正应力和含水率对花岗岩断层泥摩擦特性和声发射特征的影响

doi:10.3969/j.issn.0253-4967.2024.06.007

摘要/Abstract

摘要：

正应力和含水率的扰动可能诱发断层不稳定滑动。文中对采自新丰江水库附近断裂带的花岗岩样品开展了速率阶跃(1~100μm/s)和滑动-保持-滑动(10~3 000s)摩擦实验, 且全程进行了声发射观测, 研究了不同有效正应力(0.5~20MPa)和含水率(0%~25%)对花岗岩断层泥摩擦特性的影响。实验结果表明, 花岗岩断层泥随有效正应力增大由速率弱化(5MPa以下)向速率强化转变, 应力降减小; 随着含水率升高, 速率强化程度减弱, 当含水率为25%时出现速率弱化行为, 应力降增大。速率弱化样品的声发射数据以拉张微裂纹发育为主, 显微结构中出现大角度张性断裂带, 推测可能是水的化学弱化作用导致。实验结果可能对理解新丰江水库诱发地震提供新的认识: 低有效正应力下的速率弱化行为可能致使水库诱发地震, 而高含水率下的微弱速率弱化行为有利于慢滑移地震事件的产生。

关键词: 花岗岩断层泥, 速率弱化, 摩擦愈合, 声发射, 微裂纹发育, 水库诱发地震, 慢滑移

Abstract:

The Xinfengjiang Water Reservoir in Guangdong, China, is one of the reservoirs that has triggered earthquakes of magnitudes greater than 6. Numerous earthquakes have occurred since the reservoir's impoundment, making it one of the most active seismic zones in Guangdong. Disturbance in effective stress and water content in existing fault zones upon the water reservoir may play a critical role in induced earthquakes.

Here, we report 17 friction experiments performed on simulated granite fault gouges(28%quartz, 25% albite, and 44%microcline, particle size <0.25mm, 2mm thickness)collected from fault zones near Xinfengjiang Reservoir to investigate the effect of effective normal stress and water content. This was achieved using a direct shear apparatus associated with two acoustic emission(AE)sensors. Microstructure observation was also performed on post-deformed samples to discuss the possible mechanism of reservoir-induced earthquakes. Regarding the analysis method of acoustic emission data, we adopt a crack cumulative summation curve method, following the RA-AF crack classification method, which can successfully inverse and distinguish the possible different microcracking processes in deformed rock from the pure tensile microcrack development(k=1)to the pure shear microcrack development (k=-1) according to the variance of curve slope k value(i.e., -1~1). The velocity stepping(1-10-50~100μm/s)and slide-hold-slide(at a constant sliding velocity of 1 mm/s with hold intervals of 10-30-100-300-1 000-3 000 seconds)experiments were conducted at the fixed normal stresses of 0.5~20MPa(10%water content)effective normal stress and 0%~25%(10MPa effective normal stress)water content under drained conditions at room temperature. Acoustic emission signals were also recorded. The shear displacement of both types of experiments is~7mm.

(1)Velocity stepping experiments show that the wet samples with 10%water content exhibit a transition from velocity weakening to velocity strengthening at the normal stress of 10MPa, and the apparent dilatancy was observed for the samples showing velocity strengthening utilizing the changes in axial displacement during sliding. At the normal stress of 10MPa, the room dry sample also shows velocity strengthening accompanied by dilatancy. Still, the wet sample with 25%water content shows velocity weakening, though dilatancy was also observed. This may indicate the negative effect of water on velocity strengthening. In addition, AE analysis indicates the development of tensile microcracks(60%~80%)dominated for velocity weakening and the appearance of strongly developed shear microcracks dominated for velocity strengthening, which was consistent with the microstructural observation performed on the deformed samples. It clearly illustrates that the tensile fracture(T) zones developed in the samples showed velocity weakening, while the Ridel shear fracture(R) zones developed in the samples showed velocity strengthening.

