Shaft boring machine (zen boring machine) is a kind ofrotary drilling machine used for vertical well excavation. This methoduses a large tool that is smaller than the excavation hole, which revolvesaround a shaft and is immersed in the hole to excavate the hole. This kindof tool can reduce the peripheral force concentrated on the hole wall,reducing the pressure on the hole wall and preventing the hole wall fromcollapsing.
The shaft boring machine is composed of a mainframe, a reaming tool, anillumination system, an operation control system and an auxiliary device.The main frame is fixed on the bottom of the well and the reaming tool isused to excavate the well bottom. The illumination system can provideillumination inside the well. The operation control system can control thedepth and speed of the boring tool during the excavation. The auxiliarydevice is used to drive the reaming tool and extend the well bottom.
The shaft boring technique is usually used in the construction ofdewatering wells with a drilling depth of less than 30 meters. Themaximum diameter of the shaft boring machine can be adjusted by 9.5 meters.During the excavation process, the reaming tool is fixed with a series ofaugers, which rotate around the central axis, so that the excavation ofthe well can be carried out from top to bottom. The reaming tool can beadjusted in the well according to the change of the geologicalconditions, which can reduce the material sticking in the hole andimprove the excavation efficiency.
This method is suitable for sands, clayey and silt formations, as wellas rock formations with a hardness of up to 10 Mohs. The advantages ofthis method are that a single machine can dig a big well, the hole wall iswell supported, and the production and cost can be reduced. However, youshould pay attention to the fact that the depth of the excavation islimited, the working environment is harsh, and the operator should payattention to the safety during the process of excavation.
In conclusion, the shaft boring machine is an effective method forexcavating vertical wells. It is suitable for different formations andhas some advantages, such as high production and low cost. However, youshould also pay attention to the limited depth of the excavation and thepoor working environment during the operation. Therefore, safety shouldbe the top priority when using the shaft boring machine.
