Abstract – September 2023 Issue

Experimental Behaviour of Nailed Soil by GFRP Bars

S. Sghaier, S. Ellouze, M. Bouassida, A. Bezuijen, B. Hadrich and A. Daoud

ABSTRACT: Replacing steel reinforcements with the inclusions of Glass Fiber Reinforced Polymer (GFRP) is one of the most promising solutions not only to overcome corrosion problems, but also to improve soil nail durability as a tool of slopes stabilization and retaining excavations. The present study provides an insightful knowledge regarding the pull-out behaviour of a GFRP nail observed in laboratory from a pull-out test. It is a parametric study, which includes the influence of nail dimensions, the overburden pressure, and the degree of saturation, essentially on the pull-out load of the GFRP nail. Using an experimental working method, based on a full factorial design, the study reveals that the influence of nail dimensions and the overburden pressure on the pull-out load are more significant than that of the degree of saturation. Moreover, the experimental results show that the pull-out behaviour of the GFRP reinforcement is different from the ribbed steel reinforcement, subjected the same testing condition. The differences between the Young’s modulus, the interface properties, and the surface roughness of the bar exhibit the main influence factors.

KEYWORDS: GFRP nail, Pullout test, Soil-nail interaction, and Design of experiments methodology.

Effect of Lime and Cement Kiln Dust on Strength Characteristics of Expansive Soil

D. Ashwini and H. N. Ramesh

ABSTRACT: The research objective is to study the potential use of cement kiln dust to advance the engineering characteristics of black cotton soil (BCS) in India, which covers about 20% of the country’s surface area. Cement kiln dust is an industrial waste that is difficult to dispose of and poses environmental risks, and the demand for cement is growing globally. The study aims to use laboratory tests to assess the impact of lime and cement kiln dust on the strength properties of BCS and to mitigate the excessive heave associated with the soil. The research methodology involves conducting Atterberg limit, free swell, compaction, and unconfined compression strength tests on BCS specimens treated with lime in incremental orders of 2% up to 10% of the dry weight of the soil sample. The optimum percentage of lime treated BCS sample treated with CKD in incremental order of 5% to 20% of dry mass of sample. 6% lime content was considered to be the optimum dosage with maximum UCS value for 7, 14 and 60 days and further on addition of CKD to lime treated BCS 6%lime + 15% CKD was found to be the optimum dosage with maximum UCS value for 7, 14 and 60 days.

KEYWORDS: CKD, Lime, Black cotton soil, and UCS.

Engineering Behavior of Soil Stabilized with Byproducts of Plastic Recycling Plant

V. P. Devipriya, S. Chandrakaran, K. Rangaswamy

ABSTRACT: Reutilization of waste materials in constructional activities is always preferable due to the economical point of view and as an environmentally friendly approach. Hence the use of recycled plastics as an additive in soils during constructional activities is an economic alternative for many soil improvement techniques. The main objective of this study is to improve the engineering properties of the soil samples with the addition of by products from plastic recycling plant. In this study two forms of by products (plastic flakes and pellets) produced during different stages of plastic recycling process is directly used as an additive for soil samples. The engineering properties of the soil samples randomly mixed with the recycled plastic materials are evaluated in the laboratory. Flakes and pellets form of high-density polyethylene plastics are mixed with the soil sample (0 to 2%) and the strength and compressibility properties of each sample are evaluated.
Consolidated undrained triaxial test and one-dimensional compression tests are conducted on each sample and the effect of the plastic addition is studied. From the test results it is observed that the shear strength of the sample was increased with the addition of plastic flakes and pellets addition. Compressibility parameters of the sample were reduced with the addition of recycled plastic into the sample. Maximum improvement in the engineering parameters were obtained with the addition of 2% of plastic flakes.

KEYWORDS: Recycled plastic materials, Soil stabilization, Shear strength characteristics, and Compressibility.

Performance Monitoring of Restraint Back-to-Back Mechanically Stabilized Earth Walls for Dam Crest Rehabilitation of Mae Suai Dam, Thailand

K. Wannasiri, S. Prempramote, and S. Soralump

ABSTRACT: The Mechanically Stabilized Earth walls (MSE walls) for dam crest rehabilitation was constructed at Mae Suai dam, Thailand. Welding mesh gabion was used as the facing on both sides, the polymetric geogrid and rebar were used as reinforcements. Furthermore, the MSE walls was placed on the original earth dam crest, steel sheet pile was installed at upstream and downstream side to prevent leakage and control the settlement of the new dam crest. The instruments were installed at various test sections to careful field monitoring to obtain high-quality data. The results obtained from 2D finite element method simulations were in good agreement with the field measurements, the lateral deformation and settlements were very small. The axial forces in rebar reinforcement were found to be continually changing due to deformation of foundation, external stimuli and construction factors. Likewise, the strain measured in all positions of geogrid reinforcement was very low. Combining steel reinforcement (high stiffness) with geogrid reinforcement (low stiffness) was redundant. Most of the lateral stresses are resisted by the former than the later. It can be concluded that in a reinforced soil wall that uses two or more types of reinforcing materials, tensile force is developed in higher stiffness material.

