Impact d’un traitement à la chaux, au ciment ou à base d’argile sur l’érodabilité d’un limon compacté

L’objectif principal de ce travail est d’étudier l’impact des traitements au ciment, à la chaux ou avec des argiles, des sols compactés sur leurs caractéristiques d’érosion interne. Un nouveau dispositif d’étude de l’érosion interne modifié et amélioré a été conçu pour quantifier les effets de différents traitements sur l’évolution de la résistance à l’érosion interne du limon de Saint-Quentin compacté. Les résultats montrent que l’impact des différents traitements sur les caractéristiques d’érosion de ce limon se traduit principalement par une augmentation de la contrainte critique. Cette augmentation est plus grande avec l’augmentation du dosage, et dans le cas du traitement au ciment. De plus, pour les traitements avec la chaux et le ciment, la contrainte critique tend à augmenter avec le temps de cure. Par ailleurs, le coefficient d’érosion est affecté uniquement par le traitement à la bentonite dans le cas d’utilisation d’un grand dosage de traitement

Estimation of the shear strength of a coarse soil with high fines content by parallel gradation method

The determination of the mechanical properties of soils containing particles larger than the allowable size of standard laboratory equipments is complex. It is indeed necessary to remove the coarsest fraction to carry out the tests. This scalping poses a problem of reliability of the results at the scale of the structure. Parallel gradation is the method commonly used for estimating the shear strength of heterogeneous granular soils from tests on their finer fraction. However, the effect of high fines content on the estimation of shear strength by this method is not well understood. The results of this study show that the parallel gradation method can predict the friction angle of the initial soil with high fines content when the modelled soil has a similar skeleton as the initial soil. However, the cohesion of the initial soil is overestimated

Utilisation des objets connectés en recherche clinique

International audienc

A Comparison of Two LDL Cholesterol Targets after Ischemic Stroke

International audienceBACKGROUND: The use of intensive lipid-lowering therapy by means of statin medications is recommended after transient ischemic attack (TIA) and ischemic stroke of atherosclerotic origin. The target level for low-density lipoprotein (LDL) cholesterol to reduce cardiovascular events after stroke has not been well studied. METHODS: In this parallel-group trial conducted in France and South Korea, we randomly assigned patients with ischemic stroke in the previous 3 months or a TIA within the previous 15 days to a target LDL cholesterol level of less than 70 mg per deciliter (1.8 mmol per liter) (lower-target group) or to a target range of 90 mg to 110 mg per deciliter (2.3 to 2.8 mmol per liter) (higher-target group). All the patients had evidence of cerebrovascular or coronary-artery atherosclerosis and received a statin, ezetimibe, or both. The composite primary end point of major cardiovascular events included ischemic stroke, myocardial infarction, new symptoms leading to urgent coronary or carotid revascularization, or death from cardiovascular causes. RESULTS: A total of 2860 patients were enrolled and followed for a median of 3.5 years; 1430 were assigned to each LDL cholesterol target group. The mean LDL cholesterol level at baseline was 135 mg per deciliter (3.5 mmol per liter), and the mean achieved LDL cholesterol level was 65 mg per deciliter (1.7 mmol per liter) in the lower-target group and 96 mg per deciliter (2.5 mmol per liter) in the higher-target group. The trial was stopped for administrative reasons after 277 of an anticipated 385 end-point events had occurred. The composite primary end point occurred in 121 patients (8.5%) in the lower-target group and in 156 (10.9%) in the higher-target group (adjusted hazard ratio, 0.78; 95% confidence interval, 0.61 to 0.98; P = 0.04). The incidence of intracranial hemorrhage and newly diagnosed diabetes did not differ significantly between the two groups. CONCLUSIONS: After an ischemic stroke or TIA with evidence of atherosclerosis, patients who had a target LDL cholesterol level of less than 70 mg per deciliter had a lower risk of subsequent cardiovascular events than those who had a target range of 90 mg to 110 mg per deciliter. (Funded by the French Ministry of Health and others; Treat Stroke to Target ClinicalTrials.gov number, NCT01252875.)