(2)Slide-hold-slide experiments show a nonlinear relation between transient peak healing(Δμ_pk) and the logarithm of hold time(log(t_h)), or “non-Dieterich” healing behavior. By contrast, postpeak weakening(Δμ_w, a stress drop measured as the difference between the peak frictional strength and the steady-state friction of reshearing)shows a direct, near-linear relation with log(t_h). In general, Δμ_w increased with increasing log(t_h) and water content but reduced with increasing normal stress. This may indicate the lower normal stress, the higher water content and the longer hold time the more likely for the unsteady slip of the faults. AE analysis showed that the stress drop is positively correlated with the proportion of tensile cracks.

Based on the effects of the effective normal stress and water content on frictional properties, we suggest that the effect of hydrochemical weakening and increase of stress drop after healing may be the mechanisms responsible for a transition from velocity weakening to velocity weakening for granite gouges. The CNS model can well explain the “non-Dieterich” healing behavior of granite gouges. Combined with reservoir-induced earthquakes, it is indicated that the fault zone under Xinfengjiang Reservoir may have unstable slip below 5MPa effective normal stress and 25%water content, resulting in reservoir-induced earthquakes. Importantly, the weak rate weakening behavior under high water content is conducive to generating slow slip seismic events. The experimental results have certain indicative significance for reservoir-induced earthquakes.

Key words: Granite gouges, velocity weakening, frictional healing, acoustic emission, microcrack development, reservoir-induced earthquakes, slow slip

邵康, 刘金锋, 谢彬, 朱民杰. 正应力和含水率对花岗岩断层泥摩擦特性和声发射特征的影响[J]. 地震地质, 2024, 46(6): 1332-1356.

SHAO Kang, LIU Jin-feng, XIE Bin, ZHU Min-jie. FRICTIONAL PROPERTIES ASSOCIATED WITH ACOUSTIC EMISSION CHARACTERISTICS OF SIMULATED GRANITE FAULT GOUGES: EFFECTS OF NORMAL STRESS AND WATER CONTENT[J]. SEISMOLOGY AND GEOLOGY, 2024, 46(6): 1332-1356.

图/表 16

图1 摩擦本构定律示意图 a 速率阶跃示意图; b 摩擦愈合示意图(改自文献(Chen et al., 2015))

Fig. 1 Schematic diagram of friction constitutive law.

表1 花岗岩断层泥矿物成分的半定量分析

Table1 Semi-quantitative analysis of mineral composition in granite gouge

矿物种类	石英	钠长石	微斜长石	白云母	其他矿物
花岗岩断层泥/wt%	28	25	44	1	2

图2 直剪试验系统装样示意图

Fig. 2 Schematic diagram of the sample assembly used in direct shear experiments.

图3 VS-10MPa-10%实验中10~50μm/s速率阶跃阶段的最佳拟合结果

Fig. 3 The best fitting results for the VS-10MPa-10% experiment during the step phase at a rate of 10~50μm/s.

图4 a RA-AF裂纹分类方法示意图; b 裂纹分类参数累计曲线示意图(引自范财源等, 2023)

Fig. 4 Schematic diagram showing RA-AF crack classification(a) and Schematic diagram of crack cumulative summation curve showing inversed five types of microcrack developments with different k values(b) (indexed from FAN Cai-yuan et al., 2023).

图5 花岗岩断层泥(VS实验)的视摩擦系数、法向位移和剪切位移关系曲线 a 0.5~20MPa有效正应力(含水率为10%); b 0%~25%含水率(有效正应力为10MPa)。法向位移值增大表示压实, 减小表示剪胀

Fig. 5 The relationship curves of apparent friction coefficient, normal displacement, and shear displacement for granite gouge(VS experiment).

图6 花岗岩断层泥(SHS实验)的视摩擦系数、法向位移和剪切位移关系曲线 a 0.5~20MPa有效正应力(含水率为10%); b 0%~25%含水率(有效正应力为10MPa)

Fig. 6 The relationship curves of apparent friction coefficient, normal displacement, and shear displacement for granite fault gouge(Slide-Hold-Slide experiment).

