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Author: search.filters.author.Heama, Narunat

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    INVESTIGATION OF TUNNEL RESPONSE DUE TO THE EFFECT OF ADJACENT LOADED PILE ROW BY 3D SIMULATION ANALYSIS
    (2022-09-01)
    Heama, Narunat
    ;
    Lueprasert, Prateep
    The construction of tunnels for transportation, wastewater, electricity, etc., in the major cities has flourished. In the meantime, other infrastructures such as elevated trains, and flyovers, are continually constructed for urbanization. Under a soft ground condition, they are supported by the pile foundations required pile rows which are possibly located along the existing tunnel. A common challenge encountered in the loaded pile row of the new adjacent structures is inevitably inducing soil stress changes and deformation of existing tunnels. Thus, an assessment of the impact of pile underloading on the integrity of the existing tunnels is essential. The three-dimensional finite element analyses (3D FEA) with two pile conditions were carried out. The tunnel responses (transversal deformation and additional forces) at different transverse sections are presented. The maximum response of those was shown in the monitoring section (center of pile row section). Meanwhile, the torsion deformations are maximum as the 12 – 30 m ( ≈ 1.5Dtunnel - 4.5Dtunnel) away from the center of the pile row. For both short and long pile conditions, the influence zones of loaded pile row in a longitudinal direction are independent of the pile length and extended horizontal distance of 2Dtunnel away from the last pile within a row.
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    Comparative effects of adjacent loaded pile row on existing tunnel by 2d and 3d simulation models
    (2021-10-25)
    Heama, Narunat
    ;
    Jongpradist, Pornkasem
    ;
    Lueprasert, Prateep
    ;
    Suwansawat, Suchatvee
    ;
    Jamsawang, Pitthaya
    Selecting suitable simulation methods for complex problems requires a careful balance between the predicted accuracy and computational effort. This research comparatively investigated the effects of adjacent loaded pile row on an existing tunnel in terms of tunnel deformation and lining force, displacement of soil surrounding between tunnel and pile and load transfer of the pile. Simulations were carried out by eight simulation models consisting of 3D finite element (FE) full models (model 1-2); 3D FE symmetry models (model 3-4); and a pile wall in 2D FE models (models 5-8). In loaded pile row simulation, simulations were performed with two pile types: volume pile and embedded pile. In 2D simulation, the 3D pile row was converted into 2D pile wall under plane strain condition by using three transformation methods. The results show that the predicted tunnel responses are adequately accurate as long as the reasonable soil movement behavior can be reproduced. The 2D equivalent dimensions and 2D equivalent axial rigidity are recommended since they provide conservative estimation on both tunnel deformation and lining forces. The 2D equivalent flexural rigidity is not recommended if the pile response is also of concern. The novelty of this research lies in the use and discussion on the applicability of various 2D and 3D models to simulate the effects of adjacent loaded pile row on the existing tunnel, as opposed to previous studies which focused on one or two simulation models.
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    Investigation on pile-soil-tunnel interaction due to adjacent loaded pile row by 3D FEM
    (2018-08-14)
    Heama, Narunat
    ;
    Jongpradist, Pornkasem
    ;
    Lueprasert, Prateep
    ;
    Suwansawat, Suchatvee
    The effect of adjacent loaded pile row on the existing tunnel is analysed by 3D finite element method. The MRTA project is used as reference case in this study. The case study is divided into two cases, tunnel and pile tip located in soft clay and stiff clay, respectively. The pile diameter of 1 m and pile tip located at the elevation of tunnel crown with various number of piles within the row were considered. The analysis results are shown in terms of total soil displacement (without tunnel) and maximum tunnel deformations. Both total soil displacements and tunnel deformation increase with the number of piles and approach a maximum value when the number of piles is greater than 13 and 11 for cases tunnel in soft and stiff clay, respectively. This reveals that the tunnel deformation mechanism is primarily due to the soil displacement.
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    Investigation on tunnel responses due to adjacent loaded pile by 3D finite element analysis
    (2017-01-01)
    Heama, Narunat
    ;
    Jongpradist, Pornkasem
    ;
    Lueprasert, Prateep
    ;
    Suwansawat, Suchatvee
    Underground structures are popularly utilized in urban development, especially tunnels for both transportation and utilities. The interaction problem between existing tunnel and piles from new constructed structures thus becomes unavoidable in dense population area. The tunnel loses its stability if the additional forces and changed diameters (due to adjacent piles under loading) of tunnel lining are drastically high. This depends on many factors, such as the clearance and pile tip level with respect to tunnel position. For preliminary assessment during the first stage of design, it is necessary to estimate this impact. The concept of tunnel protection zone is commonly adopted. However, to establish the tunnel protection zone for adjacent loaded pile, the understanding on this interaction problem is essential. This study analyzes the effect of adjacent pile under loading on the existing tunnel by 3D finite element method. The case study is the tunnel of MRTA project subjected to an adjacent 1 m bored pile under loading with various lengths and clearances. The additional forces (bending moment and axial force) and the tunnel deformations are investigated. The results show that the additional forces and the tunnel deformations decrease when the clearance increase and become insignificantly increasing when the clearance is larger than 3.5 m. The distribution patterns of additional forces and tunnel deformation are similar.