Construction technology and application of large polyethylene shielded cabin in China Jinping Underground Laboratory

Abstract

[Objective] Underground laboratories are recognized as critical infrastructure for cutting-edge physical research. To support ultra-low radiation background experiments required for national strategic scientific programs including dark matter detection and neutrino studies, the world's largest polyethylene shielding cabin has been successfully constructed in the China Jinping Underground Laboratory Phase Ⅱ. [Methods] Key construction technologies are systematically elaborated, with a novel design method ology being proposed for large-scale polyethylene shielding cabins under spatially constrained underground conditions. Customized seamless joint configurations are innovatively developed for critical cabin components, while deformation and strength characteristics of polyethylene plates are quantitatively evaluated through finite element simulations. Modular assembly protocols optimized for confined construction spaces are comprehensively documented. [Results] Experimental results indicate that polyethylene plate deformations induced by self-weight stress are controlled within machining tolerances, with cumulative vertical shrinkage deformation measured at 3.0 mm. Maximum stress values in individual polyethylene plates are determined as 87.20 kPa, satisfying both structural stability criteria and assembly precision requirements. Post-construction radiation monitoring reveals the gamma background within the shielded zone is reduced by a factor of 31 compared to external levels, outperforming shielding efficiencies reported from leading international underground facilities. [Conclusion] The assembly structure design of the large polyethylene shielding cabin is scientifically reasonable, the mechanical state of the polyethylene assembly board is stable, the construction quality is well controlled, and the radiation shielding effect has reached world-class level. This technological achievement provides method ological references for ultra-low radiation environment construction and modular engineering implementation in geologically constrained underground spaces.

Keywords

China Jinping Underground Laboratory / large polyethylene shielded cabin / assembled type / stress strain simulation / construction technology / influencing factors / deformation / low radiation background environment