非圆形地下洞室地层特征曲线近似构建法

An approximate building method of ground reaction curve for non-circular underground caverns

弹塑性地层特征曲线完整地描述了围岩对开挖的响应特征,是地下洞室稳定性分析及支护设计的关键,但目前仅圆形洞室具有完整的地层特征曲线解析形式,非圆形洞室需要通过复杂的数值方法拟合。为提高非圆形洞室计算效率,拓展解析法的适用范围,文中基于等代圆理论探讨了非圆形洞室近似解析地层特征曲线的构建方法。首先,利用数值分析,得到地下工程中常见非圆形断面在不同跨高比条件下,洞室周边围岩压力与变形的关系,建立基于数值分析结果的地层特征曲线;然后,基于和数值分析相同的初始条件,建立各种等代圆方法对应的近似地层特征曲线;最后,通过对比及相关影响因素分析,揭示不同工况下各种等代圆方法的适用性,为构建非圆形断面地下洞室地层特征曲线的最佳近似解析形式提供了一条简便有效的途径。

The elastic-plastic ground reaction curve completely describes the response characteristics of the surrounding rock excavation, which is the key to the cavern stability analysis and the support design. However, only the circular cavern currently possesses the integral analytical form of a ground response curve for the irregular cavern, and complex numerical methods are adopted. To improve the computational efficiency of the non-circular cavern and to expand the scope of the analytical method, the most appropriate equivalent circular method is discussed in this article when the approximate analytical GRC is built. Firstly, The numerical analysis method is used to obtain the relationship between the surrounding rock stress and the deformation of irregular caverns under different span ratios, and the corresponding GRC are established. Based on the same original condition with the numerical analysis, five equivalent circular methods are used to solve the corresponding approximate GRC. By contrasting, the applicability of various equivalent circular methods under different conditions is revealed. The results provide a simple way to build the best approximate analytic form of GRC for non-circular caverns.