Effects of 3D Geocells on Flexible Pavement Foundations

Abstract

The current below study examines the effects of adding a Cubic Three-dimensional Geo-synthetics material known as Geo-cells to the foundation layer of flexible Bitumen pavements. In this study, the test of California bearing ratio (CBR) of 5% is used to compare the steel reinforced and unreinforced pavement made sections built on that subgrade. To comprehend the impact of Geo-cell reinforcement upon the pavement section\'s load-carryings mechanism under static and repetitive loading circumstances, a number of model tests were conducted. The following characteristics were examined: surface deformation profile the test sections, real rut subgrade level, load-settlement response of the pavement sections, and pressure is transmitted into the subgrade soil beneath into the Geo-cell reinforced foundation layer.

Introduction

I. INTRODUCTION

Axle weights and traffic volume are both constantly rising, placing heavy pressures on the current road network. The tensions that are created between the layers quickly cause cracks to emerge, and any local differential settlements may cause the higher layers to settle later. These stresses cause local differential settling, or rutting, as well as the production of surface layer cracks (also known as fatigue). The types of soil found worldwide vary from very dense to very loose, and from rigid to very weak. Despite some soils being fragile, the availability of ideal construction sites is limited. Therefore, when these sites cannot be avoided, improvements must be made to them.

Geosynthetics have been used for several decades already. The use of geosynthetics has gained significant advantages over other improvement methods in recent decades, particularly in the pavement industry. The use of geocells in pavement layers has recently demonstrated significant performance improvement because they can add lateral confinement to the infill material in addition to the reinforcement functions offered by traditional geo-synthetics. When granular infill is applied over weak subgrades under monotonic loading circumstances, geocell reinforcement has demonstrated success. as demonstrated by numerous research studies in the past. Studies on flexible pavements under static and repetitive loads, with and without a geocell reinforced base layer However, the literature contains limited information about repeated stress testing with sophisticated instrumentation on pavement sections reinforced with geocells.

II. REVIEW OF LITERATURE

The study on geo-synthetic reinforced soil and pavement constructions under static and recurrent traffic loading is the subject of this chapter, which was conducted by a variety of practitioners and researchers. Studying how geocell reinforced pavements behaved under various load circumstances was the main focus.

As the main goal of this study is to comprehend the behavior of geocell mattresses under various loading circumstances, important papers on geocells are included.

An extensive body of research examined the possible application of geo-synthetics, including geo-grids, geo-nets, geo-textiles, composites, and geocells, as reinforcement in pavement layers for low traffic roads in order to mitigate the possibility of rutting phenomena. Typically, geosynthetic reinforced foundations and pavement constructions for static and repeated loads employ the bearing capacity improvement factor and traffic benefit ratio (TBR) as performance indicators. The total load repetitions for the reinforced beds must be divided by the total load repetitions for the unreinforced beds in order to determine the TBR for a specific rut depth.

III. METHODOLOGY

All paragraphs must be indented.  All paragraphs must be justified, i.e. both left-justified and right-justified.

The characteristics of the different type of materials utilized and the methods for sampled preparation employed in the current investigation are outlined. After a comprehensive discussion of the sample preparation techniques, the properties of the materials are presented. These resources serve as the foundation for the study.

1. Clayey sand is utilized for preparing the subgrade.
2. A base course made of wet mix macadam (WMM).
3. Macadam with bitumen as the top layer.
4. Geocell mattress provides reinforcement for the foundation layer.

The description of each material in further detail is covered below.

a) Atterberg’s limits

According to IS-2720 (Part4-1972), Atterberg's limitations, including into the liquid limit (LL) and plastic limit (PL), were conducted [33]. In Fig.3.2a, pictures of the testing equipment are shown. Figure 3.2b depicts the soil's flow curve. The soil's maximum tolerance for liquid and plastic is discovered to be 47% and 21%, respectively. The difference between LL and PL, or the soil's plasticity index, is calculated to be 26%.

According to the Indian Standard Soil Classification System, the soil is categorized as well-graded sand containing clay (SC).

b) Specific gravity

The specific gravity test is carried out in accordance with IS-2720 (Part3-1980) [34], and the result is 2.65. The results of this test, which was carried out using the density bottle method, are shown in Fig. 3.3.

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V. CASE STUDY

Several days of torrential rain at march 2016 completely destroyed a section of National highways no 44 (NH-44). The road is the main corridor for commercial used traffic in the state Tripura. The Road section is failed that was in the Assam side at Assam – Tripura Border area. A geocells is supported the road section was specified to repair the road which is damaged quickly. The region needed fast response. NH-44 road is essential and important transit role that meant any impassability meant spikes in fuels and food costs. The Geocell sheet solution was able to be applied in just 15-18 days from beginning of the construction works to reopening of roadways.

Conclusion

Considering cost is paramount in any civil engineering Endeavor. Upon examining the cost analysis presented in the previous chapter, it becomes apparent that for every kilometre of single-lane road construction, reinforced pavement entails a 10.15% reduction in costs compared to unreinforced pavement. Integrating geocell into the base layer results in a 43% reduction in base thickness compared to the unreinforced configuration. This reduction minimizes the demand for scarce virgin materials. Moreover, by enhancing the elasticity of the respective layers, geocell helps reduce the pavement\'s permanent deformations. In the reinforced scenario, there was a 13% decrease in total observed permanent deformation. The recorded rut benefit ratio (RBR) of 13% and rut depth reduction (RDR) of 19% demonstrate the geocell\'s effectiveness in distributing the load over a wider area, leading to reduced rutting at the subgrade level. Moreover, despite its reduced thickness, the reinforced pavement section exhibits greater stiffness compared to the unreinforced section, as indicated by the measured equivalent modulus improvement factor, which is 1.3 times higher than that of the unreinforced pavement section. AASHTO states that for the same traffic repetitions, the unreinforced pavement section should ideally have a thickness of 553 mm instead of 440 mm. The robust modulus of the base layer, computed in accordance with IRC norms, relies solely on the CBR of the subgrade. In contrast, AASHTO determines and designs the robust modulus of each layer based on actual acquired values, providing a more accurate approach compared to the IRC method.

References

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Copyright

Copyright © 2024 Chandrakant Soni, Dr. Bablu Kirar. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.