The rotary excavation process has the following advantages:
(I) Broad adaptability
In hard soils, due to the limited weight of conventional drilling rigs, it is impossible to apply greater feed pressure to the drill bit. The rotary drilling rig uses a power head device, and the feed force of the rotary rig power head plus the weight of the rotary drilling rig drill rod has strong drilling ability. According to statistics, in the same formation, the hole-forming speed of the rotary drilling rig is 5 to 10 times that of the rotary rig.
(B) good environmental protection
At present, the traditional domestic drilling rigs mostly adopt the form of connected drill pipe and slag extraction bucket. During the drilling process, the mud circulation method is mostly used. The mud plays the role of lubrication, hole wall support, replacement and carrying of slag. With the increasingly strict environmental protection requirements of urban construction, traditional drilling rigs are facing greater crisis. Rotary drilling rigs use power heads. Their working principle is to use short spiral drills or rotary buckets to directly drill soil or gravel using powerful torque. The slag is rotated and excavated, and then quickly lifted out of the hole. Dry construction can be achieved without the need for mud support. Even in the case of special stratums, the mud can only support the hole wall. During drilling, The content of mud is quite low, which greatly reduces the pollution source, improves the construction environment, and reduces the construction cost.
(3) Improve the bearing capacity of cast-in-situ piles
Due to the special hole-forming technology of the rotary drilling rig, it only requires static pressure mud as the wall protection. The mud used is generally configured with bentonite, pyrogenic alkali, cellulose, etc., and no thick mud skin will be formed on the hole wall. In addition, due to the repeated reciprocating up and down of the rotary drilling rig, the hole wall has a high roughness and it is not easy to reduce the diameter. Compared with the traditional bored pile, the bearing capacity of the rotary bored pile is higher.