Differences Between Recent Heat Flow Maps of Poland and Deep Thermo-Seismic and Tectonic Age Constraints

Poland is situated in a place of contacts between three continental scale geologic structural units: the Precambrian East European Craton (EEC) to the northeast, the Variscan West European Platform (WEP) terranes to the southwest, and the younger Carpathian Alpine arc in the south. The Trans-European suture zone (TESZ) between the EEC and WEP is a deep-seated discontinuity zone reaching down to a depth of about 200 km. The conjunction of all these continental scale geologic units is reflected in the complex tectonic structure of this area. Apart from the complex seismic structure, this area is also associated with pronounced gravity, magnetic and heat flow anomalies. Significant differences exist between heat flow maps of Poland published in recent works, with values reaching 20 to 30 mWm-2. Examples are differences in heat flow based on models that use well log interpreted mineral and porosity content and assigned world averages of rock and fluid thermal conductivities versus ones based on averaging thermal conductivity values measured using borehole cores only. These differences in heat flow between the methods are discussed in the context of their relationship with tectonic age. Also considered are depth differences between lithosphere – asthenosphere boundary (LAB) derived from thermal model vs those that obey seismological constraints. Higher heat flow estimates reaching up to or more than 100 mWm-2, based on conductivity values derived from well-logs, are found to be quite improbable. This likely reason for overestimate of heat flow is discussed.

THE VARIATION OF THE STRESSES IN THE AREA OF DIAMETER CHANGE IN GAS PIPELINES

<p>The paper presents an analysis of the variation of stresses at a gas pipeline in a geometric discontinuity zone of the diameter. The analysis was performed by assimilating the pipe area with variable diameter with an axially symmetric structure loaded with internal pressure. Stresses were determined using the method of moments, theory for axially symmetrical structures. The analysis was performed according to a set of parameters that define the geometry of a joining between a conical frustum and a cylinder and the loading mode with internal pressure. Efforts and stresses were determined in the meridian direction and in the circumferential direction adjacent coatings combining the two axially symmetries.</p>

Design Optimization of Steel Anchor Beam in Cable-Pylon Composite Anchor Structure

Because the stress concentration usually appears in the plate corner or discontinuity zone, it is necessary to optimize design for local plate of steel anchor beam bearing huge cable force. Based on 3D elaborate finite-element method, the stress distribution of steel anchor beam of cable-pylon composite anchor structure was analyzed. The results showed that the steel anchor beam of cable-pylon composite anchorage structure was safe and reliable, the application of the vertical stiffened plate of the side plate in anchor box and the middle diaphragm efficiently improved the force state of the steel anchor beam, on the other hand the stress conditions of the concrete pylon was more ideal when the steel anchor beam was within the boundary condition of one end of anchor beam fixed and the other end with sliding support.

Shock discontinuity zone effect: the main factor in the explosive decomposition detonation process

A new qualitative conception of the detonation mechanism in condensed explosives has been developed on the basis of experimental and numerical modelling data. According to the conception the mechanism consists of two stages: non-equilibrium and equilibrium. The mechanism regularities are explosive characteristics and they do not depend on explosive charge structure (particle size, nature of filler in the pores, explosive state, liquid or solid, and so on). The tremendous rate of loading inside the detonation wave shock discontinuity zone ( ca. 10 -13 s) is responsible for the origin of the non-equilibrium stage. For this reason, the kinetic part of the shock compression energy is initially absorbed only by the translational degrees of freedom of the explosive molecules. It involves the appearance of extremely high translational temperatures for the polyatomic molecules. In the course of the translational-vibrational relaxation processes (that is, during the first non-equilibrium stage of ca. 10 -10 s time duration) the most rapidly excited vibrational degrees of freedom can accumulate surplus energy, and the corresponding bonds decompose faster than behind the front at the equilibrium stage. In addition to this process, the explosive molecules become electronically excited and thermal ionization becomes possible inside the translational temperature overheat zone. The molecules thermal decomposition as well as their electronic excitation and thermal ionization result in some active particles (radicals, ions) being created. The active particles and excited molecules govern the explosive detonation decomposition process behind the shock front during the second equilibrium stage. The activation energy is usually low, so that during this stage the decomposition proceeds extremely rapidly. Therefore the experimentally observed dependence of the detonation decomposition time for condensed explosives is rather weak.