Some Remarks on the Seismic Design of Multipropped Retaining Walls

The behavior under seismic condition of embedded retaining structures is quite complex. When the geometry (prop levels) prevents the formation of kinematic mechanisms and the structural elements do not achieve yield strength conditions, permanent displacements are expected to be relatively low and, therefore, seismic actions may cause significant increases of the forces acting on the structures: these forces are dependent on a number of factors such as the characteristics of the ground motion, the problem geometry, the mechanical behavior of the soil and the soil-structure relative stiffness. In the present study, the results of several dynamic numerical analyses of a multi-propped retaining wall in a dry coarse soil are presented and discussed. The results of the analyses indicate that large structural stresses (bending moments in walls and axial loads on props) develop as consequence of seismic actions. Post seismic stresses remain significantly large as compared to the static condition. The maximum ground acceleration in the free-field seems not to be an effective parameter in order to evaluate the seismic performance of this kind of retaining structures

Granulomatous Lymphocytic Interstitial Lung Disease (GLILD) in Common Variable Immunodeficiency (CVID): A Multicenter Retrospective Study of Patients From Italian PID Referral Centers

Background: Granulomatous and Lymphocytic Interstitial Lung Diseases (GLILD) is a severe non-infectious complication of Common Variable Immunodeficiency (CVID), often associated with extrapulmonary involvement. Due to a poorly understood pathogenesis, GLILD diagnosis and management criteria still lack consensus. Accordingly, it is a relevant cause of long-term loss of respiratory function and is closely associated with a markedly reduced survival. The aim of this study was to describe clinical, immunological, laboratory and functional features of GLILD, whose combination in a predictive model might allow a timely diagnosis. Methods: In a multicenter retrospective cross-sectional study we enrolled 73 CVID patients with radiologic features of interstitial lung disease (ILD) associated to CVID (CVID-ILD) and 125 CVID patients without ILD (controls). Of the 73 CVID-ILD patients, 47 received a definite GLILD diagnosis while 26 received a clinical-radiologic diagnosis of CVID related ILD defined as uILD. Results: In GLILD group we found a higher prevalence of splenomegaly (84.8 vs. 39.2%), autoimmune cytopenia (59.6 vs. 6.4%) and bronchiectasis (72.3 vs. 28%), and lower IgA and IgG serum levels at CVID diagnosis. GLILD patients presented lower percentage of switched-memory B cells and marginal zone B cells, and a marked increase in the percentage of circulating CD21lo B cells (14.2 vs. 2.9%). GLILD patients also showed lower total lung capacity (TLC 87.5 vs. 5.0%) and gas transfer (DLCO 61.5 vs. 5.0%) percent of predicted. By univariate logistic regression analysis, we found IgG and IgA levels at CVID diagnosis, presence of splenomegaly and autoimmune cytopenia, CD21lo B cells percentage, TLC and DCLO percent of predicted to be associated to GLILD. The joint analysis of four variables (CD21lo B cells percentage, autoimmune cytopenia, splenomegaly and DLCO percent of predicted), together in a multiple logistic regression model, yielded an area under the ROC curve (AUC) of 0.98 (95% CI: 0.95-1.0). The AUC was only slightly modified when pooling together GLILD and uILD patients (0.92, 95% CI: 0.87-0.97). Conclusions: we propose the combination of two clinical parameters (splenomegaly and autoimmune cytopenia), one lung function index (DLCO%) and one immunologic variable (CD21lo%) as a promising tool for early identification of CVID patients with interstitial lung disease, limiting the use of aggressive diagnostic procedures

Seismic Performance of Rock Slopes and Wedges Accounting for Progressive Strength Reduction of Joints

Seismic performance of slopes is typically assessed by adopting permanent displacements as significant engineering demand parameter which can be calculated with more or less refined procedures obtained removing one or more hypotheses of the well-known Newmark rigid block model. In this study we propose a numerical procedure which allows to remove the hypothesis of constant resistance along the sliding surface introducing the progressive material strength reduction (from peak to ultimate values) induced by shear displacements along the sliding interface. The proposed procedure is implemented in a computer code for two simple but instructive geometrical problems, such as the one–dimensional rock slope characterized by the presence of one planar joint and the two-dimensional problem of a rock wedge bounded by two planar joints. The implemented code was then used to carry out a parametric analysis aimed at quantifying the effects of the progressive strength reduction on the magnitude of permanent displacements induced by a selection of accelerometric records. The preliminary results of this analysis are presented and discussed

Lo scavo della stazione MarmorKirken della metropolitana di Copenhagen

Questa nota descrive il comportamento geotecnico dello scavo della stazione MarmorKirken della nuova linea Cityringen della metropolitana di Copenhagen. Lo scavo, di profondità pari a circa 35 m, è stato realizzato in stretta adiacenza a MarmorKirken, una delle opere monumentali più importanti della Danimarca. La minimizzazione degli effetti indotti dallo scavo sul monumento e la delicatezza del contesto hanno richiesto il ricorso ad una tecnica costruttiva di tipo top-down ed il continuo confronto delle previsioni di progetto con i dati di monitoraggio. Le misure hanno sostanzialmente confermato le previsioni di progetto, e, nel contempo, hanno permesso di evidenziare alcuni aspetti particolari del caso di studio. I cedimenti indotti dalla fase di costruzione dei diaframmi perimetrali hanno rappresentato un’aliquota non trascurabile dei cedimenti complessivi, mentre gli spostamenti orizzontali in profondità dei pannelli, sono risultati significativamente superiori a quelli del terreno immediatamente a tergo di essi, in ragione delle ottime caratteristiche meccaniche dell’ammasso calcareo presente a partire da circa 20 m di profondità