1. Arm guards
The mud made of bentonite has good viscosity, so in the trenchless construction, the hollow wall formed by the mud made of bentonite protects the surrounding hole wall in time to prevent moisture from collapsing the hole wall, so the viscosity of good mud bentonite is very good, it is easy to stick with the hole wall and quickly form a protective film, prevent the water from washing the hole wall, and play a very key role in preventing collapse.
2. with chips
In the process of trenchless construction, through the drilling of the drill bit, there will be a lot of crushed stone and fine sand, and it is very important to discharge the crushed stone chips out of the construction hole in time. The mud made of bentonite has good suspension and can bring the debris generated during the construction process out of the construction hole, so that the trenchless can proceed smoothly.
In trenchless construction, drill bit construction will encounter different geology at the same time, some of which are relatively hard such as stone layers and gravel. In this sublayer construction, the wear on the drill bit is very serious. At the same time, the mud made of bentonite has a good lubrication effect, which can lubricate the drill bit during construction and dissipate heat at the same time. This increases the service life of the drill bit and ensures the smooth development of the project.
The choice of trenchless bentonite should first be based on the nature of the project, and the requirements of different projects are different. This can be simply divided into horizontal trenchless and vertical trenchless. Horizontal drilling and drawing pipes, pipe jacking and shield machines belong to horizontal construction; Oil drilling and geological exploration belong to vertical trenchless exploration. These two non-driving methods have very different requirements for bentonite.
The higher the viscosity required by horizontal non-open use of bentonite, the better it is to use. Generally, the viscosity (600 rpm viscometer reading) is selected above 40. If the construction site belongs to a pure sand layer, it is best to choose a viscosity of more than 60, and the ratio of bentonite and water is not less than 5%. Here is a recommendation about the mud soil produced in Liaoning and the mud soil produced in Inner Mongolia. High viscosity, good use effect.
Vertical non-driven non-driven bentonite, the viscosity is generally about 35. It is best to be the viscosity of bentonite itself, without adding tackifiers. Because the tackifier increases in depth during vertical drilling, the temperature will lose its effect after exceeding 300 degrees Celsius. At the same time, it has a certain destructive effect on the drill bit. Therefore, trenchless bentonite made from high-quality bentonite raw ore should be selected.
In short, the choice of trenchless bentonite should be determined according to the actual situation of the construction site. Also consider the cost of use.