层状岩体是自然界中较为常见的岩体类型，相较于单一岩石来说，具有非均质性、各向异性等显著特点，其力学性质更为复杂。目前对于层状岩体的研究相对较少，理论尚不成熟。因此，开展软硬互层岩体的力学特性及损伤演化规律研究，对指导工程设计具有重要意义。本文主要采用室内试验与理论分析相结合的方法，利用相似材料制备软硬互层岩体，基于核磁共振技术对软硬互层岩体的孔隙结构进行分析，开展单轴压缩试验及三轴压缩试验，分析软硬互层岩体强度特征及破坏模式，基于Weibull分布统计强度理论，建立软硬互层岩体的损伤本构模型。本文的主要研究结果如下：

（1）采用水泥、石膏粉及石英砂材料，通过配比试验，制备不同力学性质的单一岩石。选取预期目标强度的配合比制备层状岩体，利用不同角度的垫块钻取不同节理倾角的标准试块。制备了两种组合形式（硬-软、硬-软-硬），五种节理倾角(0°、10°、30°、45°、60°)的层状岩体试样。采用核磁共振技术对层状岩体试样的T₂谱分布、谱面积、孔隙度及孔径分布进行分析，孔隙结构主要以微小孔隙为主，试样孔隙分布较为均匀。

（2）对层状岩体试样开展单轴压缩试验，其强度规律随节理倾角0° 60°的变化呈现为先减小后增大的趋势，破坏特征由劈裂破坏转变为剪切破坏。并且在单轴压缩试验中辅以声发射技术，监测单轴压缩试验的声发射特征及试样裂隙扩展情况。对层状岩体试样开展三轴压缩试验，两层岩体强度规律随节理倾角的变化为先增大后减小，而三层岩体强度规律随节理倾角的变化为逐渐减小，受围压的影响，破坏特征主要以剪切破坏为主。通过对比两组试验，表明围压对层状岩体试样的强度及破坏特征的影响较为显著。

（3）通过引入Weibull统计强度理论建立损伤变量，并将损伤变量引入岩石本构方程中，构建统计损伤本构模型，对试验曲线的峰前阶段进行描述。通过理论曲线与试验曲线进行比较，验证了模型的合理性。通过分析节理倾角及厚度比对损伤变量的影响，揭示了节理倾角与厚度比对损伤变量影响的敏感程度，节理倾角对损伤变量的影响较大。

Layered rock mass is a common type of rock mass in nature. Compared with single rock, it has significant characteristics such as heterogeneity and anisotropy, and its mechanical properties are more complex. At present, there are relatively few studies on layered rock mass, and the theory is still immature. Therefore, it is of great significance to study the mechanical properties and damage evolution law of soft and hard interbedded rock mass for evaluating the stability of rock mass engineering and guiding engineering design. This paper mainly adopts the method of combining laboratory test and theoretical analysis, using similar materials to prepare soft and hard interbedded rock mass, analyzes the pore structure of soft and hard interbedded rock mass based on nuclear magnetic resonance technology, and carries out uniaxial compression test and triaxial compression test. In the experiment, the strength characteristics and failure modes of the soft and hard interbedded rock mass were analyzed, and the damage constitutive model of the soft and hard interbedded rock mass was established based on the Weibull distribution statistical strength theory. The main findings of this paper are as follows:

Using cement, gypsum powder and quartz sand materials, single rocks with different mechanical properties were prepared through the ratio test. Select the mix ratio of expected target strength to prepare layered rock mass, and use different pads to drill standard test blocks with different joint inclination angles. There are two combinations of layered rock samples (hard-soft, hard-soft-hard), and each combination corresponds to five joint dip angles (0°, 10°, 30°, 45°, 60°) The T₂ spectral distribution, spectral area and porosity of the layered rock samples were analyzed by nuclear magnetic resonance technology, which showed that the sample preparation effect was good, and the pore structure was mainly composed of tiny pores.

The uniaxial compression test was carried out on the layered rock samples, and the strength law with the change of the joint inclination angle was a "U"-shaped distribution that first decreased and then increased, and the failure characteristics changed from splitting failure to shearing failure. In addition, the acoustic emission technology is supplemented in the uniaxial compression test to monitor the acoustic emission characteristics of the uniaxial compression test and the crack expansion of the sample. The triaxial compression test was carried out on the layered rock mass sample. The strength law of the two-layer rock mass first increased and then decreased with the change of the joint inclination angle, while the strength law of the three-layer rock mass was gradually decreased with the change of the joint inclination angle. Due to the influence of confining pressure, the failure characteristics are mainly shear failure. By comparing the mechanical characteristics of the two groups of tests, it is shown that the confining pressure has a significant influence on the strength and failure characteristics of the layered rock samples.

The damage equation is established by introducing Weibull statistical strength theory, and the damage variable is introduced into the rock constitutive equation to construct a statistical damage constitutive model to describe the pre-peak stage of the test curve. The rationality of the model is verified by comparing the theoretical curve of the model with the experimental curve. By analyzing the effects of joint inclination and thickness ratio on damage variables, the sensitivity of joint inclination and thickness ratio to damage variables is revealed. The results show that the joint inclination has a great influence on the damage variables.

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