Safe and efficient construction method of large-section undercut tunnel in upper soft and lower hard rock mass

Abstract

The invention discloses a safe and efficient construction method for large-section undercut tunnels of upper soft and lower hard rock mass, which is an improvement to the CD construction method under specific stratum conditions. The entire tunnel section is divided into four chambers, the upper and lower steps, left and right. The construction steps are as follows: 1. Excavate the left pilot hole of the upper step, and then carry out initial support, and apply the middle wall of the upper step; 2. Excavate the right side of the upper step. 3. Excavate the left guide hole and the lower left invert of the lower step, and simultaneously carry out the initial support of the lower left step and the lower left invert; 4. Excavate the right pilot hole of the lower step and For the lower right inverted arch, the initial support of the lower right step and the lower right inverted arch is carried out simultaneously; 5. The inverted arch is applied; The invention can be applied to tunnel excavation of uneven lithologic stratum, especially in rock mass with upper soft and lower hard, and can reflect the adaptability of the construction method to stratum changes and the flexibility of construction method conversion.

Description

technical field [0001] The invention relates to a safe and efficient construction method which can be used in highway, railway, subway and other projects to dig tunnels with large sections through upper soft and lower hard rock masses. Background technique [0002] With the rapid development of my country's transportation industry, the construction scale of traffic tunnels such as highways, railways and municipal tunnels is getting larger and larger, and it shows a trend of gradually increasing length, section and span. For the excavation of large-section and super-large-section tunnels, the required construction technology is high, and the construction efficiency should be improved as much as possible on the premise of ensuring construction safety. [0003] At present, the main excavation methods for large-section tunnels include the CD method, the CRD method, and the double-sided pilot pit method. These construction methods have different adaptability to projects with uni...

AI Technical Summary

Problems solved by technology

However, for the construction of underground excavation tunnels with large lithology changes in the tunnel section, when the classic CD method, CRD method and double-side pilot pit method are adopted, the method is suitable for the layer with poor lithology. Uneconomical and unreasonable situations such as super-strong support, small step distance, and small block division occur in layers with better lithology

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