Mud rotary drilling is a fast and efficient method of drilling, effective in a wide range of geological formations, including sand, silt, clay, gravel, cobbles, and boulders. Also used for coring bedrock, it is not hindered by the presence of groundwater.
New and seasoned operators find that the Geoprobe® 3126GT makes SPT sampling through mud rotary drilling fast and easy. Once the drill mast is in position, the innovative centerline head side shift eliminates the need to move the drill mast again during drilling operations. Simply slide between rig functions used for SPT through mud rotary, including the GH63 percussion hammer, rotary head, automatic drop hammer, rod grip puller, and winchline. The fast transitions between functions made possible by the 3126GT head side shift and well-designed control panel maximizes drilling efficiency like never before.
Setting up for mud rotary drilling is easy on the 3126GT. Drive a five-foot conductor casing to depth using the GH63 percussion hammer. Without moving the machine, the drill mast is raised to make room for the mud pan. Once the mud pan is in place, extend the drill mast over the conductor casing. Then position outriggers to stabilize the mast.
At this point, the head side shift function has been used to align the rotary head over the casing. Rotate an NWJ drill rod while water is pumped through the rod, sub, and bit to wash cuttings up out of the hole and into the mud pan. Using the control panel, the operator can fine-tune water flow from the pump or activate the available hands-free controls. Once depth is reached, the breakout is used to help break the joint to remove the sub and bit. This makes work safer and easier on the drill crew. Then, shift the rotary head out of the way to use the winchline to pull the drill rod, sub, and bit from the hole.
The SPT sample is then ready to be taken with the hands-free Geoprobe® automatic drop hammer. A Geoprobe® interlocking split spoon sampler is added to the bottom of the NWJ rod string and lowered into the hole. Then, add an ADH drive cap to the top of the rod. Once in place, side shift the drop hammer over to take the SPT sample. With sampling complete, the drop hammer can be side shifted over in order to use the winchline. Using the Geoprobe® spring assisted swivel lift cap, pull the rod string and interlocking split spoon from the hole. Mud rotary drilling and SPT sampling can continue through the conductor casing until the desired depth is reached and all samples are taken. If sampling through drive and wash, the outer casing will continue to be put in place at each depth interval.
In addition to the positioning controls, head side shift, and well-designed control panel, other 3126GT features that make it easy for mud rotary drilling include: 105 inches of head stroke to help clear the hole with tooling when working over a mud pan, rod grip puller and 48,000 pounds of head pull back to retrieve conductor casing from the ground, storage for the drill rods on the side of the unit that makes for easy access, and the ability to use the rear blade of the machine to transport the water tank into place
New or seasoned operators can easily adapt to using the 3126GT for fast SPT sampling through mud rotary drilling. This next-generation machine is engineered specifically to increase geotechnical field efficiency. With the Geoprobe® 3126GT, you can drill more and make more.
For more information on the 3126GT, visit our website or call us at 785-825-1842.