基于三维裂隙网络模拟和单孔压水试验的裂隙张开度确定方法

程锦波; 夏露; 于青春

doi:10.19509/j.cnki.dzkq.tb20230128

基于三维裂隙网络模拟和单孔压水试验的裂隙张开度确定方法

doi: 10.19509/j.cnki.dzkq.tb20230128

中国地质大学(北京)水资源与环境学院, 北京 100083

详细信息

作者简介:
程锦波, E-mail: cjb@cugb.edu.cn

通讯作者:
于青春, E-mail: yuqch@cugb.edu.cn

中图分类号: P641.135
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- 文章访问数: 240
- PDF下载量: 77
- 被引次数: 0
出版历程
- 收稿日期: 2023-03-13
- 录用日期: 2023-06-26
- 修回日期: 2023-04-28

Determination method of fracture aperture based on three-dimensional fracture network simulation and water injection tests

College of Water Resources and Environment, China University of Geosciences(Beijing), Beijing 100083, China

More Information

Author Bio:
CHENG Jinbo, E-mail: cjb@cugb.edu.cn

Corresponding author: YU Qingchun, E-mail: yuqch@cugb.edu.cn

摘要

摘要:
岩体裂隙的等效水力张开度(水力学等效隙宽)是岩体的关键力学几何参数之一。目前常采用交叉孔试验等大型试验方法获取野外深部岩体裂隙的张开度, 但该方法很少在一个工程中多次使用, 且难以分析裂隙张开度在空间上的变化。以三峡大坝右岸地下电站硐室围岩为例, 提出了一种联合利用常规单孔压水试验数据和三维裂隙网络模拟, 反演确定裂隙等效水力张开度的新方法。利用实测裂隙编录资料取得的统计数据开展裂隙产状随机模拟, 构建与压水试验钻孔连通的三维离散裂隙网络渗流模型, 拟合单孔压水稳态流量和压力的关系, 反演不同深度岩体的裂隙等效水力张开度。结果表明, 研究区岩体裂隙的等效水力张开度一般为0.07~0.30 mm, 符合对数正态分布的统计特征, 多数钻孔反演的裂隙等效水力张开度随埋深呈指数形式衰减, 少数钻孔呈现出裂隙等效水力张开度随机性强、随埋深变化不明显的特征。相较传统方法, 本方法反演结果显著不同, 有待进一步验证。
- 裂隙岩体 /
- 裂隙张开度 /
- 离散裂隙网络模型 /
- 数值模拟 /
- 压水试验 /
- 三峡大坝
Abstract: Objective
The aperture of fractures (hydraulic equivalent aperture of fractures) of rock fractures is one of the key mechanical parameters of rocks.It has significant indicative significance in water conservancy projects, geological surveys and so on.At present, large-scale test methods such as cross-hole tests are often used to obtain the fracture apertures of deep rock masses in the field, but this method is rarely used many times in projects, and it is difficult to analyse the spatial variation in the aperture of fractures. This spatial variation is precisely what we need to focus on and discuss because it affects the accurate definition and application of the hydraulic equivalent fracture aperture in engineering applications.
Methods
In this paper, taking the surrounding rock of an underground power station cavern on the right bank of the Three Gorges Dam as an example, a new inversion method for determining the hydraulic equivalent aperture of fractures is proposed by using conventional single-hole water injection test data and three-dimensional fracture network simulation. The statistical data obtained from the measured fracture cataloguing data are used to carry out random simulation of fracture characteristics, and a three-dimensional discrete fracture network seepage model connected with water injection test boreholes is constructed to fit the relationship between the single-hole steady-state flow rate and injection. The hydraulic equivalent apertures of fractures at different depths of rocks are inverted.
Results
The results show that the hydraulic equivalent aperture of fractures in the research area is generally 0.07-0.30 mm, which confirms to the statistical characteristics of the log-normal distribution. Most of the inverted hydraulic equivalent apertures of fractures in boreholes decrease exponentially with burial depth, while a few boreholes show strong randomness of the hydraulic equivalent aperture of fractures and no obvious change with burial depth.
Conclusion
Compared to those of traditional methods, the inversion results of this approach are significantly different and require further verification.
- fracture rock mass /
- fractures aperture /
- discrete fracture network model /
- numerical simulation /
- water injection test /
- Three Gorges Dam
注释:

