Cone Pressuremeter Tests Research Articles

Stiffness parameters from cone pressuremeter tests at Changi East, Singapore

A large-scale land reclamation project was carried out in the eastern part of Singapore involving 2000 hectares of land at a foreshore location from 1991 to 2005. The land was reclaimed, by placing sand hydraulically on the seabed comprising soft marine clay. Prefabricated vertical drains with surcharge preloading and deep compaction techniques, were used to improve the soft marine clay and reclaimed sand fill. Several specialist in situ tests were conducted during the project, such as with the cone penetration test (CPT), cone pressuremeter test (CPMT), dilatometer test and self-boring pressuremeter tests. The CPMT is an in situ testing method used to measure both the soil strength and stiffness parameters. The CPMT combines the advantages of a conventional pressuremeter test and a CPT. The CPT provides a continuous profile of the soil by measuring the stress on the cone tip, the sleeve friction and the pore-water pressure. The CPMT enables the assessment of the soil strength and stiffness at selected depths. CPMT tests were conducted on both the reclaimed sand and underlying soft marine clay layers during the Changi East reclamation project.

Discrete element modelling of cavity expansion and pressuremeter test

Cavity expansion in soil or rock is an important area in theoretical geomechanics because it provides a useful and simple tool for modelling many complex geotechnical problems. This paper describes the simulation of cylindrical cavity expansion and pressuremeter testing of granular materials using the discrete element method (DEM). The Pressuremeter test is one of the most important applications of cavity expansion theory. The theory of cylindrical cavity expansion has been adapted by geotechnical researchers and engineers as the most important interpretation method for self-boring pressuremeter tests in soil and rock. It is also used to describe the soil properties of cone pressuremeter tests. To compare the DEM simulation results with continuum analysis, analytical solutions of large strain expansion of Mohr-Coulomb material are also given. For simplicity, the soil stress-strain behaviour is considered as elastic-perfectly plastic. Some biaxial test simulations using DEM are performed to obtain the basic granular material properties for obtaining cavity expansion analytical solutions based on continuum mechanics. Macro properties of the samples for various input micro parameters are presented and used to obtain the theoretical cavity expansion solutions. The comparison between the numerical simulations and analytical solutions shows good agreement. A range of pressuremeter test simulations of various initial porosities using different particle shapes were conducted. The simulations demonstrated the validity of DEM simulations of the pressuremeter test, providing micromechanical insight into the behaviour.

Evaluation of soil state from SBP and CPT: A case history

The cone pressuremeter test (CPT) is widely used to determine the in situ “state” of cohesionless soils. However, although the CPT is simple, inexpensive, and accurate the subsequent interpretation contains substantial uncertainties even with modern approaches. Self-bored pressuremeters (SBP) have the opposite attributes. Obtaining good SBP data is difficult in sands, but the subsequent evaluation can be rather precise. This paper compares estimates of the in situ state parameter, ψ, from CPT and SBP tests carried out in a uniform hydraulic fill. This case history is unusual in that (i) the fill was well controlled and uniform, (ii) comprehensive laboratory strength data exists, (iii) the CPT was calibrated for the fill in a large chamber, and (iv) good SBP data exist. These SBP and CPT tests are independently analyzed using a calibrated critical state model implemented in a large strain finite element code. The effects of ageing and fabric are considered. The resulting most probable in situ state parameters for the fill from the CPT are close to those derived from the SBP. Although not proof of accuracy (validation) of either test, since ground truth is not known, the results lend support to the adequacy of the interpretation methodology used for both. Further improvements are discussed.

