Ground settlements above a tunnel as a result of tunnel construction can be predicted with the help of input variables that have direct physical signiﬁcance Several empirical and artificial intelligence methods for estimating ground settlements have been established by researchers However, these methods have some limitations because the large number of influential factors involved makes tunnel–ground interaction complicated In this work, a random forest (RF) was developed and employed to predict ground settlements above tunnels To achieve this goal, tunnel geometry, geological properties, and construction parameters were investigated as input variables to utilize in the RF modeling, resulting in the maximum surface settlement value (Smax) and trough width (i) as the ground surface settlement index To demonstrate the applicability of the RF model, two data sets associated with different features, which were obtained from a detailed investigation of different tunnel projects published in litera

Feasibility of Random-Forest Approach for Prediction of Ground Settlements Induced by the Construction of a Shield-Driven Tunnel

Effect of particle shape on the progressive failure of shield tunnel face in granular soils by coupled FDM-DEM method

https://re.public.polimi.it/bitstream/11311/1007702/1/article.pdf

Chemo-mechanical modelling of the external sulfate attack in concrete

This paper presents a study on the mechanical behavior in a long pipe roof during excavation of a shallow bias highway tunnel in loose deposits. The mechanical parameters of the surrounding soil were obtained by triaxial consolidated-drained shear tests on large reconstituted specimens. Three-dimensional numerical modeling was conducted to simulate the tunnel construction process. Six typical construction stages were simulated to analyze the effects of tunnel support elements, topographic and geological conditions on the mechanical behavior of the pipe roof. The modeling results revealed the variation of force and bending moment distribution in the pipe roof during excavation. Three main conclusions were drawn: (1) for the shallow and asymmetrically loaded tunnel buried in loose deposits, a pipe roof at the entrance can effectively reduce the stresses and asymmetric loading between the tunnel support elements and enhance the tunnel safety during construction; (2) because of asymmetrical stresses, the umbrella arch could shoulder much of the axial force of the pipe roof and the protection arch could reduce the force on the pipe roof effectively; (3) influenced by the asymmetric topography, the maximum force and bending moment in the pipe roof occurred mainly in the upper right tunnel heading. As the stiffness of the retaining wall, protection arch, umbrella arch, and the surrounding loose deposits were different, the force and bending moment distribution in the pipe roof was highly non-uniform during excavation. The simulation results should be significant both for the pipe roof design and the construction of other tunnels in similar geologic conditions.

Analysis of mechanical behavior in a pipe roof during excavation of a shallow bias tunnel in loose deposits

A microstructural hydration model for cemented paste backfill considering internal sulfate attacks

An analytical solution is presented to predict ground movement induced by a nonuniformly deforming circular tunnel in a heavy elastic half-plane. Simple expression is proposed to describe the nonuniform soil deformation around the tunnel. The tunnel-deforming components (i.e., ground loss, ovalization, vertical translation) can be determined by the solution-inherent mechanism and by fitting from measured field data. The effects of tunnel-deforming components on the resulting displacement field are discussed. Case studies from various ground conditions were used to check the capacity and applicability of the proposed solution. Although elasticity is a rough representation of the soil behavior, the proposed analytical solution can serve as a simple tool for predicting a reasonable ground settlement profile in the preliminary design of tunnels.

Analytical Prediction of Ground Movements due to a Nonuniform Deforming Tunnel

Experimental study on the damage mechanism of tunnel structure suffering from sulfate attack

Cyclic and post-cyclic shear behavior of low-plasticity silt with varying clay content

Silt specimen reconstitution using a slurry consolidation approach is commonly used for laboratory testing. This paper presents a new slurry consolidation approach to reconstitute silt specimens for use in triaxial testing. Silt specimens were reconstituted in a split vacuum mold mounted on a special experimental setup. The uniformity of the reconstituted specimens was verified by measuring the water content and grain size distribution throughout the specimens. The testing program was expedited using a special sample handling technique to move the specimen from the special experimental setup to the triaxial chamber base platen. The handling process did not disturb the specimens to a measurable degree. Further, the replicas of the reconstituted specimens were verified by submitting them to basic volumetric measurements followed by static and cyclic triaxial tests. The triaxial test results reported very small differences.

Shuying Wang

Papers

Analytical Prediction of Ground Movements due to a Nonuniform Deforming Tunnel

Experimental study on the damage mechanism of tunnel structure suffering from sulfate attack

Cyclic and post-cyclic shear behavior of low-plasticity silt with varying clay content

A Slurry Consolidation Approach to Reconstitute Low-Plasticity Silt Specimens for Laboratory Triaxial Testing

Changes of Atterberg limits and electrochemical behaviors of clays with dispersants as conditioning agents for EPB shield tunnelling