Géotechnique Research Papers - Academia.edu (original) (raw)

A new approach is developed to determine the shear wave velocity in saturated soft to firm clays using measurements of the liquid limit, plastic limit, and natural water content with depth. The shear wave velocity is assessed using the site-specific variation of the natural water content with the effective mean stress. Subsequently, an iterative process is envisaged to obtain the clay stiffness and strength parameters. The at-rest earth pressure coefficient, as well as bearing capacity factor and rigidity index related to the cone penetration test, is also acquired from the analyses. Comparisons are presented between the measured clay parameters and the results of corresponding analyses in five different case studies. It is demonstrated that the presented approach can provide acceptable estimates of saturated clay stiffness and strength parameters. One of the main privileges of the presented methodology is the site-specific procedure developed based on the relationships between clay strength and stiffness parameters, rather than direct correlations. Despite of iterative processes, the presented approach can be easily implemented using a simple spreadsheet, benefiting both geotechnical researchers and practitioners.

- by roy Butterfield
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- Civil Engineering, Geotechnique, Three Dimensional, Géotechnique
- by George Mylonakis
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- Civil Engineering, Geotechnique, Géotechnique
- by Siam Yimsiri
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- Civil Engineering, Geotechnique, Géotechnique
- by Hisham Mohamad
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- Civil Engineering, Geotechnique, Géotechnique
- by Jaime Santos
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- Civil Engineering, Géotechnique
- by Rodrigo Salgado
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- Civil Engineering, Geotechnique, Bearing Capacity, Three Dimensional

In this paper numerical analysis is carried out to identify borehole log at a particular location of a site thus producing a number of parameters which are empirically related to SPT values. The Standard Penetration Test (SPT) remains the most common site investigation tool used throughout the world. Physical properties of soil is found by correlations with values of recommended standard N60, determined in SPT tests. Janjira Ap-proach road of ongoing Padma Multipurpose Bridge Project was considered for this study to collect 15 bore-hole log along 20 km stretch. Disturbed soil sample were collected up to 19.5m depth in every 1.5m interval to perform Sieve-analysis test. Spreadsheet was used to input of over 600 data including SPT-N values, Percent Sand & Percent Fines at depths, Reduce Level & Ground Water Table at different Chainage locations. By us-ing all these data- a mathematical model was developed in MATLAB, a high-level language and interactive environment for numerical compu...

- by Debojit Sarker
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- Civil Engineering, Geology, Earthquake Engineering, Geotechnical Engineering
- by Jian Chu
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- Civil Engineering, Geotechnique, Géotechnique
- by Leon Van Paassen
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- Civil Engineering, Géotechnique

O’Kelly, B. C. (2022) Discussion of “Advancement in estimation of undrained shear strength through fall cone tests” by Abhishek Ghosh Dastider, Santiram Chatterjee, and Prasenjit Basu. Journal of Geotechnical and Geoenvironmental... more

- by p a
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- Civil Engineering, Geotechnique, Numerical Model, Géotechnique
- by Jian-Hua Yin
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- Civil Engineering, Geotechnique, Géotechnique
- by Daniela Boldini and +1
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- Civil Engineering, Géotechnique

Ce document montre comment est faite l'étude complète d'une fondation en commençant par une présentation générale des différents types de fondations qui existent, puis un exemple de justification de dimensionnement est fait à l'aide des... more

- by Séverin Ovono
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- Géotechnique
- by Antonio Gens and +3
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- Civil Engineering, Geotechnique, Nuclear Waste Disposal, Géotechnique
- by Antonio Gens and +1
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- Civil Engineering, Geotechnique, Constitutive model, Critical State

