地震触发下砂岩侵入体变形模拟实验研究  

Experimental Study of Deformation Mechanisms of Earthquaketriggered Sand Injectites

作　　者：刘作松 易雪斐[1,2] 吉霞 向建波 LIU ZuoSong;YI XueFei;JI Xia;XIANG JianBo(School of Geosciences,Yangtze University,Wuhan 430100,China;Key Laboratory of Exploration Technologies for Oil and Gas Resources(Yangtze University),Ministry of Education,Wuhan 430100,China)

机构地区：[1]长江大学地球科学学院,武汉430100 [2]长江大学“油气资源与勘探技术”教育部重点实验室,武汉430100

出　　处：《沉积学报》2023年第5期1530-1542,共13页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42130813,41702116)。

摘　　要：砂岩侵入体形成的触发机制有差异压实、地震、流体注入、波浪、重力滑动等,但普遍认为地震是最常见的一种触发机制。目前对于地震触发的砂岩侵入体的变形机理研究还相对薄弱,通过建立一套模拟地震触发砂岩侵入体的实验装置,成功地模拟了地震发生不同阶段的砂质变化过程。基于实验结果观察、分析,将地震触发砂岩侵入体的形成过程分为三个演化阶段,即:(1)震前阶段,局部地层因差异压实或地层饱含流体,导致砂质地层微弱起伏变形或无变化;(2)震中阶段,由于地震循环剪切波的影响以及不同介质内地震波波速存在差异,地层异常压力迅速增大并突破上覆盖层破裂强度,产生裂缝,同时砂质发生液化、流化形成一系列的变形构造;(3)震后阶段,伴随余震的产生,液化砂质会继续进行小规模的迁移改动直到地震完全结束,砂岩侵入体整体形态固定。地震作用可以独立触发砂岩侵入,也可以诱发其他地质作用,共同控制砂岩侵入体的形成。The mechanisms of the formation of sand injectites include differential compaction,earthquakes,fluid in⁃jection,waves and gravitational landslides,etc.Of these,earthquakes are generally considered to be the most com⁃mon mechanism.At present,relatively few studies of the mechanism for earthquake-triggered sand injectites have been reported.The process at different earthquake stages was simulated in this study using a purpose-designed and built experimental device for simulating the production of earthquake-triggered sand injectites.Based on observation and analysis of the experimental results,three evolution stages in the formation process of earthquake-triggered sand injectites are identified.(1)Prior to an earthquake,local differential compaction or fluid-saturated strata may pro⁃duce slight undulations of sandy strata,or there may be no change some cases.(2)The epicenter stage,in which dif⁃ferent media transmit the seismic waves at different velocities and cause rapid rises in abnormal pressures within the formation,causing simultaneous fracturing and liquefaction of the sand if the rupture strength of the overlying layers is exceeded.(3)The post-earthquake stage in which,as well as continuing aftershocks,abnormal pressures are re⁃tained in the formation.Liquefied sand continues to deform and migrate until the earthquake activity ceases complete⁃ly,and the final shape of the sand injectites is evident.Earthquakes may also cause sandstone intrusion and induce other geological processes,all of which may contribute to the formation of sand injectites.

关 键 词：地震 砂岩侵入体 物理模拟 形成机理 

分 类 号：P512.2[天文地球—地质学]