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    Analysis of support requirements for a shallow diversion tunnel at Guledar dam site, Turkey
    (Elsevier, 2005) Basarir, H; Ozsan, A; Karakus, M
    Engineering geological properties and support design of a planned diversion tunnel at Guledar dam site, which was located at the North of Ankara, Turkey were studied in this article. The main purpose of the construction of the planned tunnel is to regulate, drainage and to provide water for irrigation purposes. The diversion tunnel runs mainly through formations of limestone, sandstone and diabase. Rock masses at the site were characterized using Rock Mass Rating (RMR), Rock Mass Quality (Q), Rock Mass Index (RMi) and Geological Strength Index (GSI). RMR, Q, RMi and GSI were determined by using field data and mechanical proper-ties of intact rock samples, measured in the laboratory. Support requirements for the planned diversion tunnel were determined accordingly in terms of the rock mass classification systems. Recommended support systems by empirical methods were also analyzed using 2D Finite Element method. Calculated parameters based on empirical methods were used as input parameters in the finite element models. The results from both methods were compared with each other. This comparison suggests that more reliable support design could be achieved by using the finite element method together with the empirical methods. (c) 2005 Elsevier B.V. All rights reserved.
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    Back analysis for tunnelling induced ground movements and stress redistribution
    (Pergamon-Elsevier Science Ltd, 2005) Karakus, M; Fowell, RJ
    Analysing tunnelling process in 2D plane strain conditions is widely used method to calculate tunnelling induced settlement profiles as well as soil structure interactions. Possibility of damage to the surface and/or underground structures can be estimated using powerful finite difference method (FDM) and finite element method (FEM) of analysis. However, setting up a realistic model that would be able to achieve this goal is rather difficult. In this paper, 2D FDM analysis has been conducted to assess tunnelling induced settlement, stress redistribution phenomena along with movements around shallow soft ground tunnels excavated in accordance with the New Austrian Tunnelling Method. Measurements recorded during construction of the Heathrow Express Trial Tunnel in London Clay were compared with the predicted values to validate numerical estimations. As a soil model, the Mohr-Coulomb plasticity model has been used in the FDM analysis. Results obtained from 2D FEM are also included in this paper for comparison purposes to evaluate performance of both numerical analysis procedures. Predictions from both FDM and FEM analyses proved to be procedures used within this work can be a tool in practical engineering applications to simulate tunnelling operations. (c) 2005 Elsevier Ltd. All rights reserved.
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    Effects of different tunnel face advance excavation on the settlement by FEM
    (Pergamon-Elsevier Science Ltd, 2003) Karakus, M; Fowell, RJ
    The excavation process for a tunnel changes in terms of its service requirements, ground conditions and the stability of surface buildings in urban areas. When a tunnel is excavated, there will be settlement, which may cause damage to surface structures. To control and limit the settlement caused by tunnelling operations, there have been many tunnelling techniques proposed. Thus, in this paper, a number of Finite Element Method analyses were conducted to investigate the effects of different patterns for advancing the tunnel face on the settlement. The Heathrow Express Trial tunnel was constructed in accordance with the principles of the New Austrian Tunnelling Method (NATM). The settlement measurements taken during its construction were used to validate the results from the analyses undertaken. Three different face advance techniques were used during the construction of the Heathrow Express Trial tunnel viz. Twin sidewall excavation (TS1), single sidewall excavation (TS2), and Crown, Bench and Invert excavation (TS3). As the trial work proved that TS2 produced the minimum settlement above tunnel centreline, only TS2 was subjected to the FEM analysis in this research. In order to simulate TS2 correctly three types of excavation models were devised and the results compared to field measurements of TS2. For the FEM analysis the Hypothetical Modulus of Elasticity (HME) soft lining approach was used and a practical method to estimate HME is proposed for when it is used for different face advance sequences. Results proved that when the excavation pattern was changed, the HME value was also changed and settlement over the tunnel centreline changed in terms of the face advance pattern adopted. (C) 2003 Elsevier Science Ltd. All rights reserved.
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    Fuzzy and multiple regression modelling for evaluation of intact rock strength based on point load, Schmidt hammer and sonic velocity
    (Springer Wien, 2006) Karakus, M; Tutmez, B
    Uniaxial Compressive Strength (UCS), considered to be one of the most useful rock properties for mining and civil engineering applications, has been estimated from some index test results by fuzzy and multiple regression modelling. Laboratory investigations including Uniaxial Compressive Strength (UCS), Point Load Index test (PL), Schmidt Hammer Hardness test (SHR) and Sonic velocity (V-p) test have been carried out on nine different rock types yielding to 305 tested specimens in total. Average values along with the standard deviations (Stdev) as well as Coefficients of variation (CoV) have been calculated for each rock type. Having constructed the Mamdani Fuzzy algorithm, UCS of intact rock samples was then predicted using a data driven fuzzy model. The predicted values derived from fuzzy model were compared with multi-linear statistical model. Comparison proved that the best model predictions have been achieved by fuzzy modelling in contrast to multi-linear statistical modelling. As a result, the developed fuzzy model based on point load, Schmidt hammer and sonic velocity can be used as a tool to predict UCS of intact rocks.
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    Predicting elastic properties of intact rocks from index tests using multiple regression modelling
    (Pergamon-Elsevier Science Ltd, 2005) Karakus, M; Kumral, M; Kilic, O
    [Abstract Not Available]
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    Predicting horizontal movement for a tunnel by empirical and FE methods
    (Kozan Ofset Malbaacilik San Vetic Ltd Sti, 2001) Karakus, M
    There are a number of benefits in constructing transport tunnels in highly populated areas for relieving traffic congestion and increasing the speed of travel for commuters, Instead of constructing a single tunnel, multiple tunnels constructed side by side offer more benefits. However, to avoid any adverse effects of tunnels on one another, more attention should be given to estimation of, horizontal movement, which will ease not only support design, but also help to determine critical regions ard find a tunnel. Thus, a number of Finite Element Methods (FEM) as well as empirical analyses were conducted in this research to estimate horizontal movement profiles for a tunnel. The results of both analyses were compared with field measurements as well as each other. The comparison showed that the empirical models could be used to estimate the far-field settlement profiles, but that they could not be used for the near-field ground response to tunnelling. However, finite element analyses were in very good agreement with not only far-field but also near-field ground response tunnelling.