深部隧道围岩承载拱演变规律及影响分析

Variation Pattern of Surrounding Rock Bearing Arch of Deep Tunnel and Analysis on Its Impact

为研究深埋条件下隧道开挖后围岩承载拱的演变规律,通过承载拱力学模型推导深部隧道围岩承载拱内外边界的解析解,采用有限差分软件对不同围岩级别、不同埋深及不同侧压力系数条件下深埋隧道围岩承载拱的演变规律及各影响因素的耦合作用进行分析研究。结果表明:各因素对深部隧道围岩承载拱的影响程度从大到小依次为围岩级别、隧道埋深及侧压力系数;围岩级别直接决定了承载拱的范围大小,围岩条件越差,隧道开挖引起的应力重分布范围越大;承载区范围与隧道埋深基本呈线性关系,随埋深增加,承载拱内外边界均向围岩深部偏移;侧压力系数对承载拱形态演变影响最大,内外边界的形态特征随侧压力系数变化呈现出来的变形规律不尽相同。

In order to reveal the variation pattern of the surrounding rock bearing arch of deep-buried tunnel after excavation,the mechanical model for load-bearing ring is used to derive the analytical solution of the internal and external boundaries of the surrounding rock bearing arch of deep tunnel,and the finite difference software is used to analyze and investigate the variation pattern of the surrounding rock bearing arch of deep-buried tunnel under different surrounding rock grades,different buried depths and different lateral pressure coefficients and the coupling effect of the influencing factors.As the results indicate:The ranking of the factors in terms of their influence on the surrounding rock bearing arch of deep tunnel is surrounding rock grade>buried depth of tunnel>lateral pressure coefficient;the surrounding rock grade will directly determine the scope of the bearing arch,i.e.worse surrounding rock conditions will bring greater scope of stress redistribution induced by tunnel excavation;the scope of bearing area is largely in linear relation with the buried depth of tunnel,because as the buried depth increases,both internal and external boundaries of the bearing arch will shift toward the deeper part of the surrounding rock;lateral pressure coefficient imposes the greatest influence on the form variation of the bearing arch,where the morphological characteristics of the internal and external boundaries exhibit different variation patterns as the lateral pressure coefficient changes.