Emergency Restorability of Underground Engineering Environment after Disasters by Utilizing Prefabrication and Assembly Technology

Abstract

Urban development is promoting aboveground-underground city integration. Underground engineering and surrounding buildings and infrastructure form an underground engineering environment (UEE). In critical disasters, damage to the UEE not only causes chain damage to the surroundings but also aggravates urban resilience. Few studies have focused on UEE resilience and its disaster reduction. This study investigated the emergency restorability of the UEE to fill this research gap. First, we classified the restoration levels based on UEE damage patterns. Second, we performed subregion optimization based on cast-in-situ (CIS) restoration, and technical optimization by utilizing prefabrication and assembly technology (PAT). Third, the CIS/PAT UEE emergency restorability functions were constructed based on these optimizations and the local assembly capacity. Finally, the performance of the CIS/PAT restoration, optimization effect, and local assembly capacity were analyzed using a case study. The results indicated that (1) meticulous subregion optimization significantly reduced environmental work with a 13.5% speed up; (2) technical optimization incorporating PAT had the highest efficiency for improving UEE emergency restorability; (3) PAT restoration enhanced the structural resilience and functional resilience of the UEE by at least 28.34% and 62.27% over CIS restoration, respectively; (4) upper and lower thresholds exist for assembly speed in PAT restoration; (5) there exist three types of assembly capacity in PAT restoration: ring-quantity-sensitive, ring-weight-sensitive, and insensitive; and (6) the adaptive schemes maximized the performance of different local assembly capacities in PAT restoration. The UEE emergency restorability function provides a quantitative assessment tool for the resilience of UEE and a resilience enhancement scheme for disaster reduction.