Bulletin of Engineering Geology and the Environment (14359537)59(3)pp. 195-199
Mudrocks exhibit a variation in compressive strength when the direction of the plane of weakness is varied with respect to the direction of the principal stresses. Uniaxial compression tests were performed on two anisotropic mudrocks (siltshale and mudshale). The sample laminations were at orientation angles of 0, 15, 30, 45, 60, 75 and 90° relative to the direction of loading. The anisotropy strength ratio (the ratio of the maximum compressive strength to the minimum strength) over the full range of the lamination orientations was determined. The results of the uniaxial compressive strength tests were compared with the strength anisotropy index ratio [IS(50)] determined from the point load strength tests. The difference between the anisotropy ratios from the individual point load test results and from the uniaxial compressive test results indicates the difficulty of determining the anisotropy from point load tests.
Waste Management and Research (0734242X)19(3)pp. 257-261
The thermophilic and mesophilic microbiota in compost produced from Esfahan municipal solid waste were examined at different stages of composting process from day zero to 28 days and was conducted in four different seasons. Some of the mesophilic bacteria observed in initial stages of composting process were gram negative Escherichia, Klebsiella, Aeromonas and Alcaligenes, and gram positive Enterococcus and Bacillus species. After 20 days of the composting process lower species diversity of mesophiles (only Bacillus species) were isolated, which was most likely due to the high temperature (60-68°C) condition. Some of the observed thermophilic bacteria at later stages of the process are: Bacillus subtilis, B. polymyxa, B. pumilus, B. sphaericus, and B. licheniformis from thermotolerants, and B. stearothermophilus, B. acidocaldarius, and B. schleglii from thermophiles. Among the mesophilic fungi, at the initial stages of composting process some types of yeasts and molds were isolated, but after day 20 due to high temperature condition (60-68°C), no mesophilic fungi were obtained. On the 15th day of composting the highest diversity of thermo-tolerant fungi such as Cladosporium, Aspergillus, Mucor, Rhizopus, and Absidiae spp. were observed. The results indicated that, in order to obtain a sanitary product in cold seasons, the composting process needs a longer duration and fewer turnings.
Earth and Planetary Science Letters (0012821X)203(1)pp. 93-104
The mantle peridotites of Neyriz record two successive episodes of plastic deformations; the first one related to the igneous accretion of the lithosphere and the second one developed during the first stage of the emplacement of the peridotites. These two events have been distinguished on the basis of microstructural criteria. The diapiric pattern, particularly relevant to the mantle process beneath spreading ridges, features vertical flow lines and elliptic flow plane trajectories in a pipe and extends along the ridge axis about 5 km. These structures rotate to horizontal and diverge in every direction in a narrow transition zone, a few hundred meters thick, below the Moho discontinuity. Such a diapiric pattern has been recognized in a few places along the Neyriz paleo-ridge. A large amount of magma passed through these mantle diapirs that were probably the main zones feeding the overlying magma chamber. The most common pattern features very regular structures over several kilometers along the strike of the paleo-ridge: the flow plane dips away from the ridge axis, and the flow line is parallel to the spreading direction. This flow pattern is frozen during the gradual accretion of the lithospheric mantle away from the ridge in a steady-state spreading regime. A shear-sense inversion at just below the Moho is commonly observed, pointing to forced asthenospheric flow. The reconstructed orientation of the Neyriz paleo-spreading center is 105°, compatible with the geometry and orientation of harzburgite foliations and lineations and sheeted dikes. © 2002 Elsevier Science B.V. All rights reserved.
Ground Water (0017467X)41(5)pp. 602-607
The Theis type curve matching method and the Cooper-Jacob semilog method are commonly used for estimation of transmissivity and storage coefficient of infinite, homogeneous, isotropic, confined aquifers from drawdown data of a constant rate pumping test. Although these methods are based on drawdown data, they are often applied indiscriminately to analyze both drawdown and recovery data. Moreover, the limitations of drawdown type curve to analyze recovery data collected after short pumping times are not well understood by the practicing engineers. This often may result in an erroneous interpretation of such recovery data. In this paper, a novel but simple method is proposed to determine the storage coefficient as well as transmissivity from recovery data measured after the pumping period of an aquifer test. The method eliminates the dependence on pumping time effects and has the advantage of employing only one single recovery type curve. The method based on the conversion of residual drawdown to recovered drawdown (buildup) data plotted versus a new equivalent time (Δt X tp/tp + Δt). The method uses the recovery data in one observation point only, and does not need the initial water level h0, which may be unknown. The accuracy of the method is checked with three sets of field data. This method appears to be complementary to the Cooper-Jacob and Theis methods, as it provides values of both storage coefficient and transmissivity from recovery data, regardless of pumping duration.
