| The bedrock surface slopes steeply in karst areas, and their bearing capacity are different, so it is necessary to study their stability. On the basis of preceding main results, a mechanic model of overburden-karstic free face with a weak structural plane is presented in this paper. As well as its impact on the stability of the overburden soil layer thickness, structural plane friction coefficient, structural plane angle, free face angle, structural plane height, the pile foundation diameter, the distance from the pile foundation to free face and the pile foundation depth in rock is simulated with computer. The stability of free face at the effect of the pile foundation end fixing pressure is analyzed and calculated by three-dimensional finite element method so as to study the relations between the pile foundation end fixing pressure and the above factors. On this basis, the regression equation of the relation between the pile foundation end fixing pressure and the overburden soil layer thickness, structural plane friction coefficient, structural plane angle, free face angle, structural plane height, the pile foundation diameter can be got by means of multivariate linear regression method, moreover, this regression equation is optimized by Stepwise multiple linear regression method. Finally, verification is done to 38 pile foundations in 5 engineering examples by this regression equation above-mentioned in order to verify the reliability of the regression equation. It may draw a conclusion that the calculated results coincide with the engineering fact.
|
PDF Full Text Request