Study On The Dynamic Response And Stability Analysis Of Layered Rock Slopes

With the rapid development of society and the implementation of western development strategy in China,a large number of geotechnical engineering has been built or will be built in the strong earthquake zone,rock slope failure induced by earthquakes is one of the most common and dangerous seismic-induced geo-hazards worldwide.Layered rock slope exist in the western area,its damage process and failure model not only has much to do with rock mass structure,and also is closely related to the seismic wave propagation.How to effectively estimate the stability of the slope in case of earthquakes is of great significance to ensure the smoothly constructing and safe use of the basic engineering construction.Shaking table test can directly reproduce the mechanical behavior of geological structures under seismic or synthetic dynamic conditions,and can reproduce of the deformation and destruction process of the physical model accurately.Discontinous deformation method(DDA)is a kind of dynamic discrete numerical method,which can simulate the discontinuous deformation behavior of jointed rock mass,and it has great potential to investigate the dynamic response of rock mass engineering.Based on the layered rock slope,shaking table test and DDA numerical method were combined to study the dynamic response and stability problems of the slope under earthquake action.The application of DDA numerical method in seismic analysis of rock mass engineering has been developed and improved.The main research contents and results are concluded as follows:(1)Shaking table tests have been performed to investigate dynamic response characteristics of two physical slope models with dip and anti-dip layered rock slopes containing two groups of rock joints with weak intercalations.To reasonably design the size of the model and mechanical parameters of model materials,the scaling coefficients are determined based on scaling theory.The basic physical and mechanical parameters of block material are determined using an orthogonal design method.The strength of weak intercalation is measured by shear tests.Factors such as rock structure,acceleration amplitude,frequency and waveform are considered to study the dynamic response characteristics.The tests reveal different failure mechanisms and failure modes between dip rock slope and anti-dip rock slope.(2)The DDA motion equation and contact theory are introduced,and the accuracy of the integration scheme of DDA is analyzed.The basic dynamic theory of DDA method including damping,boundary and dynamic load inputting problem are reviewed and extened researched.The DDA control parameters and the influencing factors of wave propagation are studied.(3)Comparison with the shaking table test model result,the DDA method is conducted to simulate the prototype of shaking table test model.Under different amplitudes loading,the dynamic response and failure mechanics of the prototype models are investigated to compare with the test results.The dynamic response characteristics of the prototype models are discussed under horizontal direction earthquake and vertical direction earthquake excitation.It reveals that the dynamic response of dip rock slope under horizontal direction seismic loading is stronger than under vertical direction,while the dynamic response of anti-dip rock slope under vertical direction seismic loading is stronger than under horizontal direction.(4)Based on the attenuation law of the dynamic friction coefficient with the cumulative displacement and relative velocity,a method for evaluating the slope dynamic stability is put forward considering structural plane degradation.The formulas for calculating the dynamic safety coefficient based on the concept of contact force and strength reduction are presented.(5)Bai He Tan Hydropower Engineering is located in seismically active zone,its left rock slope is a typical dip rock slope,which contains a variety of weak structural plane,the seismic stability analysis of the slope is particularly urgent.Based on the improved DDA numerical method,the degradation effect of the slopr control structure plane under seismic load,the failure mechanism and dynamic stability of the slope under Wenchuan wave excitation are analyzed.The results show that the slope is stable,while the rock masses formed by LS422,F146,F112,F17 and LS3319 weak structural planes happen large deformation,it presents obviously slip cracking deformation mode,but it tends to be stable in the end.The effect of the slope reinforcement is studied,it indicates that anchor structure can effectively reduce the displacement of the slope under seismic load,it is beneficial to the slope stability.