表2 花岗岩断层泥摩擦本构参数汇总

Table2 Summary of friction constitutive parameters of granite gouge

有效正应力/MPa	含水率/%	$μ s s$ ^①	a-b^②	a	b	滑动模式
0.5	10	0.569	-4.58×10^-3	1.26×10^-3	5.84×10^-3	速率弱化,10μm/s准静态振荡
1	10	0.591	-4.20×10^-3	2.10×10^-3	6.30×10^-3	速率弱化,10μm/s准静态振荡
2	10	0.632	-3.52×10^-3	2.65×10^-3	6.17×10^-3	速率弱化
5	10	0.607	-1.68×10^-3	4.02×10^-3	5.70×10^-3	速率弱化
10	10	0.561	1.53×10^-3	3.94×10^-3	2.41×10^-3	速率强化
20	10	0.549	1.69×10^-3	4.37×10^-3	2.68×10^-3	速率强化
10	0	0.646	0.70×10^-3	4.59×10^-3	3.89×10^-3	速率强化
10	20	0.583	0.18×10^-3	4.97×10^-3	4.79×10^-3	速率强化
10	25	0.561	-0.52×10^-3	2.43×10^-3	2.95×10^-3	速率弱化

表2 花岗岩断层泥摩擦本构参数汇总

Table2 Summary of friction constitutive parameters of granite gouge

有效正应力/MPa	含水率/%	$μ s s$ ^①	a-b^②	a	b	滑动模式
0.5	10	0.569	-4.58×10^-3	1.26×10^-3	5.84×10^-3	速率弱化,10μm/s准静态振荡
1	10	0.591	-4.20×10^-3	2.10×10^-3	6.30×10^-3	速率弱化,10μm/s准静态振荡
2	10	0.632	-3.52×10^-3	2.65×10^-3	6.17×10^-3	速率弱化
5	10	0.607	-1.68×10^-3	4.02×10^-3	5.70×10^-3	速率弱化
10	10	0.561	1.53×10^-3	3.94×10^-3	2.41×10^-3	速率强化
20	10	0.549	1.69×10^-3	4.37×10^-3	2.68×10^-3	速率强化
10	0	0.646	0.70×10^-3	4.59×10^-3	3.89×10^-3	速率强化
10	20	0.583	0.18×10^-3	4.97×10^-3	4.79×10^-3	速率强化
10	25	0.561	-0.52×10^-3	2.43×10^-3	2.95×10^-3	速率弱化

图7 速率依赖性参数a-b随有效正应力和含水率的变化 a 0.5~20MPa有效正应力(含水率为10%); b 0%~25%含水率(有效正应力为10MPa)。平均值的定义见表2中的表注②

Fig. 7 The variation of the rate-dependent parameter a-b with effective normal stress and water content.

表3 花岗岩断层泥摩擦愈合参数汇总

Table3 Summary of frictional healing parameters of granite gouge

有效正应力/MPa	含水率/%	$μ s s$ ^①	保持时间阈值^②/s	$β 1$ ^③	$β 2$ ^④	$β 3$ ^⑤
0.5	10	0.576	1000	0.019	0.063	0.022
1	10	0.621	1000	0.015	0.034	0.012
5	10	0.621	1000	0.011	0.036	0.009
10	10	0.604	300	0.0063	0.017	0.0055
20	10	0.607	300	0.0054	0.016	0.0049
10	0	0.665	1000	0.0067	0.0024	0.0061
10	20	0.595	300	0.0078	0.018	0.0059
10	25	0.584	300	0.0073	0.019	0.0077

表3 花岗岩断层泥摩擦愈合参数汇总

Table3 Summary of frictional healing parameters of granite gouge

有效正应力/MPa	含水率/%	$μ s s$ ^①	保持时间阈值^②/s	$β 1$ ^③	$β 2$ ^④	$β 3$ ^⑤
0.5	10	0.576	1000	0.019	0.063	0.022
1	10	0.621	1000	0.015	0.034	0.012
5	10	0.621	1000	0.011	0.036	0.009
10	10	0.604	300	0.0063	0.017	0.0055
20	10	0.607	300	0.0054	0.016	0.0049
10	0	0.665	1000	0.0067	0.0024	0.0061
10	20	0.595	300	0.0078	0.018	0.0059
10	25	0.584	300	0.0073	0.019	0.0077

图8 摩擦愈合参数 Δ μ p 、 Δ μ w 随保持时间的变化 a 0.5~20MPa有效正应力(含水率为10%); b 0%~25%含水率(有效正应力为10MPa)。空心点代表数据拟合程度一般

Fig. 8 The variations of the friction healing parameters Δμp and Δμw with holding time.

