随着深部地下空间的开发，深部岩体的问题显得愈发重要，复合岩体作为地下工程中常见的工程对象，开挖时经常遇到动力扰动问题，如爆破或钎杆冲击等，所以对复合岩体的动力学研究意义重大。本文通过相似材料制备了软硬组合岩体试样，利用分离式霍普金森压杆试验（Split Hopkinson Pressure Bar,简称SHPB）研究了不同厚度比以及不同荷载作用面下软硬组合岩体的力学特性和破坏模式。通过数值模拟分析了冲击荷载下软硬组合试件内部裂隙发育过程。引入了Weibull分布统计强度理论，结合D-P岩石强度准则推导了软硬组合岩体统计损伤本构模型。主要研究内容及成果如下：

（1）本文通过一定配比的水泥、石膏粉、石英砂等材料制作所需的类岩石试件，通过控制浇筑时间将两种不同强度的类岩石材料凝结为研究所需的软硬组合岩体试块，并进行了基础物理力学性质的测定。

（2）对软硬组合岩体试件开展SHPB试验，在冲击荷载作用下，试件的应力峰值会随着硬岩占比的增大而增大。同一组试件的荷载作用面不同，动态抗压强度也会不同，硬岩面冲击的抗压强度要高于软岩面冲击的抗压强度，并且随着硬岩占比增加两者差距会逐渐减小。

（3）利用PFC^3D-FLAC^3D耦合建模的方式对软硬组合岩体试件单轴冲击压缩进行数值模拟，结果表明试件破坏模式为张拉和剪切的混合型破坏，内部裂隙首先出现在两端及层理面附近，随后由撞击面向层理面发育，同一试件由硬岩面冲击时的裂隙发育速度和裂隙总数都明显大于软岩面冲击。

（4）将损伤模型与开尔文体并联得到了考虑损伤效应与应变率效应的软硬组合岩体损伤本构模型，对模型中各个参数进行了敏感度分析，计算了各个参数对本构关系的影响，最后通过模型的理论曲线与试验曲线相比较，验证了模型的合理性。

With the development of deep underground space, the problem of deep rock mass is becoming more and more important. As a common engineering object in underground engineering, layered rock mass will be subjected to dynamic disturbances such as drill rod impact and blasting during excavation. Therefore, it is of great significance to study the dynamics of soft and hard combined rock mass. In this paper, the soft and hard composite rock mass samples were prepared by similar materials. Through the Split Hopkinson Pressure Bar(SHPB) test, the mechanical properties and destroy modes of the soft and hard composite rock mass under different thickness ratios and impact directions were studied. The development process of internal cracks in soft and hard composite specimens under impact load was analyzed by numerical simulation. By introducing the Weibull statistical fracture theory and combining the D-P rock strength criterion, the damage constitutive model of soft and hard combined rock mass is derived. The main research contents are as follows :

(1) In this paper, cement, gypsum powder and quartz sand are used proportionally to make the required rock-like materials. By controlling the pouring time, two kinds of rock-like materials with different strength are condensed into the soft and hard combined rock mass test blocks required for the study, and the basic physical and mechanical properties are measured.

(2) The SHPB test was carried out on the soft and hard composite rock specimen. Under the impact load, the peak stress of the specimen will increase with the increase of the proportion of hard rock. The loading surface of the same group of specimens is different, and the dynamic compressive strength is also different. The compressive strength of hard rock surface impact is higher than that of soft rock surface impact, and the gap between the two will gradually decrease as the proportion of hard rock increases.

(3) The PFC-FLAC coupling method is adopted for the numerical simulation of uniaxial impact compression of soft and hard composite rock specimens. The results prove that the specimen destroy mode is a mixed failure of tension and shear. The internal cracks first appear at both ends and near the bedding plane, and then develop from the impact to the bedding plane. The crack development speed and the total cracks number in the same specimen impacted by the hard rock surface are significantly greater than those impacted by the soft rock surface.

(4) By paralleling the damage model with Kelvin body, the damage constitutive model of soft-hard composite rock mass considering damage effects and strain rate effects is obtained. The sensitivity analysis of each parameter in the model is conducted, and the influence of each parameter on the constitutive relation is discussed. Finally, the model rationality is verified by comparing the theoretical curve with the experimental curve.

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