• An auger is used to bore hole on the ground.
• Two types of auger – helical and post hole auger.
WASH BORING SYSTEM
•A piece of metal tube is used to bore hole with depths ranging from 1.50-3.0meters.
•The tube or casing is cleared of the soil sample by chopping bit to the lower portion of the wash pipe inserted inside the tubing or casing. •Water is then used to wash down through the wash pipe by means of a high velocity pump to rinse fragments of soil.
•Similar to process of installing an underground water pump.
HOLLOW STEM AUGER BORING
SYSTEM
•A truck mounted driving rig turns the auger to a depth of more than 60 meters .
•Has a hollow stem where samples of soil can be retrieved.
ROTARYDRILLING
• One of the most efficient and convenient method of soil sample retrieval. • Used for soil structure characterized by high resistant materials such as rocks, clay as well as sand.
• Auger diameter – 60-80mm
PERCUSSION DRILLING
METHOD
• a.k.a. Cable Tool Drilling Method
• Used when boring or auger method is not possible due to difficulty in penetration of soil especially hard soil strata.
PENETROMETER
•A device used to investigate the consistency of cohesive deposit or relative density of cohesionless strata without the necessity of drilling and obtaining samples.
• Static penetration is characterized by consistent and uniform force or pressure application and dynamic penetration when driven into the soil.
•The number of blows to make a penetration of
300mm is regarded as the penetration resistance.
DUTCH CONE PENETRATION METHOD
•A cone is attached to the tip of a rod and protected by a casing. •The cone is pushed by the rod into the ground. •The cone is slightly larger than the pipe in order to minimize friction between the tool and the surrounding soil.
VANE
SHEAR TEST
• The vane device for shear testing of clay soil in place consist of four vertical rectangular blades.
•The vane is pushed into the soil and twisted until the soil is ruptured in a cylindrical form.
•Shear strength is coumputed from the maximum moment needed to rupture the soil and thereby obtaining a soil sample.
