جستجوی مقالات مرتبط با کلیدواژه « دریای عمان » در نشریات گروه « عمران »

Various standards and criteria are existed regarding rubble mound breakwaters. Based on engineering material properties used each of them have own classification . Where as  these types of breakwaters are mainly made by rock material, knowing their  engineering properties such as durability and deterioration and destruction against predominant condition in marine environments is vital in order to preparation of proper classification system. Iranian rubble mound breakwaters in Persian Gulf, Oman Sea and Caspian Sea are mainly designed and made based on regulations, standards and criteria of other countries such as, America, Britain, Japan and Netherland. Using of these standards caused limitations such as the mismatch of the selected stone with the given standards and operating costs are increased. This paper introduces national and international criteria in order to select rock used in break waters. In the following with Concentration, on national criteria, most important indexes of these criteria presented for each type of stone.

In this paper the effect of different coating types of rebar on bars corrosion and durability of self-compacting concrete structures in Oman Sea (Chabahar port) are investigated. Self-compact concrete samples with three types of coating include 40 and 60 micron of zinc, epoxy and uncoated with 3,5 and 7 cm thickness of concrete cover were made and cured according to the related standards in tidal, submerged and atmospheric conditions for 14 months. Compressive strength test according to Standard BS 1881 part 116, water absorption according to Standard BS 1881 part 122, permeability test under water pressure according to Standard DIN 1048, permeability of chloride ion according to Standard ASTM C1152, electric resistance Cabera and corrosion potential according to ASTM G876 and bar weight loss were performed at different ages of samples. The results of weight loss and corrosion experiments indicate better performance of concrete with epoxy and zinc coated bar comparing to uncoated samples at different conditions. Also, 40 micron zinc coating decreased the weight loss of bars about 10 percent comparing with uncoated bars. The epoxy coating was decreased the weight loss about 4-8% on different samples. It should be noted that the increase of concrete cover from 3 to 5 and 7 cm decreased the weight loss from 34 to 27 and 21%.

General attention to carbonate sandshas been begun since the early 1960 in Iran. When the first bore drilled the Persian Gulf’s bed, it drew out layers of this soil type along with sand and shell. However, the large amount of carbonates in this soil was not first diagnosed. The first knowledge of the unique behavior of this type of soil was obtained during pile driving in the construction of an oil platform in Lavan Island, Persian Gulf, in 1968. In this operation, after a number of 30 inch pipe sank into the cemented soil for about 25 feet, they suddenly had a free fall with no resistance up to depth of 50 feet. Carbonate materials and aggregates can be found in nature in different shapes. The majority of them are made of calcium carbonate or other types of carbonate with soft and loose grains that can break easily. These soils are of remarkable importance in offshore engineering.Since early 70s, a great amount of studies have globally been conducted for identifying the unique engineering characteristics of carbonate sands. Different behavioral parameters including strain-stress behavior, shear strength, internal friction angle, volumetric behavior, elastic and shear modulus, Poisson’s ratio, carbonate content, shape of carbonate grains andetc have been studied. No certain laboratory methods or field study plan have yet been provided to obtain appropriate parameters for designing foundations in carbonate soils. Despite this, performing a number of laboratory and field experiments can be helpful. Executing at least amount of experiments to determine the following matters are essential:• Material composition, especially calcium carbonate content• The origin of the materials to distinguish between skeletal and non-skeletal deposits• The properties of the gains such as angularity, porosity, and initial void ratio• Compressibility of materials (using consolidation test)• Strength parameters of the materials, especially internal friction angle• Cementation, at least quantitativelyIn this paper, shear behavior of four skeletal carbonate sand samples obtained from the northern coasts of Persian Gulf and Oman Sea are investigated. Regarding some parameters of samples such as particle size distribution, physical properties, microscopic images of grains, compressibility, drained triaxial shear behavior, elastic modulus and internal friction angle it was attempted to promote geotechnical knowledge and improve civil engineers understandings of carbonate soils in this part of the world. On the basis of experimental tests like one-dimensional consolidation and triaxial tests, it was determined that despite a number of similarities between the shear behavior of carbonate sands, behaviorally they depend on the grains shape and size, initial particle size distribution and void ratio, calcium carbonate content, confining stresses and applied strains. Although all specimens were selected from the southern coasts of Iran, but a large number of difference was observed between them in terms of shear behavior and strength

In traditional hydrographic surveys, chart datum is usually determined using spectral analysis of coastal tide gauge observations based on the lowest water level. Due to the variation of tidal amplitude and phase components in different locations, such chart datum is only valid in coastal areas around the tide gauge stations; it is then hardly accurate when a few tens of kilometers away from the tide gauge stations in the off-shore areas. This study models the separations between the elliptical reference WGS84 and the chart datum using the data collected by the satellites Topex/Poseidon and Jason-1 for the periods of 1992-2002 and 2002-2008 in Persian Gulf and the coastal tide gauge data of the Oman Sea. The major advantages of the technique used in this study are highlighted as follows. The satellite altimetry observations on the shores and also in the shallow water is not of good accuracy and precision. An appropriate solution to this problem is to use coastal tide gauge observations near the time series generated from the satellite observations. On the other hand, chart datum determination based on the coastal tide gauge observations is suitable only for the areas close to the coastal tide gauge stations. However, due to the amplitude and phase variations of the tidal components in different parts of the sea, the accuracy of such a chart datum is not appropriate for the areas that are far away from the tide gauge stations. In this study, the satellite altimetry observations are combined with the data obtained from the coastal tide gauge stations. Due to the existence of point-wise time series in the study area and also creation of the “quasi tide gauge” points using the satellite altimetry observations, both of the problems mentioned above (i.e. weakness of the satellite altimetry observations and the chart datum determination based on the use of the coastal tide gauge observations only) can be solved. This will then lead to higher accuracy of the chart datum determination in the entire area. To achieve higher accuracy, observations of the tide gauge stations are also used. It is because the distances between the tide gauge stations and the time series obtained from the satellite observations are considerably large (sometimes more than 20 km). Therefore, this combination will lead to the establishment of a regular and continuous network of tide gauge observations in the entire area having acceptable accuracy. To determine this model, sea level variations due to the tide, polar motion variations, plates tectonic movements and all the factors affecting the potential tide with significant components (M2, S2, K1, O1) and even less important components such as signals with the period of 14 days, monthly, semi-annual, annual, 8.5 year and 18.6 year are considered in the case study area. It is also highlighted that because the satellite altimetry observations are only available on periods of 9.915 days, the high-frequency tidal signals cannot be detected using these data. Therefore, these frequencies are also included into the functional part of the model. Based on the above strategy, the separation between the elliptical reference and the chart datum has been computed by comparing the tide gauge data and the satellite altimetry data for the period of 2002-2005.