Advanced hole-forming method of sand gravel boulder layer

Abstract

The invention provides an advanced hole-forming method of a sand gravel boulder layer, comprising the following steps of: during construction, welding a preserved orifice pipe on a former hinged grille according to the design; after spraying concrete on the former hinged grille, splicing a guide tail type heavy pneumatic drill on steps of a tunnel and then mounting a self-advancing hollow groutedbolt on a drilling machine after the splicing is finished; starting the drilling machine and adjusting the height and the angle of the guide tail type heavy pneumatic drill according to the preservedposition; and after all preparations are finished, starting drilling, separating the self-advancing hollow grouted bolt from the guide tail type heavy pneumatic drill after the drilling depth reachesthe requirement and forming a hole. The advanced hole forming method provided by the invention has the characteristic of great impact and drill rod rotating torque and can be used for respectively adjusting the impact energy, the drill rod rotating speed and the torque; the drilling speed is high, thus one hole can be formed within about 2 minutes after the mounting is in place; and the advanced hole forming method ensures that the equipment used in the method has light weight, high mounting in-place and displacing speed, reasonable overall dimension and small occupied space and is not easy to cause the phenomenon of clamping the drill rod in the sand gravel layer and is low in cost and especially suitable for narrow operation places in the pit.

Description

technical field

[0001] The invention relates to the "pipe advance" part in the "eighteen characters" guideline of the shallow buried underground excavation method used in the construction process of urban tunnels, and is a method for solving the problem of advanced hole formation and support in sand, pebble and boulder layers. Background technique

[0002] The safety of urban tunnel construction is the most important. Safety includes engineering safety and personal safety. The grouting of small conduits in advance (or called short-tube sheds of steel pipes) is the key to the weak surrounding rocks with poor self-stability in underground projects. In the soil body in front of the top, according to a certain spacing, elevation angle and length, after drilling, arrange small advance pipes of Φ32-42mm, and then perform grouting in the pipes to strengthen the soil body. Such as figure 1 shown. After the underground project is excavated forward, the stability of the surrounding ...

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