Effects of Soil Compaction in the Fight against Unpaved Roads Degradation Due to Erosion Caused by Heavy Rain: Proposition of a Specific CBR Evaluation Model

Ebenezer Njeugna,Timothée Thierry Odi Enyegue,Eric Flavien Mbiakouo-Djomo,Blaise Ngwem Bayiha,Fabien Kenmogne,Hugues Tsanga,Gilbert Tchemou,Didier Fokwa

doi:10.4236/eng.2021.133008

Abstract

Unpailt roads are generally subject to erosion, when they need to be bitumen, civil engineers need to know the geotechnical capabilities of the soil layers to be used as support, among these capabilities, for example, soil characteristics to withstand erosion. CBR has often been used to classify these soils according to their compaction. In this article, we propose a correlation between CBR and eroded soil mass through a simulator. Indeed, in this article we show that using a simulator, soils can be classified according to their ability to withstand water erosion, whether internal or external. Indeed it is shown that the mass of eroded soil is related to the compaction capacity of the soil just as the CBR also has. We study the effects and influence of soil compaction on the ability of an unpaved road to resist erosion caused by falling raindrops. To do this, lateritic soil is submitted to different compaction pressures. The compacted soil is then submitted to CBR test and rain fall through a mini rain simulator. Correlations between eroded soil masse and compaction pressure as well as CBR are derived. The study shows that the compaction reduces the erodibility and increases the bearing capacity of soil. The formula obtained is significant because we have a new way of evaluating soils in the laboratory.

Highlights

In African rural areas, in the forests and in some villages, non-bitumen roads are numerous and are exposed to erosion due to the rainfall of the regions, which causes a real problem when it is necessary to level regularly
Rain simulation methods are highly suitable for factor study trials, such as Jordan and Martinez studies, on surface runoff and sediment production on unpaved forest roads in the Los Alcornocales Nature Park using a simple portable rain simulator at an intensity of 72 mm∙h−1 and show the importance of vegetation cover, they advocate reducing the angle of the bank by about 40% and increasing the vegetation cover to 35% 40% to keep erosion below 18 g∙m−2 [1]
By observing the trend of other curves, we observe a linear growth with the increasing in the rainfall intensity. Another observation can be made through these different curves: The curves representing each degree of compaction are superimposed on top of each other, so that the lowest curves are those with the largest compaction

Summary

Introduction

In African rural areas, in the forests and in some villages, non-bitumen roads are numerous and are exposed to erosion due to the rainfall of the regions, which causes a real problem when it is necessary to level regularly. A better solution would be to properly fill these roads by using proper soil layers during construction With this in mind, rain simulation methods are highly suitable for factor study trials, such as Jordan and Martinez studies, on surface runoff and sediment production on unpaved forest roads in the Los Alcornocales Nature Park (southern Spain) using a simple portable rain simulator at an intensity of 72 mm∙h−1 and show the importance of vegetation cover, they advocate reducing the angle of the bank by about 40% and increasing the vegetation cover to 35% 40% to keep erosion below 18 g∙m−2 [1]. It sometimes happens in certain places that this layer is washed away during the rain, despite the ingenious techniques applied, that is the well-known erosion phenomenon [4] This is probably the reason why many researchers have put emphases on analytical and experimental studies of erosions dynamics, in order to predict or avoid them

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