脆性土石混合体单轴压缩特性的影响因素研究

摘要

土石混合体在我国分布广泛且力学性质差异极大,研究其单轴压缩特性的影响因素至关重要.借助量纲分析,阐明了土石混合体单轴压缩特性与各影响因素间的无量纲关系.提出了一种块石随机生成技术,可产生指定级配的随机块石系统.借助连续-非连续数值模拟方法CDEM(Continuum Discontinuum Element Method),探讨了具有一定结构性的脆性土石混合体材料的宏观力学特性及其影响规律,并重点分析了该类土石混合体的含石量、土石交界面强度与其宏观本构曲线、单轴抗压强度以及破坏模式的对应关系.研究结果表明,随着含石量的增加,脆性土石混合体的宏观单轴抗压强度迅速减小,含石量超过15％之后,单轴抗压强度基本不变.相同含石量及块石分布的情况下,随着交界面比强度的增大,宏观单轴抗压强度逐渐增大;当交界面比强度大于20时,单轴抗压强度基本不变;当交界面比强度小于1时,主要出现贯穿整个试样的裂缝;当交界面比强度大于1时,主要在试样中上部出现局部的压剪破碎.%Rock and soil aggregate(RSA)is widely distributed in China and the mechanical properties are extremely different in one place from another,so it is important to study the influencing factors of uniaxial compression.With the help of dimensional analysis,the non-dimensional relationship between the uniaxial compression characteristics of RSA and the influencing factors is clarified.A stochastic generation technique of rock block is proposed,which can produce stochastic block system with specified gradation.With continuum-discontinuum element method(CDEM),the macro mechanical properties and evolvement laws of brittle RSA with structural feature is discussed,and the macro constitutive law,uniaxial compressive strength and failure mode of brittle RSA with different rock contents and interface strengths are analyzed.The results show that,with the increment of rock content,the macro uniaxial compressive strength decreases rapidly ;however,when rock content exceeds 15％,the uniaxial compressive strength is almost unchanged.With the same rock content and rock distribution,with the increment of interface strength,the macro uniaxial compressive strength increases gradually ;when the relative interface strength exceeds 20,the uniaxial strength remains constant.When relative strength of interface is less than 1,the penetrating crack will appear throughout the sample ;and when the relative strength is larger than 1,local compressive shear failure will occur near the middle and top of the sample.