Effect Of Geogrid Research Articles

A Study on Effect of Geogrid Reinforced- Crushed stone Sub-base in Permeable Pavement System

A rapid urbanization has increased the portion of paved layer that results in the change of water circulation system. This change leads to frequent events of flooding, drought, and urban heat island. To resolve these issues, permeable pavement system based on Low Impact Development (LID) concept is being applied to international urban areas. Therefore it is necessary to establish a rational design procedure for the permeable pavement system that reflects our environmental conditions. iDue to inherent characteristics of permeable pavement system, water infiltrates thorough the layers so it may reduce the bearing capacity of sub-layers. In this study, an effort was made to investigate the effectiveness of geogrid reinforced crushed stone subbase layer based on field experimental program along with a limited numerical analysis. It reveals that geogrid reinforced sections improve the bearing capacity by close to 20%. In addition, a light weight deflectomenter (LWDT) appears to be promising for the compaction quality control of crushed stone subbase layer in order to construct qualified permeable pavement systems.

Mechanistic-empirical approach to characterizing permanent deformation of reinforced soft soil subgrade

This study focuses on characterizing the permanent deformation of geogrid-reinforced soft soil subgrade by using the mechanistic-empirical (ME) approach based on both experimental measurements and results of numerical modeling. Two sets of small-scale pavement sections were built over two types of soft soil subgrade and subjected to cyclic moving loads by means of a reduced-scale accelerated pavement testing (APT) device. Each set of pavement sections included one control section and three sections reinforced by different geogrids placed at the base–subgrade interface. The pavement sections were instrumented to measure vertical deformation and vertical stresses at the top of the subgrade. Strains developed in the geogrids were also measured by strain gauges throughout the construction and accelerated testing. Simplified finite element (FE) models were created to simulate both the control and geogrid-reinforced pavement sections and to compute the pavement mechanistic responses. With the experimental measurements from the first set of tests and results of FE analysis, the permanent deformation model in NCHRP 1-37A for unbound layers was adapted and calibrated to model the permanent deformation of the geogrid-modified subgrade. The effects of geogrids on the subgrade permanent deformation were integrated into the ME performance model through both the mechanistic response modeling and the empirical calibration. Predictions from the permanent deformation model were then compared with the second set of measurements and found to underestimate the permanent deformation of the geogrid-modified subgrade. However, the model was able to distinguish the difference in performance among the sections, i.e. the predicted rank of the performance was consistent with the measurements.

Effectiveness of Geogrids on Rutting and Bearing Capacity of Sub-base Course

Geogrids are being used in transportation application often in embankment construction due to their ease of construction and economy compared to traditional methods. Utilizing polymer materials in order to improve the performance of road structure is based on two factors, decreasing deformation and increasing bearing capacity. In this study geogrids were tested to check the ability of increasing load carrying capacity for highway projects. The purpose of this research work was to find a relation between the loading of the geogrid, the thickness of the aggregate layer and its bearing capacity. This would normally lead to an investigation on the lateral restrain behavior of a geogrid. According to the results obtained from soil mechanics laboratory, it could be demonstrated that by utilizing geogrids , the probability of occurring rutting decreases 30% and the bearing capacity of soil increase 40 % respectively.DOI: http://dx.doi.org/10.3126/njst.v15i1.12020 Nepal Journal of Science and TechnologyVol. 15, No.1 (2014) 77-80

Experimental study on performance of multidirectional geogrid and its application in engineering of high slope

By analyzing the grille mechanical property, tensile strength and creep tests, and the field tests, we investigated the characteristics and the reinforcement principle of multidirectional geogrid, and obtained the effect factors of grid characteristics, load and time curve and the shear stress of grille and sand interface. The reinforcement effect of geogrid in combination of typical project cases was illustrated and the following conclusions were presented. Firstly, multidirectional geogrid has ability to resist structural deformation, node distortion or soil slippage under stress, and can effectively disperse load. Secondly, with the increase of tensile rate, grille intensity increases and the creep value also increases with the increase of load. Thirdly, the frictional resistance balance between horizontal thrust of damaged zone and reinforced soil in stable region can avoid slope failure due to excessive lateral deformation. Fourthly, the multidirectional geogrid is able to withstand the vertical, horizontal and diagonal forces by combing them well with three-dimensional orientation, realizing the purpose of preventing soil erosion and slope reinforcement, which has a wide range of application and development in engineering field.

Analysis of Engineering Application about Reinforced Earth Retaining Wall

Geogrids reinforced soil retaining walls are widely used in various fields, such as highway, railway, architectural engineering, hydraulic engineering and so on because of its remarkable economical benefits, constructing convenience, adaption to the foundation simplicity of foundation treatment good vibration resistance shapely configuration and environmental pollution-free etc. Combined with a real engineering, the applied effects of geogrids reinforced earth retaining was tested. Based on the field test results and finite element method numerical analysis, the engineering characteristics of blocking reinforced earth retaining wall that used lime soil as filled material in construction period and after completion were opened out. The distributing characteristics and rules of wall back lateral soil pressure, tensile bar pull were put forward. Thus, technical references were provided for the similar structures.

