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结构面是影响岩体弹性模量的主要因素。基于岩体结构面参数统计,结合岩体应变能推导出的节理岩体本构关系,能够真实地反映岩体弹性模量的弱化和各向异性。在此基础上,以吉图珲铁路隧道围岩为例,研究了岩体弹性模量特征及影响因素。结果表明,该岩体弹性模量的弱化和各向异性程度随应力轴线与结构面法线的夹角而变化,并在夹角值为54.5°时达到最大;同时,岩体弹性模量的弱化与结构面内摩擦角和黏聚力成反相关,与结构面平均半径和密度呈正相关。当结构面半径超过3 m时,岩体弹性模量弱化趋于稳定。应力环境对弹性模量同样有影响,围压的增大,可使岩体弹性模量增大,同时减小了其各向异性和弱化的程度。当围压达到2.32 MPa时,各向异性及弱化现象消失。
Structural plane is the main factor affecting the elastic modulus of rock mass. Based on the statistical data of rock mass structural plane parameters and the constitutive relation of joint rock mass derived from the strain energy of rock mass, the weakening and anisotropy of rock mass mass can be truly reflected. On the basis of this, taking the surrounding rock of Jitutuo railway tunnel as an example, the elastic modulus of rock mass and its influencing factors are studied. The results show that the degree of anisotropy and the weakening of the elastic modulus change with the angle between the stress axis and the normal to the structural plane and reach the maximum at an included angle of 54.5 °. Meanwhile, the elastic modulus Weakening is inversely related to the in-plane frictional angle and cohesion, and is positively correlated with the average radius and density of the structural plane. When the structural surface radius exceeds 3 m, the elastic modulus of the rock mass tends to be stable. The stress environment also affects the elastic modulus. When the confining pressure increases, the elastic modulus of the rock mass increases, and the anisotropy and the degree of weakening of the rock mass decrease. When the confining pressure reaches 2.32 MPa, the anisotropy and weakening disappear.