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.

Thin-layer effects on the CPT qc measurement

2005 ◽  
Vol 42 (5) ◽  
pp. 1302-1317 ◽  
Author(s):  
M M Ahmadi ◽  
P K Robertson
Keyword(s):  
Correction Factor ◽  
Soft Clay ◽  
Soil Layer ◽  
Cone Penetration ◽  
Dense Sand ◽  
Layer Interface ◽  
Cone Tip Resistance ◽  
Tip Resistance ◽  
Resistance Modeling ◽  
Good Agreement

A numerical analysis is presented to model the cone penetration test (CPT) tip resistance in layered soil. Analyses are performed for two-layer soils composed of either sands with different relative densities or different materials (sand and clay). Parametric numerical modeling is used to determine the distance that a cone senses a new upcoming soil layer interface or a layer interface behind. Analyses are also carried out for a thin sand layer embedded in soft clay. It is seen that the full tip resistance may not be reached in thin stiff layers. This is especially true for penetration in thin dense sand layers interbedded in softer clay. A correction factor is suggested to correct the cone tip resistance in thin sand layers. The higher the stiffness and the thinner the layer, the larger the correction factor. The numerical results obtained in this paper are in good agreement with experimental observations. Some limitations of a previously proposed correction factor are discussed.Key words: cone tip resistance, modeling, sand, clay, interface influence distance, layering.

Multifunctional Piezocone Penetration Testing in Geotechnical Practice

2011 ◽  
Vol 90-93 ◽  
pp. 250-254
Author(s):  
Yan Yong An ◽  
Bao Tian Wang
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Sensor Technology ◽  
Soil Parameters ◽  
Cone Penetration ◽  
Empirical Formulas ◽  
Test Technique ◽  
Penetration Testing ◽  
Porewater Pressure

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 advanced CPTU equipment, soil types were classified. As CPTU has the function of porewater pressure test, the value of porewater pressure varies a lot when the soil changes, which is shown clearly in the CPTU feature map. So it can be easier to judge soil boundaries and its result is in good agreement with the borehole. Multi-function CPTU system is equip with SCPTU module, which enable to measure shear wave velocity of the soil easily. To meet the needs of conventional CPT equipment, the relationships between shear wave velocity measured by SCPTU and other CPT indexes were analyzed; then, two empirical formulas which suitable for kinds of soils are proved more consistent with the measured results, so it is a good method to estimate shear wave velocity without seismic wave test. With a view to get greater economic and technical benefits, more cone penetration testing experience in different regions should be accumulated for geotechnical engineering investigation and design.

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.

Calibration of a Miniature Cone Penetrometer for Highway Applications

1998 ◽  
Vol 1614 (1) ◽  
pp. 8-14 ◽  
Author(s):  
Pradeep U. Kurup ◽  
Mehmet T. Tumay
Keyword(s):  
Ground Improvement ◽  
Cone Penetration Test ◽  
Test System ◽  
Soil Parameters ◽  
Cone Penetrometer ◽  
Penetration Test ◽  
Cone Penetration ◽  
Tip Resistance ◽  
In Situ Investigation

The electronic cone penetrometer is an important in situ investigation tool of choice for site characterization. Application of this proven concept of the cone penetration test (CPT) to highway design and construction control by miniaturization is described. A miniature cone penetrometer with a projected cone area of 2 cm2 has been developed and implemented in a continuous intrusion miniature cone penetration test system (CIMCPT). This device may be used for rapid, accurate, and economical characterization of sites and to determine engineering soil parameters needed in the design of pavements, embankments, and earth structures. The miniature cone penetration test (MCPT) gives finer details than the standard 10-cm2 cross-sectional area reference cone penetrometer. This makes the MCPT attractive for subgrade characterization, quality-control assessment, compaction control of embankments, and assessment of ground improvement effectiveness for transportation infrastructure. In situ calibration of the CIMCPT system was conducted at a highway embankment site in Baton Rouge, Louisiana. MCPT penetration profiles were compared with those obtained by using the standard cone penetrometer at the same site. The tip resistance of the MCPT was 10 percent higher than that of the reference CPT. The sleeve friction and friction ratio of the reference CPT were higher than that of the MCPT by 12 and 23 percent, respectively. Calibration was also performed to determine empirical cone factors required for estimating undrained shear strength from MCPT data.

