The Limit Analysis Ofseismic Staility Of Slopes And Retaining Structures In Earthquake Areas

The west area of China is mountainous and valleys region with extremely complex geomorphology and geology in the high intensity area for earthquake.With the rapid development of the construction of basic facility and the strategy implementation of the development of western regions,more and more highway and high-speed railway was needed to pass through the seismic areas and fault region.With the further development of urbanization construction and the construction land increasingly nervous,slope excavation was unavoidable to suit construction land needs.Therefore,the research of seismic stability evaluation methods is very significance for the infrastructure construction in the western China.In this paper,the plastic limit analysis of slope and retaining structures stability under the seismic load is systemically studied.The linear Mohr-Coulomb failure criterion and the non-linear Heok-Brown failure criterion were adopted for soil slopes and rock slopes separately.The two-dimensional and three-dimensional failure mechanisms of slope and retaining structures were established by pseudo-static andpseudo-dynamic method calculation.The seismic stability and permanent displacement of slopes and retaining structures explored.Some outcomes are drawn below.1.According to the kinematic limit approach and slices method,the evaluation methods of seismic slopes and retaining structures stability were presented basing on composite curved surface failure mechanism.The disintegration degree of soil and rock can be considered in this presented method,and it can be used to determine the potential sliding surface and discriminate slope stability.2.The seismic response of slopes was researched with three different failuremechanisms,which including logarithmic spiral and composite curved surface and curvilinear conical failure surface.The slope stability and permanent deformation during earthquakes were compared among three different failure mechanisms,and the influence of factors was discussed.3.The new combined anti-slide structure of pre-stressed rope anti-slide retaining wall was presented,and the computer models were established for cohesionless and c-φ backfill.Based on the kinematical approach of upper bound theorem,the collapse mechanism is investigated by the wall-rope-soil system.The yield acceleration factor and the corresponding inclination of failure surfaces can be estimated once the seismic acceleration threshold for slide is exceeded.The force exerted on the per unit width of sliding mass by pre-stressed rope and the embedded depth was analyzed emphatically.4.The analysis of retaining walls with broken-line back surface was complicated because of the retaining wall bilinear surface characters.Based on Coulomb’s earth pressure theory,the active earth pressure of the retaining walls with broken-line back surface was researched in the framework of the limit analysis theory subjected to earthquake.Then the multivariate function to calculation seismic active earth pressure,which can take account to the occurrence of the second fracture surface condition,is established and optimized by mathematical method using pseudo-static andpseudo-dynamic approach.The example was studied on influences of various parameters on seismic active earth pressure and it can be reduced active earth pressure coefficient due to the occurrence of the second fracture surface.5.This paper presents a simple method to evaluate the seismic stability of L-shape retaining walls with long and short heels.It can predict the positions of slip surfaces once the seismic acceleration threshold for slide is exceeded.Based on the wall-soil system collapse mechanism,the equation for expressing critical limit-equilibrium state was employed to define yield acceleration factor which contains two variables.The critical conditions of long and short heels were discussed.6.Based onIto and Matsui to calculateearth pressures on a row of passive piles,seismic response of 2D and 3D slopes reforced by anti-slide piles was researched.The optimal and effective location of a row of piles was presented by the calculation of the whole and local slope stability.7.The kinematic approach of limit analysis is used to analyze the stability of rock slopes reinforced by pre-stressed anchorage with Hoek-Brown strength criterion.The non-linerar failure criterion can be transformed by the tangential line method.The yield acceleration and permanent displacement of reinforced 2D and 3D rock slope with pre-stressed anchorage under seismic is investigated.The optimal location and inclinationand effective location ofrock slopes reinforced by pre-stressed anchorage were obtained.