Safe and efficient construction method for upper-soft and lower-hard rock mass large-section underground excavation tunnel

Abstract

The invention discloses a safe and efficient construction method for an upper-soft and lower-hard rock mass large-section underground excavated tunnel. A CD construction method is improved under specific stratum conditions. A whole tunnel section is provided with upper steps and lower steps and is divided into four cavities in the left and right, and the construction method comprises the steps that 1, an upper step left pilot tunnel is excavated, then primary support is conducted, and a middle partition wall of the upper step is constructed; 2, an upper step right pilot tunnel is excavated, preliminary bracing is conducted, and the middle partition wall is dismantled; 3, a lower step left pilot tunnel and a left lower inverted arch are excavated, and primary support of the left lower stepand the left lower inverted arch is conducted synchronously; 4, a lower step right pilot tunnel and a lower right inverted arch are excavated, and primary support of the lower right step and the lowerright inverted arch is conducted synchronously; 5, an inverted arch is constructed; and 6, waterproof plates are laid, secondary lining pouring is conducted, and therefore excavation and supporting of the tunnel are completed. The construction method can be suitable for tunnel excavation of a stratum with uneven lithology, especially in a rock body with the soft upper portion and the hard lower portion, and the adaptability of the construction method to stratum changes and the flexibility of construction method conversion can be reflected.

Description

technical field [0001] The invention relates to a safe and high-efficiency construction method that can be used in projects such as highways, railways and subways to pass through large-section submerged tunnels with 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 increasing, and it shows a trend of gradually increasing length, section and span. For the excavation of large-section and super-large-section tunnels, higher construction technology is required, and the construction efficiency should be improved as much as possible under 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-side-wall pilot-pit method. These construction methods have different adaptability to geologic...

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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