The lateral displacement response of geogrid-reinforced ballast under cyclic loading

Ballast being an unbounded granular medium spreads laterally when subjected to high-frequency cyclic loading. To reduce lateral movement of ballast and to optimize track performance, rail tracks can be reinforced with geogrid. In this study, a novel large-scale process simulation test (PST) apparatus that can capture the lateral strain variation upon loading is described. Laboratory tests were conducted to explore the deformation and degradation response of both unreinforced and reinforced ballast under high-frequency cyclic loading. Fresh Latite basalt having an average particle size (D50) of 35 mm, and geogrids with different aperture sizes were tested. The laboratory experimental results reveal that the ballast deformation (both lateral and vertical) and the breakage during cyclic loading are influenced by the geogrid type and its placement location. Moreover, the lateral strain profiles along the ballast depth have been measured and the geogrid influence zone (GIZ), defined as the distance to which the effect of geogrid in arresting the lateral displacement of ballast exists, has been determined. The GIZ is found to vary from 160 mm (4.60D50) to 225 mm (6.45D50) depending on the location of the geogrid. In addition, the optimum geogrid position in the track has been identified to be 65 mm above the subballast. The test results also exemplify the ability of geogrid to arrest lateral displacement of ballast, reduce settlement and minimize particle degradation under high-frequency cyclic loading.

Effects of Geogrid on Dynamic Strength Characteristics of Solani Sand

In this paper, the deformation behavior of Solani river sand and the effects of geogrid reinforcement under cyclic loads are investigated. The effects of dynamic loading parameters on Solani sand were determined in dry and saturated condition. The effects of geogrid on properties of sand were analyzed. Samples were prepared in a shake table having test bin of dimension 1.05 m × 0.6 m × 0.6 m. The shake table could produce horizontal vibration with various frequency and acceleration. Results on dry sand indicated that the volumetric strain varied as a function of acceleration and number of loading cycles. Volumetric strain of dry sand samples reduced significantly by reinforcing with geogrid sheets. The response of saturated samples under cyclic loading were observed. Samples reinforced with geogrids showed reduction in pore water pressure and settlement. The effects of number of cycles on volumetric strain and pore water pressure on unreinforced and reinforced samples were analyzed.

Test Research of Geogrid Reducing Pavement Rutting on Soft Foundation

The interior prototype rutting test is designed to research the effect of geogrid on reducing rutting. Three models are studied, which include unreinfored, Telegrid JBS20 and Tensar SS30. The change trend of rutting and the influence of differential structure geogrid on rutting are analyzed to evaluate the effect of geogrid on reducing rutting. The results of the tests prove that the geogrid reduce pavement rutting on soft foundation effectively, SS30 with higher node intensity and rigidity obviously exceeds JBS20 with higher tensile strength on the effect of reducing rutting, and the effect on reducing rut is not very good by improving tensile strength of geogrid.

Geogrid mechanism in low-volume flexible pavements: accelerated testing of full-scale heavily instrumented pavement sections

This study uses full-scale accelerated testing to provide new insight into the effectiveness of geogrids on the performance of low-volume flexible pavements. Although several previous studies reported that geogrids improve pavement performance by enhancing its structural capacity and reducing distress potential, this study goes further to quantify the effectiveness of geogrids, specify the mechanism of the reinforcement they provide and identify the optimum placement of geogrid in low-volume flexible pavements. Full-scale, low-volume flexible pavement sections were constructed on weak subgrade (California bearing ratio = 4%) and heavily instrumented with 170 sensors. The pavement was divided into three cells with each cell having three sections. The granular base and hot-mix asphalt layer thicknesses varied, and each cell had at least one control and one geogrid-reinforced pavement section. The instruments were embedded to measure stress, strain, deflection, moisture, pore-water pressure and temperature and were used to monitor pavement response to a moving load using the Accelerated Transportation Loading ASsembly (ATLAS). The testing programme was divided into two parts: response testing and performance testing. The response testing considered tyre configuration, loading, inflation pressure, speed and travelling offset. The performance testing considered number of passes to failure. This paper presents the various pavement responses to different loading configurations and pavement performances when a repetitive moving dual-tyre assembly at 8 km/h and 44 kN was applied. Based on the performance testing and visual observation of the pavement cross sections after excavation, the reinforced sections showed reduced rutting and delayed surface cracking compared to the control sections. Specifically, the pavements' measured response showed that geogrid-reinforced pavement sections exhibited less vertical pressure and less vertical deflection in the subgrade when tested at a low speed. Therefore, the study's most notable conclusion is that geogrid reinforcement reduces the horizontal movement of the granular material, especially in the longitudinal direction. The study also concludes the following about geogrid placement: (1) for a relatively thick granular base layer, placing the geogrid in the upper one-third of the base reduces the shear strains in the longitudinal and transverse directions. (2) For weaker pavements, the geogrid reinforcement at the base–subgrade interface reduces the vertical deflection. In the second case, the effectiveness of geogrid shall be compared to the increase in pavement structure or using other geosynthetic materials such as geotextiles.

