Geotechnical Index Properties Research Articles

Effect of collated fly ash, GGBS and silica fume on index and engineering properties of expansive clays as a sustainable landfill liner

The effect of supplementary cementitious materials (SCMs) such as fly ash (FA), GGBS and silica fume (SF) on the geotechnical index and engineering properties of expansive clays (EC) are studied in this research work. This manuscript aims to determine the workability (consistency limits (CL)), swellability (free swell index (FSI)), compaction properties, strength characteristics (UCS) and hydraulic conductivity (HC) of varied eighteen mix proportions of FA-EC (P-series), FA-GGBS-EC (Q-series) and FA-GGBS-SF-EC (R-series) are experimentally studied as a bottom liner in landfills. From the test results, CL and FSI significantly decreased in P, Q and R series, this is due to the effect of flocculation, a process that increases the average particle size of mix blends and also depletion of the double-diffusive layer thickness of EC by promoting the Ca2+ ions in the pore water from SCMs. The compaction parameters such as optimum moisture content decreased in all the series, due to the higher flocculation of mixes. However, maximum dry unit weight increased in Q and R and decreased in the P series. The UCS values increased with an increase in optimum SCMs quantities and with curing intervals tested at 0, 7, 14 and 28 days. The higher UCS value is attained at 40 %FA with EC (i.e. P2), 60 %FA-GGBS with EC (i.e. Q3) and 60 %FA-GGBS-SF with EC (i.e. R3) in R-series which confirmed to be optimum due to the loss of cementation action/reduced cohesion in the matrix. In the case of HC, P2, Q3 and R3 mixes are confirmed to be optimum and fall under the criterion standards of landfill liner as per USEPA recommendation. Overall, this work proves to be a novelty and shows the feasibility of various collated SCMs blended with EC as landfill liner material, furthermore, these mixes are optimized to combine with EC to create a sustainable landfill liner that fits with the United Nations sustainable goals of 2030

Relationship between Geoelectrical and Geotechnical Index Properties of Soils

Relationship between Geoelectrical and Geotechnical Index Properties of Soils

Laboratory modeling and analysis of slopes of different geometry under the effect of precipitation

Back stability analysis, in-lab testing, and field tests may all be used to assess the behavior of stability of slopes. Each of these approaches has benefits and drawbacks compared to one another. Amongst these approaches, laboratory modeling stands out with its ability to prepare identical samples, keep external conditions under control, and measure deformations precisely. In this study, laboratory-based slope models at 1(Horizontal)/1(Vertical), 2/3, and 1/3 angles including the effects of precipitation and external loading were created. The results of these models were compared with those of the Plaxis 2D software. First, models were built using highly permeable cohesionless coarse-grained soils, and mixtures containing high plasticity clay (bentonite) at different rates were then prepared to investigate the effect of fine-grained soils on stability. Laboratory tests such as sieve analysis, specific gravity, consistency limits, Standard Proctor, and direct shear were used to assess the geotechnical index and mechanical properties of soils. Incremental surcharge loads were placed on the slope models and surface deformations, and local and general collapses under the effect of precipitation were observed. Laboratory model results highlighted that the fines content had a non-negligible effect on stability. When the slope behaviors were examined, it was observed that the models with a 1/3 slope had more severe local fractures and collapses. The stability of the slope is negatively affected when bentonite content in soil mixtures rises. The results of Plaxis 2D analysis are compatible with those of laboratory model tests and the factor of safety values obtained from Plaxis 2D range from 0.98 to 11.4.

Geotechnical Properties of Foundation Subsoils in Parts of Port Harcourt City, Obio/Akpor and Ikwerre Local Government Area, Rivers State, Nigeria

The study was carried out with the objectives of determining the stratification, geotechnical index properties of the soils in part of Port Harcourt city and Obio/Akpor local Government Area, Rivers state. Field Exploration and laboratory studies of soils samples were obtained from 0-20.25m deep. Subsurface soil profiles were delineated followed by determination of their index and mechanical properties, including Atterberg limits, particle sizes distribution, undrained shear strength, shear box test and consolidation coefficient. Results reveal an overlying light brown sandy clay, soft to firm consistency, clay thickness vary from 9.0 to 13.5m. Beneath this overburden lie yellowish brown to light grey fine to medium to coarse grained sand, loose to medium dense to dense consistency and poorly graded sand, thickness vary from 6.75 to 11.25m. The clays show low to intermediate clay plasticity (CL-CI). The shear strength parameters of these c- soil gave values range of 40-60KN/m2 . Allowable bearing capacities for the shallow foundation and bored pile foundation analysis was also carried out for the soil profiles with diameter 306, 406, 460 and 600mm for the deep foundation for various study areas were calculated.

