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For hydraulic tunnel lining detection, a comprehensive wave field method is presented for the detection of hydraulic tunnel lining in this paper, and a 1:1 hydraulic tunnel model is built according to the actual engineering situation. The effects of source, sampling rate, offset and group interval on the detection results are analyzed through experiments, a set of parameters suitable for hydraulic tunnel lining detection is finally derived, which can effectively improve the efficiency and accuracy of lining defect detection in the subsequent work.

Abrasions and pressure ulcers on the oral mucosa are most often caused by excessive pressure or incorrect fitting of the denture. The use of soft relining materials can eliminate pain sensations and improve patient comfort. The main functional feature of soft elastomeric materials is the ability to discharge loads from the tissues of the mucosa. (1) Background: The aim of the work was a comparative laboratory study of ten materials used for the soft lining of acrylic dentures. (2) Methods: There were materials based on acrylates (Vertex Soft, Villacryl Soft, Flexacryl Soft) and silicones (Sofreliner Tough Medium, Sofreliner Tough Medium, Ufi Gel SC, GC Reline Soft, Elite Soft Relining, Molloplast). Laboratory tests include the analysis of the tensile bond strength between the relining material and the acrylic plate of the prosthesis. The tests were conducted taking into account 90-day term aging in the distilled water environment based on the methodology presented in the European Standard ISO 10139-2. (3) Results: After three months of observation, the highest strength of the joint was characterized by Flexacryl Soft acrylic, for which the average value was 2.5 MPa. The lowest average value of 0.89 MPa was recorded for the GC Reline Soft silicone material. Over time, an increase in the value of the strength of the combination of acrylic materials and a decrease in these values in the case of silicone materials was observed. (4) Conclusion: Each of the tested silicone materials showed all three types of damage, from adhesive to mixed to cohesive. All acrylic-based materials showed an adhesive type of failure. Time did not affect the type of destruction.

The main functional feature of elastomeric soft linings materials is the ability to discharge loads in the tissues of the mucosa. As a result, there are fewer injuries to the mucosa and chewing ability increases. In addition, these prostheses are more comfortable in the patient’s opinion. To obtain the equal distribution of forces on the muco-bone basis and to reduce the traumatizing effect of the denture plate for patients using full dentures, soft lining materials can be used. Aim of the study: the aim of the work was a comparative laboratory study of ten materials used for soft lining of acrylic complete dentures. Methodology: Materials based on acrylates (Vertex Soft, Villacryl Soft, Flexacryl Soft) and on silicones (Sofreliner Tough Medium, Sofreliner Tough Medium, Ufi Gel SC, GC Reline Soft, Elite Soft Relining, Molloplast) were compared. Laboratory tests include tests of changes in Shore’a A hardness of soft lining material. The tests were conducted taking into account 90 day term aging in the distilled water environment based on the methodology presented in the European Standard ISO 10139-2. Results: For most silicone materials, only small changes in hardness were found in the range of 0.7 (Ufi Gel SC) to 3.3 (Sofreliner Tough Medium) on the Shore A scale. The exception was GC Reline Soft, for which a marked increase in hardness was noted. All materials based on acrylates were characterized by successive increase in hardness over time. However, in the case of the Vertex Soft material, the increase in hardness was relatively small (5.5 ShA).

In response to the issue of linear cutting of PMMA materials, this study conducted finite element simulations to model and calculate the linear cutting of PMMA targets using shaped charge liners made of copper and lead. Corresponding linear cutting experiments on PMMA targets were also carried out to investigate the influence of shaped charge liner materials on the linear cutting of PMMA. The research results indicate that the fracture of PMMA targets under the action of linear cutting with the cutting cord is mainly caused by jet penetration and spalling. The copper liner cutting cord exhibits superior jet penetration capability, approximately 28% higher than that of the lead liner under 0 mm standoff conditions. Additionally, after the action of the copper liner cutting cord, copper wire residues are produced, whereas no residue issue is observed with the lead liner cutting cord.