所有作者声明不存在利益冲突。

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图 1 三维裂隙网络随机模型

a.大范围直角坐标系裂隙网络; b.裁剪压水试验钻孔附近棱柱体内裂隙网络

Figure 1. Three-dimensional stochastic fracture network

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图 2 3013主硐左壁裂隙编录图

Figure 2. Mapped fractures on the left wall of the 3013 main tunnel

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图 3 不同区段裂隙倾向倾角等密图

Figure 3. Fracture dip direction and dip angle isodense graph for different segments

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图 4 不同区段实测裂隙产状的施密特极点图

Figure 4. Schmidt net of measured fractures in each section

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图 5 各区段实测裂隙迹线长度频率分布图

Figure 5. Trace length frequency distribution histogram of measured fractures in each section

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图 6 岩体透水率随试段埋深的变化

Figure 6. Variation in the rock mass permeability with the burial depth of the test section

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图 7 利用式(7)反算的裂隙等效水力张开度随埋深的变化

Figure 7. Variation in the equivalent hydraulic aperture of fractures with burial depth was calculated via the inverse method(7)

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图 8 某试段20次压水试验流量

Figure 8. Flow rate of 20 injection water tests in a test section

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图 9 张开度的频率分布柱状图及拟合曲线

Figure 9. Frequency distribution histogram and fitting curve of the equivalent hydraulic aperture of fractures

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图 10 多组裂隙平均等效水力张开度随试段埋深的变化

Figure 10. Average equivalent hydraulic aperture of fractures of multiple fractures changes with the burial depth of the test section

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表 1 各区段裂隙一维密度统计结果

Table 1. One-dimensional density calculation results for the fractures in each section

区段编号	初始测距/m	终止测距/m	一维密度/m^-1
A	0	35	1.06
B	35	170	1.14
C	170	235	1.03
D	235	360	0.85

下载: 导出CSV

表 2 各区段实测裂隙统计特征

Table 2. Statistical characteristics of the measured fractures in each section

区段	裂隙组	平均倾向/(°)	平均倾角/(°)	Fish分布K值	迹长均值/m	迹长标准差/m	一维密度/m^-1
A	1	85.5	36.6	15.8	2.05	0.43	0.31
	2	172.5	89.5	28.2	1.67	0.34	0.57
	3	291.7	58.7	14.1	2.78	0.75	0.17
B	1	107.1	38.7	7.7	1.58	0.84	0.41
	2	242.9	70.6	6.8	1.39	0.54	0.37
	3	355.3	69.2	8.3	1.54	0.80	0.33
C	1	29.4	72.4	5.9	1.56	0.48	0.38
	2	110.5	30.2	14.6	2.70	1.46	0.45
	3	285.9	64.5	6.1	1.58	0.98	0.20
D	1	100.3	46.7	10.0	2.25	0.87	0.32
	2	235.3	38.1	6.8	2.13	0.97	0.27
	3	347.1	72.7	5.7	2.16	1.22	0.26

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表 3 各区段模拟裂隙统计特征

Table 3. Statistical characteristics of the simulated fractures in each section

区段	裂隙组	迹长均值/m	迹长标准差/m	三维密度/m^-3	直径均值/m	直径标准差/m
	1	1.89	0.39	0.17	1.92	0.27
A	2	1.61	0.30	0.24	1.82	0.38
	3	2.76	0.52	0.03	2.42	0.34
	1	1.62	1.08	0.06	1.73	1.06
B	2	1.39	0.57	0.30	1.59	0.62
	3	1.48	0.83	0.09	1.68	0.69
	1	1.74	0.70	0.32	1.53	0.47
C	2	2.97	1.47	0.04	2.23	1.07
	3	1.60	0.86	0.24	1.41	0.66
	1	2.60	0.87	0.06	2.09	0.72
D	2	2.46	0.95	0.14	2.02	0.90
	3	3.50	1.14	0.01	2.65	1.48

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表 4 裂隙网络模拟反演的等效水力张开度均值

Table 4. Mean equivalent hydraulic aperture of fractures inversely estimated from fracture-network simulation

区段		A	B	C	D
区段		张开度均值/mm
裂隙组	1	0.195	0.108	0.113	0.081
	2	0.202	0.112	0.112	0.078
	3	0.201	0.104	0.110	0.083

下载: 导出CSV

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