Advances in the Construction and Design of Jet Grouting Methods in South America

This paper presents a brief historical development of the two most popular jet grouting methods used in South America, namely, the chemical churning pile method (CCP) and jumbo jet grouting. Advantages and limitations of each procedure are cited. A brief discussion follows covering the history of CCP jet grouting in South America. Field trials performed to improve the design methodology and construction of CCP and jumbo jet grouted columns are presented. Finally, three case histories are presented to illustrate the use of jumbo jet grouting where limited head room exists, jet grouting in close proximity to pile supported structures, formation of a diaphragm wall in gravelly soil with boulders. The paper closes with a short discussion of a recent tunnel project in which horizontal jet grouting is used as the temporary tunnel support

Influence of fore-arc structure on the extent of great subduction zone earthquakes

Author Posting. © American Geophysical Union, 2007. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 112 (2007): B09301, doi:10.1029/2007JB004944.Structural features associated with fore-arc basins appear to strongly influence the rupture processes of large subduction zone earthquakes. Recent studies demonstrated that a significant percentage of the global seismic moment release on subduction zone thrust faults is concentrated beneath the gravity lows resulting from fore-arc basins. To better determine the nature of this correlation and to examine its effect on rupture directivity and termination, we estimated the rupture areas of a set of Mw 7.5–8.7 earthquakes that occurred in circum-Pacific subduction zones. We compare synthetic and observed seismograms by measuring frequency-dependent amplitude and arrival time differences of the first orbit Rayleigh waves. At low frequencies, the amplitude anomalies primarily result from the spatial and temporal extent of the rupture. We then invert the amplitude and arrival time measurements to estimate the second moments of the slip distribution which describe the rupture length, width, duration, and propagation velocity of each earthquake. Comparing the rupture areas to the trench-parallel gravity anomaly (TPGA) above each rupture, we find that in 11 of the 15 events considered in this study the TPGA increases between the centroid and the limits of the rupture. Thus local increases in TPGA appear to be related to the physical conditions along the plate interface that favor rupture termination. Owing to the inherently long timescales required for fore-arc basin formation, the correlation between the TPGA field and rupture termination regions indicates that long-lived material heterogeneity rather than short timescale stress heterogeneities are responsible for arresting most great subduction zone ruptures.A. Llenos was supported by a National Defense Science and Engineering Graduate fellowship

Communication and visiting policies in Italian intensive care units during the first COVID-19 pandemic wave and lockdown: a nationwide survey

Background: During the first coronavirus disease 2019 (COVID-19) pandemic wave, an unprecedented number of patients with respiratory failure due to a new, highly contagious virus needed hospitalization and intensive care unit (ICU) admission. The aim of the present study was to describe the communication and visiting policies of Italian intensive care units (ICUs) during the first COVID-19 pandemic wave and national lockdown and compare these data with prepandemic conditions. Methods: A national web-based survey was conducted among 290 Italian hospitals. Each ICU (active between February 24 and May 31, 2020) was encouraged to complete an individual questionnaire inquiring the hospital/ICU structure/organization, communication/visiting habits and the role of clinical psychology prior to, and during the first COVID-19 pandemic wave. Results: Two hundred and nine ICUs from 154 hospitals (53% of the contacted hospitals) completed the survey (202 adult and 7 pediatric ICUs). Among adult ICUs, 60% were dedicated to COVID-19 patients, 21% were dedicated to patients without COVID-19 and 19% were dedicated to both categories (Mixed). A total of 11,102 adult patients were admitted to the participating ICUs during the study period and only approximately 6% of patients received at least one visit. Communication with family members was guaranteed daily through an increased use of electronic devices and was preferentially addressed to the same family member. Compared to the prepandemic period, clinical psychologists supported physicians more often regarding communication with family members. Fewer patients received at least one visit from family members in COVID and mixed-ICUs than in non-COVID ICUs, l (0 [0–6]%, 0 [0–4]% and 11 [2–25]%, respectively, p < 0.001). Habits of pediatric ICUs were less affected by the pandemic. Conclusions: Visiting policies of Italian ICUs dedicated to adult patients were markedly altered during the first COVID-19 wave. Remote communication was widely adopted as a surrogate for family meetings. New strategies to favor a family-centered approach during the current and future pandemics are warranted

Management of critically ill patients with coviD-19: suggestions and instructions from the coordination of intensive care units of lombardy

With 63,098 confirmed cases on 17 April 2020 and 11,384 deaths, Lombardy has been the most affected region in Italy by coronavirus disease 2019 (coviD-19). to cope with this emergency, the coviD-19 lombardy intensive care units (ICU) network was created. The network identified the need of defining a list of clinical recommendations to standardize treatment of patients with COVID-19 admitted to Intensive Care Unit (ICU). Three core topics were identified: 1) rational use of intensive care resources; 2) ventilation strategies; 3) non-ventilatory interventions. Identification of patients who may benefit from ICU treatment is challenging. Clinicians should consider baseline performance and frailty status and they should adopt disease-specific staging tools. Continuous positive airway pressure, mainly delivered through a helmet as elective method, should be considered as initial treatment for all patients with respiratory failure associated with coviD-19. in case of persisting dyspnea and/or desaturation despite 4-6 hours of noninvasive ventilation, endotracheal intubation and invasive mechanical ventilation should be considered. in the early phase, muscle relaxant use and volume-controlled ventilation is recommended. Prone position should be performed in patients with Pao2/Fio2≤100 mmHg. For patients admitted to icU with coviD-19 interstitial pneumonia, we do not recommend empiric antibiotic therapy for community-acquired pneumonia. consultation of an infectious disease specialist is suggested before start of any antiviral therapy. In conclusion, the COVID-19 Lombardy ICU Network identified a list of best practice statements supported b