巷道开挖围岩能量释放与偏应力应变能生成的分析计算
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摘要
巷道开挖,围岩能量释放,同时在围岩中产生偏应力。围岩应力是原岩应力与偏应力的叠加,偏应力或偏应力能控制岩体破坏。在静水压力p0和岩体体积应变为0的条件下,利用文[1]在弹性、非线性软化本构模型导得的巷道围岩应力分布表达式,用重积分计算了围岩弹性区和软化区中的偏应力应变能Ud,证明了Ud可以简捷地用地应力p0关于巷壁位移ua做一次积分再乘巷壁周长的途径来得到,阐述了该计算途径的原理。巷道开挖过程围岩释放的能量等于围岩压力pa关于ua的积分乘巷壁周长。由此,可通过p0～ua曲线、pa～ua曲线所围面积的几何形式,表示围岩偏应力能、围岩弹性能释放量随ua变化的情况。所得研究结果可以深化围岩由于开挖产生的力学响应及挖成后围岩工况规律的认识。
Surrounding rock energy is released in company with tunnel excavation;and in the meantime deviatoric stress is brought in surrounding rock.Surrounding rock stress is the superposition of stress in virgin rock mass and deviatoric stress.The deviatoric stress or its strain energy dominates the breakage of rock mass.On condition that the hydrostatic pressure p 0 and the volumetric strain of rock mass is equal to zero,by using the stress distribution expressions of surrounding rock which are educed on base of the constitutive model that its elastic and nonlinear softening segment linked glossily in paper [1],and using multiple integral,the strain energy of deviatoric stress,U d,is calculated in the elastic and softened zones of surrounding rock.It is proved that U d can be deduced concisely by way of integrating the ground stress pa with respect to the displacement of tunnel wall u a,and multiplying by perimeter of tunnel wall,and the principle of the calculation approach of Ud is expatiated.The energy released by surrounding rock in the process of tunnel excavation is equal to the product of perimeter of tunnel wall and the integral of the surrounding rock pressure p a with respect to ua.Thereby,the circumstances of deviatoric stress energy and the released elastic energy in surrounding rock in response to ua can be expressed by the geometrical form that the area enclosed by the curves p 0-ua and pa-ua.The acquired findings can deepen the understanding of mechanical response of surrounding rock owing to tunnel excavation and operating condition of surrounding rock after tunnel excavation.
Surrounding rock energy is released in company with tunnel excavation;and in the meantime deviatoric stress is brought in surrounding rock.Surrounding rock stress is the superposition of stress in virgin rock mass and deviatoric stress.The deviatoric stress or its strain energy dominates the breakage of rock mass.On condition that the hydrostatic pressure p 0 and the volumetric strain of rock mass is equal to zero,by using the stress distribution expressions of surrounding rock which are educed on base of the constitutive model that its elastic and nonlinear softening segment linked glossily in paper [1],and using multiple integral,the strain energy of deviatoric stress,U d,is calculated in the elastic and softened zones of surrounding rock.It is proved that U d can be deduced concisely by way of integrating the ground stress pa with respect to the displacement of tunnel wall u a,and multiplying by perimeter of tunnel wall,and the principle of the calculation approach of Ud is expatiated.The energy released by surrounding rock in the process of tunnel excavation is equal to the product of perimeter of tunnel wall and the integral of the surrounding rock pressure p a with respect to ua.Thereby,the circumstances of deviatoric stress energy and the released elastic energy in surrounding rock in response to ua can be expressed by the geometrical form that the area enclosed by the curves p 0-ua and pa-ua.The acquired findings can deepen the understanding of mechanical response of surrounding rock owing to tunnel excavation and operating condition of surrounding rock after tunnel excavation.
引文
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[2]郑颖人.岩土塑性力学原理[M].重庆:中国人民解放军后勤工程学院出版社,1998.
[3]郑雨天.岩石力学时弹塑粘性理论基础[M].北京:煤炭工业出版社,1988,237―238,241―245.
[4]贾乃文.粘塑性力学及工程应用[M].北京:地震出版社,2000.
[5]Kachanov L M.塑性理论基础[M].北京:人民教育出版社,1982,147―148.
[6]何满潮.软岩工程力学[M].北京:科学出版社,2002.
[7]Maranini E,Brignoli M.Creep behavior of a week rock:experimental characterization[J].International Journal of Rock Mechanics and Mining Sciences,1999,36(1):127―138.
[8]Sato T,Kikuchi T.In-situ experiments on an excavation disturbed zone induced by mechanics excavation in neogene sedimentary rock at Tono Mine[J].Central Japan.Engineering Geology,2000,(1-2):97―108.
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