基坑支护排桩之间净距离的大小对桩后土体的受力与变形会产生影响,采用连续介质研究方法无法研究相邻桩之间土拱的形成对桩后土体的影响.本文采用颗粒流软件PFC 2D对桩间水平土拱的形成、发展及失效整个过程进行数值模拟,分析了桩间距对土拱效应的影响,并对比了方形桩和圆形桩在产生土拱效应方面的差异.本文研究从微观方面揭示了土拱效应形成及破坏的机理,分析发现土拱的最大承载力、桩的最大荷载分担比随桩间净距与桩径比值的增大而减小,并且在相同的桩间距情况下,方桩受力性能优于圆桩.因此,在进行支护桩设计时,应选择合理的桩型和桩间距从而达到优化设计、节省投资的目的.%The net distance between pit piles will affect the force and deformation of the soil behind pile, using continuous medium method can not study the impact of soil arching between adjacent piles on soil behind pile. In this paper, the particle flow code in two dimensions (PFC2D) simulates the entire process of formation, development and failure for the level arch of soil between piles, and analyzes the effects of pile spacing on soil arching, and contrasts the square pile with circular pile in soil arching effect differences. The results reveal the soil arching effect formation and destruction mechanism from the microscopic aspect. The analysis finds that the maximum capacity of of the soil arching, the maximum pile load-sharing ratio decreases with increase of the ratio of the net spacing between piles to the pile diameter; in the case of the same pile spacing, the force performance of square pile is clearly superior to round pile. Therefore, during the design of supporting piles, we should choose reasonable pile section shape and pile spacing so as to optimize the design and save investment.
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