Quantifying stresses and support requirements in the undercut and production level drifts of block and panel caving mines

A numerical modelling strategy has been developed in order to quantify the magnitude of induced stresses at the boundaries of production level and undercut level drifts for various in situ stress environments and undercut scenarios. The results of the stress modelling were in line with qualitative experiential guidelines and a limited number of induced stress measurements documented from caving sites. A number of stress charts were developed which quantify the maximum boundary stresses in drift roofs for varying in situ stress regimes, depths and undercut scenarios. This enabled many of the experiential guidelines to be quantified and bounded. A limited number of case histories of support and support performance in cave mine drifts were compared to support recommendations using the NGI classification system, The stress charts were used to estimate the Stress Reduction Factor for this system. The back-analyses suggested that the NGI classification system might be able to give preliminary estimates of support requirements in caving mines with modifications relating to rock bolt length and the support of production level intersections. (C) 2002 Elsevier Science Ltd. All rights reserved.

Modelling the size of the crushed zone around a blasthole

A new model to predict the extent of crushing around a blasthole is presented. The model is based on the back-analysis of a comprehensive experimental program that included the direct measurement of the zone of crushing from 92 blasting tests on concrete blocks using two commercial explosives. The concrete blocks varied from low, medium to high strength and measured 1.5 in in length, 1.0 m in width and 1.1 m in height. A dimensionless parameter called the crushing zone index (CZI) is introduced. This index measures the crushing potential of a charged blasthole and is a function of the borehole pressure, the unconfined compressive strength of the rock material, dynamic Young's modulus and Poisson's ratio. It is shown that the radius of crushing is a function of the CZI and the blasthole radius. A good correlation between the new model and measured results was obtained. A number of previously proposed models could not approximate the conditions measured in the experimental work and there are noted discrepancies between the different approaches reviewed, particularly for smaller diameter holes and low strength rock conditions. The new model has been verified with full scale tests reported in the literature. Results from this validation and model evaluations show its applicability to production blasting. (C) 2003 Elsevier Science Ltd. All rights reserved.

Rock fracture mean trace length estimation and confidence interval calculation using maximum likelihood methods

There has been a resurgence of interest in the mean trace length estimator of Pahl for window sampling of traces. The estimator has been dealt with by Mauldon and Zhang and Einstein in recent publications. The estimator is a very useful one in that it is non-parametric. However, despite some discussion regarding the statistical distribution of the estimator, none of the recent works or the original work by Pahl provide a rigorous basis for the determination a confidence interval for the estimator or a confidence region for the estimator and the corresponding estimator of trace spatial intensity in the sampling window. This paper shows, by consideration of a simplified version of the problem but without loss of generality, that the estimator is in fact the maximum likelihood estimator (MLE) and that it can be considered essentially unbiased. As the MLE, it possesses the least variance of all estimators and confidence intervals or regions should therefore be available through application of classical ML theory. It is shown that valid confidence intervals can in fact be determined. The results of the work and the calculations of the confidence intervals are illustrated by example. (C) 2003 Elsevier Science Ltd. All rights reserved.

Geotecnia urbana da zona ribeirinha de Vila Nova de Gaia (Cais de Gaia, Santa Marinha – Lavadores, Canidelo): uma avaliação preliminar

Mestrado em Engenharia Geotécnica e Geoambiente

Исследование геофизическими методами инженерно-геологических условий в районе строительства гидроэлектростанции (ГЭС) на реке Мтквари

მდინარე მტკვარზე ჰიდროელექტროსადგურის მშენებლობის რაიონის საინჟინრო-გეოლოგიური პირობების გამოკვლევა გეოფიზიკური მეთოდებით გეოფიზიკური გამოკვლევების შედეგად შესწავლილია მდ. მტკვარზე ჰიდროელექტროსადგურის მშენებლობის რაიონის საინჟინრო-გეოლოგიური პირობები. დადგენილია იქ გავრცელებული ნალექების სიმძლავრეები და ფიზიკური პარამეტრები. გამოვლენილია მეწყრული და პოტენციურად მეწყერსაშიში უბნები და დადგენილია მათში ფილტრაციის გაბატონებული მიმართულება. შეფასებულია ჰეს მშენებლობის რაიონის სეისმურობა.

Исследование инжинерно-геолргических и гидрогеологических условии Бакурианского плато экспресс-методом электроразведки с использованием программного обеспечения IPI2WIN

ელექტროძიების ექსპრეს-მეთოდით პროგრამული უზრუნველყოფის IPI2WIN გამოყენებით კვლევის მიზანს წარმოადგენს ბაკურიანის პლატოზე გავრცელებული ნალექების საინჟინრო-გეოლოგიური და ჰიდროგეოლოგიური პირობების დაზუსტება ცენტრალური პროფილის მაგალითზე. IPI2WIN პროგრამული უზრუნველყოფით მიღებული კუთრი ელექტრული წინაღობის ჭრილი კარგ თანხვედრაშია ტრადიციული პალეტური ინტერპრეტაციის შედეგად მიღებულ (I-I’) გეოელექტრულ ჭრილთან.

Изучение инжинерно-геологических условии Бугеуьского (Рача) оползня геофизическими методами разветки

ბუნებრივი ელექტრული ველის მეთოდით განისაზღვრა ბუგეულის მეწყერზე მიწისქვეშა წყლების მოძრაობის მიმართულება, დადგინდა მათი დინების საკმაოდ მაღალი სიჩქარე და დაფიქსირდა დამეწყრილი მასის ბოლო ნიშნულები.

