为定量评价开挖损伤对地下压缩空气储能(CAES)硐室力学响应的影响,建立考虑围岩初始损伤的衬砌-围岩结构弹性应力解析理论模型。首先,基于现场声波测试数据,采用指数函数表征钻爆开挖引起的围岩损伤因子及变形模量的径向非线性衰减规律;进而,根据平面应变假设与轴对称力学条件,建立关于径向位移的变系数控制微分方程,通过变量代换将其转化为标准合流超几何方程,从而推导出无衬砌及有衬砌2种工况下应力场的 Kummer 函数解析解。利用 Abaqus 软件建立考虑开挖扰动区(excavation damage zone, EDZ)非线性特性的有限元模型,通过在 Geostatic 分析步中预设初始应力场实现地应力平衡,验证解析理论的有效性。研究结果表明: 1)EDZ 内围岩模量的径向衰减打破了经典弹性解的应力分布单调性,环向应力最大值由硐壁处向岩体深部转移(算例中位于距硐壁0.2 m 处),呈现明显的“非峰值硐壁”特征; 2)衬砌的施加能显著改变围岩的受力状态,有效降低主应力差与拉应力水平,防止围岩发生剪切或受拉破坏; 3)应用该解析模型,以衬砌及围岩保持弹性状态为准则,可高效确定硐室的最大安全运行内压(算例中为17.5 MPa)。
To quantitatively evaluate excavation damage effects on the mechanical response of underground compressed air energy storage caverns, an analytical elastic stress model is established for the lining-surrounding rock structure considering initial damage in surrounding rock. First, based on insitu sonic test data, an exponential function is adopted to describe the radial nonlinear attenuation of the rock mass damage factor and deformation modulus induced by drilling-and-blasting excavation. Subsequently, under the plane strain assumption and axisymmetric conditions, a governing differential equation with variable coefficients for radial displacement is derived. Through variable transformation, the equation is converted into a standard confluent hypergeometric equation, yielding Kummer function analytical solutions for the stress fields of unlined and lined cases. A finite element model considering the nonlinear characteristics of the excavation damage zone (EDZ) is established using Abaqus. The insitu stress equilibrium is achieved by presetting the initial stress field in the geostatic step, thereby verifying the validity of the proposed analytical theory. The results show that: (1) The radial attenuation of rock mass modulus within the EDZ disrupts the monotonic stress distribution given by the classical elastic solution. The maximum tangential stress shifts from the cavern wall to the deep rock mass (located 0.2 m from the cavern wall in the numerical example), presenting a distinct “off-wall peak” feature. (2) The installation of lining markedly alters the stress state of surrounding rock, effectively reducing the principal stress difference and tensile stress level and preventing shear or tensile failure of surrounding rock. (3) The proposed analytical model efficiently determines the maximum safe operating pressure of the cavern (17.5 MPa in the numerical example), provided that both the lining and surrounding rock remain elastic.