Theory Analysis Of Piles-diaphragm Wall Combined Foundation Under Lateral Concentrated Load

Piles-diaphragm wall combined foundation under the horizontal load as a new type of foundation,compared with the traditional pile under horizontal load,the pile diameter and pile number increased under the condition of passive earth pressure does not increase,in reducing the cost while ensuring the bearing capacity of the foundation level.The present research on pile and diaphragm wall foundation is less,the influence of the bearing performance of many factors,so far,bearing mechanism of pile and diaphragm wall foundation and deformation characteristics of the problem has not been solved very well.Based on the project of Shandong Electric Power Engineering Consulting Institute,this thesis makes a preliminary analysis and Research on the bearing capacity and deformation characteristics of the composite foundation by means of indoor model test and theoretical analysis.The main conclusions are:(1)Through the indoor model experiment,the displacement and bending moment of the composite foundation under horizontal load are analyzed.The results show that with the increase of load,the wall and the bending moment of pile,composite foundation top displacement and soil pressure are increased;combined the maximum bending moment of 1/2 extension in the direction of the depth of underground continuous wall and pile wall joints and the maximum bending moment;effective height of foundation;foundation is inclined slip and damage trend;the size of foundation can effectively increase the combination tilt limit combined foundation,enhance the stability of composite foundations;pile foundation and underground continuous wall of the horizontal bearing capacity of pile foundation is about 4 times of the same size.(2)Based on the principle of wall,pile,soil lateral deformation and the Rankine earth pressure formula analysis method is put forward a method for stability analysis of composite foundation under lateral concentrated load,by comparing with the model test results,preliminary verify the rationality of this calculation theory.(3)Using the m method,and combined with the calculation of MATLAB program,mainly to explore the horizontal load size,the width of the wall body,pile diameter size,soil properties and material elastic modulus and other factors influenced on deformation and internal force of combined foundation.Results show:The maximum displacement of the combined foundation is at the top of the foundation,and the maximum bending moment is at the wall and the pile’s rigid connection position;The size of the wall width and the diameter of the pile are all inversely proportional to the maximum displacement of the combined foundation,But when the wall width increases to 6m or pile diameter increases to 0.8m,the maximum displacement of the combined foundation decreases with the decrease of the maximum displacement;Soil resistance increases,the maximum displacement of the composite foundation decreases,the m value increases to 10MN/m~4,the deformation of the composite foundation tends to the fixed value,and the soil resistance has little effect on the internal force of the foundation;Elestic modulus of combined foundation have little influence on displacement and bending moment of foundation.