Method for restraining deformation of small-clear-distance tunnel in argillaceous sandstone stratum

Abstract

The invention discloses a method for restraining deformation of a small-clear-distance tunnel in an argillaceous sandstone stratum. The method comprises the steps that 1, a deformation monitoring module is installed, and an arch foot of an upper supporting steel frame is reinforced; 2, a primary supporting structure is reinforced for the first time; 3, middle clamping rock is reinforced; 4, the primary supporting structure is reinforced for the second time; and 5, the primary supporting structure is reinforced for the third time. According to the method, deformation of surrounding rock of the small-clear-distance tunnel is restrained by reinforcing the primary supporting structure, construction operation is easy, and the reinforced primary supporting structure is reliable and stable; and by reinforcing, monitoring and measuring multiple parts of the primary supporting structure, the stability and structural rigidity of the primary supporting structure are enhanced, cracking of the primary supporting structure is avoided, and therefore settlement convergence deformation of the surrounding rock of the tunnel is reduced, reinforcing and stability maintaining in the initial excavation stage of the tunnel are achieved, and the overall stability and construction safety of the tunnel are guaranteed.

Description

technical field [0001] The invention belongs to the field of reinforcement construction of small clear distance tunnels, and in particular relates to a method for suppressing deformation of small clear distance tunnels in argillaceous sandstone formations. Background technique [0002] The small clear distance tunnel refers to the special tunnel layout form in which the thickness of the interlayer rock in the tunnel is less than the minimum clear distance of the separated independent double tunnel. Destruction of the ecological environment and other issues. During construction, the construction is divided into the first hole and the second hole in sequence. Among them, the excavation of the second hole will cause the stress redistribution of the surrounding rock supported by the first hole, and the excavation of the first hole itself will also cause tunnel damage. Stress redistribution in surrounding rock, especially in expansive argillaceous siltstone geological conditions,...

AI Technical Summary

Problems solved by technology

[0002] The small clear distance tunnel refers to the special tunnel layout form in which the thickness of the interlayer rock in the tunnel is less than the minimum clear distance of the separated independent double tunnel. Destruction of the ecological environment and other issues. During construction, the construction is divided into the first hole and the second hole in sequence. Among them, the excavation of the second hole will cause the stress redistribution of the surrounding rock supported by the first hole, and the excavation of the first hole itself will also cause tunnel damage. Stress redistribution in surrounding rock, especially in expansive argillaceous siltstone geological conditions, due to the characteristics of soft rock, fragility, easy softening and disintegration when exposed to water, and loose structure, the self-stability of surrounding rock is poor. The deformation of the surrounding rock in the early stage converges greatly and the unevenness is obvious. The support structure needs to bear the secondary stress distribution of the surrounding rock. A little carelessness may cause damage to the support structure, excessive deformation, and line invasion, etc., and arch replacement construction is required. Arch replacement construction is difficult, risky and costly. Therefore, it is necessary to control the amount of tunnel deformation for the construction of small clear distance tunnels in argillaceous sandstone formations

[0003] The existing tunnel deformation suppression methods mostly use the middle partition method or the three-step seven-step construction method. If the middle partition method is used for construction, when the excavation cross-sectional area of ​​the tunnel with a small clear distance is less than 100㎡, the block area is extremely small, and the large-scale The machine cannot work, resulting in poor operability and slow construction progress; if the three-step seven-step method is used for construction, under the geological conditions of argillaceous sandstone, the settlement and deformation of the surrounding rock at the initial stage of excavation will be large, and the support measures will not be in place. It is very easy to cause cracks in the initial support structure of the tunnel and surface cracks, which will affect the overall stability of the tunnel and lead to landslides

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