Advanced Support Measures Research Articles

Study on Excavation Stability of Loess Tunnel in Geological Weak Areas Exploring Excavation Stability of Loess Tunnels in Geologically Vulnerable Regions

As western development progresses, extensive infrastructure construction can be conducted in the Loess Region. During infrastructure construction, particularly in tunnel excavation, traversing through extensive loess formations poses a significant challenge. It is imperative to ensure the stability and integrity of the tunnel while crossing weak geological zones in loess regions. This issue should be comprehensively addressed during tunnel construction. Geological and numerical analyses were employed to analyze the impact of weak geological areas on loess tunnel excavation. These analyses focused on the mechanisms of weak geology and assessed the efficacy of advanced support measures in loess tunnel construction, specifically addressing the issues encountered within weak geological zones during the construction process. First, we examined the formation mechanism of weak geological zones in loess, which is primarily attributed to water infiltration. Subsequently, based on this formation mechanism, a finite difference numerical analysis was utilized to investigate the potential failure modes of loess tunnels passing through weak geological zones. The destruction of the tunnel in the weak geological zone resulted from sliding erosion of the surface soil, leading to the complete collapse of the soil above the tunnel. During tunneling through weak geological zones, The soil in front of the excavation initially exhibited instability, causing the overall subsidence of the entire weak band, with the formation of a trap on the surface. Finally, the effectiveness of treatment measures was assessed according to the failure pattern of the loess tunnel in the weak geological zone. The analysis results indicated that with the implementation of appropriate advanced reinforcement measures, successful crossing can be achieved during the construction of a loess tunnel traversing the weak geological zone.

Study on the Two-Step Construction Method of Super Large Cross-Section Tunnels Crossing Karst Cave Areas

To explore the solution of the two-step method applied in the rapid construction of super large cross-section tunnels passing through IV-and V-grade surrounding rock sections in karst cave areas, based on an engineering example of the Lianhuashan Tunnel, we use the numerical calculation method to analyze the stability of surrounding rock and the design parameters of the control measures for super large cross-section tunnels during the construction of the step method. The calculated results show that the working face of IV-grade surrounding rock can be stabilized by an advanced small pipe, and the stability of the supporting structure should be controlled mainly by IV-grade surrounding rock. In order to control the stability of the tunnel face, it is necessary to use an advanced large pipe shed in the surrounding V-grade rock. The reinforcement range of the advanced large pipe shed is 120° and the length is 20 m. This is the most economical design parameter of the advanced large pipe shed, ensuring the deformation control effect. For control of the stability of the supporting structure, under the condition that the working space is suitable for large machinery, the settlement of the arch of the supporting structure can be obviously reduced by shortening the step cycle footage and reducing the step length, and the peripheral convergence of the supporting structure can be obviously reduced by reducing the step height. After comprehensive analysis and considering the development of karst caves, the advanced support measures, design parameters, bench excavation design parameters, initial support measures, karst cave treatment measures, and bench construction process of IV- and V-grade surrounding rock is determined. The application verification shows that the research results have a good control effect on the stability of the surrounding rock and cave and are suitable for large-scale mechanical operations, which can significantly improve the excavation speed of the super large cross-section tunnel passing through the IV- and V-grade surrounding rock sections in the karst cave area.

Research on an automatic roadway formation method in deep mining areas by roof cutting with high-strength bolt-grouting

The excavation of deep mining roadways with traditional mining methods leads to various issues, such as the occurrence of large deformations, the waste of coal resources, complex conditions and the high cost of advanced support measures. In this study, we examined the roadway damage mechanism of the traditional gob-side entry driving method with coal pillars using the Suncun Coal Mine, the deepest mine in China, as an engineering case study. A method for the automatic formation of roadways in deep mining areas by roof cutting with high-strength bolt-grouting was proposed, and several quantitative evaluation indicators, namely, the roadway deformation control rate, anchor cable strength utilization ratio, and hydraulic prop strength utilization ratio, were established. The impacts of controlling the deformation of the surrounding rock were comparatively analysed in consideration of numerous factors, such as the mechanical parameters of the surrounding rock, roof cutting height, roof cutting angle, grouting anchor cable length, and hydraulic prop spacing. On this basis, the proposed method was applied in the field. The results showed that the automatically formed roadway cross-section exhibited decreased convergence deformation; moreover, the roof deformation was effectively controlled, and the passive hydraulic prop supports could be effectively replaced with the active support of grouting anchor cables, verifying the effect of the proposed method.

