Browsing by Subject "stress state"

Now showing 1 - 5 of 5

Access status: Open Access ,
Desk study into stress condition of bottom layer of thick coal bed
(Wydawnictwa AGH, 2010) Sidorenko, S. A.; Sidorenko, Andrej Aleksandrovič; Trushko, O.V.
The examined problem is to assess the stress and strain state of the bottom layers in thick regular coal seams. Design diagrams are offered that allow assessment of the impact of primary mining of the 1st layer on the state of the 2nd layer under various geotechnical conditions. A concerns both zones of the active support pressure, the previously mined areas, completely mined sites and zones bordering on the undisturbed coal massif. Regularities are established in changes in the stress state of the bottom layer at the edges of the coal massif and the pillars between the longwall faces. Conclusions are made on the rational location of mining workings at the lower horizons. A significant influence of the neighboring worked out sections is shown on the state of mining workings at the lower horizons.
Access status: Open Access ,
Determination of stress state based on well logging data and laboratory easurements - a CBM well in the southeastern part of the Upper Silesian Coal Basin (Poland)
(Wydawnictwa AGH, 2020) Kępiński, Michał
The main objective of this study is to present calculation methods of horizontal stress profiles, taking into account the stress boundaries model, poro-elastic horizontal strain model and the effective stress ratio approach, using calibration with wellbore failure. The mechanical earth model (MEM) parameters from log measurements and well testing data were estimated for a well located in the southeastern part of the Upper Silesian Coal Basin. Log-derived horizontal stresses of the well are commonly treated as the final product of geomechanical modeling in oil and gas practices. A less popular method for estimating horizontal stresses is based on Kirsch equations juxtaposed with compressional and tensile failure observed on a micro-imager or six-arm caliper. Using this approach, horizontal stresses are determined based on the fact that when hoop stresses exceed the formation’s tensile strength, tensile fractures are created, and when those stresses exceed the compressive strength of the formation, breakouts can be identified. The advantage of this method is that it can be run without in situ stress measurements. The presented workflow is recommended every time there is an image log and dipole sonic measurement in the available dataset, both being necessary to observe the failure zones and MEM.
Access status: Open Access ,
Komputerowa symulacja stanu naprężenia w sąsiedztwie wyrobiska górniczego z uwzględnieniem przepływu gazu
(Wydawnictwa AGH, 2010) Walaszczyk, Jan; Florkowska, Lucyna
One of the natural dangers in coal mining in Poland is methane migration between rock layers. The following paper discusses that issue. The main aim of the paper was to obtain stress distribution around mining excavation area, considering the influence of methane pressure and the process of methane migration through gaps into layers previously without it. In particular, the paper presents a simulation of processes occurring in rock mass during coal exploitation when the migration of methane from lower layers is possible. The issue was solved by numerical modelling, using the Finite Element Method. MES-Abaqus code was used for calculations.
Access status: Open Access ,
Stress state and bearing capacity of shallow tunnel linings undergoing the influence of nearby located buildings
(Wydawnictwa AGH, 2005) Fotieva, Nina; Bulychev, Nikolay; Sammal, Andrey; Deev, Petr
The paper describes a new analytical method of designing shallow tunnel linings of an arbitrary cross-section shape undergoing the influence of buildings both erected nearby the already existing tunnel and constructed before the tunnel driving. The method is based on analytical solutions of the corresponding elasticity theory plane problems for a heavy semi-infinite medium weakened by a supported opening. The approximate technique is proposed for taking the 3-D character of problems into account caused by limited sizes of buildings in the direction along the tunnel axis and by the location of several buildings on some distances between them in this direction. It gives a possibility to determine the stress state and evaluate the lining bearing capacity in different cross-section along the tunnel axis. Example of the design are given.
Access status: Open Access ,
Wpływ temperatury na stan naprężenia i odkształcenia w otoczeniu komory siłowni elektrowni »Porąbka-Żar«
(Wydawnictwa AGH, 2005) Domańska, Danuta; Gruszka, Roman
In the paper preliminary estimation of the stress and strain state around the underground excavation under an influence of temperature is presented. Discussing problem is very important especially for the large chamber (e.g. chamber of the »Porąbka-Żar« power station is described) for which even small fluctuation of temperature can induce big changes of stresses, significant from a static point of view. The analysis presented in the paper is based on measurements that has been executed by Budokop in the excavation. The stress and delamination functions are got from measurements and temperature is taken in the chamber, are interconnected by correlation function. In accordance with expectations coming from the thermoelasticity theory (the paper includes results of approximate calculations), existence of the significant relationship between temperature field and parameters form measurements (i.e. stress and strain in the vicinity of the chamber) is found.