Model Test and Numerical Simulation Analysis on Freezing Effect of Different Freezers in Freeze-Sealing Pipe-Roof Method

Haibing Cai,Zongjin Wang,Yujie Liu,Mengkai Li,Rongbao Hong,Hanglong Ding,Xinyu Ye

doi:10.1155/2022/5350650

Abstract

The Gongbei Tunnel Project is a key phased project of the Zhuhai Connection Line of the Hong Kong–Zhuhai–Macao Bridge, and the freeze-sealing pipe-roof (SFPR) method was first applied successfully. During this period, in order to obtain the best arrangement of freezers, three configurations, that is, solid pipe with circular freezer (SCF), empty pipe with double circular freezer (EDCF), and empty pipe with special-shaped freezer (ESF), were designed to analyze their freezing effects. The model test results show that the freezing temperature fields excited by different arrangements of freezers are obviously different, and the freezing effect of ESF is the best. The numerical simulation results indicate that the temperature cloud diagram of SCF at 42 h is butterfly-shaped after opening the limit pipes, and the temperature cloud diagrams of ESF and EDCF are the same as the model test results. However, the processing method of ESF is relatively complex, which adopts arc angle steel welding requiring a lot of reverse welding and high welding quality. Eventually, EDCF is recommended to ensure the quality of frozen walls due to its lower cost and better freezing effect. This research plays a basic role in the implementation of the freeze-sealing pipe-roof method.

Highlights

With the further progress of urbanization, the development and utilization of urban underground space are facing an increasingly harsh construction environment [1], especially, it is more severe during the construction of urban tunnels in shallow and water-rich strata
A new freezing configuration that empty pipe with a double circular freezer (EDCF) is proposed based on the exiting two freezing configurations (SCF and empty pipe with special-shaped freezer (ESF)), and it has the advantages of lower cost and convenient processing. erefore, it is meaningful to determine the optimal arrangement of freezers from many aspects among these three freezing configurations
ESF adopts arc angle steel welding, which is difficult to operate, and considerable seam welding and overhead welding must be performed. e welding requirements are high, the freezing liquid may leak, and the maintenance cost is high in the later stage. erefore, empty pipe with double circular freezer (EDCF) can be used instead of ESF to ensure the freezing effect of the frozen wall

Summary

Introduction

With the further progress of urbanization, the development and utilization of urban underground space are facing an increasingly harsh construction environment [1], especially, it is more severe during the construction of urban tunnels in shallow and water-rich strata. Under this background of urban construction, the artificial ground freezing (AGF) method has been widely used due to its environmental friendliness [2]. Qi et al [15] studied the temperature field expansion of basinshaped freezing method through physical model test and numerical simulation; it shows the gradual development of freezing from backwater surface to front water surface under seepage condition. All the basic research is the expansion and enrichment of the SFPR technique, which provides a favorable reference for the follow-up projects similar to the Gongbei tunnel

Project Overview

Similarity Criterion

Analysis of Model Test Results

Numerical Simulation and Discussion

Conclusions