Expansive Rock Research Articles

A new design of support for burst-prone rock mass in underground ore mining

The article presents the basic methods of strengthening room and roadway excavations in underground ore mining. In particular, it was pointed out that the mining support is very often exposed to additional dynamic loads resulting from the mining of the deposit by means of explosives (slight) as well as from the load arising from rock mass tremors. In the article a new design of arch yielding support adapted to dynamic loads, which can be used in long-term access excavations was proposed. For this case, an exemplary spring deflection, which is located in the support foot cylinder, based on the principle of work and energy was calculated. In the case of exploitation room excavations, laboratory tensile tests of the long expansion rock bolt support, which were carried out in the rock bolting laboratory at the Department of Underground Mining AGH were presented. Load-displacement characteristics for long expansion rock bolt support with a particular indication of the elastic and plastic range were presented. In the summary, it was concluded that with the increase in the depth of exploitation, safe and efficient mining will be possible only due to the use of a support with appropriate yielding.

Application of Long Expansion Rock Bolt Support in the Underground Mines of Legnica–Głogów Copper District

Abstract In the underground mines of the Legnica–Głogów Copper District (LGOM) the main way to protect the room excavation is the use of a rock bolt support. For many years, it has proven to be an efficient security measure in excavations which met all safety standards and requirements. The article presents the consumption of the rock bolt support in the Mining Department “Polkowice–Sieroszowice” in the years 2010–2015 as well as the number of bolt supports that were used to secure the excavations. In addition, it shows the percentage of bolt supports that were used to conduct rebuilding work and cover the surface of exposed roofs. One of the factors contributing to the loss of the functionality of bolt supports is corrosion whose occurrence may lead directly to a reduction in the diameter of rock bolt support parts, in particular rods, bearing plates and nuts. The phenomenon of the corrosion of the bolt support and its elements in underground mining is an extremely common phenomenon due to the favorable conditions for its development in mines, namely high temperature and humidity, as well as the presence of highly aggressive water. This involves primarily a decrease in the capacity of bolt support construction, which entails the need for its strengthening, and often the need to perform the reconstruction of the excavation. The article presents an alternative for steel bearing plates, namely plates made using the spatial 3D printing technology. Prototype bearing plates were printed on a 3D printer Formiga P100 using the “Precymit” material. The used printing technology was SLS (Selective Laser Sintering), which is one of the most widely used technologies among all the methods of 3D printing for the short series production of the technical parts of the final product. The article presents the stress–strain characteristic of the long expansion connected rock bolt support OB25 with a length of 3.65 m. A rock bolt support longer than 2.6 m is an additional bolt support in excavations, and it is increasingly frequently used to reinforce roofs and in rebuilding the underground mines of KGHM Polish Copper S.A. In order to conduct the laboratory tests that are most suitable for the mine conditions, and yet are carried out on a laboratory test facility, the Authors used a steel cylinder with an external diameter of 102 mm and a length of 600 mm, which was filled with a core of rock (dolomite) from the roofs of the mine workings. In addition the maximum load that took over the bolt support made of rods and connected with sleeves was determined. For the initial tension, the elastic and plastic range of the maximal displacements, which were measured by the rope encoder, were determined. The statical tests of the expansion rock bolt support were carried out at the laboratory of the Department of Underground Mining in simulated mine conditions. The test facility enables the study of the long bolt rods on a geometric scale of 1:1 for the different ways of fixing. The aim of the laboratory research was to obtain the stress–strain characteristics, of the long expansion rock bolt support with a steel bearing plate and a plate printed on a 3D printer.

