Roland Gourves

Penetration Test Modelling in a Coarse Granular Medium

Penetration test is a simple and useful test to characterize soils and granular materials. Several studies have shown the link between cone penetration resistance and density for a given material if the relation connecting these two parameters has been established beforehand. A granular materials bank currently including more than 35 granular materials has been developed to this end. Unfortunately, to be able to generalize and cover the broadest possible material range, it would be necessary to multiply the tests and the number of materials. Moreover in coarse granular media, it is necessary to carry out a large number of tests in order to achieve a reliable relation between density and cone resistance.Consequently, being able to model this test in a realistic way will enable increasing the number of tests on a material and carry out more precise parametric studies to evaluate the influence of any parameter on the test response. This article presents the work carried out to model a penetration test within...

Learning Method for In-Situ Soil Classification Based on Texture Characteristics

Knowing the nature of a soil through its classification is a key step in understanding its behaviour. In addition to its mechanical properties, information on soil type is important for forecasting material behaviour. This requires laboratory tests that are often long and expensive. Our approach is a development of in-situ identification tests used to complement “blind” mechanical tests. A new method is proposed for obtaining in-situ soil classification based on the use of geo-endoscopy and image analysis. This technique is based on the computation of texture features in geoendoscopic images and, more particularly, second order statistical features. After a presentation of the goals of this research, this article presents the methodology proposed and the learning steps performed to achieve these goals. The second part describes the testing and selection of major textural features according to their performances and their discriminating capacities. In the last part the classification results obtained with this methodology are presented. Soil image classification has been tested successfully and achieves accuracy of over 80 % in classifying natural soil samples. Because of the fixed magnification of the camera, results presented here are strongly linked to this magnification.

Use of a Variable Energy Penetrometer and Geo-Endoscopic Imaging in the Performance Assessment of Working Platforms Constructed with Large Size Unconventional Aggregates

Transportation agencies commonly use large size aggregates, often referred to as rock cap or aggregate subgrade, e.g., by Illinois Department of Transportation (IDOT), for stabilizing weak subgrades at wet of optimum moisture states. Adequate characterization of these large rocks is not possible in the laboratory with the use of standard tests. Accordingly, a cone penetration based strength index is the best field assessment tool since shear strength profile is closely linked to unbound aggregate or aggregate subgrade layer performance. To this end, an innovative variable energy dynamic cone penetration (DCP) device, popularly known as PANDA in France, was utilized in a recent Illinois Center for Transportation (ICT) research study involving the performance assessment of large size aggregates over soft subgrades. Twelve full scale working platform sections were constructed with six different types of virgin and recycled large size aggregate materials. Accelerated pavement testing (APT) was carried out on these sections to monitor the rutting progression with number of passes of a certain wheel load assembly. To evaluate layer properties and adequately relate them to rutting performance, PANDA tests were conducted along with traditional DCP soundings on the loading applied pavement test section centerlines. A geo-endoscopic probe was also used in the holes opened by the PANDA tests to identify layer interfaces and visually document subsurface moisture conditions. The PANDA and geo-endoscopy testing has proven very beneficial in the performance assessment of the large size aggregate subgrade materials under simulated traffic loading. This paper presents current detailed technical knowledge on the PANDA and geo-endoscopy test equipment and highlights field results associated with the recent ICT project soundings conducted in the pavement working platform test sections.

Application of PANDA and Geo-Endoscopy Techniques for Improved Assessment of Track Substructure Conditions at Railroad Bridge Approaches

An advanced technology for measuring track substructure conditions has been developed by Sol Solution in France. This technology, referred to as the PANDA® and Geo-Endoscopy® technique, comprises driving a variable energy cone penetration device into the track substructure using an instrumented anvil to collect strength (and modulus by correlation) profile with depth. Condition monitoring of the track substructure layers is accomplished through insertion of a camera into the same hole, also called Geoendoscopy®. The tests are commonly faster than Dynamic Cone Penetration (DCP) testing and cause negligible damage to the track substructure with the use of light and portable devices. This paper presents data from PANDA® and Geo-Endoscopy® testing efforts recently carried out under the scope of an ongoing research study at the University of Illinois. The primary objective was to relate the substructure layer properties to plastic layer deformations measured through advanced geotechnical instrumentation. Combined analysis of the PANDA®, Geo-Endoscopy®, and field instrumentation data has been used to highlight the reliability of this innovative technique towards improved evaluation of track substructure layer conditions.Copyright

Géoendoscopie: caractérisation des géomatériaux par traitement et analyse d'images

ABSTRACT Geoendoscopy is a new technique for geomaterials characterisation. It is based on the use of an endoscop and different tools of signal treatment and image analysis. Moreover this field technique brings low trauma. After a presentation of the geoendoscopy development context and a description of its realisation, parameters used today to characterize granular media are briefly described. Second part of the article deals with a presentation of the new and future improvements then real study cases in several application fields are presented.

Methodology for Confirming the Micropiles Service Performance Based on Dynamic Tests

AbstractThe uplift load test is the most widely used technique for assessment of the performance of micropiles. Although this static load test is easy to perform and interpret, it is expensive, slo...