جستجوی مقالات مرتبط با کلیدواژه « زهکشی » در نشریات گروه « عمران »

The surface texture depth is an important indicator for evaluating the skid resistance capabilities and providing suitable surface drainage conditions for asphalt pavement, which has a direct effect on the safety and comfort of road users. Texture evaluation is one of the main goals of the pavement management system. Three-dimensional evaluation is the most accurate method of measuring pavement texture characteristics. In this paper, a three-dimensional automatic device based on a hybrid imaging technique is presented. In this device, a system consisting of two-dimensional digital cameras is designed to provide the required image data. The proposed system has a tool for reducing surface friction. This system also makes it possible to evaluate the texture in rainy conditions. Based on the two-dimensional images taken from the pavement surface, the three-dimensional models of the pavement texture are presented. A method for calculating the mean texture depth is presented. Measuring the depth of pavement texture in different directions is a the capability of this method, which makes it possible to uniformly evaluate the depth of the texture in different directions and find the critical direction for texture drainage capacity. The proposed system has been used to measure the depth of texture in different sections of pavement and the results in have been compared with the results of the standard sand patch method. This comparison shows a high correlation between the results of the proposed method and the standard pavement texture evaluation method.

Collapsible soils are one of the problematic soils, as they exhibit good stability in dry conditions but undergo sudden and significant settle-ments upon water entry. The surrounding layers of collapsible soil can be either permeable or impermeable, but the existing devices for determining the collapse potential lack the ability to model the drain-age conditions around the collapsible soil layer. In this study, an ap-paratus capable of modeling drainage conditions was constructed. A collapsible soil was made in laboratory, and its collapse potential was determined using single and double oedometer tests as well as the constructed apparatus. The results show that drainage conditions are an influential factor on the behavior of collapsible soils. The col-lapse potential obtained from this apparatus is lower than the col-lapse potential obtained from the oedometer test. The comparison of the two conditions with drainage and without drainage in two point and wide water distributions shows that in both water distributions, the collapse potential is higher in the condition with drainage than in the condition without drainage. For example, in the point distribution, the collapse potential with drainage is 27.7% higher than the without drainage, while in the wide distribution, it is 19.5%higher.

Increased population and urbanization, on the one hand, and global warming and climate change, on the other hand, have resulted in urban hydrological problems. Seasonal floods, as well as a lack of urban water supplies in specific seasons, inflict significant harm to numerous countries every year. Following the happening of frequent floods and resource scarcity, Chinese researchers introduced a new concept of sponge cities in 2014 to progress toward sustainable development. The development of the sponge cities program will be the responsibility of government agencies due to the broad-scale coverage of the areas and the necessity for substantial coordination and licensing across the country. Pervious concrete is considered as a new technology in the development of urban spaces in order to control urban runoff in recent years in many developed countries as sponge cities. In the past, this technology was associated with technical challenges such as limited mechanical resistance, durability, clogging which were solved with the development of technology. This technology, along with other components of sponge cities introduces a new concept of sustainable development. In this study, the components of Sponge City are introduced and by reviewing previous studies, the challenges of realizing this concept are studied.

One of the most important infrastructures of the country is the production of quality materials for construction operations. Improper use of materials in the process of asphalt construction, causes rapid destruction, shortening the pavement life and causing a lot of damage. This phenomenon causes a lot of costs to bring the pavement to acceptable quality. Given that gradation accounts for a large part of the volume of asphalt pavements, it is obvious that this part has a significant impact on the behavior and performance of pavement. Improper gradation use for asphalt pavements causes numerous failures including rutting and fatigue cracks. The route of Azadshahr-Mino Dasht is one of the busiest roads in the country, which has suffered from rutting breakdowns and numerous fatigue cracks. The present study investigates the causes of these failures and finally offers solutions to eliminate these failures.

The effects of earthquakes on the road beds and the structures on it (the site in general) can be very variable, so that in some areas the acceleration of the earthquake at the ground level is amplified or, conversely. This issue can be related to several factors. In the present study, the Earth's response has been investigated by looking at the characteristics of the Kermanshah regional bed due to the application of force caused by the Upland earthquake with the help of two-dimensional finite element software (PLAXIS) .Two-dimensional numerical analyzes were performed for dry soil, drained saturated soil and undrained saturated soil. Results show that the presence of pore water (in undrained conditions) can increase the acceleration on the earth's surface up to 3 times compared to the dry state mode. However, at the same time, the overall displacement rates in all three modes of dry bed, drained saturated, and undrained saturated condition are not much different. Another noteworthy point about Kermanshah's site is that the closer to the soil surface (the location of the structure), the ground response more and more grows, and finally reaches its maximum in surface level.

Tunnelling in a saturated soil often produces a long-term interaction between the tunnel lining and the surrounding soil. In ltration and external pore-water pressures are often important factors that must be considered in the lining design. Development of pore water pressure may accelerate leakage and cause deterioration of the lining. This can be particularly troublesome to structural and functional components of the tunnel and can often lead to structural failure. In this paper, an axi-symmetric circular tunnel under the groundwater table is modeled using nite dierence software, and dierent conditions, such as an impermeable tunnel, a permeable tunnel and a lining drainage system with varying permeability are investigated. The structural behaviour of the lining and ow through the tunnel lining were modelled using a combination of beam and solid elements. The eects of tunnel parameters, such as depth and diameter and variation of underground water levels, on the eectiveness of the lining drainage system are examined. Moreover, the deterioration of a drainage system caused by clogging is investigated and the importance of giving careful consideration to lining permeability and hydraulic boundary conditions is highlighted. As a result of coupled analysis, a lining drainage system in a shallow tunnel with small diameter is more ecient, and eective drainage conditions reduce pore water pressure loads, which decreases the bending moments and tensile stresses of the tunnel lining. By performing a parametric study for a tunnel with dierent lining permeabilities, a design curve to evaluate pore water pressure loads on the lining has been proposed. It is shown that the hydraulic deterioration of the drainage system signi cantly develops a magnitude of pore water pressure load on the tunnel lining.