This book, MOP 145, provides a comprehensive source of information on the design of flexible, close-fit linings for the renewal or rehabilitation of pipes designed for gravity flow such as sanitary sewers, culverts, and storm sewers.Introductory topics discussed include pipe-soil structure interaction, condition assessment and inspection methods, and lining options, but the main focus is on the thickness design of close-fit flexible liners. This design is based on a closed-form solution, which takes into account both the current shape of the host structure as well as the potential imperfections of the liner (annular gap) and of the host structure (cracks or fractures). The design solutions presented can be used for circular and noncircular geometries such as pipe-arch shapes, egg shapes, elliptical shaped pipes (both horizontal and vertical), box shaped pipes (both rectangular and square), and other, undefined site-specific shapes. MOP 145 will provide guidance to consulting engineers tasked with designing flexible close-fit liners for rehabilitation of existing gravity pipe applications.

The lining cavities in tunnels have strong concealment and pose significant risks, seriously affecting tunnel operational safety. Therefore, it is necessary to develop efficient and high-precision detection techniques for tunnel lining cavities. In this study, concrete slabs with different parameter cavities were selected as the research object, and experiments on remote detection using Laser Doppler Vibrometry were conducted. During the experiments, the vibration parameters of the concrete surface were measured for cavities of varying sizes and depths, filled with different materials, and under different detection distance conditions. The vibration differences between the defective and healthy parts were analyzed using the spatial spectral entropy algorithm. The results showed that for cavities with side lengths of 200mm, depths of 50mm, and filled with hollow wooden boxes, the maximum velocity amplitudes of the surface concrete were 10.68, 3.55, and 4.01 times higher than those of the healthy parts, respectively. Moreover, at the same frequency, larger cavity areas and shallower depths resulted in greater surface vibration amplitudes. The vibration amplitudes of the surface with hollow wooden box filling were higher than those with foam polystyrene board filling. With increasing detection distance, the overall surface vibration velocity of the cavities was higher at a distance of 3 m from the laser probe compared to 5 m, indicating the ability to quantitatively describe the apparent vibration characteristics of concrete cavities under different parameters. This study demonstrates the significant effectiveness of laser Doppler vibrometry in remote detection of lining cavities in tunnels.

Large deformation has always been a focus and difficult issue in the construction of deep-buried tunnels in squeezing rock. Previous studies mainly focused on the large deformation of medium and small span railway/highway tunnels in soft ground. However, there are limited researches on the large deformation control methods for large-span (three-lane) highway tunnels constructed in unfavorable geological environment. Based on the Lianchengshan Tunnel of the Baoji-Hanzhong expressway in Shaanxi Province, China, this paper studied the deformation behaviors and mechanical mechanisms of a large-span tunnel excavated in chlorite schist formation with single primary lining method and double primary lining method by in-situ test and numerical simulation. The achieved results indicate that the double primary lining method is much more effective than that of the single primary lining method in restraining the deformation of surrounding rock, and the maximum vertical displacement and horizontal convergence are reduced by 67% and 66%, respectively. The support method of double HK200b-type steel sets combined with large-diameter foot reinforcement bolt (FRB) and deep invert could effectively control the large deformation of the case tunnel, which effectively avoided the supporting structure failure, repeated clearance invasion and multiple reshaping work caused by the single primary lining method and conformed to the energy-saving construction concept of “no clearance interfering, no support reshaping” of tunnels in squeezing ground. Simulation analysis of surrounding rock deformation, supporting structure stress and plastic zone distribution was performed to evaluate the support effect of the two deformation-controlled methods. Finally, the deformation and stress characteristic curves of rock-support of the two deformation-controlled methods were established, which revealed the supporting mechanism of double primary linings for large-span tunnels in chlorite schist. The research results can provide a theoretical basis and practical reference for the large-deformation control of similar large-span tunnels in squeezing rock.

