جستجوی مقالات مرتبط با کلیدواژه « شیروانی های خاکی » در نشریات گروه « عمران »

In recent years, the number of waste tires around the world is increasing rapidly and has become an environmental and economic problem. Today, accumulation of waste tires in the environment is one of the biggest problems to the environment and recycling waste tires is the best strategy to solve this problem. The use of waste tires in construction and geotechnical projects is one of the effective strategies in this regard. In this paper, experimental tests of earth slope reinforced with waste tires based on horizontal displacement (25 experiments) has been performed. During incremental loading, digital images were taken from the models and the particle image velocity (PIV) method was used. Parameters such as tire layer length, number of layers and tire layer position are considered as variable. The results show that the use of tire reinforcement has a significant effect on reducing horizontal displacement under the foundation and slope surface. Horizontal tire rows are the best reinforcement location in terms of improved bearing capacity and lateral displacement. When four layers of 60 cm long reinforcement tire are placed in the upper half of the slope, the bearing capacity increases 3 times and the lateral displacement under the foundation decreases by 3.1 times. When three layers of tires with a length of 60 cm are placed in the upper third of the slope, the bearing capacity increases by 2.3 times and the lateral displacement under the foundation increases by 1.3 times. When six, eight, and nine layers of reinforcing tires with a length of 60 cm are placed into the slope, lateral displacement under the foundation is reduced more than 3.5 times. In Iran, eight largest tire factories produce 13.5 million tires in a year. It also imports 4 million tires a year. Therefore, 17.5 million tires are the annual consumption of the country. More than 100,000 tires are the product of factory production line waste, as well as used tires. Waste tires have been used to strength retaining walls, foundations, improve soil properties, embankments and etc. Therefore it is believed that soil reinforced with waste tires become a wider application in the future, especially in countries with low worker costs. In this paper, the test was performed in a box with length, width and height of 2, 1, 1 m, respectively. The test material used in this study is sand in the dry state. The maximum and minimum dry sand densities are 19.43 and 16.36 kN/m, respectively. Internal friction angle and cohesion were measured by direct shear test at 38 degree and about 0 kPa, respectively. Digital images taken from the front of the test box during the experiment. Images were processed using GeoPIV software developed at the University of Cambridge. The results of this study are as follows:1. The best position in terms of bearing capacity and lateral displacement is to use four layers of reinforcing tire in the upper half of the slope.2. As the length of the reinforcement layer increases, the bearing capacity increases significantly and the lateral displacement decreases. Especially when the length of the reinforcement tire is 60 cm and the length of the reinforcement passes through the rupture wedge, the improvement in bearing capacity and lateral displacement of the foundation is noticeable.3. The best position in the three layers of reinforcement tire on the slope in terms of bearing capacity and lateral displacement is one-third of the upper slope.4. The presence of a tire in the lower third of the slope has little effect on improving the bearing capacity, lateral displacement of the foundation and the slope surface compared to the slope without reinforcement.

The number of waste tires around the world has been increasing rapidly in recent years and has become an urgent a serious environmental and economic problem. Today, accumulation of waste tires in the environment one of the biggest threats is to protect the environment and recycling of scrap tires is the best strategy to solve the problem. One of the methods of disposal of waste tire is to use in construction and geotechnical projects. Therefore, it is believed that the reinforced soil with tire becomes a wider application in the future, especially in countries where labor costs are low and machinery is not widespread. Eight large tire factories in the country produces an average of approximately 13.5 million tires ring. With an import of more than 4 million tire rings, an average of 17.5 million tire rings are an average annual consumption of tire. Among which on average, more than 100 thousand ring waste the production line of various factories, with tires consumed and used, and significant high volume of waste creates. In this paper, an experimental study of the soil slopes reinforced with scrap tire horizontal layer based on displacement investigated. Digital images were taken of the side of the model during incremental loading and particle image velocimetry method (PIV) was used. Some important parameters such as the length, number and location of the reinforcing tire layers are studied in this paper. Also in this paper compares the unreinforcement slope with soil slope reinforcement different arrangements and numbers of different layers with variable length (total 25 experiments) have been studied on the horizontal displacement of the slope. The results show that use of tire reinforcement has significant effects on the horizontal displacement under the footing and edge slope. The best reinforcement position is to improve the bearing capacity and lateral displacement of the upper slope. When the four-layer reinforced tire with a length of 60 cm placed in the upper half of the slope is compared to unreinforcement slope, the bearing capacity more than tripled and lateral displacement on the footing of more than 3.10 times and lateral displacement of the upper edge of the slope of more than 2.7-fold reduction. When the six, eight and nine layers of tire reinforcement with a length of 60 cm on the slope are compared to unreinforcement slope the lateral displacement under footing the substrate more than 3.5 times and the lateral displacement in the upper edge of the slope is more than 2 times lower. Three layers of tire with a length of 60 cm in the upper one-third of the slope relative to the unreinforcement slope, the bearing capacity is more than 2.3 times and the lateral displacement of the beneath footing and the edge of the slope are 1.3-1.6 times, respectively. As the length of the reinforcement layer increases, the bearing capacity and lateral displacement is reduced significantly increase. Especially when the length of the reinforcement tire is 60 centimeters, reinforcement length of the rupture wedge passes improve the bearing capacity and lateral displacement footing is significant.

This paper deals with three-dimensional evaluation of the slopes on the basis of limit analysis. An upper-bound technique of limit analysis is used in this paper to determine either the bearing capacity of a shallow foundation near a slope or the safety factor of the slope. The theorems of limit analysis (upper and lower bound) provide a powerful tool for solving problems in which limit loads need to be found. According to the upper-bound theorem, for a kinematically admissible velocity field an upper bound of the collapse load can be obtained by equating the power dissipated internally in an increment of displacement to the power expended by the external loads. Such kinematically admissible velocity fields have to comply with the kinematical boundary conditions and compatibility conditions. A rotational mechanism consisting of three slip surfaces is used to determine the factor of safety for a slope or the ultimate limit load of a foundation with eccentric load near a slope. This mechanism includes two lateral surfaces and a surface at bottom. As the soil is assumed to obey the associated flow rule, the angle between the relative velocity vector and velocity discontinuity has to be equal everywhere with soil's friction angle (?). The geometries of lateral surfaces are represented by a nonlinear differential equation. A surface with log-spiral section is used for bottom surface of the mechanism. To obtain the minimum upper-bound, an algorithm is proposed to optimize the failure mechanism. Results from this algorithm for typical conditions are comparable to those of other existing methods. Dimensionless diagrams for various conditions are presented which can be used to predict the bearing capacity of a foundation with eccentric load located on a slope.