图9 花岗岩断层泥在VS实验下的声发射微裂纹信号计算结果 a、 b 2MPa-10%样品的累计裂纹信号对法向位移的响应及裂纹分类参数累计曲线; c、 d 20MPa-10%样品的累计裂纹信号对法向位移的响应及裂纹分类参数累计曲线

Fig. 9 Calculation of microcrack signals for granite gouge in velocity stepping experiments.

图10 花岗岩断层泥在10MPa有效应力下的裂纹分类参数累计曲线

Fig. 10 Crack cumulative summation curve of granite gouge at effective normal stress of 10MPa. a VS-10MPa-20%; b VS-10MPa-25%; c SHS-10MPa-20%; d SHS-10MPa-25%

图11 变形样品的光学显微结构

Fig. 11 Fabrics of granite gouge after shear deformation as seen in OM image. a VS-1MPa-10%; b VS-2MPa-10%; c VS-10MPa-10%; d VS-20MPa-10%

图12 VS-2MPa-10%下变形样品的扫描电镜显微结构

Fig. 12 Fabrics of granite gouge at 2MPa effective normal stress and 10%water content after velocity stepping experiment as seen in SEM image.

图13 摩擦愈合参数 Δ μ r 随保持时间的变化 a 0.5~20MPa有效正应力(含水率为10%); b 0%~25%含水率(有效正应力为10MPa)

Fig. 13 Frictional healing parameters Δ μ r plotted as functions of the logarithm of hold time.

