高温高压下红河断裂带断层泥力学性质的研究

断层泥在室温高压下的应力-应变曲线呈非线性、线性等阶段性变形,在高温高压下则呈非线性变形,两者均表现出渐进破坏。含水量、矿物成分和温压条件对变形特征和破坏强度有重要影响。曲线的初始弹性模量小于有效弹性模量。断层泥在温度T≥400℃和σ_3≥300MPa时发生岩化,据此岩化温压条件可估计出未岩化断层泥存在深度将不超过10—15km。由于断层泥具渐进破坏特征,故在高温高压条件下断层泥有利于断层活动呈现稳滑

THE MECHANICAL PROPERTIES OF FAULT GOUGE OF HONGHE FAULT ZONE AT HIGH TEMPERATURE AND PRESSURE

The mechanical properties of fault gouge of Honghe fault zone were studied at temperatures up to 600℃, confining pressures up to 700 MPa and strain rate of 4.4×10-5/s, At room temperature and high pressure the stress-strain curves of gouge were characterized by linear and non-linear stages of deformation, at high temperature and pressure the non-linear deformation was presented in the curves. The failure strength of gouge increased with increasing confining pressure at the same temperature, and de creased with increasing temperature at the same confining pressure. As the content of calcite in gouge was more than 20 %, the failure strength at high temperature decreased with increasing confining pressure, this anomalous change in mechanical behavior of gouge may be related to the plastic deformation and solid-gas transition induced by calcite and to the decreasing effective pressure caused by increasing pore fluid pressure. The a-coustic emission activity occurred in the gouge specimen during deformation, but no stress drop was observed in the stress-strain curve. After the differential stress reached the failure strength, the gouge specimen underwent a gradual failure process. The initial and effective elastic modules were determined from the stress-strain curves of gouges, the former were smaller than the latter. The gouge was lithified at T≥400℃ and σ3≥300 MPa confining pressure, according to the lithifying conditions of temperature and pressure, the existing depth of clayey gouge does not exceed 10-15 km, Because the failure of gouges took a gradual character, it is favorable for the active fault with gouge to slide stably