The influence of soil type on internal erosion

Soil erosion is a natural process. It becomes a problem when human activity causes it to occur much faster than under natural conditions. Soil erosion by water, wind and tillage affects both agriculture and the natural environment. Soil loss, and its associated impacts, is one of the most important of today's environmental problems. Soil erosion is a naturally occurring process that affects all landforms. In agriculture, soil erosion refers to the wearing away of a field's topsoil by the natural physical forces of water and wind or through forces associated with farming activities such as tillage. This problem can be a slow process that continues relatively unnoticed or can occur at an alarming rate, causing serious loss of topsoil. Soil compaction, low organic matter, loss of soil structure, poor internal drainage, and soil acidity problems are other serious soil degradation conditions that can accelerate the soil erosion process. Soil quality, structure, stability and texture can be affected by the loss of soil. The breakdown of aggregates and the removal of smaller particles or entire layers of soil or organic matter can weaken the structure and even change the texture. Textural changes can in turn affect the water-holding capacity of the soil, making it more susceptible to extreme conditions. Many dam ruptures events have occurred throughout the world, some of them were reported by Foster and al. [1]. Then main cause was piping phenomenon that occurred in the foundation soil or in the dam structure. Serviceability of hydraulic infrastructures needs considering vulnerability of soil to internal erosion under the action of a seepage flow, [2,3]. Understanding the underlying mechanisms and quantifying the effects of pertinent variables that affect this phenomenon is of great importance in order to prevent such catastrophes. In this work, the water erosion is modeled in the fluid/soil interface during the hole erosion test (HET). The Hole Erosion Test is commonly used to quantify the rate of piping erosion. The aim of this work is to predict the erosion of soil in the fluid/soil interface by using the Fluent package .This modeling makes it possible describing the effect of the flow on erosion in the interface fluid/soil by using the turbulence model equations, and predicts a non uniform erosion along the hole length unlike the usual one dimensional models or two dimensional models. In particular, the flow velocity is found to increase noticeably the erosion rate. Effects on the wall-shear stress resulting from varying flow velocity and applied hydraulic gradient are analyzed. Various parametric studies were performed and had shown that the three-dimensional modeling introduced in the present study showed that the erosion rate is not uniform along the pipe wall as observed experimentally after performing the standard hole erosion test. The aim of this study is to describe the biphasic turbulent flow at the origin of erosion taking place inside the porous soil sample by considering the influence of variation of the concentration of clay contained in the flowing fluid. A Computational Fluid Dynamics (CFD) approach is used to investigate the shear stress that develops at the water/soil interface and which represents the main mechanical action that causes surface erosion

Rupture des ouvrages hydrauliques par Renard hydraulique

L'érosion interne/externe d'un sol est un phénomène complexe représentant une source très importante de problèmes lorsqu'on considère la sécurité des digues et des barrages. Ce phénomène qui se traduit par l'apparition de fuites très graves sous les ouvrages hydrauliques, le renard hydraulique, est l'une des causes majeures de leur rupture. La survenance de tels accidents peut engendrer des pertes matérielles et en vies humaines désastreuses. Elle est liée à la formation et au développement d'un tunnel continu entre l'amont et l'aval de l'ouvrage, le conduit de fuite s'agrandit par érosion (renard) jusqu'à provoquer l'effondrement de la structure. L'érosion interne de sol est modélisée en utilisant le logiciel Fluent. L'écoulement fluide dans un barrage en terre est supposé être gouverné par les équations de Navier-Stokes et le corps du barrage est supposé obéir au système des équations de Biot qui couple l'équation de Darcy avec les déformations poroélastiques axisymétriques. Une équation explicite qui exprime la loi d'érosion est écrite sur l'interface qui sépare l'eau et la paroi du barrage

