Effect of Excavation Blasting in the Arch Cover Method on Adjacent Existing Pipelines in a Subway Station

Xiang Liu,Lu Hai,Annan Jiang,Xinping Guo

doi:10.3390/app12031529

Abstract

The dynamic responses of existing pipelines are of great significance to be studied in blasting excavation in the arch cover method. In this paper, the Shi Kui Subway Station Line 5 in Dalian, China, is selected as a case study. A 3D numerical simulation model is established to analyze the dynamics characteristics of the existing pipelines subjected to blasting vibration, with a triangular pattern describing the blast hole pressure. The numerical simulation is verified by comparing the existing pipelines’ PPVs of the numerical model and field monitored points. Then, the dynamic responses of the pilot tunnels, existing pipelines, and secondary lining are discussed. The effects of the later pilot tunnel on the earlier pilot tunnel are remarkable when the relative distance between them is small. Extensive blasting areas and many charges will result in large peak velocities of the existing pipelines in a short time, as well as a decreased distance from the pilot tunnels. However, the hollow effect can change these dynamic characteristics. The implementation of a secondary lining can reduce the existing pipelines’ dynamic responses when the lower rock is blasted. The most adverse position of the secondary lining is the arch foot rather than the arch crown and arch waist; thus, blasting should be carried out at a suitable age for the concrete to ensure the safety of the structures and pipelines.

Highlights

The arch cover method, developed from the traditional shallow tunneling method [1], is widely used to construct subway stations in the upper‐soft lower‐hard stratum
This paper aims to study the dynamic responses of the existing pipelines subjected to blasting excavation by the arch cover method
In this paper, four existing pipelines adjacent to the blasting of a subway station were taken as a case study to analyze the dynamic responses induced by the arch cover method

Summary

Introduction

The arch cover method, developed from the traditional shallow tunneling method [1], is widely used to construct subway stations in the upper‐soft lower‐hard stratum. Some cities, such as Dalian, Chongqing, and Qingdao in China, have applied the arch cover method to station construction, including two different types of primary lining support and double lining support. The main concerns of the research are tunneling‐induced ground deformation, the mechanical responses of the sup‐ porting structures, the deformation control effect of various support methods, and the optimal construction sequences. The construction sequences, composed of constructing and dismantling the temporary support, erecting and removing the mid‐pillar, setting up the secondary lining, middle plate, and floor, are the critical construction technologies of the arch cover method to control the ground deformation and ensure the safety of subway station

Objectives

Methods

Findings

Conclusion