Seismic Stability Analysis Of Slope Based On Theory Of Slip Line Field

After the Wenchuan earthquake, the problem of soil solp stability analysis under seismic action has become an important topic in domestic geotechnical engineering field. In the soil solp stability analysis under seismic action, the determination of slip surface is very important. Circular slip surface method, as an experience method used widely at present, will produce large error in the analysis. While the slip line field theory, based on equilibrium equation, yield condition and force boundary conditions, can be used to caculate the stress, displacement and velocity distribution of the plastic zone and elastic zone of the slope and then the slid surface can be searched, which is more scientific and reasonable than the circular arc sliding method. In this thesis, the stability analysis of soil slope based on slip line field theory under seismic action has important theoretical and practical significance.In this thesis, theoretical analysis and numerical simulation are used to study the seismic stability of soil slope. The main contents are as follows:Firstly in this thesis, the dynamic finite element method is used to calculate the stress of the slope under earthquake action and the slip line field theory is used to to search the slip line. The safety factor of each slip line is calculated, among all the silp line, the slip line with the minimum safety factor is the most dangerous slid surface. A numerical example analysis is given to show the reasonable of this method.Then the Monte Carlo Method is used to analyze soil slope dynamic reliability under seismic action, and the minimum average dynamic reliability index is proposed to evaluate the seismic slope stability. The result of caculaion shows that if only to calculate the slope safety coefficient under seismic action, without considering the random parameters of soil slope, will make the calculation results on the safe side.At last the influence of seismic wave amplitude, earthquake wave frequency, and variation coefficient of soil cohesion and internal friction angle on slope shear zone and dynamic reliability are analysed based on the methold introduced in the thesis. The result shows that with the increasing of seismic amplitude, the slope is more and more unstable. The more closer between the earthquake frequency and the self vibration frequency of soil slope, the more unstable the slope is. The increasing of variation coefficient of soil cohesion and internal friction angle will decrease the stability of soil slope under seismic action.The work and conclusions of this thesis have very important guiding significance to the practical engineering.