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Naigen Tan, Renshu Yang, and Zhuoying Tan, Influence of complicated faults on the differentiation and accumulation of in-situ stress in deep rock mass, Int. J. Miner. Metall. Mater., 30(2023), No. 5, pp.791-801. https://dx.doi.org/10.1007/s12613-022-2528-y
Naigen Tan, Renshu Yang, and Zhuoying Tan, Influence of complicated faults on the differentiation and accumulation of in-situ stress in deep rock mass, Int. J. Miner. Metall. Mater., 30(2023), No. 5, pp.791-801. https://dx.doi.org/10.1007/s12613-022-2528-y
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复杂断层对深部岩体原位应力分异与集中的影响

摘要: 地应力随深度呈线性增长,在深部高应力将成为常态。随着深度的增大地质结构复杂性增加。断层、小裂缝、节理裂隙广泛发育。为了探索断层对地应力的影响及其发生机制,本文在7个超千米钻孔中进行了水压致裂地应力测试,定量确定了断层上下盘、断层间、断层端部、断层交汇处及断层远场的应力。研究了断层位置和属性对应力大小和方向的影响。通过三维数值模拟,阐明了断层附近应力的非均质性,解释了断层对地应力积聚和分异的影响。受区域构造及断层作用影响,地应力大小、方向以及状态在不同位置发生显著的分异。在断层附近,地应力的集中程度和方向变化随断层位置而发生差异;在离断层较远处,地应力大小和方向与区域构造应力一致。利用历史地震动矢量对震源机制解进行了验证。结果表明,断层属性和位置将对应力分异产生显著影响。应力分异由强到弱依次为断层间、断层交汇处、下盘、断层端部及上盘,而方向变化强弱依次为下盘、断层间、断层端部、断层交汇处和上盘,揭示了断层诱发应力累积和方向转变的内在机制。

 

Influence of complicated faults on the differentiation and accumulation of in-situ stress in deep rock mass

Abstract: High geostress will become a normality in the deep because in-situ stress rises linearly with depth. The geological structure grows immensely intricate as depth increases. Faults, small fractures, and joint fissures are widely developed. The objective of this paper is to identify geostress anomalies at a variety of locations near faults and to demonstrate their accumulation mechanism. Hydrofracturing tests were conducted in seven deep boreholes. We conducted a test at a drilling depth of over one thousand meters to reveal and quantify the influence of faults on in-situ stresses at the hanging wall, footwall, between faults, end of faults, junction of faults, and far-field of faults. The effect of fault sites and characteristics on the direction and magnitude of stresses has been investigated and compared to test boreholes. The accumulation heterogeneity of stresses near faults was illustrated by a three-dimensional numerical simulation, which is utilized to explain the effect of faults on the accumulation and differentiation of in-situ stress. Due to regional tectonics and faulting, the magnitude, direction, and stress regime are all extremely different. The concentration degree of geostress and direction change will vary with the location of faults near faults, but the magnitude and direction of in-situ stress conform to regional tectonic stress at a distance from the faults. The focal mechanism solution has been verified using historical seismic ground motion vectors. The results demonstrate that the degree of stress differentiation varies according to the fault attribute and its position. Changes in stress differentiation and its ratio from strong to weak occur between faults, intersection, footwall, end of faults, and hanging wall; along with the sequence of orientation is the footwall, between faults, the end of faults, intersection, and hanging wall. This work sheds new light on the fault-induced stress accumulation and orientation shift mechanisms across the entire cycle.

 

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