基于多对数螺旋曲线破坏机构的富水软岩隧道开挖面支护应力分析
Supporting Pressure for Tunnel Face in Water-rich Weathered Rock Masses Based on a Multi-log Spiral Failure Mechanism
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摘要: 为了避免对胡克-布朗准则进行任何线性化处理, 将广义胡克-布朗(generalized Hoek-Brown, GHB)强度准则直接引入到开挖面稳定性分析中, 基于极限分析理论构建了富水地层浅埋隧道开挖面多对数螺旋线破坏机构。在考虑孔隙水压力的作用下, 推导出能量平衡方程, 得到开挖面极限支护应力表达式, 并且通过程序优化得到支护应力最优上限解。在此基础上, 分析了GHB强度参数、孔隙水压力系数、岩土体重度以及隧道埋深比对开挖面稳定性的影响。最后通过归一化处理得到不同情况下的开挖面极限支护应力稳定性图表, 通过该图表能够快速便捷地获得富水地层隧道开挖面维持稳定性所需的极限支护应力, 为盾构隧道初步设计提供理论依据。Abstract: To avoid introducing the generalized Hoek-Brown (GHB) strength criterion into the stability analysis of tunnel face directly by any linearization of Hoek-Brown strength criterion, this paper constructed a multi-log spiral failure mechanism for shallow buried tunnel excavation face in water-rich strata based on the limit analysis theory. Considering the existence of pore water pressure, the expression of the critical supporting force was derived from the tunnel face energy balance equation, and the optimal upper bound solution of the supporting pressure can be obtained through the optimization. Consequently, the influence of the GHB strength parameter, pore water pressure, rock mass unit weight, and the tunnel depth ratio on the stability of tunnel face were analyzed. Finally, a series of stability charts of the most critical supporting pressure of the tunnel face were presented to obtain the supporting pressure of tunnel face conveniently. This work provides a theoretical basis for the preliminary design of shield tunnel in water-rich stratum.