A combined milling and blasting construction method for tunnels in water-rich sandy dolomite strata

Abstract

A combined milling and blasting construction method for tunnels in water-rich sandy dolomite strata, to effectively reduce the risk of arch collapse and water and mud inrush under the condition of broken surrounding rock, control over- and under-excavation of tunnels, speed up construction progress, and shorten The unit cycle construction time effectively reduces the tunnel construction cost. Including the following steps: pre-construction preparations; ②weak blasting to excavate the core soil of the upper step, the excavator on the upper step removes slag to the position of the middle and lower steps, and then uses the cantilever roadheader to mill and excavate the reserved rock mass of the upper step, to be trimmed to The design outline was implemented in time for the initial support around the upper step; the core soil of the middle step was excavated by weak blasting, the excavator of the middle step removed the slag to the position of the lower step, and then the cantilever roadheader was used to mill and excavate the reserved rock mass and middle step on the left side of the middle step The rock mass on the right side is reserved, and the initial support on the left side of the middle step and the initial support on the right side of the middle step will be implemented in time after being trimmed to the design contour; Initial support on the right side; weak blasting to excavate the inverted arch rock mass, and apply the inverted arch initial support.

Description

technical field [0001] The invention relates to the field of tunnel construction methods, in particular to a milling and blasting combined construction method for tunnels in water-rich sandy dolomite formations. Background technique [0002] With the continuous improvement of my country's national railway network, it is inevitable to build railway tunnels under complex geological conditions in mountainous areas. In particular, when tunnels pass through water-rich dolomite sandy strata, the Frequent changes, dense rock mass before disturbance, and extremely poor self-stability under the erosion of water” and other characteristics, landslides, water inrush and mud gushing often occur during construction, which seriously endanger the safety of tunnel construction. [0003] At present, the drilling and blasting method is still the main method in tunnel construction. The impact of blasting on the surrounding rock and supporting structures is reduced by smooth surface or pre-splitt...

AI Technical Summary

Problems solved by technology

[0007] 1. The space of the pre-cut grooves is narrow, and it is difficult to construct the steel frame, and it is impossible to construct the radial system anchors in time, which affects the bearing capacity of the supporting structure;

[0008] 2. The core soil is constructed by milling and excavation, and the work efficiency is low. However, when blasting is used for excavation, it is easy to cause greater damage to the initial support due to blasting disturbance or mechanical slag discharge;

[0009] 3. If the surrounding rock in front of the face of the tunnel is broken and the groundwater is abundant, construction in the pre-cut groove space will easily cause the surrounding rock of the arch to collapse, and the construction safety risk is high

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