Soil classification systems represent powerful tools not only to facilitate soil identification, but also to predict its possible behavior. While the use of arbitrary standards based on particle size distribution may be applicable to coarse-grained soils, those approaches based exclusively on textural principles are ineffective in classifying fine-grained soils, where clay content and its mineralogy dictate the general properties. In this sense, the measurement of plasticity represents a more appropriate parameter than particle size. This fact has led various authors and technical committees to develop fine-grained soil classification systems based on plasticity. However, the disparity of criteria makes it necessary to review them in order to glimpse the weaknesses and strengths of each of them. This paper includes the review of the six main existing proposals together with the possible variants arising from them: Casagrande (1947)-Unified Soil Classification System (USCS), American Association of State Highway and Transportation Officials (AASHTO), Federal Aviation Agency (FAA), Saito and Miki (1975), Polidori (2003, 2007, 2009) and Moreno-Maroto and Alonso-Azcarate (2017, 2018) classification charts, which are designed on the basis of Atterberg limits. After conducting a complete and thorough examination, it is shown that although the Casagrande (1947)-USCS approach is the most widely known, of all the proposals examined, only that of Moreno-Maroto and Alonso-Azcarate (2017, 2018) is based on well-founded criteria, presenting a strong predictive capacity, as well as being simple, precise and adaptable to needs.

Site investigation is essential prior to all construction activities of engineering structures for determining the suitability of the site for the construction of the proposed structure. The results from the site investigation gives us the information about the soil profile and the ground water table condition at the site. Various in-situ tests are carried out like Standard Penetration Test (SPT), Electrical Resistivity Technique (ERT), Vane Shear Test (VST), Plate Load Test (PLT), Pile Load Test, Flat Plate Dilatometer Test, Packer Test, Cone Penetration Test (CPT) and many others during the site exploration. The data and results obtained from these tests are essential in identifying the soil type, analyzing and the strength and deformation properties and parameters of soil as well as the ground water condition of the site. This paper intends to summarize the processes and various corrections that are involved in Standard Penetration Test (SPT) and its importance and implication in geotechnical analysis and site exploration. The tools and equipment in this test involved are cable percussion drilling rig, soil sampler (especially split spoon sampler), spirit level, boring machine and a hammer with few other miscellaneous. The soil sampler is pushed or penetrated into the ground by hammer of 63.5kg making it fall freely from a standard height of 750mm. The collected disturbed and undisturbed soil samples, hammer blows and energy are analyzed and interpreted to determine or more specifically to estimate the shear strength of soil, relative density and bearing strength of the soil at different depths. This test also helps in determining the aspects of soil which later can be improved by soil stabilizing or by any one or combination of various ground improvement techniques. In accordance of these interpretations, analysis and estimates, suitable foundation design and further construction work for the proposed structure are recommended.

- by Laïfa Ourkia
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- Geotechnique, Géotechnique
- by A. Mandolini
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- Civil Engineering, Forecasting, Forecast, Settlement
- by Stephan Jefferis
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- Civil Engineering, Géotechnique

This study investigates the combined efficacy of waste-tire-derived aggregate (TDA) materials and hydrated lime on the compactability, compressive strength and swelling potential of a highly expansive soil from South Australia. A total of 21 mix-designs, covering a comprehensive range of soil-TDA-lime combinations, were examined through standard Proctor compaction, unconfined compressive strength (UCS) and oedometer swell tests. The mobilized UCS exhibited a 'rise-fall' behavior, peaking at 5% TDA content and subsequently decreasing (monotonically) for higher inclusions of TDA. Increasing the TDA mean particle size (from 1.67 to 3.34 mm) also contributed positively to the UCS development. Addition of TDA to the soil/soil-lime-blends produced notable reductions in the swelling potential; the reduction was primarily governed by higher TDA contents, and, to a lesser degree, for larger TDA mean particle sizes. However, the role of TDA particle size in reducing swelling was found to be more significant than that of enhancing the UCS. As expected, lime treatment of the soil-TDA blends provided major further improvements to the UCS and swelling potential reduction; the achieved UCS improvements being positively proportional to the lime content and curing time. In view of the experimental results, soil-lime blends containing TDA to soil-lime mass ratios of up to 10% (preferably employing coarse-sandsized equivalent TDA) can be deemed as suitable choices (capable of adequately mitigating the swelling potential, while simultaneously enhancing the UCS).

