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Li J.-J.,Tongji University | Li J.-J.,Shanghai Jianke Project Management Co. | Huang M.-S.,Tongji University | Wang W.-D.,East China Architectural Design and Research Institute | Chen Z.,East China Electric Power Design Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

Determination of the ultimate bearing capacity of an uplift pile under deep excavation has been paid much attention to by more and more geotechnical engineers. The theoretical analysis of this problem becomes a hot research topic recently. Unfortunately, due to the limitation of in-situ test conditions, it is almost impossible to obtain the ultimate uplift capacity of tension piles under deep excavation from field tests. Accordingly, centrifuge model tests on uplift piles under deep excavation are performed to examine the load transfer characters and the ultimate bearing capacity. The variation of displacement, friction resistance and internal axial force of the uplift piles before and after deep excavation is analyzed. And then the centrifugal model tests results are used to verify the rationality of the FEM and the limit equilibrium method. The calculated results by the two theoretical methods have good agreement with the results of centrifugal model tests. Source

Wu C.-J.,Shanghai JiaoTong University | Chen J.-J.,Shanghai JiaoTong University | Ye G.-L.,Shanghai JiaoTong University | Wang J.-H.,Shanghai JiaoTong University | Zhou H.-B.,Shanghai Jianke Project Management Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The current studies on foundation pits are reviewed. Compared with those in Shanghai, the hydro-geological conditions in Suzhou are analyzed. The excavation faces are located on (5)3 with poor geological conditions. The measured data of a typical foundation pit indicate that the average maximum displacement of the building envelope by use of diaphragm walls or secant piles is about 0.16%H, and the average settlement of ground is 0.13%H. Three-dimensional numerical analysis is employed to simulate the process of the excavation of the representative station, Suzhou Leyuan Subway Station. It is found that the displacement of the toe of diaphragm walls is relatively large. The conclusions from the construction of the Subway Line One of Suzhou will be contributing to the future construction of subway stations in Suzhou. Source

Liu W.-L.,Shanghai Shentong Metro Co. | Ju L.-Y.,Shanghai Shentong Metro Co. | Gao W.-J.,Shanghai Jianke Project Management Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

Taking into account the difficulty of quantitative risk assessment of underground engineering because of the uncertainty, the semi-quantitative risk assessment method is proposed based on engineering application and risk management experience of foundation pit in soft soil. The method contains two steps. Firstly, risk assessment criterion has been built; Secondly, risk levels is obtained to compare the engineering information with the risk assessment criterion. The criterion is formed mainly by endue corresponding risk levels to different categories combinations of properties, after classifying the criteria about general and individual procedures of foundation project. The classifying criteria is based on the detailed analysis of four aspects of risk factors: engineering characteristics, geological and hydrological conditions, surrounding environment and construction technology. Eventually, this method is verified to be simple and worth spreading by engineering practice. Source

Zhang Z.-M.,Zhejiang University | He J.-Y.,Zhejiang University | Zhang Q.-Q.,Zhejiang University | Zeng L.-C.,Shanghai Jianke Project Management Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2010

The data based on the static load tests and settlement observations show that the compression of the piles accounts for a considerable part of the total settlement of the piles under the working loads. Simultaneously, the side resistance of the piles takes a large part while the end resistance of the piles takes a small one. The ultimate pile-soil relative displacement of 17~20 mm is needed for the super-long piles to bring their side resistance into full play at the upper half of the piles in the clay. After that, the soil slides and the friction is degraded. The settlement of pile-group foundation increases as the load becomes larger and larger. The rules are as follows: the main building and the podium settle down simultaneously at low floors (below the 5th floor); then the main building continues its settlement and has a 'settling promotion effect' to the completed podium with taller floors (above the 30th floor); after the 30th floor, the podium shows upwarping because of the 'pulling up effect' due to the large relative settlement of the tube of the main building's, while the total settlement is small, so the differential settlement in the edge points and surrounding points of the main building, podium and tube is not obvious. And the settlement ratio of the pile groups first increases and then decreases with the increase of loads. Source

Xie X.,Tongji University | Yang Y.,Tongji University | Ji M.,Shanghai Jianke Project Management Co.
Tunnelling and Underground Space Technology | Year: 2016

There is an ever-growing demand of construction of large-diameter tunnel in Shanghai, China. How to minimize the environmental impact induced by the tunnel construction has been a hot topic of research over the recent years. The Yingbin San Road tunnel with an external diameter of 13.95m has been taken as an example to elaborate the controlling of ground surface deformation induced by shield-driven tunneling, in the case of tunnel passing through the settlement sensitive area and adverse geological conditions. Tunneling process of the EPB shield machine was simulated using a three-dimensional finite difference method. Parametric study was performed to optimize the construction parameters. Field measurement was also carried out to validate the numerical model and its applicability in the case of large-diameter tunnels. Both the numerical prediction and field test data show that grouting pressure and quality appear to determine the surface settlement rather than the supporting pressure at workface on the premise of guaranteeing the safety of tunneling process. Both the empirical correlations and field observations demonstrate that the volume loss Vi should be controlled below 0.2% to guarantee the maximum surface settlement no more than 10mm in the airport area. However, the empirical predictions of trough width parameter i do not match the field measurement very well except for the case where such a high volume loss as 0.81% was obtained. © 2015 Elsevier Ltd. Source

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