بررسی عددی پدیده قوس زدگی در هسته سد خاکی غیرهمگن بافت واقع در استان کرمان

Today, large dams, including the type of soil or concrete offshore structures are the most important that in water supply needs of human societies play a major role. Dam stability in recent decades has been of particular interest to designers of earth dams. Soil arching in zoned embankment dams is a phenomenon where stresses are transferred from the softer core soils to the stiffer shell soils due to differential movements between the core and shell materials. In these structures, excessive stress transfer due to soil arching will lead to hydraulic fracturing occurrence in the low permeability core soils; which can cause significant internal seepage and erosion problems. This process is usually accompanied by internal erosion of soil particles, which leads to the formation of soil pipes or other erosion features that eventually cause failure of the dam. statistically shown that progressive piping and erosion are the primary contributing factor in 30% to 50% of earth dam failures. The easiest way to prevent hydraulic fracturing from occurring is to ensure that the total stresses along the upstream side of the clay core are always greater than the seepage-induced pore pressures. Thus, some authorities argue that making use of highly soft materials in core of dam which have not enough shear stress to suspend on shell materials is useful. Installation of instrumentation and monitoring during construction and initial operation will help to assess important parameters. Statistics show that the highest number of failures unstable dams, Respectively is related to earth dams, gravity, pebbles, multi-arc and arc. In this research, by modeling the Baft earth dam in finite element software PLAXIS and compare the results with the instrument results, confirmed the authenticity modeling and then, the arching phenomenon has been studied in the earth dam desired. Investigated parameters include the width of the core (core slide slope), the upstream filter layer thickness and compressibility foundation. The effect of the core side slope angle on soil arching between the clay core and the upstream shell was investigated by simulating three different core side slopes for a vertically oriented clay core: 1V:0.25H, 1V:0.33H and 1V:0.50H. To further investigate the impact of transition layer thickness, three different models with upstream filter thicknesses of 1, 3 and 6 m were analyzed. The effect of foundation compressibility on soil arching between the clay core and the upstream shell was investigated by simulating foundation rock having three different levels of compressibility. The elastic rock modulus values used in the current study were: 4×105, 8×105 and 12×105 kN/m2. that the effective parameters between these parameters to reduce of arching, is core slide slope that The core slide flatter ratio arching dramatically reduced. Then the thickness of the layer filter, which increases its thickness is reduced ratio arching. Thicker filter layers also have the additional advantage that, if they are designed properly, they can help prevent erosion of core materials into the downstream soils if a crack in the core does occur. The effect modulus of elasticity of the foundation had little influence and is negligible.