Engineering Geology (00137952)68(3-4)pp. 225-236
Site investigation and evaluation of properties of soil or rock are important aspects of geotechnical design. Determination of the ground stiffness is one of the important parameters in geotechnical engineering. Since the measurement of shear modulus is very sensitive to soil disturbance, especially for sand, determination of the stiffness of soil in the field is more reliable than in laboratory tests on sampled specimens. Measurement of shear modulus is one of the most common applications of self-boring pressuremeter testing. As an in situ device, the pressuremeter provides a unique method for assessing directly the in situ shear modulus of a soil. This paper describes a laboratory study of silica sand stiffness, which varies with stress level and strain amplitude. The results show that the elastic shear modulus value is mainly dependent on the value of the mean effective stress and relative density. © 2002 Elsevier Science B.V. All rights reserved.
Ground Water (0017467X)42(1)pp. 2-2
Carbonates and Evaporites (08912556)19(1)pp. 67-74
The Gavkhoni Playa Lake is located to the southeast of Esfahan, Iran. It is surrounded by the Varzaneh aeolian sand field to the west and alluvial/fluvial sediments to all other directions. It is typical of the few permanent lakes within closed drainage basins in Iran. The properties of intermittent fine-grained and coarse-grained siliciclastic and finally fine-grained evaporite sediments suggest that the basin was influenced repeatedly by wet and dry periods. During periods of flooding, it had been a shallow permanent lake. With increasing aridity, the middle of the lake became increasingly restricted and shallower which resulted in the formation of a salt pan, contributing to the nature of the lake brine. Due to the enclosed nature of the lake system, the water chemistry of Gavkhoni Playa Lake is dominated by sodium and chloride ions but shows wide variations in composition and concentration through time and location. The percentage of Na+(1,012 to 10,3040 ppm), Cl(4,118 to 19,9365 ppm), Mg2+ (360 to 25,691 ppm), and K+(78 to 3,570 ppm) is highest toward the south and at a minimum in the north. Calcium content, ranging from 160 to 3,480 ppm, appears highest in the north. The percentage of strontium (5 to 292 ppm) with the highest value to the north, is extremely low in comparison to other elements. Sulfate is another abundant anion in the brines with the highest content of 22,051 ppm. Bicarbonate is a minor anion ranging from 73 to 450 ppm with the highest values to the north and west. The concentration of sulfate and bicarbonate does not change regularly in the brines from north to south, nor does it vary seasonally. The chemical analysis of the brine shows that it becomes progressively depleted in carbonate and sulfates from the margins to the center of the lake. It ultimately became a Na+, (Mg2+), Cl-brine type in the northern section and a Na+, Mg2+, Cl-brine type in the central part of the lake. After complete desiccation, the mineral assemblage exhibited halite, camallite, bischofite, and tachyhydrite in abundance.
Ground Water (0017467X)42(1)pp. 2-2
International Journal of Rock Mechanics and Mining Sciences (13651609)41(SUPPL. 1)
There are various structural and geological stratigraphies in study area. The main lithology includes the shale, marl, limestone and dolomite that belong to the Cambrian to upper Cretaceous besides Quaternary deposits. To identify the engineering and geotechnical characteristics of the rock mass along the tunnel route, the results of laboratory and in situ tests, geophysical explorations (geoelectrical methods), field observations and borehole logging charts have been used. The well-known rock mass classification systems for tunnelling purposes (RMR, GSI and Q-system) have been used. Using the GSI classification system for rock mass, the modified Hock- Brown criterion parameters of the rock mass for typical section were determined. The RMR was used to determine the required support for the entire length of tunnel. Also the Q system was used to compare the required support from Q system with the RMR system. Finally rock-support interaction analysis was conducted for a typical cross section of the tunnel. Using the above empirical and analytical methods, the required supports were compared for a typical section. © 2004 Elsevier Ltd.
