Papers by Keyword: Geogrid

Abstract: This article aims to study the Performance footing on loose sand soil reinforced with geogrid layers The Load Settlement behavior of the footing under various conditions such as different eccentric value (e), depth of the first geogrid layer (u/B), and vertical spacing between geogrid layers (z/B) was studied. This study presents, the numerical modeling utilizes the finite element package (PLAXIS version 8.2). The soil vertical stress displacement, axial force and footing displacement are discussed by means of a set of finite element results and the validation. The Load carrying decrease with increasing eccentricity values were shown. The optimal spacing between any successive reinforcement layer (z/B) is equivalent to (0.5) for different eccentricity value (e). The PLAXIS output show the failure mechanism developed, and maximum axial force that will be reached in geogrid and footing and the total stress distribution at failure.

Abstract: This paper deals with the problem of a flexible pipe with internal diameter of 110 mm buried in laboratory soil box facilities for this study. The box is filled with sand reinforced by geogrid layer of different widths to investigate the effect of geogrid width layer on the performance of buried pipe subjected to static load. Two type of reinforcement used (geogrid and geocell). The geogrid location is kept constant at a depth of 0.5d (do is o the pipe o diameter) below the loading plate. The results show that the reduction in crown strain in loose sand, when the geogrid width equals 1B iso13% in comparison with results of tests excluding geogrid, this percent reduces to 11% when the geogrid width equals 2B, while the reduction percent in medium sand becomes 14% and 12% when the geogrid width was B and 2B, respectively and becomes in dense sand 15 % and 11% when the width of geogrid change from B to 2B.

Abstract: An improvement of flexural strength of cement stabilized soils using geogrid designated as compacted cement-geogrid-sand (CCGS) is investigated in this research. The studied material performance of the CCGS includes postpeak behavior, toughness, and equivalent flexural strength ratio. The geogrid inclusion significantly improves the postpeak flexural behavior, which is a requirement for bound pavement materials. The first peak flexural strength f₁ and stiffness of both compacted-cement-sand (CCS) and CCGS are essentially the same for the same cement content. The tested soils were obtained from Ayutthaya province, Thailand, and is commonly used as a construction material for backfill and pavement applications. The backfill soils were used sand. In this study, Type I Portland cement was used as a cementing agent and geogrid two type were used as a reinforcement material. Properties of the cement and the geogrid, which were obtained from the manufacturers. The specimens were subjected to a flexural performance test according to ASTM C1609/C1609M-10 (2010). The results showed that in the flexural performance of the CCGS includeing postpeak behavior, toughness, and equivalent flexural strength ratio depends on the type and shape of apertures of the geogrid. It was found that the triaxial geogrid with shape of triangular apertures was more effective in reinforcing and provided the high equivalent flexural strength over uniaxial geogrid.

Abstract: The performance of flexible pavement depends mainly on the subgrade soil characteristics as it serves as a foundation for pavement. Roads constructed over poor subgrade soil fails frequently leading to heavy economic burden apart from high initial cost of construction. In order to overcome these problems soil reinforcement technique has to be adopted. The use of geosynthetic material is a new and emerging technique and is gaining importance due to cost and time saving apart from less environmental sensitive nature. In the present study an attempt has been made to make use of non-woven geotextile and biaxial geogrid in various combinations. The geogrid was placed above geotextile, both in layers from the top of mold and heavy compaction, soaked CBR and unconfined compressive strength (UCS) tests were performed. Scanning electron microscopy (SEM) images indicate significant bonding between soil particles and geogrid surface.

Abstract: The purpose of this paper is to describe (at micro-scale) the geogrid-reinforced flexible pavement behaviour under a static loading. The finite element technique is used to analyse the mechanical interaction between granular particles, asphalt binder and geogrid. The geogrid is the most commonly used geosynthetic product for enhancing the stiffness and stability of traditional flexible pavement and it is beneficial for reducing the rutting damage in pavement. The geosynthetic performance is influenced by geometry, material and its placement inside the pavement layers. Whereas, the asphalt mixture performance is governed by properties of aggregate (shape, size distribution, etc.), properties of asphalt binder (grading, viscosity, asphalt modifiers, etc.) and asphalt-aggregate interactions (adhesion and absorption, etc.). Through FEM software (ABAQUS) the microstructure is modelled in 3D. This microstructure is made up of three different components: spherical particles (aggregates), asphalt binder and one strip of geogrid.