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.

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.

Cone Penetration Test Study of Ultra Soft Soil after Vacuum Preloading

2014 ◽  
Vol 580-583 ◽  
pp. 585-588
Author(s):  
Jiong Qi Yu ◽  
Hong Wen Li ◽  
Wen Shuang Wang
Keyword(s):  
Surface Layer ◽  
Soft Soil ◽  
Research Work ◽  
Cone Penetration Test ◽  
Penetration Test ◽  
Cone Penetration ◽  
Vacuum Preloading ◽  
Hydraulic Fill ◽  
Cone Tip Resistance ◽  
Tip Resistance

No sand cushion vacuum preloading method is one of the construction technology for treating the ultra soft soil formed with hydraulic fill at present. The practice is ahead of the scientific research work, as the effect detection technology of the surface-layer improvement is still in the stage of exploration. In this paper, the cone penetration test (CPT) is used to detect the effect of the surface-layer improvement of the ultra soft soil based on one case in Zhejiang province in China. The result shows that the cone tip resistance is at the range of 0.08 ~ 0.40MPa and the thickness varies about 1.5 to 2.2 m of the treated ultra soft soil. The cone tip resistance along the depth has two kinds of curve shape and four zones.

scholarly journals Study of mining tailings geotechnical parameters obtained from SCPTu tests carried on dry and saturated layers

2021 ◽  
Vol 337 ◽  
pp. 04010
Author(s):  
Helena P. Nierwinski ◽  
Marcelo Heidemann ◽  
Laura A. Lavalle ◽  
Bruna Sell
Keyword(s):  
Laboratory Tests ◽  
Cone Penetration Test ◽  
Test Results ◽  
Penetration Test ◽  
Soil Behavior ◽  
Cone Penetration ◽  
Geotechnical Parameters ◽  
Saturated Layer ◽  
Laboratory Test Results

The correct interpretation of in situ and laboratory test results is an important step in the design of mining tailing containment structures. This study aims to analyze the Seismic Cone Penetration Test (SCPTu) results obtained into a mining tailing reservoir composed of two material layers: a thick-dry and a tick-saturated. It is possible to observe that in a same tailing reservoir, the CPTu test interpretation can lead to a classification of each layer as a different soil with specific behavior and properties. This condition demonstrates that tailings with intermediate permeability (10-5 m/s < k < 10-8 m/s) may present partial drainage conditions during a standard cone penetration test (CPTu) (v=20 mm/s), if saturated conditions are verified. The effects of partial drainage can affect test results, and can induce to errors in the prediction of soil behavior and geotechnical parameters. To evaluate the possible effects of partial drainage, in situ test results were compared to laboratory tests results. It was possible to verify that estimated behavior of dry layers, obtained from in situ tests results, present more similarity to the results from laboratory tests. Probably, the partial drainage effects verified through the interpretation of dissipation tests, distorted the estimated behavior of the saturated layer material.

scholarly journals Effects of sampling disturbance in geotechnical design

2019 ◽  
Vol 56 (2) ◽  
pp. 275-289 ◽  
Author(s):  
Guan Tor Lim ◽  
Jubert Pineda ◽  
Nathalie Boukpeti ◽  
J. Antonio H. Carraro ◽  
Andy Fourie
Keyword(s):  
Soil Mechanics ◽  
Soft Clay ◽  
Excess Pore Pressure ◽  
Soil Parameters ◽  
Test Results ◽  
Sample Quality ◽  
Laboratory Test Results ◽  
Geotechnical Design ◽  
Pore Pressure Response ◽  
Shallow Footing

This paper describes an experimental study of the effects of sampling disturbance in an Australian natural soft clay and the consequences of different sample quality on the representativeness of soil parameters used in geotechnical designs. The paper is divided into three sections. Laboratory test results obtained from specimens retrieved using three different tube samplers as well as the Sherbrooke (block) sampler are first described. Then, the sample quality assessment, using available indices proposed for soft soils, is presented. It is shown that sample quality varies with the stress paths and boundary conditions applied in laboratory tests. Finally, mechanical soil properties derived from specimens retrieved using the different samplers are used in the prediction of two classical problems in soil mechanics: the settlement and excess pore pressure response underneath an embankment as well as the settlement and bearing capacity of a shallow footing. These two examples are used here to highlight the consequences of poor sampling in practice.

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