Three-dimensional numerical simulation of rupture process of overlying soil caused by buried normal fault movement
-
摘要: 通过建立三维数值模型,对隐伏正断层在均匀错动和倾斜错动方式下土体的破裂过程进行研究。利用应力罗德参数和等效塑性应变分别对断层错动过程中上覆土体的应力状态和破坏形式进行分析,并提出土体破裂的判别方法。通过对数值模拟结果的分析得到以下结论:① 在断层错动过程中,下盘一侧受断层错动影响的上覆土体的应力状态经压剪→纯剪→拉剪逐渐变化,而上盘一侧上覆土体的应力状态变化较为复杂,经压剪→纯剪→拉剪→纯剪→压剪重复变化;② 在断层均匀错动过程中,断层下盘一侧土体的破裂率先出现在地表拉剪区内,随错动量的增大,破裂带向两侧、向深部扩展;同时,下盘一侧土体的底部产生破坏,并斜向上扩展,逐渐与顶部破裂相连;③ 在断层倾斜错动过程中,地表破裂出现的位置和上覆土体的厚度有关。对于厚度较大的土体,正断层倾斜错动能够在地表形成与断层走向有一定夹角、且与断层长度相比长度很短的地表破裂或地裂缝,而数值模拟可对正断层错动导致的地表破裂的模式加以补充,为研究地裂缝的形成机理和分布形式提供依据。Abstract: The rupture process of overlying soil caused by uniform movement and inclined movement of buried normal fault was studied by setting a three-dimensional numerical model. The stress state and failure style of overlying soil are respectively analyzed by using stress Lode parameter and equivalent plastic strain during fault movement, and a discrimination method of soil rupture is recommended. The conclusions are drawn as follows through analyzing the results of numerical simulation: ① As affected by fault movement, the stress state of overlying soil on the footwall side of the fault varies via compression-shear → pure-shear → tension-shear during fault movement, and the soil stress state on the upper wall side of the fault is fairly complex, which repetitively varies via compression-shear → pure-shear → tension-shear → pure-shear → compression-shear. ② For the uniform movement of the fault, the surface soil ruptures firstly occur at the tension-shear area on the footwall side of the fault, and with fault movement increased, the ruptures develop towards both sides as well as downward. Meantime, the bottom soil failures occur on the footwall side of the fault and develop obliquely upward, and finally connected with the rupture of surface soil. ③ For the inclined movement of the fault, the positions of soil rupture are relative with the thickness of overlying soil. When the overlying soil is thick, the surface soil ruptures or ground fissures occur due to the fault movement, which have an angle with the fault strike, and are much shorter than the fault. The numerical simulations can reveal the surface soil rupture patterns and will provide the basis for the studies on the origin and distributed patterns of ground fissures.
-
Keywords:
- rupture /
- overlying soil /
- stress state /
- plastic deformation /
- normal fault /
- numerical simulation
-
-
图 4 不同位置土单元应力罗德参数μσ随断层错动位移量的变化
(a) 地表土体;(b) 土体埋深为37.5 m;(c) 土体埋深为62.5 m;(d) 土体埋深为87.5 m
Figure 4. The change of stress Lode parameter of soil mass at different positions with fault dislocation
(a) Surface soil mass;(b) The soil mass buried at depth of 37.5 m;(c) The soil mass buried at depth of 62.5 m;(d) The soil mass buried at depth of 87.5 m
图 5 不同倾角的断层错动对上覆土体应力罗德参数μσ变化的影响
(a) 地表土体;(b) 土体埋深为37.5 m;(c) 土体埋深为62.5 m;(d) 土体埋深为87.5 m
Figure 5. The change of stress Lode parameter of overlying soil mass with different dip angles
(a) Surface soil mass;(b) The soil mass buried at depth of 37.5 m;(c) The soil mass buried at depth of 62.5 m;(d) The soil mass buried at depth of 87.5 m
图 6 不同位置土体的累积等效塑性应变随断层位错量的变化
(a) 地表土体;(b) 土体埋深为37.5 m;(c) 土体埋深为62.5 m;(d) 土体埋深为87.5 m
Figure 6. The change of cumulative equivalent plastic strain of soil mass at different positions with fault dislocation
