水压力作用下三峡库区侏罗系软岩裂纹扩展规律及力学机制

简文星; 潘永亮; 李林均; 李豪; 徐长江

doi:10.19509/j.cnki.dzkq.2022.0036

水压力作用下三峡库区侏罗系软岩裂纹扩展规律及力学机制

doi: 10.19509/j.cnki.dzkq.2022.0036

1.
中国地质大学(武汉)工程学院, 武汉 430074
2.
中国市政工程中南设计研究总院有限公司, 武汉 430015
3.
重庆市勘测院, 重庆 401121

基金项目:

国家自然科学基金项目“三峡库区典型顺向岸坡库水与降雨联合作用失稳观测与理论解析” 41272306

详细信息

作者简介:
简文星(1967—)，男，教授，主要从事工程地质与岩土工程方面的科研与教学工作。E-mail: wxjian@cug.edu.cn

通讯作者:
潘永亮(1995—)，男，助理工程师，主要从事岩土工程与地质灾害方面的勘察设计研究工作。E-mail：934732201@qq.com

中图分类号: TU41
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- 文章访问数: 1545
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- 被引次数: 0
出版历程
- 收稿日期: 2021-12-21

Crack propagation law and mechanical mechanism of Jurassic soft rock in the Three Gorges Reservoir area under water pressure

1.
Faculity of Engineeing, China University of Geosciences(Wuhan), Wuhan 430074, China
2.
Central & Southen China Municipal Engineering Design and Research Institute Co., Ltd., Wuhan 430015, China
3.
Chongqing Survey Institute, Chongqing 401121, China

摘要

摘要:
三峡库区侏罗系地层滑坡发育广泛，研究该地层软岩夹层在不同水压力作用下的强度及变形破坏特性对库区岸坡的长期稳定性评价具有重要理论指导意义。以三峡库区侏罗系典型软岩——沙溪庙组泥质粉砂岩为例，对其进行了不同水压力下的力学试验系统(MTS)三轴压缩试验，并基于断裂力学与有效应力原理对水-力耦合效应下岩石的起裂及裂纹扩展机制进行了分析。研究结果表明：水压力的存在可降低岩石的峰值抗压强度，水压力越大岩石破坏后控制性裂纹的长度及倾角也总体随之增大，次生裂纹的数目也呈现出随之增多的趋势；原生裂纹的起裂及次生裂纹的扩展分别受控于K_Ⅱ、K_Ⅰ型应力强度因子，原生裂纹的起裂角最大为70.5°；次生裂纹的临界扩展长度随原生裂纹长度的增加而增大，当原生裂纹倾角约为45°时，在相同条件下次生裂纹的扩展长度最大；说明水压力的存在加剧了岩石裂纹的扩展，且使岩石的张拉破坏趋势更为明显，而原生裂纹形态特征对裂纹的扩展规律亦具有较大的影响。
- 三峡库区 /
- 侏罗系软岩 /
- 水压力 /
- 裂纹扩展 /
- 力学机制
Abstract:
Jurassic landslides are widely developed in the Three Gorges Reservoir area. The study of the strength and deformation failure characteristics of the soft rock interlayer under different water pressures is of great theoretical significance to the long-term stability evaluation of the reservoir bank slope. MTS triaxial compression tests were carried out on the argillaceous siltstone of Shaximiao Formation, a typical soft rock of Jurassic in the Three Gorges Reservoir area, to study the strength and deformation damage characteristics of the rock under different water pressures. Based on fracture mechanics and effective stress principle, the mechanism of crack initiation and crack propagation under hydro-mechanical coupling effect was analyzed. It was found that water pressure can reduce the peak compressive strength of rock. With the increase of water pressure, the length and dip angle of dominant cracks increase, and the number of secondary cracks also shows a trend of increasing. The primary crack initiation and secondary crack propagation were controlled by K_Ⅱ and K_Ⅰ stress intensity factors, respectively. The maximum initiation angle of the primary crack was 70.5°. The critical propagation length of the secondary crack increases with the increase of the primary crack length. When the dip angle of the primary crack is about 45°, the propagation length of the secondary crack reaches the maximum under the same conditions. The results show that the existence of water pressure is conducive to the crack propagation, and the geometric characteristics of primary cracks also have a great influence on the crack propagation law.This study provides some theoretical guidance for the long-term stability evaluation of the reservoir bank rock mass.
- Three Gorges Reservoir area /
- Jurassic soft rock /
- water pressure /
- crack propagation /
- mechanical mechanism

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图 1 试验所用标准岩样

Figure 1. Standard rock samples used for testing

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图 2 侏罗系软岩单轴压缩试验曲线

Figure 2. Uniaxial compression test curve of Jurassic soft rock

下载: 全尺寸图片幻灯片

图 3 不同水压力作用下侏罗系软岩应力-应变曲线

Figure 3. Stress and strain curve of Jurassic soft rocks under different water pressures

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图 4 不同水压力作用下侏罗系软岩的破坏形态与裂纹发育特征

Figure 4. Destruction morphology and crack development characteristics of Jurassic soft rocks under different water pressures

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图 5 侏罗系泥质粉砂岩受力分析过程简化示意

σ₁.轴向压力；σ₃.围岩；p_w.水压力；α.裂纹与竖直方向的夹角；2a.裂缝长度；σ_n.正应力；τ_n.剪应力；下同

Figure 5. Simplified diagram of the stress analysis process of Jurassic argillaceous siltstone

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图 6 原生微裂纹受力起裂产生次生翼型裂纹

Figure 6. Primary microcracks cracked by stress to produce secondary airfoil cracks

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图 7 三轴压缩及水压力作用下岩样受力简化示意图

θ.次生纹与原生微裂纹之间的夹角；T.剪应力在原生裂纹端点产生的集中应力；Tsinα.垂直于次生裂纹的应力分量；l.次生裂纹的长度；其他物理量的含义同图 5

Figure 7. Schematic diagram of the stress of the rock sample under triaxial compression and water pressure

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图 8 岩样三轴压缩试验裂纹贯通破坏过程

Figure 8. Crack through failure process of rock samples under triaxial compression

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图 9 水压力及原生微裂纹形态特征对次生裂纹扩展的影响

Figure 9. Effects of water pressure and primary microcrack geometry on secondary crack propagation

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表 1 不同水压力作用下侏罗系软岩的破坏特征统计

Table 1. Damage characteristic statistics of Jurassic soft rocks under different water pressures

围压/MPa	水压力/ MPa	最大剪切裂纹长度/cm	宏观破坏面与水平面夹角/(°)
2	0	7.6	55
	0.1	8.5	70
	0.3	10.5	67
	0.5	10.8	69
	0.8	9.4	74
	1.0	11.5	76

下载: 导出CSV

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