基于极限分析法的溶洞顶板极限承载力研究

发布时间：2019-07-29 15:49

【摘要】：针对下伏溶洞顶板极限承载力问题,提出了两种顶板极限承载力计算方法;方法 1:假定冲切体为圆锥台,由极限平衡法得出极限平衡状态下破坏面上拉应力与剪应力同时作用时的极限承载力;方法 2:假定冲切体是以一个未知曲线为母线的旋转体,由极限分析法求出其母线形式以及极限承载力的表达式,通过求偏导获得了溶洞顶板的极限承载力。同时进行了下伏溶洞顶板极限承载力室内模型试验,得到了1~5倍桩径顶板厚度下溶洞顶板基岩的破坏模式以及相应的极限承载力,实测结果与理论吻合良好。研究表明:溶洞顶板厚度为1D至3D(D为桩径)时,发生冲切破坏,破坏模式是以曲线为母线的旋转体,4D时发生撕裂+冲切复合破坏,5D时基岩出现塑性破坏。在溶洞顶板厚度为1D~4D时,同一跨径比条件下,极限承载力随顶板厚度的增加呈线性增长,达到5D时,顶板承载力与基岩基本一致。
[Abstract]:In order to solve the problem of ultimate bearing capacity of roof of underlying cave, two calculation methods of ultimate bearing capacity of roof are put forward, method 1: assuming that the punching body is conical platform, the ultimate bearing capacity of tensile stress and shear stress on failure surface under ultimate equilibrium is obtained by limit equilibrium method. Method 2: assuming that the punching body is a rotating body with an unknown curve as the bus, the expression of the bus form and the ultimate bearing capacity is obtained by the limit analysis method, and the ultimate bearing capacity of the cave roof is obtained by calculating the partial derivation. At the same time, the laboratory model test of the ultimate bearing capacity of the roof of the cave is carried out, and the failure mode of the bedrock of the roof of the cave under the thickness of 1 脳 5 times the diameter of the roof and the corresponding ultimate bearing capacity are obtained. The measured results are in good agreement with the theory. The results show that when the thickness of cave roof is 1D to 3D (D is pile diameter), punching failure occurs, the failure mode is a rotating body with curve as busbar, tear punching composite failure occurs at 4D, and plastic failure occurs at 5D. When the thickness of cave roof is 1D~4D, the ultimate bearing capacity increases linearly with the increase of roof thickness under the same span ratio. When the roof thickness reaches 5D, the roof bearing capacity is basically the same as that of bedrock.
【作者单位】：湖南科技大学岩土工程稳定控制与健康监测湖南省重点实验室;湖南省农林工业勘察设计研究总院;
【基金】：国家自然科学基金资助项目(No.51208195) 岩土工程稳定控制与健康监测湖南省重点实验室开放基金资助(No.E21618)~~
【分类号】：TU473.1

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