参考文献 62

[1]	陈四利, 冯夏庭, 李邵军. 2003. 岩石单轴抗压强度与破裂特征的化学腐蚀效应[J]. 岩石力学与工程学报, 22(4): 547—551.
	CHEN Si-li, FENG Xia-ting, LI Shao-jun. 2003. Effects of chemical erosion on uniaxial compressive strength and meso-fracturing behaviors of rock[J]. Chinese Journal of Rock Mechanics and Engineering, 22(4): 547—551(in Chinese).
[2]	储超群, 吴顺川, 曹振生, 等. 2021. 基于声发射技术的花岗岩破裂特征试验研究[J]. 中南大学学报(自然科学版), 52(8): 2919—2932.
	CHU Chao-qun, WU Shun-chuan, CAO Zhen-sheng, et al. 2021. Experimental research on fracture characteristics of granite with acoustic emission technology[J]. Journal of Central South University(Science and Technology), 52(8): 2919—2932(in Chinese).
[3]	邓朝福, 刘建锋, 陈亮, 等. 2017. 不同含水状态花岗岩断裂力学行为及声发射特征[J]. 岩土工程学报, 39(8): 1538—1544.
	DENG Chao-fu, LIU Jian-feng, CHEN Liang, et al. 2017. Mechanical behaviors and acoustic emission characteristics of fracture of granite under different moisture conditions[J]. Chinese Journal of Geotechnical Engineering, 39(8): 1538—1544(in Chinese).
[4]	丁原章, 潘建雄, 肖安予, 等. 1983. 新丰江水库诱发地震的构造条件[J]. 地震地质, 5(3): 63—74.
	DING Yuan-zhang, PAN Jian-xiong, XIAO An-yu, et al. 1983. Tectonic environment of reservoir induced earthquake in the Xinfengjiang reservoir area[J]. Seismology and Geology, 5(3): 63—74(in Chinese).
[5]	窦子豪, 赵志宏, 高天阳, 等. 2021. 水岩作用下花岗岩裂隙剪切力学特性演化规律[J]. 清华大学学报(自然科学版), 61(8): 792—798.
	DOU Zi-hao, ZHAO Zhi-hong, GAO Tian-yang, et al. 2021. Evolution law of water-rock interaction on the shear behavior of granite fractures[J]. Journal of Tsinghua University(Science and Technology), 61(8): 792—798(in Chinese).
[6]	范财源, 孟范宝, 刘金锋. 2023. 单轴压缩作用下岩石脆性破裂机制的声发射识别[J]. 中山大学学报(自然科学版), 62(3): 14—24.
	FAN Cai-yuan, MENG Fan-bao, LIU Jin-feng. 2023. Characterization of brittle failure modes of rock under uniaxial compression using acoustic emission[J]. Acta Scientiarum Naturalium Universitatis Sunyatseni, 62(3): 14—24(in Chinese).
[7]	龚钢延, 谢原定. 1991. 新丰江水库地震区内孔隙流体扩散与原地水力扩散率的研究[J]. 地震学报, 13(3): 364—371.
	GONG Gang-yan, XIE Yuan-ding. 1991. Research on the diffusion of pore fluid and in-situ hydraulic diffusivity in the epicentral region of Xinfengjiang reservoir earthquakes[J]. Acta Seismologica Sinica, 13(3): 364—371(in Chinese).
[8]	郭春清, 沈忠民, 张林晔, 等. 2003. 砂岩储层中有机酸对主要矿物的溶蚀作用及机理研究综述[J]. 地质地球化学, 31(3): 53—57.
	GUO Chun-qing, SHEN Zhong-min, ZHANG Lin-ye, et al. 2003. The corrosion and its mechanism of organic acids on main minerals in oil-gas reservoir sand rocks[J]. Geology-Geochemistry, 31(3): 53—57(in Chinese).
[9]	郭贵安, 刘特培, 秦乃岗, 等. 2004. 新丰江水库1961—1999年小震综合机制解结果分析[J]. 地震学报, 26(3): 261—268.
	GUO Gui-an, LIU Te-pei, QIN Nai-gang, et al. 2004. Analysis on small-earthquake composite fault plane solutions from 1961 to 1999 in Xinfengjiang reservoir area[J]. Acta Seismologica Sinica, 26(3): 261—268(in Chinese).
[10]	胡毓良, 陈献程. 1979. 我国的水库地震及有关成因问题的讨论[J]. 地震地质, 1(4): 45—57.
	HU Yu-liang, CHEN Xian-cheng. 1979. Discussion on the reservoir-induced earthquakes in China and some problems related to their origin[J]. Seismology and Geology, 1(4): 45—57(in Chinese).
[11]	雷蕙如, 周永胜, 姚文明, 等. 2022. 安宁河断层地震成核条件研究: 来自天然花岗岩断层泥摩擦实验的启示[J]. 地球物理学报, 65(3): 978—991.
	LEI Hui-ru, ZHOU Yong-sheng, YAO Wen-ming, et al. 2022. Earthquake nucleation conditions of Anninghe Fault: Constrains from frictional experiments on natural granite gouge[J]. Chinese Journal of Geophysics, 65(3): 978—991(in Chinese).
[12]	李铀, 朱维申, 白世伟, 等. 2003. 风干与饱水状态下花岗岩单轴流变特性试验研究[J]. 岩石力学与工程学报, 22(10): 1673—1677.
	LI You, ZHU Wei-shen, BAI Shi-wei, et al. 2003. Uniaxial experimental study on rheological properties of granite in air-dried and saturated states[J]. Chinese Journal of Rock Mechanics and Engineering, 22(10): 1673—1677(in Chinese).
[13]	刘洋, 何昌荣. 2020. 普通角闪石的速率依赖性及其对俯冲带慢滑移机制的启示[J]. 地震地质, 42(6): 1267—1281. doi:10.3969/j.issn.0253-4967.2020.06.001.
