Analysis of Shield Tunnels Undercrossing an Existing Building and Tunnel Reinforcement Measures

Abstract

Research on tunnel excavation has rarely considered the effect of the tunnel excavation on a complete building. Therefore, this paper considered a building with a double basement and piles, and a three-dimensional finite-element model for shield tunnels undercrossing an existing building was established to study the effects of the excavation of double-shield tunnels on the displacement and internal forces of soil, segments, piles, and buildings. Grouting reinforcement technology was used in the model to analyze the effect of grouting reinforcement on pile displacement and building subsidence. The results showed that for every 100 kPa increase in grouting pressure, the maximum subsidence of the soil was reduced by 3.512 mm. The successive excavation of double-shield tunnels resulted in elliptical segments. The longitudinal and transverse stresses of the segments were effectively reduced by grouting pressure of 250 kPa. The excavation of tunnels had an obvious nonlinear effect on the maximum lateral displacement of the piles along the direction of excavation and the maximum subsidence of the building. When using deep-hole grouting reinforcement, the maximum lateral displacement of piles and the maximum subsidence of the building were effectively reduced by increasing the radial grouting reinforcement radius and adjusting the reinforcement range.

Effect of Undercrossing Shield Tunnels Excavation on Existing Rectangular Pipe-Jacking Tunnels

“…Up until now, many scholars have conducted research on similar projects involving the construction of new shield tunnels beneath existing structures. That research is mainly divided into four types: theoretical calculation [12][13][14][15][16][17][18][19], numerical modeling [20][21][22][23][24][25][26][27][28], model testing [29][30][31], and field monitoring [32][33][34][35]. Zhang et al [36] proposed an analytical solution in order to analyze the response of an existing tunnel to a new tunnel excavation underneath.…”

Safety Evaluation of Crossing Tunnel Engineering: A Case Study

“…In order to meet the transportation demands, a considerable number of new road projects are being implemented, resulting in a proliferation of existing roads intersecting or running parallel to one another, and leading to the rise of road-related projects [1]. The construction of road-related projects poses significant risks for existing road infrastructure, especially for road tunnels which require excavation and explosion [2,3]. During the construction process of such projects, blasting vibrations induced by new tunnel excavation may cause fissures, cracks or even collapse in medium and harder rocks [4][5][6][7], and cause ground collapse in strongly weathered rock mass [8][9][10], thereby compromising road safety.…”

Dynamic Mechanical Characteristics of Horseshoe Tunnel Subjected to Blasting and Confining Pressure

“…The dynamic loading from nearby blasting combined with the prestress cause the crack initiation and development in surrounding rock masses [1,2]. The spalling or breaking along the tunnel's free surfaces becomes a potential threat to the safety of construction and support [3,4].…”