The statistical sensitivity of highway project cost to geo-heterogeneity in the tropics

PurposeThe study is carried out to analytically reconnoiter geotechnical index properties of subgrade soils as key variables that shape the cost profile of road infrastructure projects in a tropical geographic setting with starkly heterogenous ground conditions.Design/methodology/approachUsing the Niger Delta region, as a point of reference, data on geotechnical index properties of subgrade soils at spatially dispersed locations for 61 completed highway projects are collated. Exploratory statistical tests were carried out to infer significant associations with final project costs before regression analysis. Regression analysis is principally deployed as an explanatory analytical tool, relevant to quantify the sensitivity of highway project costs to the individual and collective impact of geotechnical variables.FindingsSeveral parameters of expansivity and compressibility exhibited significantly strong associations with the final costs recorded on the highway projects. The statistical analysis further established a cause-effect relationship, whereby small changes in the geotechnical properties of sub-grade soils at project locations, would result in disproportionately large changes in the cost of road construction.Practical implicationsThe study findings provide insight into the sensitivity of road construction costs to geotechnical variables, which can serve as a useful input in financial risk analysis for development appraisal and the generation of location adjustment factors.Originality/valueThe study statistically demonstrates location-induced construction cost profiles, triggered in response to the spatial geotechnical variability and occurrence of problem subgrade soils in the humid tropics, which may be different from those traditionally established in studies of cold and temperate climate soils.

A General Overview on the Correlation of Compression Index of Clays with Some Geotechnical Index Properties

A General Overview on the Correlation of Compression Index of Clays with Some Geotechnical Index Properties

Characterization and Classification of Geotechnical Index Properties of Shallow Soil Deposits at Oworoshoki Area, Kosofe Local Government, Lagos, Nigeria

The study of geotechnical index properties of soils in Oworoshoki, Kosofe, Lagos State was conducted to characterize and classify the index properties of soil samples. Disturbed and undisturbed soils were collected at different shallow depths (1m, 2m and 3m) from the study area and laboratory test was conducted. The laboratory test conducted includes natural moisture content, atterberg limits (liquid limit and plastic limit), particle size distribution, specific gravity, unit weight and hydrometer. The results of the test were gotten: natural moisture content as 23.5%, 24.5% and 25.3% , liquid limits (LL) 28.68%, 26.64% and 29.10%, Oworoshoki is non-plastic for the three depths i.e. plastic limit (PL) is 0, particle size distribution percentage passing through BS #200 (0.075mm) are 95.97 %, 97.97%, 98.10% and this shows that the soil sample contain much silt, the samples are non-plastic for all depths (1m, 2m and 3m), specific gravity as 2.61, 2.55 and 2.60, unit weight as 17.5 KN/m3, 18.1kn/m3 and 18.9KN/m3 and hydrometer percentage passing through BS #200 (0.075mm) as 95.97% at 1.0m depth, 97.97% at 2.0m depth and 98.10% at 3.0m depth. Hydrometer test was conducted because 95.97% passes sieve 0.075mm.This shows that the soil contain high amount of silt. Soils from depth 1.0m, 2.0m and 3.0m are non-plastic (NP) because the Plastic Index (PI=0) and the soil samples are classified as A – 3 according to American Association of State Highway and Transportation Officials (AASHTO) System.

