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The pressuremeter test has proved to be a useful tool for geotechnical engineers to determine the in situ properties of soils. However, results indicate that the strength values derived from pressuremeter tests are often quite different from those obtained from good laboratory tests and other in situ tests. It is believed that a major part of this disagreement may be due to the influence of pressuremeter geometry. This is because, in most analyses, the pressuremeter is assumed to be infinitely long, although commercial pressuremeters are of finite length. Therefore, it is necessary to investigate the possible effect of the finite pressuremeter length on soil parameters derived from the tests. A two-dimensional axisymmetric finite-element analysis was used to simulate pressuremeter tests. It was found that the finite pressuremeter length has a significant effect on derived soil properties. Experimental studies on the effect of a finite pressuremeter length reported in the literature are not sufficiently comprehensive to reach a definite conclusion about the effect of pressuremeter geometry on derived soil properties. In the present study, therefore, a large number of pressuremeter tests with four different length/ diameter ratios (L/D = 5, 10, 15, 20) were conducted in a 1 m × 1 m calibration chamber located at the university of Newcastle, Australia. Based on the results of those laboratory pressuremeter tests, experimental correlations are presented which can be readily used in practice to account for the effect of pressuremeter geometry on the derived soil properties.
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.
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.
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.
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.
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.
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.
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.
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.
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.
