1. Construction overview of rotary drilling rig
A rotary drilling rig is a piling machine used for drilling holes in construction foundation engineering. It has the advantages of fast construction speed, good hole quality, small environmental pollution, flexible and convenient operation, high safety performance and strong applicability. It has become a drilling machine. Rotary drilling rig is the main hole-forming equipment for the construction of bored pile. It is a highly integrated pile foundation construction machinery. It adopts integrated design, crawler 360° rotary chassis and mast type drill pipe, generally for the full hydraulic system. Special barrel drill bits, without the need to connect long drill rods, and directly extract soil and slag. When drilling the hole, grouting to keep the mud height in the hole, which can greatly shorten the hole formation time. With automatic verticality control and automatic return control, to ensure the verticality and position of the hole. The bucket drill has little disturbance to the hole wall during lifting. There are overflow holes around the drill, overflow the mud to protect the wall.
2. Rock breaking
At present, there are three main methods of rock crushing in buildings: impact rock crushing, grinding rock crushing and shear rock.
Impact of broken rock: according to the theoretical analysis, only when the pressure acting on the rock exceeds 30%~50% of the rock uniaxial compressive strength limit, the rock will be successfully broken up. Therefore, multiple shocks between the drill tool and the rock can cause the rock to rupture and reduce its strength before the pressure reaches the fracture strength limit of the rock. When the rock strength is reduced to a certain extent, the rock can be broken. The current commonly used equipment is the impact hammer.
Grinding rock: under a very small pressure load, using the friction generated by the rotating drill bit in contact with the rock, to break the rock (this method is actually a grinding action). In this method, the rock crushing speed is slow, the rock crushing particles are fine, and the drilling tool is seriously worn. At present, the commonly used equipment on the market is the positive (reverse) cycle drilling rig.
Shear rock: According to the Cullen-Navy criterion, the shear strength limit of the rock is only about 10% of the compressive strength limit, so the shear method is a good way to break the rock. For the construction equipment with rotary drilling as the main method, if the pressure on the drill gear is applied during the drilling, the drill gear teeth can be cut into the rock, and then the rock can be cut and broken under the action of rotating torque.
Gookma Technology Industry Company Limited is a hi-tech enterprise and a leading manufacturer of rotary drilling rig, concrete mixer and concrete pump in China. You are welcome to contact Gookma for further inquiry!
Post time: Apr-08-2024