	LIU Yang, HE Chang-rong. 2020. Rate dependence of friction of hornblende and implications for unstable slips[J]. Seismology and Geology, 42(6): 1267—1281(in Chinese). DOI
[14]	任凤文, 何昌荣. 2014. 热水条件下花岗质糜棱岩的摩擦滑动实验研究[J]. 地球物理学报, 57(3): 877—883.
	REN Feng-wen, HE Chang-rong. 2014. An experimental study of frictional sliding of granite mylonite under hydrothermal conditions[J]. Chinese Journal of Geophysics, 57(3): 877—883(in Chinese).
[15]	沈崇刚, 陈厚群, 张楚汉, 等. 1974. 新丰江水库地震及其对大坝的影响[J]. 中国科学, 4(2): 184—205.
	SHEN Chong-gang, CHEN Hou-qun, ZHANG Chu-han, et al. 1974. Xinfengjiang reservoir earthquakes and its influence on the dam[J]. Scientia Sinica, 4(2): 184—205(in Chinese).
[16]	申林方, 冯夏庭, 潘鹏志, 等. 2010. 单裂隙花岗岩在应力-渗流-化学耦合作用下的试验研究[J]. 岩石力学与工程学报, 29(7): 1379—1388.
	SHEN Lin-fang, FENG Xia-ting, PAN Peng-zhi, et al. 2010. Experimental research on mechano-hydro-chemical coupling of granite with single fracture[J]. Chinese Journal of Rock Mechanics and Engineering, 29(7): 1379—1388(in Chinese).
[17]	谭文彬, 何昌荣. 2008. 高温高压及干燥条件下斜长石和辉石断层泥的摩擦滑动研究[J]. 地学前缘, 15(3): 279—286.
	TAN Wen-bin, HE Chang-rong. 2008. Frictional sliding of pyroxene and plagioclase gouges in gabbro under elevated temperature and dry condition[J]. Earth Science Frontiers, 15(3): 279—286(in Chinese).
[18]	于雯泉, 陈勇, 杨立干, 等. 2014. 酸性环境致密砂岩储层石英的溶蚀作用[J]. 石油学报, 35(2): 286—293. DOI
	YU Wen-quan, CHEN Yong, YANG Li-gan, et al. 2014. Dissolution of quartz in tight sandstone reservoirs in an acidic environment[J]. Acta Petrolei Sinica, 35(2): 286—293(in Chinese). DOI
[19]	张虎男, 吴堑红. 1994. 华南沿海主要活动断裂带的比较构造研究[J]. 地震地质, 16(1): 43—52.
	ZHANG Hu-nan, WU Qian-hong. 1994. A comparative study of main active fault zones along the coast of South China[J]. Seismology and Geology, 16(1): 43—52(in Chinese).
[20]	周永胜. 2019. 基岩区断层黏滑与蠕滑的地质标志和岩石力学实验证据[J]. 地震地质, 41(5): 1266—1272. doi: 10.3969/j.issn.0253-4967.2019.05.013.
	ZHOU Yong-sheng. 2019. The geological and rock mechanical distinction evidence between stick-slip and creep in host rock segments of fault[J]. Seismology and Geology, 41(5): 1266—1272(in Chinese). DOI
[21]	Aggelis D G. 2011. Classification of cracking mode in concrete by acoustic emission parameters[J]. Mechanics Research Communications, 38(3): 153—157. https://doi.org/10.1016/j.mechrescom.2011.03.007.
[22]	Ampuero J, Rubin A M. 2008. Earthquake nucleation on rate and state faults: Aging and slip laws[J]. Journal of Geophysical Research: Solid Earth, 113(B1): B01302. https://doi.org/10.1029/2007JB005082.
[23]	Araki E, Saffer D M, Kopf A J, et al. 2017. Recurring and triggered slow-slip events near the trench at the Nankai Trough subduction megathrust[J]. Science, 356(6343): 1157—1160. doi: 10.1126/science.aan3120. PMID
[24]	Bedford J D, Faulkner D R, Allen M J, et al. 2021. The stabilizing effect of high pore-fluid pressure along subduction megathrust faults: Evidence from friction experiments on accretionary sediments from the Nankai Trough[J]. Earth and Planetary Science Letters, 574:117161. https://doi.org/10.1016/j.epsl.2021.117161.
[25]	Beeler N M, Tullis T E, Blanpied M L, et al. 1996. Frictional behavior of large displacement experimental faults[J]. Journal of Geophysical Research, 101(B4): 8697—8715. https://doi.org/10.1029/96JB00411.
[26]	Blanpied M L, Lockner D A, Byerlee J D. 1991. Fault stability inferred from granite sliding experiments at hydrothermal conditions[J]. Geophysical Research Letters, 18(4): 609—612. https://doi.org/10.1029/91GL00469.
[27]	Blanpied M L, Lockner D A, Byerlee J D. 1995. Frictional slip of granite at hydrothermal conditions[J]. Journal of Geophysical Research: Solid Earth, 100(B7): 13045—13064. https://doi.org/10.1029/95JB00862.
