深埋碳质千枚岩力学特性及其能量损伤演化机制

为揭示深埋碳质千枚岩的遇水软化损伤特性和微层理结构的各向异性，开展了不同层理角度和不同含水状态下的千枚岩力学试验。并基于能量损伤演化机制分析了层理角度和含水状态对千枚岩储能机制和释能机制的影响。研究结果表明：深埋碳质千枚岩的各向异性特性和遇水软化效应是千枚岩内部的沉积层理、层状薄片矿物和高黏土矿物成分导致的固有特性；其破坏机制及其强度各向异性主要受控于层理面间的弱胶结作用，这种弱面效应会随着围压的增大而降低；千枚岩遇水后其力学特性和脆性被弱化，宏观破坏角增大，表现出张拉破坏减弱，剪切破坏增强；基于弹性能和耗散能比例曲线的S型变化规律与能量演化规律，将岩石的渐进破裂演化过程划分为4个阶段，并采用能量损伤演化理论探讨了I型和II型两种典型岩石破坏方式的能量机制及其损伤演化机制；层理方向和含水状态对千枚岩的储能能力具有较大影响，其中层理方向对千枚岩的释能机制和损伤破裂演化机制影响不大，而千枚岩的储能与释能机制则对含水状态的变化更为敏感。

Mechanical properties and energy damage evolution mechanism of deep-buried carbonaceous phyllite

In order to study the anisotropy of the water-softening damage characteristics and the micro-layered structure of deep-buried carbonaceous phyllite, rock mechanical tests of carbonaceous phyllite were conducted under different bedding directions and different water contents. Based on the energy damage evolution mechanism, the influences of bedding direction and water content on the energy storage and energy release mechanism of phyllite are analysed. The results suggest that the anisotropic characteristics and water-softening effects of deep-buried carbonaceous phyllite are inherent characteristics attributed to sedimentary beddings, layered lamellar minerals and high content of clay minerals inside the carbonaceous phyllite. The failure mechanism and the anisotropic strength of phyllite are dominated by the weak cementation between the bedding surfaces. This weak-surface effect increases with the decrease of confining pressure. With the increase of water content, the mechanical properties and brittleness of phyllite are weakened, and the macroscopic failure angle is increased, which results in the decrease of tensile failure and the increase of shear failure. Based on the energy evolution mechanism and the S-shaped curves between elastic energy and dissipated energy, the gradual failure process of rocks is divided into four stages. Based on the energy damage evolution mechanism, the energy mechanism and its damage evolution mechanism of rocks’ two typical failure modes, type I and type II, are studied. It is found that the bedding direction and water content both have great influence on the energy storage capacity of phyllite. The bedding direction has a small influence on the energy release mechanism and damage evolution mechanism of phyllite. The energy storage and energy release mechanism of phyllite are more sensitive to water content than to bedding direction.