- by Brendan C . O'Kelly
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- Geotechnical Engineering, Soil Mechanics, Pavement Materials, Expansive Soils

Soil stabilization using nanomaterials is an emerging research area although, to date, its investigation has mostly been laboratory-based and therefore requires extensive study for transfer to practical field applications. The present study advocates nano-calcium carbonate (NCC) material, a relatively unexplored nanomaterial additive, for stabilization of low-plasticity fine-grained soil having moderate organic content. The plasticity index, compaction, unconfined compressive strength (UCS), compressibility and permeability characteristics of the 0.2%, 0.4%, 0.6% and 0.8% NCC-treated soil, and untreated soil (as control), were determined, including investigations of the effect of up to 90-d curing on the UCS and permeability properties. In terms of UCS improvement, 0.4% NCC addition was identified as the optimum dosage, mobilizing a UCS at 90-d curing of almost twice that for the untreated soil. For treated soil, particle aggregation arising from NCC addition initially produced an increase in the permeability coefficient, but its magnitude decreased for increased curing owing to calcium silicate hydrate (CSH) gel formation, although still remaining higher compared to the untreated soil for all dosages and curing periods investigated. Compression index decreased for all NCC-treated soil investigated. SEM micrographs indicated the presence of gel patches along with particle aggregation. X-ray diffraction (XRD) results showed the presence of hydration products, such as CSH. Significant increases in UCS are initially attributed to void filling and then because of CSH gel formation with increased curing.

- by Chloé Arson and +1
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- Civil Engineering, Géotechnique

The undrained shear strength of soil is a key engineering parameter, which is often linked to liquidity index (e.g. Vardanega and Haigh 2014). This linkage depends critically on the undrained strength of soil at the liquid limit, a subject on which there has been some debate. The determination of the liquid limit is carried out using one of two general methods: ‘Casagrande cup’ or ‘fall cone’, depending on national standards. The authors have presented an interesting paper that shows (amongst other things) how fall-cone undrained shear strength values at the fall-cone liquid limit (cuFC;LL) can vary with changes in the water content at the fall-cone liquid limit (wL;FC ). Data of the undrained strength at liquid limit when this is determined by the fall cone are rare, although since this test is itself a measurement of soil strength, examination typically shows a much narrower range of values than for strengths measured at the Casagrande-cup liquid limit (wL;cup ). It is hence surprising that the work of Nagaraj et al. (2018) shows such clear trends of varying undrained strength at the fall-cone liquid limit with water content. The paper hence prompts a debate as to whether the undrained strength at the fall-cone liquid limit can be sensibly assumed as a fixed value. This discussion seeks (in the context of the published paper) to explore this question.

- by Brendan C . O'Kelly and +1
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- Soil Science, Geotechnical Engineering, Soil Mechanics, Geotechnical Investigation

In this paper, numerical analysis is carried out to identify borehole log at a particular location of
a site thus producing a number of parameters which are empirically related to SPT values. The Standard Penetration Test (SPT) remains the most common site investigation tool used throughout the world. Physical properties of soil are found by correlations with values of recommended standard N60, determined in SPT tests.
Janjira Approach road of ongoing Padma Multipurpose Bridge Project was considered for this study to collect
15 borehole log along 20 km stretch. Disturbed soil sample were collected up to 19.5m depth in every 1.5m
interval to perform Sieve-analysis test. Spreadsheet was used to input of over 600 data including SPT-N values, Percent Sand & Percent Fines at depths, Reduce Level & Ground Water Table at different Chainage locations. By using all these data- a mathematical model was developed in MATLAB, a high-level language and
interactive environment for numerical computation, visualization, and programming. Rectangular grids in
multidimensional space were created for Interpolation and/or Extrapolation for 2-D and/or 3-D gridded data
in ‘meshgrid’ format. The purposes of the study are to find vertical SPT profile & soil-profile in a particular
alignment of the site and to extract borehole log form SPT profile & soil-profile at intermittent locations of
that alignment. SPT profile is presented graphically using contour plot of matrix and soil-profile is presented
by 3-D shaded surface plots. Predicted borehole log could be useful for preliminary selection of a project site,
land use planning, zoning ordinances, pre-disaster planning, and capital investment planning. Seismic soil liquefaction was evaluated for this site in terms of the factors of safety against liquefaction (FS) along the
depths of soil profiles for different peak ground acceleration ranging 0.3g to 0.45g and earthquake magnitude
ranging 6 to 7.5 on Richter scale. Cyclic Strength Ratio (CSR) and Cyclic Resistance Ratio (CRR) was determined with 10 % probability of exceedance in 50 year using SPT-based simplified empirical procedure.
Liquefaction potential index (LPI) is evaluated at borehole locations from the obtained factors of safety (FS)
to assess the potential of liquefaction to cause damage at the surface level at the site of interest. To validate
the model, recent occurred Nepal Earthquake was taken as an example to compare the level of liquefaction
severity assessed by in-situ and predicted borehole log data.

