Research On Aseismic Analysis Method For Slopes Reinforced With Cantilever Stabilizing Piles Under Strong Earthquake

As a commonly used support structure in slope projects, stabilizing piles can effectively control the deformation and improve the stability of slope. Hence it is a hot spot in the geotechnical engineering research field. However, research on the aseismic design method of stabilizing piles in slope under strong earthquake is relatively lacking. The seismic damage investigation of5.12Wenchuan Earthquake indicates that many road slopes with piles were damaged and has severely affected the regular use of roads, which implicates that traditional aseismic analysis method has some drawbacks. Consequently, in order to optimize aseismic design method, this paper conducts studies on cantilever stabilizing piles in reinforced soil slope from following aspects:1) In order to get the reasonable anchorage depth, section dimension and foundation stiffness for the aseismic reinforcement of slope, based on the seismic acceleration tested by Wolong station during5.12Wenchuan Earthquake, this paper has discussed the influence of these key elements on the internal force and deformation of pile through dynamic analysis by FLAC software.2) Through dynamic finite element calculation, the lateral landslide thrust and position of action point behind the pile are derived for both debris slope and clay slope. It has discussed the distribution forms of slope pressure behind the pile and the corresponding change laws. The result reflects that the position of action point will shift upward and the slope pressure will grow and present segmental distribution during the earthquake. At the same time, the simplified distribution model is offered, which is convenient to be applied.3) Based on the upper bound theorem of limit analysis, the effective pile resistance under varied design factors of safety can be determined. Then, combined with the Newmark’s sliding block concept, the expressions for the yield acceleration and seismic permanent displacement can be deduced. It also discusses the influence of design factor of safety on the seismic permanent displacement of slope, and reaches the conclusion that the effective resistance and yield acceleration grows gradually as the factor of safety increases, but the seismic permanent displacement decreases by an exponential function.4) According to the lateral allowable bearing capacity of rock and soil mass around the pile, it employs the elastic subgrade reaction method to verify and determine the plastic anchorage area and divides the pile into loaded segment, plastic anchorage segment and elastic anchorage segment. Then, the formula of internal force and deformation of pile for every segment can be infered. based on which the logical elastoplastic aseismic calculation method can be determined.The primary results of this research, including mechanical characteristics of stabilizing piles under strong earthquake, the calculation method for permanent displacement and the optimizational aseismic design and calculation of stabilzing piles, could be offered as theoretical guidance and reference to some degree for aseismic design of soil slope reinforced with stabilizing piles.