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Frank R. Lloyd is the associate dean of executive education at Southern Methodist University's Cox School of Business, where he is responsible for programs for executives, managers, and working professionals. Previously, he served as vice president of executive education at the Thunderbird School of Global Management, and as a human resources management executive at General Motors. Lloyd was a Fulbright lecturer at the University of Isfahan in Iran and a United States Information Agency curriculum consultant for Germany. He holds an undergraduate degree from Occidental College, a master's degree from Purdue University, and a PhD degree from the University of Iowa.
Fereshtenejad, Sayedalireza (Seoul National University) | Song, Jae-Joon (Seoul National University) | Afshari, Mohammad Karim (Islamic Azad University) | Bafghi, Alireza Yarahmadi (Yazd University) | Laderian, Asghar (Arak University) | Safaei, Homayon (University of Isfahan)
Abstract The first step to determine mechanical and hydraulic properties of rock masses is the evaluation of geometrical characterizations of discontinuities. Discrete Fracture Network models have been developed to model the geometrical properties of discontinuities. Among all the discontinuity properties, shape is the most controversial. In previous Discrete Fracture Network models, discontinuities were considered as planar surfaces while in some fields, curve-shaped discontinuities could be observed. Folding is the most common factor in the creation of curve-shaped discontinuities in mines and engineering works. In this research, a practical 3D geometrical method has been introduced to model folded layers using Fourier analysis and Spline function. Based on the proposed method, a practical MATLAB script named RocFold was developed. Finally, to evaluate the applicability and the feasibility of the proposed model and script, a typical folded structure in Anjire lead and zinc mine in Isfahan province, Iran was applied. 1 Introduction Discrete Fracture Network (DFN) models have been developed to model the geometrical properties of discontinuities by statistical values and distributions of these characteristics evaluated from analysis of core logging and outcrops mapping. Different conceptual models are applied to build DFN models, and each of them is based on specific relationships between characteristics such as location of fracture, termination, and fracture shape. The earliest model developed to represent fracture systems was based upon the assumption that all fractures can be defined by three sets of unbounded orthogonal fractures (Dershowitz & Einstein 1988). The basic model defined by Snow (1965) consists of orthogonal sets of parallel-unbounded fractures, with a constant spacing between the fractures within each set. Baecher disk model (disk-shaped discontinuities) has been developed by Baecher et al. (1977) and Barton (1978) simultaneously and was one of the first well-characterized discrete fracture models. The ordinary Baecher model has been further on developed to account for fracture terminations at intersections with pre-existing fractures and for more general fracture shapes (Geier et al. 1989 and Dershowitz et al. 1998). Veneziano (1978) introduced a method for adaptation of the concept of Poisson plane fractures to bounded fractures (Veneziano model). Dershowitz (1984) remedied the disadvantage of the Veneziano model that fracture intersections and fracture edges do not coincide. Other than the mentioned models, some other practical conceptual models have been proposed for the modeling of fracture network, such as geostatistical and fractal models.
