Study on Feature of Surface Rupture and Deformation Caused by Buried Normal Fault Movement
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摘要: 通过建立三维计算模型,对隐伏正断层在均匀错动、倾斜错动和翘倾错动方式下地表土体的应力路径、破裂和变形特征进行了研究。根据地表破裂临界值,分析了工程建设“避让带”的宽度和起始位置的变化特征。根据行业规范,提出工程建设“关注带”的确定方法,分析了“关注带”的宽度和起始位置的变化特征,得到以下主要结论:①在断层错动过程中,位于两侧的地表土体应力路径变化明显不同,下盘一侧和上盘一侧分别以三轴拉伸和三轴压缩为主;②地表强变形带与地表破裂带的分布并不一致,需要综合考虑等效塑性应变和总位移比2个指标来评价同震地表错动对建筑物的影响;③当隐伏断层错动的垂直位移达到3m时,工程建设“避让带”的宽度在10—90m范围内变化,受上覆土体厚度和断层倾角的影响最大,而工程建设“关注带”的宽度在150—400m范围内变化,受上覆土体的性质影响最大。Abstract: The serious seismic disaster is often limited in a narrow zone along the fault strike, thus the study on the surface rupture zone and strong deformation zone on both sides of fault is of great significance for engineering seismic fortification. In this paper, a three-dimensional finite element model was constituted to study the stress path, rupture and deformation of surface soil mass caused by the uniform movement, inclined movemen and warped movement of buried normal fault. Based on the critical value of surface rupture, the variation features and influencing factors of width and starting position of the "avoiding zone" in engineering construction are analyzed in accordance to industry standards. The main results are as follows:① the variations of stress path are obviously different for the surface soil on upper wall to footwall of the fault, and are respecively triaxial-tension and triaxial-compression stress state. ② The distribution of strong deformation zone is not consistent with that of rupture zone, so it is necessary to consider the equivalent plastic strain and the total displacement ratio to evaluate the effect of the seismic ground movement on buildings. ③ When the vertical displacement of buried fault is 3m, the width of "avoiding zone" in engineering construction changes within the range of 10-90 m, which is most affected by the thickness of overlying soil and the fault dip angle, whereas the width of "attention zone" in engineering construction changes within the range of 150-400 m, which is most affected by the properties of overlying soil mass.
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Key words:
- Buried normal fault /
- Surface rupture /
- Stress path /
- Avoiding zone /
- Attention zone
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表 1 模型参数
Table 1. Model parameters
名称 变形模量/Pa 泊松比 密度/kg·m-3 内摩擦角/° 黏聚力/kPa 土层 2.4x108 0.3 1970 35 38.5 岩石 2.25x1010 0.2 2140 断层带 6.8x109 0.21 2040 表 2 节点的位置及编号
Table 2. The location and number of the nodes
节点号 距离/m 1 -289.5 2 -267.0 3 -245.8 4 -225.8 5 -207.0 6 -189.3 7 -172.6 8 -156.9 9 -142.1 10 -128.2 11 -115.1 12 -102.7 13 -91.0 14 -80.1 15 -69.7 16 -60.0 17 -50.8 18 -42.2 19 -34.1 20 -26.4 21 -19.2 22 -12.4 23 -6.0 24 0 25 6.2 26 12.7 27 19.7 28 27.1 29 35.0 30 43.3 31 52.2 32 61.6 33 71.5 34 82.1 35 93.4 36 105.3 37 118.0 38 131.5 39 145.8 40 161.0 41 177.1 42 194.2 43 212.4 44 231.7 -
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