• Injection in trenchless technologies – influence of grout parameters on the injection radius
  Borehole grouting is one of the fundamental methods of sealing and reinforcing the ground in trenchless technologies. The key design parameter of grouting works is the grouting radius, i.e. the extent of grout propagation within the ground, which determines borehole spacing, grout take and sealing efficiency. This paper presents the physical fundamentals of permeation (classical) grouting and two analytical models of the grouting radius: the Maag model, applicable to grouting through an open-ended pipe (spherical source), and the Tafeli model for perforated pipes (cylindrical source). It is shown that the Maag model yields a non-linear dependence of radius on pressure (R ∝ p1/3) with a diminishing relative increase, whereas the Tafeli model gives a square-root increase (R ∝ p1/2) and larger predicted extents. Analysis of the influence of grout and ground parameters shows that process efficiency is governed primarily by the coefficient of permeability (kf) and the grout viscosity: low-permeability soils considerably restrict the grouting radius, while lowering the grout viscosity substantially increases its penetration. Since excessive injection pressure leads to hydraulic fracturing and disturbance of the soil structure, a more effective and safer solution is the optimization of the rheological properties of the grout rather than increasing the injection pressure... dalej
• Copper tubing connection processes by soldering in gas installations. Technical and legal aspects
  This article outlines the rationale for constructing gas installations from copper and justifies the need for brazing in gas installations. Furthermore, the brazing process is explained in detail, taking into account the phenomena of capillary action and diffusion. Finally, it proposes amendments to the Regulation of the Minister of Infrastructure on the technical requirements for buildings, specifying the parameters of brazing... dalej

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