H. Dehghani; N. Mikhak Beiranvand
Abstract
One of the most important parameters used for determining the performance of tunnel boring machines (TBMs) is their penetration rate. The parameters affecting the penetration rate can be divided in two categories. The first category is the controllable parameters such as the TBM technical characteristics, ...
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One of the most important parameters used for determining the performance of tunnel boring machines (TBMs) is their penetration rate. The parameters affecting the penetration rate can be divided in two categories. The first category is the controllable parameters such as the TBM technical characteristics, and type and geometry of the tunnel, and the second one is the uncontrollable parameters such as the intact rock properties and characteristics of the rock mass discontinuities. The aim of this work was to investigate the effects of rock mass properties on the penetration rate, and to present a new mathematical equation based on a statistical approach to estimate the TBM performance. To achieve this aim, the Monte-Carlo (MC) simulation method was used to model the TBM performance. Accordingly, the database consisting of the rock mechanics information such as the uniaxial compressive strength, Brazilian tensile strength, toughness and hardness of rock, spacing and orientation of discontinuities, and measured TBM penetration rate in 151 points out of a water tunnel was collected. Next, using the dimensional analysis, a comprehensive mathematical equation was obtained to calculate the TBM penetration rates using the developed database. Finally, using the MC simulation method, the probability distribution function of the TBM penetration rate was studied. The validation results obtained showed that the root mean square error (RMSE) of the proposed relationship was less than 0.3. The MC simulation results showed that hardness and density had the most and least effects on the penetration rate, respectively.
M. Filbandi Kashkouli; A. Kamkar Rouhani; Ali Moradzadeh; H. Assi
Abstract
Magnetotelluric (MT) method is an electromagnetic technique that uses the earth natural field to map the electrical resistivity changes in subsurface structures. Because of the high penetration depth of the electromagnetic fields in this method (tens of meters to tens of kilometers), the MT data is used ...
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Magnetotelluric (MT) method is an electromagnetic technique that uses the earth natural field to map the electrical resistivity changes in subsurface structures. Because of the high penetration depth of the electromagnetic fields in this method (tens of meters to tens of kilometers), the MT data is used to investigate the shallow to deep subsurface geoelectrical structures and their dimensions. In order to have a higher accuracy in modeling the MT data, dimensions of the subsurface structures should be determined. The objective of this research work is to determine the dimensions of subsurface structures in an oil field located in the southwest of Iran. Using parameters such as the normalized weighted index, ellipticity, and Wall's rotational invariant measure, this goal could be achieved. Using the ellipticity factor at the frequency range of 1-320 Hz, the earth can be represented as a 2D form. However, at lower frequencies, the earth should be represented as a 3D form. In most MT stations, the normalized weighted index has indicated that the earth is in a 2D form on the surface or shallow subsurface, although it is represented by a 3D shape at higher depths. In this regard, the Wall's rotational invariant measure shows more heterogeneity. This measure indicates that the earth is in the 2D and 3D forms on the surface or shallow subsurface, and is perfectly 3D at higher depths, although the earth dimensions cannot be determined in some certain frequency ranges. The earth in both the shallow and deep parts of the studied area has a high heterogeneity.
