Physical Investigation of Deformation Behaviour of Single and Twin Tunnel under Static Loading Condition

Parvesh Kumar,Amit Kumar Shrivastava

doi:10.3390/app112311506

Abstract

This paper presents a new testing method for the problems encountered in field testing. To this end, single-tunnel and twin-tunnel small-scale rock models are prepared in the laboratory. A new methodology is proposed to encounter problems that are faced during field testing. The test results show that rock strength characteristics, overburden pressure, and tunnel spacing have important effects on the stability of underground structures. For rocks with poor strength properties, the damage degree is greater. When the strength property of rock changes, the deformation value of unlined tunnels changes from 21.05% to 27.58%, while that of lined tunnels changes from 11% to 21.42%. Also, in the twin tunnel, the deformation value reduces from 20% to 15.78% when the spacing between the tunnels is increased. For the measurement of stress and deformation in tunnels, the results obtained from experiments are analyzed. The method adopted in this study helps determine the tunnel’s design parameters to make it safe under overlying static loads. Finally, the key factors affecting the stability of underground structures are determined by simulating the field conditions through experimental research.

Highlights

Excessive deformation in shallow-depth underground structures has always posed a danger to infrastructure safety during the construction of tunnels, when the tunnel crosses a highly stressed induced area, especially in metropolitan areas and mountainous terrain
It is vital to understand how underground systems behave under different loading conditions.In the case of twin tunnels, there is a significant effect of the construction method and position of tunnels on their settlement behaviour [1,2]
TheThe experimental research is performed in ainlaboratory for for this of single and twin tunnels

Summary

Introduction

Excessive deformation in shallow-depth underground structures has always posed a danger to infrastructure safety during the construction of tunnels, when the tunnel crosses a highly stressed induced area, especially in metropolitan areas and mountainous terrain. The stability of underground structures is influenced by various factors such as overburden pressure, in-situ stresses, engineering properties of the rock, and static and dynamic loading conditions. The main aim of design engineers is to minimize the effect of deterioration and keep the structure protected from the stresses that have formed along with its crown, sidewalls, and bottom surfaces during the construction of tunnels. The surrounding soil or rock mass, along with underground structures, is subjected to static load. It is vital to understand how underground systems behave under different loading conditions.In the case of twin tunnels, there is a significant effect of the construction method and position of tunnels on their settlement behaviour [1,2]. In the case of two crossing tunnels, the surface settlement caused due to excavation is greater when the second tunnel is excavated above the first tunnel [12]

Objectives

Results

Conclusion