جستجوی مقالات مرتبط با کلیدواژه « earth slope » در نشریات گروه « عمران »

One of the proposed solutions to strengthen and improve the stability of earth slopes is to use piles that will be placed vertically and along the slope in a row. In this research, the parameters affecting the stabilization of soil slopes were investigated using the finite element numerical model with ABAQUS software. The results showed that the location LX/L equal to 0.6 is the most optimal place where the pile can be placed since the largest displacements have taken place there. According to the studied numerical models as well as the soil conditions, it can be said that the failure surface does not pass between the two soils and the failure surface remains only in the upper soil area. As the factor of safety increases in models where the pile location changes, the values of vertical and lateral displacement of the soil increase. In other words, with an increasing factor of safety, the amount of lateral and vertical displacement of the pile also increases.

The complexity of the conditions and behavior of soil materials, the existence of various hypotheses in the formulation of stability analysis, and the mechanism of slip and failure of slopes are among the main factors influencing the methods of soil slope stabilization. The cracks are a common occurrence on earth slopes that require a method that includes the presence of cracks in the stability assessment based on the kinematic approach of finite element and finite-difference. While many cracks may be present on a slope, the failure mechanism typically involves a crack whose position has the greatest negative effect on stability. In the present study, the geometry of critical failure surfaces, including the most undesirable cracks for slopes with different transverse and slope constraints, has been analyzed. Based on the findings of numerical modeling, it can be concluded that the critical height of the slope decreases due to the presence of cracks. This decrease, however, decreases with the angle of slope inclination. The results showed that according to the finite difference method, the most critical crack position for homogeneous soil slopes will be at the slope toe because, in this range, crack formation creates the lowest factor of safety.

The Iranian plateau is one of the seismic active zones of shallow crustal earthquakes in the world so that annually thousands earthquake occurs in the Iranian plateau. Meanwhile, due to the effect of topographic and geological characteristics of its relief, the Iranian plateau is subjected to diffuse phenomena of landslide, especially in Alborz and Zagros mountains, which are exacerbated by the high seismic activity. The earthquake-induced landslides have reportedly caused major human fatalities and economic losses in Iran. The prediction of sliding displacement can decrease landslide hazards to the civil engineering strcutures. The semi-empirical models have recently received more attention from the geotechnical earthquake engineering practitioners because of their applicability, simplicity, and reasonable performance in large displacements. The rigid block-rotation approach was developed based on the increase of critical acceleration caused by the downward movement of sliding soil mass. This paper represents a semi-empirical model for the earthquake-induced displacement of Iran's slopes using the rigid block-rotation approach. A collection of 3954 strong motion records was used to generate the model based on the results of slidinganalyses. The semi-empirical model is presented based on more than 138,000 rigid block-rotation analyses using several input parameters. The model predicts sliding displacement in terms of yield coefficient (ky), slip length of sliding mass (L), and Arias Intensity (Ia). It is shown that slip length of sliding mass has an important role in the prediction of seismic permanent displacement, which is generally ignored in the semi-empirical models. The proposed model can be simply used to estimate the seismic displacement of slopes and earthquake-landslide hazards in seismic prone regions of the Iranian plateau.

The present paper, illustrated the results of numerical investigation and a series of experimental modeling on optimization of pile length in reinforcing earth slopes using piles. In this paper, the length of different piles with various diameters analyzed and the relationship for optimal length proposed. Stabilization of earth slopes and proposing different methods is one of the main issues in geotechnical engineering. Using numerical and analytical methods in stabilization of earth slopes reinforced by piles are common method, which, carried out by lots of researchers. Finding the optimal length of piles in reinforced slopes is an important matter that reduces the expenses and make the project economical.

To find the critical slip surface is one of the most important steps in this analysis. The shape of slip surface in many analyses is circular which convenience for calculating is. Optimization methods are one of the methods to find critical slip surface. In this paper is presented a new method to find critical slip surface and minimum factor of safety using DOSS program. DOSS program is written by authors in FORTRAN and can find critical circular slip surface by using grid search and critical line segments slip surface by using optimization method. This program is applicable for homogeneous and non-homogeneous materials with water level. The examples prove the efficiency and precision of the suggested method.

The increasing demand for engineered cut and fill slopes on construction goals has increased the need of understanding of analytical methods, investigation tools and the most important stabilization methods to solve slope stability problems. The first step to maintain the stability of an earth slope is performing excavation in the slope crest or/and filling in the slope toe. This is the cheapest way (model) for stabilization of earth slopes. If the model cannot provide the required factor of safety, it is necessary to use other stabilization methods. Numerical and laboratory methods are useful for modeling earth slopes stabilization. Modeling the stability of earth slopes using numerical methods is a common practice in geotechnical engineering. Moreover , stabilization of earth slopes using piles has been practiced by many researchers by using numerical and analytical methods. Application of numerical and analytical methods to stabilization of earth slopes using piles is an issue commonly discussed by various researchers. Although , numerical and analytical methods have special capabilities, laboratory modeling is more reliable. Stability slope analysis has attract lots of researchers attention all across the world and it shows the significance of this matter. When we are suspicious about stability of earth slopes, immediate actions and preventative steps should be used for suppression of instability occurrence. Many projects intersect in valleys and rides , which can be prone to slope stability problems. Natural slopes that have been stable for many years may suddenly fail because of many reasons, therefore finding useful techniques for these matters now days are a great concern for geotechnical engineers. In all earth slopes the primary way for stabilization is the excavation in slope crest and/or filling slope toes , if this action would not increase safety factor enough , other procedures should be applied. Three common styles of stabilization methods are ; vertical reinforcement (such as stone columns and piles) , horizontal reinforcement (like Geo - grids) , oblique reinforcement (such as nailing). Stability of natural slopes is one of important issues in Geotechnical engineering. using easy and economical methods for improving stability of slopes are one of the greatest challenges that face engineers. One of the common methods that is use for increasing the safety factor of slopes is stone columns. All of the experimental tests were modeled and compared using the limit equilibrium (LE) and finite element (FE) methods, which are compliant with each other. Understanding of soil property is crucial for analysis of earth slopes, in this study effect of cohesion in embankment is considered, and based on exact understanding of this property and performing laboratory modeling and by using finite element method software (PLAXIS2D) and finite difference method software (FLAC3D), results are achieved. The sand slope is saturated through precipitation and failure after loading by installing the stone column at the middle of slope. Experimental studies in this article have the potential to give valuable information about effects of embankment cohesion and penetration depth of stone column into the stiffer layer, in stability of stone column reinforced earth slopes.

