Intelligent Inversion of Mechanical Parameters of Surrounding Rock of Underground Water-Sealed Storage Cavern During Construction

doi:10.11988/ckyyb.20231376

Abstract

Abstract:

Reasonably and accurately determining the mechanical parameters of surrounding rock is crucial for the stability analysis of surrounding rock and the design of supporting structures during the construction of underground water-sealed storage caverns. Based on the engineering geological characteristics of underground water-sealed storage caverns, an intelligent inversion method for the mechanical parameters of surrounding rock during construction is proposed for the equivalent continuous medium model. First, the constitutive model of the cavern rock mass is determined via laboratory and numerical tests. Then, the mechanical parameters of the constitutive model are estimated using the Hoek-Brown strength criterion and other methods, and the sensitivity of each parameter to the deformation and relaxation of the surrounding rock is analyzed. Based on these analyses, an orthogonal test scheme for the parameters to be inverted is designed. Finally, an intelligent inversion model for the mechanical parameters of the surrounding rock is constructed using samples obtained from numerical simulations and an evolutionary neural network model. Comprehensively estimating the initial value ranges of the mechanical parameters of the surrounding rock for different classes of rock mass basic quality can avoid large deviations in inversion results caused by the wide optimization range of intelligent algorithms. Sensitivity analysis of the mechanical parameters to the deformation and relaxation of the surrounding rock can reduce the number of inversion parameters. The proposed intelligent inversion method is applied to a typical underground water-sealed storage cavern project in Shandong Province. Results show that the relative errors of the settlement of the peripheral rock vault, the maximum displacement of the cavern circumference, the internal deformation, and the average depth of relaxation are all less than 10%, meeting the precision requirements of engineering applications. Therefore, the proposed intelligent inversion method exhibits high feasibility and reliability through practical application and can serve as a reference for similar projects.

Key words: underground water-sealed storage cavern, stability of surrounding rock, equivalent continuous medium model for surrounding rock, mechanical parameters, Hoek-Brown strength criterion, intelligent inversion, constitutive model for rock mass

CLC Number:

P642.2

CAO Yang-bing, CHEN Ke-xin, HUANG Yue, LI Yao, ZHANG Sui, HUANG Zhen-ping. Intelligent Inversion of Mechanical Parameters of Surrounding Rock of Underground Water-Sealed Storage Cavern During Construction[J]. Journal of Changjiang River Scientific Research Institute, 2025, 42(4): 149-158.

Figures/Tables 15

Fig.1 Flowchart of intelligent inversion of mechanical parameters of surrounding rock of underground water-sealed storage cavern during construction

Fig.2 Numerical model of the cavern

Fig.3 Mechanical test results of intact rock and the joint

Table 1 Mechanics test results of the intact rock

围压σ₃/ MPa	轴向应力 σ₁/MPa	弹性模量 E/GPa	泊松比μ	黏聚力 c/MPa	内摩擦角φ/(°)	抗拉强度 σ_t/MPa
0	86.4
5	100.1	27.5	0.19	17.09	43.61	11.32
10	128.2
15	167.8

Table 2 Results of direct shear test on granite joint

结构面粗糙度系数JRC	初始法向应力σ_n0/MPa	峰值剪切位移μ_p/mm	峰值剪切应力τ_p/MPa	残余剪切应力τ_res/MPa
	4	1.197	5.84	4.02
10	6	1.372	7.25	5.53
	8	1.688	10.10	6.46

Fig.4 Numerical test model and its results

Table 3 Mechanical parameters of rock mass estimated by Hoek-Brown strength criterion

Q	GSI	GSI_r	${σ_{3}}_{m a x}$	弹性模量 E/GPa	峰值黏聚力 c/MPa	峰值内摩擦角φ/(°)	抗拉强度 σ_t/MPa	残余黏聚力 c_r/MPa	残余内摩擦角φ_r/(°)
3	53.9	26.2	4.95	10.8	2.2	52.0	0.077	1.3	43.8
4	56.5	26.5	4.97	12.6	2.3	52.7	0.094	1.4	43.9
5	58.5	26.7	4.98	14.1	2.4	53.2	0.109	1.4	44.0
6	60.1	26.9	4.99	15.5	2.5	53.6	0.123	1.4	44.1
7	61.5	27.0	5.00	16.8	2.5	53.9	0.137	1.4	44.1

Table 3 Mechanical parameters of rock mass estimated by Hoek-Brown strength criterion

Q	GSI	GSI_r	${σ_{3}}_{m a x}$	弹性模量 E/GPa	峰值黏聚力 c/MPa	峰值内摩擦角φ/(°)	抗拉强度 σ_t/MPa	残余黏聚力 c_r/MPa	残余内摩擦角φ_r/(°)
3	53.9	26.2	4.95	10.8	2.2	52.0	0.077	1.3	43.8
4	56.5	26.5	4.97	12.6	2.3	52.7	0.094	1.4	43.9
5	58.5	26.7	4.98	14.1	2.4	53.2	0.109	1.4	44.0
6	60.1	26.9	4.99	15.5	2.5	53.6	0.123	1.4	44.1
7	61.5	27.0	5.00	16.8	2.5	53.9	0.137	1.4	44.1