Use of electrical resistivity to identify collapsible soils in Brazil

Three soil profiles in Ilha Solteira, Brazil were investigated to establish their potential for collapsible behavior. The soil profiles were identified using terrain evaluation techniques and simple laboratory tests. Geophysical surveys were undertaken as they are quick and relatively cheap. The results were correlated with trial pit descriptions and cone and standard penetration tests. The study has shown that electrical resistivity is a useful tool for the preliminary identification of horizons of collapsible soils, before more expensive intrusive and laboratory work is undertaken.

Metal transport parameters of a gneiss saprolitic silty soil for liner design

Diffusion coefficients and retardation factors of two metal cations (Cd2+ and Pb2+) were measured for a compacted Brazilian saprolitic soil derived from gneiss, aiming to assess its geoenvironmental performance as a liner for waste disposal sites. This soil occurs extensively all over the country in very thick layers, but has not been used in liners because of its hydraulic conductivity, higher than 10(-9) m/s when compacted at optimum water content of standard Proctor energy, but which can be reduced by means of appropriate compaction techniques or additives. Batch, column, and diffusion tests were carried out with monospecies synthetic solutions at pH 1, 3, and 5.5. Measured diffusion coefficients varied between 0.5 and 4 X 10(-10) m(2)/s. Retardation factors show that cadmium, a very mobile cation, is not adsorbed at pH I but is significantly retained at pH 3 and pH 5.5, whereas lead is retained at all tested pH values though slightly at pH 1. Estimated retardation factors from batch tests were 1.3-2.3 times those resulting from column tests and at its highest when obtained by diffusion tests; whereas batch tests allow a more complete exposure of the soil grains to the solution, time-dependent nonspecific adsorption may take longer to occur. The importance of contact time was observed and should be considered in further investigations. Its significant retention of metals suggests a promising utilization of this soil as a bottom liner for wastes landfills.

Elaboração da carta geotécnica de suscetibilidade de um trecho da rodovia marechal rondon - sp-300 (SP, Brasil)

The highways are enterprises of great longitudinal extension that cross several types of lands, that possess different geologic, geomorphologic, pedologic and vegetation conditions. In the environmental management of highways the importance of the use of Engineering Geological Maps of Susceptibility was noticed, for being documents that inter-relates several information of the environment. This way, this research objectified the elaboration of this type of map and the indication of lines of direction for the conservation of the Highway Marechal Rondon - SP-300. For its elaboration the Map of Declivity, the delimited Homogeneous Physiographic Units, the processes of the superficial dynamics mapped and the use of the ground was used. Its elaboration evidenced its importance for the environmental management of highways, in view of the prevention, the monitoring and the correction of the adverse processes that can occur in this type of enterprise.

Carta geotécnica de suscetibilidade aos processos da dinâmica superficial do trecho KM 215 ao 249 da Rodovia Marechal Rondon - SP-300

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Proposta de sistemática para tomada de decisão relativa a movimentos de massa gravitacionais: aplicação em Ouro Preto (MG)

Pós-graduação em Geociências e Meio Ambiente - IGCE

Mapeamento geológico-geotécnico por meio do método do detalhamento progressivo: ensaio de aplicação na área urbana do município de Rio Claro (SP)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Caracterização geotécnica com base na compartimentação fisiográfica: aplicação em Poços de Caldas - MG

This work presents a comparison of alkaline and cristaline terrains of an area inside a Poços de Caldas (MG) contry for appropriate urban expansion. The study area has 52km2 through rural and urban terrains with geological and geomorphological differences. At present Poços de Caldas has more than 130 thousand people and expansion government plans are from 1993 showing the necessity of studies of infrastructure to population and tourists. At last 40 years the city became a place with job offers in bauxite minning causing a population increase about 200%. At this way this work uses the Vedolvello (2000)´s method of terrains physiographic compartimentalization (UBCs) with integrated analysis (Land Systems) made by remote sensing products (air photos). After that field trips was performed to check unity limits by observation of rocks, relief and weathering soil profile. The main results are Engineering Geological Map and a classification table of Basic Units of Compartimentalization to presents the characteristics to uses and soil occupation.

Carta geotécnica de suscetibilidade aos processos de dinâmica superficial na região do Bairro do Peão, Piracaia (SP)

This research presents the result of the engineering geological mapping in a 1:50.000 scale, in Bairro do Peão region, in Piracaia (SP), represented by means of homogeneous units which are susceptible to superficial dynamic processes. To serve as basis for the elaboration of a Chart of Susceptibility to Processes of Superficial Dynamic, a series of physical samples was collected, considering erosive processes and registers of information of usage and soil occupation. The procedure used for elaborating the geotechnical chart is based on Vedovello (2000), which suggests the physiographic compartimentation of the area through photointerpretation and further geotechnical characterization of the selected samples. The geotechnical characterization of the samples was made by identifying the features and properties of the material and forms of the physical environment determining the geotechnical conditions through geological-geotechnical profile descriptions typical of/ peculiar to each unit defined in the area. Thus, for each unit selected, the susceptibility level was established in very high, high, average and low, as well as the prevalent erosive processes.