Ghazvinian, Abdolhadi (Rock Mechanics Engineering Group, School of Engineering, Tarbiat Modares University) | Nejati, Hamid Reza (Rock Mechanics Engineering Group, School of Engineering, Tarbiat Modares University) | Hadei, Mir Raouf (Rock Mechanics Engineering Group, School of Engineering, Tarbiat Modares University)
ABSTRACT: Historical reports indicate that underground structures have different behaviors against earthquake with the same magnitude. This finding infers that the earthquake magnitude alone is not sufficient for determination of earthquake intensity. In other words, peak ground acceleration (GA) that was calculated by attenuation relations is not enough criteria for determination of "design base earthquake" time history because, in addition to GA, seismic loads frequency affect on the earthquake intensity. The aim of this study is to evaluate the effect of seismic load frequency on the behavior of underground structures. For this purpose, effective parameters on the frequency content of seismic loads were identified and two time histories with different frequency content were compiled. Further, Isfahan-Shiraz tunnel, a railway tunnel in southern part of Iran, located in a disturbed zone was analyzed for two separate time histories that have the same GA and different frequency content. These analyses reveal that the frequency content of seismic load has significant effect on the earthquake load energy, stress distribution and underground structure stability. Furthermore, loads with higher frequency attenuate faster whereas, generally, loads with low frequency influence more, to compare with high frequency loads, on the structure stability. 1. INTRODUCTION Underground facilities are an integral part of the infrastructure of modern society and are used for a wide range of applications, including subways and railways, highways, material storage, and sewage and water transport . Underground facilities built in areas subject to earthquake activity must withstand both seismic and static loading. Historically, underground facilities have experienced a lower rate of damage than surface structures. Nevertheless, some underground structures have experienced significant damage in recent large earthquakes, including the 1995 Kobe, Japan earthquake, the 1999 Chi-Chi, Taiwan earthquake and the 1999 Locale, Turkey earthquake . Prediction of ground motions resulting from earthquake is very difficult and it is almost impossible to determine characteristic of ground motion until earthquake actually occurs. Every earthquake causes some unique motions the characteristics of which depend on several factors including disruption mechanism of fault at earthquake source, the wave's propagation media and geological features of earthquake site. Disruption mechanism of fault is complicated and the nature of energy transfer between earthquake source and structure is indeterminate therefore, investigation on all of ground motion characteristics is not possible for common engineering application . For this reason, probable earthquake magnitude is the only parameter used for earthquake risk evaluation for a given special region. Whereas, the effect of seismic load frequency is not considered. It should be noted that the frequency does not play an important role in assessing the shear strength of intact rocks, as shown by Burden , Jamison and Kim  and Ray et al. . Further, Chen Fang et al.  considered the dynamic response and failure behavior of rocks subjected to dynamic loading with the frequency ranging from 0.5 to 5 Hz and found that the obtained strain rate increase with the increase of load frequency.
Shafiei, A. (Earth & Environmental Sciences, University of Waterloo ) | Dusseault, M.B. (Earth & Environmental Sciences, University of Waterloo) | Rahdar, H. (Peymab Construction Company) | Mesgarzadeh, S. (Peymab Construction Company)
Abstract The Dez-Qomroud Tunnel Project lot No. 6 is situated along the Zagros Mountains in west-central Iran. A comprehensive engineering geological study was conducted to determine geomechanical characteristics of the rock masses along the tunnel route. Rock mass classification systems such as rock mass rating (RMR), Q-tunneling index, rock quality designation (RQD), geological strength index (GSI) and rock mass index (RMi) were all employed to classify and characterize the rock masses in order to provide a basis for estimating deformation and strength properties, to supply quantitative data for the design engineering team, and to provide a platform for communication between exploration, design and construction groups. Results obtained from applying different rock mass classification systems for the different rock masses exposed at the QTP6 tunnel path are shown and interpreted in this article. 1. Introduction Supplying sufficient water for both drinking and irrigation purposes to vast arid areas in central Iran that have limited local supplies is one of the great challenges that the Iranian water supply industry faces. The Dez-Qomroud water tunnel project will convey water from the adjacent Dez Highlands to a central Iran watershed known as Qomroud in order to address these needs; it involves four tunnels (total 50 km), three small dams and a large dam. The Qomroud Tunnel Project lot No. 6 is situated along the Zagros Mountains in west central Iran. The tunnel depth (overburden thickness) ranges from 20 to 165 meters. Comprehensive engineering geo-logy and rock mechanics studies were conducted in the study area to assess the geologicalgeomechanical characteristics of the rock masses along the tunnel route. Based on geotechnical drilling reports, the main stratum along the tunnel is a weak mud-supported conglomerate: the Bakhtiari conglomerate formation. The physical and geomechanical properties of the conglomerate exposed in the study area were determined in the laboratory based on ASTM standards and ISRM suggested methods. In order to characterize the rock masses along the tunnel axis, rock mass classification systems such as rock mass rating (RMR), Q-tunneling index, rock quality designation (RQD), geological strength index (GSI) and rock mass index (RMi) were employed to classify and characterize the rock mass. The goals were to provide a reliable and proper basis for estimating deformation and strength properties, to supply quantitative data to design engineers, and to provide a quantitative platform for communication between exploration, design and construction groups. The rock mass constants mb, s and a, GSI values, uniaxial compressive and tensile strengths, cohesion and internal friction angle, global strength and the Young's modulus of this rock mass at the tunnel site were determined from GSI values using RocLab freeware. Results obtained from different rock mass classification systems for the conglomerate rock mass are shown and interpreted in this article. 2. Geological Setting The Qomroud water Tunnel Project lot No. 6, known as QTP6, is a nearly 1.80 km long tunnel, located 45 km south of the Aligoudarz-Isfahan 500 road (Fig. 1).
