scholarly journals Stratigraphic profiling, slip surface detection, and assessment of remolding in sensitive clay landslides using the CPT

2021 ◽  
Author(s):  
Joshua Potvin ◽  
David Woeller ◽  
James Sharp ◽  
W. Andy Take
Keyword(s):  
Pore Pressure ◽  
Slip Surface ◽  
Progressive Failure ◽  
Cone Penetration ◽  
Cone Penetration Testing ◽  
Tip Resistance ◽  
Sensitive Clay ◽  
Pore Pressure Response ◽  
Soil Behaviour ◽  
Intact Soil

A multi-year cone penetration testing program was initiated at a landslide subject to episodic retrogression in Mud Creek, Ottawa, to assess whether a hand-operated mobile CPT could yield new insights into the current degree of remoulding under progressive failure in metastable areas of a landslide where conventional tracked rigs are unable to gain access. The mobile CPT rig permitted tests to be performed through the entire thickness of the Champlain Sea deposit at a penetration rate of 0.5 cm/s, with similar results to tests performed at the standard 2 cm/s. Measurements of pore pressure varied considerably with cone size, with the magnitude of pore pressure response decreasing with cone size. The elevation of the slip surface was identified in the tip resistance as the point of transition between the remolded soil above the slip surface and the intact soil below the slip surface, whereas a further 0.5 m of penetration was required to elevate pore pressures to values indicative of the intact soil behaviour. In-situ measurements of shear strength of corresponding layers between the intact and remolded profiles to be compared indicating that the soil above the slip surface had remolded to 50% of its fully remolded strength.

Interpretation of cone penetration tests. Part I: Sand

1983 ◽  
Vol 20 (4) ◽  
pp. 718-733 ◽  
Author(s):  
P. K. Robertson ◽  
R. G. Campanella
Keyword(s):  
Shear Strength ◽  
Pore Pressure ◽  
Cone Penetration Test ◽  
Deformation Characteristics ◽  
Penetration Test ◽  
Cone Penetration ◽  
Stress History ◽  
Penetration Testing ◽  
Cone Penetration Testing ◽  
Recent Developments

Significant advances have been made in recent years in research, development, interpretation, and application of cone penetration testing. The addition of pore pressure measurements during cone penetration testing has added a new dimension to the interpretation of geotechnical parameters.The cone penetration test induces complex changes in stresses and strains around the cone tip. No one has yet developed a comprehensive theoretical solution to this problem. Hence, the cone penetration test provides indices which can be correlated to soil behaviour. Therefore, the interpretation of cone penetration data is made with empirical correlations to obtain required geotechnical parameters.This paper discusses the significant recent developments in cone penetration testing and presents a summarized work guide for practicing engineers for interpretation for soil classification, and parameters for drained conditions during the test such as relative density, drained shear strength, and deformation characteristics of sand. Factors that influence the interpretation are discussed and guidelines provided. The companion paper, Part II: Clay, considers undrained conditions during the test and summarizes recent developments to interpret parameters for clay soils, such as undrained shear strength, deformation characteristics of clay, stress history, consolidation characteristics, permeability, and pore pressure. The advantages and use of the piezometer cone are discussed as a separate topic in Part II: Clay. The authors' personal experiences and current recommendations are included. Keywords: static cone penetration testing, in situ, interpretation, shear strength, modulus, density, stress history, pore pressures.

Performance of a test embankment constructed on an organic clayey silt deposit

2001 ◽  
Vol 38 (6) ◽  
pp. 1283-1296 ◽  
Author(s):  
R Kerry Rowe ◽  
C T Gnanendran ◽  
A J Valsangkar ◽  
A O Landva
Keyword(s):  
Pore Pressure ◽  
Progressive Failure ◽  
Limit Equilibrium ◽  
Pressure Response ◽  
Equilibrium Analysis ◽  
Classical Type ◽  
3D Analysis ◽  
Clayey Silt ◽  
Pore Pressure Response ◽  
Test Embankment