Reinforcement of concrete using Glass Fiber Reinforced Polymer

The use of composite materials such as fiber reinforced polymers in strengthening and repairing of structural elements, particularly those made of reinforced concrete, is widely spreading. Among the fiber reinforced polymers (FRP) used for concrete strengthening, GFRP because they are more ductile and cheaper than carbon fibers and can be considered as an alternative solution to repair and strengthen concrete elements. The GFRP enhance significantly the ductility and strength of concrete by forming perfect adhesive bond between the wrapping material and concrete. Present study mainly emphasizes on effectiveness of external GFRP strengthening for concrete beams and columns. Total five circular concrete columns of 320 mm in height and 160 mm in diameter, and 30 concrete rectangular beams with a section of 40 mmx40 mm and 160 mm in length. Two columns were control and the rest three columns were strengthened with three types of GFRP. For beams, fifteen of them was control and the others were strengthened by GFRP with U-shape. All the test specimens were loaded to fail in axial compression and strain for columns, and under three-point bending for beams. The test results clearly demonstrated that compared with the ordinary concrete, the axial load carrying capacity and flexural strength increase for the reinforced concrete no matter the kind of the GFRP used even if it was in different storage condition

Reinforcement of concrete using Glass Fiber Reinforced Polymer

The use of composite materials such as fiber reinforced polymers in strengthening and repairing of structural elements, particularly those made of reinforced concrete, is widely spreading. Among the fiber reinforced polymers (FRP) used for concrete strengthening, GFRP because they are more ductile and cheaper than carbon fibers and can be considered as an alternative solution to repair and strengthen concrete elements. The GFRP enhance significantly the ductility and strength of concrete by forming perfect adhesive bond between the wrapping material and concrete. Present study mainly emphasizes on effectiveness of external GFRP strengthening for concrete beams and columns. Total five circular concrete columns of 320 mm in height and 160 mm in diameter, and 30 concrete rectangular beams with a section of 40 mmx40 mm and 160 mm in length. Two columns were control and the rest three columns were strengthened with three types of GFRP. For beams, fifteen of them was control and the others were strengthened by GFRP with U-shape. All the test specimens were loaded to fail in axial compression and strain for columns, and under three-point bending for beams. The test results clearly demonstrated that compared with the ordinary concrete, the axial load carrying capacity and flexural strength increase for the reinforced concrete no matter the kind of the GFRP used even if it was in different storage condition

Reliability Analysis in Performance-based Earthquake Engineering

AbstractThe performance-based engineering approach, as opposed to prescriptive rules of code-based design, is based on simulation of real structural behavior. Reliability of the expected performance state is assessed by using various methodologies based on finite element nonlinear static pushover analysis and specialized reliability software package.Reliability approaches that were considered included full coupling with an external finite element code based methods in conjunction with either first order reliability method or importance sampling method. The building considered in the actual study has been designed against seismic hazard according to the Moroccan code RPS2000

Development in Sustainable Concrete with the Replacement of Fume Dust and Slag from the Steel Industry

Nowadays, the reuse of waste is a challenge that every country in the world is facing in order to preserve the planet and introduce a circular economy. The chemical composition of some steel waste suggests that there are potentially appropriate substances for reuse, since this type of slag undergoes a process similar to that of cement in its manufacture. The advantages for the environment are obvious, as it valorises waste that is deposited in landfills. This paper studies the field of stainless steel, because its composition is different from that of carbon steel, and the replacement of cement with material or waste produced in the manufacture of stainless steel in a concrete matrix. This paper presents the results of replacing 25% of cement with material or waste produced in the manufacture of stainless steel in a concrete matrix whose values in the substitutions carried out were around 21% and 25% in terms of increased resistance capacity. These results have been obtained by carrying out tests, in terms of both strength and environmental capacity, allowing us to determine viable applications for the use of steel waste to improve the performance of cement or at least match it

Influence of bonded length of the Carbon Fiber Reinforced Polymer Plates on the behavior of a concrete beam

Sometimes Aged or Damaged Structures need to be reinforced and retrofitted to enhance their performances and structural life, for this reason, the rehabilitation has been the subject of extensive research. The strengthening Reinforced Concrete structures is one of the most difficult and important tasks of civil engineering. Among the ways used to strength the concrete; the reinforcement using Carbon fiber reinforced polymer. This material has proved to be more efficient than other composites because of its high elastics modulus, its durability and this kind of materials are less affected by corrosive environmental conditions. The technique used in this study will be the external bonding of Carbon fiber reinforced polymer (CFRP) to a concrete beam. In this paper, the focus will be on the influence of bonded length of the CFRP Plates on the global behavior of the beam. The study is developed by the finite element program ABAQUS and will contain 11 specimens with a dimension of 100*200*1000mm and the length of the CFRP will be 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, and a fully reinforced beam. Numerical results are presented and discussed herein

