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Liang Z.-M.,Hohai University | Guo Y.,Hohai University | Hu Y.-M.,Hohai University | Tang C.-Y.,East China Investigation and Design Institute
Shuikexue Jinzhan/Advances in Water Science | Year: 2012

The operation of the Three Gorges Reservoir (TGR) could potentially affect the flow regime in the Poyang Lake and its adopted flood control plan. In this paper, the theory of copula function is used to establish the joint probability distribution functions for hydrological variables in the "Yangtze River-Poyang Lake-five rivers" system without considering the TGR operation. These conditional probability distribution functions are then derived. It is assumed that the conditional distribution function remains unchanged in the system after the TGR operation. The new probability distribution functions for hydrological variables can be obtained after the TGR operation through analyzing the probability distribution function of discharges of the Yangtze River after the TGR operation and combining the new discharge probability distribution function with the previously established conditional probability distribution. The difference in the probability distribution functions before and after the TGR operation can be seen as the TGR impact on the flood control in the Poyang Lake. Results show that the pre-releases from the TGR in May and June will increase the water level of the Poyang Lake. The increase in average water level will be greater than that of the maximum water level, and the low water increase will be greater than that of the high water. Under the influence of the TGR operation, the water level is unlikely to exceed the currently adopted design value. Thus, the flood protection standard of the embankments for the Poyang Lake will remain unchanged after the TGR operation. Source

Ding Y.,East China Investigation and Design Institute | Zheng Z.,Large Dam Safety Supervision Center
Advances in Science and Technology of Water Resources | Year: 2013

In order to ensure the safety and reliability of CFRD's plinth placed on the bank slope of completely weathered bedrock, this paper analyses four key technical issues, including the bearing capacity of foundation, the seepage control of foundation, the stability of plinth, and the differential settlement of plinth. With the engineering example of Vietnamese Tuyen Quang CFRD, some appropriate engineering measures were proposed, which include improving the bearing capacity of foundation, strengthening the connection between plinth and completely weathered bedrock, ensuring the seepage stability of foundation and setting plinth expansion joints in different bedrock junctions. The dam safety monitoring results show that the seepage volume of Tuyen Quang CFRD is small, and the deformation regularity of the dam is normal. By application of the engineering measures proposed in this paper, placing the plinth on completely weathered bedrock is safe and feasible. Source

Di S.-J.,Hohai University | Xu W.-Y.,Hohai University | Wang W.,Hohai University | Wu G.-Y.,East China Investigation and Design Institute
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

The value of joint stiffness based on in-situ deformation experimental results of columnar jointed rock mass in Baihetan dam region was discussed. The value of columnar joint stiffness is obtained by using experimental data of flexible central hole deformation test. The regulation and deformation properties of rock single concept model are analyzed. Rock deformation is made up of two parts, one of rock and one of rock joint, and its hysteretic properties are determined by joints' mechanical behavior. Moreover, the formula of deformation deduced can calculate the equivalent elastic modulus of multi-set intersection joint rock and describe the anisotropic characteristics of jointed rock. A random model of columnar jointed rock mass is established. The rock mass is stimulated by using discrete element method and the stiffness of reverse calculation; and equivalent deformation parameters obtained are in the range of test results. Source

Qian M.,East China Investigation and Design Institute
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014

In recent years, with the development of computer technology and numerical theory of geotechnical engineering, numerical simulation analysis is more and more applied in geotechnical engineering. Based on a deep foundation pit in Qingdao, the geotechnical finite element soft PLAXIS is used to simulate the whole process of double-row piles. The change trend of horizontal displacement is analyzed and compared with the measured data. At the same time the single-row pile supporting method is compared and analyzed, the double-row piles are proved to have obvious advantages in restricting the horizontal displacement. Therefore, the numerical simulation may provide effective help for selection of supporting methods and stability analysis of foundation pits. Source

Ji F.,Chengdu University of Technology | Lu J.,Chengdu University of Technology | Shi Y.,Chengdu University of Technology | Zhou C.,East China Investigation and Design Institute
Natural Hazards | Year: 2013

There are two kinds of excavation methods in underground engineering: the tunnel boring machine (TBM) and the drill-blasting method. A large number of studies have shown that the deformation and failure, the degree of disturbance, the stability and the reinforcement measures of surrounding rock using the TBM and drill-blasting method vary from each other. To accurately master these macroscopic damages, it is necessary to focus on the investigation of the micro-mechanical responses of the surrounding rock. Scanning electron microscopy tests, acoustic emission tests and tunnel acoustic detection tests were carried out to analyze the mechanical response of surrounding rock of tunnels, which were excavated in marble by, respectively, the TBM and the drill-blasting method. The tests results showed that most of the rock fractures cut by TBM is wipe along the crystal, and the failure mechanism is mainly cutting, while most of the rock fractures induced by the TBM coincide with crystal planes, its mechanism is mainly tensile. The stress-strain curves of rocks cut by the TBM method are rather flat around the peak strength, which means a strong resistance to deformation around the peak load. The response of AE for the rock cut by the TBM method appears after larger strains than the response of the rock constructed by the drill-blasting method. This suggests that the resistance to damage is higher under TBM excavation conditions. The relaxation depths of the tunnel excavated by the drill-blasting method are larger than the tunnel excavated by the TBM method. The research can provide more insight into tunnel failure mechanisms and provide a framework for reinforcement measures. © 2012 The Author(s). Source

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