Tunnell boring

OBJECTIVES: This study aimed to assess the exposure to a selection of aerosols and gases in the work environment for workers performing tunnel construction using tunnel boring machines (TBMs), to identify determinants of exposure based on the information available and to calculate robust estimates of exposure using a statistical model. The focus was particulate matter (PM) and respirable crystalline silica (RCS). In addition, concentrations of nitrogen dioxide (NO2), elemental carbon (EC), and oil mist were assessed...

The codling moth Cydia pomonella (Lepidoptera: Tortricidae) is a major invasive pest of pome fruits and walnuts worldwide. Lambda-cyhalothrin (LCT) and abamectin (AM) have been frequently used in C. pomonella control, but control of this pest is very difficult because shortly after hatching, larvae of this insect bore tunnels and hide inside host plant fruit. In this study, a simulated field spray bioassay method was developed against neonate larvae of C. pomonella and concentration-response bioassays were conducted to evaluate the susceptibility of the neonate larvae to LCT and AM...

Tunnel boring machine (TBM) materials are usually crushed powder obtained during tunnel excavations for subways and transportation networks. Huge quantities of crushed rock powder are generally treated as waste. This study is aimed at assessing proposed mixtures of TBM and granular material for use in construction. This approach will help in a greener environment and reduce the need for crushed aggregates used in sub-base and subgrade layers of pavements. Assessment is executed using dynamic and static strength tests, including the modulus of resilience and the California bearing ratio (CBR)...

A new type of Filament Wound Profiles (FWPs) have been applied to strengthen the deformed stagger-jointed segmental tunnel linings, and a full-scale test was carried out on the ultimate bearing capacity of the linings that are strengthened by the new FWPs. The failure phenomena and the main experimental results were obtained, including the load-displacement curve, strain and bond failure. The internal forces of the FWPs in the strengthened lining were calculated and discussed. The failure chain and weak sections of the strengthened lining were discussed...

In order to improve the construction method of highway tunnel fault, improve the excavation level, improve the construction efficiency, reduce the project cost, and shorten the construction period, so as to find a specific road, this paper puts forward the research method of tunnel stability analysis and construction parameter optimization in the fault fracture zone. First, this paper analyzes the specific geographical and geological environment of the construction site. Second, this paper compares and analyzes the effects of the drilling and blasting method and full-face tunnel boring machine (TBM) in construction and further analyzes the surrounding rock deformation, over excavation, and under excavation, as well as the range of loose circles when the surrounding rock is stable...

Carrying out status monitoring and fault-diagnosis research on cutter-wear status is of great significance for real-time understanding of the health status of Tunnel Boring Machine (TBM) equipment and reducing downtime losses. In this work, we proposed a new method to diagnose the abnormal wear state of the disc cutter by using brain-like artificial intelligence to process and analyze the vibration signal in the dynamic contact between the disc cutter and the rock. This method is mainly aimed at realizing the diagnosis and identification of the abnormal wear state of the cutter, and is not aimed at the accurate measurement of the wear amount...

As a vector of pine wood nematode disease, Monochamus alternatus is wood-boring, cryptic, and extremely difficult to control-features that have made them a disastrous problem. In this study, we present a method of scanning the galleries of Monochamus alternatus using CT (computed tomography) technology to obtain their systematic structure via 3D (three-dimensional) reconstruction, so as to clarify the gallery types and their structural parameters. TLC (thin-layer chromatography) scanning on wood segments damaged by M...

The EFSA Panel on Plant Health performed a pest categorisation of Platypus apicalis (Coleoptera: Curculionidae: Platypodinae), an ambrosia beetle, also known as a pinhole borer, for the EU territory. P. apicalis is a polyphagous pest native to New Zealand. The majority of its life cycle is spent inside tree wood, but it does not directly feed on plant tissue, instead larvae and adults feed on a symbiotic fungus ( Sporothrix nothofagi which is pathogenic to Nothofagus spp.) vectored by adults and introduced when they bore tunnels into the host...

Autonomous navigation in mining tunnels is challenging due to the lack of satellite positioning signals and visible natural landmarks that could be exploited by ranging systems. Solutions requiring stable power feeds for locating beacons and transmitters are not accepted because of accidental damage risks and safety requirements. Hence, this work presents an autonomous navigation approach based on artificial passive landmarks, whose geometry has been optimized in order to ensure drift-free localization of mobile units typically equipped with lidar scanners...

BACKGROUND: The ideal central venous catheter (CVC) tip position placement is controversial, and CVCs do not remain in a fixed position after placement. This study evaluates both patient and procedural factors which may influence CVC tip migration and subsequent catheter dysfunction. MATERIALS AND METHODS: This study evaluates CVC placements at a single institution. Patient age, gender, body mass index (BMI), catheter laterality, CVC type and indication for central venous access were recorded...

