GB/T 39395-2020 in English

Analysis of the core content of the standard

This standard is modified to adopt the ISO13267:2010 international standard, mainly for the compressive performance test of the thermoplastic inspection well manhole seat under the combined force of soil and groundwater, and innovatively proposes three test methods:

Key technical requirements

1. Sample preparation

The sample consists of a well seat and a wellbore of at least 300mm. The double-wall structure needs to have a 3-4mm through hole in the inner wall. State conditioning requires that the test can be conducted 21 days after production and that the test be conditioned at 15-25℃ for 6 hours.

2. Deformation measurement specification

An innovative flow channel deformation calculation formula is proposed:
Longitudinal deformation Y_V=[(ΔH_L+ΔH_R)/2]-ΔH_W
Transverse deformation Y_H=ΔW₁+ΔW₂

3. Data extrapolation method

The least square method is used to establish the deformation-time logarithmic curve, and the correlation coefficient R≥0.99 is required. When the data does not meet the linear requirements, the test needs to be extended to 4000 hours.

Main differences from ISO13267:2010

• Added channel deformation calculation formula (missing in the original international standard)
• Deleted the definition of manhole well and focused on inspection well products
• Adjusted the reference standard: replaced ISO9967 with GB/T18042
• Modified the test schematic diagram and clarified the relationship between the device and the sample

Project implementation suggestions

1. Preferably use the sandbox method to simulate the actual buried working conditions
2. Deformation measurement should use an electronic dial indicator with an accuracy of 0.1mm
3. For large-diameter well seats, it is recommended to extend the test to more than 2000 hours
4. Regularly calibrate the pressure source device to ensure that the deviation is ≤0.1kPa