Assessing the Influence of Humidity on the Stability of Expansive Soil Rock Surrounding Tunnels

Assessing the Influence of Humidity on the Stability of Expansive Soil Rock Surrounding Tunnels

Dynamic expansion rock bolt for rapid installing in rocks

Rock bolts are used as permanent and temporary support systems in tunneling and mining operations. A dynamic-expansion rock bolt system that can be installed rapidly in a drilled hole is introduced in this article. The dynamic-expansion rock bolt system consists of a star-shaped steel tube and an ignition system with a dynamic expansion agent in the steel tube of the rock bolt. After the ignition of the dynamic agent in the tube, the star-shaped steel tube expands dynamically as a result of gas production by the dynamic agent. This expansion leads to frictional mounting of the tube in a drilled hole. Laboratory-scale pull-out tests of the rock bolt, installed in a thick steel tube, were performed to investigate the friction behavior between the steel tube and the smooth wall of a drilled hole. These tests revealed that the ultimate pull-out load reached approximately 6 kN and that a long displacement subsequently occurred. Field-scale tests for two prototype rock bolts were performed to evaluate the pull-out load-bearing capacity of the rock bolt. The welded areas of the two tube bolts were broken when the pull-out loads reached approximately 114 and 91 kN.

Laboratory Method for Evaluating the Characteristics of Expansion Rock Bolts Subjected to Axial Tension / Laboratoryjna Metoda Badania Charakterystyk Kotew Rozprężnych Poddanych Rozciąganiu Osiowemu

Abstract Rock bolts have long been used in Poland, above all in the ore mining. Worldwide experience (Australia, Chile, Canada, South Africa, Sweden, and USA) provides evidence of rock bolt supports being used for loads under both static and dynamic conditions. There are new construction designs dedicated to the more extreme operating conditions, particularly in mining but also in tunneling. Appreciating the role and significance of the rock bolt support and its use in Polish conditions amounting to millions of units per year, this article describes a new laboratory test facility which enables rock bolt testing under static load conditions. Measuring equipment used as well as the possibilities of the test facility were characterized. Tests were conducted on expansion rock bolt supports installed inside a block simulating rock mass with compression strength of 80 MPa, which was loaded statically as determined by taking account of the load in order to maintain the desired axial tension, which was statically burdened in accordance with determined program load taking into consideration the maintenance of set axial tension strength at specified time intervals until capacity was exceeded. As an experiment the stress-strain characteristics of the rock bolt support were removed showing detailed dependence between its geometrical parameters as well as actual rock bolt deformation and its percentage share in total displacement and deformation resulting from the deformation of the bolt support elements (washer, thread). Two characteristic exchange parts with varying intensity of deformation /displacement per unit were highlighted with an increase in axial force static rock bolt supports installed in the rock mass.

Study on the Infiltration Rule of Expansive Rock Canal Slope

In order to find out the infiltration rule of expansive rock canal slope, take the expansive rock in south-to-north water diversion project as sample. First, soil-water characteristic curve of expansive rock test was carried out. It predicts the unsaturated infiltration coefficient. Then, based on the test result and the saturated-unsaturated seepage theory, the varying law of seepage field under different rainfall intensity was studied. The results show that when the rainfall intensity is less than the slope material saturated permeability coefficient, with the increase of slope rainfall duration, the underground water level rises gradually, but the increase is very small. Meanwhile, there isn't saturation zone on the surface of the slope. When the rainfall intensity is greater than or equal to the slope material saturated permeability coefficient, after one day's continuous rainfall, saturation zone appears in the slope surface. After 5 days' continuous rainfall, saturation zone appears in the middle of the slope (elevation: 89m). After 12 days' continuous rainfall, the underground water level arrives at the slope toe. So, in order to prevent slope sliding under the rainfall infiltration condition, both the slope toe and the middle of the slope should all be given enough attention, and it is not only necessary but also essential to take drainage measures in the relevant position in advance.

Test Research on Engineering Property of Expansive Rocks of Anyang Test Zone in Middle Route of South-North Water Transfer Project

Test samples are selected in different depths of Pile No.1370 at Anyang test zone in Middle Route of South-North water transfer project. Through a series of experiment, the physical properties, mineral components and properties of mechanics, permeability and swelling-shrinking of expansive rock are well studied. The results show that hydrophilic mineral component of the expansive rock in different depths differ remarkably. To the same kind of expansive rock samples with the same dry density, cohesion and friction angles are negative linear correlation with moisture content respectively and cohesion is more sensitive to moisture content. With the same initial moisture content, the logarithm of saturated permeability coefficients of expansive rock samples are linear correlation with their dry densities. The initial moisture content has a much larger effect on maximum swelling ratio than shrinkage, thus the process of swelling-shrinking is not reversible. The results can supply scientific references for the South-North water transfer project.

