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自2003年三峡库区启动蓄水工程以来，位于巴东库地段的地震频发态势已引起学术界的广泛关注。这些地震多集中在高桥断裂区域，经初步研究，地震活动与该地段由陡及缓的犁式断层构造密切相关。为了深入探究地质构造和地层岩性对地震触发机制的影响，本文基于库区高桥断裂的构造特征，在岩样中设计了具有不同定倾角和变倾角节理的模型，并开展了室内三轴试验进行对比分析。研究结果表明，灰岩岩样的力学特性和破坏特征受到岩样节理面形态的影响，包括单一角度倾角和变倾角节理面。通过引入变倾角节理的灰岩岩样并结合力学分析，发现沿着节理面滑动时的剪应力不断积累，导致内部应力集中，破坏时在较大倾角向较小倾角转变的地方产生明显的水平向裂纹。在岩样的“节理倾角较缓区域”更易产生次生裂纹。本文提出了计算变倾角节理面剪应力的方法。这些研究结果对于库区高发地震区域的防灾减灾工作具有一定的参考价值。
Abstract：Since the impoundment of the Three Gorges Reservoir in 2003, the frequent earthquakes in the Badong Reservoir area have attracted wide attention from the academic community. These earthquakes are mostly concentrated in the Gaoqiao fault area. After preliminary research, the seismic activity is closely related to the steep and gentle plough fault structure in this area. In order to further explore the influence of geological structure and formation lithology on earthquake triggering mechanism, based on the structural characteristics of Gaoqiao fault in reservoir area, this paper designs models with different fixed dip angles and variable dip angles joints in rock samples, and carries out indoor triaxial tests for comparative analysis. The result show that the mechanical properties and failure characteristics of limestone rock samples are affected by the joint surface morphology of rock samples, including single angle dip angle and variable dip angle joint surface. By introducing limestone rock samples with variable dip joints and combining with mechanical analysis, it is found that the shear stress accumulates continuously when sliding along the joint surface, [Results]ing in internal stress concentration, and obvious horizontal cracks are generated at the place where the larger dip angle changes to the smaller dip angle. Secondary cracks are more likely to occur in the ‘joint inclination area' of rock samples. In this paper, a method for calculating the shear stress of joint surface with variable dip angle is proposed. These research result have certain reference value for the disaster prevention and mitigation work in the high-incidence earthquake area of the reservoir area.
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基本信息:
DOI：10.13928/j.cnki.wrahe.2024.S2.098
中图分类号:TV223.1
引用信息:
[1]魏寅平,李飞,段国勇,等.变倾角灰岩三轴力学特性分析[J].水利水电技术(中英文),2024,55(S2):649-655.DOI:10.13928/j.cnki.wrahe.2024.S2.098.
基金信息:
国家自然科学基金联合基金项目“高速铁路开控卸荷条件下泥岩松弛-湿胀耦合作用机理与基底微膨胀变形控制技术研究”(U2034203);国家自然科学基金联合基金项目“三峡库区消落带岩体劣化机理与微生物改性加固研究”(U22A20600); 2023年度宜昌市自然科学研究项目(A23-2-047); 湖北省教育厅2022年度科研计划项目(B2022567)
2024-09-20
2024-09-20