The instrumentation, construction, and field performance of a full-scale test embankment constructed on a soft compressible organic clayey silt is described. The construction sequence, the observed vertical and horizontal displacements, and the pore pressure response are presented. The embankment behaved elastically up to a thickness of about 3.65 m. The settlement and heave responses suggested that the embankment approached failure at a thickness of about 6.1 m and a corresponding net height of 5.4 m. The failure was gradual and of a viscoplastic type, and no classical-type abrupt failure was encountered during the construction of this embankment. The height to which the embankment could be constructed was lower than the 7–11.4 m range expected from conventional two-dimensional (2D) limit equilibrium analysis based on vane strength data. This, coupled with the pore pressure response, suggests that a combination of progressive failure and the influence of the adjacent reinforced section constructed to failure may have been significant factors affecting the performance of this embankment. Thus, the data reported in this paper can be used as a test case for developing three- dimensional (3D) analysis methods wherein the constitutive model can be truly tested for 3D conditions involving the interaction between embankment sections that are constructed under different conditions.Key words: embankment, field behaviour, stability, deformations, pore pressures.

Continuous-interval shear wave velocity profiling by auto-source and seismic piezocone tests

2013 ◽  
Vol 50 (4) ◽  
pp. 382-390 ◽  
Author(s):  
Taeseo Ku ◽  
Paul W. Mayne ◽  
Ethan Cargill
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Test Site ◽  
Cone Penetration ◽  
Cone Penetration Testing ◽  
Large Numbers ◽  
Tip Resistance ◽  
A Site ◽  
Exploratory Procedure

A new exploratory procedure for collecting continuous shear wave velocity measurements via cone penetration testing using a special autoseis source is presented whereby wavelets can be generated and recorded every 1 to 10 s. The continuous-interval seismic piezocone test (CiSCPTu) offers a fast, productive, and reliable means to expedite the collection of downhole shear wave velocity profiles, as well as additional readings on cone tip resistance, sleeve friction, and penetration porewater pressures with depth. A site in Windsor, Virginia, is utilized for illustrating the collection of data, calibration, and post-processing issues arising from large numbers of wavelets that require filtering, windowing, and selection in both time and frequency domain analyses. At the test site, the geology consists of shallow Holocene deposits of clays and sands to 8 m that are underlain by much stiffer calcareous sandy marine clay soils of Miocene age, which extend beyond the termination depths of the soundings at 30 m.

scholarly journals Microstructural study of deformation zones during cone penetration in silt at variable penetration rates

2015 ◽  
Vol 52 (12) ◽  
pp. 2088-2098 ◽  
Author(s):  
P. Paniagua ◽  
J. Fonseca ◽  
A.S. Gylland ◽  
S. Nordal
Keyword(s):  
Pore Pressure ◽  
Penetration Rate ◽  
Test Results ◽  
Cone Penetration ◽  
Thin Sections ◽  
Soil Microstructure ◽  
Cone Penetration Testing ◽  
Backscattered Electron ◽  
Processing Techniques ◽  
Particle Orientations

During conventional cone penetration testing in silt, the soil will normally be partially drained. If the penetration rate varies, time for drainage is altered and therefore the measured cone resistance and pore pressure will change. This paper studies the change in soil microstructure around the probe during cone penetration carried out at different penetration rates to investigate the failure mechanism and the processes controlling drainage in silt. Backscattered electron images of polished thin sections prepared from frozen samples at the end of penetration were used. Making use of advanced image-processing techniques, the statistical distribution of particle orientations and the local porosity were investigated for zones around the cone tip and shaft. The spatial distribution of the measured microscale parameters in the region near the probe indicates that the soil deformation during a piezometric cone penetration test (CPTU) in silt leads to the formation of both contractive and dilative zones. The macro response of the material, presented by the pore pressure and cone penetration resistance measured during the test, results from the competition between these zones during penetration, which is shown to be dependent on the penetration rate.