[28]	Blanpied M L, Marone C J, Lockner D A, et al. 1998. Quantitative measure of the variation in fault rheology due to fluid-rock interactions[J]. Journal of Geophysical Research, 103(B5): 9691—9712. https://doi.org/10.1029/98JB00162.
[29]	Blanpied M L, Tullis T E, Weeks J D. 1987. Frictional behavior of granite at low and high sliding velocities[J]. Geophysical Research Letters, 14(5): 554—557. https://doi.org/10.1029/GL014i005p00554.
[30]	Chen J Y, Spiers C J. 2016. Rate and state frictional and healing behavior of carbonate fault gouge explained using microphysical model[J]. Journal of Geophysical Research: Solid Earth, 121(12): 8642—8665. https://doi.org/10.1002/2016JB013470.
[31]	Chen J Y, Verberne B A, Spiers C J. 2015. Effects of healing on the seismogenic potential of carbonate fault rocks: Experiments on samples from the Longmenshan Fault, Sichuan, China[J]. Journal of Geophysical Research: Solid Earth, 120(8): 5479—5506. https://doi.org/10.1002/2015JB012051.
[32]	Deichmann N, Giardini D. 2009. Earthquakes induced by the stimulation of an enhanced geothermal system below Basel(Switzerland)[J]. Seismological Research Letters, 80(5): 784—798. https://doi.org/10.1785/gssrl.80.5.784.
[33]	Delorey A A, van der Elst N J, Johnson P A. 2017. Tidal triggering of earthquakes suggests poroelastic behavior on the San Andreas Fault[J]. Earth and Planetary Science Letters, 460:164—170. https://doi.org/10.1016/j.epsl.2016.12.014.
[34]	Den Hartog S A M, Spiers C J. 2013. Influence of subduction zone conditions and gouge composition on frictional slip stability of megathrust faults[J]. Tectonophysics, 600:75—90. https://doi.org/10.1016/j.tecto.2012.11.006.
[35]	Di Toro G, Goldsby D L, Tullis T E. 2004. Friction falls towards zero in quartz rock as slip velocity approaches seismic rates[J]. Nature, 427: 436—439.
[36]	Di Toro G, Han R, Hirose T, et al. 2011. Fault lubrication during earthquake[J]. Nature, 471: 494—498.
[37]	Dieterich J H. 1978. Time-dependent friction and the mechanics of stick slip[J]. Pure and Applied Geophysics, 116: 790—806.
[38]	Dieterich J H. 1979. Modeling of rock friction: 1. Experimental results and constitutive equations[J]. Journal of Geophysical Research: Solid Earth, 84(B5): 2161—2168. https://doi.org/10.1029/JB084iB05p02161.
[39]	Dong L J, Chen Y C, Sun D Y, et al. 2021. Implications for rock instability precursors and principal stress direction from rock acoustic experiments[J]. International Journal of Mining Science and Technology, 31(5): 789—798. https://doi.org/10.1016/j.ijmst.2021.06.006.
[40]	Ellsworth W L. 2013. Injection-induced earthquakes[J]. Science, 341(6142): 142. doi: 10.1126/science.1225942.
[41]	Gupta H K. 2002. A review of recent studies of triggered earthquakes by artificial water reservoirs with special emphasis on earthquakes in Koyna, India[J]. Earth-Science Reviews, 58(3-4): 279—310. https://doi.org/10.1016/S0012-8252(02)00063—6.
[42]	He L P, Sun X L, Yang H F, et al. 2018. Upper crustal structure and earthquake mechanism in the Xinfengjiang Water Reservoir, Guangdong, China[J]. Journal of Geophysical Research: Solid Earth, 123(5): 3799—3813. https://doi.org/10.1029/2017JB015404.
[43]	Johnson K M, Shelly D R, Bradley A M. 2013. Simulations of tremor-related creep reveal a weak crustal root of the San Andreas Fault[J]. Geophysical Research Letters, 40(7): 1300—1305. https://doi.org/10.1002/grl.50216.
[44]	Keranen K M, Savage H M, Abers G A, et al. 2013. Potentially induced earthquakes in Oklahoma, USA: Links between wastewater injection and the 2011 M_W5.7 earthquake sequence[J]. Geology, 41(6): 699—702. https://doi.org/10.1130/G34045.1.