Investigation of the Influencing Soil Parameters on the Air Entry Values in Soil-Water Characteristic Curve of Compacted Heaving Soils

The air-entry value (AEV) is a fundamental parameter of the soil-water characteristic curve (SWCC). AEV is the minimum matric suction value required for entry of air into soil voids. The primary objective of this research work is to assess the impact of geotechnical index properties, swelling properties, mineral composition on AEV of compacted heaving soils, and discuss how they affect AEV. Soil properties were investigated through lab tests such as grain size distribution (GSD), specific gravity, Atterberg limits, linear shrinkage, free swell index, free swell ratio, X-ray diffraction, compaction test, and soil suction measurement. SWRC Fit program was used to perform non-linear fitting of the SWCC based on models VG, DB, FX, LN, and BL. Surface plot of data was used to characterize the impact of soil properties on AEV. It was observed that AEV is ranging from 10 kPa to 20.20 kPa, models DB and BL gives the best fitting SWCC. The percent of smectite mineral exhibits a significant impact on AEV. Swelling properties such as free swell index and free swell ratio influence the AEV with a respective determination coefficient of 85.72%, 88.68%. The plasticity index, linear shrinkage, specific gravity, and dry unit weight impact the AEV with a respective determination coefficient of 95%, 95.45%, 90.43%, 94.29%. The fine-grained content, clay fraction, void ratio, and water content influence the AEV with a respective determination coefficient of 97.95%, 84.89%, 80%, 94.31%. The finer the soil, the higher the AEV. The activity of clay and percent of illite mineral exhibit a marginal effect on the AEV.

Assessment of Quality of Some Laterites in Northeastern Nigeria by Multivariate Analysis of their Geotechnical Index Properties

The index properties of lateritic soils derived from sandstone, limestone, gneiss, granite, basalt, and migmatite in northeastern Nigeria were assessed for selecting the type with the best engineering potentials. The laboratory test results indicate that the tested samples comprised predominantly sand-sized particles (58–88%), with clay fraction (2–12%) of low to moderate plasticity (liquid limit, LL 35–49 and plasticity index, PI 12–24). Other geotechnical properties are as follows: natural water content (Wn), specific gravity (SG) 2.51–2.68, maximum dry density (MDD) 1.69–2.05 mg/m3, and unconfined compressive strength (UCS) 20–43 kPa. Principal component analysis reveals three significant factors. The first factor has loadings from clay, LL, PI, Wn, and SG, indicating impacts that are mineralogical and particulate constituent related. The second has loadings from gravel, MDD, and UCS and indicates textural influence, while the third factor has loadings from silt and sand, thus, reveals textural impact. The analysis of variance result reveals a significant difference in dataset, while cluster analysis indicates three different sample clusters, with a granite laterite sample representing the central object of the first cluster and sandstone and limestone laterite samples representing central objects of the second and third clusters, respectively. Comparatively, the second cluster samples would likely perform best in engineering projects having recorded comparatively the least clay content, lower plasticity, highest SG, MDD, and UCS. Thus, a combination of index properties and multivariate analysis proves a useful tool in the geotechnical prospecting for lateritic soils.

Chemical, Mineralogical and Geotechnical Index Properties Characterization of Volcanic Ash Soils

Soils derived from volcanic ash are deposits formed from the weathering of the ejected material during volcanic activity. Volcanic ash is commonly known in geotechnical engineering as a difficult and unwanted material. The difficulties are related to the high-water content, high liquid limits, low unit weights, and high void ratios, which translates into possible engineering problems (e.g. compressibility and collapsibility). The characterization of these materials is important because volcanic soils represent 0.84% of the terrestrial soil surface, 60% of which are located in tropical zones. These percentages represent areas with a high human population and constant demographic and economic growth. This paper presents the chemical, mineralogical and geotechnical index properties characterization of soils derived from volcanic ashes through laboratory testing and compares them with the results found in the literature. The SEM results shows the high void reported in the literature. The index properties obtained coincide with the ranges reported. However, lower values of dry unit weight were observed, which are related to the transportation processes of the particles and with higher index properties values due to mineralogical components such as allophane. Therefore, the study of volcanic ash soils requires a rigorous knowledge and understanding of the soil formation, depositional environment, and mineralogy. The chemical characterization of the volcanic ash plays an important role to understand water retention characteristics and their influence on the different geotechnical properties.