- by Debojit Sarker
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- Civil Engineering, Geology, Earthquake Engineering, Geotechnical Engineering
- by Subhamoy Bhattacharya
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- Civil Engineering, Geotechnique, Case History, Failure Mechanism

The shear wave velocity VS is an essential parameter in various geotechnical analyses. It can be determined using laboratory testing of undisturbed samples, in-situ geophysical measurements, or by using correlations of the shear wave velocity with the common in-situ penetration tests such as the standard penetration tests (SPT) and the cone penetration test (CPT). The latter approach is often preferred by engineers for many reasons including cost optimization of the geotechnical investigations and infeasibility of undisturbed sampling in some formations such as non-cohesive soils. Accordingly, many correlations were envisaged to determine the shear wave velocity using the CPT; these correlations were developed through statistical and regression analyses of compiled CPT and shear wave velocity databases. Yet, to date, substantial discrepancies between the existing CPT correlations and the measured shear wave velocities are still revealed when the CPT correlations are compared with more recent case histories and databases. As such, there is a continuous need to update these correlations. In this study, a proposed approach is presented to define the stress-dependency parameters of the shear wave velocity in terms of the CPT measurements. Hence, enhanced CPT correlations for the shear wave velocity and the small strain modulus in both cohesionless and cohesive soils are realised. Two case studies are analysed using the proposed CPT correlation for the shear wave velocity as well as the commonly applied correlations. It is shown that the proposed CPT-VS correlation provides consistent predictions with the measured shear wave velocity; hence, it may be considered as an enhancement to the currently adopted methods.

- by Rodrigo Salgado and +2
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- Civil Engineering, Geotechnique, Géotechnique
- by Rodrigo Salgado and +1
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- Civil Engineering, Geotechnique, Géotechnique
- by Raffaele Di Laora and +1
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- Civil Engineering, Géotechnique

The ground is a natural grand system; it is composed of myriad constituents that aggregate to form several geologic and biogenic systems. These systems operate independently and interplay harmoniously via important networked structures over multiple spatial and temporal scales. This paper presents arguments and derivations couched by the authors, to first give a better understanding of these intertwined networked structures, and then to give an insight of why and how these can be imitated to develop a new generation of nature-symbiotic ground engineering techniques. The paper draws on numerous recent advances made by the authors, and others, in imitating forms (e.g. synthetic fibres that imitate plant roots), materials (e.g. living composite materials, or living soil that imitate fungi and microbes), generative processes (e.g. managed decomposition of construction rubble to mimic weathering of aragonites to calcites), and functions (e.g. recreating the self-healing, self-producing, and self-forming capacity of natural systems). Advances are reported in three categories of Materials, Models, and Methods (3Ms). A novel value-based appraisal tool is also presented, providing a means to vet the effectiveness of 3Ms as standalone units or in combinations.

