A construction method for shock-absorbing protection system of hard rock subway station in medium-hole method blasting excavation

Abstract

The invention discloses a shock absorption protecting system for hard rock subway station excavation through a middle hole method. The shock absorption protecting system for hard rock subway station excavation through the middle hole method comprises polystyrene boards laid on side walls and an inverted arch; the polystyrene boards are provided with concrete layers, and during excavation of neighboring chambers, blasting buffer rock walls as thick as 0.8-1 m are preformed in the side walls and the inverted arch. The invention also discloses a construction method of the shock absorption protecting system for hard rock subway station excavation through the middle hole method comprises digging a middle hole at a depth of 10-15 cm exceeding the side walls of the middle hole and 15-20 cm exceeding the inverted arch of the middle hole; laying the polystyrene boards onto the rock surfaces of the side walls and the inverted arch and setting the concrete layers for leveling to form the isolation buffer structure of a temporary support; mounting the temporary support; after first-layer safe steps meet requirements, preforming 0.8-1.0 m thick rock walls at the top of a second layer and then performing blasting processes; during excavation of a side hole, preforming 0.8-1.0 m thick rock walls in a middle separating wall and then performing blasting processes. By arranging the polystyrene boards and the concrete layers on the side walls and the inverted arch and preforming blasting buffer rock walls during excavation of neighboring chambers, the shock absorption protecting system for hard rock subway station excavation through the middle hole method can reduce damage of shock to the temporary support to the maximum degree and ensures construction safety.

Description

technical field [0001] The invention relates to the field of underground engineering construction, in particular to a construction method for a shock-absorbing protection system of a hard rock subway station in the middle-hole method blasting excavation. Background technique [0002] In the construction of subway stations, when the ground conditions are poor and the cross-section is very large, it is generally designed as a multi-span structure, and the spans are connected by beams and columns. The middle hole method, side hole method, post hole method and hole pile method are generally used. and other construction, the core idea is to change the large section into a small and medium section to improve construction safety. [0003] The construction of the middle hole method is to excavate the middle part (middle hole) first, construct the beam and column structure in the middle hole, and then excavate the two sides (side holes), and gradually transfer the top load of the sid...

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Problems solved by technology

[0005] The purpose of the present invention is to overcome the shortcomings of the existing middle-hole method in the construction of the existing middle-hole method that the damage to the temporary support is relatively serious and the appearance quality of the concrete is poor, and to provide a method for blasting and excavating medium-hard rock by the middle-hole method. Construction method of shock absorbing protection system in subway station

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