EURECA Serbia ONE 2014: Out of hospital cardiac arrest: Venue of accident

Introduction: Data on the success of advanced support measures đivoru indicate that in well organised systems more than 35% of people in cardiac arrest experience re-establishment of spontaneous circulation (ROSC). Percentage of established ROSC according to the data published by the Eureca program in 2014 in Serbia is around 5%. In Serbia, there is no reliable system of collecting data that is linked to the place of the event and the presence of a witness to what we call Out hospital cardiac arrest. (OHCA), whether it is sudden cardiac arrest or heart failure. The EURECA study should shed light on the epidemiological picture in the Republic of Serbia and provide an objective overview of the cite of events of sudden cardiac arrest in Serbia as very important information for the development of a strategy for treating this disease. OBJECTIVE: To determine the place of event in sudden cardiac arrest in accordance with the Utstain protocol. The aim of the protocol is to determine whether the presence of a witness in sudden cardiac arrest affects the number of attempts of resuscitation by the system of Emergency Medical Assistance in Serbia. METHOD: A prospective study that includes data collected through questionnaires, established within the framework of the adopted methodology for collecting data in Clinical Trials ID: NCT02236819 - ONE Eureca 2014. Data from the program defined by the research centers was entered into a database uniquely formed on the Internet at www.eureca.rs Results: In the framework of Eureca in 2014 in Serbia data was collected for around 1828 cardiac arrests that occurred outside the hospital. 789/1828 or 48.46 cardiac arrests took place in the presence of a witness, others were unwitnessed or 839 people had suffered cardiac arrest in a remote area. Resuscitation measures were initiated by the Emergency medical unit at 171/839 or 20.42% of patients have experienced cardiac arrest without the presence of relatives or bystanders. The largest number of cardiac arrests take place in a house or an apartment of a patient 1448/1828 79.21% and with a witness present 629/1448 or in 43.41% of cases. The data collected is related to the recorded heart failures in retirement homes, workplaces, public buildings, street sports facilities. Cardiac arrest in a public place - the street is next in frequency 133/1828 or 7.27% of all cardiac arrests outside of hospitals. Conclusion: A large number of cardiac arrests occur in the home, often without a witness or a person that could activate the emergency service. Further studies of the structure of age, education, number of people in households can provide an answer about the activities that should be taken. Future studies should be designed to shed light on this phenomenon.

Infección invasiva por Streptococcus pneumoniae. Síndrome de Austrian: reporte de caso

Austrian syndrome is defined as the triad consisting of pneumonia, endocarditis and meningitis due to invasive Streptococcus pneumoniae infection. Few case reports have been reported since its first description in 1975 by Robert Austrian, mainly because it is rarely observed. Below we report the case of a 61 year-old male patient who presented with bacterial meningitis due S. pneumoniae followed by bacterial pneumonia and severe mitral regurgitation, associated with four vegetations on the atrial surface of the posterior mitral leaflet; in addition, there was rupture and prolapse of its middle scallop. The S. pneumoniae bacterium was isolated from cerebrospinal fluid and blood cultures. In consequence, the patient was given broad-spectrum antibiotic therapy and had an early valve replacement performed, obtaining a good clinical outcome. The key prognostic factor of the Austrian syndrome is determined by the damage of cardiac valves, particularly in patients with a compromised aortic valve; hence, it is necessary to identify the degree of valve injury and define surgical and antibiotic treatment on a timely fashion. However, in subacute, less frequent clinical cases where the mitral valve is the main valve compromised, usually a directed antibiotic therapy associated with advanced support measures are sufficient to control this infection.

Fat Embolism Syndrome Secondary to Injection of Large Amounts of Soft Tissue Filler in the Gluteal Area

There are no reports in the literature of an association between soft tissue filler (STF) injection and fat embolism syndrome (FES). The authors present the case of a 26-year-old woman who was injected in the gluteal area with approximately 200 cc of STF on each side for aesthetic purposes. After this procedure, she presented with the triad of hypoxemia, neurological impairment, and petechiae consistent with the diagnosis of FES. After advanced support measures, she recovered completely. This article reviews the presence of FES after a cosmetic procedure with STF.