The cavity expansion problem for the interpretation of cone penetration and pressuremeter tests

The cavity expansion problem for the interpretation of cone penetration and pressuremeter tests

Discussion and Closure: Analysis of Cone Pressuremeter Tests in Sands

Discussion and Closure: Analysis of Cone Pressuremeter Tests in Sands

Discussion of “Analysis of Cone Pressuremeter Tests in Sands” by H. S. Yu, F. Schnaid, and I. F. Collins

Discussion of “Analysis of Cone Pressuremeter Tests in Sands” by H. S. Yu, F. Schnaid, and I. F. Collins

Analysis of Cone Pressuremeter Tests in Sands

This paper presents an interpretation method for determining sand properties from the cone tip resistance and the pressuremeter limit pressure measured with the cone pressuremeter. The method developed here can be used to deduce the angle of internal soil friction and in-situ sand state from the ratio of measured cone tip resistance and pressuremeter limit pressure. In developing the theoretical correlations between soil strength parameters and the cone pressuremeter test results, the limit pressures of both spherical and cylindrical cavity expansions in sand are used to estimate the cone tip resistance and the pressuremeter limit pressure, respectively. The relevance of this simple interpretation method has been confirmed by the results of a large number of cone and pressuremeter tests carried out in both calibration chambers and the field.

Discussion: Measurement of the properties of sand in a calibration chamber by the cone pressuremeter test

Discussion: Measurement of the properties of sand in a calibration chamber by the cone pressuremeter test

Interpretation of shear moduli from cone pressuremeter tests in sand : G. T. Houlsby & F. Schnaid, Geotechnique, 44(1), 1994, pp 147–164

Interpretation of shear moduli from cone pressuremeter tests in sand : G. T. Houlsby & F. Schnaid, Geotechnique, 44(1), 1994, pp 147–164

Interpretation of shear moduli from cone pressuremeter tests in sand

The interpretation of the elastic shear modulus obtained from cone pressuremeter tests is examined to assess the influence of installation disturbance and other factors on the measurement of soil stiffness. In particular it is shown that the cone pressuremeter test can give reliable values of unload-reload shear modulus. The typical shape of unload-reload loops is examined, and two procedures to calculate the shear modulus are proposed. The shear moduli calculated from measurements made with strain arms and those calculated from volume change measurements are compared. A method is presented that allows the relevant stress level acting around the pressuremeter during the test to be taken into account in the interpretation of measurements of the shear modulus. The values of the moduli obtained from the cone pressuremeter are comparable with those obtained from the self-boring pressuremeter. L'article s'intéresse à l'interprétation du module de cisaillement élastique obtenu à partir d'essais de cone-pressiomètre afin d'étudier l'influence des perturbations induites lors de l'installation de l'appareil et de certains autres facteurs sur les mesures de raideur des sol. Il apparaît en particulier que l'essai cone-pressiomètre peut fournir des valeurs fiables de module de cisaillement lors de cycles chargement-déchargement. La forme typique des courbes de chargement-déchargement est examinée et deux méthodes permettant de calculer le module de cisaillement sont proposées. Les modules de cisaillement calculés à partir de mesures faites à l'aide de capteurs de déplacement sont comparés à ceux issus de measures par variation de volume. L'article présente une méthode qui permet de prendre en compte, lors de l'interprétation des mesures de module de cisaillement, la contrainte réelle agissant autour du pressiomètre pendant l'essai. Les valeurs du module obtenues à partir du cone-pressiomètre sont comparables à celles obtenues à l'aide d'un pressiomètre autoforeur.

Measurement of the properties of sand in a calibration chamber by the cone pressuremeter test Geotechnique V42, N4, Dec 1992, P587–601 : Schnaid, F; Houlsby, G T

Measurement of the properties of sand in a calibration chamber by the cone pressuremeter test Geotechnique V42, N4, Dec 1992, P587–601 : Schnaid, F; Houlsby, G T

Measurement of the properties of sand in a calibration chamber by the cone pressuremeter test

