卸载条件下二向不均等地应力场中圆形冻结壁弹性应力分析

为获得二向不均等地应力场中圆形冻结壁的受力变形规律,考虑开挖卸载工况,建立了冻结壁与围岩相互作用弹性力学模型,推导并用有限元软件验证了其解析解,且与传统加载模型进行了对比。着重分析了冻结壁内缘环向应力与径向位移的分布情况及其与各影响因素间的关系。研究表明:加载模型较本文卸载模型计算结果总体偏大;在冻结壁与围岩弹性模量的比值β较小时,考虑其相互作用可有效减小冻结壁的应力与位移;若地应力均匀系数λ较小,冻结壁内缘会出现环向拉应力,不利于其承载能力的发挥;卸载率、β、λ、冻结壁内外半径比均对冻结壁的应力、位移有较大影响,而泊松比的影响相对较小。本文计算模型能较真实地反映冻结壁的受力变形情况,研究成果对冻结壁的设计与施工具有一定的指导作用。

Elastic stress analysis on circular frozen wall in bi-directional unequal ground stress field under unloading condition

To obtain the stress and deformation of circular frozen wall in bi-directional unequal ground stress field, an elastic mechanical model of frozen wall interacting with surrounding rock has been es-tablished with the excavation unloading considered. The analytical solution has been derived and veri-fied by finite element software,which has also been compared with the traditional loading model. The hoop stress and radial displacement distributions in the inner edge of frozen wall have been analyzed emphatically as well as their relationship with different influencing factors. The results have shown that the calculation results of the loading model are overall larger than the unloading model. When the elas-tic modulus ratio β between frozen wall and surrounding rock has a small value, the consideration of their interaction can decrease the stress and displacement effectively. If the ground stress uniformity co-efficient λ is small enough, the tensile hoop stress will appear in the inner edge of frozen wall, which is not conducive to the full play of its carrying capacity. In addition, unloading rate, β, λ, and frozen wall’s radius ratio all have significant impact on the stress and displacement of frozen wall, while the influence of the Poisson’s ratio is relatively small. On the whole, the calculation model in this paper can really re-flect the stress and deformation of frozen wall, and the research findings can guide the frozen wall’s de-sign and construction.