Abstract:

The building blocks were drilled by the triangle-shaped probe unit with different rotational speed and penetration speed on the rotary penetration apparatus in the laboratory in order to study the influence of cutting action and penetration mode on penetration resistance. The data of axial pressure and torque as well as depth of penetration were collected during the test. The typical S-shaped result curve between axial pressure, torque and the depth of penetration is composed of three parts, which are starting, climbing and steady part. The conclusion was reached by analyzing the laboratory test data that the different penetration methods from CPT enables the probe unit to be pressed in soft rock or hard soil with available mechanical equipment. Theoretical analysis and laboratory tests indicate that the way of probe unit with cutting edge is rotated during being pushing in is an efficient measure for probe unit to go smoothly through the harder strata such as hard loess, soft rock and frozen soil.

Key words: geotechnical engineering, engineering exploration, penetration test