[45]	Liu J F, Hunfeld L B, Niemeijer A R, et al. 2020. Frictional properties of simulated shale-coal fault gouges: Implications for induced seismicity in source rocks below Europe's largest gas field[J]. International Journal of Coal Geology, 226:103499. https://doi.org/10.1016/j.coal.2020.103499.
[46]	Liu Y, Rice J R. 2009. Slow slip predictions based on granite and gabbro friction data compared to GPS measurements in northern Cascadia[J]. Journal of Geophysical Research: Solid Earth, 114(B9): B09407. https://doi.org/10.1029/2008JB006142.
[47]	Logan J M, Friedman M, Higgs N, et al. 1979. Analysis of Actual Fault Zones in Bedrock[M]. United States Geological Survey(USGS)Publications Warehouse:305—343.
[48]	Mair K, Marone C. 1999. Friction of simulated fault gouge for a wide range of velocities and normal stresses[J]. Journal of Geophysical Research, 104(B12): 28899—28914. https://doi.org/10.1029/1999JB900279.
[49]	Marone C. 1998. Laboratory-derived friction laws and their application to seismic faulting[J]. Annual Review of Earth and Planetary Sciences, 26(1): 643—696. https://doi.org/10.1146/annurev.earth.26.1.643.
[50]	Marone C, Raleigh C B, Scholz C H. 1990. Frictional behavior and constitutive modeling of simulated fault gouge[J]. Journal of Geophysical Research: Solid Earth, 95(B5): 7007—7025. https://doi.org/10.1029/JB095iB05p07007.
[51]	Meng F B, Ge H K, Yan W, et al. 2016. Effect of saturated fluid on the failure mode of brittle gas shale[J]. Journal of Natural Gas Science and Engineering, 35(6): 624—636. https://doi.org/10.1016/j.jngse.2016.09.008.
[52]	Ohno K, Ohtsu M. 2010. Crack classification in concrete based on acoustic emission[J]. Construction and Building Materials, 24(12): 2339—2346. https://doi.org/10.1016/j.conbuildmat.2010.05.004.
[53]	Proctor B, Lockner D A, Kilgore B D, et al. 2020. Direct evidence for fluid pressure, dilatancy, and compaction affecting slip in isolated faults[J]. Geophysical Research Letters, 47(16): e2019GL086767. https://doi.org/10.1029/2019GL086767.
[54]	Ruina A L. 1983. Slip instability and state variable friction laws[J]. Journal of Geophysical Research, 88(B12): 10359—10370. https://doi.org/10.1029/JB088iB12p10359.
[55]	Scholz C H. 1987. Wear and gouge formation in brittle faulting[J]. Geology, 15(6): 493—495. https://doi.org/10.1130/0091-7613(1987)15<493:WAGFIB>2.0.CO; 2.
[56]	Scuderi M M, Carpenter B M, Marone C. 2014. Physicochemical processes of frictional healing: Effects of water on stick-slip stress drop and friction of granular fault gouge[J]. Journal of Geophysical Research: Solid Earth, 119(5): 4090—4105. https://doi.org/10.1002/2013JB010641.
[57]	Scuderi M M, Collettini C, Viti E, et al. 2017. Evolution of shear fabric in granular fault gouge from stable sliding to stick slip and implications for fault slip mode[J]. Geology, 45(8): 731—734. https://doi.org/10.1130/G39033.1.
[58]	Segall P, Fitzgerald S D. 1998. A note on induced stress changes in hydrocarbon and geothermal reservoirs[J]. Tectonophysics, 289(1-3): 117—128. https://doi.org/10.1016/S0040-1951(97)00311-9.
[59]	Stein R S. 1999. The role of stress transfer in earthquake occurrence[J]. Nature, 402(6762): 605—609.
[60]	Tesei T, Collettini C, Carpenter B M, et al. 2012. Frictional strength and healing behavior of phyllosilicate-rich faults[J]. Journal of Geophysical Research: Solid Earth, 117(B9): B09402. https://doi.org/10.1029/2012JB009204.
[61]	Yao L, Ma S L. 2013. Experimental simulation of coseismic fault sliding: Significance, technological methods and research progress of high-velocity frictional experiment[J]. Progress in Geophysics, 28(2): 607—623. https://doi:10.6038/pg20130210.
[62]	Zang A, Oye V, Jousset P, et al. 2014. Analysis of induced seismicity in geothermal reservoirs: An overview[J]. Geothermics, 52: 6—21.