张雷,
何昌荣,
周永胜
中国地震局地质研究所, 地球动力学国家重点实验室, 北京 100029

基金项目: 国家自然科学青年基金项目（41404144），国家自然科学基金项目（41874218）资助


详细信息

作者简介: 张雷, 男, 1985年生, 博士, 副研, 从事岩石摩擦实验和地震过程模拟研究工作.E-mail:zhanglei@ies.ac.cn

中图分类号: P312

收稿日期:2018-12-28
修回日期:2019-04-23
上线日期:2020-02-05

Experiments on frictional properties of phyllosilicate-rich mylonite under hydrothermal conditions

ZHANG Lei,
HE ChangRong,
ZHOU YongSheng
State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China



MSC: P312

--> Received Date: 28 December 2018
Revised Date: 23 April 2019
Available Online: 05 February 2020


摘要
摘要:为探索断层岩石摩擦特性对于断层力学性质的影响，我们采集了龙门山汶茂断裂韧性剪切带中的富含层状硅酸盐矿物的糜棱岩样品进行了水热条件下摩擦滑动实验研究.实验在三轴压机之上完成，实验温度为100~600℃，有效正压力100 MPa，孔隙水压分别为30 MPa和130 MPa.为获得摩擦滑动的稳定性参数（a-b），剪切滑移速率在1.22 μm·s^-1，0.244 μm·s^-1和0.0488 μm·s^-1之间切换.实验发现在200~500℃的温度范围内，摩擦系数随着温度的增加而显著增大（约0.56~0.72）.在200~300℃范围内，随温度的升高糜棱岩的摩擦滑动表现出由稳定的速度强化向不稳定速度弱化转变的趋势.在有效正压力不变的情况下，孔隙水压的增大会促进糜棱岩的摩擦滑动在500~600℃温度范围内由不稳定的速度弱化向稳定的速度强化的转变.实验给出的断层在原地深度处的脆性和塑性变形机制的转变，有助于理解断层深部的地震成核机制以及成核的温压条件.
关键词: 层状硅酸盐/
糜棱岩/
摩擦强度/
地震成核/
孔隙水压

Abstract:To investigate the influence of temperature and pressure on the frictional sliding behavior of typical fault rocks, we collected phyllosilicate-rich mylonite from a ductile thrust zone of the Wenmao fault in the Longmen Shan area. Frictional experiments were carried out under temperature of 100~600℃, effective normal stress of 100 MPa, and pore pressure of 30 MPa and 130 MPa. To obtain velocity dependence of friction, frictional slip rates were set as 1.22 μm·s^-1, 0.244 μm·s^-1 and 0.0488 μm·s^-1, respectively. The results indicate a significant increase of friction coefficient (about 0.56~0.72) of the mylonite with temperature at 200~500℃. Mylonite samples show a transition from initial velocity-strengthening behavior to velocity-weakening behavior at 200~300℃, and velocity dependence of friction coefficient on pore pressure. At effective normal stress of 100 MPa and temperature of 500~600℃, the increase of pore pressure can trigger the transition of mylonite from unstable velocity-weakening to stable velocity-strengthening.The laboratory-derived brittle-ductile transition in phyllosilicate-rich mylonite provides new insights into mechanisms of earthquake nucleation in the deep fault.
Key words:Phyllosilicate/
Mylonite/
Frictional strength/
Earthquake nucleation/
Pore pressure



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