Mechanical Analysis Of Pile Foundation In Slope

In mountainous cities, house constructions are usually built in pleasant places against mountains, which will inevitably lead to some pile foundations built in slopes. In addition, the pile foundations of bridges connecting the hill masses on two backs also need to be embedded in bedrocks with slopes or in soil masses. At present, such problems are common in engineering constructions, however, the researches on load-bearing mechanism of pile foundation are mainly aiming at pile foundations on flat ground at home, and the researches on pile foundations in slopes are very rare and even if the literatures referring to this problem can be numbered. On the basis of analyzing the analysis methods and researches carried out about pile-soil interaction, this paper sets up a coupling analysis model on pile-soil interaction and researches the mechanics characteristics of pile foundations in flat ground and in slopes of different angles. The main work done in this paper includes two aspects as follows: (1) Aiming at the pile-soil system in slope, the finite element program is compiled with the object-oriented programming language of C++. In order to simulate the characteristic of pile-soil interaction more profitably, the 16-node interface element is set up. The pile foundation in soil slope is analyzed by adopting the Duncan-Chang model (which is widely used at home and abroad) as the constitutive model of the program. Through analyzing of calculation examples, the distributing shapes of side resistance for piles in flat ground and in soil slopes with different angles are compared. (2) By using ANSYS, a general-purpose FEA software, the 3-D FEA on pile foundation in rock slope of different angles is carried out in this paper. In the calculation, the DP model is chosen to consider the non-linearity of rock and the status non-linearity of rock-structure interface adopts the surface-surface contacting element. In addition, the curve forms of side resistance of pile along the pile shaft in flat ground and rock slopes of different angles are determined through calculation examples. The main conclusions are as follows: (1) The side resistance curve of pile has obvious non-linear characteristic. The geotechnical parameters have relatively big influence on side resistance of pile. The side resistance curve of pile in rock slope and that of pile in soil slope are different in distribution form. (2) The side resistance of pile has a obvious share in load bearing. In slope of the same angle ,along with the increasing of pile top load, the side resistance of pile increases, the ratio of pile side resistance sharing the pile top load gradually decreases and that of pile base resistance sharing the pile top load gradually increases. In same load ,along with the increasing of angle the ratio of pile base resistance sharing the pile top load gradually increases and that of pile side resistance sharing the pile top load gradually decreases. (3) The side resistance of pile in slope and that of pile in flat ground are different in distribution trend. It is mainly expressed as follows: In flat ground, the values of pile resistance of the four sides are exactly the same. While in slope of the same angle, the resistance values of pile side near the slope surface, of pile side far from the slope surface and of the two pile sides are diverse from each other, each with different characteristic of distribution trend. (4) The load bearing mechanisms of pile foundation in slope of 30°and 60°show some differences and the distribution forms of side resistance curves are different. Along with the increasing of pile top load, the resistance value of each pile side increases but with different extent of increasement, of which the resistance value of pile side far from the slope surface is the greatest in increasement and the resistance values of the other pile sides are relatively small. (5) For vertical slope, the special circumstance of slopes, the resistance action of pile side near the slope surface is the smallest and the resistance actions of the other pile sides are relatively big, which is different with the distribution trend of side resistance of piles in slopes of 30°and 60°. (6) The change of slope angle has the greateat influence on the resistance distribution of pile side near the slope surface and has relatively small influence on that of the other pile sides. (7) The behaviors of pressure suffering of pile foundation in flat ground and in slopes of different angles are different. The side resistance of pile in soil slope and that of pile in rock slope are different in distribution trend. Only if the side resistance characteristics of pile foundation in the slope with different angles be well considered, can the characteristics of load bearing of pile foundation be exactly grasped.