Implicaciones geotécnicas de la construcción del metro de Dubai comparadas con las que supone la construcción del metro de Bogotá

Este estudio se lleva a cabo con el fin de establecer las diferencias que se tienen en el proceso constructivo del metro existente en la ciudad de Dubái y el metro que se construirá en la ciudad de Bogotá, estos dos lugares presentan naturalezas diferentes en la formación de sus estratos geológicos . La ciudad de Dubái cuenta con suelos arenosos de compacidad suelta (calcarenitas, limolitas) y la ciudad de Bogotá cuenta con suelos arcillosos de consistencia baja. En la ciudad de Bogotá se puede establecer según los estudios realizados por el instituto de desarrollo urbano (IDU), que la concentración de agua existente en el suelo es alta y por tal motivo se requiere de un tratamiento particular, donde se pueden implementar algunas metodologías de estabilización del suelo, en consecuencia, se puede establecer debido a los estudios realizados que el mejor tipo de metro para la ciudad de Bogotá debería ser de forma elevada. Este informe de investigación se realiza principalmente con estudios anteriores al finalmente establecido, comparando sistemas constructivos para metros combinados. La importancia de la realización de este trabajo, es la identificación de las implicaciones que tuvieron en la construcción de metro de Dubái en aspectos geotécnicos como son: los diseños de cimentación (uso de pilas de tensión y uso de pasadores de carga para los viaductos), aspectos que en el diseño geotécnico a menudo están relacionados con las características de los materiales del subsuelo y la naturaleza del agua subterránea y aspectos como el asentamiento elástico en suelos cohesivos y granulares teniendo en cuenta el tipo de tuneladora a implementar y la profundidad de la línea de metro. Esta comparación se realiza entre dos estaciones del metro de Dubái ( Burjuman y City Center) estaciones construidas subterráneamente a 30 ms de profundidad y los tramos 1 y 4 a través de toda la línea del metro, donde se encuentran materiales lacustres, características especiales que dan un tratamiento particular al sistema constructivo a implementar y dando una perspectiva de las posibles dificultades que se pueden llegar a tener en la construcción del metro, y que la ciudad de Dubái a través de la construcción de sus tres líneas de metro ya soluciono.This study is carried out in order to establish the differences that exist in the constructive process of the existing metro in the city of Dubai and the metro that will be built in the city of Bogotá, these two places present different forms in the formation of the nature of its geological strata. The city of Dubai has sandy soils of loose compactness (calcarenitas, siltstones) and the city of Bogotá has clay soils of low consistency. In the city of Bogotá it can be established, according to the studies carried out by the Urban Development Institute (IDU), that the concentration of water in the soil is high and for that reason a particular treatment is required, where some methodologies can be implemented Soil stabilization, therefore, can be configured to studies that the best type of metro for the city of Bogotá should be high. This research report is mainly carried out with studies previous to the one finally established, comparing constructive systems for combined meters. The importance of the realization of this work, the identification of the implications that they had in the construction of the Dubai metro in geotechnical aspects such as the son: traction designs and use of load pins for the viaducts, aspects that in the geotechnical design they are often related to the characteristics of subsoil materials and the nature of groundwater and aspects such as elastic settlement in cohesive and granular soils, taking into account the type of tunneling machine to be implemented and the depth of the subway line. This comparison is made between the metro stations of Dubai (Burjuman and City Center) stations built underground at 30 m depth and sections 1 and 4 through the entire metro line, where the lacustrine materials are found, special characteristics that They give a particular treatment to the constructive system to be implemented and give a perspective of the possible difficulties that may be encountered in the construction of the metro, and that the city of Dubai through the construction of its three metro lines and solution

Stoma-free Survival After Rectal Cancer Resection With Anastomotic Leakage: Development and Validation of a Prediction Model in a Large International Cohort.

Objective:To develop and validate a prediction model (STOMA score) for 1-year stoma-free survival in patients with rectal cancer (RC) with anastomotic leakage (AL).Background:AL after RC resection often results in a permanent stoma.Methods:This international retrospective cohort study (TENTACLE-Rectum) encompassed 216 participating centres and included patients who developed AL after RC surgery between 2014 and 2018. Clinically relevant predictors for 1-year stoma-free survival were included in uni and multivariable logistic regression models. The STOMA score was developed and internally validated in a cohort of patients operated between 2014 and 2017, with subsequent temporal validation in a 2018 cohort. The discriminative power and calibration of the models' performance were evaluated.Results:This study included 2499 patients with AL, 1954 in the development cohort and 545 in the validation cohort. Baseline characteristics were comparable. One-year stoma-free survival was 45.0% in the development cohort and 43.7% in the validation cohort. The following predictors were included in the STOMA score: sex, age, American Society of Anestesiologist classification, body mass index, clinical M-disease, neoadjuvant therapy, abdominal and transanal approach, primary defunctioning stoma, multivisceral resection, clinical setting in which AL was diagnosed, postoperative day of AL diagnosis, abdominal contamination, anastomotic defect circumference, bowel wall ischemia, anastomotic fistula, retraction, and reactivation leakage. The STOMA score showed good discrimination and calibration (c-index: 0.71, 95% CI: 0.66-0.76).Conclusions:The STOMA score consists of 18 clinically relevant factors and estimates the individual risk for 1-year stoma-free survival in patients with AL after RC surgery, which may improve patient counseling and give guidance when analyzing the efficacy of different treatment strategies in future studies

Stoma-free survival after anastomotic leak following rectal cancer resection: worldwide cohort of 2470 patients

Background: The optimal treatment of anastomotic leak after rectal cancer resection is unclear. This worldwide cohort study aimed to provide an overview of four treatment strategies applied. Methods: Patients from 216 centres and 45 countries with anastomotic leak after rectal cancer resection between 2014 and 2018 were included. Treatment was categorized as salvage surgery, faecal diversion with passive or active (vacuum) drainage, and no primary/secondary faecal diversion. The primary outcome was 1-year stoma-free survival. In addition, passive and active drainage were compared using propensity score matching (2: 1). Results: Of 2470 evaluable patients, 388 (16.0 per cent) underwent salvage surgery, 1524 (62.0 per cent) passive drainage, 278 (11.0 per cent) active drainage, and 280 (11.0 per cent) had no faecal diversion. One-year stoma-free survival rates were 13.7, 48.3, 48.2, and 65.4 per cent respectively. Propensity score matching resulted in 556 patients with passive and 278 with active drainage. There was no statistically significant difference between these groups in 1-year stoma-free survival (OR 0.95, 95 per cent c.i. 0.66 to 1.33), with a risk difference of -1.1 (95 per cent c.i. -9.0 to 7.0) per cent. After active drainage, more patients required secondary salvage surgery (OR 2.32, 1.49 to 3.59), prolonged hospital admission (an additional 6 (95 per cent c.i. 2 to 10) days), and ICU admission (OR 1.41, 1.02 to 1.94). Mean duration of leak healing did not differ significantly (an additional 12 (-28 to 52) days). Conclusion: Primary salvage surgery or omission of faecal diversion likely correspond to the most severe and least severe leaks respectively. In patients with diverted leaks, stoma-free survival did not differ statistically between passive and active drainage, although the increased risk of secondary salvage surgery and ICU admission suggests residual confounding