This work aims to investigate and analyse the mechanism of rock failure under high-voltage electropulses in order to evaluate and increase the efficiency of high-voltage pulse technology in geological well drilling, tunnel boring, and other geotechnical engineering applications. To this end, this paper discusses the equivalent circuit of electric pulse rock breaking, the model of shock wave in electro channel plasma, and, particularly, the model of rock failure in order to disclose the rock failure process when exposed to high-voltage electropulse...

INTRODUCTION: A Vereos PET/CT device was adapted to be compatible with the experimentation in large animals within BSL-3 environment. The aim of this study was to investigate the impact of this modification on the performance according to NEMA NU2-2012 standard. METHODS: Spatial resolution, sensitivity, count rate performance, accuracies of corrections and image quality were assessed using the NEMA NU2-2012 standards before and after installation of a transparent poly-methyl methacrylate tube of 8 mm thickness, 680 mm diameter and 2800 mm long inside the tunnel of the system...

Placement of image-guided tunneled and non-tunneled large-bore central venous catheters (CVCs) are common procedures in interventional radiology. Although leukopenia and/or thrombocytopenia are common at the time of placement, the roles these factors may have in subsequent catheter-related infection have yet to be investigated. A single-institution retrospective review was performed in patients who underwent CVC placement in interventional radiology between 11/2018-6/2019. The electronic medical record was used to obtain demographics, procedure details, pre-placement laboratory values, and the subsequent 90-day follow-up...

Asian corn borer, Ostrinia furnacalis (Guenée), is an important insect pest of maize throughout most of Asia. The rind of a maize stalk is a key barrier against corn borer larvae boring into the plant. There is a need to better understand the relationship between stalk strength and O. furnacalis larval injury, particularly for elite maize genotypes. To determine whether stalk strength is involved in maize resistance to O. furnacalis larval injury, 39 maize lines were evaluated in 2012 and 2013. Rind penetration strength (RPS) was measured at tassel (VT) and milk (R3) stages as a possible stalk resistance trait for O...

In order to evaluate the potential impact of the shallow tunnel excavation by a tunnel boring machine (TBM) in urban areas, the authors present original in-situ measurements of vibrations inside the TBM and simultaneously on the surface. Four experimental campaigns were carried out on French tunnelling or micro-tunnelling projects, whose geotechnical contexts vary from hard rock to clayey sands. Each campaign is divided into two steps: (i) before excavation, measurements on the surface under mechanic ambient noise, and (ii) during excavation, measurements on the surface and inside the TBM...

We investigated the geometric evolution of mesoscopic mechanical structures in rocks during the rock fragmentation process induced by tunnel boring machine cutters. Numerical models were built using a grain-based discrete element method to accurately represent the mesoscopic structures and macroscopic mechanical behaviours of rocks, and the relationship between the mesoscopic evolution and the macroscopic response of rock was determined. The major results are as follows. First, the crushing and re-compaction of the grains were found to mainly occur in the thin crushed zone immediately beneath the cutter tip...

Rock mass condition assessment during tunnel excavation is a critical step for the intelligent control of tunnel boring machine (TBM). To address this and achieve automatic detection, a visual assessment system is installed to the TBM and a lager in-situ rock mass image dataset is collected from the water conveyance channel project. The rock mass condition assessment task is transformed into a fine-grain classification task. To fulfill the task, a self-convolution based attention fusion network (SAFN) is designed in this paper...

BACKGROUND: Critically ill patients with coronavirus disease 2019 (COVID-19) and kidney dysfunction often require tunneled hemodialysis catheter (TDC) placement for kidney replacement therapy, typically under fluoroscopic guidance to minimize catheter-related complications. This entails transportation of patients outside the intensive care unit to a fluoroscopy suite, which may potentially expose many healthcare providers to COVID-19. One potential strategy to mitigate the risk of viral transmission is to insert TDCs at the bedside, using ultrasound and anatomic landmarks only, without fluoroscopic guidance...

The EFSA Panel on Plant Health performed a pest categorisation of the snout moth Leucinodes pseudorbonalis Mally, Korycinska, Agassiz, Hall, Hodgetts & Nuss (Lepidoptera: Crambidae), for the territory of the EU. This species is not included in the EU Commission Implementing Regulation 2019/2072. This oligophagous species, which feeds on fruit and leaves of Solanum aethiopicum (Ethiopian eggplant) and S .  melongena (eggplant), is known to occur in sub-Saharan Africa (Angola, Liberia, Senegal, Uganda)...

Infestation by a moth woodborer species is causing mortality of Sonneratia alba Sm. mangrove by tunneling through the inner bark, cambium and conductive tissue. Infestation leads to death of some infested branches, whereas in other cases infested branches have been observed to recover from infestation. We have used Fourier transform infrared spectroscopy (FTIR) to investigate the differences in macromolecule (polysaccharide and lignin) content present in branches that died (D) of the infestation, those that recovered (R) from the infestation and control branches (C) that were not subject to any infestation...