基于无限体中圆形隧洞的弹性解,结合卸荷扰动区与深部未扰动区的位移公式,推导洞室开挖卸荷区围岩的等效弹性抗力系数表达式,并通过算例对比分析,验证其合理性。研究结果表明围岩的等效弹性抗力系数与扰动区岩体弹性模量呈非线性关系,扰动区岩体质量弱化,弹性模量降低,泊松比增大,扰动区围岩的刚度和侧向约束能力降低,围岩的等效弹性抗力系数随之减小;相同开挖半径下,扰动区范围的扩大直接降低围岩承载能力,围岩的弹性抗力系数减小;在扰动区厚度一定的情况下,开挖半径越大,等效弹性抗力系数越小。说明隧洞围岩稳定是扰动区与深部未扰动围岩共同作用的结果,仅采用扰动区岩体参数计算围岩弹性抗力系数会过高地估算围岩的分载能力,采用围岩等效弹性抗力系数评价围岩承载能力更加合理。

The expression of equivalent elastic resistance coefficient of surrounding rock in excavation-disturbed zone is derived based on the elastic solution of circular tunnel in infinite elastic solid and the displacements of excavation-disturbed zone and undisturbed zone. The rationality of the expression is verified through case comparison. Results reveal that the equivalent elastic resistance coefficient of surrounding rock is in a non-linear relationship with the elastic modulus of disturbed zone. With the decrease of elastic modulus and increase of Poisson’s ratio, the stiffness, lateral restraint ability and equivalent elastic resistance coefficient of rock mass will decrease. Under given excavation radius, the extension of disturbed zone would reduce the bearing capacity and equivalent elastic resistance coefficient of rock; while under given depth of disturbed zone, elastic resistance coefficient decreases with the increasing of excavation radius. The results suggest that stability of surrounding rock was affected by the combined action of disturbed zone and undisturbed zone. Taking the rock parameters of disturbed zone only in the computation will lead to overestimation of bearing capacity of surrounding rock. Therefore, equivalent elastic resistance coefficient of surrounding rock should be considered for the rational estimation of rock’s bearing capacity.