The Application Of Composite Foundations In Dalian Subway Karst Foundation

With the expanding scale of the foundation and development of technology, the formation of the composite foundation theory is a big improvement for the theoretical foundation. From the single pile to the multiple piles, scholars have developed more scientific, reasonable and targeted deal in view of the different actual engineering. In the face of the complex geological conditions, the advantage of multiple composite foundation is more apparent. Because of the complex bearing and deformation characteristics of the composite foundation, the analytical method can’t completely reflect the actual problem. So the numerical calculation method is the necessary means.Despite the current composite foundation has made the big achievement, the theory can’t satisfy the need and has a lot of problems. Based on the line2of Dalian subway, the paper contains the design of the foundation reinforcement project and the numerical simulation about the influence between the parameters and deformation. The main contents and features of the paper appear below:(1) According the geotechnical engineering investigation report of dalian subway qianshan station and the actual engineering characteristics, the paper identifies the multiple composite foundation reinforcement solutions which is formed with the CFG pile and high pressure jet grouting pile.(2) When doing the multiple composite foundation theory calculation, the traditional method only does the area of the weighted calculation without taking into account the pile lengths and pile end resistance effects. The paper considers both the pile and soil lateral friction role and end resistance function, so the composite modulus can be with high accuracy.(3) With the Drucker-Prager elastic-plastic model, it established the numerical analysis model using the ANYSY analysis software. According to the several problems and deformation characteristics of the mechanism, there is a new model establishment method. Through the simulation in different load and parameters, it gets the law of the composite foundation bearing and deformation.