Permafrost geotechnical index property variation and its effect on thermal conductivity calculations

Geotechnical borehole and sample data from three databases compiled by the Geological Survey of Canada were analyzed to determine the variability of geotechnical index properties within frozen soils. The analysis included 2662 boreholes with geological setting data, up to 60 m depth, within the Mackenzie Valley and Delta region of the Northwest Territories. A total of 7539 samples, each with soil and ice classifications and gravimetric moisture content data were included. Gravimetric and volumetric moisture contents were analyzed by general soil type to determine their coefficient of variation (COV) with depth and geologic setting. As expected, variability between geologic settings corresponded to the nature of the soil's depositional environment, and volumetric ice content variability decreased with increasing depth. General soil type was also used to determine the COV for dry density, specific gravity, and Atterberg limits for samples where testing was available. The variability of frozen thermal conductivities was estimated using Monte Carlo simulation and common equations from the literature based on the geotechnical index property variation. Recently-derived equations for thermal conductivity showed less variability compared to earlier methods.

The Influence of Organic Matter Content on the Rheological Model Parameters of Soft Clay

Soil samples with different organic matter contents and their geotechnical index properties were determined. With an improved direct shear creep apparatus, the rheological characteristics of the soil samples were tested under stepwise loading, and the strain-time curves (creep curves) under different loads were obtained. Based on the Nishihara model, a new nonlinear viscoelasto-plastic soil rheological model (improved Nishihara model) was proposed by introducing a nonlinear Hooke element, which is capable of reflecting the rheological properties of artificial soft clay and natural soft clay. The results of the fitting indicate that the organic matter content is an important factor in the creep behavior of soft clay, and there is a good correlation between the organic matter content and the rheological model parameters.

Geotechnical Index Properties of Soils in Abua and Environs: A Case Study of Obedum-Anyu-Emelago Road

The frequent collapse of engineering structure and in incessant cracks witnessed on walls of buildings within the Obedum-Anyu-Emelego axis of Abua/Odual Local Government Area of Rivers State prompted the need for geotechnical investigation to assess the suitability of soils and characterize their engineering properties as a guide to foundation designs. Soil samples were obtained between 0 and 30 metres depth and used in the study. The field boring and laboratory results shows that the stratigraphy is predominantly of medium with soft to firm brown mottle grey salty peaty clay and soft to firm grey mottle brown salty peaty clay in shallow borings of 2 m. The organic peaty clay layers are very poorly suited to support foundations due to very high compressibility compared to other materials. Laboratory analyses showed that the clays are characterized by moderately high moisture content and compressibility and fairly low undermined strength. CBR values between 5.7 percent to 8.5 percent, liquid limit between 38.8 percent and 50.6 percent, plasticity limit 18.8 percent and 25.5 percent. Comparison of these ranges of geotechnical properties with Bench Mark for sub grade indicated that they are of low standard. Recommendation includes the need for stabilization with lime and cement to avoid the collapse of structure or buildings within the study area.

Geotechnics of municipal sludges and residues for landfilling

This paper presents a comprehensive review of reported field and laboratory investigations and theoretical work concerning the geotechnical behaviour/properties of water treatment residue (WTR), biosolids and sewage sludge materials, which are by-products of municipal water and wastewater treatment processes. After describing the backgrounds to the generation of these materials and various disposal options (with a focus on landfilling), including associated geotechnical issues, their physical, geotechnical index, compaction, undrained strength and effective-stress strength properties are described, including the effects of oxidation, biodegradation and viscous gel-like pore fluid for biosolids/sewage sludge material. Characteristic compressibility, consolidation and permeability behaviour/properties are also presented for these materials and linked with microstructure and the chemicals added during the treatment processes. The paper then focuses on various geotechnical issues pertinent to landfill (monofill) disposal of these materials, including undrained strength requirements, design strength, on-site and laboratory strength measurements and water content–strength correlations. Since such correlations are material specific, with the geotechnical properties of biosolids, sewage sludge and WTR materials varying between water/wastewater treatment plants, they cannot be applied more widely with confidence. Alternative approaches to predicting undrained strength are described, including a power–law strength relationship with water content, which can be applied more generally.