- by Brendan C . O'Kelly
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- Geotechnical Engineering, Soil Mechanics, Soil Microbial Ecology, Biomimicry
- by Ennio Polidori
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- Civil Engineering, Plasticity, Clay Minerals, Classification
- by Susan Gourvenec
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- Civil Engineering, Geotechnique, Géotechnique

Hydraulic erosion is one of the main causes of failure within earth dams and embankments. Various methods are used to mitigate against such erosion, a common approach being grouting with cement, clay or chemical materials. Biogrouting using the microbial-induced carbonate precipitation technique is a relatively new, cost-effective, technically appropriate and environmentally friendly soil improvement method. Bacteria injected into the soil produce urease enzyme, which converts urea to ammonium and carbonate, causing calcite precipitation that binds soil grains together. In this study, the erodibility parameters of dense silica sand specimens treated with different injection strategies were investigated at bench scale. More effective treatment – in terms of greater and more uniform calcite precipitation over the test-specimen length, and hence greater erosion resistance – was achieved by aeration during solution injections and by incorporating a drained stage between injection cycles. With the latter, calcite precipitated as larger crystals, accumulating extensively over grain surfaces and also formed integrated in the pore voids. The best-performing treatment strategy produced a 95% reduction in erodibility and a five-fold increase in critical shear stress relative to untreated sand. These findings were confirmed by scanning electronic microscopy and calcium carbonate titration tests.

- by Alain Corfdir
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- Civil Engineering, Geotechnique, Géotechnique
- by Antonio Gens
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- Civil Engineering, Finite Element Analysis, Geotechnique, Géotechnique
- by Mazhar Iqbal Arshad
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- Civil Engineering, Géotechnique
- by alessandro flora
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- Civil Engineering, Geotechnique, Géotechnique
- by A. Josa
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- Civil Engineering, Shear Stress, Geotechnique, Stress Transfer

Recently, Spagnoli et al. (2019) investigated the relationships between the flow index (FI) − defined as the slope of the w-log 10 N plot (where w = water content and N = number of blows) obtained from the Casagrande-cup method − and the conventional soil consistency parameters, i.e., Casagrande-cup liquid limit (LL), thread-rolling plastic limit (PL), and plasticity index (PI = LL − PL). It was concluded that the FI is poorly correlated with the PL. On the contrary, the authors reported that the LL and, more importantly, the PI both exhibited relatively strong correlations with the FI. In this regard, a linear relationship in the form of PI = 6.07 × FI (with coefficient of determination (R2) = 0.91 obtained for a database of 59 soil materials) was proposed and validated by the authors, thus allowing an indirect estimation of the PI without the need for conducting the subjective thread-rolling PL test. The work under discussion attempts to further solidify an interesting concept, as originally introduced by Sridharan, Nagaraj, and Prakash (1999), from which soil plasticity is quantified in a more objective manner. Further, it would follow that the PL can be predicted having determined the LL and FI from the experimental flow curve as PL = LL − 6.07 × FI.

- by David M Cruden
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- Civil Engineering, Geotechnique, Géotechnique
- by George Mylonakis
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- Civil Engineering, Géotechnique
- by moh mohamed
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- Génie Civil, Géotechnique

Construction on peat deposits represents a major challenge for the geotechnical community. Waterlogged peat deposits have great potential for buoyancy generation. The premise of the present investigation is that this can be beneficially incorporated in foundation design practice, thereby reducing the net bearing pressure and hence resulting settlements. A novel foundation system, comprising a bamboo frame (BF) structure incorporating recycled plastic block (RPB) inclusions, is presented for supporting lightweight structures bearing on peaty ground. The buoyancy effect is produced by the lower bulk density of the foundation construction materials combined with the waterlogged condition of the peat deposit. A programme of reduced-scale 1g physical modelling was conducted to investigate the performance of BF- and BF–RPB-type footing bearing on remoulded peat with different water content and fibre content (FC) values. The mobilised undrained bearing capacity (qf) increased for lower-watercontent and higher-FC peat materials. Deeper BF footings and the inclusion of the RPBs within their cavities significantly improved the mobilised qf value. Advantages of the presented foundation system over conventional solutions for peaty ground include its simple technology, reduced earthworks in construction, reduced settlement due to the buoyancy contribution and being more sustainable and economically viable.