| Due to the high bearing capacity, low cost, good seismic resistanceperformance and simple construction, the rock-socketed pile is widely used in solutions of all basic foudation problems. The bearing capacity of rock-socketed pile is mainly composed of three parts, which is non rock-socketed segment of the soil around the pile side friction resistance, rock-socketed segment side friction resistance of rock block and the end resistance of the pile. The large amounts of measured data show that, the top load of rock-socketed pile is mainly borne by the side friction and tip resistance of rock-socketed pile. However, at the present stage, people know of the side friction of rock-socketed pile is not deep enough, although there are some scholars and experts conducted a study on rock-socketed pile side friction, but also did not have a more unified calculation method and intreractive theory.At first, carried on the simple elaboration and comparison of calculation method of the side friction of rock-socketed pile in related specifications, and introduced in detail the sliding dilatancy mechanism of pile-rock interface,which show that the pile side friction resistance mechanismat pile-rock interface can be divided into bond damage, sliding dilatamcy and shear slipping.According to the specification of rock-socketed pile the calculation method of pile side friction and sliding dilatancy mechanism,we know the main factors which influence the pile side friction is included rock-socketed depth,intensity of the bedrock,pile diameter and roughness of hole side.The indoor model test is carried out based on two 2m diameter pile in situ test of Chongqing cuntan port three-phase project.The tests were selected two different kinds of rock-socketed depth( 3.8D and 7D),and considering two kinds of bedrocks(moderately weathered mudstone and sandstone).The tests are analysised the pile side friction distribution along the rock-socketed depth and rock-socketed depth,rock strength on rock-socketed pile side friction effects.On this basis, using ANSYS finiteelement software for modeling and analysis of the laboratory model, results demonstrate the feasibility of the model and reliability of the data.Also by finite element software ANSYS to simulate the main influence factors which affect the side friction of large diameter rock-socketed pile. The results found that the distribution cure of pile side friction of the rock-socketed segment along the rock-socketed depth is nonlinear,and its for the twin peaks form,with the first peak is moves down when the rock-socketed depthand diameterrock-socketed pile increases, and the peak position of the moving range within the scope of rock-socketed depth of 0~3D; the second peak is gradual degradation with the rock-socketed depth and diameterrock-socketed pile increases; under the same load of pile top,the greater rock-socketed depth and diameterrock-socketed pile,the smaller settlement of pile top; through the analysis we know the peak period of side friction of rock-socketed segment needed 5~15mm displacement of pile top. In the same pile top load and rock-socketed depth, the greater intensity of the bedrock,the smaller settlement value of pile top, and the bigger limit value of pile side friction, and the more obvious of bimodal pattern of pile side friction distribution curve. According to the results of model tests and numerical simulation,we also got some other conclusions which can provides effective reference for rock-socketed pile design and construction. |
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