非线弹性岩石割线模量与最大最小主应力关系模型

    Relationship models between secant modulus and maximum and minimum principal stresses of nonlinear elastic rocks

    • 摘要: 假设岩石为各向同性的非线弹性体,通过将岩石应变分解为线性的弹性应变和非线性的孔隙应变,建立和验证单轴压缩下岩石压密-线弹性阶段应力σ-应变ε关系的双曲线和负指数模型,推导岩石割线模量Egσ1σ3关系模型,以计算深埋直墙拱形隧洞围岩应力。结果表明:①岩石σ-ε双曲线、负指数模型计算与实测数据的相关系数均在0.999以上,相关性较高;②Egσ1σ3关系的模型参数,包括初始模量、极限模量和极限孔隙应变,可由单轴试验确定;③隧洞围岩拉应力集中条带的形状和位置与试验中板裂裂纹的基本一致,结果对认识深部围岩板裂机理具有一定启示。

       

      Abstract: Stress-dependent elastic modulus (SDEM) of rocks is an important factor affecting the stress distribution of deep surrounding rocks. To quantitatively describe the rock SDEM, assuming rock as an isotropic nonlinear elastic body, its strain is decomposed into linear elastic strain and nonlinear pore strain. A hyperbolic model and a negative exponential model of the stress(σ)-strain(ε) relationship during the compaction-elastic stage under uniaxial compression are established and verified. The model of the rock secant modulus (Eg) and σ1, σ3 is derived and used to calculate the stress of the surrounding rock of deeply buried straight wall arch tunnel. The results show that the correlation coefficients between the calculated values of the hyperbolic and negative exponential models and the measured data are all above 0.999, indicating a level of high correlation. The parameters of the models, including initial modulus, limiting modulus, and limiting pore strain, can be determined by uniaxial tests. And the shapes and positions of the tensile stress concentration bands in the surrounding rock of the tunnel are basically consistent with those of the slabbing observed in the tests, which is enlightening for understanding the mechanism of slabbing in deep surrounding rock.

       

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