GB/T 39705-2020 in English

This standard specifies the technical requirements for the entire life cycle of rail transit roadbed vibration isolation pads made of polymer materials, covering key links such as design, production, inspection, and construction. It is applicable to ballasted/ballastless track systems in urban rail transit and plays an important role in regulating the transmission of wheel-rail vibration.

1. Dynamic and static modulus control

The standard innovatively proposes the requirement of dynamic and static modulus ratio ≤1.3 (under 4Hz test conditions), which is achieved through the special test fixture specified in Appendix A/B:

• Use 300mm×300mm complete structural unit specimen
• Sandpaper interface treatment (P120 grit) to eliminate sliding error
• Three displacement meters synchronized measurement to ensure data accuracy

2. Fatigue performance verification

Refer to Appendix C for 10 million times load cycle test (3-5Hz):

• Thickness change rate ≤3%
• Static foundation modulus change rate ±10%
• No surface damage or delamination

Key points for quality control

1. Raw material batch management: Pay special attention to the Mooney viscosity fluctuation control of rubber/polyurethane materials
2. Production process monitoring: Microporous structure products need to control the foaming uniformity (density gradient ≤5%)
3. Finished product inspection frequency: Dynamic modulus test is recommended to be sampled once every 5000㎡

Engineering application guidance

Note during construction:

• Foundation flatness ≤3mm/2m
• The cut surface of the microporous mattress needs to be treated with special sealant
• The splicing parts adopt stepped overlap, and the overlap length is ≥50mm

This standard unifies the technical specifications of vibration isolation pads in the field of rail transit for the first time. The main innovations include:

• Establish a dynamic and static modulus correlation evaluation system
• Introduce long-term fatigue performance verification requirements
• Clarify the common technical indicators of different track forms (ballasted/ballastless)

Compared with the old industry regulations, new key technical indicators such as dynamic foundation modulus and post-fatigue performance retention rate have been added, which are more in line with the long-term requirements of rail transit vibration control.