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Study on Large Deformation Characteristics and Control Measures of Water-rich Phyllite Rock Tunnels
(1. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 741300; 2. Gansu Highway Traffic Construction Group Co., Ltd.,Lanzhou 741300; 3. Department of Railway Engineering and Civil Engineering, Shandong Polytechnic, Jinan 250104;4. Gansu Shunda Road and Bridge Construction Co., Ltd., Lanzhou 741300)
Abstract Based on the Heimaguan Highway Tunnel in water-rich phyllite rocks, this study delves into the control technology for tunnel rock large deformation. Through analysis of the characteristics and causes of large deformation and failure, it is found that the complex geological tectonism in the tunnel area leads to the development of rock joints in the phyllite, and the migration of mineral components and free oxides in the joints further deteriorate the mechanical properties of the rock mass. Due to the strong sensitivity to water, the phyllite rock softens and disintegrates severely after long-term water immersion, resulting in low surrounding rock strength and susceptibility to large deformations in the tunnel. Field monitoring data analysis shows that the tunnel's large deformations exhibit significant asymmetry, and the deformations worsen after the excavation of the lower heading. Reinforcement measures such as sealing of groundwater, optimization of support parameters, and alternate construction of local double arch have been carried out to deal with the large deformation section in the water-rich phyllite rock tunnel. The results indicate that using the construction technology of discharging and sealing water as well as alternative construction of double-layer arch can effectively control the asymmetric large deformations caused by softening of the phyllite rock by long-term water immersion and it is more convenient and economical.
Abstract：
Based on the Heimaguan Highway Tunnel in water-rich phyllite rocks, this study delves into the control technology for tunnel rock large deformation. Through analysis of the characteristics and causes of large deformation and failure, it is found that the complex geological tectonism in the tunnel area leads to the development of rock joints in the phyllite, and the migration of mineral components and free oxides in the joints further deteriorate the mechanical properties of the rock mass. Due to the strong sensitivity to water, the phyllite rock softens and disintegrates severely after long-term water immersion, resulting in low surrounding rock strength and susceptibility to large deformations in the tunnel. Field monitoring data analysis shows that the tunnel's large deformations exhibit significant asymmetry, and the deformations worsen after the excavation of the lower heading. Reinforcement measures such as sealing of groundwater, optimization of support parameters, and alternate construction of local double arch have been carried out to deal with the large deformation section in the water-rich phyllite rock tunnel. The results indicate that using the construction technology of discharging and sealing water as well as alternative construction of double-layer arch can effectively control the asymmetric large deformations caused by softening of the phyllite rock by long-term water immersion and it is more convenient and economical.
CHANG Weixue1,
2 LIANG Qingguo1 LI Qiwei1 FAN Chuntan1,
3 WEI Jian4
.Study on Large Deformation Characteristics and Control Measures of Water-rich Phyllite Rock Tunnels[J] MODERN TUNNELLING TECHNOLOGY, 2024,V61(3): 236-244
2024, Vol. 61 