远场差异构造应力作用下包体-地层地应力分析  

Analysis of in-situ stress distribution of inclusion-stratum system under far-field differential tectonic stress

作　　者：周龙寿 胡才博[1] 蔡永恩 张怀[1] ZHOU Long-shou;HU Cai-bo;CAI Yong-en;ZHANG Huai(School of earth and Planetary Sciences,University of Chinese Academy of Sciences,Key Laboratory of Computational Geodynamics,Chinese Academy of Sciences,Beijing 100049,China;Institute of Crustal Dynamacis,China Earthquake Administration,Beijing 100085,China;Department of Geophysics,Peking University,Beijing 100871,China)

机构地区：[1]中国科学院大学地球与行星科学学院,中国科学院计算地球动力学重点实验室,北京100049 [2]中国地震局地壳应力研究所,北京100085 [3]北京大学地球物理学系,北京100871

出　　处：《地球物理学进展》2020年第2期519-529,共11页Progress in Geophysics

基　　金：国家重点研发项目“华北克拉通成矿系统的深部过程与成矿机理”子课题(2016YFC0600101);国家重点研发项目“地球系统模式的改进、应用开发和高性能计算”子课题(2016YFB0200801);国家自然科学基金面上项目(41474085);中国地震局地壳应力研究所中央级公益性科研院所基本科研业务专项(ZDJ2015-14)联合资助.

摘　　要：地应力场的不均匀分布是地球科学非常关心的问题,远场差异构造应力及介质本身的不均匀性对地应力场的不均匀分布都有重要影响.本文利用弹性力学理论,以地球科学的包体-地层系统为例,推导了边界差异构造应力条件下包体-地层系统位移场和应力场的解析表达式.将远场差异构造应力分解为均匀构造应力和偏构造应力两部分,通过边值问题的一般求解方法,分别得出了这两种情况下的理论解.通过将两部分理论解叠加,得到了边界差异构造应力条件下包体-地层系统的位移场、应力场和连接载荷.通过推导的解析解与有限元数值解进行比较,两者非常一致.通过分析包体-地层系统、材料参数、几何尺寸、远场构造应力的大小和方向等因素对包体-地层位移场和应力场分布的影响,可以用于探讨钻孔应变等包体应力(应变)计观测的地震应变阶、慢地震、地震孕育、火山喷发、地球自由振荡、地震波等现象的地球动力学机制.结果表明,远场地应力的分布主要受控于边界构造应力的大小和方向.在包体内部,应力场基本是均匀分布的;而在包体附近,由于介质差异,地应力场的不均匀性非常显著,并且有一定的优势方向,对地应力集中部位的分析为钻孔应变观测等地球动力学研究手段提供了基础理论参考.The non-uniform distribution of in-situ stress field is a very important subject in geoscience. The far-field differential tectonic stress and the inhomogeneity of the medium itself have important effects on the non-uniform distribution of in-situ stress field. Based on the theory of elasticity and taking an inclusion-stratum system of geoscience as an example, the analytical expressions of displacement field and stress field of inclusion-stratum system under boundary differential tectonic stress are derived in this paper. The far-field differential tectonic stress is decomposed into two parts: uniform tectonic stress and partial tectonic stress. The theoretical solutions of these two cases are obtained by the general solution method of boundary value problem. The displacement field, stress field and connecting load of inclusion-stratum system under boundary differential tectonic stress are obtained by superposition of results of two cases. We compare the deduced analytical solution with the corresponding finite element numerical solution. They are very consistent with each other. By analyzing the influence of inclusion-stratum system, material parameters, geometric size, magnitude and direction of far-field tectonic stress on the displacement field and stress field distribution of inclusion-formation, it can be used to discuss the geodynamic phenomena such as seismic strain order, slow earthquake, earthquake gestation, volcanic eruption, free earth oscillation and seismic wave observed by inclusion stress(strain) gauge such as borehole strain. The results show that the distribution of in-situ stress in far field is mainly controlled by the magnitude and direction of boundary tectonic stress. In the inclusion, the stress field is uniformly distributed. In the vicinity of inclusion, the inhomogeneity of in-situ stress field is very significant and it has a certain advantage direction due to the difference of medium. The analysis of the location of in-situ stress concentration provides basic theoretical reference f

关 键 词：地应力 包体-地层系统 解析解 数值解 

分 类 号：P313[天文地球—固体地球物理学]