Carbonates and Evaporites (08912556)20(1)pp. 34-41
The zeolite deposits in Central Alborz, north of Iran display several features typical of their formation in hypersaline basins. Clinoptilolite, a predominant zeolite mineral in saline, alkaline lake deposits, occurs as a most common zeolite species in the zeolitized tuffs of the study area. Furthermore, the high concentration of chlorine (up to 0/5 wt%) and Sr (>1500 ppm) in zeolite deposits indicate that brackish water has presumably some bearing on the genesis of these deposits in north of Iran.
Carbonates and Evaporites (08912556)20(2)pp. 131-137
An analysis of microfacies features and of larger benthic foraminiferal assemblages which include imperforate and perforate, was used to define microfacies types. The predominant microfacies are; 1) Rudist, orbitoidae wackestone packstone; 2) Rudist packstone; 3) Bioclast grainstone; 4) Orbitoidae, miliolids, bioclast wackestone packstone; 5) Dicyclina, miliolids, bioclast wackestone packstone; 6) Miliolids mudstone; 7) Peloidal, bioclast wackestone packstone; 8) Bioclast, ostracoda packstone grainstone. Three major depositional environments are identified in the Tarbur Formation on the basis of grain types, physical and biogenic sedimentary structures and vertical facies relationships. These include shallow subtidal (shelf lagoon), sand shoal and open marine. Tarbur Formation sediments were deposited on a ramp carbonate platform. Four depositional sequences were also recognized in the Tarbur Formation. TST sediments dominated by hyaline foraminifera and HST sediments dominated by various taxa of imperforate foraminifera. The assemblages of perforate and imperforate foraminifera and microfacies are used for interpretation of palaeoenvironment features of the Tarbur Formation.
Facies (01729179)52(1)pp. 41-51
The Asmari Formation, a thick carbonate succession of the Oligo-Miocene in Zagros Mountains (southwest Iran), has been studied to determine its microfacies, paleoenvironments and sedimentary sequences. Detailed petrographic analysis of the deposits led to the recognition of 10 microfacies types. In addition, five major depositional environments were identified in the Asmari Formation. These include tidal flat, shelf lagoon, shoal, slope and basin environmental settings and are interpreted as a carbonate platform developed in an open shelf situation but without effective barriers separating the platform from the open ocean. The Asmari carbonate succession consists of four, thick shallowing-upward sequences (third-order cycles). No major hiatuses were recognized between these cycles. Therefore, the contacts are interpreted as SB2 sequence boundary types. The Pabdeh Formation, the deeper marine facies equivalent of the Asmari Limestone is interpreted to be deposited in an outer slope-basin environment. The microfacies of the Pabdeh Formation shows similarities to the Asmari Formation. © Springer-Verlag 2005.
Acta Geologica Polonica (00015709)56(3)pp. 229-240
Two successions of Carboniferous sedimentary rocks in Central Iran yielded ammonoid assemblages from one horizon each. In the Ramsheh section, a siltstone with Neoglyphioceras yazdii n. sp. and Dombarites can be assigned to the latest Viséan. The assemblage from the Shesh Angosht Mountain is more diverse with species of the genera Proshumardites, Eumorphoceras, Homoceras, Glaphyrites, Syngastrioceras, and Dombarocanites. This is the first time that the co-occurrence of the genera Eumorphoceras and Homoceras has been recorded. This fauna contains elements of the South Urals and Central Asian occurrences of Bashkirian ammonoids and suggests close palaeobiogeographic relationships.
Rivista Italiana di Paleontologia e Stratigrafia (20394942)113(3)pp. 329-356
Asadabad section in Central Iran is one of the most complete sequences so far described across the Carboniferous of Iran. The stratigraphic and biostratigraphic data on the sediments overlying the Devonian carbonate platform give evidence about the duration of shallow water depositional evolution. There are thirty productive levels with conodonts in the Carbonifeous section ranging in age from early Tournaisian to the top of Bashkirian (Lower expansa - sulcata to sinuosus zones). There is scarce evidence about the elongatus Zone presence - Late Pennsylvanian. Sulcata to anchoralislatus conodont zones in Shishtu Formation and muricatus to sinuosus Zone and a possible elongatus Zone in Sardar Formation have been indentified. These conodont zones are reported for the first time in that area. A crinoidal limestone - key bed horizon, is traceable in the studied area as well as in other parts of Iran. It is Early Pennsylvanian - Bashkirian in age and is correlated to sinuatus-minutus Zone. The studied Shishtu and Sardar Formations (Carboniferous) as well as Vazhnan and Surmaq Formation (Permian) in the section belong to marine near shore sedimentation with many macrofaunal remains.
