Detection of smear zone using micro-cone and electrical resistance probe

2009 ◽  
Vol 46 (6) ◽  
pp. 719-726 ◽  
Author(s):  
Dong-Hyun Shin ◽  
Changho Lee ◽  
Jong-Sub Lee ◽  
Woojin Lee
Keyword(s):  
Electrical Resistivity ◽  
Electrical Resistance ◽  
Large Scale ◽  
Outer Boundary ◽  
Soil Disturbance ◽  
Cone Penetrometer ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Prefabricated Vertical Drain ◽  
Penetration Tests

The installation of a prefabricated vertical drain (PVD) using a mandrel results in soil disturbance adjacent to the PVD, which is known as the smear zone. The smear zone is investigated by a series of radial penetration tests including a micro-cone penetrometer and an electrical resistance probe in the clay specimen prepared in a large-scale chamber. The 5 mm diameter micro-cone penetrometer and the 2.1 mm diameter electrical resistance probe produce continuous soil strength and electrical resistivity profiles around the PVD. Almost-constant values of the cone tip resistance and electrical resistivity are measured within the undisturbed zone. The outer boundary of the smear zone is clearly defined by the locations where the deviations of the measured cone tip resistance and electrical resistivity from the constant values are observed. Significant changes in both measurements are observed in the smear zone with remarkably consistent patterns. The smear zone induced by the PVD installation using a rectangular mandrel has an elliptical shape and extends to approximately 3.2∼3.4 times the half-length of the mandrel and 5.3∼5.4 times the half-width of the mandrel.

Comparison of Measured and Back Estimated Cone Penetration Resistance of Sand

2008 ◽  
Author(s):  
Meen-Wah Gui ◽  
Dong-Sheng Jeng
Keyword(s):  
Penetration Resistance ◽  
Cavity Expansion ◽  
Cone Penetration ◽  
Cone Penetration Tests ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Cone Penetration Resistance ◽  
Expansion Theory ◽  
Cavity Expansion Theory ◽  
Penetration Tests

The application of cavity expansion theory in the back estimation of cone penetration tests conducted in calibration chambers has been carried out by many researchers. However, the theory is seldom employed by centrifuge modelers. Based on the work of spherical cavity expansion of previous researchers, this study proposed an analytical solution that incorporates the effects of cone geometry and surface roughness and the effect of compressibility to estimate the cone tip resistance. The calculated results are compared with the measured cone penetration resistance of four cone penetration tests performed in the centrifuge. The cone penetration tests were conducted in granular soil specimens having relative densities ranging between 54% and 89%. The comparison demonstrates the capacity of the cavity expansion theory in the prediction of the centrifuge cone penetration resistance.

Influence of placement method on the cone penetration resistance of hydraulically placed sand fills

2001 ◽  
Vol 38 (3) ◽  
pp. 592-607 ◽  
Author(s):  
K M Lee
Keyword(s):  
Cone Penetration ◽  
Density Profiles ◽  
Hydraulic Fill ◽  
Dense Sand ◽  
Cone Penetration Tests ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Wide Range ◽  
Penetration Tests

The reclamation for the new airport at Chek Lap Kok in Hong Kong included the placement of a substantial volume of sand fill by various hydraulic placement techniques, which resulted in a wide range of as-placed densities of the sand fill. This paper described the use of cone penetration tests (CPT) on the evaluation of the possible ranges of density achievable by various hydraulic placement methods adopted in the construction of the new airport. The results of the CPT indicated that the placement technique is one of the most important factors in controlling the as-placed density of hydraulically placed sand fill. There is a marked contrast in cone tip resistance (and the associated relative density) profiles for the sand fills formed by subaerial and subaqueous placement methods, in which the cone tip resistance of the sand fill formed by subaerial placement is substantially higher than that of the sand fill formed by subaequeous placement. The results confirm that dense sand fill cannot be formed by subaqueous placement methods. The weakest zone is generally located just beneath the water level where fill is placed by subaqueous discharge.Key words: sand, hydraulic fill, cone penetration test, calibration chamber test, in situ density.

