Our drilling platform produces quality performances and efficiencies unique in the world’s construction markets.
TEI rock drills are working hard at soil nail and micropile jobsites worldwide. TEI rock drilling equipment produces quality performances and efficiencies unique in today’s construction and mining markets. Our drilling platform incorporates innovative TEI technology with the most rugged soil and rock drilling components. And TEI’s double swivel action easily accommodates hard to reach high, low and tight drilling positions.
Hollow Bar Soil Nailing
Hollow bar soil nails are ideal for vertical and horizontal applications in any soil environment, but the installation process is best suited for unstable ground conditions. The injection of grout through the hollow bar during installation improves the integrity of the surrounding soil and reduces the overall project time and cost.
Hollow bar installation provides cost-efficient stabilization for a myriad of geotechnical problems. The equipment necessary to install hollow bars is relatively minimal. You only need a TEI drilling platform, portable grout plant, hollow bars and the appropriate hardware.
Hollow Bar Installation Process
Recommended hollow bar sizes are determined in the engineering design. These unique bars are continuously threaded to allow cutting and coupling at any length. Hollow bars can also be cut to short lengths for use in height limited jobs and with small drill rigs. There are many types of bits available for use with hollow bars. From soft clay to hard rock, there is a bit designed to assure penetration of hollow bars in any drilling condition.
The grout plant is as important as the drilling platform. Grout flushing cuts into the soil as much or more than the drill bit. The permeation of grout improves the surrounding soil and strengthens the hollow bar system to provide a clear advantage over other ground reinforcement techniques. A high shear mixer is required for the installation of hollow bars. It is critical that the grout be mixed properly and all cement platelets are hydrated.
A constant flow of grout must be supplied to the drill bit. Pump pressure of 100 bar is recommended for the installation of hollow bars. This high pressure penetrates the soil and prevents the bit from plugging. Only clean potable water and prescribed cement ratios should be used to produce the thin drilling grout and the thick structural grout.
Start the flow of thin drilling grout and begin the hole. Thin grout will permeate the surrounding soil and act as an efficient drilling fluid. Watch constantly for grout returns. A co-worker should use a shovel to clear the top of the hole of drill cuttings and excess grout. If grout return stops, discontinue drilling and work the hole until the grout returns to the surface.
Before adding a new hollow bar, plunge the hole 2 to 3 times to clear the hole and then set your next hollow bar into the drill feed. When the hole is finished to the engineered depth, stop advancing and switch to the final grout mix. Thick structural grout is used to complete the installation. Plunge the bars 3 to 5 times or until the thick grout returns clean to the surface.