Abstract
The construction scale of the shield tunnel underpass is expanding day by day. In order to study the safety influence and deformation control of the shield tunnel underpass on the existing tunnel, the LSSVM model is established. Based on the collected soil storage pressure, foam volume, simultaneous grouting volume and other six shield construction parameters and corresponding sample data of the tunnel bottom displacement, the horizontal displacement and settlement displacement of the existing tunnel bottom caused by the approach construction are predicted. Taking a subway project as an example, the research results show that the prediction model of shield tunneling under the existing tunnel bottom level and settlement displacement has strong generalization ability and rapid and accurate prediction effect. This method can provide reference for similar projects.
Highlights
With the widespread rise of my country's underground rail transit system, there are more and more shield tunnel construction projects
In order to ensure the safety of subway tunnel construction and operation, it is of great significance to adopt reliable measures to predict horizontal displacement and settlement displacement[1]
The optimization results of the prediction parameters of the arch bottom horizontal displacement and the arch bottom settlement displacement are shown in Fig. 1 and Fig. 2 respectively
Summary
With the widespread rise of my country's underground rail transit system, there are more and more shield tunnel construction projects. There are three main research methods: theoretical formula[2], numerical simulation[3], and model test[4] Theoretical formula method such as Wang et al.[5]derived the differential equation of adjacent pipeline deformation caused by tunnel excavation based on the Winkler foundation model to analyze the uplift or settlement deformation. Numerical simulations such as Li et al.[6] used FLAC3D to establish a three-dimensional numerical simulation model, and analyzed the impact of the staged construction of the foundation pit on the station and the existing subway tunnel. A shield construction parameter index system is established to make highprecision nonlinear predictions of the horizontal displacement and settlement displacement of the existing tunnel bottom. The optimal regression function can be obtained by the least square method as[12]: l f x ai yi K xi , xj b (3) i 1
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