Observations on the development of pore-water stresses during piezocone penetration in clays

1990 ◽  
Vol 27 (4) ◽  
pp. 418-428 ◽  
Author(s):  
Paul W. Mayne ◽  
Fred H. Kulhawy ◽  
J. Neil Kay
Keyword(s):  
Water Stress ◽  
Pore Water ◽  
Field Tests ◽  
In Situ Tests ◽  
Stress Effects ◽  
Cone Tip Resistance ◽  
Clay Deposits ◽  
Tip Resistance ◽  
Porous Element ◽  
Penetration Tests

Piezocone data from 83 clay sites are reviewed to investigate first-order trends between measured penetration pore-water stresses (ut and ubt) and corrected cone-tip resistance (qT). It is shown that the presence of fissures in clay deposits and of fissured crusts significantly affects the pore water stress response. Commercially available piezocones primarily favor the location of the porous element either (1) on the cone tip or face (ut) or (2) just behind the tip (ubt). The former (ut) provides optimal profiling while the latter (ubt) is required for correcting measured cone-tip resistances for pore-water stress effects acting on unequal areas of the cone. The available data indicate that qT predominantly reflects penetration pore-water stresses (ut) with measured ratios of ut/qT on the cone face averaging in the order of 0.73 for most intact clays, 0.64 specifically for Leda clays, and 0.46 for fissured clays. Behind the cone tip, the ratio of ubt/qT averages about 0.53 for intact clays, 0.58 specifically for Leda clays, and near zero or slightly negative for heavily overconsolidated fissured clays. Key words: clays, cone penetrometers, field tests, fissuring, in situ tests, penetration tests, piezocones, pore-water stresses.

scholarly journals A microelectromechanical system digital 3C array seismic cone penetrometer

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. WA99-WA107 ◽  
Author(s):  
Ranajit Ghose
Keyword(s):  
Shear Wave ◽  
High Frequency ◽  
Seismic Velocity ◽  
Seismic Array ◽  
Seismic Sources ◽  
Cone Penetrometer ◽  
Microelectromechanical System ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Seismic Cone Penetrometer

A digital 3C array seismic cone penetrometer has been developed for multidisciplinary geophysical and geotechnical applications. Seven digital triaxial microelectromechanical system accelerometers are installed at 0.25-m intervals to make a 1.5-m-long downhole seismic array. The accelerometers have a flat response up to 2 kHz. The seismic array is attached to a class 1 digital seismic cone, which measures cone tip resistance, sleeve friction, pore-pressure, and inclination. The downhole 3C array can be used together with impulsive seismic sources and/or high-frequency vibrators that are suitable for high-resolution shallow applications. Results from two field experiments showed that a good data quality, including a constant source function within an array, and a dense depth-sampling allowed robust estimation of seismic velocity profiles in the shallow subsoil. Using horizontal and vertical seismic sources, downhole 9C seismic array data can be easily acquired. The quality of the shear-wave data is much superior when the surface seismic source is a controlled, high-frequency vibrator in stead of a traditional sledge hammer. A remarkable correlation in depth, in a fine scale, between low-strain seismic shear wave velocity and high-strain cone tip resistance could be observed. The array measurements of the full-elastic wavefield and the broad spectral bandwidth are useful in investigating frequency-dependent seismic wave propagation in the porous near-surface soil layers, which is informative of the in situ fluid-flow properties. Stable estimates of dispersive seismic velocity and attenuation can be obtained.

Effect of Stress History and Shallow Embedment on Centrifuge Cone Penetration Tests in Sand

2019 ◽  
Author(s):  
Anamitra Roy ◽  
Shiaohuey Chow ◽  
Conleth O’Loughlin ◽  
Mark Randolph
Keyword(s):  
Silica Sand ◽  
Cone Penetration ◽  
Stress History ◽  
Buried Structures ◽  
Overconsolidation Ratio ◽  
Cone Penetration Tests ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Order Of Magnitude ◽  
Penetration Tests

Abstract The paper investigates the effect of stress history and shallow embedment on centrifuge cone penetration tests in sand. A series of centrifuge cone penetration tests were performed in loose and dense silica sand at g-levels ranging between 20 and 100 with corresponding overconsolidation ratio (OCR) between 1 and 5. Based on the measured cone tip resistance (qc) profiles, improved empirical correlations have been proposed with depth factors (fD) to impart additional flexibility in accurately back predicting sand relative density (RD) at shallow embedment in normally consolidated (NC) sands. The qc - RD correlations are then extended to capture overconsolidation effects in cone tip resistance, which is broadly consistent with the changes in compressibility and in-situ lateral stresses taking place in sands with increasing OCR levels. The proposed expressions allow accurate quantification of depth corrected CPT profiles in soils of varying overconsolidation ratio, for application in the interpretation of model tests on shallow foundations and anchors and in shallowly buried structures such as pipelines. The expressions also have application for interpretation of field CPT profiles where the thickness of interbedded layers is of similar order of magnitude to the cone diameter.

