Dr C Paraskevopoulou
Dr D Connolly
Dr Peter Woodward
Dr M Hildyard
Thursday, January 31, 2019
Competition Funded PhD Project (UK Students Only)
This project will be of interest to someone looking for a multidisciplinary project involving fieldwork, laboratory analysis and numerical modelling in the broad areas of tunnelling, geotechnical and geological engineering. The research will place the successful candidate in an ideal position to gain future employment in industry or academia.
The demand for fast commuting between densely populated cities has increased over the last 30 years. This is evident with the existence of high-speed railway lines mainly in central Europe where within in 2 hours you can travel 500 – 600 km. The need of such infrastructures has risen along with the technological advancement and the environmental advantage to cars and social benefits that encounters. The latter implies that the number of railway tunnels connecting (remote) areas faster due to topographical limitations has also risen. One of the key considerations on railways tunnels especially high speed lines is the propagation of vibrations generated as the train(s) passes through. Although significant scientific progress has been made on investigating and analyzing on the ground vibrations from high speed rail lines (Connolly et al. 2013; 2015; 2016), it focuses commonly on embankments and soils. There is a gap of scientific knowledge in tunneling environment where the vibrations propagate from the tunnel support to the surrounding rock or ground. The proposed project aims to develop a better understanding of the tunnel behaviour due to the initiation and propagation of vibrations induced in high speed railways. As different rocks (rock masses) and different types of ground behave in different ways when subjected to dynamic loading, especially over time. One of the main factors controlling their mechanical behaviour is geology and more specifically the mineralogical content and its structural characteristics (Paraskevopoulou, 2016, et al. 2017, 2018). The wave propagation path (causing vibrations) is directly influenced by the latter, as it depends on the discontinuities (joints, faults etc), elements of weaknesses (shear zones, geological contacts etc) on the geological setting and fracture stiffness (Hildyard, 2007). Being able to predict the tunnel system’s reaction can be paramount of importance especially for the system’s lifetime and therefore its resilience. The project will involve field work, experimental testing on physical models as well numerical analyses using finite-element, finite-difference, distinct-element methods towards in developing practical tools and models that can find use not only in the field of research but also use not only in the field of research but also in industry is of utmost importance.
AIMS AND OBJECTIVES
The main aim is to develop a better understanding of the tunnel behaviour due to the initiation and propagation of vibrations induced in high speed railways. objectives include:
• Developing constitutive relationships to describe the mechanical behaviour of the tunnel (ground-support) system
• Gaining understanding of how the vibration-induced mechanisms can affect the mechanical behaviour on a range of time-scales.
• Assessing the implications of these results for issues such as closure of fractures, long-term stability of tunnels.
These objectives will be met with the help of state-of-the art laboratory facilities and numerical modelling software.
The proposed research project aims to investigate the mechanical behaviour of the complete tunnel system (ground-support) by performing a number of laboratory testing at Rock Mechanics, Engineering Geology and Geotechnical Laboratory (RMEGG) at University of Leeds Geotechnical (RMEGG): http://www.see.leeds.ac.uk/business-and-consultation/facilities/engineering-geology-laboratory/
Numerical analyses using finite element, finite difference and distinct-element methods combined with big data analysis methods will be performed to develop a constitutive model.
Up to 3.5 years, subject to satisfactory progress, to include tuition fees (£4,400 for 2018/19), tax-free stipend (£14,777 for 2017/18), and research training and support grant. Eligibility is UK and those EU who meet the UK 3 years residence requirement immediately preceding the commencement of the PhD.
• Connolly DP; Kouroussis G; Woodward PK; Giannopoulos A; Verlinden O; Forde MC (2014) Scoping prediction of re-radiated ground-borne noise and vibration near high speed rail lines with variable soils. Soil Dynamics and Earthquake Engineering, 66 , pp. 78-88.
• Connolly DP; Marecki GP; Kouroussis G; Thalassinakis I; Woodward PK (2016) The growth of railway ground vibration problems — A review. Science of The Total Environment, 568, pp. 1276-1282.
• Connolly DP; Kouroussis G; Laghrouche O; Ho CL; Forde MC (2015) Benchmarking railway vibrations – Track, vehicle, ground and building effects. Construction and Building Materials, 92, pp. 64-81.
• Hildyard MW. 2007. Manuel Rocha Medal Recipient - Wave interaction with underground openings in fractured rock. ROCK MECH ROCK ENG. 40(6), pp. 531-561.
• Paraskevopoulou, C. 2016. Time-dependency of rock and implications associated with tunnelling, PhD Thesis. In: Queen’s University Publications. Canada.
• Paraskevopoulou, C., Diederichs, M., 2018. Analysis of time-dependent deformation in tunnels using the Convergence-Confinement Method. Tunnelling and Underground Space Technology,17, 62-80. (http://dx.doi.org/10.1016/j.tust.2017.07.001)
• Paraskevopoulou, C., Perras, M., Diederichs, M.S., Löw, S., Lam, T., Jensen., M. Time-dependent behaviour of brittle rocks based on static load laboratory testing. Journal of Geotechnical and Geological Engineering, 36, 337(DOI 10.1007/s10706-017-0331-8)
• Paraskevopoulou, C., Perras, M., Diederichs, M.S., Löw, S. 2017. The three stages of stress-relaxation - Observations for the long-term behaviour of rocks based on laboratory testing. Journal of Engineering Geology, 216, 56-75. (http://dx.doi.org/10.1016/j.enggeo.2016.11.010)
How good is research at University of Leeds in Earth Systems and Environmental Sciences?
FTE Category A staff submitted: 79.20
Research output data provided by the Research Excellence Framework (REF)
Click here to see the results for all UK universities