Evaluation of Pysicho-mechanical Properties of Clayey Soils Using Electrical Resistivity Imaging Technique

Evaluation of Pysicho-mechanical Properties of Clayey Soils Using Electrical Resistivity Imaging Technique
Author: Golam Kibria
Publisher:
Total Pages: 318
Release: 2014
Genre: Clay soils
ISBN:

Resistivity imaging (RI) is a promising approach to obtaining continuous profile of soil subsurface. This method offers simple technique to identify moisture variation and heterogeneity of the investigated area. However, at present, only qualitative information of subsurface can be obtained using RI. A study on the quantification of geotechnical properties has become important for rigorous use of this method in the evaluation of geohazard potential and construction quality control of landfill liner system. Several studies have been performed to describe electrical resistivity of soil as a function of pore fluid conductivity and surface conductance. However, characterization tests on pore water and surface charge are not typically performed in a conventional geotechnical investigation. The overall objective of this study is to develop correlations between geotechnical parameters and electrical resistivity of soil, which would provide a mean to estimate geotechnical properties from RI. As a part of the study, multiple regression analyses were conducted to develop practically applicable models correlating resistivity with influential geotechnical parameters. The soil samples considered in this study were classified as highly plastic clay (CH) and low plasticity clay (CL) according to Unified Soil Classification System (USCS). Based on the physical tests, scanning electron microscope (SEM), and energy dispersive X-ray spectroscopy (EDS) analysis, kaolinite was identified as the dominant mineral with some traces of magnesium, calcium, potassium, and iron. Electrical resistivity tests were conducted on compacted clays and undisturbed samples under varied geotechnical conditions. The experimental results indicated that the degree of saturation substantially influenced electrical resistivity. Electrical resistivity decreased as much as 11 times from initial value for the increase of degree of saturation from 23 to 100% in the laboratory tests on compacted clays. In case of undisturbed soil samples, resistivity decreased as much as sixteen fold (49.4 to 3.2 Ohm-m) for an increase of saturation from 31 to 100%. Furthermore, the resistivity results were different for the specimens at a specific degree of saturation because of varied surface activity and isomorphous substitution of clayey soils. In addition to physical properties, compressibility of clays was correlated with electrical conductivity. Based on the investigation, it was determined that the electrical conductivity vs. pressure curves followed similar trends as e vs. logp curves. Multiple linear regression (MLR) models were developed for compacted and undisturbed samples using statistical analysis software SAS (2009). During model development, degree of saturation and CEC were selected as independent variables. The proposed models were validated using experimental results on a different set of samples. Moreover, the applicability of the models in the determination of degrees of saturation was evaluated using field RI tests.

Evaluation of Geotechnical Parameters of Soil Using Electrical Resistivity Imaging

Evaluation of Geotechnical Parameters of Soil Using Electrical Resistivity Imaging
Author: Md Asif Akhtar
Publisher:
Total Pages: 218
Release: 2022
Genre: Engineering geology
ISBN:

Electric resistivity imaging (ERI) is an effective non-destructive and rapid measuring way of obtaining continuous soil subsurface resistivity profiles. An ERI technique can be used to identify moisture variations and soil heterogeneities in an area. Thus, ERI is becoming a popular tool in geotechnical (FHWA, 2015)engineering; however, it only provides qualitative information at the current time. Using qualitative images, it is challenging to extract quantitative geotechnical information, such as the type of soil, moisture content, degree of saturation, and atterberg limit, of the subsurface. Several studies have described the electrical resistance of soil as a function of pore fluid conductivity and surface conductance. Additionally, electrical resistivity measurements have also been made on commercial soils in order to determine the influence of geotechnical properties. Since a conventional geotechnical investigation may not perform characterization tests of porewater or surface charge, electrical resistivity must be correlated with geotechnical properties that can be tested in the laboratory. The objective of this experimental study is to investigate the relationship between the electrical properties of soil and geotechnical parameters of locally available soil and determine correlations between geotechnical parameters and electrical resistivity that can be used by geotechnical engineers. A study was conducted to study the electrical properties of soils obtained from 22 boreholesof four different locations, namely Fort-Worth, Beaumont, Corpus Christi, and El-Paso, selected based on their geological formation. Besides collecting soil samples through soil borings using the Texas Cone Penetration (TCP) method, a field, electrical resistivity survey was also conducted using 28 and 56 electrodes at the same locations to obtain a subsurface resistivity map. Field resistivity values were correlated with soil TCP values, and the correlation was compared to previous literature. In this study, 44 soil samples classified as low plastic clay (CL), 15 samples as high plastic clay (CH), and four samples as elastic silt (MH) were used to measure the resistivity of compacted clay soils. Furthermore, soil samples were categorized into six categories based on their liquid limit higher than 50, between 35 and 50, and lower than 35, and plastic limit higher than 25 and lower than 25 to investigate the changes in geoelectrical properties of soil. Various geotechnical conditions were used in laboratory tests to determine the influence of soil parameters on electrical resistivity. In both clayey soils and sandy soils, electrical resistivity measurements were found strongly influenced by the moisture content and degree of saturation. Soil resistivity was found to be averagely decreased by 80%, 43%, and 21% of initial value when the soil moisture content was increased from 10% to 20%, 20% to 30%, and 30% to 40% except for the soil samples contains liquid limit less than 50 and plasticity index higher than 25 for unit weight of 11.8 KN/m3.Soil resistivity was found to be decreased by 42%, 25%, and 41% for the above-mentioned water content due to the high activity of soil. Moreover, soil resistivity decreases 45% and 49% of the initial values when the unit weight increases from 11.8 KN/m3 to 13.4 KN/m3 and 13.4 KN/m3 to14.9 KN/m3. Soil resistivity decreases as much as 57-fold for normal clay and 7.5 fold for active clay from the initial value when the degree of saturation increased from 17% to 100%. However, the rate of change of resistivity is low when the degree of saturation of compacted clay is more than 50%. Furthermore, clay properties such as liquid limit and plasticity index also affect electrical resistance at different saturation levels. However, at a higher level of saturation, geotechnical parameters have less impact on electrical resistivity. The soil engineering properties of both sandy and clayey soils were correlated with electrical resistance using different multiple linear regression (MLR) models developed with R-studio. In developing a multiple linear regression equation for clayey soil, the degree of saturation and plasticity index were selected as independent parameters, while for sandy soil, moisture and sand content were used. Validation of the MLR models was based on field data, and therefore these models can be used for estimating engineering properties.

Determination of Geotechnical Properties of Clayey Soil from Resistivity Imaging (RI)

Determination of Geotechnical Properties of Clayey Soil from Resistivity Imaging (RI)
Author: Golam Kibria
Publisher:
Total Pages:
Release: 2011
Genre:
ISBN:

The use of resistivity imaging (RI) in the subsurface investigation has increased in recent years. RI is a non destructive method and provides a continuous image of the subsurface. Based on the electrical conduction phenomenon of soil, spatial and temporal moisture variation and heterogeneity of subsurface can be evaluated from RI. However, only qualitative evaluation of subsurface can be obtained from RI. The correlation between RI results and geotechnical engineering properties of soils has become an important issue for rigorous use of this method in site investigation. The current study attempts to develop the relationship and correlations between geotechnical parameters with electrical resistivity of soil. These correlations can be used for determining geotechnical properties from RI. Soil samples collected for the current study mostly consisted of medium to high plasticity clay with plasticity index more than 30. High energy X-Ray fluorescence (XRF) and scanning electron microscope (SEM) image analysis showed that the dominant clay mineral in the soil samples might be montmorillonite. The effects of moisture content, unit weight, degree of saturation, specific surface area, pore space, ion composition, compaction condition and fine fraction on soil resistivity were determined. Test results showed that soil resistivity decreased with the average rate of 13.8 Ohm-m for the increase of moisture from 10% to 20% at fixed unit weight. However, soil resistivity ranged from 2.1 to 2.42 ohm-m at 50% moisture content. Enhanced interaction between the clay particles and water and occurrence of ionic conduction reduced electrical resistivity with the increase of moisture content. Test results also indicated that soil resistivity decreased almost linearly with an average rate of 0.3 Ohm-m/pcf between moist unit weight 88.5 to 100 pcf at 18% moisture content. The average rate of reduction was 0.08 Ohm-m/pcf for further increase in moist unit weight in same moisture content. Reduction of interclod pores and better particle-to-particle contact might cause reduction in soil resistivity with the increase of unit weight. However, soil resistivity was more sensitive to moisture content than unit weight. In addition, average resistivity of the samples decreased from 6.7 to 3.2 Ohm-m with the increase of degree of saturation from 40% to 90% due to elimination of interclod macro pores, reorientation of clay particle and remolding of clay. Soil resistivity increased from 4.3 to 14.2 Ohm-m with the increase of specific surface area from 69.6 to 107.1 m2/gm at 18% moisture content and 75 pcf dry unit weight. Lack of formation of water film around the soil particle might restrict the current flow. Moreover, soil resistivity increased from 4.4 to 14.2 Ohm-m for the increase of pore space from 1.91% to 10.56% at 18% moisture content and 75 pcf dry unit weight and then decreased. Test results showed that soil resistivity increased from 4.3 to 14.2 Ohm-m with the increase of calcium ion from 8.3% to 13.9% at 18% moisture content and 75 pcf dry unit weight. Observed soil resistivity was high when samples were compacted at dry of optimum because of less pronounce bridging between soil particles. However, soil resistivity decreased when samples were compacted at wet of optimum. Near saturated voids and better interparticle bridging might caused the reduction in resistivity. Correlation of resistivity with unconfined shear strength of soil showed that soil samples prepared with moisture content below optimum, resistivity was high and strength was low. However, both resistivity and strength was low at moisture condition above optimum condition. In addition, soil resistivity were in between 3.16 to 3.6 Ohm-m for the increase of fine fraction from 66% to 94.8%. Therefore, the observed variation in soil resistivity with the fine content was not significant. Based on the study, it can be summarized that geotechnical engineering properties can be determined from RI under certain site specific conditions and moisture is the most influencing factor in electrical conduction.

Site Investigation using Resistivity Imaging

Site Investigation using Resistivity Imaging
Author: Sahadat Hossain
Publisher: CRC Press
Total Pages: 232
Release: 2018-08-06
Genre: Science
ISBN: 1351047590

Subsurface investigation is the most important phase of any civil engineering construction or development activities. The geologic conditions can be extremely complex, variable, and subject to change with time; soil test borings and in-situ tests are employed to obtain subsoil information. Resistivity Imaging (RI) is a non-destructive, fast and cost-effective method of site investigation and soil characterization. Site Investigation using Resistivity Imaging aims to summarize pertinent details of RI in site investigation for geotechnical and geo-environmental applications. It aims to bridge the gap that currently exists between the geotechnical/geo-environmental and geophysical engineering community. The geotechnical and geo-environmental engineers will be able to use annd understand geophysical data and utilize the information for their design. Features: First comprehensive handbook aimed at engineers that summarises pertinent details of Resitivity Imaging (RI) in site investigation for geotechnical and geo-environmental applications. for geotechnical and geoenvironmental engineers, making it possible to interpret geophysical data and utilize the information for their design. explanining the advantages of RI over conventional site investigations: continuous image, large coverage, low cost, quick and easy data processing. It will be a comprehensive handbook for the application of RI in geotechnical and geo-environmental site investigations.

