Support Of The Roadway On The Top Plate Of Easily Weathered Rock Layer

For the roadway of the top plate of easy weathering rock layer, it can adopt the support method of anchor rod (cable) combination support mainly, supplemented by spraying slurry surface protection, and spray a thin layer of concrete on the wall of the peripheral rock of the roadway in a timely manner after the construction of the anchor support, which can isolate the air and prevent the weathering of the peripheral rock.

After the resin anchoring agent meets water, the anchoring performance decreases sharply, and the anchoring effect between the anchor and the drilling wall is extremely poor, which will directly affect the quality of support. The following methods can be adopted when adopting anchor support for the roadway in the section of roof drenching. However, no matter which method is used, the monitoring of the support quality must be strengthened.

Choose reasonable anchoring depth:

 after the surrounding rock of the roadway meets with water, the design of anchor support should be modified in time, and if possible, increase the depth of drilling holes, lengthen the length of anchor rods, extend the anchoring section to the depth of drilling holes, and avoid the rock layer in the water section. When sending resin anchoring agent into the borehole, it must be stirred only after the anchoring agent exceeds the rock layer of the water outlet section. If the length of the anchor is insufficient, the original anchor can be replaced by an extension anchor or an anchor cable group.

Sealing: 

Use overtopping grouting techniques to close the outflow fissure and seal the source of the shower head water. Poly-saddle grease pressure injection process and anchor injection support technology can be used. Deep hole grouting is preferred for the poly-saddle grease pressure injection method. For anchor injection support, high water materials, water glass and cement slurry can be used, and single or two-fluid slurry system is adopted.

Water conduction: Under the premise of investigating clearly the source and flow direction of the drench head water, drill water conduction holes around the drill holes to divert the water flow into the anchor drill holes, cut off the water source of the drill holes or reduce the amount of drench head water in the drill holes, and improve the anchoring effect. After completing the construction of the anchor, the water-conducting holes should be closed.

Change the anchoring method:

 If it is impossible to avoid the drenching head water section in the borehole or block the source of water outlet, the anchoring method must be changed, which can be adopted as mortar full-length anchoring or cement anchoring agent full-length anchoring.

Practice has proved that anchor support has other support incomparable superiority, in special geological conditions, according to the specific geological conditions or nature of the tunnel surrounding rock to optimize the anchor support design or program, can play a multiplier effect.