Study on the Treatment Measures of Expansive Rock Slope

Expansive rock is a special gneis with problems, spread widely in our country. Currently the government is carrying on constructions of infrastructure such as railways and transfer project of south water to the north. Such defective rock can disturb the construction process: due to its extreme sensitivity to temperature, humidity and stress field, swell rock has big potential harm to the project construction; a slight change in external factors could bring great damage to the project construction. Based on the analysis of the project characteristics, The thesis gives the treatment measures of expansive rock slope. The study is quite meaningful for the stability of the expansive rock slope.

Expansive Rock Deep Cutting Slope Treated by Flexible Supporting Technology for Beijing Western Sixth Ring Highway

The landslides of expansive rock cutting slope was the most serious and difficultly treating engineering problem for highway construction. The K9+600-K10+800 section of Beijing Western Sixth Ring highway was an expansive rock deep cutting slope, the problem of which was firstly encountered for Beijing highway construction. In this paper, the causes and characteristics of expansive rock slope failure were analyzed based on the engineering geology and rock properties of this section. In addition, the geogrid reinforced flexible supporting treatment measure was presented and its design scheme and construction approach were introduced. This method with the characteristics of “preserving moisture and antiseepage” and “softness and hardness” could resolve this kind of expansive rock slope problem effectively and economically.

Constitutive Equation of Expansion Rock under Humidity Field

The weight and length, width and height of three directions of cuboids’ type calcareous mudstone after infiltrated with water in different period of time were measured by using electronic balance and vernier caliper. The results show that the calcareous mudstone expansion strain is proportional to volume and mass water content. Mchanical properties of calcareous mudstone were studied by uniaxial compression experiments of calcareous mudstone with different water content which carried out by using microcomputer controlled electro-hydraulic servo compression testing machine control system of YAW series. It is concluded from experiment result that calcareous mudstone is brittleness with low water content but when water content reaches saturation, calcareous mudstone presents plastic features. Based on the results above, the constitutive equation of rock considering humidity field is derived which provides important guiding significance to engineering practice.

Alkali reactivity of dolomitic rocks from Argentina

This paper describes a series of studies conducted with the aim of evaluating the deleterious alkali susceptibility of carbonate rocks used in portland cement concrete manufacture. These studies have shown the existence of argillaceous dolomitic rocks in our country which can react with the alkalis present in concrete causing an alkali-carbonate reaction. The petrographic characteristics of the samples studied are, however, different from those described in the literature for typical carbonate expansive rocks. Experimental results indicate that the expansion mechanisms involved in this reaction, not fully understood yet, are different from those of the ASR (absence of gels, no pessimum phenomenon, increase in expansion with the increase in the maximum aggregate size, ineffectiveness of widely known chemical and pozzolan inhibitors, etc.). This paper summarizes the results obtained by using current characterization techniques (ASTM C 586, ASTM C 227, NBRI, CSA A23.2–14A, etc.) as well as X-ray diffraction analysis, optical microscopy and SEM microstructural observations.

