The passive rockfall barrier (also called rockfall catch fence or SNS passive protection) is a fence-type structure installed at the toe of slopes to catch and stop falling rocks. Unlike active systems that cover slopes, passive barriers are positioned where rocks are expected to land β intercepting them safely.
## How Passive Protection Works
1. **Rock Detachment**: Rock detaches from slope face above the barrier
2. **Impact**: Rock strikes the ring net panel β kinetic energy transferred to the system
3. **Brake Activation**: Brake elements (compression tubes) deform, absorbing kinetic energy
4. **Net Deformation**: Ring net stretches and deforms β absorbing remaining energy
5. **Post Yielding**: Steel posts may tilt on their bases β absorbing final energy
6. **Rock Retention**: Rock comes to rest in the deformed net β prevented from continuing downslope
7. **Maintenance**: Deformed components (brakes, net section) replaced. System restored.
## Energy Absorption Chain
The 100kJ system absorbs energy through a cascade of deformable elements:
- **Brake Elements** (60% of energy): Compression tubes that crush at controlled load
- **Ring Net** (25% of energy): Steel rings that deform and spread load
- **Post Foundation** (10% of energy): Posts tilt on hinged bases
- **Anchor Elongation** (5% of energy): Anchor cables stretch slightly
## Key Advantages
- **Proven Performance**: Hundreds of field tests worldwide. 100kJ = catches 1000kg rock at 10 m/s.
- **Controlled Deformation**: System is designed to deform β not break. Energy is absorbed, not reflected.
- **Repairable**: After impact, replace damaged brake elements and net section. Posts and anchors usually reusable.
- **Cost-Effective**: 10-30% of cost of active mesh covering entire slope. Only intercepts at danger zone.
- **Scalable**: Multiple barrier rows for high slopes. Heights from 3m to 7m.
- **Minimal Site Impact**: No slope excavation needed. Posts anchored in ground at toe.
## Technical Specifications
| Parameter | Value |
|-----------|-------|
| System Type | Passive (rockfall catch fence) |
| Energy Capacity | 100 kJ |
| Net Type | Ring net (ROCCO R7/3/300) |
| Ring Diameter | 300mm |
| Ring Wire | 3.0mm x 7 loops (=7x3mm) |
| Net Height | 3.0m, 4.0m, 5.0m (standard) |
| Post Spacing | 10m (standard) |
| Post Type | Steel HEA 140 / HEA 160 |
| Brake Element | Compression tube (controlled deformation) |
| Anchor Cable | 16mm steel rope, 5-8m depth |
| Foundation | Concrete block 600x600x600mm |
| Wire Coating | Zn-5%Al (Galfan) >=150g/m2 |
| Standard | ETAG 027, GB/T 31444 |
| Certification | ISO 9001, CE |
## Applications
- **Highway Rockfall Zones**: Toe of rock cuts where rockfall endangers traffic
- **Railway Lines**: Slope toe adjacent to rail corridors
- **Mountain Roads**: Below natural rock slopes and cliffs
- **Industrial Facilities**: Below slopes adjacent to factories and storage
- **Residential Areas**: Below slopes near homes and developments
- **Power Transmission**: Below slopes near transmission towers and lines
- **Pipeline Routes**: Below slopes along oil and gas pipeline corridors
## Packaging & Delivery
- **Packaging**: Net panels rolled. Posts palletized. Brake elements and hardware in cartons.
- **Container Loading**: 20ft GP ~ 200-400m of barrier; 40ft HQ ~ 400-800m
- **Lead Time**: 15-25 days standard; 25-40 days custom heights/energy ratings
- **Shipping**: FOB Tianjin / CIF / DDP