying the resultant earth pressure. In addition, the internal frictional angle of soil, wall-soil frictional angle and angles of sliding plane and horizontal direction, which affect the unit earth pressure, the resultant force of earth pressure and the application point of the resultant force, are investigated. Finally, the proposed formulas produce satisfactory results through comparisons with the experimental observations and other theories.


Zhang Q.,Tongji University | Shen M.,Tongji University | Shen M.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Zhi W.,Changchun University
Journal of Materials in Civil Engineering | Year: 2011

This study reported an investigation on mechanical behavior of off-white marbles that were selected from a slope and underground cavern. The marble samples with weak structural planes were tested through the multistage loading shear rheological method. The results were used to evaluate the creep behavior of the weak structural planes. It was demonstrated from the obtained creep properties and creep rate characteristics of such structural planes under different normal stress conditions that the green schist weak structural planes showed obvious characteristics of brittle failure, and the shear-creep test curve of the structural plane exhibited three obvious stages. Established on the improved Burger model, a further discussion on the shear-creep mechanism was presented. © 2011 American Society of Civil Engineers.


Chen Z.Y.,Tongji University | Chen Z.Y.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Shen H.,Tongji University
Tunnelling and Underground Space Technology | Year: 2014

Isolation layer is one of the countermeasures to enhance seismic safety of tunnels. Its behavior under earthquake is affected by many factors such as shape of the tunnel, stiffness of the isolation layer and the characteristics of the input motion. However, current knowledge on the effects of these parameters on the seismic behavior of isolation layer is limited to lack of experimental data. This paper focuses on the mechanism of isolation layer, especially the efficacy of input motion frequencies on the seismic behavior of a square tunnel with isolation layer around its outer surface. Dynamic centrifuge tests were carried out on model tunnels which took isolation layer as seismic countermeasure using input motion of sinusoidal waves of different frequencies. Actual records of ground motions, magnified to approximate 15. g peak acceleration, formed the basis of the excitations to verify the actual efficacy. Due to the difference between model material (aluminum alloy) and prototype material (concrete), the similar flexural deformation law and the similar axial deformation law could not be satisfied simultaneously. Given the fact that cross-sectional moments were one of the main factors that influenced the safety of tunnels under dynamic loadings, the similar flexural deformation law was accepted in model preparation. The results show that the bending strains of tunnel with isolation layer around its outer surface are lower than those of tunnel without isolation layer, which indicates that isolation layer has positive effect on moment reduction, especially at corners. Increasing of the input motion frequency decreases the dynamic cross-sectional bending moments. In addition, isolation layer has little influence on frequency contents of acceleration response of tunnel. This study has clarified the mechanism of isolation layer on shock absorption, which is proved to be an effective method to improve the safety of tunnel against earthquake. © 2014 Elsevier Ltd.


Gao M.,Shandong University of Science and Technology | Gao M.,Shandong Province Key Laboratory of Civil Engineering and Disaster Prevention and Mitigation | Gao G.-Y.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Gao G.-Y.,Tongji University | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Considering the effects of coupling mass, the transient dynamic response of a cylindrical lining structure subjected to sudden internal uniform loading is studied. Based on the Biot's dynamic theory, the lining structure and saturated soils are respectively treated as the fluid-solid coupling medium and the homogeneous elastic one. A solution to the dynamic response of the lining structure in saturated soils is obtained by means of the Laplace transform and the method of the separation of variables. By utilizing the inner boundary condition of the lining structure and the continuity conditions between the soil and the lining, the unknown coefficients in the expressions are determined. By use of the numerical integration of inverse Laplace transforms, the numerical solution to the problem is presented. On this basis, the dynamic responses of the lining structure in saturated soils are analyzed for different parameters of the soil and the lining. The effects of the coupling mass on the dynamic response of the lining structure are also discussed.


Jiang M.-J.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Jiang M.-J.,Tongji University | Li L.-Q.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Li L.-Q.,Tongji University
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Tongji-1 lunar soil simulant (TJ-1 for short), which is originated from red volcanic ashes from Jingyu County, Jilin Province, was recently invented by drying, crushing, sieving and adjusting the gradation. Physical and mechanical properties of TJ-1 lunar soil simulant (e. g., mineralogy composition, shape of particles, density, specific gravity, internal friction angle, cohesion, compression index, dynamic shear modulus, damping ratio and moisture absorption properties) are measured. TJ-1 demonstrates certain similarity to lunar regolith in terms of physical and mechanical properties, and it is an ideal substitute of lunar regolith located from 0 to 30 cm below the lunar surface in the mare region on the moon. Compared with other simulants introduced in the literatures, TJ-1 has an internal friction angle as high as 45° and hence is advantageous over other simulants when high shear strength is desired.


Huang M.-S.,Tongji University | Huang M.-S.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Wang X.-J.,Tongji University | Wang X.-J.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | And 2 more authors.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

Based on numerical analysis and previous study results, a unified analysis model is established to estimate the ultimate bearing capacity of uplift piles with enlarged base. Under the limit state, it is supposed to form an elliptic local failure mode on the enlarged base, while in the straight shaft, a power function of slip surface is assumed. The failure curve is related to the soil properties and the pile sizes. A concept of H1 is presented, which is the height influenced by the enlarged base. It is an important part in the present method. Then, a formula applicable to the soft soil region such as Shanghai area is proposed to estimate H1. The calculated results are in good accordance with the field ones, proving that the present method is feasible. Moreover, it is also practical in calculating the ultimate bearing capacity of straight-shaft uplift piles.


Huang M.-S.,Tongji University | Huang M.-S.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education | Yu S.-B.,Tongji University | Yu S.-B.,Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2011

A novel method for constructing kinematically admissible velocity fields in the upper bound limit analysis is introduced. It is based on rotational block set, which is formed by a number of triangular wedges, and the construction of admissible velocity fields can be simplified to a combination of several rotational block sets. An application to the upper bound analysis of deep strip anchor in undrained clay is given to illustrate the utility and effectiveness of the proposed method, and include detailed comparisons with the results obtained by means of other approaches. It is shown that the value of pull-out capacity factor (11.42) for deep strip anchor is independent of the incline angle of anchor.

Loading Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education collaborators
Loading Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education collaborators