Journal of Asian Earth Sciences (18785786)29(5-6)pp. 651-665
Cu-Ni-Co-As-U mineralization in the Anarak area of central Iran occurs at the intersection of the Uroumieh-Dokhtar magmatic belt with the Great Kavir-Doruneh fault. In the area, the volcanism associated with the magmatic belt is shoshonitic in character. Chemical analyses indicate that these are subduction related magmas. Detailed investigations in the vicinity of the Talmessi mine indicate that mineralization occurred in two separate stages: a first stage of copper sulphide mineralization with a relatively simple mineralogy and associated with the Eocene magmatism, and a second stage of Cu-Ni-Co-As-U mineralization with a complex mineralogy, which probably formed during another phase of deformation in the Upper Miocene. This later deformation reactivated previously formed faults. The mineralogy, element association and isotopic composition of carbonates for the second phase of mineralization suggest a different origin to that of the first phase. The fluids are likely to be non-magmatic in origin, possibly showing an increased input from meteoric waters. The close spatial association with basic/ultrabasic igneous rocks indicates that these may be the source through alteration and remobilization. The arsenide mineralization in the Anarak area shows many features that are similar to those of the classic five-element deposits. © 2006 Elsevier Ltd. All rights reserved.
Gondwana Research (1342937X)12(3)pp. 324-333
Most of the Infracambrian-Lower Paleozoic sedimentary rocks occurring in Iran cover a crystalline basement. In Central Iran, and the Saghand region along the Chapedony and Poshte Badam faults, the basement complexes show structural vestiges of Precambrian deformational, depositional, erosional, metamorphic and magmatic events. In this region, the basement complexes contain the Chapedony, Poshte Badam, Boneh Shurow and Tashk formations. The prevailing metamorphism, from low grade to high grade, is pre-Pan African Orogeny (i.e. from 2400 to 570 Ma). The presence of greenstone belts, a paleo-suture zone and ophiolitic rocks (i.e. from 2100 to 1500 Ma) around the high-grade metamorphic rocks of the Chapedony Formation, provide evidence that cratonization forming the Iranian basement occurred during the Paleo- and Mesoproterozoic. After formation of the basement complexes, metamorphism of the Precambrian formations and establishment of the Arabo-Iranian coherent platform at the end of Pan African Orogeny, Central Iran broke up during a Neoproterozoic-Early Cambrian extensional tectonic regime. Infracambrian-Phanerozoic sedimentary rocks were then deposited on the basement complexes. The Iranian basement complexes are extensively overprinted by Pan African Orogeny and younger igneous events. © 2006 International Association for Gondwana Research.
Carbonates and Evaporites (08912556)22(1)pp. 1-5
Common features on the sand flat are gypsiferous marl mounds, gypsum interlayers, thin efflorescent salt crust, puffy surface and tufa. The first four features suggest periodic flooding and desiccation. Bi-carbonate-rich springs probably built small tufa mounds. Hard porous surface pitted by small holes with a few centimeters wide and deep is remarkable morphology on the mud flat/saline mud flat. This results from flooding, desiccation and evaporation of capillary brines and rapid and differential rising of the sedimentary surface. Polygonal halite crusts, halite pressure ridges and efflorescent cauliflowers (popcorn) are common features on the salt pan. They suggest volume reduction caused by either thermal contraction or desiccation and pumping of subsurface brine and subsequent evaporation along the cracks between the polygons.