The Restoration of Borobudur

The Restoration of Borobudur
Author: Unesco
Publisher:
Total Pages: 296
Release: 2005
Genre: Business & Economics
ISBN:

This publication traces the history and restoration of Chandi Borobudur, a Buddhist temple built over 1,000 years ago on the island of Java, Indonesia which was successfully restored during 1973-1983 and listed as a World Heritage Site in 1991. It covers the various aspects of the process, including the long and painstaking task of logging the position of the stones, the studies that revealed the underlying sources of decay, and the important archaeological finds that provided clues to the temple's spiritual past; and includes many of the original drawings and photographs taken from the restoration project archives.

A Century of Excellence in Measurements, Standards, and Technology

A Century of Excellence in Measurements, Standards, and Technology
Author: David R. Lide
Publisher: CRC Press
Total Pages: 402
Release: 2001-10-30
Genre: Science
ISBN: 9780849312472

Established by Congress in 1901, the National Bureau of Standards (NBS), now the National Institute of Standards and Technology (NIST), has a long and distinguished history as the custodian and disseminator of the United States' standards of physical measurement. Having reached its centennial anniversary, the NBS/NIST reflects on and celebrates its first century with this book describing some of its seminal contributions to science and technology. Within these pages are 102 vignettes that describe some of the Institute's classic publications. Each vignette relates the context in which the publication appeared, its impact on science, technology, and the general public, and brief details about the lives and work of the authors. The groundbreaking works depicted include: A breakthrough paper on laser-cooling of atoms below the Doppler limit, which led to the award of the 1997 Nobel Prize for Physics to William D. Phillips The official report on the development of the radio proximity fuse, one of the most important new weapons of World War II The 1932 paper reporting the discovery of deuterium in experiments that led to Harold Urey's1934 Nobel Prize for Chemistry A review of the development of the SEAC, the first digital computer to employ stored programs and the first to process images in digital form The first paper demonstrating that parity is not conserved in nuclear physics, a result that shattered a fundamental concept of theoretical physics and led to a Nobel Prize for T. D. Lee and C. Y. Yang "Observation of Bose-Einstein Condensation in a Dilute Atomic Vapor," a 1995 paper that has already opened vast new areas of research A landmark contribution to the field of protein crystallography by Wlodawer and coworkers on the use of joint x-ray and neutron diffraction to determine the structure of proteins

Handbook of Agricultural Geophysics

Handbook of Agricultural Geophysics
Author: Barry Allred
Publisher: CRC Press
Total Pages: 434
Release: 2008-06-10
Genre: Science
ISBN: 142001935X

Precision farming, site infrastructure assessment, hydrologic monitoring, and environmental investigations- these are just a few current and potential uses of near-surface geophysical methods in agriculture. Responding to the growing demand for this technology, the Handbook of Agricultural Geophysics supplies a clear, concise overview of nea

Encyclopedic Dictionary of Polymers

Encyclopedic Dictionary of Polymers
Author: Jan W. Gooch
Publisher: Springer Science & Business Media
Total Pages: 1048
Release: 2010-11-08
Genre: Science
ISBN: 1441962468

This reference, in its second edition, contains more than 7,500 polymeric material terms, including the names of chemicals, processes, formulae, and analytical methods that are used frequently in the polymer and engineering fields. In view of the evolving partnership between physical and life sciences, this title includes an appendix of biochemical and microbiological terms (thus offering previously unpublished material, distinct from all competitors.) Each succinct entry offers a broadly accessible definition as well as cross-references to related terms. Where appropriate to enhance clarity further, the volume's definitions may also offer equations, chemical structures, and other figures. The new interactive software facilitates easy access to a large database of chemical structures (2D/3D-view), audio files for pronunciation, polymer science equations and many more.

Extra High Voltage AC Transmission Engineering

Extra High Voltage AC Transmission Engineering
Author: Rakosh Das Begamudre
Publisher: New Academic Science Limited
Total Pages: 0
Release: 2011
Genre: Electric power distribution
ISBN: 9781906574741

Presented in a lucid style with easy-to-understand methodology Review Questions, Problems with Answers are given The material has been tried out for advanced undergraduate and postgraduate courses at reputed institutions.