The soil samples are required to be undisturbed in scientific drilling of Hemudu - Tianluoshan site in Ningbo. Due to the special strata lithology in Ninbo area, it is difficult to meet the requirements with the traditional thick-wall and thin-wall soil samplers. In this case, a new type double-tube core barrel is developed, and the mud technology is also improved. The application shows that the core recovery has been improved with high quality soil and rock samples, the disturbance on undisturbed soil are largely decreased. This new type double-tube core drilling tool, with PVC inner tube and one-way valve, large water outlet and proud exposure bit, has advantages of high efficiency, high performance price ratio and good operability.
Exploration Engineering：Rock ＆ Soil Drilling and Tunneling
double-tube core barrel