Geology of Greater Kansas City, Missouri and Kansas, United States of America

Metropolitan Kansas City, straddling the Missouri-Kansas state line, has experienced rapid growth in recent decades. Settled in the early 1800's, to serve as the starting point for many of the famous western trails, Kansas City still serves as the major center for marketing and distribution of farm products and agriculture-related businesses. Endowed with favorable geology, Kansas City has abundant supply of good quality limestone and other construction materials to sustain its growth through the years ahead and into the next century. Pennsylvanian sedimentary rocks crop out in the area imparting it an aesthetically-pleasing hills and valley configuration. Desirable engineering properties of limestone and favorable geologic structure have aided in extensive development of underground space in the area. With 1.8 million m2 of developed space, Kansas City has the distinction of being the world leader in human use and occupancy of underground space. A detailed discussion of the history of underground space development, associated problems, and future prospects is presented in the paper. Geologic constraints of concern in the area include flooding, ground subsidence, expansive rocks and soils, mass movements and radon gas hazards. Completion of major dams and other flood protection works on the Missouri and Kansas rivers have nearly eliminated the flooding on the main rivers but the problems associated with flash floods have become very severe. Political factors have been a major obstacle in developing a master plan for flood control. However, recently a cooperative approach, involving more than 40 governments, administering the numerous towns in the metropolitan area, has been formulated and will very likely be adopted for implementation. The city has adequate water supply coming from the Missouri and Kansas rivers and the alluvial aquifers. Low-level contamination of the water supply had occurred in the past, but the problems were effectively remediated and no long-term pollution of the water supply system has since occurred. Instances of poor disposal practices of hazardous wastes are known; efforts are underway to clean up these sites. Numerous buildings and other structures have been completed in the area during the past 25 yrs. Kansas City now boasts of having the tallest building in the states of Missouri and Kansas—the One Kansas City Place stands at 183 m (600 ft), 4 m (13 ft) taller than the tallest building in St. Louis, One Bell Center. Many other ambitious construction projects are in various stages of development. A discussion of geotechnical characteristics of the foundation materials along with a list of major buildings in relation to site conditions and design features are included in the paper.

Evaluation of the Potential for Expansion and Cracking of Concrete Caused by the Alkali-Carbonate Reaction

AbstractAlkali-carbonate reactive rock was inadvertently used in the Cornwall and Ottawa areas of Ontario between 1978 and 1982. The excessive expansion and cracking caused by this reaction resulted in the need to replace concrete within three years of construction. This reaction of dolomitic limestone with the alkalies from cement is well known in the Midland-Kingston areas of Ontario. It had not been expected in the Cornwall and Ottawa areas. In an effort to prevent further occurrences of this reaction, 17 quarries in the Gull River Formation were studied. Aggregate durability tests, chemical analysis, and concrete prism expansion tests were conducted on 26 bulk aggregate samples. Concrete prism expansion tests were conducted at alkali contents of 1.25 and 3.0% sodium oxide (Na2O) equivalent. Results showed that the current Canadian Standards Association specifications are inadequate for recognizing some alkali-carbonate reactive aggregates. This was due to the occurrence of delayed expansive aggregate. It is recommended that the concrete prism expansion test be conducted using cement with an alkali content of 1.25% Na2O. Those aggregates that exceed 0.025% expansion at one year should not be used in highway structures exposed to deicing salt. A rapid chemical screening test is proposed. The determination of the calcium oxide to magnesium oxide (CaO:MgO) ratio and alumina content or insoluble residue can be used to screen potentially alkali-carbonate expansive rocks from those that are nonexpansive.

Construction on expansive rock : Logani, K L Proc 4th International Conference on Expansive Soils, Denver, 16–18 June 1980, Vol 1, P496–P513

Construction on expansive rock : Logani, K L Proc 4th International Conference on Expansive Soils, Denver, 16–18 June 1980, Vol 1, P496–P513

Foundations on expansive rocks in Brazil : Da Costa Numes, A J Proc 4th Congress International Society for Rock Mechanics, Montreux, 2–8 Sept 1979, Vol 1, P99–105. Publ Rotterdam, A A Balkema, 1979

Foundations on expansive rocks in Brazil : Da Costa Numes, A J Proc 4th Congress International Society for Rock Mechanics, Montreux, 2–8 Sept 1979, Vol 1, P99–105. Publ Rotterdam, A A Balkema, 1979

Alkali-aggregate reaction in nova scotia III. Laboratory studies of volume change

Studies of alkali-expansivity of Nova Scotia rock types included extensive lenght change tests of mortar bars and concrete prisms, and also cylinders immersed in alkali solution. The effects of such variables as alkali content, type of alkali, temperature, wet and dry cycling, anisotropy, optimum proportion of rock type, and the influence of pozzolan and fly ash were studied. Results obtained were correlated with petrographic studies so that potentially expansive rock types in the provinve may be recognized. Preventive measures applicable to field use were determined form analyses of expansion data.