| Due to the existence of weak structural plane,bedding slope is easy to slide and cause huge economic losses under earthquake,so it is an important subject to study the reliability analysis of bedding slope under earthquake action.At present,Monte Carlo method,first order second moment method(such as center point method)and other methods are widely used to solve slope reliability.However,these methods have certain disadvantages.For example,Monte Carlo method uses exhaustive method to calculate reliability,which leads to too large amount of analysis and calculation,while the function of the first order second moment method is excessively simplified,which leads to large analysis error.Compared with Monte Carlo method,breitung method,as a second order second moment method,can calculate the slope reliability only once according to the process flow,which greatly saves the calculation amount.In terms of calculation accuracy,breitung method is more accurate than the first order first moment method because it expands the function into quadratic terms.If this method can be used in engineering practice,it can improve the calculation efficiency and ensure the calculation accuracy,and has strong practicability.In this paper,breitung method is introduced to solve the dynamic reliability of slope for the first time.Firstly,the accuracy of the reliability obtained by breitung method is verified by finite element numerical simulation.Then,the virtual excitation method is introduced to replace the time history analysis method to simulate random earthquake.Finally,the influence of various factors on slope reliability is studied.The main work and conclusions are as follows:(1)The calculation process of breitung method is expounded in theory,and the correctness of breitung method in theory is proved,and the concrete process of solving bedding slope feasibility by this method is summarized.(2)Combined with a slope engineering example,the finite element model of the slope is established by using the finite element software,and the appropriate constitutive model,boundary conditions and damping are selected.Then the static stress of each element of the structural plane is obtained under the action of gravity The conclusion of slip failure.Then the dynamic stress of each element is obtained by time history analysis method.Finally,breitung method is used to program to obtain the dynamic reliability time history curve.By comparing with the reliability time history curve obtained by Monte Carlo method,the accuracy of reliability calculation is verified.(3)In order to consider the randomness of the earthquake and improve the calculation efficiency,the virtual excitation method is introduced to replace the time history analysis method to simulate the random earthquake,and the breitung method is used to solve the dynamic reliability of the slope subjected to earthquake.By comparing the results with the results obtained by quasi-static method and time history analysis method,it is found that the method considers the dynamic characteristics of earthquake and can find the most unfavorable vibration of slope,which can simplify the analysis process and obtain more accurate results.(4)The influence of various factors on slope reliability is studied by changing the statistical eigenvalues and seismic parameters of structural plane soil parameters.The analysis shows that: with the increase of internal friction angle or cohesion variation coefficient of bedding structural plane,the slope reliability decreases;with the increase of seismic intensity,the slope reliability decreases;when the seismic intensity is small,the influence of earthquake duration on the reliability is small;when the earthquake intensity is large,the reliability changes greatly due to the change of earthquake duration. |
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