Appraisal of Bearing Capacity and Modulus of Subgrade Reaction of Refilled Soils

Muhammad Usman Arshid,M. A. Kamal

doi:10.28991/cej-2020-03091606

Muhammad Usman Arshid, M. A. Kamal

Open Access

https://doi.org/10.28991/cej-2020-03091606

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Abstract

Soil is remoulded, replaced, or improved in place to meet the required engineering properties. Relative compaction is the measure of the resulting engineering improvement. But design engineers need the allowable bearing capacity while the modulus of subgrade reaction is the primary input of modern foundation design software. The current research appraised a correlation between Relative Compaction ( ), Moisture Content ( ), and allowable bearing capacity ( ) and another correlation between , RC, MC, and modulus of subgrade reaction ( ). The test samples were extracted from each trial of the standard proctor test using purpose-built extraction tubes. Allowable bearing capacity has been determined by performing unconfined compression tests on the extracted tubes. The relationships have been established employing statistical analysis. It was noticed that soil samples at the lower moisture content (6-9%) show brittle failure before reaching the allowable strain. The soil samples having a moisture content of 10-14% exhibited shear failure, nearly simultaneous to the allowable strain. The soil samples having higher moisture content undergone a strain of 15% without showing the shear failure. A simple equation has also been appraised to determined Ks involving the three-input variable, i.e., , , and . Moderate correlations have been found to exist between the studied parameters, owing to some other variables' influence. Recommendations for future studies have been drawn to quantify the effect of identified parameters. Doi: 10.28991/cej-2020-03091606 Full Text: PDF

Highlights

The migration of population towards cities due to the lack of basic facilities in the rural areas of developing countries exerts extraordinary pressure on the recipient cities' infrastructure
The question arises that for the relative compaction of 95% or 98% of refilled material, what is associated allowable bearing capacity/modulus of subgrade reaction of the improved/compacted soil? The current study aims to fill the literature gap associated with refilled and re-compacted soils' bearing capacity
This study aims to find a correlation between the relative compaction (RC ), qall, and Ks for fine-grained soils

Summary

Introduction

The migration of population towards cities due to the lack of basic facilities in the rural areas of developing countries exerts extraordinary pressure on the recipient cities' infrastructure. Due to the multiplying growth of the population, agriculture and barren lands are converted into residential and commercial entities. The barren lands in the vicinity of Islamabad, Pakistan, and Pothohar Plateau have badland topography. The topography is being altered to convert these lands into residential units. The settlement of buildings and roads has become a norm in these developing lands. Compaction increases the soil density, enhances its strength, and reduces its compressibility and permeability. This modification's ultimate result is a significant increase in subgrade bearing capacity, minimizing the detrimental effects of a volumetric change (e.g., frost heave, swelling, shrinkage), and control of water flow (e.g., seepage, subsurface contaminant transport)

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