(a) Surface soil mass;(b) The soil mass buried at depth of 37.5 m;(c) The soil mass buried at depth of 62.5 m;(d) The soil mass buried at depth of 87.5 m
图 7 断层倾角对累积等效塑性应变的影响
(a) 地表土体;(b) 土体埋深为37.5 m;(c) 土体埋深为62.5 m;(d) 土体埋深为87.5 m
Figure 7. The effect of fault dip angle on cumulative equivalent plastic strain
(a) Surface soil mass;(b) The soil mass buried at depth of 37.5 m;(c) The soil mass buried at depth of 62.5 m;(d) The soil mass buried at depth of 87.5 m
图 8 断层均匀错动致上覆土体破裂的3个阶段
(a) 断层错动0.82 m;(b) 断层错动1.05 m;(c) 断层错动1.28 m;(d) 断层错动2.1 m
Figure 8. The three stages of overlying soil rupture process caused by uniform fault movement
(a) The fault movement was 0.82 m;(b) The fault movement was 1.05 m;(c) The fault movement was 1.28 m;(d) The fault movement was 2.1 m
图 11 断层倾斜错动过程中上覆土体厚度对地表破裂形式的影响
(a) 土体厚度为 100 m;(b) 土体厚度为 200 m;(c) 土体厚度为 300 m;(d) 土体厚度为 400 m
Figure 11. The effect of overlying soil thickness on the surface rupture pattern during inclined fault movement
(a) The overlying soil is 100 m thick;(b) The overlying soil is 200 m thick;(c) The overlying soil is 300 m thick;(d) The overlying soil is 400 m thick
表 1 模型参数
Table 1 Model parameters
名称 变形模量
/(108Pa)泊松比 密度
/(kg·m−3)内摩擦
角/°黏聚力
/kPa土层 2.4 0.3 1 970 35 38.5 岩石 225 0.2 2 140 断层带 68 0.21 2 040 表 2 所选单元的位置及编号
Table 2 The location and number of selected elements
土体埋深/m 距段层带距离/m −200 −160 −120 −80 −40 断层带 40 80 120 160 12.5 B1 C1 D1 E1 F1 G1 H1 I1 J1 K1 37.5 B2 C2 D2 E2 F2 G2 H2 I2 J2 K2 62.5 B3 C3 D3 E3 F3 G3 H3 I3 J3 K3 87.5 B4 C4 D4 E4 F4 G4 H4 I4 J4 K4 -
陈立伟. 2007. 地裂缝扩展机理研究[D]. 西安: 长安大学: 30–48. Chen L W. 2007. Study on the Propagation Mechanism of Ground Fissures[D]. Xi’an: Chang’an University: 30–48 (in Chinese).
楚锡华,徐远杰. 2009. 基于Lode参数的应力状态描述及D-P系列准则[J]. 武汉理工大学学报,31(16):82–86 doi: 10.3963/j.issn.1671-4431.2009.16.021 Chu X H,Xu Y J. 2009. Description of stress states with lode parameters and study on D-P criteria[J]. Journal of Wuhan University of Technology,31(16):82–86 (in Chinese)
郭恩栋,冯启民,薄景山,洪峰. 2001. 覆盖土层场地地震断裂实验[J]. 地震工程与工程振动,21(3):145–149 doi: 10.3969/j.issn.1000-1301.2001.03.026 Guo E D,Feng Q M,Bo J S,Hong F. 2001. Seismic test of soil site rupture under fault displacements[J]. Earthquake Enginee-ring and Engineering Vibration,21(3):145–149 (in Chinese)
姜振泉, 武强, 隋旺华. 1999. 临汾地裂缝的成因及发育环境研究[M]. 徐州: 中国矿业大学出版社: 65–67. Jiang Z Q, Wu Q, Sui W H. 1999. Analysis on the Origin and Development Condition of Ground Fissure[M]. Xuzhou: China University of Mining and Technology Press: 65–67 (in Chinese).
李小军,赵雷,李亚琦. 2009. 断层错动引发基岩上覆土层破裂过程模拟[J]. 岩石力学与工程学报,28(增刊1):2703–2707 Li X J,Zhao L,Li Y Q. 2009. Simulation of fault movement induced rupture process of overlaying soil of bedrock[J]. Chinese Journal of Rock Mechanics and Engineering,28(S1):2703–2707 (in Chinese)
李秀菊,李鸿晶. 2012. 断层错动引起的上覆土体破裂演化规律研究[J]. 地震学报,34(6):858–864 doi: 10.3969/j.issn.0253-3782.2012.06.012 Li X J,Li H J. 2012. Analysis of rupture propagation in overlying soil due to fault movement[J]. Acta Seismologica Sinica,34(6):858–864 (in Chinese)
马野, 袁志丹, 曹金凤. 2011. ADINA有限元经典实例分析[M]. 北京: 机械工业出版社: 118–120. Ma Y, Yuan Z D, Cao J F. 2011. Classical Finite Element Analysis of ADINA[M]. Beijing: China Machine Press: 118–120. (in Chinese).
