Statistical relationships between piezocone measurements and stress history of clays

1996 ◽  
Vol 33 (3) ◽  
pp. 488-498 ◽  
Author(s):  
B SY Chen ◽  
P W Mayne
Keyword(s):  
Cone Penetration ◽  
Stress History ◽  
Statistical Correlations ◽  
Cone Tip Resistance ◽  
Clay Deposits ◽  
Preconsolidation Pressure ◽  
Tip Resistance ◽  
History Of ◽  
Statistical Relationships ◽  
Oedometer Tests

A database containing piezocone soundings from 205 clay sites around the world has been compiled for the calibration of an analytical cone penetration model and the development of statistical correlations. Yield stresses from laboratory oedometer tests were used as reference values for determining the stress history of natural clay deposits. Both simple and multiple regression analyses were performed on these data to evaluate correlative trends. Several simplified empirical relationships were identified for use in practice with the most reliable in relating preconsolidation stress to net cone tip resistance. Key words: cone tip resistance, overconsolidation ratio (OCR), preconsolidation pressure, piezocone, statistical relationships, stress history.

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.

scholarly journals Parameterisation of the Koppejan settlement prediction model using cone penetration testing and gradient boosting

2020 ◽  
Vol 382 ◽  
pp. 443-447
Author(s):  
Kevin Duffy ◽  
Klaas Siderius ◽  
Mike Long
Keyword(s):  
Human Error ◽  
Gradient Boosting ◽  
Engineering Practice ◽  
Cone Penetration ◽  
Settlement Prediction ◽  
Fine Grained ◽  
Cone Penetration Testing ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Oedometer Tests

Abstract. This study examines how cone penetration test (CPT) parameters, such as cone tip resistance and friction sleeve resistance, can be used to assess the compressibility of fine-grained soils across the Netherlands based on a database of 286 paired CPTs and oedometer tests from across the country. This is done with the aim of refining and simplifying the parameterisation of the Koppejan consolidation coefficients, a procedure which can yield significant error and is prone to misinterpretation. It was found that there is significant potential in using gradient boosting methods to obtain a relationship between the CPT parameters and the Koppejan parameters, with further investigation required into the noise within the dataset and the acquisition of additional high-quality samples. The use of such methods will offer a means of reducing the influence of human error or misinterpretation on the prediction of settlement and provide further confidence in the use of machine learning methods in engineering practice.

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.

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.

Determining Preconsolidation Pressure of the Lakeside New District Soft Clay of Hefei Based on Casagrande Method by Matlab

2013 ◽  
Vol 291-294 ◽  
pp. 1113-1116
Author(s):  
Yan Shao ◽  
Chang Yong Li ◽  
Yuan Wei
Keyword(s):  
Soft Clay ◽  
Least Square Method ◽  
Least Square ◽  
Compression Curve ◽  
Stress History ◽  
Important Index ◽  
Preconsolidation Pressure ◽  
Quartic Polynomial ◽  
History Of ◽  
Calculation Parameter

The preconsolidation pressure is an important index to determine the stress history of soil and also a major calculation parameter for the analysis of soil stratum’s deformation in the different stress history. Casagrade method is worldwide applied to determine the preconsolidation pressure. On the basis of research on consolidation test about the lakeside new district soft clay of Hefei by high pressure consolidation apparatus, and conformed to Casagrande method, the paper adopts quartic polynomial and least square method to fit the compression curve, and the preconsolidation pressure of the lakeside new distract soft clay of Hefei is determined by matlab software. The result provides reference for the calculation of foundation settlement considering stress history.

Interpretation of overconsolidation ratio from in situ tests in Recent clay deposits in Singapore and Malaysia

1991 ◽  
Vol 28 (2) ◽  
pp. 210-225 ◽  
Author(s):  
M. F. Chang
Keyword(s):  
Site Investigation ◽  
Test Methods ◽  
In Situ Tests ◽  
Stress History ◽  
Overconsolidation Ratio ◽  
Clay Deposits ◽  
Preconsolidation Pressure ◽  
Pressure Stress ◽  
Sample Disturbance

The stress history as indicated by the profile of overconsolidation ratio (OCR) of a soil deposit is one of the most dominant factors that influence the engineering behaviour of the soil. Its assessment, which is traditionally based on the laboratory oedometer test, is not often satisfactory. The problem arises from inevitable sample disturbance and the high cost of a detailed investigation. These difficulties can be overcome by the use of in situ tests. The field vane test, the piezocone test, and the dilatometer test are three such methods that provide indirect means for the estimation of the OCR for clay deposits. A number of empirical correlations are available for this purpose. Calibration of these correlations against results of site investigation in Singapore and Malaysian marine clays reveals the usefulness of these test methods in profiling the OCR for Recent clay deposits. Key words: clay, in situ test, overconsolidation ratio, preconsolidation pressure, stress history.

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.

Experimental Research on Determining the Geotechnical Parameters with CPTU Methods

2011 ◽  
Vol 250-253 ◽  
pp. 1798-1803
Author(s):  
Yan Yong An ◽  
Bao Tian Wang
Keyword(s):  
Soft Clay ◽  
Cohesive Soil ◽  
Sensor Technology ◽  
Soil Parameters ◽  
Cone Penetration ◽  
Test Technique ◽  
Geotechnical Parameters ◽  
Cone Tip Resistance ◽  
Laboratory Test Results ◽  
Tip Resistance

Cone penetration test is a fast and efficient in-situ test technique. With the development of sensor technology and the use of new probes, such test is employed in more fields and reveals more soil parameters. Based on the advanced CPTU equipment, porewater pressure dissipation processes were measured at different depths, dissipation characteristics of the sandy soil and cohesive soil were analyzed respectively; Then, consolidation and permeability coefficients of the cohesive soil were calculated, the results are close to the laboratory test results. Undrained shear strength of soft clay were determined use theoretical and empirical methods, calculation accuracy of these methods were analyzed and the results show that the total cone tip resistance method is in good consistence with the measured values. CPTU is able to provide plenty of geotechnical parameters; therefore, more experience of regional tests should be drawn so as to produce more economic and technical benefit in the future.

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.

Evaluation of preconsolidation pressure and the overconsolidation ratio from piezocone tests of clay deposits in Quebec

2002 ◽  
Vol 39 (1) ◽  
pp. 174-192 ◽  
Author(s):  
Denis Demers ◽  
Serge Leroueil
Keyword(s):  
Mechanical Behaviour ◽  
Laboratory Tests ◽  
Local Data ◽  
Overconsolidation Ratio ◽  
Clay Deposits ◽  
Pressure Profiles ◽  
Preconsolidation Pressure ◽  
Tip Resistance ◽  
Sensitive Clay

The preconsolidation pressure and overconsolidation ratio profiles are the most important factors related to the mechanical behaviour of clay deposits. They are interpreted on the basis of a limited number of laboratory tests, but the near-continuous information provided by the piezocone can allow local data to be extrapolated to an entire site. Numerous methods have been proposed for relating piezocone data to preconsolidation pressure and the overconsolidation ratio, but their validity is still uncertain. In this paper, nine methods are compared on the basis of data collected on 31 sensitive clay sites in Quebec whose preconsolidation pressure profiles are well known. Each method is briefly presented and the most promising are identified. The simplest method, which directly relates preconsolidation pressure to net tip resistance, also appears to be the most effective.Key words: clay, preconsolidation pressure, overconsolidation ratio, piezocone, correlations.

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