The cone pressuremeter is a new site investigation device which incorporates a pressuremeter behind a standard cone penetrometer tip. This Paper seeks to develop an understanding of the new device, and to establish a procedure to allow the test to be used to determine the engineering properties of cohe-sionless soils. A series of calibration chamber tests is described, in which three cone pressuremeter prototypes of different cross-sectional areas were used. A programme of calibration designed to examine the influence of relative density, stress level and stress ratio on the values of limit pressure obtained from the cone pressuremeter test and the cone resistance values obtained from the cone test is presented. A procedure for deducing the in situ horizontal stress, density and friction angle is described, and is used to back-analyse the test data. Le cÔne pressiomètre est un nouvel appareil de reconnaissance de sols qui incorpore un pressiomètre placè derrière un cône classique. Cet article cherche à dèvelopper notre connaissance de ce nouvel appareil et à ètablir une nouvelle procèdure peremettant à l'essai d'être utilisè pour dèterminer les propriètès mècaniques des sols sans cohèsion. Une suite d'essais faits dans une enceinte de calibration est dècrite dans laquelle 3 prototypes de cône pressiomètre de diffèrentes sections furent utilisès. On prèsente dans cet article un programme de calibration conçu pour examiner l'influence de la densitè relative, du niveau des contraintes et du rapport des contraintes sur les valeurs de pression limite obtenues à partir de l'essai au cône pressiomètre et les valeurs de rèsistance de pointe obtenues à partir de l'essai au cône. Une procèdure pour dèduire les contraintes horizontales in-situ, la densitè et l'angle de frottement interne est dècrite et est utilisèe pour l'analyse rètrospective des rèsultats des essais.

Evaluation of cone pressuremeter tests in soft cohesive soils : Campanella, R G; Howie, J A; Hers, I; Sully, J P; Robertson, P K Proc 3rd International Symposium on Pressuremeters, Oxford, 2–6 April 1990P125–135. Publ London: Thomas Telford, 1990

Evaluation of cone pressuremeter tests in soft cohesive soils : Campanella, R G; Howie, J A; Hers, I; Sully, J P; Robertson, P K Proc 3rd International Symposium on Pressuremeters, Oxford, 2–6 April 1990P125–135. Publ London: Thomas Telford, 1990

Performance and analysis of cone pressuremeter tests in sands : GeotechniqueV39, N3, Sept 1989, P433–454

Performance and analysis of cone pressuremeter tests in sands : GeotechniqueV39, N3, Sept 1989, P433–454

Performance and analysis of cone pressuremeter tests in sands

This Paper presents the results of tests performed in sand with a prototype cone pressuremeter. Values of shear modulus and friction angle of the sand are derived from the data using cavity expansion/contraction theory. These values are compared with those obtained from seismic cone penetration tests and self boring pressuremeter tests. The Paper aimsto stimulate the development of methods to evaluate and apply data obtained from testsin sands with this operationally convenient in situ test. The values of shear modulus obtained with the cone pressuremeter are compatible with those obtained from the other tests. The availability of a cone resistance profile provided by the cone pressuremeter, at the same location as the pressuremeter derived shear moduli, facilitates the production of a continuous depth profile of shear modulus based on a reliable site specific correla- tion. Available cavity expansion theory produces unrealistic values of peak friction and dilation angle from cone pressuremeter data. Available cavity contraction theory produces unrealistic values of friction and dilation angle from both cone pressuremeter and self boringpressuremeter data. Creep deformations contribute to the difficulties associated with theapplications of cavity expansion and contraction theories. However, with appropriate tes procedures the creep deformation can be identified. A standard test procedure is proposedto facilitate comparisons of data obtained from further tests in different sands. Such comparisons are needed to advance understanding of cone pressuremeter test data. L'article présente les résultats d'essais effectués dans du sable à l'aide d'un pressiométre à c^ane prototype. Des valeurs du module de cisaillement et de I'angle de frottement du sable sont déduites de ces données par l'emploi de la tMorie de l'expansion–contraction des cavités. Ces valeurs sont comparées avec celles obtenues à partir d6essais sismiques de péneration au cône et d'essais au pressiométre à autoforeur. Le but est de stimuler le développement de méthodes pour Evaluation et I'application des données obtenues à partir d'essais effectués dans le sable à I'aide de cet essai in-situ trés pratique. On en tire les conclusions suivantes: les valeurs du module de cisaillement obtenues par moyen du pressiométre à cône sontcompatibles avec celles obtenues à partir des autres essais; la production d'un profile continu de profondeur du module de cisaillement basée sur une corrélation spécifique et fiable est facilitée par la disponibiliti d'unprofil de réisstance au cône fourni par le pressiométre à cône au meme emplacement que les modules de cisaillement dérivés du pressiométre; la théorie actuelle de I'expansion des cavités donne des valeurs peu rélles du frottement et de l'angle de dilatation 1 partier desdonées du pressiométre à cône; la théorie actuelle de là contraction des cavités donne des valeurs peu réelleses du frottement et de I'angle de dilatation à partir des données du pressiométre à cône et du pressiométre à autoforeur; les défor-mations par fluage augmentent les difflcultés lorsque les théories de l'expansion et de la contraction des cavités sont employées, bien qu'il soit possible de définir la déformation par fluage à I'aide de procédures d'essais appropriées. L'article propose une procédure normale d'essai pour faciliter la comparaison des données obtenues à partir d'autres essais effectués dans des sables différents. De telles comparaisons sont n&essaires pour améiorer la comprithension des données des essais de pressiométre à cône.

