Pre-reinforcement and excavation construction method for tunnel entrance segment of loess tunnel passing through slip mass

Abstract

The invention discloses a pre-reinforcement and excavation construction method for a tunnel entrance segment of a loess tunnel passing through a slip mass. The method comprises the following steps offirstly, tunnel body soil layer pre-reinforcement, secondly, tunnel entrance construction of the tunnel, thirdly, excavation and preliminary bracing construction of the reinforced tunnel segment, andfourthly, excavation and preliminary bracing construction of the rear tunnel segment. By means of the method, design is reasonable, construction is simple and convenient, and the use effect is good; before excavation, cemented soil stirring piles are adopted for carrying out reinforcement treatment on the loess stratum of the construction area where the tunnel entrance segment of the tunnel is located in advance, the reinforcement length and reinforcement depth are effectively limited, loose soil of the tunnel body of the tunnel is solidified in advance, it is ensured that the construction process of the tunnel entrance segment of the tunnel passing through the slip mass is safe and reliable, and the structure of the tunnel entrance segment, formed through construction, of the tunnel is stable; and meanwhile, a three-step excavation method is adopted for excavating the tunnel entrance segment of the tunnel, it can be ensured that the excavation process of the tunnel entrance segment ofthe tunnel passing through the slip mass is safe and reliable, and the influence on stability of soil layers around the tunnel is small.

Description

technical field [0001] The invention belongs to the technical field of tunnel construction, and in particular relates to a construction method for pre-reinforcement and excavation of an entrance section of a loess tunnel passing through a landslide body. Background technique [0002] Loess refers to sediments of yellow silt transported by wind during the Quaternary period in the geological era. Loess collapsibility coefficient (also called collapsibility coefficient) is a mechanical parameter to evaluate the collapsibility of loess. Under a certain pressure, loess collapsibility coefficient refers to the ratio of the difference between the height of the soil sample before and after soaking in water and the original height of the soil sample. The collapsibility coefficient of loess is an important index to evaluate the collapsibility of loess, which can be directly measured by experiment. According to the different collapsibility coefficient of loess, loess can be divided in...

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Problems solved by technology

[0006] The construction of the entrance section of the loess tunnel passing through the landslide is very difficult, especially when the entrance section of the tunnel is located in the front of the landslide, the construction difficulty is even greater. After analysis, the main problems are as follows: Inducing the sliding of the landslide body can easily bring safety hazards and interference to the tunnel construction; second, the tunnel entrance (ie, the tunnel entrance) is located at the front edge (ie, the front) of the landslide body, and the infiltration of surface water makes the water content of the new loess higher , the slope of the tunnel entrance and the excavation of the open tunnel cannot guarantee its stability, and landslides are extremely prone to occur; third, when the tunnel dark tunnel passes through the landslide body, it is easy to cause disturbance to the landslide body during the excavation operation, so that the tunnel body is in contact with the landslide Under the interaction of different bodies, dislocation will be generated, which will lead to the destruction of the tunnel structure; fourthly, after the excavation of the tunnel body, the water on both sides of the tunnel body will flow to the tunnel body for discharge. shift

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