Spaced secondary arch frame and long anchor cable lock foot composite construction method for supersoft rock tunnel

Abstract

The invention discloses a spaced secondary arch frame and long anchor cable lock foot composite construction method for a supersoft rock tunnel, and relates to the technical field of tunnel construction protection. The method comprises: performing construction by a three-step method, wherein the excavated reserved settlement deformation quantity is 500 mm, and advanced small pipes are inserted inthe boundaries of the two side edges and grouting is conducted before middle and lower steps are excavated; a temporary inverted arch primary support is applied after excavation; a grid arch frame isarranged at an interval of 6.0 m; after the two sides of the tunnel are punched by an anchor cable machine, the anchor cable is mounted with 600 mm reserved; grouting is conducted by sulphate aluminium cement, a prestressing force of 3 to 5 tons is applied after solidification for 2 hours, the adjacent two anchor cables are locked by three pairs of anchor cable clamps and are sprayed smoothly withconcrete; and secondary lining is applied by a double-layer reinforced concrete structure to complete construction. On the basis of the first primary support, a composite method of the spaced secondary arch frame and the long anchor cable lock foot is adopted, so that clearance-intrusion, even landslide accident, caused by big deformation of the primary support is avoided, and safety risk is controlled.

Description

technical field [0001] The invention relates to the technical field of tunnel construction protection, in particular to a composite construction method with long anchor cables and locking feet for a tunnel in an extra-soft rock stratum with interval secondary arch frames. Background technique [0002] A high-speed railway double-track tunnel is located in the Jingshan Mountains, which is a structurally denuded low-mountain landform area. The tunnel body passes through the sandy shale of the Xintan Formation (S1x). The tunnel site area is located at the northern edge of the first-order tectonic unit of the Yangtze quasi-platform, within the Shennongjia-Jingmen platform fold belt of the Upper Yangtze continental block fold belt. According to the records of local county annals, earthquakes of magnitude 4.8 or so occurred many times in the area. People felt the ground shaking, their houses were about to collapse, and they fled in panic. watt. The main types of groundwater are...

AI Technical Summary

Problems solved by technology

[0004] The existing scheme adopts the three-step method + temporary inverted arch, and the secondary lining adopts a double-layer reinforced concrete structure, and the deformation amount of 800-1100mm is reserved, and large extrusion deformation occurs, especially on the left side of the line and the top primary branch encroachment limit. Leading to multiple landslides, repeated rework and arch replacement, slow construction speed, sudden increase in construction costs, and extremely high safety risks in landslide accidents, resulting in deduction of credit points for the safety and quality of the construction unit by the owner, which greatly affected the external image of the company

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