A key problem in gravity dam design is providing enough stability to prevent slide, and the difficulty increases if there are several weak structural planes in the dam foundation. Overload and material weakening were ...A key problem in gravity dam design is providing enough stability to prevent slide, and the difficulty increases if there are several weak structural planes in the dam foundation. Overload and material weakening were taken into account, and a .finite difference strength reserve method with partial safety factors based on the reliability method was developed and used to study the anti-slide stability of a concrete gravity dam on a complicated foundation with multiple slide planes. Possible slide paths were obtained, and the stability of the foundation with possible failure planes was evaluated through analysis of the stress distribution characteristics. The results reveal the mechanism and process of sliding due to weak structural planes and their deformations, and provide a reference for anti-slide stability analysis of gravity dams in complicated geological conditions.展开更多
Based on the deep analysis of the mathematical model of an autonomous underwater vehicle( AUV),comprehensive considerations are given to the coupling effect of AUV's longitudinal velocity on the other degrees of f...Based on the deep analysis of the mathematical model of an autonomous underwater vehicle( AUV),comprehensive considerations are given to the coupling effect of AUV's longitudinal velocity on the other degrees of freedom. In the meantime,discussions are made on the influence of residual buoyancy and restoring moment.A novel S-plane controller established on sliding mode control( SMC) is hereby proposed in this study. The strengths of traditional S-plane controller including simple structure and easily adjustable parameters are maintained in the improved design while the weakness of unsatisfactory control effect at the time of high-speed operation is also overcome. Lyapunov function is introduced to make the stability analysis of the controller before it is successfully applied to the basic motion control of AUV-X. Then the comparative experiment test is carried out between the traditional S-plane controller and the novel S-plane controller. The effectiveness and feasibility of the novel S-plane controller established on sliding mode control in the AUV basic motion control is verified by the comparative analysis of experiment results.展开更多
The stability of a gravity dam against sliding along deep-seated weak planes is a universal and important problem encountered in the construction of dams.There is no recommended method for stability analysis of the da...The stability of a gravity dam against sliding along deep-seated weak planes is a universal and important problem encountered in the construction of dams.There is no recommended method for stability analysis of the dam on deep-seated weak planes under earthquake condition in Chinese design codes.Taking Tingzikou dam as an example,the research in this paper is focused on searching a proper way to evaluate the seismic safety of the dam against sliding along deep-seated weak planes and the probable failure modes of dam on deep-seated weak planes during earthquake.It is concluded that there are two probable failure modes of the dam along the main weak geological planes in the foundation.In the first mode,the concrete tooth under the dam will be cut and then the dam together with part foundation will slide along the muddy layer;in the second mode,the dam together with part foundation will glide along the path consist of the weak rock layer under the tooth and the muddy layer downstream the tooth.While there is no geological structure planes to form the second slip surface,the intersection of the main and the second slip surface is 40 to 80 m downstream from dam toe,and the angle between the second slip surface and the horizontal plane probably be 25 to 45 degrees.展开更多
基金supported by the Innovation Program for College Graduate of Jiangsu Province of 2007 (Grant No. CX07B_133Z)
文摘A key problem in gravity dam design is providing enough stability to prevent slide, and the difficulty increases if there are several weak structural planes in the dam foundation. Overload and material weakening were taken into account, and a .finite difference strength reserve method with partial safety factors based on the reliability method was developed and used to study the anti-slide stability of a concrete gravity dam on a complicated foundation with multiple slide planes. Possible slide paths were obtained, and the stability of the foundation with possible failure planes was evaluated through analysis of the stress distribution characteristics. The results reveal the mechanism and process of sliding due to weak structural planes and their deformations, and provide a reference for anti-slide stability analysis of gravity dams in complicated geological conditions.
基金Sponsored by the National High Technology Research and Development Program of China(Grant Nos.2011AA09A106,2008AA092301)the National Nature Science Foundation of China(Grant Nos.50909025,51009040 and 51179035)
文摘Based on the deep analysis of the mathematical model of an autonomous underwater vehicle( AUV),comprehensive considerations are given to the coupling effect of AUV's longitudinal velocity on the other degrees of freedom. In the meantime,discussions are made on the influence of residual buoyancy and restoring moment.A novel S-plane controller established on sliding mode control( SMC) is hereby proposed in this study. The strengths of traditional S-plane controller including simple structure and easily adjustable parameters are maintained in the improved design while the weakness of unsatisfactory control effect at the time of high-speed operation is also overcome. Lyapunov function is introduced to make the stability analysis of the controller before it is successfully applied to the basic motion control of AUV-X. Then the comparative experiment test is carried out between the traditional S-plane controller and the novel S-plane controller. The effectiveness and feasibility of the novel S-plane controller established on sliding mode control in the AUV basic motion control is verified by the comparative analysis of experiment results.
文摘The stability of a gravity dam against sliding along deep-seated weak planes is a universal and important problem encountered in the construction of dams.There is no recommended method for stability analysis of the dam on deep-seated weak planes under earthquake condition in Chinese design codes.Taking Tingzikou dam as an example,the research in this paper is focused on searching a proper way to evaluate the seismic safety of the dam against sliding along deep-seated weak planes and the probable failure modes of dam on deep-seated weak planes during earthquake.It is concluded that there are two probable failure modes of the dam along the main weak geological planes in the foundation.In the first mode,the concrete tooth under the dam will be cut and then the dam together with part foundation will slide along the muddy layer;in the second mode,the dam together with part foundation will glide along the path consist of the weak rock layer under the tooth and the muddy layer downstream the tooth.While there is no geological structure planes to form the second slip surface,the intersection of the main and the second slip surface is 40 to 80 m downstream from dam toe,and the angle between the second slip surface and the horizontal plane probably be 25 to 45 degrees.