Hydrological Sciences Journal (02626667)52(1)pp. 192-205
Considering the geological conditions of the southwest of Boroujerd and northwest of Doroud, Iran, karst development is analysed with respect to the hydrodynamic behaviour of the main draining springs of the units and the karstic aquifers are classified as either those developed in Cretaceous limestone or those developed in Oligomiocene limestone. For this purpose, the yields of the main karstic springs of the region - Absardeh and Zoorabad (Cretaceous karstic limestone aquifer), Kalamsooz and Azizabad (Oligomiocene karstic limestone aquifer) - were measured and analysed. Analysis of the recession curve is used for hydrodynamical analysis and to construct the conceptual model for estimation of karst development in the selected aquifers. Based on the results, the dynamic storage capacity of the saturated zone in Cretaceous limestone is evaluated as low to medium and that in Oligomiocene limestone as medium to high. The dynamic storage capacity of the unsaturated zone in Cretaceous limestone is evaluated as high and that in Oligomiocene limestone as low to medium. Moreover, the contribution of quickflow in karstic aquifers developed in the Cretaceous limestone drained by the Absardeh and Zoorabad springs is 23.5 and 82.2%, respectively, and that for the Kalamsooz and Azizabad springs (Oligomiocene limestone) is 5.7 and 22.5%, respectively. Flow in the Cretaceous limestone aquifer drained by the Zoorabad Spring is of concentrated type and the main flow occurs in the well-developed karstic conduits. The main flow in the Oligomiocene limestone aquifer, drained by the Kalamsooz Spring, occurs in a network of joints and fractures and the contribution of concentrated flow is very low. The transmissivity of the saturated zone in the karstic aquifer drained by the Zoorabad and Absardeh springs is medium to high and that for the Kalamsooz and Azizabad springs is found to be low. Copyright © 2007 IAHS Press.
Iranian Journal of Science and Technology, Transaction A: Science (10286276)31(1)pp. 7-16
During this research, bacteria resistant to metals were evaluated in the soil of Isfahan Province. According to the sampling locations the soils are classified as agricultural soils, non-agricultural soils and sediments of the Zayanderood Riverbank. The bacteria resistant to lead (2 mM), copper (5 mM), cadmium (0.5 mM) and arsenic (5 mM) were identified, and then during later stages, the minimum inhibitory concentration (MIC) for the growth of the bacteria resistant to metals were determined. The dry cellular weight and the metal uptake rate were also defined for the bacteria resistant to metals.
Historical Biology (08912963)19(2)pp. 173-183
The Asmari Formation is a thick carbonate succession of the Oligo-Miocene in southwest Iran (Zagros Basin). The Zagros Basin was a continental margin attached to the eastern edge of Africa throughout the Phanerozoic. The foraminiferal limestone from the Asmari Formation has been studied to determine its microfacies, paleoenvironments and sedimentary sequences. Based on analysis of larger benthic foraminiferal assemblages and microfacies features three major depositional environments are identified. These include open marine, barrier and lagoon-lower intertidal. These three are represented by eleven microfacies. A carbonate ramp platform is suggested for the depositional environment of the Asmari Formation. The inner ramp facies are characterized by wackestone-packstone, dominated by various taxa of imperforate foraminifera. The middle ramp facies represented by packstone-grainstone to floatstone with a diverse assemblage of larger hyaline foraminifera. The outer ramp is dominated by argillaceous wackestone, characterized by planktonic foraminifera and larger hyaline foraminifera. Two third-order sequences are identified based on deepening and shallowing patterns in microfacies, staking patterns and the distribution of Oligocene-Miocene foraminifers.
Neues Jahrbuch fur Mineralogie, Abhandlungen (00777757)184(2)pp. 117-129
The Cheshmeh-Sefid granitoid complex, hosted by metasedimentry and meta-igneous rocks, north of Golpayegan, Sanandaj-Siran zone of Iran, is a heterogeneous pluton that comprises mainly quartz-monzonite, quartz-syenite, granite and syenite rocks. Geochemically, the granitoids are mostly peralkaline to metaluminous. The2y have similar trace element abundances over a range of SiO2 from 57 to 72.4 wt.%, and have a distinctive A-type chemistry characterized by high contents of Na2O + K2O, Nb, Zr, LREE and low MgO. The P-T conditions of crystallization of the granitoids were determined from amphibole-bearing samples using amphibole-plagioclase thermometry and Al-in-hornblende barometry. Aluminum-in-hornblende geobarometry indicates crystallization pressures of about 5 to 6 kbar; corresponding to intrusion depths of 17 to 20 km. Hornblende-plagioclase geothermometry indicates hornblende crystallization temperatures of 750 to 790 °C. Also, the Zr saturation temperature based on zircon solubility reflects a mean temperature of 776 °C. © by E. Schweizerbart'sche Verlagsbuchhandlung 2007.
