Case Histories of Designing Tunnel Linings in Seismic Regions

The original approach to the problem of designing tunnel linings upon the seismic effects consisting in the determination of the most unfavourable stress state in the every lining normal section at different combinations and any directions of long longitudinal and shear waves propagating in the plane of the lining cross-section is described in the paper presented. The analytical methods and corresponding computer programs based on that approach have been developed for the design of tunnel linings of an arbitrary cross-section shape, circular linings inducting the multi-layer ones of the complex of parallel mutually influencing tunnels etc. Two case histories of applying those methods at the design and construction of the railway tunnel and six parallel vertical turbine shafts of the hydro-electric power- station are given

Design of Tunnels Located Near Slopes in Seismic Areas

The original approach to the problem of designing circular tunnel linings located near slopes upon seismic effects consisting in the determination of the most unfavourable stress state in the every lining radial section at different combinations and any directions of long longitudinal and shear waves propagating in the plane of the tunnel cross-section is described in the paper presented. The analytical methods of determining the tunnel lining stress state caused by static loads namely by the rock own weight and the vertical load uniformly distributed on the part of the inclined straight boundary simulating the weight of building or structure on the surface are also described

Evaluation of elastic and adhesive properties of solids by depth-sensing indentation

To describe properly interactions between contacting solids at micro/nanometre scales, one needs to know both adhesive and mechanical properties of the solids. Borodich and Galanov have introduced an effective method (the BG method) for identifying both characteristics from a single experiment on depth-sensing indentation by a spherical indenter using optimal fitting of the experimental data. Unlike traditional indentation techniques involving sharp indenters, the Borodich-Galanov methodology intrinsically takes adhesion into account. It is essentially a non-destructive approach. These features extend the scope of the method to important applications beyond the capabilities of conventional indentation. The scope of the original BG method was limited to the classic JKR and DMT theories. Recently, this restriction has been overcome by introducing the extended BG (eBG) method, where a new objective functional based on the concept of orthogonal distance curve fitting has been introduced. In the present work, questions related to theoretical development of the eBG method are discussed. Using the data for elastic bulk samples, it is shown that the eBG method is at least as good as the original BG method. It is shown that the eBG can be applied to adhesive indentation of coated, multilayered, functionally graded media

Comparative analysis of parameters of pulsed copper vapour laser and known types of technological lasers

In the present paper we present the results of a comparative analysis of pulsed copper vapour lasers with visible emission wavelengths of 510.6 and 578.2 nm and pulse duration of 10-30 ns and known types of technological lasers as well as the prospects for using the copper vapor laser for microprocessing of material

Titanium(III, IV)-Containing Catalytic Systems for Production of Ultrahigh Molecular Weight Polyethylene Nascent Reactor Powders, Suitable for Solventless Processing—Impact of Oxidation States of Transition Metal

Catalytic systems containing TiCl4 or TiCl3, THF, organomagnesium (n-Bu2Mg) and organoaluminum compounds capable of producing ultrahigh molecular weight polyethylene (UHMWPE) were developed. The resulting polymers were characterized by a molecular weight in the range of (1.8–7.8) × 106 Da and desirable morphology, suitable for modern methods of polymer processing—the solvent-free solid-state processing of superhigh-strength (tensile strength up to 2.1 GPa) and high-modulus (elastic modulus up to 125 GPa) oriented films and film tapes. The impacts of a THF additive, the oxidation state of the titanium atom, and the composition and nature of the nontransition organometallic compounds on the formation of catalytic systems for UHMWPE production were evaluated. The results indicate the suitability of individual titanium chloride tetrahydrofuran complex application for the formation of THF-containing catalytic systems. This approach also results in a significant increase in the system catalytic activity and mechanical properties of UHMWPE. The catalysts based on Ti(III) were inferior to systems containing Ti(IV) in productivity but were markedly superior in the mechanical properties of UHMWPE