Hashemi, M. (Department of Geology, Faculty of science, Isfahan University) | Rahman-Nezhad, R. (Mining Engineering Department, Shahid Bahonar University) | Saiedtarrah, B. (Mining Engineering Department, Shahid Bahonar University)
ABSTRACT The twin tunnels for Isfahan subway are being excavated in both soil (alluvial deposits) and rock mass (shale, slate and sandstone). Due to time different between the excavations of the tunnels, it was necessary to simulate how the effect of time and distance lag in excavation of tunnels may affect the surrounding environment in the shape of the ground settlements. An instrumentation monitoring program is also being implemented in the site. The current research work discusses how the results of numerical simulation could show the effect of the distance between the tunnels, and the delay in excavation of tunnels as compared to instrumentation results. Also the area around the tunnels affected by the tunnel face is investigated. 1 INTRODUCTION To resolve the traffic jams, the underground train (subway) is the first solution. Among the various methods for the construction of the subway tunnels, the New Austrian Tunneling Method (NATM) is the most favorite option for the rock mass. The following are also the most important points for successful design & construction of the tunnels using the method:Proper analysis of the tunnel stability under the temporary condition for the ground layers properties nearby the tunnels. The proper estimation of the loading and design of temporary support and its proper installation (Mair & Taylor 1996). The ground settlements due to the tunnel excavation and its effect on surrounding buildings. The latter point (settlement) is the most important factor in success of the tunneling in metropolitan areas which should always be monitored and kept under control (Atkinson 1977). 2 THE ISFAHAN TWIN-TUNNEL SUBWAY PROJECT The 1st phase of the project extends from KavehAve. to Sofeh Bus Terminal with the length of 12 Km.ATBM is being used to excavate the alluvial part starting from KavehAve. toZayanderud riverbed. The southern part mostly consisting of rock mass is being excavated by road header including the 1st segment from Azadi square to Koleini Ave. crossing. In this segment, out of 7m diameter, the 5.1m height is being excavated as heading and the left 1.9m as benching with a time lag. The current research work discusses the effect of excavation faces' distance on the ground surface settlement. The rock mass includes various types of lithologies but mostly consists of sequence of shales and sandstones.To facilitate the calculation and modeling process, an equivalent rock mass called as Jssh has been used.The strength properties of the Alluvial and rock mass layers are presented in Table 1 (Zaminfanavaran 2004). The rock mass properties are derived by Geological Strength Index (GSI) method proposed by Hoek et al. (2002) (Sazbonpajoh 2004). The current research work is intended to investigate the effect of the excavation of twin tunnels with time difference on the surrounding environment using the ground surface settlement as a control parameter. 3 MODELING PROCESS & INPUT DATA The subway twin tunnels are being excavated with time difference.
