One, what is the slope protection net?
Slope protection mesh, also known as retaining mesh, is a protective device used in highway and railway slope stabilization. It is classified into active and passive protection methods.
Active protection systems consist of flexible mesh nets, primarily made of steel wire, that cover and enclose the required protective slope or rock face to limit soil erosion or damage, as well as rockfalls and landslides (reinforcement function), or to control falling rocks within a certain range (containment function).
Passive protection is composed of four main parts: steel wire mesh, hoop mesh, (an additional wire mesh layer is required to intercept small falling rocks), a fixing system (anchor bolts, tie rods, bases, and support ropes), and a pressure reduction ring and steel columns. The steel columns and steel wire mesh are combined to form a whole, providing surface protection to the area being protected, thus preventing the collapse of soil and rock, and achieving slope protection.
Two. Function of slope protection mesh
1. Ensures the even distribution of seeds on the slope surface and protects them from wind and rain, preventing loss.
2、Before the grass has grown, it can protect the soil surface from erosion caused by wind and rain.
3. Due to the rough surface, wind and water flow generate numerous vortices on the mesh pad, thereby reducing energy and causing the carried material to settle within the mesh pad.
4、Black mesh padding can absorb a large amount of heat, increase soil moisture, and extend the plant's growth period.
5. Can replace long-lasting slope protection materials such as concrete, asphalt, and stone blocks, used for protecting slopes on roads, railways, rivers, dams, and mountains.
6. The composite protective layer formed after plant growth can withstand high water levels and rapid water flow.
7. After laying the sand surface, it can prevent sand dune movement, increase surface roughness, accumulate surface sediments, and modify the physical and chemical properties of the surface, thereby improving the local ecological environment.
8、Significantly reduces construction costs, representing 1/7 the cost of C15 concrete and dry-stacked stone wall construction, and 1/8 the cost of masonry block construction.
III. Construction Method for Slope Protection Net
(1) Construction Preparation
To ensure the quality of the passive protection net installation in the shed, it is required to thoroughly plan and arrange personnel, machinery, and materials before construction. Strict quality control of incoming raw materials and the enhancement of technical skills, particularly for on-site operators, are also essential.
1. Personnel Organization
(1) First, conduct a thorough technical briefing for all personnel involved in the construction, ensuring they fully understand the specific construction process and establish a quality-first mindset. Organize a technical training session led by the project chief engineer, familiarizing the workers with the construction process for the arch and frame structure, enabling them to understand the process clearly and ensure smooth and orderly execution on the construction site.
(2) Furthermore, a strict work-shift system is implemented to ensure that a primary construction supervisor is present on-site during each work period for management and technical guidance, with sufficient on-site personnel to ensure worker rotation and prevent fatigue.
2、Material Composition
based on the on-site construction organization, all required materials should be delivered to the site in advance before construction begins. All materials entering the site must undergo laboratory inspection and meet the requirements for raw materials specified in the tender documents.
- Steel wire rope: Minimum nominal tensile strength of 1770 MPa, hot-dip galvanized to AB grade.
High-strength steel wire mesh: A steel wire mesh woven from anti-vibration and anti-detachment locking strands, with a diamond shape.
Welded mesh: Meets standard requirements.
Vacuum ring: diameter of 448cm.
Steel columns: Utilizing double-arch reinforced prestressed steel columns.
(II) Construction Plan
1、The passive safety system should be arranged along the contour lines.
2、The maximum initial vertical distance of the passive safety system is limited to 3% of the column spacing.
3、Pull-out resistance of the upper pull-out anchor, intermediate reinforcing pull-out anchor ≥ 40KN, and side pull-out anchor ≥ 50KN.
4、Anchoring: For solid, stable ground conditions, use Class A anchoring. For loose, soft ground conditions, use Class B anchoring. Class A Anchoring: For steel column foundations and anchor holes, if the ground layer is stable bedrock or has a very thin covering, anchor holes can be drilled directly. Then, anchor with M30 cement mortar or pure cement grout. Class B Anchoring: For steel column foundations and anchor holes drilled into soil layers, the anchor strength decreases after forming. Therefore, use C20 reinforced concrete. The steel cage should be made of Ф16 threaded steel bars, and the concrete cover should be at least 20mm to improve the anchoring strength.
5. When using Class A anchoring, the diameter of the steel column concrete foundation base anchor holes should not be less than Φ42. The top surface of the foundation should be leveled with a thin layer of C20 fine concrete or M20 cement mortar.
6. When the underlying soil layer is less than the depth of the concrete foundation, the covering layer can be replaced with concrete, and anchor holes can be drilled directly into the lower portion to create a composite foundation.
7. Steel column foundation anchor bolts are fabricated using φ28 thread steel reinforcement, with a total length of 5m. The top end has a M27x100 thread. The anchor hole diameter is φ42, and the pull anchor rope uses a φ16 double-strand steel rope with a total length of 5m. The anchor hole diameter must be no less than 42mm.