In order to investigate the change law of stress and strain in the deep surrounding rock and the range of loosening circle during the construction of deep buried soft rock tunnel, indoor modeling test was carried out. The independently designed three-way synchronous loading model box was used to investigate the deformation and stress law of the surrounding rock during the tunnel excavation and support process, and then analyze the range of the loosening circle by installing the strain flower and pre-buried soil pressure box. The results show that the surrounding rock pressure at the monitoring section is released in advance when the tunnel is not excavated to the monitoring section; when the upper step is excavated past the monitoring section, the pressure at the arch top and arch shoulder tends to be stable, while the pressure at the arch waist continues to release; when the lower step is excavated past the monitoring section, the pressure of the surrounding rock at different locations in the monitoring section is stable, which indicates that after the excavation and support of the surrounding rock in front is completed, the construction of the surrounding rock in the back has very little effect on the surrounding rock in the front, and the surrounding rock at the back has very little effect on the surrounding rock in the front. The pressure release of surrounding rock is a process from fast to slow and finally tends to be stable. According to the test results, the loosening circle of the arch top, arch shoulder and arch waist is roughly in the range of 70~120 mm, and the radius of the loosening circle of the arch top, arch shoulder and arch waist is 96.7 mm, 83.3 mm and 106.7 mm respectively, which is close to the theoretical calculation results after using the function fitting. According to the similarity ratio, the actual loosening circle size of the three positions is 4.8m, 4.2 m and 5.3 m, which are about 0.43, 0.38 and 0.48 times the diameter of the hole, respectively. This study provides theoretical and technical references for taking reasonable support measures in advance in deep buried soft rock tunnel construction.
Li Qiuling
,
Liu Yang
,
Yang Huizong
,
Zhang Jianjing
,
Pan Hu
. Model Test Study on Stress Release Mechanism of Deep Buried Soft Rock Tunnel Excavation[J]. Chinese Journal of Underground Space and Engineering, 2024
, 20(S2)
: 722
-731
.
DOI: 10.20174/j.JUSE.2024.S2.24
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