Experimental Study On Structural Mechanics Mechanism Model Of Pile Front Constrained Pile Slab Support

The support structure of pile front constrained pile slab is a new type of support structure designed by the Wang Kai team according to the theoretical achievements of the previous truss pile slab retaining wall and bundled anti-slide pile.As a new type of support structure,it increases the soil range of the pile side to provide the embedded force,improves the structure’s ability to resist the slope thrust,and avoids the uplift of the soil before the pile.The purpose of this paper is to propose this kind of support structure,and to compare and analyze the model test and cantilever support structure model test of the constraint pile before the pile,to obtain the deformation of the two structures after the force and the stress distribution of the soil before the pile,and to analyze the moire stress and shear strength envelope of the two structures in the same coordinate system.The main research contents and achievements of this paper are as follows:(1)The support structure of pile front constrained pile slab is put forward,and its structure composition,design concept and internal force analysis are briefly introduced.The support structure of pile front constrained pile slab is mainly composed of pile body and the pile slab,the constraint plate and the rib plate are composed of four parts;the design idea is mainly to increase the constraint plate,so that the embedded soil in front of the pile presents a three-way force state on the force model,so that the moire stress circle is far away from the shear strength envelope,so as to enhance the embedding capacity of the soil before the pile.;The internal force analysis is carried out according to the method of elastic foundation beam.(2)Design model test,make cantilever support structure and pile front constrained pile plate support structure model.Compared with the size of the ruler 1:10,the model is graded and loaded by the loading device,and the soil pressure at each position of the soil before the pile is measured by the soil pressure box,and the pile top displacement of the model is recorded in the loading process by micrometer.Three-axis tests were carried out on the embedded soil in front of the pile to obtain the internal friction angle of the soil before the pile and the physical and mechanical parameters such as adhesion force.(3)This paper deals with and analyzes the test data of the model test,and compares the difference between the support structure of the constraint pile and the load effect of the cantilever support structure before the pile,and obtains the following conclusion:the maximum bearing capacity of the support structure of the constrained pile plate before the pile is larger than the maximum bearing capacity of the cantilever support structure,About 1.57 times times that of it;under the same force,the pile top displacement of the cantilever support structure is much larger than that of the constrained pile slab support structure,and the maximum displacement of the top pile is about 2.57 times times.Through the treatment of the additional stress X direction,Y direction and total stress of the two kinds of support structure pile before the soil,The stress change cloud map and the stress distribution law with loading are obtained.(4)This paper compares the position relationship between the moire stress circle and the shear strength envelope drawing of the two supporting structures,and analyzes the change of its cascade loading.The concept of damage degree of embedded soil in front of pile is defined,and the damage degree of two kinds of support structures is obtained by calculation,and the damage degree of two kinds of support structures is compared and analyzed.