Research On Interaction Between The Piles With Pre-stressed Anchor Cables And Soil

With a great deal of tall buildings and substructures constructed,the excavations are becoming more and more.The design and construction of the excavation are becoming more and more difficult.Now,the theories and the calculating methods of protecting design for excavation in the home and abroad chiefly include the limite quilibrium method,the subgrade reaction method and the finite element method.The limit equilibrium method cannot meet engineering design demands frequently as too much factors ignored,and the application is becoming littler and littler.The finite element method is mature in theory,but it is difficult to fix the earth model and the soil parameters,so being difficulty to be practice applied.The elastic subgrade reaction method is used more and more in recent years.But the study on it is not sufficient,so the method used now cannot consider the protecting structure-soil nonlinear interaction yet.Besides,the existing means to analyze the spatial effects of deep excavation are not practical,because too complicated or too simplified.For make the elastic subgrade reaction method to be consummated and explore the new practical means to analyze the spatial effects of deep excavation,the following main achievements are obtained by study in this dissertation:(l)To consider the nonlinear interaction between soil and the piles with pre-stressed anchor cables in soil layers for deep excavation designs,p-y curves of supporting pile and soil was proposed according to concentrated force spring model.Based on piles shaft defection differential equation of the general elastic subgrade beam and considering that the deformation of anchor is compatible with the anti-slide pile's deformation,differential equation of the piles with pre-stressed anchor cables to consider the nonlinear interaction is derived.Adopt finite difference method to calculate internal force and deflection of supporting piles.Finally,in comparison with the other methods,the calculated results of engineering sample indicate that this paper is satisfied for engineering calculation.(2)This paper establishes calculation procedures with Matlab.These procedures are used to calculate engineering example.After establishing a series of calculation modulars combining with the function of optimization of Matlab,this paper does optimization of engineering example.(3)The present situations of the deep excavation construction monitoring were analyzed. And the deep excavation construction monitoring considering the dual demands both displacement back-analysis of protecting structure—soil space nonlinear interaction and safety forecast was advanced.The monitored data can meet the demands of the displacement back-analysis by expanded the traditional construction monitoring of safety forecast,but the monitored contents and cost increased less.The monitored aims,observation system design principles,monitored basic requirements and monitored ready works were made definite.The problems such as monitoring points set up and data handled were studied emphatically.And suggest that the monitoring points set up on plane according to the deep excavation spatial effect laws,and on section according to soil layers and protecting structures status etc.