Geotechnical evaluation of Ankara clay as a compacted clay liner

This study investigates the geotechnical properties, and mineralogical and permeability characteristics of “Ankara clay” to evaluate its suitability as a compacted clay landfill liner material. The geotechnical index properties of the clayey soil samples collected from the western part of Ankara were determined. All the soil samples were tested for permeability by means of falling head compaction permeameter apparatus. The mineralogy of the soil samples were examined by X-ray diffraction and scanning electron microscope analyses. The cation exchange capacities of the soil samples were determined by the methylene blue adsorption test in order to determine the presence of swelling clay minerals in the soil samples. The influences of the geotechnical indices and mineralogy of Ankara clay on the hydraulic conductivity were investigated. Several landfill profiles containing various compacted clayey lining systems were simulated by the Hydrologic Evaluation of Landfill Performance model. All the soil samples tested led to hydraulic conductivities lower than the suggested regulatory limits (1 × 10−9 m/s) and therefore, are suitable to be utilized as compacted clay liners in potential sanitary landfill sites. Recommendations regarding field construction of the compacted clay liner are provided.

준설토의 간극비 변화 관찰을 위한 물리탐사기법의 적용

해성점토를 활용한 준설매립공사에서는 준설토의 거동분석이 선행되어야 한다. 본 연구에서는 침강압밀하는 준설토의 밀도와 간극비 변화를 관찰하기 위해 물리탐사기법을 적용하였다. 서해안에서 채취한 흙에 대한 기본물성시험을 실시하였고, 침강압밀시험기에 시료를 단계적으로 투기하여 시간에 따른 계면고와 탄성파의 변화를 관찰하였다. 흙의 침강압밀이 완료된 후 하방향의 투수시험을 실시하여 조간대의 영향이 준설토의 물리적 특성에 미치는 영향을 관찰하였다. 또한 초소형 전기저항탐침을 관입하여 깊이에 따른 시료의 전기비저항을 측정하였다. 모든 실험이 완료된 후, 시료를 채취하여 간극비를 계산하였다. 실험결과, ML 시료의 특성상 급격한 침강을 보여 침강압밀특성을 육안으로 관찰하기 어려웠으나, 단계투기가 계속될수록 탄성파의 속도는 증가하는 경향을 보였다. 하방향 투수에 따른 조간대 영향은 매우 적어 관찰할 수 없었다. 한편 탄성파 속도로 추정한 시료의 간극비는 단계투기에 따라 선형적으로 증가하는 경향을 나타내었다. 전기비저항으로부터 계산된 간극비는 깊이에 따라 반복적으로 증가, 감소하는 형태를 나타내었으며 이는 단계투기에 따라 층을 이루고 있는 시료의 영향으로 파악된다. 시료채취, 탄성파 속도, 그리고 전기비저항으로부터 구한 간극비를 비교한 결과, 서로 유사한 관계를 나타내었다. 본 연구는 물리탐사기법이 준설토의 간극비 관찰에 효과적으로 활용될 수 있음을 보여준다. It is necessary to understand the behavior of the soils for the dredging constructions. The objective of this study is to estimate void ratio and density changes of the dredged soils by using the geophysical testing methods. A series of laboratory tests is performed to obtain geotechnical index properties of the specimen, retrieved from the west coastal of Korea. The sedimentation and self-weight consolidation tests are carried out with observing changes of the interfacial height and the elastic wave velocities. The same amounts of the soils are poured into the testing column at intervals of 12 hours until the interheight reaches to a certain level. After the completion of the sedimentatation and self-weight consolidation tests, downward permeability test is performed to assess a tidal influence in the nearshore. The mini resistance cone is penetrated into the specimen to measure the electrical resistivity with depth. All tests are completely finished, the weight of specimens are measured to calculate the void ratio with the depth. Experimental results show that the aspects of the self-weight consolidation are invisible during dredging process because of rapid sedimentation characteristics of ML. However, the elastic wave velocities increase with increasing in the effective stresses. During permeability test, measured permeability and the elastic wave velocities maintain almost identical values. Void ratio based on the elastic wave velocities changes linearly with time during the step dumpings. Void ratio estimated by the electrical resistivity represents the repeatedly layered depositions according to the step-by-step dumpings. Void ratio determined by soil sampling is similar to those of elastic waves and electrical resistivity profiles. This experimental study demonstrates that the geophysical testing methods may be an effective method for evaluating the behavior of dredged soils.

