The Research On The Effect Of Karst Cave On The Stability Of Retaining Pile

In the karst terrain, it is necessary to tack the influence of karst cave on the stability of pile into consideration. Many research works have been carried out on the effect on vertical bearing piles, but on the horizontal bearing piles, there are almost no attempts at home and abroad. This paper selects retaining pile that has karst caves in the surrounding as the research object, using numerical analysis method to study the effect of karst cave on the stability of retaining pile.According to the relative position of cave and retaining pile in karst area, the mechanical analysis model of retaining pile and cave is divided into three kinds. The first kind of model is the cave in bearing layer under the retaining pile’s bottom; the second model is the cave in the active region of retaining pile; the third model is the cave in the passive region of retaining pile. Various factors of the effect on the stability of retaining pile are considered and analyzed through numerical calculation including the size and shape of cave, the relative position of cave and pile, the pile embedded depth, the pile length and diameter, the thickness of overburden layer and the excavation depth. Each calculation model is parted into 5 subtypes according to the thickness of overlying soil layer and the value of mechanical analytical parameters in the subtypes is taken from the orthogonal test. Using this models, this paper try to find the critical safety distance of cave and retaining pile through the establishment of criterion of cave stability. Through calculation, it shows the influence of karst cave on the retaining pile is week when the soil layer is thinner and when the soil layer is thick, it has influence. In the influence part, the equation of the critical safety distance and influencing factors are given through multiple linear regression method and is verified by engineering examples. The research results provide a foundational technical basis for solving the problem of stability of retaining piles in karst area and formulating relevant article of specification.