Research On Retaining And Protecting Structure With Double-Row Piles

In this thesis the known work about retaining and protecting structure with double-row piles is summarized, and the several common calculation methods about it at present are emphasisely introduced. On the basis of that, the calculation model about retaining and protecting structure with double-row piles is improved, and the earth pressure which the fore-pile and the rear-pile bear in different arrangements is given seperately, so is the modified calculation model. Then the internal force of the pile body is calculated with large-scale mathematical calculation programme Matlab. According to the comparision between the calculation results and that of the model test, the modified calculation model proves to be reasonable.The whole process of the model test for the retaining and protecting structure with doule-row piles is also fomulated. According to the model test, the excavation process of the foundation is simulated, and the internal force of the pile body and the horizonal displacement on the top of the piles are measured, which provides a series of data for the analysis of the structure and the verification of the given calculation model of the retaining and protecting structure.According to the series of the calculation schemes which take into account many factors, such as the distance between the two rows and the embedded depth of the double-row piles, the influences on the working behavior of the retaining and protecting structure with double-row piles are studied as well. By the contrast of the calculation results, the working mechanism of the retaining and protecting structure with double-row piles is summarized and some valuable conclusions are gotten which can do some use to the engineering practice and theory research.The main conclusions of this thesis are the following: 1. On the condition of the same number of piles, the maximum of the bending moment of the double-row piles is much less than that of the cantilever pile and the distribution of the former is more even than the latter; 2. Greater changes take place in the bending moment diagram of the rear-pile body when the length of the rear-pile decreases, yet the changes have little effect on the whole retaining and protecting structure; 3. Thechange of the distance between the two rows has big effect on the whole structure. When it is in 2-4 times of the diameter of the pile, the structure itself can adjust the bending moment of the pile body very well. Yet when it increases to 6 times, the retaining and protecting effect of the structure is closely to that of the sustaining pile on the top.