Effect of geogrid in granular base strength – An experimental investigation

An attempt is made to investigate the change in strength characteristics of different granular base materials reinforced with geogrid. The samples tested were both soaked and unsoaked, with and without geogrid to simulate both the best and worse case scenarios. The present investigations focuses only an experimental investigation, but this can set a stage for the development of proper mechanistic design of geogrid reinforced granular base material. The results of the experiment provide guidance for what type of granular material can benefit from reinforcing it with geogrid.

Effectiveness of geogrids as inclusions in cover soils of slopes of waste disposal areas

This paper presents an experimental investigation on the use of geogrids buried in cover soils of slopes of waste disposal areas using a large-scale ramp test. The tests involved the use of geogrids with varying values of tensile stiffness and bearing capacity (number of bearing members) installed at different elevations above the geomembrane resting on the ramp surface. The influence of the use of a geotextile layer on the geomembrane on the behaviour of the system was also assessed. The results show that the presence of a geogrid in the cover soil, and particularly of a geogrid with a geotextile on the geomembrane, can significantly reduce the deformability of the cover soil and the tensile forces mobilised in the geomembrane, as well as increase the inclination of the slope at failure.

Laboratory and Case Study for Geogrid-Reinforced Flexible Pavement Overlay

The formation and development of fatigue cracks in asphalt concrete beams have been extensively studied. Among these studies, however, very few have focused on the effects of geogrids in enhancing the resistance of asphalt concrete to fatigue failure. In addition, findings and conclusions of those studies cannot be effectively applied to most situations in Taiwan. It is therefore necessary to study the formation and development of fatigue cracks in overlaid dense-graded asphalt concrete. Among geogrids used in this laboratory study, two were made of glass fiber with strength of 100 kN/m and 200 kN/m, respectively, and one was made of high-density polyethylene (HDPE) with a strength of 25 kN/m. A series of tests for a beam reinforced with glass geogrids of 100-kN/m strength showed a fatigue life 3 to 5 times that of an unreinforced beam; and for a beam reinforced with 200-kN/m glass geogrids, the fatigue life was 5 to 9 times as long. Beams reinforced with the HDPE geogrids showed a fatigue life equivalent to those reinforced with 100-kN/m glass geogrids. Based on the findings of the laboratory study, an on-site performance study was carried out at a section of the Taiwan Second Freeway (already open for operation) from 80 km 837.5 m to 81 km 262. 5 m. A 10-month rutting-depth measurement was obtained, which confirmed that the improvement from these geogrids over the fatigue life of the pavement overlay so far was obvious and significant.

Construction and Instrumentation of Geosynthetically Stabilized Secondary Road Test Sections

Nine instrumented flexible pavement test sections were constructed in a rural secondary road in southwest Virginia. The nine test sections, each 15 m (50 ft) long, were built to examine the effects of geogrid and geo-textile stabilization. Three test sections were constructed with a geogrid, three were built with a geotextile, and three were nonstabilized. The test section base course thicknesses ranged from 10.2 cm (4.0 in.) to 20.3 cm (8.0 in.), and the hot-mix asphalt (HMA) thickness averaged 8.9 cm (3.5 in.). Geosynthetic stabilization was placed on top of the subgrade layer. The pavement test sections were heavily instrumented with two types of pressure cells, soil and HMA strain gauges, thermocouples, and soil moisture cells. In addition, strain gauges were installed directly on the geogrid and geotextile. An extensive instrumentation infrastructure was constructed to locate all instrumentation, cabling, and data acquisition facilities underground. Instrument survivability has ranged from 6 percent ...

Construction and Instrumentation of Geosynthetically Stabilized Secondary Road Test Sections

Nine instrumented flexible pavement test sections were constructed in a rural secondary road in southwest Virginia. The nine test sections, each 15 m (50 ft) long, were built to examine the effects of geogrid and geo-textile stabilization. Three test sections were constructed with a geogrid, three were built with a geotextile, and three were nonstabilized. The test section base course thicknesses ranged from 10.2 cm (4.0 in.) to 20.3 cm (8.0 in.), and the hot-mix asphalt (HMA) thickness averaged 8.9 cm (3.5 in.). Geosynthetic stabilization was placed on top of the subgrade layer. The pavement test sections were heavily instrumented with two types of pressure cells, soil and HMA strain gauges, thermocouples, and soil moisture cells. In addition, strain gauges were installed directly on the geogrid and geotextile. An extensive instrumentation infrastructure was constructed to locate all instrumentation, cabling, and data acquisition facilities underground. Instrument survivability has ranged from 6 percent for the strain gauges mounted on the geotextile to 100 percent for the soil moisture blocks after 8 months of operation. The majority of instrument failures occurred either during construction or the first few weeks of operation. The data acquisition system is triggered by traffic passing over piezoelectric sensors and operates remotely. The corresponding data are transferred via modem to Virginia Polytechnic Institute and State University for processing. It is planned that the performance of the pavement test sections will be monitored for a minimum of 3 years.

The study on the confining effect of geogrid

The study on the confining effect of geogrid