The Settlement And Mechanical Analysis Of Concrete-core Sand-gravel Pile Composite Foundation

The application of concrete-core sand-gravel pile deep in soft soil reinforcement is still in the research stage,It has been applied in highway engineering and management of water conservancy projects successfully but both of theories and practices are in the initial stage, and it won't apply widely in the civil engineering.The theories of concrete-core sand-gravel pile composite foundation have been summed up in this paper,and a new formula which was used to calculate the settlement of composite foundation is put forward for reference. In addition, the three-dimensional model of concrete-core sand-gravel pile composite foundation was established to carry out numerical simulation. The major works of this paper are as follows:According to the introduction for compositions, mode of application, as well as the working method of concrete-core sand-gravel pile composite foundation,The theories of concrete-core sand-gravel pile composite foundation are cavity expansion theory and consolidation theory.This paper collected theoretical answers relation to cavity expansion theory, for the saturated clay, finishing the Cambridge model and Modified Cam-clay model of the theoretical solution.In addition, All of the pore water solution, consolidation degree of expression, calculation of vertical settlement of the soil when consolidated are Analysised with the principle of sand, a new formula for calculation of concrete-core sand-gravel pile composite foundation was based on the idea of the settlement was done.With the establishment of three-dimensional model, first, vertical stress and settlement changes of the pile, shell of sand-gravel and soil were calculated under the circumstances of the different core diameter and the same gravel pile shell thickness when flowing, And he relationship between the stress ratio of the pile, shell of sand-gravel and soil, also the situation of pore water which was pumping from the soil was done, Considering the impact of different permeability coefficient of soil and flowing time. Second, the same concrete pile-core diameter and the different sand-gravel shell thickness of the composite foundation has been researched.At last, Discussed the impact of the stress and settlement of concrete pile-core when different length reached the substratum.