地球物理学报  2011, Vol. 54 Issue (9): 2293-2301 PDF

1. 北京市地震局,北京 100080;
2. 香港科技大学,香港;
3. 中国水利水电科学研究院,北京 100038

Centrifuge modeling on the behavior of co-seismic fault dislocation in the Quaternary stratum
HU Ping1, DING Yan-Hui1, CAI Qi-Peng2, LUO Guan-Yong2, WU Hong-Wei2, HOU Yu-Jing3, DONG Ming3
1. Earthquake Administration of Beijing Municipality, Beijing 100080, China;
2. Hong Kong University of Science and Technology, HKSAR, China;
3. 3 China Institute of Water Resources and Hydropower Research, Beijing 100038, China
Abstract: In this thesis, a series of centrifuge model tests focusing on the behavior of co-seismic fault dislocation in the Quaternary stratum are reported and discussed. An original technique that embeds a pre-existing fault in the centrifuge model is proposed and adopted. Faults with different activity ages or with different embedding depths in the Quaternary stratum were simulated by changing the depth of the tip of the pre-existing faults in the centrifuge model. The process of fault dislocation, fault rupture propagation, characteristics of the ground surface rupture, and the ground surface deformation are studied. Based on the centrifuge test results, setback distances in different ground conditions are identified.
Key words: Behavior of co-seismic fault dislocation      Centrifuge modeling      Pre-existing fracture      Avoidance distance
1 引言

1) 董津城、曹佑裕、刘守华、徐光明、蔡正银等.发震断裂上覆土层厚度对工程影响离心模拟试验研究报告.1999.10.

2 离心机模拟试验的基本原理

3 第四纪活动断层的离心机试验模型设计

 图 1 离心机试验箱体装置与预制断层模型 Fig. 1 Centrifuge model package and soil model with a pre-existing fault

4 试验要素 4.1 试验选用离心机

4.2 模型制作

 图 2 粘土和砂土的级配曲线及物性指标 Fig. 2 Gradation curve and physical index of clay and sand

4.3 试验测量、观察

 图 3 测量、观察设备布置图 Fig. 3 Details of instrumentation in centrifuge test
4.4 基岩错动量与地震烈度

5 试验现象分析及结果 5.1 第四纪覆盖层为单一粘土的情况

 图 4 粘土模型试验现象及测量结果 Fig. 4 Test results in clay

(1) 不同预制断层上断点埋深的同震错动行为不同

(2) 不同地震烈度对其同震错动行为作用不同

(3) 相同基岩错动量一步和多步错动完成对其同震错动行为作用不同

(4) 相同基岩错动量不同错动速度对试验现象无明显不同

5.2 第四纪覆盖层为单一砂土的情况

 图 5 砂土模型试验现象及测量结果 Fig. 5 Test results in sand
5.2.1 不同预制断层上断点埋深的同震错动行为不同

5.2.2 不同地震烈度同震错动行为表现出显著差别

5.2.3 相同基岩错动量一步和多步错动完成对其同震错动行为没有明显影响

5.2.4 相同基岩错动量不同错动速度对试验现象无明显不同

5.3 第四纪覆盖层为粘土-砂土互层的情况

 图 6 互层模型试验现象及测量结果 Fig. 6 Test results in clay-sand multilayer models
5.3.1 互层层数对同震错动行为影响不大

10号3 层模型试验由于基岩错动量较小(仅0.53m, 为摸索控制错动量的初期试验)，没有出现明显的试验现象(尚找不到其他原因).11号五层和13号九层模型试验错动量分别为0.75m 和0.66m, 地表破裂宽度相同、位置也相同位于1-1′线近旁；11号五层模型试验地表破裂深度为8.3 m, 没有穿透厚14.8m 的第一层粘土层，而几个九层模型试验地表破裂均穿透厚为7.0m 的第一层粘土，并立即止于下一层砂土顶面.互层试验中没有发现互层层数对同震错动行为的明显影响.

5.3.2 砂土层的隔震作用显著

5.3.3 不同预制断层上断点埋深同震错动行为特点

6 结论

(1) 地表形变

(2) 地表破裂

(3) 地表破裂的避让距离

(4) 其他相关认识

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