摘要
随着离散元理论和计算机技术的发展,离散元方法已经广泛应用到不同尺度的构造模拟中。相较于传统的沙箱模拟实验,离散元可以更精确地控制实验的边界条件,定量的分析构造变形过程,有助于从细观尺度深入认识地层力学性质对构造变形过程的影响。本文系统阐述了基于离散元的构造变形定量分析方法,结合一个典型的挤压构造离散元数值模拟实验,模拟了水平挤压环境下构造的形成过程,并对变形过程中的应力、应变分布变化与裂缝生成规律进行分析,取得以下认识:(1)该模拟实验的构造以前展式的逆冲叠瓦断层为主,断层从挤压端到远离挤压端依次活动;(2)裂缝与断层形成有密切关系,局部区域内聚集的大量裂缝是产生断层的诱因;(3)断层形成初期,断层内物质运动距离较小,产生裂缝增量最多;断层活动后期,裂缝增量减少;(4)体积应变可以表征裂缝类型(拉张或压缩),变形应变可以区分正向和反向逆冲断层;(5)平均应力大小与地形起伏呈正相关关系,最大剪切应力持续在将要形成的新断层处累积,直至该新断层形成,最大剪切应力继而消散,继续往前传播,在下一个将要形成的新断层处累积。研究结果表明离散元方法在构造变形、应力应变与裂缝预测定量研究中具有巨大潜力。
With development of discrete element theory and computer technology, the discrete element method has been widely used in structural simulation at different scales. Compared with the traditional scaled analog(sandbox) experiments,the discrete element numerical simulation can precisely control the experimental boundary conditions and quantitatively analyze structural deformation process, which is helpful for deeply understanding the mechanical properties and deformation mechanism of stratum from the mesoscopic scale. In this paper, based on a typical discrete element simulation of compressive tectonics, we systematically expounded the tectonic deformation quantitative analysis method,highlighted the superiority of tectonic deformation in mesoscale, and obtained the following results:(1) In the typical numerical simulation of compressive tectonics, the forward spreading thrust imbricated faults are dominant, and the faults generate in sequence from the compression end to those far from the compression end.(2) Fractures are closely related to the formation of faults, the interval in which the fracture generation reaches its peak precedes the one in which the fault appears the most active.(3) In the early stage of fault formation, the faults have a small displacement. However,the number of new fractures is the largest in this stage. In the later stage of fault activity, the fault-slip extension amount increases linearly with the shrinkage of the model, and the number of new fractures is less.(4) Volumetric strain can represent fracture types(tension or compression), and deformation strain can distinguish forward and back thrust faults.(5) The average stress is positively correlated with topographic relief, and the maximum shear stress continues to accumulate under the new fault to be formed until the new fault is formed, then the shear stress begins to dissipate and spread forward, accumulating at the next new fault to be formed. The results of this study show that the discrete element method has great potential in the quantitative research of structural deformation, stress-strain, and fracture prediction.
作者
李长圣
尹宏伟
徐雯峤
吴珍云
管树巍
贾东
任荣
LI Changsheng;YIN Hongwei;XU Wenqiao;WU Zhenyun;GUAN Shuwei;JIA Dong;REN Rong(State Key Laboratory of Nuclear Resources and Environment,Nanchang 330013,Jiangxi,China;School of Earth Sciences,East China University of Technology,Nanchang 330013,Jiangxi,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing 210023,Jiangsu,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)
出处
《大地构造与成矿学》
EI
CAS
CSCD
北大核心
2022年第4期645-661,共17页
Geotectonica et Metallogenia
基金
国家自然科学基金项目(42102270、41972219、42172232、41927802、41572187、41602208)
东华理工大学博士启动基金项目(DHBK2019024、DHBK2019053)
中国石油天然气股份有限公司项目(2018A-0101)联合资助。
关键词
离散元
构造变形
挤压构造
应力应变
定量分析
discrete element method
structural deformation
compressive tectonics
stress and strain
quantitative analysis