Abstract Triaxial tests were conducted on the schist specimens with various anisotropic angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strains, were measured and plotted for various conditions. The results obtained reveal the effects of schistose on the strength and deformability of the rock very clearly. Peak strength of the specimens for 0° and 90° schistose orientations are nearly the same. Modulus of elasticity of this rock varies with anisotropic angle. For 0 orientation modulus of elasticity increases to a maximum. Confining pressure increases the peak strength and improves the rock deformability. However, this effect is not the same for various orientations, and there are no similar trends for each anisotropy direction. Analysis of the results shows that consideration of a linear failure criterion such as Mohr-Coulomb is appropriate for the prediction of rock behaviour up to 10 MPa, rather than a non-linear one. The analysis also reveals that the friction angle and cohesion are affected by the anisotropy orientation, and this effect is more important for the cohesion than the friction angles. Resume Les esseys triaxiales sur les echantillon d un roch schist avec les differents angles non-isotrop sous les tension lateral zero et sept et qoinze mega pascal (mpa) est fait et les covtraite et allongment unitaire sont mesure et leur curues est destine sous different condition les resultats obtenues montre les effets du schistosite sur le resistance et le ductilite vissiblement. Le resistance final sur les echantilions pour les angles o degre et 90 degree est equivalent. Le modoule d elasticite de ce roch sera difere par a port de l angle de stratification. Pour l angle o degree le valeur de modoule est le maximum. le pousse lateral augmenterai le resitance final, et sera amilterai le toleran le de ductilite. Mais cette effet bn est pas unigue pour les different stratification, et pour les diferents directions no- isotrop it n y a pas le meme solution. L analyse des resulitats montre que le criterre de ruin comme mohr-colomb est moderate pour le pousse lateral jusq av lo mega pascal, et ce n est pas neccesaire d utiliser de criterre no-linear. Abriß Dreiachsige Pruefung wurde auf den schist Exemplaren mit verschiedenen anisotropic Winkeln unter Bestatigen von Druecken von 0.7 und 15 MPa geleitet, und axiale Spannung axiale Spannungen, wurden gemessen und fuer verschiedene Bedingungen wurde geplant. Die Ergebnisse haben die Wirkungen von schisocity auf der Kraft und dem deformability des Felsen sehr deutlich erhalten offenbart. Maximale Kraft der Exemplare fuer 0° und 90 sind° schistos Orientierungen beinahe das gleiche. Modulus der Elastizitat von diesem Felsen andert sich mit anisotropic Winkel. Fuer 0° vermehrt Orientierung modulus der Elastizitat zu einem Maximum. Einschrankender Druck vermehrt die maximale Kraft und verbessert den Felsen deformability. Aber ist diese Wirkung nicht das gleiche fuer verschiedene Orientierungen, und es gibt keine ahnlichen Tendenzen fuer jede anisotropic Richtung. Analyse der Ergebnisse zeigt jener Überlegung Kriterium eines linearen Ausfalls wie zum Beispiel Mohr Coulomb passend fuer die Voraussage von Felsen Verhalten bis zu 10 MPa, anstatt eines nicht linear ist. Die Analyse offenbart auch, daß der Reibung Winkel und Bindekraft werden beeinflußt von der anisotropic Orientierung, und diese Wirkung wichtiger fuer die Bindekraft ist, als der Reibung Winkel Introduction Rock masses are rarely homogeneous, isotropic and intact, as commonly assumed for other engineering materials (Serafim, 1966). Failure of rock masses, particularly near the surfaces, usually results from sliding along a single discontinuity or a combination of discontinuities (Farmer, 1983). In most parts of the city of Isfahan in Iran, at a depth of 5 to 20 meters from the ground surface, schist is the predominant rock. Determination of the strength properties of this rock is of paramount interest, because many large factories, dams, conveyance tunnels, airports, and heavy buildings are under study and construction. For the purpose of measuring strength and deformation properties of this rock, triaxial tests were conducted on the specimens with various anisotropy angles under confining pressures of 0, 7 and 15 MPa, and axial stress-axial strain were measured and plotted for various conditions. The procedure used for preparation of test specimens was in accordance with the ISRM suggested methods (Brown, 1986). The specimens were cored to a nominal diameter of 45 mm and length of 90 mm. They were smooth and free of any abrupt irregularities, with sides parallel to each other to within 0.01 mm and at right angles to the longitudinal axis.