A Simulating Experimental Study on Crack Healing and the Formation of High Pore Fluid Pressure in Faults of Middle Crust
详细信息
- 责任者：Han Liang (State Key Laboratory of Earthquake Dynamics ; Institute of Geology ; China Earthquake Administration ; Beijing 100029 ; China) ; Zhou Yongsheng
- 刊名：Chinese Journal of Geophysics
- 出版年：2013
- 卷期：56(1)
- 关键词：地壳 ; crust ; 高温高压实验 ; high temperature-high pressure experiment ; 流体 ; fluids ; 四川 ; Sichuan Province
- 页码：p.91-105
- 图表：illus., 2 tables, 70 refs.
- 分类号：0400
- issnNo：ISSN0001-5733
- isbnNo：CN11-2074/P
摘要
Sublithostatic pore fluid pressure in faults cutting the middle crust is considered to trigger slip on the high-angle reverse fault slip for the Wenchuan Ms8.0 earthquake,the mechanism of which is suggested to be related to crack healing.We conducted microcrack healing experiments on Carrara marble samples with different water contents to reveal the formation conditions of high pore fluid pressure using a molten-cell solid medium triaxial apparatus under high temperature and pressure.The experiments were designed to be three types as A,A+B and A+B+C,respectively.All the samples were fractured at room temperature in phase A,leading to conjugate fractures as the result of brittle deformation,and then healed at a constant temperature of 600 ℃,confining pressure of 700 MPa and a strain rate of 10-6s-1 in phase B,causing a transition from cataclastic flow to plastic deformation.Finally,we simulated a dilatation by reducing the axial stress instantaneously,and then loading again with the same strain rate to examine the degree of crack-healing by comparing the ultimate strength of stress-strain curves in phase C.The microstructures of samples after deformation and the stress-strain curves show that the dynamic recrystallization can heal the micro-cracks and pore,and the presence of water can enhance the process of the dynamic recrystallization.Our experiments suggest that higher water content and the larger strain are favorable to form high pore fluid pressure in a fault.
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