Journal of Asian Earth Sciences (18785786)29(5-6)pp. 947-959
The Oligocene-Miocene Asmari Formation of the Zagros Basin is a thick sequence of shallow water carbonate. In the study area, it is subdivided into 14 microfacies that are distinguished on the basis of their depositional textures, petrographic analysis and fauna. Based on the paleoecology and lithology, four distinct depositional settings can be recognized: tidal flat, lagoon, barrier, and open marine. The Asmari Formation represents sedimentation on a carbonate ramp. In the inner ramp, the most abundant lithofacies are medium grained wackestone-packstone with imperforated foraminifera. The middle ramp is represented by packstone-grainstone to floatstone with a diverse assemblage of larger foraminifera with perforate wall, red algae, bryozoa, and echinoids. The outer ramp is dominated by argillaceous wackestone characterized by planktonic foraminifera and large and flat nummulitidae and lepidocyclinidae. Three third-order depositional sequences are recognized from deepening and shallowing trends in the depositional facies, changes in cycle stacking patterns, and sequence boundary features. © 2006 Elsevier Ltd. All rights reserved.
Carbonates and Evaporites (08912556)22(2)pp. 93-100
The Gavkhoni playa lake is surrounded by alluvial fan deposits to the north, south and east and the Varzaneh aeolian sand field to the west. Four major sub-environments including: sand flat/saline sand flat, sand beach, mud flat/saline mud flat and salt pan and seven major facies can be recognized in this playa lake. Sand flat results from transportation of sand by wind from the adjacent sand dunes. The mud flat reflects rapid deposition on a lower flood plain during wet, shortly after sheet floods. The saline mud flat and salt pan is as a result of three stages: flooding, evaporation and desiccation. After flooding, when the shallow ephemeral lake becomes concentrated by evaporation, saline mud flat is formed and finally the formation of salt pan starts. Regarding the sub-environments it is supposed that climatic changes played an important role in sedimentation. During periods of increased run off, sedimentation of alluvial/fluvial occurred and water table was raised at the playa lake. During periods of reduced run-off and falling water table, the saline mud flat and salt pan were formed and wind erosion of alluvial deposits resulted in formation of sand dune and sand flat.
American Journal of Applied Sciences (discontinued) (15469239)4(8)pp. 547-553
The main mineralogical/lithological composition of the Varzaneh aeolian sands is sedimentary and igneous lithics. The minor one is metamorphic lithics and mineral grains (such as quartz, feldspar and heavy mineral grains) respectively. The origin of the sedimentary lithics (mainly carbonates) mostly is from sedimentary rocks exposed in the west and the southwest of the study area. These rocks belong to Cretaceous and Jurassic outcrops. The origin of the igneous lithic grains chiefly belongs to Tertiary highlands, located to the north and the northeast of the study area. The main origin of the metamorphic lithic grains is from the mountain ranges located in the north-western and the western part of the drainage basin of the Zayandeh river. Texture of the aeolian sand grains is similar to the Zayandeh river sediments. Concentration of the aeolian sands at the west of the Zayandeh river delta, variation of their mineralogical/lithological composition from north to south, and textural characterizations of sand grains indicate that the water laid sediments of the Zayandeh river, widespread to the north of the aeolian sands, are the main supply of the aeolian sands and sediments deposited by the two ephemeral streams in the south and the southwest of the sand dunes are minor one. © 2007 Science Publications.
Advances in Water Resources (03091708)31(2)pp. 383-398
An analytical model is presented for the analysis of constant flux tests conducted in a phreatic aquifer having a partially penetrating well with a finite thickness skin. The solution is derived in the Laplace transform domain for the drawdown in the pumping well, skin and formation regions. The time-domain solution in terms of the aquifer drawdown is then obtained from the numerical inversion of the Laplace transform and presented as dimensionless drawdown-time curves. The derived solution is used to investigate the effects of the hydraulic conductivity contrast between the skin and formation, in addition to wellbore storage, skin thickness, delayed yield, partial penetration and distance to the observation well. The results of the developed solution were compared with those from an existing solution for the case of an infinitesimally thin skin. The latter solution can never approximate that for the developed finite skin. Dimensionless drawdown-time curves were compared with the other published results for a confined aquifer. Positive skin effects are reflected in the early time and disappear in the intermediate and late time aquifer responses. But in the case of negative skin this is reversed and the negative skin also tends to disguise the wellbore storage effect. A thick negative skin lowers the overall drawdown in the aquifer and leads to more persistent delayed drainage. Partial penetration increases the drawdown in the case of a positive skin; however its effect is masked by the negative skin. The influence of a negative skin is pronounced over a broad range of radial distances. At distant observation points the influence of a positive skin is too small to be reflected in early and intermediate time pumping test data and consequently the type curve takes its asymptotic form. © 2007 Elsevier Ltd. All rights reserved.
