Development of advanced numerical models for grey cast iron tunnel linings
File(s)
Author(s)
Ruiz Lopez, Agustin D.
Type
Thesis or dissertation
Abstract
Many of the tunnels in the London Underground network are lined with bolted grey cast iron (GCI) linings. In a context where the underground space surrounding these
tunnels is continually being occupied by new geotechnical structures, the evaluation of their response to nearby construction is a problem of significant relevance. However, current methods of structural analysis are limited in accounting for the bolted tunnel joints and how these influence the overall tunnel lining response. This thesis focuses on the development of new tools for the structural assessment of GCI tunnel linings by means of numerical analysis.
A 3D segmental ring model simulating a laboratory set-up is developed first. It incorporates a constitutive model adapted for the simulation of GCI behaviour. The competence of the 3D numerical model is demonstrated via a thorough validation against laboratory data.
A parametric study using a similar 3D model that replicates the assumptions of the elastic continuum model (ECM) is then conducted. The differences between the numerical
model and the ECM allow a set of bending stiffness reduction factors to be derived. These can be applied in routine engineering calculations.
A new joint model for structural elements is proposed. Unlike existing models, it considers the contribution of the joint bolts and the progressive stiffness decay from joint
opening. The model parameters are calibrated to reproduce the joint response as given by the 3D model. The validation procedure demonstrates that results from 2D analyses of the ECM using the new joint model are equivalent to those from 3D analyses.
Finally, the present-day condition of a prototype GCI tunnel is investigated with 2D geotechnical analysis. The impact of the new joint model is demonstrated by comparison
with other modelling approaches. Additionally, the influence of various soil parameters and tunnel drainage conditions on the tunnel response is investigated.
tunnels is continually being occupied by new geotechnical structures, the evaluation of their response to nearby construction is a problem of significant relevance. However, current methods of structural analysis are limited in accounting for the bolted tunnel joints and how these influence the overall tunnel lining response. This thesis focuses on the development of new tools for the structural assessment of GCI tunnel linings by means of numerical analysis.
A 3D segmental ring model simulating a laboratory set-up is developed first. It incorporates a constitutive model adapted for the simulation of GCI behaviour. The competence of the 3D numerical model is demonstrated via a thorough validation against laboratory data.
A parametric study using a similar 3D model that replicates the assumptions of the elastic continuum model (ECM) is then conducted. The differences between the numerical
model and the ECM allow a set of bending stiffness reduction factors to be derived. These can be applied in routine engineering calculations.
A new joint model for structural elements is proposed. Unlike existing models, it considers the contribution of the joint bolts and the progressive stiffness decay from joint
opening. The model parameters are calibrated to reproduce the joint response as given by the 3D model. The validation procedure demonstrates that results from 2D analyses of the ECM using the new joint model are equivalent to those from 3D analyses.
Finally, the present-day condition of a prototype GCI tunnel is investigated with 2D geotechnical analysis. The impact of the new joint model is demonstrated by comparison
with other modelling approaches. Additionally, the influence of various soil parameters and tunnel drainage conditions on the tunnel response is investigated.
Version
Open Access
Date Issued
2022-03
Online Publication Date
2024-09-30T23:01:21Z
2024-10-28T10:56:08Z
Date Awarded
2022-10
Copyright Statement
Creative Commons Attribution NonCommercial Licence
Advisor
Standing, Jamie
Tsiampousi, Aikaterini
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/R512540/1
Publisher Department
Civil and Environmental Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)