Analysis On Characteristics Of Pile Foundation Influenced By Pile Side Cave In Karst Areas

With the rapid development of city and traffic, there are more and more construction projects in karst area. At the same time, the application of pile foundation is also more and more. But in the karst area, the geological condition is complicated and changeable, and the design and construction of the pile foundation have many problems. So in order to ensure the construction projects completed smoothly, it is necessary to analysis the feature of the pile foundation. At present, the research mostly focus on the situation that the karst cave in the bottom of the pile foundation in karst area, and there is little research on that the karst cave at the side of pile foundation, especially when the pile under horizontal load. But in practice, there are many pile foundation in such condition, so it is necessary to research the pile under horizontal load whose side has the karst cave.Based on the Nanjing-Guangzhou high-speed railway Segment from Litang west to Guiping, the paper builds the model with MIDAS-GTS numerical simulation software in the full understanding of the geological and the form of pile foundation, then analyses the influence of karst cave which at the side of pile on pile foundation. The model is analyzed from the following aspects, such as the diameter of pile, the length of pile, the diameter of cave, the depth of cave, the horizontal position of cave, the angle position of cave, the different of the filling. After data processing, the paper analyses the influence of different parameters on the pile foundation from the displacement of pile top, the load of pile top and the displacement of pile body, then obtains the conclusion. These conclusions have certain reference value for the design and construction of horizontal pile foundation in karst area. At the same time, based on the data of the simulation results,the grey correlation analysis measure is applied to analyze the sensitivity of factors that influence the stability of pile foundation. Finally, the results show that the ranking of sensitivity as follows: the diameter of cave> the angle position of cave> the diameter of pile> the depth of cave> the horizontal position of cave> the length of pile> the different of the filling. From this conclusion, the diameter of cave is the largest influence, the different of the filling is the minimum influence, and provide certain reference for the factors which one is the main influencing factors in the actual engineering.