The undrained equilibrium behaviour of gassy sediments

1984 ◽  
Vol 21 (3) ◽  
pp. 439-448 ◽  
Author(s):  
J. C. Sobkowicz ◽  
N. R. Morgenstern
Keyword(s):  
Pore Pressure ◽  
Oil Sands ◽  
Predictive Accuracy ◽  
Gulf Coast ◽  
Saturation Pressure ◽  
Deep Ocean ◽  
Model Parameters ◽  
Pore Pressure Response ◽  
Soil Behaviour

Gassy soils are defined as those soils which contain a relatively large amount of gas dissolved in the pore fluid. Examples include the Alberta Oil Sands, marine sediments from deep ocean locations, geopressure reservoirs along the Gulf Coast, and other naturally occurring, gas-charged reservoirs.The equilibrium behaviour during unloading with undrained boundary conditions is examined. Contrary to conventional experience with soils containing only a small amount of gas, gassy soils exhibit an equilibrium pore pressure response close to zero. Effective stress, and hence strength, decrease commensurately with total stress at the soil boundary.Laboratory observations of gassy soil behaviour are presented, which confirm the predictive accuracy of the theoretical model. Parameters important to the determination of gassy soil behaviour include the in situ state of stress (σ0 and u0), the liquid/gas saturation pressure (ul/g), the gas solubility (H), saturation (S), and the soil and liquid compressibilities (βT and βL). Key words: undrained, pore pressure, compressibility, gas, shear strength, unloading, laboratory, ex-solution.

Cone penetration testing in deltaic soils

1983 ◽  
Vol 20 (1) ◽  
pp. 23-35 ◽  
Author(s):  
R. G. Campanella ◽  
P. K. Robertson ◽  
D. Gillespie
Keyword(s):  
Pore Pressure ◽  
Test Site ◽  
Pressure Measurements ◽  
Test Results ◽  
Cone Penetration ◽  
In Situ Tests ◽  
Penetration Testing ◽  
Cone Penetration Testing ◽  
Laboratory Test Results

A multichannel electric cone penetrometer was used to perform a variety of in situ tests in saturated deltaic deposits.Factors affecting the tip bearing, friction sleeve stress, and pore-water pressures and their interpretation are studied and discussed. Pore pressure measurements were essential to evaluate the in situ test results. The effect of rate of penetration is discussed and the concept of effective bearing introduced as an attempt to interpret cone bearing in undrained or partially drained soil. Field values of consolidation characteristics from pore pressure decay are compared with traditional laboratory consolidation test results on undisturbed samples.The advantages of continuous electric cone logging to evaluate soil stratigraphy are demonstrated. Field and laboratory test results are presented from a test site where stabilization was used to reduce liquefaction potential of hydraulically placed sand and silt. The importance of pore pressure measurements is demonstrated along with examples and recommendations for the location of the porous element.Keywords: static cone penetration testing, in situ testing, pore pressures, consolidation, stratigraphy, liquefaction.

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.

scholarly journals Cone penetration testing (CPT) in Antarctic firn: an introduction to interpretation

2014 ◽  
Vol 60 (219) ◽  
pp. 83-93 ◽  
Author(s):  
Adrian McCallum
Keyword(s):  
Penetration Rate ◽  
Physical Parameters ◽  
Snow Density ◽  
Cone Penetration ◽  
Penetration Testing ◽  
Size And Shape ◽  
Cone Penetration Testing ◽  
Cone Tip Resistance ◽  
Tip Resistance

AbstractCommercial cone penetration testing (CPT) equipment was adapted to allow penetrative testing in hard polar firn to depths of 10 m. The apparatus is hydraulically driven, rate-controllable and able to penetrate firn with a resistance of 10 MPa. It can be mounted on many types of typical polar vehicles, requiring connection to only hydraulics and 12 V electricity. Data recorded include both cone tip resistance and sleeve friction, a parameter not previously examined through such testing. This paper describes the development and calibration of the equipment and examines factors including snow density, penetration rate and cone size and shape that are shown to affect CPT interpretation. CPT can be used efficiently in polar environments to potentially provide estimates of physical parameters in hard firn to substantial depth.

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