Théo Besson, C. Jacquard, M. Rispal, Philippe Reiffsteck, F. Szymkiewicz
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引用次数: 0
Abstract
Borehole expansion tests such as the Ménard pressuremeter test (PMT) are widely used in geotechnical testing as they provide a modulus that can be used to estimate settlements under geotechnical structures. This paper describes a new soil investigation apparatus that performs an expansion test in a prebored hole called the dilatometer Fondasol test (DFT). From this test, an in situ load-displacement curve is obtained in the same manner as the PMT. The apparatus is based on the concept of the rigid dilatometer used in rock mechanics with two rigid and semicylindrical shells spread against the borehole walls. Four different prototypes have been developed and successfully tested on Hostun sand reconstituted by vibration in a test chamber at a density index varying from 0.18 to 0.72. Results show that despite the significant differences in the shells’ geometry, they have little impact on the measurement of an apparent modulus. Three different formulas derived from elastic theory have been evaluated for the computation of dilatometer moduli: EDFT;M, EDFT;G, and EDFT;BJ. A comparative study with pressuremeter tests shows that EDFT;M and EDFT;BJ are close to the pressuremeter moduli EPMT;M with a ratio EPMT/EDFT ranging between 1.2 and 0.8 depending on the density of the sand. The moduli EDFT;G are significantly higher than EPMT;M and vary importantly depending on the prototypes. Dilatometer’s load-displacement curves show that global failure occurs at higher stresses than with the pressuremeter.
期刊介绍:
The purpose of the Geotechnical Testing Journal is (1) to provide a high-quality publication that informs the profession of new developments in soil and rock testing and related fields; (2) to provide a forum for the exchange of information, particularly that which leads to the development of new test procedures; and (3) to stimulate active participation of the profession in the work of ASTM International Committee D18 on Soil and Rock and related information.
The editorial scope of this journal covers test methods for soil and rock, sampling, nomenclature, and practices relating to the determination of properties and behavior of soil and rock for engineering purposes, and for soil as a medium for plant growth.