KEYWORDS: Dam crest rehabilitation, Dam crest raising, MSE Walls, and Reinforced earth embankment.

Recent Tendencies in the Use of the Response Surface Method in the Stability of a Synthetic Retaining Wall

M. Boutahir Born Bencheikh, A. Aidoud, S. Boukour, N. Handel, N. Khaldi, M. Dorbani and F. Z. Benarbia

ABSTRACT: Geogrids, a type of geosynthetic material composed of polymers, have found extensive use in transportation, infrastructure, and structural projects. They are commonly employed for soil stabilization purposes, ranging from reinforcing walls to strengthening subgrade soils or embankments. There is also a growing potential for geogrids to be utilized in remote sensing applications. To predict the horizontal displacement (Ux) and safety factor (Fs) of a synthetic retaining wall, finite element software is utilized for studying the impact of soil properties and reinforcement parameters, the vertical spacing between reinforcements (Sv), their length (L), and their normal stiffness (EA). The extent of influence from various factors is assessed through a grey relational grade analysis. Subsequently, the input layer parameters for the response surface methodology (RSM) of the central composite design (CCD) type are determined based on the outcomes of the grey relational grade analysis. The horizontal displacement and safety factor are predicted using numerical simulation with Plaxis 2D results.This paper presents a study of a synthetic retaining wall using an composite central type fractional digital experiment plan. The functional relationship between the output variables (horizontal displacement and safety factor) and the input variables (L, Sv, EA) was expressed with determination coefficients (R2 = 99.63% for Ux and R2 = 99.95% for Fs). These coefficients represent the ratio between the variation due to the model and the total variation. This high level of determination indicates that the model is well-fitted for both responses, confirming its adequacy. Therefore, central composite design models can be adopted to solve geotechnical problems, especially those related to synthetic retaining walls, which possess a highly complex and nonlinear structure.

KEYWORDS: Variance analysis, Identification of parameters, Optimization, Synthetic Support, and Reinforcement.

A Study on the Effect of Field Procedure Corrections of SPT- N Values on the Liquefaction Resistance of the Subsoil Strata along the Coastline of Visakhapatnam

C. N. V. Satyanarayana Reddy, S. Eswara Rao and A. Harika

ABSTRACT: The effects of liquefaction are often catastrophic, so evaluating the liquefaction potential of the subsoil strata is necessary to characterize their behaviour under dynamic loading, particularly earthquakes. Several laboratory tests are in use to evaluate the liquefaction potential of the soils. However, for improved accuracy, data from field tests are extensively being used to determine the liquefaction resistance of the ground. Over the years, several SPT- N-based methods were developed to assess the liquefaction resistance of sub-soils. Nevertheless, several studies reported the liquefaction potential of the soils without taking into consideration the field procedure corrections of standard penetration resistance (N), which may have a significant influence on the liquefaction evaluation. Hence, in the present study, the effect of SPT N field procedure corrections on the liquefaction resistance of the subsoil at the ten study areas selected along the coastline of Visakhapatnam is investigated. The Factor of Safety (FoS) against liquefaction is evaluated as per IS 1893(2016) and Idriss & Boulanger (2008) methods based on corrected and uncorrected standard penetration resistances and different input ground motions. The corresponding liquefaction potential indices (LPI) are determined from the Iwasaki et al. (1978) method to analyse the damage potential of the liquefaction. The study indicated that the field procedure corrections substantially affect the liquefaction resistance, as upon applying corrections to SPT N, the subsoil profiles at most study areas showed susceptibility to liquefaction, which are otherwise non-liquefiable.

KEYWORDS: Liquefaction, SPT N, Field procedure Corrections, Factor of safety, and Liquefaction Potential Index.

Land Reclamation Management Utilizing Artificial Intelligence for Estimating Soil Properties

T. Kumagai, T. T. T. Mai, K. Bai, F. Tsurumi, and T. Tashiro

ABSTRACT: In use of clayey soils for reclamation, the stability against slip and future consolidation settlement should be examined during and after reclamation. For these purposes, a practical reclamation management system has been developed based on three types of analysis: artificial intelligence (AI) estimation of soil properties such as compression index, consolidation coefficient and undrained shear strength, deposition shape analysis; and consolidation settlement analysis for clayey soils dumped from a hopper barge. The AI estimation of soil properties is characterized by use of a convolutional neural network (CNN) based on information such as soil source, wet density, and photographed image obtained before reclamation works. In this study, the validity of each analysis model has been verified on an actual reclamation project by use of measured data such as deposition shape of dumped soils on the seabed, soil properties in the reclaimed ground and consolidation settlement after reclamation and soil improvement.

KEYWORDS: Neural network, CNN, Machine learning, Centrifuge test, and CPT.