What should be considered at the beginning of any stabilization process besides slope safety is the minimization of expenses. Therefore, excavation on slope upstream and/or filling slope downstream and/or moderating slope angle are the primary and effective stabilization methods. If these methods cannot provide the desirable factor of safety it would be necessary to put effort in other methods such as increasing soil strength parameters, draining surface water and sub-surface (ground) water at embankments, and installing retaining walls and piles. Implementation of these solutions is usually costly and sometimes in order to achieve a desirable factor of safety it is necessary to combine one or several methods. Anyway, the aforementioned solutions are aimed at mitigating the driving force behind ruptures and/or increasing resistive forces.
Slopes stabilization methods can be studied as empirical, analytical, and numerical methods. This classification has been so far used by researchers and has undergone numerous studies. One of the methods used for improving resistive forces is the installation of piles in earth slopes. Installing piles for stabilizing susceptible earth slope is an effective way of preventing the imbalance of force and instability.
Stabilizing effect by using pile is provided by the passive resistance of the pile below the slip surface and load transfer from the sliding mass to the underlying stationary soil or rock formation through the piles due to soil arching mechanism.
Moreover, slope stability and optimizing pile location by installing a row of piles have been studied by many researchers.
The piles are embedded in the stable soil by the length 5D (D=pile diameter), because the zone of influence of each pile has been demonstrated not to exceed 5D and the length of the pile is restricted to 10D.
In this paper a new method is presented for estimating of displacement and lateral force acting on stabilizing piles in earth slopes. The growth mechanism of lateral force acting on stabilizing piles in a row due to the surrounding ground undergoing plastic deformation is discussed, and its theoretical analysis is carried out considering the interval between the piles (Ito and Matsui, 1975).
Several methods have been proposed to determine the force exerted on the pile in addition to having the merits, defects such as lack of accuracy required in a particular interval between the piles. In this paper with regarded to initial slip surface and acting force due to weight of failed soil is proposed lateral force acting on piles.
1. The assumptions are considered in this paper are,
2. The suitable location for installing of piles is middle of slope.
3. The pile behavior is considered as elastic.
4. The soil behavior is considered as elastoplastic.
5. The pile tip is embedded in the stable soil by the length 5D.

Stability analysis of earth slopes is among the major issues raised in geotechnical engineering which has involved so many researchers in different parts of the world. When stability of an earth slope is suspected، it is necessary to take preventive measures before instability happens. The first step to maintain the stability of an earth slope is performing excavation in the slope crest or/and filling in the slope toe. This is the cheapest way (model) for stabilization of earth slopes. If the model cannot provide the required factor of safety، it is necessary to use other stabilization methods. Numerical and laboratory methods are useful for modeling earth slopes stabilization. Modeling the stability of earth slopes using numerical methods is a common practice in geotechnical engineering. Moreover، stabilization of earth slopes using piles has been practiced by many researchers by using numerical and analytical methods. Although numerical and analytical methods have special capabilities، laboratory modeling is more reliable. Hence، it is discussed in this article. Stabilization of earth slopes with reinforced concrete piles is one of the important concerns of geotechnical engineering. Application of numerical and analytical methods to stabilization of earth slopes using piles is an issue commonly discussed by various researchers. Optimal location of concrete pile for stabilization of earth slope by means of numerical and analytical methods، has been practiced by various researchers. Their efforts have led to various results raising the question of what the optimal place for installation of a pile is. It seems that no experimental studies are conducted in this regard، which is discussed in this article. Experimental studies conducted in this article have the potential to solve the problem caused by varying and sometimes contradictory results of numerical analyses performed to find the optimal pile location. In this article، an experimental analysis of a homogeneous sand earth slope is conducted. The slope is saturated through precipitation and failure after loading by installing the reinforced concrete pile in different locations. All of the experimental tests were modeled and compared using the limit equilibrium (LE) and finite element (FE) methods، which are compliant with each other. The results obtained by experimental tests show the optimal location for installing reinforced concrete pile in a homogeneous sand slope for achieving the highest factor of safety and reduce costs of stabilization. In the present article، the optimal pile location for slope stabilization is determined by conducting laboratory studies of a layer sand slope saturated through precipitation. The resultant failure mechanism leads to acceptable results that help choose the optimal location for pile installation. The slope is stabilized by repeating the test and installing the pile in the optimal location، which is the best place to install the pile. The FE method (Plaxis software) and LE method were used to confirm the laboratory tests as well.