Three-step mechanical excavation method for large-section soft rock highway tunnel

Abstract

The invention discloses a three-step mechanical excavation method for a large-section soft rock highway tunnel, which relates to the field of highway engineering and comprises the following steps of: excavating an upper step with the height of 5m by adopting a cantilever type heading machine, and carrying out primary support after excavation; a longitudinal channel is excavated after the upper step is excavated by 20 m; meanwhile, a hydraulic olecranon hook is adopted to excavate a middle step, and primary support is conducted after excavation; the height of the middle step is 2.5 to 3.5 m; after supporting of the upper step is completed and the strength of sprayed concrete reaches 70% of the design strength, a hydraulic olecranon hook is adopted for excavation of the lower step, and primary supporting is conducted after excavation; performing inverted arch excavation, supporting and surrounding rock monitoring measurement; and if the surrounding rock is stable, the next cycle of excavation, supporting, inverted arch construction, concrete filling and secondary lining construction is conducted till construction is finished. According to the three-step mechanical excavation method for the large-section soft rock highway tunnel, disturbance to surrounding rocks is small, the relaxation range of the surrounding rocks is small, the construction efficiency is high, and the safety and environment friendliness are far higher than those of excavation through a drilling and blasting method.

Description

technical field [0001] The invention relates to the technical field of highway engineering, in particular to a three-step mechanical excavation method for a large-section soft rock highway tunnel. Background technique [0002] In the field of highway engineering, tunnel excavation is often required. At present, for large-section soft rock tunnels, the three-step seven-step drilling and blasting method is generally used. However, the three-step seven-step drilling and blasting method has many technical defects; there are many excavation procedures, the excavation progress is slow, and the space is small. The rock disturbance is large, the top arch is easy to collapse, and the surrounding rock is easily unstable due to the impact of blasting. The blasting method has a great impact on rock walls in tunnels with small clear distances, and staggered distances and measures are usually taken to strengthen the treatment. The blasting method divides the process into drilling, smoke...

AI Technical Summary

Problems solved by technology

One disadvantage of the three-step seven-step method is that there is no transportation channel, and the upper part of the slag needs to be dumped, and the lower part is loaded with a loader or a dump truck for transportation.

The blasting method has many operators and high safety risks

Images