岩溶地区嵌岩桩桩基竖向承载力有限元分析

Finite Element Analysis on the Vertical Bearing Capacity of Rock-socketed Pile in Karst Area

利用有限元对岩溶顶板上嵌岩桩桩基的工作性状进行了数值模拟,分析了加载过程中桩顶荷载与桩顶沉降的关系及地基中塑性屈服区分布,并据此确定桩基竖向承载力,在此基础上研究了溶洞高度、跨度、顶板厚度、围岩及嵌岩深度对桩基承载力的影响。研究结果表明:岩溶地区嵌岩桩嵌岩深度宜浅不宜深;围岩强度对桩基承载力的影响最为明显,顶板厚度及跨度影响较大,洞室高度影响最小;当顶板达到一定深度时,溶洞对桩基承载力的影响已经不明显,设计时一律按当地经验要求的溶洞顶板最小厚度进行基础设计,有时造成较大浪费。

The finite element method is used to simulate the bearing properties of rock-socketed piles on the karst roof. Based on the analysis of the relationship between pile load and pile settlement and ground plastic yield zone distribution, the vertical bearing capacity of the pile is determined. Furthermore, the influence factors of ultimate bearing capacity of pile are investigated such as the height, span, roof thickness, rock property and socketed depth. The calculating results show that： short socketed depth is suitable in karst area, rock property has the most obvious effect on ultimate bearing capacity of pile, and then are roof thickness, span and height, and the karst cave height has minimal impact on ultimate bearing capacity of pile. When the roof reaches a certain depth, the impact of the cave has not been seen on the pile bearing capacity. All according to the local experience required the minimum thickness of roof, the design may sometimes lead to a greater waste.