Analysis of the cone pressuremeter test in clay

Analysis of the cone pressuremeter test in clay

Analysis of the cone pressuremeter test in clay

The cone pressuremeter test is a new in situ test which combines a standard cone penetrometer with a pressuremeter. An analysis of the cone pressuremeter test in clay is presented. The analysis shows that important information about soil properties can be gained from the unloading section of the pressuremeter curve, as well as the loading section. Seven tests using a prototype cone pressuremeter are analysed using the new method, and the derived soil parameters are compared with other tests at the same site. The analysis is shown to fit closely the behaviour observed in the tests, and the derived values of shear modulus and undrained strength agree well with the results of other tests. Le nouvel essai au pressiomètre à cône combine un pénétromètre à cône de type standard avec un pressiomètre. L'article présente une analyse de l'essai au pressiomètre à cône dans l'argile. L'analyse demontre que des indications importantes au sujet des propriétés du sol peuvent s'acquerir à partir des zones de déchargement et de chargement de la courbe de pressiomètre. Sept essais employant un pressiomètre a cône prototype sont analysés par la nouvelle méthode et les para-metres de sol calculés sont compares avec d'autres essais au même emplacement. On de´ontre que l'analyse correspond bien au comportement observé au cours des essais et que les valeurs calculées du module de cisaillement et de la résistance dans l'etat non-drainé s'accordent bien avec les re sultats d'autres essais.

Modeling Rate Effects and Cyclic Loads With the Pressuremeter

A relatively new tool, the cone pressuremeter (CPMT), was used in order to evaluate its usefulness in predicting the effects on soil due to various rates of loading and to repetitive loading. Field tests were conducted in two phases. The first phase included 24 CPMT tests, at the Texas A&M University research annex, which were designed to show 1) if the CPMT could be used to predict the effects on the soil due to both rate effects and repetitive loads; and 2) if the CPMT should be inserted into a prebored hole to the desired test depth or if the CPMT should be driven to the desired test depth. The soils at the research annex were a clay and a sand. The second phase included 32 CPMT tests at three sites throughout the state of Texas. Two of the sites were clay and the third site was sand. The CPMT test used at these sites was devised so that both rate effect and cyclic effect could be determined from a single test. Rate effects on the soil modulus were modeled using a viscoelastic model of the form EstEso=ttto−ncrp(1) while repetitive load effects on the soil modulus were modeled using a power law of the form EsNEs1=N−n(2) It was concluded that a single CPMT test could be used to model both rate effects and cyclic effects on the soil modulus and that the most consistent method of inserting the probe was to place it in a prebored hole. It was also concluded that a linear relationship exists between the exponents n in both modeling equations and the normalized CPMT stress level.