Grouting is an effective method to strengthen weak rock mass in tunnel engineering to prevent and control mud inrush disaster. The hardened grout-rock consolidation involves not only the properties of hardened grout, but also that of weak rock masses. As a transition region between them, the grout-rock interface determines the overall strength, then the shear properties of which was investigated in this study. The gushed mud from engineering project and a kind of Portland cement grout were selected as raw materials. A test system that can apply high injection pressure was developed to simulate the actual generation environment of grout-rock interface. By using it, two sets of samples with three different water-to-cement (W/C) ratios: 0.8, 1 and 1.5; and three different injection pressures: 1 MPa, 1.5 MPa and 2 MPa were prepared. After that, the direct shear test and SEM test were conducted to study the properties of grout-rock interface. The results show that lower W/C ratio and higher injection pressure can result in larger cohesive strength as well as internal friction angle of samples. When W/C ratio was decreased from 1.5 to 0.8, the former increased from 171.95 kPa to 251.55 kPa, and the latter rose from 32.31° to 41.71°. Also, they increased by 73.59 % and 17.64 %, respectively, with injection pressure ranging from 1 MPa to 2 MPa. It is hoped that the data provided will aid in the design of grouting with this material in the future.
Background Plastic bronchitis (PB) is a rare and severe lung disease. It can be triggered by influenza virus infection, which is a common respiratory infection in children. Bronchoscopy can aid in the early detection and treatment of PB. However, the outcomes and risk for PB development in pediatric patients with influenza virus infection are not fully understood. Methods Data from 321 children diagnosed with influenza virus pneumonia who underwent bronchoscopy examinations between 1st January, 2009 and 31st December, 2020 were retrospectively analyzed to assess the outcomes and risk factors associated with PB development. Results This study included 97 girls and 224 boys with influenza virus pneumonia with a median age of 42 months. Among them, 36 patients (11.2%) were categorized as having PB based on bronchoscopy findings. PB patients had significantly longer fever durations ( p =0.010) and higher risks of developing severe conditions including respiratory failure ( p <0.001), acute respiratory distress syndrome ( p <0.001), and air-leak syndrome ( p <0.001) compared to non-PB patients. Conventional treatment including the use of neuraminidase inhibitors and antibiotics did not differ between the PB and non-PB patients, but PB patients required more anti-inflammatory treatment ( p =0.019) and ventilator support ( p <0.001). Combined univariate and multivariate analyses suggested that radiographic findings, including mediastinal emphysema ( p =0.012) and lung consolidation ( p =0.012), as well as increased levels of neutrophils ( p =0.026), aspartate aminotransferase ( p =0.004), and lactate dehydrogenase ( p <0.001), were identified as risk factors for PB development in patients with influenza virus pneumonia. Although PB patients required more intensive care and had longer hospital stays, they all recovered well after treatment. Conclusion Influenza virus infection is linked to PB development in children. Identifying risk factors and early intervention such as bronchoscopy can improve the prognosis of children with PB.
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