Foundation piling method for limestone stratum

Limestone is mostly found in karst terrain, mainly distributed in Guangxi, Guangdong, Yunnan, Guizhou, Sichuan, Chongqing and other provinces in China. It is a kind of sedimentary rock with average hardness.

According to the experience of our previous customer’s construction projects, the uniaxial compressive strength of common medium-weathered limestone can be 30~50Mpa. The hardness of ordinary limestone with higher purity can reach 60~80Mpa. Guangzhou and Shenzhen are the hard rock clusters in the area,where limestone contains quartz content, the hardest strength could reach to 80~90Mpa. Limestone with ordinary hardness can be drilled easily by Baorui barrel core with bullet teeth. For limestone with high hardness and high quartz content, it is recommended to use a roller bits core barrel.

      

Drilling limestone with a core barrel with bullet teeth requires certain skills and operating methods. Different construction techniques are used according to different strata. Limestone in some places should not be added clean water into the boredhole. For example, in some projects in Guangxi province, China, the limestone becomes powder after being drilled. It would be little bit sticky when exposed to water, and paste and slip. In the past,limestone in some projects in some places in Guangzhou was relatively hard and had a high quartz content. At this time, water can be added to cool the drill bit to avoid the wear of the drill bit caused by high temperature grinding.

One of the more complicated cases of limestone is to encounter caves and inclined rocks. When encountering a karst cave, the drilling speed should be slowed down, and the actual situation of the karst cave should be investigated before proceeding, so as to avoid the phenomenon of partial holes caused by excessively fast drilling. Inclined rock can be drilled by hanging the drill bit and slowly leveled.

 

In addition, according to the size of the cave, the drill bit should be lengthened appropriately. If the cave is too deep to be dealt with by lengthening the drill bit, a full casing is required.

The strata encountered in each place and project are different. If you have encountered a limestone project, you are welcome to discuss and supplement with us