Introduction: Slope anchor support is a reinforcement and stabilization technique widely used in surface engineering projects, including slopes, deep rock and soil excavations, as well as underground tunnel constructions such as tunnels and mining operations. Today, we have summarized the key points of its construction for your reference. Let’s explore them together.
Main Structural Forms of Slope Support
Gravity Wall
A gravity retaining wall relies on its own weight to resist soil pressure and maintain stability. It is commonly used in China due to its advantages of utilizing local materials, ease of construction, and cost-effectiveness. Gravity retaining walls are widely applied in railway, highway, water conservancy, harbor, mining, and other engineering projects.
Counterfort Retaining Wall
Counterfort retaining walls are reinforced concrete thin-walled structures known for their simple and convenient construction, slim wall sections, and lightweight design. These walls fully utilize the strength of materials and adapt well to foundations with low bearing capacity. They are especially suitable for areas lacking stone materials and regions prone to earthquakes. Typically, counterfort walls are used in higher fill sections to stabilize embankments, reducing earthwork volume and land usage.
Lattice Anchor Rod Retaining Wall Support
This slope reinforcement method uses cast-in-place concrete beams and columns arranged in a lattice framework, secured by anchor rods. Vegetation can be planted within this lattice, promoting slope stabilization, vegetation restoration, improving greenery rates, and enhancing environmental aesthetics. The technique benefits from a short construction period, favorable construction conditions, effective results, and an attractive appearance, making it popular in urban slope projects.
Shotcrete and Rock Bolting
Anchor spray support combines anchor rods, sprayed concrete, and surrounding rock to form a load-bearing structure. This method effectively restricts the deformation of surrounding rock, adjusts stress distribution, and prevents rock looseness or collapse. It is often used as temporary support during construction and, in some cases, may serve as permanent support or lining.
Slope Ratio Method
This support approach achieves slope stability by controlling slope height and angle, eliminating the need for fully assembled structural reinforcements.
Construction Precautions
1. Slope Excavation
Excavation must strictly adhere to specific design requirements. For high slopes involving anchoring engineering, excavation should proceed step-by-step from top to bottom. Upper slope anchoring must be fully implemented and reinforced—using effective temporary or pre-reinforcement measures as needed—before excavating lower slope soil and rock. Reinforcement should continue progressively until all protective work is complete to ensure slope stability and structural safety.
2. Masonry
Masonry mortar must meet the specified grade, be fully applied, and comply with relevant construction standards. Block materials should be of uniform quality, sized according to specifications, and composed of sound, unweathered, and durable stones.
3. Drainage
Surface interception and drainage ditches must be installed before soil and rock excavation on road cut slopes. These help reduce the impact of surface water, preventing erosion and infiltration into the slope body.
4. Hanging Net Anchoring
(1) Slope Cleaning: Generally unnecessary, but must be considered in specific cases.
(2) Alignment: While anchor bolt positions have size limitations, some adjustment flexibility exists, especially for anchor rods.
(3) Anchor Rod Fabrication and Installation: Anchor rods should be cut neatly and accurately, with an allowable error within ±50mm. Reserved lengths of steel strand must be allocated for tensioning. Production should occur on platforms at least 50cm above ground, suitable for the design length, and sheltered from sun and rain. Terrain constraints may require production on slope platforms with appropriate weather protection.
5. Grouting of Anchor Holes
(1) When encountering heavily weathered rock or water-rich soil/sand layers in the grouting section, secondary high-pressure splitting grouting should be applied to enhance anchoring strength.
(2) Grouting material must be prepared strictly according to tested and approved proportions. Slurry should be evenly mixed and applied as needed. Anchor hole grouting requires bottom-up grout injection at approximately 2.0 MPa pressure until fresh grout overflows from the hole opening. It is prohibited to pull out the grouting pipe or inject grout from the hole opening. If slurry recedes at the orifice, the hole bottom should be grouted 2–3 times within 30 minutes to ensure complete filling.
6. Installation and Tensioning of Support Ropes
(1) Install longitudinal and transverse support ropes. After tensioning, secure the anchor rod to the exposed sleeve with 2–4 rope clips at each end—2 clips if the rope is under 15m, 4 if over 30m, and 3 clips for lengths in between.
(2) Lay the grid mesh from top to bottom, overlapping grids by at least 5cm. Stitching between grids and connections between mesh and support ropes should be tied with 1.2mm diameter iron wire spaced every 1m.
7. Steel Rope Mesh Laying and Sewing
Steel rope mesh should be laid and sewn from top to bottom. The sewing rope is an 8mm diameter steel rope. Each mesh is sewn and pre-tensioned using a 27 or 31 meter sewing rope along with surrounding support ropes. Both ends of the sewing rope are fixed and connected to the mesh with two rope clips.
8. Process Improvement
After completing the system installation, if conditions allow, press the laid grid flat on the ground using soil or small stones to prevent uplift caused by falling rocks.
Article source: Architectural Technology Magazine
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