Slope Support Project

Recommended equipment: XDQ100, XDQ70.

https://www.xingdamachinery.com/productdetails?product_id=367

1) The cutting side slope is cleaned, brushed and flattened.

1) After the slope is basically formed, the pick and the pneumatic pick are matched to trim and clean the slope according to the slope rate of the construction drawing.

2) In order to ensure the appearance quality, when the side slope is leveled, the pits and recesses are embedded with concrete or mortar masonry to ensure that the entire slope is consistent. If the smooth blasting and the method of cooperating with a pick and a pneumatic pick are used for construction, the over-excavation workload is small, and sprayed concrete can also be used for repair on site.

3) After the rock slope is light, the sprayed concrete should be sealed in time to prevent the rock from being exposed for a long time and weathering and falling off, changing its original performance and strength.

(2) Installation of construction joints and drain holes

1) The short anchor wall is provided with an expansion joint every 15m, and the expansion joint board adopts the asphalt plank after 50px, and the width of the asphalt plank is 375px.

2) The wall panels are equipped with drain holes, the drain holes are arranged in a plum blossom shape, with a spacing of 2.5m, and a sandless concrete slab filter layer is installed at the inlet of the drain hole.

3) The water-binder ratio is controlled between 0.38—0.46 when pouring the sand-free concrete slab to prevent the cement slurry from sinking and blocking the sand-free concrete slab due to excessive water, so that there is no gap between the sand or gravel and the water seepage effect is lost. The sand-free concrete The contact surface between the slab and the mountain is separated by medium-coarse sand to enhance water permeability. When installing the sand-free concrete slab, the sand-free concrete slab is required to be placed in the short anchor wall panel. It is strictly forbidden to enter the panel to affect the quality.

4) Install a 625px long φ50mm permeable hose at the bottom of the sand-free concrete slab. The inlet end of the permeable hose is fixed on the sand-free concrete slab with medium-coarse sand, and the outlet end is fixed on a steel mesh or a clay seal to avoid The pipe blockage caused by the face-face concrete spraying is removed, and the pipe opening is unblocked after the construction is completed.

(4) Spray the first concrete

1) In order to keep the slope stable and close the rock wall in time, spray a layer of 125px thick concrete immediately after excavation, and dry spray with a PH30 rotor sprayer. The mix ratio is cement: sand: gravel: quick-setting agent = 1:2:1.5:0.03, using ordinary Portland cement C32.5 grade, sand is medium coarse sand, gravel is 10-15mm, water-binder ratio is controlled between 0.40-0.45, concrete dry material mixing adopts a mixer.

2) When spraying, the surface of the concrete is smooth, shiny, the aggregate is evenly distributed, and the amount of rebound is small. S-type circulation method or spiral moving nozzle spraying is adopted. The spray gun should be as vertical as possible to the slope and keep a distance of 1.0-1.5m. After the concrete is finally set (6h), spray water for curing. The curing time is 10-14d.

(5) Drilling

1) After the initial shotcrete reaches 70% strength, perform short anchor drilling operations. The short anchor hole diameter is ≥110mm, the design depth is 6m, 9m, and the hole depth is shorter than the short anchor length 0.15m.

2) Use a down-the-hole drill for drilling operations. The depth of the hole is 15 degrees downwards from the horizontal, and the accuracy of the hole distance and inclination should be ensured.

3) It is strictly forbidden to carry water when drilling to prevent the hole from being too deep to block the hole with waste residue. After drilling, empty it. Use the pneumatic drill high-pressure air to squeeze out the waste. Block the hole, and pay attention to protecting people from hurting people when the waste dregs fly out of the hole.

(6) Install short anchors

1) Short anchors: Φ22mm Grade II steel bars. The corresponding accessories are: positioning brackets welded to the steel bars, screw end rods and end rod nuts welded to the ends of the short anchors; short anchors are 6m and 9m long. Species, the spacing is 1.5m (vertical) × 1.5m (horizontal), 2m (vertical) × 1m (horizontal) rectangular arrangement.

2) Short anchors are transported to the construction site after construction on the processing site, including the welding of screw rods and fixing brackets, end rods and contact butt welding, before placing the short anchors, use high-pressure air to clear the holes, and the rods will occupy the holes. In the middle, because the short anchors are 6-9m long, the steel bars are easily deformed when inserted, which makes it impossible to insert the steel bars. For this reason, three arc-shaped guide ribs (ie brackets) are set on the steel bars in advance every 3-5m ) To ensure the center of the steel bar and facilitate the normal grouting.

3) After the hole is cleared, short anchor nails are installed, and two pipes are inserted at the same time, one is a high-pressure grouting pipe for grouting, and the other is an exhaust pipe, which is used to shoot the air in the coarse hole during grouting to avoid voids. While affecting the quality of short anchor bolts, the grouting pipe is inserted into the bottom of the pipe hole when grouting, and the distance between the exhaust pipe and the grouting pipe is 100-3000px.

(7) Grouting

1) After the installation of the short anchor nail is completed, grouting with M30 cement mortar, the grouting pressure is 0.2-0.4Mpa, and the grouting situation should be grasped at any time during grouting. The grouting is very fast at the beginning, and when the grouting speed is slow, the exhaust pipe will also be exhausted. More to less, this means that the mortar in the hole has been poured to a depth of more than 1250px, and the two pipes are drawn out at the same time. The sub-twitch should be slow and continue grouting to ensure that the depth of the grouting pipe buried in the mortar is maintained at about 1250px.

2) The exhaust volume of the exhaust pipe should be known at all times, and it is strictly forbidden to quickly draw the pipe and the exhaust volume of the exhaust pipe suddenly increases, causing discontinuous mortar filling, broken nails and scrapping.

(8) Construction of hanging nets and anchoring heads

1) After the strength of the cement mortar reaches 50% of the strength indicated on the construction icon, hang a 20×500px Φ8mm steel mesh to make it close to the slope surface, and the steel mesh is connected by welding.

2) At the end of the anchor rod and the steel bar, the 2Φ22 steel bar anchoring head and the anchor bar are welded on both sides. The length of the welding seam is ≥110, so that the steel bar mesh is closely attached to the concrete surface, generating a certain resistance to pull out and forming a whole with the steel bar mesh. .

(9) Spray the second layer of concrete

1) Spray the second layer of concrete following the previous process. C20 concrete was sprayed to a thickness of 125px with the same mixing ratio as the first time. After spraying for 6 hours, it was cured.

2) The sprayed concrete should be strictly controlled in accordance with the mixing ratio determined in the laboratory, and the water-binder ratio should be controlled. When spraying the concrete, the thickness should be maintained, and there should be a certain slope at the overlap to avoid lap joints.

(10) Spray cement mortar

After the completion of the second layer of concrete spraying process, in order to ensure the smooth and beautiful surface of the sprayed layer, a layer of 25px thick M20 cement mortar is finally sprayed on the surface of the sprayed concrete.