Numerical Modeling of Soil Erosion with Three Wall Laws at the Soil-Water Interface

In the area of civil engineering and especially hydraulic structures, we find multiple anomalies that weakens mechanical characteristics of dikes, one of the most common anomalies is erosion phenomenon specifically pipe flow erosion which causes major damage to dam structures. This phenomenon is caused by a hole which is the result of the high pressure of water that facilitate the soil migration between the two sides of the dam. It becomes only a question of time until the diameter of the hole expands and causes destruction of the dam structure. This problem pushed physicist to perform many tests to quantify erosion kinetics, one of the most used tests to have logical and trusted results is the HET (hole erosion test). Meanwhile there is not much research regarding the models that govern these types of tests. Objectives: In this paper we modeled the HET using modeling software based on the Navier Stokes equations, this model tackles also the singularity of the interface structure/water using wall laws for a flow turbulence. Methods/Analysis: The studied soil in this paper is a clay soil, clay soil has the property of containing water more than most other soils. Three wall laws were applied on the soil / water interface to calculate the erosion rate in order to avoid the rupture of such a structure. The modlisitation was made on the ANSYS software. Findings: In this work, two-dimensional modeling was carried of the soil.in contrast of the early models which is one-dimensional model, the first one had shown that the wall-shear stress which is not uniform along the whole wall. Then using the linear erosion law to predict the non-uniform erosion along the whole length. The previous study found that the wall laws have a significant impact on the wall-shear stress, which affects the erosion interface in the fluid/soil, particularly at the hole's extremes. Our experiment revealed that the degraded profile is not uniform. Doi: 10.28991/cej-2021-03091742 Full Text: PD

Seismic Retrofitting: Reinforced Concrete (RC) shear wall versus Reinforcement of RC element by Carbon Fiber Reinforced Polymer (CFRP) using PUSHOVER analysis

Seismic retrofitting of constructions vulnerable to earthquakes is a current problem of great political and social relevance. During the last sixty years, moderate to severe earthquakes have occurred in Morocco (specifically in Agadir 1960 and Hoceima 2004). Such events have clearly shown the vulnerability of the building stock in particular and of the built environment in general. Hence, it is very much essential to retrofit the vulnerable building to cope up for the next damaging earthquake. In this paper, the focus will be on a comparative study between two techniques of seismic retrofitting, the first one is a reinforcement using carbon fiber reinforced polymer (CFRP) applied to RC elements by bonding , and the second one is a reinforcement with a shear wall. For this study, we will use a non-linear static analysis -also known as Pushover analysis - on a reinforced concrete structure consisting of beams and columns, and composed from eight storey with a gross area of 240 m², designed conforming to the Moroccan Seismic code[1]

Seismic Retrofitting: Reinforced Concrete (RC) shear wall versus Reinforcement of RC element by Carbon Fiber Reinforced Polymer (CFRP) using PUSHOVER analysis

Seismic retrofitting of constructions vulnerable to earthquakes is a current problem of great political and social relevance. During the last sixty years, moderate to severe earthquakes have occurred in Morocco (specifically in Agadir 1960 and Hoceima 2004). Such events have clearly shown the vulnerability of the building stock in particular and of the built environment in general. Hence, it is very much essential to retrofit the vulnerable building to cope up for the next damaging earthquake. In this paper, the focus will be on a comparative study between two techniques of seismic retrofitting, the first one is a reinforcement using carbon fiber reinforced polymer (CFRP) applied to RC elements by bonding , and the second one is a reinforcement with a shear wall. For this study, we will use a non-linear static analysis -also known as Pushover analysis - on a reinforced concrete structure consisting of beams and columns, and composed from eight storey with a gross area of 240 m², designed conforming to the Moroccan Seismic code[1]