Table 4 Range of values for mechanical parameters of the surrounding rock

弹性模量 E/GPa	泊松比μ	峰值黏聚力c/MPa	峰值内摩擦角 φ/(°)	残余黏聚力c_r/ MPa	残余内摩擦角 φ_r/(°)	抗拉强度σ_t/ MPa
10.5~ 16.5	0.24~ 0.28	1.2~ 1.8	44~ 56	0.8~ 1.2	35.2~ 44.1	0.075~ 0.145

Table 5 Sensitivity of surrounding rock deformation to main mechanical parameters

围岩变形	弹性模量E/GPa	泊松比μ	峰值黏聚力c/MPa	峰值内摩擦角φ/(°)	抗拉强度 σ_t/MPa
拱顶沉降	0.884 4	0.401 6	0.069 1	0.098 3	0.006 6
洞周最大位移	0.910 3	0.521 5	0.082 2	0.137 9	0.020 4
围岩内部变形	0.970 7	0.583 6	0.109 3	0.182 1	0.061 8

Table 6 Sensitivity of surrounding rock relaxation to main mechanical parameters

围岩松弛量	峰值黏聚力c/ MPa	残余黏聚力c_r/ MPa	峰值内摩擦角 φ/(°)	残余内摩擦角 φ_r/(°)	临界塑性剪应变ε_P	抗拉强度σ_t/ MPa
平均松弛深度	0.592 5	0.107 4	0.921 4	0.099 0	0.015 8	0.019 1

Table 7 Training and testing samples of parameters to be inverted for cavern surrounding rock

编号	弹性模量 E/GPa	泊松比μ	峰值黏聚力 c/MPa	峰值内摩擦角 φ/(°)	拱顶沉降/ mm	洞周最大位移/ mm	围岩内部变形/ mm	平均松弛深度/m
1	10.5	0.28	1.20	44	4.32	18.87	10.60	1.59
2	13.5	0.25	1.20	47	2.94	14.47	8.05	1.23
3	16.5	0.27	1.20	50	2.63	14.09	6.60	1.21
4	12.0	0.24	1.20	53	3.13	19.06	8.86	1.69
5	15.0	0.26	1.20	56	2.76	15.44	7.20	1.44
6	16.5	0.25	1.35	44	2.40	13.95	6.50	1.05
7	12.0	0.27	1.35	47	3.62	19.43	9.09	1.72
8	15.0	0.24	1.35	50	2.51	15.25	7.09	1.41
9	10.5	0.26	1.35	53	3.93	22.07	10.28	1.80
10	13.5	0.28	1.35	56	3.35	17.36	8.13	1.38
11	15.0	0.27	1.50	44	2.89	15.49	7.26	1.39
12	10.5	0.24	1.50	47	3.58	21.84	10.13	1.75
13	13.5	0.26	1.50	50	3.06	17.15	8.00	1.33
14	16.5	0.28	1.50	53	2.73	14.18	6.65	1.26
15	12.0	0.25	1.50	56	3.29	19.19	8.93	1.67
16	13.5	0.24	1.65	44	2.79	16.96	7.88	1.49
17	16.5	0.26	1.65	47	2.51	14.03	6.54	1.24
18	12.0	0.28	1.65	50	3.76	19.51	9.14	1.74
19	15.0	0.25	1.65	53	2.64	15.34	7.14	1.43
20	10.5	0.27	1.65	56	4.13	22.19	10.38	1.82
21	12.0	0.26	1.80	44	3.45	19.31	9.00	1.70
22	15.0	0.28	1.80	47	3.01	15.60	7.32	1.46
23	10.5	0.25	1.80	50	3.76	21.94	10.20	1.77
24	13.5	0.27	1.80	53	3.21	17.24	8.07	1.36
25	16.5	0.24	1.80	56	2.28	13.84	6.45	1.18

Fig.5 Test results and relative error of evolutionary neural network

Table 8 Comparison between monitored and calculated values of deformation and relaxation parameter of surrounding rock

变形松弛参量	拱顶沉降/ mm	洞周最大位移/mm	围岩内部变形/mm	平均松弛深度/m
现场监测值	3.10	12.80	7.3	1.15
数值计算值	2.82	13.91	6.82	1.22
相对误差/%	9.0	8.7	6.6	6.1

Table 9 Inversion results of mechanical parameters of surrounding rock

弹性模量E/GPa	泊松比μ	峰值黏聚力 c/MPa	峰值内摩擦角 φ/(°)
12.8	0.25	1.3	51.6

Fig.6 Displacement and plastic zone distribution of the surrounding rock of the cavern

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