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Cen W.-J.,Hohai University | Wang J.,Hohai University | Wang S.,Guangdong Hydropower Planning and Design Institute | Xiong K.,Chang Jiang Survey Planning Design and Research LLC
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2013

Rapid drawdown of reservoir has a great influence on the seepage, deformation and stability of an earth-rock dam. Under earthquakes, it may pose a new threat to the dam safety. Combined with a 300 m-super high core wall earth-rock dam to be constructed, the unsteady and saturated-unsaturated seepage analysis of the dam under the rapid drawdown of reservoir is carried out and the pore water pressure is acquired. Based on the seepage and static stress field, the seismic response of the dam is analyzed to get the basic dynamic response. Meanwhile, the evaluation of seismic stability and permanent deformation of dam slope are also conducted to evaluate its seismic safety. The results show that rapid drawdown of reservoir mainly affects the distribution of pore water pressure of the core and upstream dam body, causes the large change of static average effective stress field of the upstream region of the dam for the high core wall rockfill dams with good barrier performance core and upstream filter protection. The occasional earthquake will significantly affect the dynamic response and the seismic performance of upstream dam slope, and more attention should be paid to it. The change of water level does not affect the distribution of seepage field of the downstream dam body obviously. Therefore, the rapid drawdown of reservoir has little influence on the seismic safety of downstream dam body. Source

Feng K.,Southwest Jiaotong University | He C.,Southwest Jiaotong University | Zou Y.-L.,Chang Jiang Survey Planning Design and Research LLC
Gongcheng Lixue/Engineering Mechanics | Year: 2012

The effect of assembling method on the inner force of segmental lining for cross-river shield tunnel with large cross-section has been concerned for a long time. Different assembling plan yields different distribution characteristics of inner force. In this paper, theoretical analysis is carried out to discuss the mechanism of assembling effect of circular shield tunnel, especially the effect of longitudinal interaction on circumferential inner force. Then based on Nanjing Yangtze River Shield Tunnel project, a prototype test is conducted to study the mechanical distribution characteristic of circumferential inner force in different assembling plan and the mechanical distribution characteristic of inner force of target segment (B5) along the circumference and width direction. The results show that, the effect of the interaction intensifies bending moment in local area when using staggered assembling, and the growth of bending moment and decline of axial force become larger near the longitudinal bolts. And along the width direction, the positive bending moment distributes as a concave type, the negative bending moment and axial force distribute as a convex type. The result can provide valuable references to design and construction of large-profile underwater shield tunnels; meanwhile it can also provide important reference to the correlative studies. Source

Yuting Z.,Yangtze River Scientific Research Institute | Xiuli D.,Yangtze River Scientific Research Institute | Qitao P.,Yangtze River Scientific Research Institute | Zhiguo Z.,Chang Jiang Survey Planning Design and Research LLC
Open Civil Engineering Journal | Year: 2015

The mechanical response of geological fault structure and its interaction with surrounding rock are crucial for the stability of caverns in hard rocks. Geological fault structure exhibits unique mechanical response subjected to rock excavation. Potential failure patterns and their corresponding criterions of geological faults, including open failure, slip failure and block instability, are summarized. Corresponding numerical models and proper supporting measures are recommended for open and slip failures, respectively. Rock damage model is adopted to better illustrate the interaction of rockmass and geological faults. Safety factor for anti-sliding is introduced to quantify the safety extent of caverns subjected to open and slip failures caused by geological faults. Case study shows that the presented methods are effective to describe the mechanical response of geological faults and also to provide quantitative references for reinforcement design of rock caverns. © Yuting et al. Source

Zhang M.-Y.,Wuhan University of Technology | Song H.-Z.,Wuhan University of Technology | Li B.,Chang Jiang Survey Planning Design and Research LLC | Li Y.,Hubei Engineering University
Yantu Lixue/Rock and Soil Mechanics | Year: 2012

A predictive model of ultimate bearing capacity for large-diameter and super-long steel pipe piles is established based on Support Vector Machine(SVM) and Independent Component Analysis(ICA). Firstly the FastICA algorithm of independent component analysis is imported to abstract the independent components, which can better express the essence in sample data and keep statistics independent without correlation as well as obey the Gaussian distribution, from large-diameter and super-long steel pipe pile data measured in an actual engineering. Secondly, by determining the support vector machine as classifier, whose input are the previously extracted components and whose output is the predicted bearing capacity, ICASVM_Q model is established to predict bearing capacity of large-diameter and super-long steel pipe piles. By data testing of a bridge engineering, it is shown that the predicted results of ICASVM_Q are better than SVM_Q which uses original engineering data as input of SVM model. Studies indicated that the modeling method by combining SVM and ICA used to predict ultimate bearing capacity of large-diameter and super-long steel pipe piles is feasible and the predicting bearing capacity of the ICASVM_Q model can be referred by designers in engineering. This method can also serve as a reference of intelligent forecast in other areas. Source

Sun W.,Wuhan University | He Y.-L.,Wuhan University | Yuan S.,Wuhuan Engineering Corporation | Xiong K.,Chang Jiang Survey Planning Design and Research LLC
Shuili Xuebao/Journal of Hydraulic Engineering | Year: 2014

Based on the collection, sortation, statistics and analysis of Hardfill material mechanics performance indexes, Monte-Carlo stochastic finite element method is adopted to study the static working behavior of Hardfill dam with considering the heterogeneity of material mechanical properties influence and the random field of the modulus of elasticity has been built. The results show that the displacement response is small and the amplitude of changes is not more than 13.7%, while the stress response is relatively greater and the amplitude of changes is not less than 18.8% and maximum reaches 110.5%. The mean responses of stress and deformation of dam are consistent with the homogeneous model. The variability of stress and deformation of the upstream and downstream, the top, the heel, and the toe of the dam is strong and the maximum variation coefficient reaches 0.21, while the internal part of the dam is not very prominent and the coefficient of variation is not more than 0.08. After the superposition with three times standard deviation, the rate of the displacement of the extreme points is not more than 5%, while the rate of the stress of the extreme points is not less than 18.4% and maximum reaches 375%. Source

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