Abstract: Roads are the most important component for the economic and social development of any country. India has a total road network of more than 6 million kilometers, which carry around 90% of passenger traffic and 65% of freight traffic. More than 20% land area of India is covered with soils having low California bearing ratio (CBR) and shear strength values. The pavement constructed over such soils will lead to rapid increase in construction and maintenance costs. This study presents a laboratory investigation about the combined effect of geotextile and geogrid reinforcement, placed in layers at various depths from top of specimen, on the strength behaviour of poor subgrade soil. Heavy compaction, soaked CBR and unconfined compressive strength (UCS) tests are conducted. The test results indicate significant improvement in CBR and UCS values for all geosynthetic reinforced cases, whereas ductility and rupture strength remains almost constant as compared to virgin soil. Scanning electron microscopy (SEM) analysis shows significant bonding between soil particles and fibers of geogrid, causing stress transfer from soil to reinforcing material and hence preventing soil from overstressing. It is concluded that combination of geogrid and geotextile can be used effectively for reinforcing poor subgrade soil.

Abstract: In article the calculation model of the reinforced crushed-stone-sand basis of pavement with the variable module of elasticity changing on layer depth on exponential dependence is offered. The calculation model is based on representation of the reinforced layer of granular material as the multilayered plate consisting of any quantity of the continuous layers which are rigidly connect among themselves. The method of calculation of the reinforced bases of pavement leaning on experimental data is offered. A concrete example of calculation is reviewed.

Abstract: Stamp tests results of the two-layer basis from the crushed stone and sand reinforced by geogrid with steel fibers in a plastic shell are given in report. Deformation characteristics of the reinforced design are received. Experimentally established deflections of the reinforced basis are compared with the results received theoretically. Thus the reinforced layer of crushed stone is considered as a multilayered plate on the elastic basis. Bubnov-Galerkin's method of calculation is used. Satisfactory coincidence of theoretical and experimental results is received. The effect of reinforcement on deflections is established.

Abstract: Compared with pile-supported reinforced embankments, rigid-flexible pile composite foundation with geogrid reinforced cushion (RFPCFGRC) has its advantage of its economics. Piles play an important role in rigid flexible pile composite foundation with geogrid reinforced cushion. The bearing mechanics of RFPCFGRC is more complicated than that of pile-supported reinforced embankments because of addition of flexible piles. This paper discussed the diffence and the bearing mechanics of the two types of composidte foundation. The results show that addition of flexible piles has changed bearing mechanics of composite foundation and changes the load distribution among piles and soil. Soil arching degree of RFPCFGRC is larger than that of pile-supported reinforced embankments.

Abstract: The strain measurement is a most important and absolutely necessary task on the probing into the constitution of the materials. The ways of strain measurement are theoretically divided as the mechanical type, vibrating-string type, inductive type and bonded resistance type, and the last one is widely used for its high precision and convenience. The geogrid, which has been widespread in the reinforcement structures, is more and more popular for its high strength, good toughness, corrosion resistant, anti-fatigue and effective interaction with soil. The geogrid is made of polymer, its ultimate strain can reach above 10%, and it is sensitive to the time, furthermore it usually has significant relative displacement with soil in the tests. Then some measures have to be taken to make the measuring range wider and make the all gauges achieving synchronization, measures also should be conducted to prevent the strain gauges separated from the geogrid when it has slightly bending, prevent the wires break when the gauges going forward and reduce the influences from the forward preventing measures. Some researchers have showed their techniques to avoiding part of the above problems. Based on a series of pullout tests of geogrid, this paper gives the contrast and analysis on those techniques above, and lists the relative measures that used in these tests, especially for the gauge sticking techniques and preventive measures.