Technical Papers

Technical Papers

Field experience of the piezoball in soft clay

C. Colreavy & C.D. O’Loughlin – Institute of Technology Sligo, Ireland
M. Long
– University College Dublin, Ireland
N. Boylan
– University of Western Australia, Australia
D. Ward
– In Situ SI, UK

ABSTRACT: This paper presents the results of a series of piezoball penetration and dissipation tests carried out at two well characterized soft soil sites in Ireland. Piezo-ball data are compared with piezocone data, in addition to other in situ and laboratory test results. Using the standard N factor of 10.5 resulted in an undrained shear strength profile which is in very good agreement with Tbar profiles from previous studies. Interestingly, results of dissipation tests show that dissipation around the pie-zoball is faster than around the cone, when the different diameters are accounted for.

Interpretation of CPTU and SDMT in organic, Irish soils

A. Bihs – NTNU, Trondheim, Norway
M. Long – UCD, Dublin, Ireland
D. Marchetti – Studio Prof. Marchetti, Roma, Italy
D. Ward – In Situ Site Investigation, UK

ABSTRACT: The Limerick South Ring road project started in August 2006 and connects the N7 Dublin Road to the N18 Ennis Road. An extensive laboratory and field soil investigation program was carried out. The soil consists of alluvial (mostly organic) fine clays and silts with thicknesses up to 13m. This paper presents the re-sults of CPTU and seismic dilatometer tests (SDMT) carried out by In Situ Site In-vestigation (In Situ SI) at two locations along the new embankment in November 2008. It is the first time that the research DMT including shear wave velocity meas-urements was tested on Irish soils. Effective stress based models developed at the NTNU have been used among several others to interpret the data from the CPTU. The results obtained are compared to the findings from the SDMT.

Cone penetration testing on liquefiable layers identification and liquefaction potential evaluation

E. Anamali – In Situ Site Investigation, Balkans
L. Dhimitri & D. Ward – In Situ Site Investigation, UK
J.J.M. Powell – Geolabs Limited, UK

ABSTRACT: This paper presents the results of liquefaction potential evaluation for various sandy sites, with high seismic risk, where soil liquefaction is a major concern for all structures supported on these kinds of soils. There are many methods available for these calculations, based on different site investigation techniques. The Cone Penetration Test (CPTU) provides ideal data for this purpose, due to its repeatability and reliability. CPTU based methods on soil liquefaction assessment are important not only to identify liquefiable layers, but also their state in situ. This paper looks at results of liquefaction analyses on different sites susceptible to liquefaction, using CPTU based methods and also compares them with methods that are Standard Penetration Test (SPT) based, but using SPT data derived from correlations to CPTU results.

Evaluation of Liquefaction Potential by CPTU and SDMT

E. Anamali – In Situ Site Investigation, Balkans
L. Dhimitri & D. Ward – In Situ Site Investigation, UK
Neritan Shkodrani – Faculty of Civil Engineering, Polytechnic University, Albania

ABSTRACT: This paper deals with the evaluation of liquefaction potential of the soils at the marsh of Porto Romano, located in the western central part of Albania, where will be constructed the Energetic Park of Porto Romano. These analyses are performed based on the data taken from different in situ testing techniques. Piezocone tests (CPTU) were carried out during the two different site investigations (before and after the ground improvement) for the characterization of soil layers and determination of soil properties. In addition, during the first phase of site investigation a full seismic study was performed to estimate the shear wave velocity, Vs, and the peak ground acceleration. During the second site investigation two seismic dilatometer Marchetti tests (SDMT) were also carried out very close to the CPTU locations. The paper shows the results of the liquefiability assessment by CPTU and SDMT tests carried out during the two site investigations.

Evaluation of bearing capacity of cast in place piles from in situ tests based methods

E. Anamali – In Situ Site Investigation, Balkans
L. Dhimitri & D. Ward – In Situ Site Investigation, UK
Neritan Shkodrani – Faculty of Civil Engineering, Polytechnic University, Albania

Different in situ based methods are used for determining the bearing capacity of a single pile. For this reason, this paper aims to deal with evaluation of bearing capacity of a single cast in place pile, by using various methods based on three different in situ testing techniques: Standard Penetration Test (SPT), Cone Penetration Test (CPT) and Dilatometer Marchetti Test (DMT). These tests are used in this study to identify the soil profile and also to characterize the strength parameters of the soils, which are further used to estimate the bearing capacity. The tests are carried out in different locations in Albania, including also some coastal areas. The soil profile identified in all the sites is non homogeneous. From site investigations are determined various sandy and clayey layers, but in the coastal sites also organic material is present. The considered cast in place pile diameters, in this paper, range from 0.5 m through 2.0 m and embedment lengths range from 10 m, 20 m and 32 m. At the end of our study, the results of bearing capacities by different methods are compared. Some conclusions are highlight related to the use of in situ tests during the pile foundation design.

Small Strain Stiffness assessments from in situ tests – revisited

E. Anamali – In Situ Site Investigation, Balkans
L. Dhimitri & D. Ward – In Situ Site Investigation, UK
A.P. Butcher –
Consultant, UK
J.J.M. Powell
Geolabs Limited, UK

ABSTRACT: The increasing trend to model the behaviour of the ground requires more detailed soil properties that include small strain data. These data can be obtained from both field and laboratory tests to measure shear wave velocities from which the shear modulus at small strains can be calculated. However, such measurements are only specified for large projects and so smaller projects have to rely on correlations from other in
situ tests. In 2004 Powell & Butcher presented and discussed some correlations between the small strain stiffness of the ground in different orientations measured by geophysical tests and parameters measured by the
Cone Penetrometer (CPT) and the Marchetti Dilatometer (DMT). Since that time the database of information has grown and this paper reviews and updates the findings of the earlier paper. Anisotropy of stiffness is shown to be a major factor in the correlations especially in ‘aged’ clays.

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