Wyniki wyszukiwania - BazTech

1

Tectonic strain in salt rock mass based on measurements

Szczerbowski Zbigniew, Niedbalski Zbigniew, Bednarek Łukasz

Geology, Geophysics and Environment

|

2023

|

Vol. 49, no. 2

157--173

EN

The measurement method with the application of an extensometer for the detection of the manifestation of tectonic strain is presented in this paper. The instrument is operated in underground construction for engineering purposes, and the authors applied it in a deeply placed underground old mine gallery in the Bochnia Salt Mine, just at the tectonic boundary of the Outer Carpathians which is commonly considered to be a tectonically active zone. The presented study is characterized by two basic features. The first is the placement of the measurements deep in an old mine which is an environment free of atmospheric factors disturbing the detection of a tectonic signal. The second is a combination of routine measurements carried out for engineering purposes and research measurements enabling the extension of the observation of displacements in the space outside underground workings, inside the rock mass that has been penetrated by extensometer probes. The extensometric measurements have been made using three 7-meter long sections. The results showed the differentiation in the displacement rates of points placed in the side walls: in the southern profile, the annual displacements are approximately 1.5 mm and in the northern one – approximately 1 mm. The combined result corresponds to the amount of the annual convergence value which has been determined by the classical surveys in the excavation where extensometric measurements have been made. What is more, the ongoing displacements in the southern side wall involve the entire part of the rock mass which is penetrated by an extensometric probe, but the displacements in the northern side are only observed in the first 2 m of the penetrated part of the rock mass. This differentiation is interpreted by the authors as being the result of tectonic strain acting from the south exerted by the Carpathians.

2

An assessment of how penetration curve adjustment affects the California bearing ratio (CBR)

Bednarek Łukasz

Studia Geotechnica et Mechanica

|

2021

|

Vol. 43, nr 4

323--336

EN

With the rapidly developing road transport, there is a demand for new roads to be constructed and for the existing ones to be repaired or extended. The base of any road is its foundation, usually made of crushed or uncrushed aggregate. To be used for road foundation purposes, a material needs to meet many requirements, as imposed by relevant standards. One of the basic tests to assess the suitability of an aggregate is to determine its California bearing ratio (CBR). This paper presents the results of CBR tests for mixed aggregate with the grading of 0–31.5 and 0–63 mm. Detailed assessments were carried out for penetration curves, which in many cases need to be adjusted to meet industry standards. The adjustment of plunger penetration curves in aggregate samples causes CBR to increase compared to the original curves.

3

Automatyczny system monitoringu stateczności wyrobisk korytarzowych

Małkowski Piotr, Niedbalski Zbigniew, Bednarek Łukasz, Pytlik Marian, Frymarkiewicz Arkadiusz, Filipowicz Krzysztof

Przegląd Górniczy

|

2021

|

T. 77, nr 7-9

9--23

PL

Zapewnienie stateczności wyrobisk jest kluczową sprawą dla prawidłowego funkcjonowania kopalni podziemnej. Dla danych warunków geologiczno-górniczych, w celu zachowania wymaganych gabarytów wyrobiska, dobierany jest odpowiedni schemat obudowy. Po wykonaniu projektu taki powinien jednak zostać zweryfikowany na podstawie pomiarów dołowych. Badania te powinny dotyczyć zarówno górotworu, jak i obudowy i stać się następnie podstawą kalibracji przyjętych modeli obliczeniowych oraz parametrów warunku wytrzymałościowego dla skał. W artykule przedstawiono opracowany system zintegrowanego automatycznego monitoringu wyrobiska przyścianowego oraz podano przykładowe wyniki pomiarów. Urządzenia elektroniczne zabudowane w wyrobisku pozwoliły na pomiar rozwarstwień stropu, obciążenie obudowy podporowej, obciążenie obudowy kotwiowej oraz na pomiar zmian naprężeń w górotworze. Ponieważ wyrobisko było utrzymywane w części przyzrobowej, wykonywano także pomiar obciążeń kasztów. Wszystkie urządzenia podpięte były do rejestratorów, które mogły gromadzić bezobsługowo dane przez dłuższy okres czasu. Uzyskane doświadczenia pokazują, że opracowany system można zastosować w innych wyrobiskach, gdzie dostęp jest utrudniony lub np. drążony w samodzielnej obudowie kotwowej.