For tunnels excavated in soft layered rock strata, the secondary lining is susceptible to asymmetrical pressure and substantial concrete cracking. To solve this problem, a supporting system that combines a secondary lining with a highly deformable layer is proposed. First, field investigations were conducted to reveal the mechanical behaviors of the secondary lining of two typical tunnels situated in phyllite formation in China. Then, similarity model tests were used to analyze the mechanical responses of the secondary lining in layered rock stratum with different inclination angles. Finally, numerical simulation was adopted to systemically investigate the yielding mechanism of yielding layer in different cases. The results show that: (1) The distribution of inner force and deformation of lining is non-uniform due to the anisotropy of rock mass and geo-stress field, with the positive bending moment and larger axial force appearing mainly in the region where the tangent of the tunnel contour is parallel or vertical to the weak planes, respectively. (2) The existence of yielding layer has no influence on the distributed feature of inner force and displacement around tunnel perimeter, while it can significantly lower the magnitude of inner force and displacement of the lining. (3) The distinctly compressive zones of yielding layer coincide with the zones of positive bending moment, and the line connecting the central points of the evidently compressive zones on both sides will deflect towards the direction of minor principal stress to a certain extent. (4) The inner force and deformation of lining increase with the increase in the strength or decrease in the thickness of yielding layer, and this changing trend is related to the different supporting curves for linings with yielding layer of different strength and thickness.

This research compared the characteristics of new brake linings with brake linings after 100 flight hours. The methods used were chemical composition, hardness, and wear tests. New Cleveland type 66-033 brake linings consisted of 77.489% Cu, 15.81% Fe, 6.047% Si, 0.305% Mn, and 0.34% Ni. After 100 flight hours, the composition changed to 95.9% Fe, 0.8% Cu, 0.235% Si, 0.468% Mn, and Al, Mo, Cr, and C were detected due to tribochemical reactions and material transfer from the rotor. The hardness increased from 79.65 HB to 207 HB, indicating that used brake linings were harder due to overheating, densification, resin combustion, tribofilm formation, and durable phase oxidation. In contrast, new brake linings were softer because they still contained resin, pores, and unmodified structures. The wear rate of new brake linings was higher than that of 100 flight hours brake linings. This is due to the soft material, easily degradable resin, and the lack of a protective tribofilm, resulting in faster wear. New brake linings were tested for an intact and uniform microstructure, while the microstructure test results of 100 flight hours brake linings exhibited wear, microcracking, and uneven particles.

Sustainable development involves the usage of alternative sustainable materials in order to sustain the excessive depletion of natural resources. Plant fibers, as a “green” material, are progressively gaining the attention of various researchers in the field of construction for their potential use in composites for stepping towards sustainable development. This study aims to provide a scientometric review of the summarized background of plant fibers and their applications as construction and building materials. Studies from the past two decades are summarized. Quantitative assessment of research progress is made by using connections and maps between bibliometric data that are compiled for the analysis of plant fibers using Scopus. Data refinement techniques are also used. Plant fibers are potentially used to enhance the mechanical properties of a composite. It is revealed from the literature that plant-fiber-reinforced composites have comparable properties in comparison to composites reinforced with artificial/steel fibers for civil engineering applications, such as construction materials, bridge piers, canal linings, soil reinforcement, pavements, acoustic treatment, insulation materials, etc. However, the biodegradable nature of plant fibers is still a hindrance to their application as a structural material. For this purpose, different surface and chemical treatment methods have been proposed in past studies to improve their durability. It can be surmised from the gathered data that the compressive and flexural strengths of plant-fiber-reinforced cementitious composites are increased by up to 43% and 67%, respectively, with respect to a reference composite. In the literature, alkaline treatment has been reported as an effective and economical method for treating plant fibers. Environmental degradation due to excessive consumption of natural resources and fossil fuels for the construction industry, along with the burning of waste plant fibers, can be reduced by incorporating said fibers in cementitious composites to reduce landfill pollution and, ultimately, achieve sustainable development.