Compressive Strength and Lightweight Structure of PVC-U 7-Hole Pipes ——Telecom Pipeline Applications Based on Q/CTP 001-2023 Standard

1. Research Background


PVC-U 7-hole pipes for telecom optical cables face conflicts between low compression resistance and material waste at 1.5-3m burial depth:


  • Traditional pipes (Figure 1) have SN4 ring stiffness, insufficient for >2m under roads
  • Increased wall thickness leads to 6.5kg/m weight, +20% transportation cost
  • 18% construction damage rate, 12% higher than single-hole pipes

2. Core Issue: Multi-Hole Mechanical Conflict

2.1 Structural Parameters


FEA analysis (ANSYS) identifies critical parameters:


Parameter Traditional Design Optimization Goal
Hole arrangement Plum blossom Honeycomb (uniform stress)
Rib thickness (mm) 2.0 Increase to 2.5-3.0mm
Wall thickness (mm) 3.0 Reduce to 2.5mm (material savings)

2.2 Failure Modes


Failure Type Cause Typical Scenario
Flattening Vertical load >8kN/m² Under main roads
Shear Horizontal soil pressure >5kPa Pipe bends
Impact Construction machinery collision Trench excavation

3. Lightweight Structure Optimization

3.1 Hole Arrangement


Comparison of dn110mm pipe arrangements:


Arrangement Ring Stiffness (kN/m²) Weight (kg/m) Stress Concentration Factor
Plum blossom 4.8 6.2 1.8
Honeycomb 6.5 5.8 1.2 (Optimal)
Linear 5.2 6.0 1.5


Breakthroughs:


  • Hexagonal honeycomb arrangement (Figure 2) with 120° rib angles
  • Stress uniformity +33%, material efficiency +15%

3.2 Rib Structure Innovation


"I-shaped" ribs replace traditional rectangular ribs:


  • Thickness reduced from 2.0mm to 1.8mm
  • Moment of inertia +22%, ring stiffness +18%
  • Weight reduction 0.6kg/m

4. Material & Process Optimization

4.1 Nano-Composite Modification


Adding 2% nano-CaCO₃ + 1% glass fiber:


Material Type Tensile Strength (MPa) Elastic Modulus (GPa) Elongation at Break (%)
Traditional PVC-U 48 2.8 200
Reinforced PVC-U 55 3.5 180
Pure PC 62 2.4 120

4.2 Gas-Assisted Injection


Compared to traditional injection:


  • Wall thickness deviation from ±0.3mm to ±0.1mm
  • Residual stress -40%
  • Cycle time -25%

5. Engineering Solutions

5.1 Telecom Pipeline Standard


Based on Q/CTP 001-2023:


Parameter GB Requirement Optimized Standard Test Method
Ring stiffness (kN/m²) ≥4 ≥6 GB/T 9647-2015
Flattening deformation (%) ≤10 ≤5 GB/T 8804.2-2003
Drop weight impact (TIR) ≤10% ≤5% GB/T 14152-2001

5.2 Compression Construction


"Three Supports One Backfill" method:


  1. Sand cushion: 150mm medium-coarse sand (compaction ≥95%)
  2. Concrete supports: Triangular blocks every 2m
  3. Backfill: Graded gravel + geotextile

6. Field Test Case: Municipal Telecom Project


Index Traditional Pipe Optimized Pipe Standard Requirement
Ring stiffness (kN/m²) 4.5 6.8 ≥6
Unit weight (kg/m) 6.5 5.2 -
Construction damage rate (%) 18 7 ≤10

7. Advanced Technology Prospects

7.1 3D-Printed Custom Pipes


FDM technology enables variable wall thickness and complex hole shapes, with 98% material utilization.

7.2 Smart Monitoring Pipes


Distributed fiber sensors monitor deformation and cable temperature (±0.5mm accuracy).


Conclusion
This paper balances lightweight and high compression through structural innovation + material reinforcement + process optimization. As a professional supplier, we provide:
✅ Custom telecom 7-hole pipes (dn75-dn160mm)
✅ Pipe structural analysis reports
✅ Third-party compression testing


Keywords: PVC-U 7-hole pipe, compressive strength, lightweight, telecom pipeline, Q/CTP 001

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