EN

Ensuring mining workings stability is the key problem for the proper underground mine activity. The support passport of any working is designed for the common mining and geological conditions and should guarantee the required working dimensions for the specific range of time. However, after the support execution, the project should be then verified by the underground measurements. These measurements should concern both rock mass and support control and they should serve as the calibration of the rock mass model assumptions and the failure criterion. The integrated automatic monitoring system for the gate stability control and exemplary results are presented in the paper. Electronic devices installed in the working allowed to measure the roof rocks separation, a load on support frame, a load along the rock bolt and a change of stress in the rock mass. As the gate was maintained behind the longwall face the load on wooden box cribs was controlled as well. All the devices were connected to dataloggers, which could collected data unattended for a long time. The experience gained shows, that designed system can be applied in other underground workings, especially there, where the access is limited or e.g. where only roofbolting is applied.

4

Automatic Monitoring System Designed for Controlling the Stability of Underground Excavation

Małkowski Piotr, Niedbalski Zbigniew, Bednarek Łukasz

Inżynieria Mineralna

|

2021

|

no. 2

15--29

EN

Ensuring the stability of mining excavations is a crucial aspect of underground mining. For this purpose, appropriate shapes, dimensions, and support of workings are designed for the given mining and geological conditions. However, for the proper assessment of the adequacy of the used technical solutions, and the calibration of the models used in the support design, it is necessary to monitor the behavior of the excavation. It should apply to the rock mass and the support. The paper presents the automatic system designed for underground workings monitoring, and the example of its use in the heading. Electronic devices that measure the rock mass movements in the roof, the load on the standing support, and on bolts, the stress in the rock mass, are connected to the datalogger and can collect data for a long of time without any maintenance, also in hard-to-reach places. This feature enables the system to be widely used, in particular, in excavations in the vicinity of exploitation, goafs, or in the area of a liquidated exploitation field.

5

Statistical analysis of mechanical properties on the example of aggregates of Carpathian sandstones

Hydzik-Wiśniewska Joanna, Bednarek Łukasz

Studia Geotechnica et Mechanica

|

2020

|

Vol. 42, nr 4

366-375

EN

The constantly growing, broadly understood, construction industry requires the use of a large amount of aggregates. The construction of roads, motorways, railway lines and hydrotechnical structures requires the use of aggregates of high quality, which is primarily determined by mechanical properties. The basic parameters describing mechanical properties of aggregates are the Los Angeles (LA) fragmentation resistance coefficient and the Micro-Deval (MDE) abrasion resistance coefficient. The LA and MDE coefficients depend mainly on the type of rock and its physical and mechanical properties. This has been thoroughly researched and documented as evidenced by the abundant literature in the field. However, the correlation between LA and MDE coefficients still gives rise to extensive discussions and some concerns. A number of publications demonstrate dependencies for various types of aggregates. Therefore, research was undertaken to present statistical analysis for one type of aggregate and one geological area. This article presents the results of the fragmentation resistance test in the Los Angeles drum and the abrasion resistance test in the Micro-Deval drum of aggregates from Carpathian sandstone deposits. Aggregate samples were divided into three groups according to the location of the deposits and the tectonic unit from which they originated. The obtained results were subjected to static analysis to fit the best mathematical function describing the relationship between the two parameters.

6

The effect of temperature on the mechanical properties and workability of rock salt

Małkowski Piotr, Bednarek Łukasz, Kotwica Krzysztof, Stopka Grzegorz

New Trends in Production Engineering

|

2019

|

Vol. 2, Iss. 1

384--393

EN

Underground salt mining accounts for about 16 percent of the total salt production worldwide. When excavating salt rock, the cutters of the road header come into contact with the rock. This produces friction and, consequently, a rise in temperature. Generally, as temperature increases, salt gradually loses its plasticity. The extent of these alterations depends on the presence of other minerals in the rock. This paper presents the results of laboratory tests on regularly shaped samples of salt. An analysis was performed of the results of compressive, tensile and induced-shear strength, and of Young's modulus, Poisson's ratio, cuttability index and side chipping angle. The testing was conducted on samples with a temperature of about 20°C and samples heated to 50°C and 80°C. The tests showed that as temperature increased, so did compressive and tensile strength, and longitudinal and transverse strain of salt. The temperature increase caused, however, a decrease in shear strength. The cuttability index and the side chipping angle also decreased when the heated samples were being cut. The percentage changes in the parameters within the 60-degree temperature range were as high as several dozen percent.