Dams are constructed to control the surface runoff. One of the important points involved in grouting operation and cut off curtain design is the geological and hydrogeological investigation of the site and evaluation of its groutability. The commonly method used for determination of permeability coefficient is water pressure test (WPT). The test includes measurement of water pressure (P) and discharge (Q) pumped in the drilled boreholes and its graphical representation as (P-Q) diagrams which can be interpreted to give rock mass hydromechanical behaviour. Based on the test designation, in Ostur dam site, 400 water pressure tests were conducted and analyzed. Results of these tests are used to determine the type of hydrogeomechanical behaviour. In the other hand, the test grouting was also conducted in continuation of the (WPT) operation and the results have shown that the bedrock of this dam is impermeable, with very low groutability potential. However, the shallow part of rock mass is partly affected due to weathering. The type of flow in these parts is identified as turbulent. From the other side, the rock mass is also intersected in deep parts by hydrothermal veins. The flow type in these parts is different from the shallow parts. © ISRM International Symposium - 5th Asian Rock Mechanics Symposium 2008, ARMS 2008. All rights reserved.
Special Paper of the Geological Society of America (00721077)444pp. 105-122
Arabia-Eurasia convergence is accommodated in the Zagros Mountains of southwestern Iran and in the seismic belts of the central Caspian, Alborz, and Kopeh Dagh of northern Iran. The Zagros is a NW-trending fold-and-thrust belt made up of a 6-15-km-thick sedimentary pile, which overlies the Precambrian meta-morphic basement. During the Zagros orogeny, some of the Precambrian basement and Lower Paleozoic strata were exhumed from depth and are now exposed in the Golpayegan region in the northwestern part of the Zagros Mountains. The tectonic evolution of the Golpayegan region and the exhumation of the old rocks are interpreted as the product of three major sequential geotectonic events. (1) Major thrusts formed during shortening and exposure of the basement rocks in the Aligudarz block. The rock units are strongly imbricated and sheared, which suggest a high amount of cumulative shortening in the northern Zagros. (2) NE-SW-trending extensional faults (e.g., Eastern Mute, Western Mute, and Mahallat faults) formed during lateral extensional movement after middle Miocene time. In this event, a set of NE-SW-trending horsts and grabens was formed. In the horsts (e.g., Hassan-Robat, Mute, and Mahallat horsts), the Precambrian basement rocks and Lower Paleozoic strata are exposed. (3) Strike-slip movements began that remain active today. Strike-slip motions are well documented for the late Pliocene-Quaternary period. In the Golpayegan region, the Shazand and Dehagh faults cut through the NE-trending normal faults and through Quaternary deposits. Drainages are displaced by ∼4 km of dextral movement along the Shazand fault and near the city of Golpayegan. © 2008 The Geological Society of America.
Groundwater and gas inflow toward the tunnel being excavated in Aspar Anticline (at the west of Kermanshah, Iran) cause some problems during construction. Aspar Anticline consists of limestone units from Illam Formation which in Iran is known as a resource formation for Petroleum and natural gas. Detailed investigations (based on result of physical and chemical tests performed on different samples taken from the water and air of the Tunnel) show that about 1 lit H2S gas can be solved in 100 lit water and enter to the Tunnel. It is obvious that solved gas can released in Tunnel by decreasing water pressure and disturbance of water. This study shows that there is a strong relationship between geological and hydrogeological parameters and concentration of gas in the tunnel. These parameters can be considered as indices for identifying potential of gas and water inflow toward the tunnel before excavation. Also, in this paper, the problems related to gassy and water inflow in the tunnel, being constructed with double shield TBM machine are discussed. © ISRM International Symposium - 5th Asian Rock Mechanics Symposium 2008, ARMS 2008. All rights reserved.
