Which formations are self-drilling bolts suitable for?
by Simone S. sinorockcoGenerally speaking, the self-drilling bolt is suitable for the stratum, the bolt retaining wall, and the soil nail wall.
For anchoring technologies that require
drilling operations, drilling often becomes the most critical process and
directly affects the bearing capacity of the bolt. Drilling in relatively loose
and groundwater-affected strata, the phenomenon of hole collapse is common,
requiring casing follow-up to increase the difficulty and cost of construction.
The casing improves the drilling progress, but has an adverse effect on the
bond between the mortar and the hole wall. After the loose formation and the
rock formation with many pores and open cracks are formed, high-pressure
grouting can compensate for the geotechnical defects. In this case, the
consistency of the grout needs to be adjusted properly so that the mortar fills
the cracks to ensure the quality of the bolt.
Self-drilling bolts are most suitable for
pebble and boulder formations. After drilling, grouting can effectively
reinforce the disturbed part of the rock and soil around the borehole, and
expand the diameter of the anchor. If there is a small amount of water seepage
during the drilling process, it will also be It can be done by blowing dry
cement powder into the hole with high pressure air. Form temporary retaining
walls around boreholes to reduce hole collapse.
At present, most of the anchor rods
(including soil nails) and pre-stressed anchor cables are manufactured on site,
and their production methods and processes directly affect their quality. Rods
- grouting and compensation grouting – pre-stressing - fixing and end treatment.
The pre-stressed anchor cable is composed of multiple bundles of steel strands.
The application of pre-stress requires special equipment, and the construction
quality varies greatly, while the complete set of self-drilling anchor rods is
factory-produced, which reduces the need for anchor rod production and anchor
rod installation. This process can increase the bearing capacity by 25% only by
tightening the bolts by applying pre-stress, with reliable quality and improved
work efficiency.
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Created on Apr 6th 2022 21:03. Viewed 183 times.