Abstract
This paper analyzed the earth pressure, pore pressure, and surface settlement of the Luoyang urban rail transit tunnel in a sandy gravel stratum (Henan Province, China) under different burial depths by using field measurement methods. The results showed that the earth pressure as well as pore pressure of the soil layer above the working surface increased sharply and reached their maximum values when the cutter head of the shield gradually crossed the working surface. During the completion of synchronous grouting, the earth pressure and pore pressure increased slightly; when shield tunneling passed through the working surface, the earth pressure is smaller than the original earth pressure due to the unloading effect. The surface settlement curve above the tunnel took on a “V” shape after the completion of the left-side tunnel excavation, conforming to the normal distribution pattern. The surface settlement curve above the two tunnels took on a “W” shape after the completion of the right-side tunnel excavation, which is in good agreement with the proposed theoretical calculations. The findings of this study can help for better understanding the control of safety risk during shield construction.
Highlights
To improve increasingly congested road traffic, many cities in China have begun to build subways
From the perspective of the construction direction, for the measurement points located on both sides of the tunnel, the shield tunnel is disturbed by the shield construction, resulting in pore pressure
When the shield tunnel crossed the working surface, due to the unloading of the soil, the earth pressure is smaller than the original earth pressure, gradually
Summary
To improve increasingly congested road traffic, many cities in China have begun to build subways. The self-stability of sandy gravel strata is poor, so accidents occur as shield tunneling is excavated. The important impact of shield tunnel construction on soil disturbance is the settlement caused by front excavation and the filling of shield gaps. The stability analysis of the excavation surface and the impact of the shield tail grouting process are very important. There are many difficulties in constructing shield tunnels in sandy gravel strata. It is very important for the safety of surrounding buildings and various facilities to grasp the law of the influence of the entire construction process on soil disturbance (Bai and Li, 2013; Hamrouni et al, 2019; Bai et al, 2021a)
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