Deformation and Failure Characteristics of Deep-buried Water Diversion Tunnel Crossing Active Fault Zone and Corresponding Adaptive Measures

doi:10.11988/ckyyb.20230935

Abstract

Abstract:

The safety of the tunnel traversing an active fault is a critical issue for the deep-buried long tunnel crossing the Tongcheng River in the Yangtze-to-Hanjiang River Diversion Project. This study addresses this challenge by employing an analysis of the geostress field and numerical simulation methods.Specifically,it examines the lining’s response in scenarios where adaptive structures are not utilized, estimates the design parameters for hinges, and verifies the lining’s behavior under these hinge parameters. Findings reveal that: 1) The angle between the horizontal principal stress and the tunnel axis is approximately 35°. The horizontal stress component along the tunnel axis is about 20 MPa, while the horizontal stress component perpendicular to the axis is around 21 MPa. The vertical stress component is approximately 18 MPa. 2) Without any fault mitigation measures,the tunnel’s relative deformation primarily exhibits convergence between the vault and floor. This convergence is most pronounced within the fault zone. The maximum principal stress values in the vault and floor occur in the fault zone and its affected area, with most of the lining in these regions experiencing damage. 3) Using the proposed method for estimating tunnel hinge design parameters, a reinforcement section length of 6 meters and a hinge section width of 2-4 cm are initially suggested. Following sensitivity analysis of these parameters, it is recommended that the reinforcement section length remains 6 meters, while the hinge section width is set to 5 cm. 4) When the tunnel is reinforced according to the proposed hinge structure parameters, the design effectively reduces the tension experienced by the entire lining in the fault zone. Under hinge design conditions, there is a significant decrease in relative deformation, stress levels, and lining damage. This demonstrates that the hinge structure enhances the tunnel’s resistance to fault-related issues.

Key words: long-distance water diversion project, water diversion tunnel, active fault, rupture response, hinged lining

CLC Number:

TV223.1岩石性质及其测定

ZHANG Guo-qiang, CUI Zhen, YAN Tian-you, ZHANG Mao-chu, LI Jian-he. Deformation and Failure Characteristics of Deep-buried Water Diversion Tunnel Crossing Active Fault Zone and Corresponding Adaptive Measures[J]. Journal of Changjiang River Scientific Research Institute, 2025, 42(1): 152-161.

Figures/Tables 20

Fig.1 Satellite image interpretation map of intersection point of diversion tunnel line and Tongcheng River fault

Fig.2 Fitting results of geostress of Tongcheng River fault

Table 1 Geostress characteristics of local borehole section of Tongcheng River fault zone

桩号	埋深/ m	隧洞轴线方位角/ (°)	大主应力方位角/ (°)	大主应力与隧洞轴线夹角/ (°)	主应力/MPa
桩号	埋深/ m	隧洞轴线方位角/ (°)	大主应力方位角/ (°)	大主应力与隧洞轴线夹角/ (°)	大水平主应力	小水平主应力	竖直应力
K96+709— K96+778	1 076.4~ 1 129.2	15	340	35	22.77~ 23.89	17.39~ 18.25	17.93~ 18.81

Fig.3 Relationship between geostress field in fracture area and tunnel axis

Fig.4 S-type and linear-type fault displacement pattern curves

Fig.5 Three-dimensional analysis model of tunnel crossing Tongcheng River fault

Table 2 Suggested values of physical and mechanical parameters of surrounding rock of tunnel crossing Tongcheng River fault

地层	围岩等级	密度/ (kg·m^-3)	抗压强度/ MPa	弹性模量/ GPa	泊松比	抗拉强度/ MPa	摩擦角/ (°)	内聚力/ MPa
S₃s	Ⅲ	2.65×10³	80	7.0	0.28	1.0	45	1.0
S₁ln	IV	2.65×10³	25	4.0	0.30	0.7	35	0.7
影响带	IV₂	2.5×10³	10	1.2	0.33	0.5	30	0.5
断裂带	Ⅴ	2.4×10³	8	1.0	0.35	0.3	24	0.3

Fig.6 Tunnel lining response under the condition of 20 cm dislocation

Fig.7 Displacement curves at different positions of tunnel under different fault values

Fig.8 Longitudinal stress curves at different positions of the tunnel under different fault values

Fig.9 Service status of tunnel lining under different fault values

Fig.10 Schematic diagram for calculating relative angle between segments

Fig.11 Tunnel lining response under the condition of 20cm dislocation in the presence of hinged structure

Fig.12 Displacement curves of tunnel in the presence of hinged structure under different fault values

Fig.13 Maximum longitudinal stress curves of tunnel under different fault values

Fig.14 Service status of tunnel lining under different fault values

Fig.15 Displacement curves of tunnel vault with or without hinged structure

Fig.16 Relative deformations between tunnel vault and floor with or without hinged structure

Fig.17 Longitudinal stress curves of tunnel vault with or without hinged structure

Fig.18 Lining volumes of different states with or without hinged structure

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