Coal mining-disturbed land reclamation laws

2020 ◽  
pp. 15-26
Author(s):  
T. V. Galanina ◽  
M. I. Baumgarten ◽  
T. G. Koroleva
Keyword(s):  
Large Scale ◽  
Land Reclamation ◽  
Mining Industry ◽  
Development Program ◽  
Soil Disturbance ◽  
Open Pit ◽  
Open Pit Mining ◽  
Disturbed Land ◽  
Critical Problems ◽  
Production Output

Large-scale mining disturbs wide areas of land. The development program for the mining industry, with an expected considerable increase in production output, aggravates the problem with even vaster territories exposed to the adverse anthropogenic impact. Recovery of mining-induced ecosystems in the mineral-extracting regions becomes the top priority objective. There are many restoration mechanisms, and they should be used in integration and be highly technologically intensive as the environmental impact is many-sided. This involves pollution of water, generation of much waste and soil disturbance which is the most typical of open pit mining. Scale disturbance of land, withdrawal of farming land, land pollution and littering are critical problems to the solved in the first place. One of the way outs is highquality reclamation. This article reviews the effective rules and regulations on reclamation. The mechanism is proposed for the legal control of disturbed land reclamation on a regional and federal level. Highly technologically intensive recovery of mining-induced landscape will be backed up by the natural environment restoration strategy proposed in the Disturbed Land Reclamation Concept.

Evaluation on Features of Soft Foundation Engineering and Bearing Layer of Pile in Jiaxing City

2011 ◽  
Vol 90-93 ◽  
pp. 217-221
Author(s):  
Jin Long Zhou ◽  
Qiao Li ◽  
Wei Zhong Cai
Keyword(s):  
Soil Mass ◽  
Shallow Foundation ◽  
Silty Clay ◽  
Foundation Engineering ◽  
Foundation Soil ◽  
Cone Tip Resistance ◽  
Soft Foundation ◽  
Tip Resistance ◽  
Bearing Layer

Through the investigation into composition of major shallow foundation soil mass and the correlation of mechanical indicators in this study, the regression equation of mechanical indicators of the features of local foundation soil mass and the data of in situ testing was obtained. Based on massive quantities of exploration materials, this study analyzed engineering features, distribution status, and the feasibility of silty clay to be used as the bearing layer of the pile in Layer ④2 . The analytical results showed that the silty clay with the uniform depth of over 3.5m and the cone tip resistance in static sounding of over 400MPa could be used as bearing layer of the pile. This study could provide the reference for the accurate understanding of the engineering features of soil mass, and the design and evaluation of foundation in Jiaxing City.

Computerized Cone Penetration Test for Soil Classification

2008 ◽  
Vol 2053 (1) ◽  
pp. 47-64 ◽  
Author(s):  
Murad Y. Abu-Farsakh ◽  
Zhongjie Zhang ◽  
Mehmet Tumay ◽  
Mark Morvant
Keyword(s):  
Classification System ◽  
Soil Classification ◽  
Cone Penetration Test ◽  
Classification Systems ◽  
Fuzzy Classification ◽  
Classification Methods ◽  
Penetration Test ◽  
Cone Penetration ◽  
Cone Tip Resistance ◽  
Tip Resistance

Computerized MS-Windows Visual Basic software of a cone penetration test (CPT) for soil classification was developed as part of an extensive effort to facilitate the implementation of CPT technology in many geotechnical engineering applications. Five CPT soil engineering classification systems were implemented as a handy, user-friendly, software tool for geotechnical engineers. In the probabilistic region estimation and fuzzy classification methods, a conformal transformation is first applied to determine the profile of soil classification index (U) with depth from cone tip resistance (qc) and friction ratio (Rf). A statistical correlation was established in the probabilistic region estimation method between the U index and the compositional soil type given by the Unified Soil Classification System. Conversely, the CPT fuzzy classification emphasizes the certainty of soil behavior. The Schmertmann and Douglas and Olsen methods provide soil classification charts based on cone tip resistance and friction ratio. However, Robertson et al. proposed a three-dimensional classification system that is presented in two charts: one chart uses corrected tip resistance (qt) and friction ratio (Rf); the other chart uses qt and pore pressure parameter (Bq) as input data. Five sites in Louisiana were selected for this study. For each site, CPT tests and the corresponding soil boring results were correlated. The soil classification results obtained using the five different CPT soil classification methods were compared.

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