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Ye A.,Tongji University | Lu C.,Shanghai Tunnel Engineering and Rail Transit Design and Research Institute
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2010

Treating a group pile foundation as one entity component, an approach of seismic performance analysis for group pile foundations was developed, based on Pushover analysis. A load model and a nonlinear structure model (inelastic pile model and nonlinear boundary condition) for group pile foundations were established, and two specific seismic performance indices, displacement ductility factor and resistance amplification factor, were proposed. The seismic performance analysis of a real group pile foundation was conducted. Based on the nonlinear structural model of the group pile foundation, a series of load cases were developed, the corresponding Pushover curves, the displacement ductility factors, and the resistance amplification factors were calculated. The results indicated that, the axial force and bending moment at the bottom of the pile cap slightly influenced the seismic performance index, while their effects on the lateral force and displacement in yield and ultimate limit state were significant. The displacement ductility factors and resistance amplification factors were quite small under all types of loadings.


Tan Y.,Tongji University | Li M.,Shanghai Tunnel Engineering and Rail Transit Design and Research Institute
Geotechnical Special Publication | Year: 2011

A 26 m deep metro station was excavated in the soft clays within downtown Shanghai, where exist many commercial and residential buildings. The minimum distance between the excavation and the buildings in the proximity was only 7 m. In order to ensure the safety of the adjacent buildings and associated facilities, building settlements were monitored throughout the construction. Field data indicated that the buildings underwent significant settlements during construction. The magnitudes of building settlements were governed by the distances between buildings and excavation pit, structural types, and foundation types. Based on the analysis of field measurements, some interesting findings about excavation-induced building settlements were obtained. © 2011 ASCE.


Ge S.-P.,Tongji University | Ge S.-P.,Shanghai Shentong Metro Construction Group Co. | Xie D.-W.,Shanghai Tunnel Engineering and Rail Transit Design and Research Institute | Ding W.-Q.,Tongji University | Ouyang W.-B.,Shanghai Urban Construction Design and Research Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

The distribution of the lining stiffness of shield tunnels is uneven for the lining structure composed of several segments and joints, and the weak links are at the segment joints. The correct determination of the segment joint stiffness is crucial for the simulation of construction process of the shield tunnels, the determination of the surface settlement trough and the accurate estimation of ground loss. A simplified method, district modified stiffness method (DMSM), is proposed for simulating segment joints based on the stress and structure of segment joints, which corrects the stiffness at the place of joints and the nearby areas and maintains the stiffness of the rest segment regions. A formula for determing the segment joint stiffness is deduced, and a method for determing the relevant parameters is proposed based on the Saint-Venant principle and the variable stiffness beam theory. The numerical simulation and comparable analysis of deformations of segment joints caused by positive and negative bending moments are performed based on laboratory full-scale tests on segment joints. The results show that the proposed method can simulate the mechanical behaviors of the segment joint well, and is helpful for refined three-dimensional analysis of construction process of the shield tunnels.


Lin Y.-L.,Shanghai University | Zhang M.-X.,Shanghai University | Li X.-X.,Shanghai Tunnel Engineering and Rail Transit Design and Research Institute
Meitan Xuebao/Journal of the China Coal Society | Year: 2011

More than one set of anchors with different orientations can be economical solution to completely stability the rock slope. A new computational model for evaluating asismic stability of multi-directional anchored rock slope was presented after taking the supporting effect of rock-bolts, surcharge, seismic force and fissure water pressure into consideration. In this proposed method, not only the factor of safety but also the permanent sliding displacements could be totally calculated. Sever special cases of this expression were found to similar to those reported in the literature. Parametric analysis show that depth of water in tension crack, blocked outflow suture, surcharge have a disadvantage effect on the rock slope stability, and anchorage effect of anchor blots have a advantageous effect on the rock slope stability.


Lin Y.,Shanghai University | Li X.,Shanghai Tunnel Engineering and Rail Transit Design and Research Institute
Tumu Gongcheng Xuebao/China Civil Engineering Journal | Year: 2014

Based on JRC-JMC failure criterion, a new computational model for evaluating asismic stability of anchored rock slope is presented, incorporating most of the practically occurring destabilizing forces under depth of tension crack, seismic loading conditions, anchorage effect of anchor blots and parameters of the structural plane. The results show that the depth of tension crack has a significant effect on shear strength, and the stability factor of slope remains basically the same. Seismic loading has a disadvantage effect on the rock slope stability against sliding, while the friction angle increases slightly with increase in the seismic loading. It is also shown that the larger the stabilizing force is, the better the slope against sliding will be. With the increase of JRC, JMC and JCS, the safety factor of the slope increases gradually, the greater the JMC is, the more closely to the practical rock.

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