彭建兵,陈立伟,黄强兵,门玉明,范文,闫金凯,李珂,姬永尚,石玉玲. 2008. 地裂缝破裂扩展的大型物理模拟试验研究[J]. 地球物理学报,51(6):1826–1834 doi: 10.3321/j.issn:0001-5733.2008.06.024 Peng J B,Chen L W,Huang Q B,Men Y M,Fan W,Yan J K,Li K,Ji Y S,Shi Y L. 2008. Large-scale physical simulative experiment on ground-fissure expansion mechanism[J]. Chinese Journal of Geophysics,51(6):1826–1834 (in Chinese)
石玉玲,门玉明,彭建兵,黄强兵,刘洪佳,陈立伟. 2008. 西安城区地裂缝破裂扩展的数值模拟[J]. 水文地质工程地质,35(6):56–60 doi: 10.3969/j.issn.1000-3665.2008.06.013 Shi Y L,Men Y M,Peng J B,Huang Q B,Liu H J,Chen L W. 2008. Numerical simulation of ground-fissure cracking and extending in Xi’an[J]. Hydrogeology and Engineering Geology,35(6):56–60 (in Chinese)
王秀艳,王金哲,臧逸中,韩双平,陈江,李向全. 2006. 衡水地区地裂缝空间形成特征与地下水位降深关系[J]. 地球科学进展,21(4):417–423 Wang X Y,Wang J Z,Zang Y Z,Han S P,Chen J,Li X Q. 2006. Exploitation of deep groundwater and with relevant issus of earth fissures at Hengshui area in North China[J]. Advances in Earth Science,21(4):417–423 (in Chinese)
王仲仁. 2006. Lode参数的物理实质及其对塑性流动的影响[J]. 固体力学学报,27(3):277–282 doi: 10.3969/j.issn.0254-7805.2006.03.010 Wang Z R. 2006. Physical essence of Lode parameter and its effect on plastic flow[J]. Acta Mechanica Solida Sinica,27(3):277–282 (in Chinese)
吴忱. 2008. 华北地貌环境及其形成演化[M]. 北京: 科学出版社: 116–119. Wu C. 2008. Ground Environment and Its Evolution in North China[M]. Beijing: Science Press: 116–119 (in Chinese).
许立青,李三忠,索艳慧,刘鑫,戴黎明,吴奇,王鹏程,张丙坤. 2013. 华北地块南部断裂体系新构造活动特征[J]. 地学前缘,20(4):75–87 Xu L Q,Li S Z,Suo Y H,Liu X,Dai L M,Wu Q,Wang P C,Zhang B K. 2013. Neotectonic activity and its kinematics of fault system in the south of North China Block[J]. Earth Science Frontiers,20(4):75–87 (in Chinese)
赵雷,李小军,霍达. 2007a. 断层错动引发基岩上覆土层破裂问题[J]. 北京工业大学学报,33(1):20–25 Zhao L,Li X J,Huo D. 2007a. Problems of rupturing process of overlaying soil due to fault dislocation of bedrock[J]. Journal of Beijing University of Technology,33(1):20–25 (in Chinese)
赵雷,李小军,霍达. 2007b. 数值模拟软夹层对基岩上覆土层破裂的影响[J]. 北京工业大学学报,33(3):289–292 Zhao L,Li X J,Huo D. 2007b. Numerically simulate the response complexion of the overlaying soil with soft interlayer due to fault bedrock dislocation[J]. Journal of Beijing University of Technology,33(3):289–292 (in Chinese)
庄妍,王康宇. 2016. 基于Von-Mises屈服准则的结构安定性研究[J]. 地下空间与工程学报,12(增刊1):170–174,191 Zhuang Y,Wang K Y. 2016. Shakedown analysis of structures obeying Von-Mises criterion[J]. Chinese Journal of Underground Space and Engineering,12(S1):170–174,191 (in Chinese)
Bray J D,Seed R B. 1994. Analysis of earthquake fault rupture propagation through cohesive soil[J]. J Geotech Eng,120(3):562–580 doi: 10.1061/(ASCE)0733-9410(1994)120:3(562)
Hernandez-Marin M,Burbey T J. 2012. Fault-controlled deformation and stress from pumping-induced groundwater flow[J]. J Hydrol,428-429:80–93 doi: 10.1016/j.jhydrol.2012.01.025
Loukidis D,Bouckovalas G D,Papadimitriou A G. 2009. Analysis of fault rupture propagation through uniform soil cover[J]. Soil Dyn Earthquake Eng,29(11/12):1389–1404
Ng C W W,Cai Q P,Hu P. 2012. Centrifuge and numerical modeling of normal fault-rupture propagation in clay with and without a preexisting fracture[J]. J Geotechn Geoenviron Eng,138(12):1492–1502 doi: 10.1061/(ASCE)GT.1943-5606.0000719
Sun P,Peng J B,Chen L W,Yin Y P,Wu S R. 2009. Weak tensile characteristics of loess in China:An important reason for ground fissures[J]. ENG GEOL,108(2009):153–159
Taniyama H, Watanabe H. 2000. Deformation of sandy deposits by fault movement[C]//Proceedings of the 12th WCEE. Tokyo: McGraw Hill: 1–6.
Xu L Q,Li S Z,Cao X Z,Somerville I D,Suo Y H,Liu X,Dai L M,Zhao S J,Guo L L,Wang P C,Cao H H. 2016. Holocene intracontinental deformation of the northern North China Plain:Evidence of tectonic ground fissures[J]. J Asian Earth Sci,119:49–64 doi: 10.1016/j.jseaes.2016.01.003