The relationship between geotechnical index properties and the pore-size distribution of compacted clayey silts

Abstract In this study, the relationships between geotechnical index properties and the pore-size distribution of compacted natural silt and artificial soil mixtures, namely, silt with two different clays and three different clay percentages (10%, 20%, and 40%), were examined and compared. Atterberg’s limit tests, standard compaction tests, mercury intrusion porosimetry, X-ray diffraction, scanning electron microscopy (SEM) analysis, and Brunauer-Emmett-Teller specific surface analysis were conducted. The results show that the liquid limit, the cumulative pore volume, and specific surface area of artificially mixed soils increase with an increase in the percentage of clay. The cumulative pore volume and specific surface area with geotechnical index properties were compared. High correlation coefficients were observed between the specific areas and both the liquid limit and the plasticity index, as well as between the cumulative pore volume and both the clay percentage and the S coefficient. In addition, qualitative SEM analyses were conducted.

ALTERNATIF PONDASI TEROWONGAN LAYANG DALAM LAUT UNTUK PRASARANA TRANSPORTASI

A Submerged Floating Tunnel (SFT) is a tunnel that floats in water, supported by its buoyancy specifically by employing the hydrostatic thrust. In order to construct the foundation of the SFT, soil investigation has to be performed in advance. The soil investigation includes identification of subsurface soil profile, geotechnical index properties and parameters. Results of the soil investigation were used to he analyze and develop alternatives of the foundations for anchoring the prototype of the SFT. This paper discusses the alternatives of the foundations based on soil condition and applied tension leg. The research will be of interest to many practicing engineers and researchers regarding the subject matter.

Relationship between electrical resistivity and basic geotechnical parameters for marine clays

Recently, considerable efforts have been made in the attempt to map quick clay areas using electrical resistivity measurements. However there is a lack of understanding regarding which soil parameters control the measured resistivity values. To address this issue, inverted resistivity values from 15 marine clay sites in Norway have been compared with basic geotechnical index properties. It was found that the resistivity value is strongly controlled by the salt content of the pore fluid. Resistivity decreases rapidly with increasing salt content. There is also a relatively clear trend of decreasing resistivity with increasing clay content and plasticity index. Resistivity values become very low (≈5 Ω·m) for high clay content (>50%), medium- to high-plasticity (Ip ≈ 20%) materials with salt content values greater than about 8 g/L (or corresponding remoulded shear strength values greater than 4 kPa). For the range of values studied, there is poor correlation between resistivity and bulk density and between resistivity and water content. The data studied suggest that the range of resistivity values corresponding to quick clay is 10 to 100 Ω·m, which is consistent with other published limits. A comparison is made between two-dimensional electrical resistivity tomography (ERT) and resistivity cone penetration test (RCPTU) data for two of the sites and the two sets of data show similar trends and values irrespective of scale effect.

Inferring Hydrocarbon Migration and Sealing Potentials of Some Shales of the Anambra Basin (South-Eastern Nigeria) from Their Paragenesis and Geotechnical Index Properties

Shale samples from designated units of the Imo, Nsukka, Mamu, Enugu and Nkporo Formations of the Anambra Basin were subjected to X-ray diffraction and geotechnical index tests to determine the potential of the Formations to either create hydrocarbon migration pathways or to form seals for hydrocarbon entrapment. The X-ray diffraction results indicate that the shales are made up of silicate minerals with carbonates and sulphates. Results of the geotechnical index tests showed that the plasticity index (PI) for the Enugu shale ranges from 16 to 24 (average of 20) while the toughness index (TI) ranges from 0.4 to 0.8 (average of 0.7). The PI for the shales of Imo and Nsukka Formations ranges from 62 to 72 and 34–59 with averages of 67 and 46 respectively while their TIs range from 0.8 to 1.7 and 1.5–2.2 with averages of 1.3 and 1.9, respectively. These properties dispose the Enugu shale to easy amenability to loss of cohesion, deforming in a brittle manner, when subjected to shearing stress with the ability to create joints and faults that are pathways of hydrocarbon migration. Conversely, the properties of the shales of the Imo and Nsukka Formations give them the capacity to absorb high shearing stress without loss of cohesion thereby deforming in a ductile manner, which prevents the leakage of fluids in fluid migration. Hence, Enugu shale has the highest potential of creating hydrocarbon pathways while the shales of the Imo and Nsukka Formations are better seal rocks than others.