Numerical Evaluation of Symmetric Prism Method to Analyze the Splitting Forces Due to TBM Jack Loads

Hamid Saberi,Ashkan Firouzi,Ali Kheyroddin,Vahid Saberi

doi:10.4236/ojsst.2013.33006

Hamid Saberi, Ashkan Firouzi + Show 2 more

Open Access

https://doi.org/10.4236/ojsst.2013.33006

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Abstract

Final lining in mechanized excavation includes the precast concrete segments. These segments are designed for applied loads during construction, moving, depot, assembling in the tunnel and service loads that are affected by earth conditions. One of these loads that are applied to the segments after assembling in the ring, are TBM jack loads especially when the TBM should excavate squeeze zones with single mode. As the jack pad section is smaller than the segment section, it causes splitting loads in the segment. Symmetric prism method is an approximate solution to evaluate these forces. In this paper, calculated results by this method are compared to that of numerical solution by ANSYS software. It shows 10 - 20 percent difference between numerical and analytical results.

Highlights

Final lining in mechanized excavation includes the precast concrete segments. These segments are designed for applied loads during construction, moving, depot, assembling in the tunnel and service loads that are affected by earth conditions. One of these loads that are applied to the segments after assembling in the ring, are Tunnel boring machine (TBM) jack loads especially when the TBM should excavate squeeze zones with single mode
As the jack pad section is smaller than the segment section, it causes splitting loads in the segment
Calculating the Transverse Tensile Loads (Tb2) Along Longitudinal Direction of the Segment (Section A-A). This load is equal to 23 tons in accordance with symmetric prism pattern that longitudinal reinforcements are controlled within transverse range 0.2Le-Le (i.e. 20 - 96 cm) to carry the load

Summary

Introduction

Final lining in mechanized excavation includes the precast concrete segments. The carrying loads of each jacks to move forward the TBM at the normal mode is estimated 50 tons at water tunnels having conventional excavation diameters equal to 4.5 meters which will be applied by jack thrust to precast lining thickness along tunnel. Considerable compressive loads are required to move the TBM at the critical cases which estimated 1550 tons for TBM jacks. These loads are contributed within ten cylinders and are applied to segments by pads.

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