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考虑空隙影响的岩石统计损伤模型研究

Study on statistical damage model of rock considering void effect

  • 摘要: 为得到岩石在不同围压作用下变形特性以及岩石空隙对变形损伤的影响,采用TAW-2000岩石试验系统对砂岩进行室内三轴压缩试验;构建考虑岩石空隙损伤的三轴压缩统计损伤模型,以及提出确定分布参数和空隙损伤影响系数的方法,通过模型曲线和试验曲线对比,验证建立损伤模型的正确性与合理性。结果表明:该模型对传统破坏模型引入空隙损伤影响系数可以较好地描述损伤演化,并能反映出三轴压缩试验曲线的软化特性。该模型对传统破坏模型引入空隙损伤影响系数可以较好地描述损伤演化,并能反映出三轴压缩试验曲线的软化特性。岩石在同一围压作用下的损伤变量的变化规律都是呈现出先增大后趋于稳定的趋势,这是由于岩石在荷载作用下内部原生裂隙会进一步发展、扩散,直至贯通为宏观裂缝,导致岩石发生变形破坏,后续试验岩石试样沿着破裂面滑移,最终使得岩石的损伤程度逐渐加剧。由拟合结果可知,建立的统计损伤模型可较好地反应岩石的变形特性,也可较为真实反映巷道围岩的变形情况,对实际工程中巷道围岩-支护体的设计具有指导意义,但是实际工程中围岩所受的三向应力大小各不相同,鉴于试验条件约束无法实现,故需要在以后研究中对岩石做真三轴试验,才能更好地反映实际地层开挖后围岩的受力、变形情况。

     

    Abstract: In order to obtain the deformation characteristics of rock under different confining pressures and the influence of rock voids on deformation damage, the indoor triaxial compression test was carried out on the sandstone using the TAW-2000 rock test system.A triaxial compression statistical damage model considering rock void damage was constructed, and a method for determining distribution parameters and void damage influence coefficients was proposed.By comparing the model curve and the test curve, the correctness and rationality of the established damage model were verified.The results show that the model can describe the damage evolution well by introducing the void damage influence coefficient to the traditional damage model.And it can reflect the softening characteristics of the triaxial compression test curve.This model introduces the void damage influence coefficient to the traditional failure model, which can describe the damage evolution well and reflect the softening characteristics of the triaxial compression test curve.The variation laws of damage variables of rocks under the same confining pressure all show a trend of increasing first and then tending to be stable.This is because the internal primary fractures of the rock will further develop and spread under the load.Until the penetration is a macroscopic fracture, the rock will be deformed and damaged.In the subsequent test, the rock sample slipped along the fracture surface, and finally the damage degree of the rock was gradually increased.It can be seen from the fitting results that the established statistical damage model can better reflect the deformation characteristics of the rock.It can also reflect the deformation of the surrounding rock of the roadway more realistically, which has guiding significance for the design of the surrounding rock-support body of the roadway in practical engineering.However, the magnitude of the three-dimensional stress on the surrounding rock varies in practical engineering.In view of the fact that the constraints of the test conditions cannot be realized, it is necessary to perform true triaxial tests on the rocks in the future research in order to better reflect the stress and deformation of the surrounding rock after the actual formation is excavated.

     

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