剪胀对复杂裂隙岩体渗透性影响的离散元分析

李小琴; 李文平

doi:10.13544/j.cnki.jeg.2014.05.06

剪胀对复杂裂隙岩体渗透性影响的离散元分析

doi: 10.13544/j.cnki.jeg.2014.05.06

李小琴^1,2,
李文平^1,2

1.
中国矿业大学深部岩土力学与地下工程国家重点实验室徐州 221116;
2.
中国矿业大学资源与地球科学学院徐州 221116

基金项目:

国家自然科学基金资助项目（41172290），中央高校基本科研业务费专项资金（2012QNA63），江苏高校优势学科建设工程项目资助

详细信息

作者简介:
李小琴，女，副教授，博士，主要从事工程地质水文地质研究方面的工作. Email: cumtlxq@126.com

中图分类号: P641
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出版历程
- 收稿日期: 2014-04-08
- 修回日期: 2014-07-30
- 刊出日期: 2014-10-25

UDEC BASED NUMERICAL STUDY ON PERMEABILITY OF FRACTURED ROCK MASS WITH SHEAR DILATION

LI Xiaoqin^1,2,
LI Wenping^1,2

1.
State Key Laboratory for Geomechanics & Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116;
2.
School of Resource and Geoscience, China University of Mining and Technology, Xuzhou 221116

摘要

摘要: 裂隙岩体流固耦合问题是目前国内外研究热点之一，采用离散元软件UDEC对裂隙岩体发生节理剪胀的渗透性变化规律进行了模拟分析。基于现场调查的裂隙信息统计生成裂隙网络岩体模型。通过固定垂直应力、不断增加应力比RS(RS=水平应力/垂直应力)使岩体出现剪胀，采用库伦滑移节理模式对岩体在剪胀过程中的渗透性变化情况进行模拟。结果发现：当应力比较小(RS3.1)时，节理水力隙宽、流速、渗透系数等参数都随着应力比的增加表现出明显的降低；而当岩体出现剪胀现象之后(应力比大于3.1)，发生剪切滑移和剪胀现象的节理控制着裂隙岩体的总体渗流行为，与不考虑节理剪胀的计算结果相比，岩体渗透能力出现了显著增长。这一结果表明，剪胀对裂隙岩体渗透性的影响是显著而不可忽视的。
- 裂隙岩体 /
- 离散元 /
- 渗透性 /
- 应力比 /
- 剪胀
Abstract: The hydro-mechanical coupling of fractured rock mass is a hot research focus at home and abroad recently. The fractures(or joints) of the rock mass play the main pathways of the fluid flow in fractured rock masses. The apertures of the fractures play an important role in the fluid flow. Both the shear stress-induced dilations and the normal closures or openings induced by normal stress can change the fracture apertures. The permeability of fractured rock mass by taking in account the shear dilation is studied in this paper. It uses the UDEC. The realistic discrete fracture network of sandstone is generated using the joint information from the in-situ survey and the Monte-Carlo Method. The permeability changes of the fracture network rock are simulated by increasing the stress ratio RS(RS=horizontal stress/vertical stress) while keeping the vertical stress constant. The shear dilation of the fractures are considered using the Cloumb slip joint model. The results show that all of the hydraulic apertures, the fluids velocity and the permeability coefficient of the fractured rock mass decrease with the increment of the stress ratio during the stress ratios are enough small(RS is small than 3.1). However, they increase with the increment of stress ratio when the stress ratios are enough large to cause the shear dilation of the fractures(RS is large than 3.1). When the stress ratio is large enough, both the overall permeability and flow patterns are controlled by the fractures which are observed to have shear slipping and dilation phenomenon. During the stress ratio increase from 0.5 to 3.1,the permeability coefficient of the fractured rock masses considering the joint shear dilation is the same to that of disconsidering joint shear dilation. It shows that no shear dilation appears in the fractured rock masses when the stress ratios are enough small. When the stress ratio is more than 3.1,the permeability of rock masses considering the shear dilation increases significantly, but that of disconsidering shear dilation joints decreases slowly. The former is about 2～3 orders of the magnitude more than the latter when the stress ratio exceeds 3.1. The results show that the shear-induced flow channeling has very important impact on the permeability of the fractured rock mass, which shouldn't be neglected.
- Fractured rock mass /
- Distinct element method /
- Permeability /
- Stress ratio /
- Shear dilation

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