SUMMARYThis paper is dedicated to the identification of constitutive parameters of the Mohr-Coulomb constitutive model from in situ geotechnical measurements. A pressuremeter curve and the horizontal displacements of a sheet pile wall retaining an excavation are successively used as measurements. Two kinds of optimization algorithms are used to minimize the error function, the first one based on a gradient method and the second one based on a genetic algorithm. The efficiency of each algorithm related to the error function topology is discussed. Finally, it is shown that the use of a genetic algorithm to identify the soil parameters seems particularly suitable when the topology of the error function is complex.

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Cardiovascular complications are a major cause of morbidity and mortality in patients with acromegaly. Normalization of GH secretion is associated with an improvement in structural and functional cardiac abnormalities. However, the long-term cardiac effects of treatment for acromegaly have not been studied in patients who have already developed chronic congestive heart failure (CHF). We reviewed the charts of 330 consecutive patients with acromegaly treated in two French and Belgian centers since 1985. Ten patients with both acromegaly and CHF (eight men, two women, mean age 49.7 yr) were studied retrospectively. One of them was excluded because CHF was due to severe aortic stenosis.CHF (New York Heart Association stages III-IV and echocardiography showing dilated hypokinetic cardiomyopathy with left ventricular systolic dysfunction and a left ventricular ejection fraction less than 45%) was diagnosed before, concomitantly, or after acromegaly in, respectively, two, five, and two patients. Three patients were referred with terminal heart failure requiring transplantation.One patient had transient CHF associated with a hypertensive crisis. The other eight patients had symptomatic chronic CHF. Control of GH hypersecretion failed, totally or partially, in three patients: one had a long-term survival, and the two others died at 1 and 5 yr. Good GH control was achieved in five patients: four of these are still alive 2-16 yr after diagnosis of CHF, their clinical status is stable or improved, and their quality of life is good. Overall, the 1- and 5-yr mortality (or transplantation) rates for patients with chronic symptomatic CHF were 25% (2 of 8 patients) and 37.5% (3 of 8 patients), respectively. In conclusion, less than 3% of acromegalic patients developed CHF in this study. Although effective treatment of acromegaly improved short-term cardiovascular status, its impact on long-term survival is questionable.

SUMMARYThis study concerns the identification of constitutive models from geotechnical measurements by inverse analysis. Soil parameters are identified from measured horizontal displacements of sheet pile walls and from a measured pressuremeter curve. An optimization method based on a genetic algorithm (GA) and a principal component analysis (PCA), developed and tested on synthetic data in a previous paper, is applied. These applications show that the conclusions deduced from synthetic problems can be extrapolated to real problems. The GA is a robust optimization method that is able to deal with the non-uniqueness of the solution in identifying a set of solutions for a given uncertainty on the measurements. This set is then characterized by a PCA that gives a first-order approximation of the solution as an ellipsoid. When the solution set is not too curved in the research space, this ellipsoid characterizes the soil properties considering the measured data and the tolerate margins for the response of the numerical model. Besides, optimizations from different measurements provide solution sets with a common area in the research space. This intersection gives a more relevant and accurate identification of parameters. Finally, we show that these identified parameters permit to reproduce geotechnical measurements not used in the identification process.

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SUMMARYThis study concerns the identification of parameters of soil constitutive models from geotechnical measurements by inverse analysis. To deal with the non-uniqueness of the solution, the inverse analysis is based on a genetic algorithm (GA) optimization process. For a given uncertainty on the measurements, the GA identifies a set of solutions. A statistical method based on a principal component analysis (PCA) is, then, proposed to evaluate the representativeness of this set. It is shown that this representativeness is controlled by the GA population size for which an optimal value can be defined. The PCA also gives a first-order approximation of the solution set of the inverse problem as an ellipsoid. These developments are first made on a synthetic excavation problem and on a pressuremeter test. Some experimental applications are, then, studied in a companion paper, to show the reliability of the method.

The drilling of galleries induces damage propagation in the surrounding medium and creates, around them, the Excavation Damaged Zone, EDZ. The prediction of the extension and fracture structure of this zone remains a major issue especially in the context of underground nuclear waste storage. Experimental studies on geomaterials indicate that localised deformation in shear band mode usually appears prior to fractures. Thus, the excavation damaged zone can be modelled by considering the development of shear strain localisation bands. In the classical finite element framework, strain localisation suffers of a mesh-dependency problem. Therefore, an enhanced model with a regularisation method is required to correctly model the strain localisation behaviour. Among the existing methods, we choose the coupled local second gradient model. We extend it to unsaturated conditions and we include the solid grain compressibility. Furthermore, air ventilation inside underground galleries engenders a rock-atmosphere interaction that could influence the damaged zone. This interaction has to be investigated in order to predict the damaged zone behaviour. Finally, a hydro-mechanical modelling of a gallery excavation in claystone is presented and leads to a fairly good representation of the EDZ. The main objectives of this study are to model the fractures by considering shear strain localisation bands and to investigate if an isotropic model accurately reproduces the in situ measurements. The numerical results provide information about the damaged zone extension, structure and behaviour that are in very good agreement with in situ measurements and observations. For instance, the strain localisation bands develop in chevron pat-B. Pardoen * · S. Levasseur · F. Collin Université de Liège, Département ArGEnCo, Chemin des Chevreuils 1, 4000 Liège, Belgium Tel.: +32-4-3662033 E-mail: b.pardoen@ulg.ac.be * FRIA, F.R.S.-FNRS scholarship holder tern during the excavation and rock desaturation is observed close to the gallery due to air ventilation.

a b s t r a c tA zone with significant irreversible deformations and significant changes in flow and transport properties is expected to be formed around underground excavations in indurated clay. The stress perturbation around the excavation could lead to a significant increase of the permeability, related to diffuse and/or localised crack propagation in the material. The main objective of this study is to model these processes at large scale in order to assess their impacts on the performance of radioactive waste geological repositories. This paper concerns particularly the hydro-mechanical modelling of a long-term dilatometer experiment performed in Mont Terri Rock Laboratory in Switzerland. The proposed model defines the permeability as a function of the aperture of the cracks that are generated during the excavation. With this model, the permeability tensor becomes anisotropic. Advantages and drawbacks of this approach are described using the results of the Selfrac long-term dilatometer experiment.