Abstract. The world of underground engineering and construction has acquired a wide-ranging and high-level experience on tunnel construction with Tunnel Boring Machines (TBM) and nowadays remarkable progresses are traceable in the number of tunnels that are becoming longer, going deeper, and growing larger in diameter and in other words becoming more difficult to realize. Tabriz-one of the big cities in northern west of Iran has four subway lines which are under construction or investigation. The phase1 design of Tabriz urban railway line 2 (TURL2) has completely been done. Method statement of this line in the length of about 20 km and much interference due to tunneling in urban area dictates the application of TBM. Two kinds of TBM such as EPB (earth pressure balance) and SS (slurry shield) are usually used for urban areas. In this paper, the process of choosing TBM for TURL2 using MCA method (Multi Criteria Analysis) is expressed. Generally in this method some technical, economical and environmental parameters affected the TBM type are identified and taken into account by assigned weights related to the case study. Finally the results show that EPB-TBM will be more appropriate choice for TURL2 excavation.
Deterministic code-based designs proposed for wind turbine foundations are typically biased on the conservative side, and overestimate the probability of failure, which can lead to higher than necessary construction cost. In this study reliability analysis of a gravity-based foundation, concerning its bearing capacity, is used to calibrate a code-based design procedure. A probabilistic finite-element model is developed to analyse the bearing capacity of a surface footing on soil with spatially variable undrained strength. Monte Carlo simulation is combined with a re-sampling simulation technique to perform the reliability analysis. The calibrated code-based design approach leads to savings of up to 20% in the concrete foundation volume, depending on the target annual reliability level. The study can form the basis for future optimisation on deterministic-based designs for wind turbine foundations. This paper is subject to British Crown Copyright.Ã L ¼ 85 m is the height of wind turbine, see Table 1. Therefore, M and H are fully correlated. † The vertical load is a function of foundation radius, R (m), and weight of the wind turbine. Rough values of 2 m for the foundation height and 14 kN/m 3 for the foundation submerged unit weight are considered. 636 VAHDATIRAD, GRIFFITHS, ANDERSEN, SØRENSEN AND FENTON
The mechanical responses of an offshore monopile foundation mounted in over-consolidated clay are calculated by employing a stochastic approach where a nonlinear p-y curve is incorporated with a finite element scheme. The random field theory is applied to represent a spatial variation for undrained shear strength of clay. Normal and Sobol sampling are employed to provide the asymptotic sampling method to generate the probability distribution of the foundation stiffnesses. Monte Carlo simulation is used as a benchmark. Asymptotic sampling accompanied with Sobol quasi random sampling demonstrates an efficient method for estimating the probability distribution of stiffnesses for the offshore monopile foundation. tcem interests include reliability analysis in geotechnical engineering, design of offshore foundations, computational methods, soil liquefaction, mechanized tunnelling, soil improvement.
Upper Gotvand Dam is constructed on the Karun River at the south west of Iran. In this paper, 2D and 3D models of the dam together with the foundation and abutments were established, and several seepage analyses were carried out. Then, the gypsum veins that are scattered throughout the foundation ground were included in the models, and the seepage pattern, considering the dissolution law of gypsum, was analyzed. It was disclosed that the discharge fluxes obtained from 2D and 3D analyses are not similar, and the discharge flux in 3D model is about four times that of the 2D model. Also, the 3D model locates the phreatic surface somewhat higher than the 2D model. This means that the 2D model estimates lower pore water pressure pattern in comparison with the 3D model. These may be attributed to the fact that with 2D model the lateral components of vectors of seepage velocity are ignored. In the current case, the rate of increase of discharge flux due to dissolution of gypsum veins was obtained to be a thirdorder function of the aperture width. In spite of the fact that the grout curtain is designed to be about 170 m deep, however, complete dissolve of gypsum will severely increase the discharge flux through the foundation ground.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.