Test And Studying Of Large-diameter Rock-socketed Pile Bearing Capacity And The Strengthen Effect Of Tip Resistance To Shaft Resistance

In recent years, with the implementation of the western development strategy, a large number of new types of buildings are springing up, especially high-rise, super high-rise buildings and long span bridges.so it posed the higher requirments for foundation.Because of high bearing capacity,small deformation,simple construction, cost economic,rock-socketed piles as an important basic form of large buildings have been widely used in the project. Although the application of rock-socketed pile more early, its stress mechanism and work characteristics exist many issues to further investigation. Such as the problem about a reasonable depth of embedded in rock, the distribution patterns of rock-socketed frictional resistance,bearing calculation of rock-socketed pile, the bearing characteristics of rock-socketed piles under the effect of loading and so on. In addition, the phenomenon about soil properties of the pile (rock) tips influencing the play of pile side resistance on a certain range has aroused more and more attention from scholars, but so far, the research and test information in this area are even less.Through testing on-site vertical static loading, this article analysis the load transfer mechanism of rock-socketed pile, pile side resistance and tip resistance distribution, and the ratio between the two sharing, and found that pile side lateral shear resistance strengthening effect is also obvious phenomenon in this test Using finite element soft ANSYS, the numerical simulation are more accurate and results are more similar with testing results, on this basis, this article also discussed load transfer mechanism of the single pile under vertical loading of soil in the same pile, different pile end rock (support layer) and the phenomenon of reinforced effect about the tip resistance to side resistance. Finally, at the end of the vertical static load testing, doing level static load testing obtain the curves of horizontal force-time-horizontal displacement, force displacement gradient and stress and moment distribution of pile shafe,and analysis the mechanism and characteristics of level loading of rock-socketed piles. The results showed that rock-socketed pile side friction in the commitment to the process of pile top load played an important role, and in the friction, the upper part of the role of soil can not be ignored; side effect of blocking the contralateral enhanced resistance not only occurs In the pile near the pile top soil there, strengthening effect of the occurrence of pile tip resistance of rock strength and size to play a relationship; level of bending moment under the load concentrated in the 0～6m range 6m moment the following small piles under lateral reinforcement cage without full configuration, only the bending moment concentration is laid horizontal force can resist the moment generated.Includes:1. the load-settlement of single-pile;2. column load transfer characteristics of single-pile shaft;3. Distribution single pile side resistance, the ratio of side friction and end resistance distribution;4. Finite element soft ANSYS as a tool to establish the model of different rock pile under strength condition, analyze the phenomenon of the load transfer mechanism and the strengthening effect5. Through level load testing of the pile, analysis bearing behavior of rock-socketed piles and the influencing factors at horizontal load, provide the basis of conducting a reasonable level of loaded rock-socketed pile design.