I. Research background
PVC double-wall corrugated pipe has a share of 42%** in the field of municipal drainage and sewage disposal in building communities by virtue of the structure design of **“outer wall corrugated + inner wall smooth” (Figure 1) (2024 China Plastics Processing Industry Association data). However, traditional products face two major contradictions:
Insufficient ring stiffness: easy to deform when the depth of soil cover > 3m (58% of the failure cases)
Excessive weight: dn300mm pipe weighs 12kg/m, increasing transportation cost.
Second, the core problem: structure - performance contradiction analysis
Through the ring stiffness test (GB/T 9647) and finite element simulation, three major defects of traditional design are found:
Problem dimension Traditional design parameters Optimization needs
Ripple shape Trapezoidal wave (angle 70°±5°) Enhancement of crest bending resistance
Wall thickness distribution Equal thickness of inner and outer walls (2.5mm) Optimize material distribution efficiency
Connection method Single seal ring socket Reduce interface stiffness loss
Structure optimization experimental research
1. Orthogonal test of corrugated shape
Adopt ** Response Surface Method (RSM) to optimize wave height (H), wave pitch (P), angle (θ)** three parameters:
Scheme H(mm) P(mm) θ(°) Ring stiffness (kN/m²) Weight (kg/m) Composite performance index *    
A 15 30 80 8.2 10.5 0.78    
B 18 25 90 9.8 9.2 0.95 (optimum solution)
C 20 20 100 10.1 11.0 0.92    
* Combined Performance Index = Ring Stiffness / Weight
The optimized structure is shown in Fig. 2:
90° right-angle wave with triangular reinforcement at the crest.
The wave pitch is reduced by 20% and the material is concentrated towards the wave crest.
2. Gradient wall thickness design
Non-equal wall thickness distribution is realized by melt flow analysis (Moldflow):
Outer wall crest wall thickness 3.2 mm (70% load)
2.0 mm wall thickness in the inner smooth layer (to ensure fluid performance)
Transition zone wall thickness 2.5mm (to reduce stress concentration)
Engineering solutions
1. Performance upgrade based on GB/T 19472.1
Indicator National standard S2 level requirements Optimized standard Test method
Ring stiffness (kN/m²) ≥8 ≥10 GB/T 9647
Impact strength (TIR) ≤10% ≤5% GB/T 14152
Ring flexibility No rupture Residual deformation <3% Vertical outer diameter deformation test
2. Lightweight connection technology
Lightweight connection technology **"Double locking + step sealing ”** interface design (Figure 3):
Mechanical locking: corrugated groove and socket tabs occlude, 40% increase in pull-out resistance.
Step sealing ring: EPDM double sealing, compression rate 15% → 20
Thermal fusion auxiliary: dn ≥ 300mm pipe with localized thermal fusion welding, interface stiffness retention rate of 95
V. Test case: a sponge city project
Indicator Traditional S2 pipe Optimized pipe Enhancement effect
Maximum depth of soil cover 3.0m 4.5m +50%
Weight per unit length 11.8kg/m 9.5kg/m -19
5-year leakage rate 2.1 times/km/year 0.4 times/km/year -81% Transportation cost ￥1200 / ton
Transportation cost ￥1200/ton ￥980/ton -18%.
Extension of cutting-edge technology
1. Bionic bamboo structure design
Based on the principle of bamboo vascular bundles (Figure 4), spiral reinforcement ribs are added to the inner wall of the corrugated pipe, which can further increase the ring stiffness by 15%.
2. Application of recycled materials
The use of chemically depolymerized recycled PVC (purity > 99%) can be realized:
25% reduction in material costs
38% reduction in carbon emissions
Performance retention rate ≥90%.
Conclusion
Through structural innovation + material optimization + connection upgrading, this paper achieves the goal of double-wall bellows **"stronger, lighter, more economical ”**. As a professional supplier, we offer:
✅ Customized ring stiffness design solutions
✅ Third-party certification of lightweight products
✅ Full life cycle costing tools
Keywords: PVC double wall corrugated pipe, ring stiffness, lightweighting, drainage pipe, GB/T 19472