In building foundation construction scenarios, different types of foundation soils bring varying impacts to drilling operations, and the reverse circulation drill rig needs to make targeted adjustments to deal with these situations. When facing highly cohesive soil, the mud circulation system of the reverse circulation drill rig plays a role. It delivers mud with moderate viscosity to wrap soil particles around the borehole, reducing the adhesion of mud to the inner wall of the drill pipe and preventing borehole blockage caused by soil caking. At the same time, workers will properly control the drilling speed, giving the mud enough time to carry away crushed soil clods and maintaining smooth drilling.
When encountering sandy soil, the anti-collapse measures of the reverse circulation drill rig are particularly critical. This type of soil has loose particles, and the borehole wall is easy to collapse. At this time, the drill rig will increase the density of the mud, which forms a protective film on the borehole wall to enhance the stability of the wall. In addition, the drill bit of the reverse circulation drill rig adopts a spiral structure. During drilling, it can not only break the sandy soil but also quickly transport the sandy soil to the ground through the spiral blades, reducing the possibility of sand accumulation in the borehole and further lowering the risk of borehole collapse.
If there is a soil layer with interbedded stones in the construction area, the drill bit material and speed adjustment of the reverse circulation drill rig will be the focus. The drill bit will be made of wear-resistant alloy material to cope with the impact and wear of stones. At the same time, workers will reduce the drilling speed and increase the torque, allowing the drill bit to break stones gradually and avoiding drill bit damage or stones getting stuck in the borehole due to excessive speed. The crushed stones will be carried out of the ground by the mud circulation system, ensuring that the borehole can be advanced to the designed depth as planned.