强震作用下考虑岩石塑性应变梯度的地下隧道失稳分析
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摘要
本文首先引入岩石塑性应变梯度理论。地下隧道受开挖的影响,岩石的原岩应力重新分布,靠近隧道岩石变形局部化,往往出现塑性变形区。作者进一步论证了,靠近隧道岩石在建立地下震动作用下的数学力学模型时须考虑塑性应变梯度。进而从地下隧道弹塑性区内抽象出一个单元体,这个单元体在地震横渡作用下受力状态必然是纯剪应力状态,并假设岩石的力学本构关系为双线性,建立了单元体在地震横波作用下受力状态必然是纯剪应力状态,并假设岩石的力学本构关系为双线性,建立了单元体数学力学模型,推导出软化区的宽度为α(α=2πl)。基于上述,最后解释了地下隧道失稳破坏的力学机理。
In this paper, the gradient theory of rock plastic strain was introduced. Dealt with the digging effect of underground tunnel, the primitive stress of rock is redistributed and the deform ation of the rock alongside underground tunnel is localized. The necessity of considering gradient of the rock plastic train that establishes mathematics-mechanics model of vibration near tunnel rock was demonstrated. Abstracting an element from the extent of the underground tunnel in elasto-plastic region, only pure shearing stress is existed under the action of secondary wave. Assuming that the element is under the effect of secondary wave, the breadth of softening area is α(α = 2πl). Based on the above, the lose damage of underground tunnel is demonstrated.
In this paper, the gradient theory of rock plastic strain was introduced. Dealt with the digging effect of underground tunnel, the primitive stress of rock is redistributed and the deform ation of the rock alongside underground tunnel is localized. The necessity of considering gradient of the rock plastic train that establishes mathematics-mechanics model of vibration near tunnel rock was demonstrated. Abstracting an element from the extent of the underground tunnel in elasto-plastic region, only pure shearing stress is existed under the action of secondary wave. Assuming that the element is under the effect of secondary wave, the breadth of softening area is α(α = 2πl). Based on the above, the lose damage of underground tunnel is demonstrated.
引文
[1] 潘一山,徐秉业等.岩石塑性应变梯度与Ⅱ类岩石变形行为的研究.岩土工程学报,1998,21(4) :65-68
[2] 郭增建、秦保燕.震源物理.北京:地震出版社,1979
[3] Fleck N A, Hutchison J W. A phenomenological theory for strain gradient effects in plasticity. J Mech Solids, 1994, 41(12) : 1825-185;
[4] De. Borst, et al. Gradient-dependent plasticity: Formation and algorithmic aspects. Intemational Joumal for Numerical methods in Engineering, 1992,35: 521-539
[2] 郭增建、秦保燕.震源物理.北京:地震出版社,1979
[3] Fleck N A, Hutchison J W. A phenomenological theory for strain gradient effects in plasticity. J Mech Solids, 1994, 41(12) : 1825-185;
[4] De. Borst, et al. Gradient-dependent plasticity: Formation and algorithmic aspects. Intemational Joumal for Numerical methods in Engineering, 1992,35: 521-539
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