1. Research Background MPP (Modified Polypropylene) power pipes play a critical role in urban power grid upgrades due to their Vicat Softening Temperature (VST) ≥ 120℃, outperforming ordinary PE pipes. However, State Grid testing reveals: When cable current exceeds 600A, long-term operating temperature reaches 85-95℃ Traditional MPP pipes exhibit 3.2% creep strain at 80℃/10MPa after 5000 hours (close to failure threshold 3.5%) 2. Core Issue: Thermo-Mechanical Coupling Failure Mechanism 2.1 Three-Stage Creep Process Through Dynamic Mechanical Analysis (DMA) and long-term hydrostatic tests (GB/T 6111-2018), MPP pipe creep behavior is divided into:  Instantaneous Elastic Deformation (0-100h): Strain <0.5% Steady-State Creep (100-5000h): Strain rate 0.002%/h Accelerated Failure (>5000h): Plastic...

1. Research Background MPP (Modified Polypropylene) power corrugated pipes, featuring a "corrugated structure + high-temperature resistance modification" (Figure 1), have become the preferred choice for trenchless laying of 10kV-35kV power cables. Compared to traditional PVC-C pipes, they increase pulling construction efficiency by 40%. However, in long-distance directional drilling (>500m) and large-curvature bends (R < 15D), pipe failures are prominent: According to 2024 State Grid statistics, 32% of MPP pipe construction accidents are caused by tensile fractures. 28% of municipal engineering reworks are due to bending instability. 2. Core Issue: Mechanism of Mechanical Failure in Pulling Pipes Through full-scale pulling tests (referencing CECS 165:2004) and finite element simulation, three failure modes and...

I. Research backgroundPVC 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 analysisThrough the ring stiffness test (GB/T 9647) and finite element...