Correlation between Schmidt hardness,uniaxial compressive strength and Young’s modulus for andesites,basalts and tuffs

Volcanic rocks from the Bodrum Peninsula have been studied to establish a relationship between the uniaxial compressive strength (UCS), Youngs modulus (E) and Schmidt hammer rebound number (N). Test results obtained on andesites, basalts and tuffs have been assessed statistically and the parameters obtained correlated. Regression equations were established between N, E and UCS.The study suggests the following empirical relationships: UCS=2.75 N–36.83, E=0.17 UCS+0.28 and E=0.47 N–6.25. The relationships are somewhat different from the correlations suggested by previous studies and should therefore be used only for andesites, basalts and tuffs with degrees of weathering and mineralogical structure similar to those used in the present study. The results obtained using solely the Schmidt hammer test for estimating mechanical properties of rocks are less accurate than when a full suite of laboratory tests is carried out but it is hoped that these empirical equations will help geotechnical engineers making practical decisions at a preliminary site investigation stage.     

Relationship between cleavage orientation,uniaxial compressive strength and Young’s modulus for slates in NW Spain

Slates from North Western Spain have been studied to establish the influence of the cleavage orientation on the uniaxial compressive strength (UCS) and Young’s modulus (E). Slate, sandstone and intercalated slate/sandstone lithologies were tested and the higher strengths were always obtained when the load was applied parallel, or close to parallel, to the slaty cleavage. This study suggests the following empirical relationships for unweathered slates in saturated conditions UCS = 0.037β ² − 7.622(β + 200.6, E × 10⁴ = 0.002β ² − 0.134β + 3.453. E can be estimated from UCS values using E × 10⁴ = 429,56 (UCS)^0.9122. These empirical equations will assist in geotechnical studies in this area of NW Spain where slate quarrying is an important industry.      

Determination of in situ uniaxial compressive strength of coal seams based on geophysical data

The central issue for pillar design in underground coal mining is the in situ uniaxial compressive strength (σ _cm). The paper proposes a new method for estimating in situ uniaxial compressive strength in coal seams based on laboratory strength and P wave propagation velocity. It describes the collection of samples in the Bonito coal seam, Fontanella Mine, southern Brazil, the techniques used for the structural mapping of the coal seam and determination of seismic wave propagation velocity as well as the laboratory procedures used to determine the strength and ultrasonic wave velocity. The results obtained using the new methodology are compared with those from seven other techniques for estimating in situ rock mass uniaxial compressive strength.      

Modified Mohr–Coulomb criterion for non-linear triaxial and polyaxial strength of intact rocks

Triaxial or polyaxial strength of rocks is required while analysing many civil and mining engineering structures in rocks. Mohr–Coulomb criterion is the most widely used strength criterion in rock engineering problems. In its present form the criterion suffers from two major limitations. Firstly, it represents the strength of rock as a linear function of confining pressure. Secondly, the effect of intermediate principal stress is not considered by this criterion. In the present study, this criterion is modified to take into account the non-linearity and effect of intermediate principal stress on strength behaviour. Barton's [1] critical state concept for rocks has been employed for this purpose. The applicability of the proposed simple non-linear triaxial and polyaxial strength criteria has been verified by applying them to experimental results for the intact isotropic rock material available from literature and comparing the prediction with the other popular criteria in vogue. The agreement has been found to be excellent. The applicability of the concept to jointed rocks will be discussed in separate publication.     

The influence of quartz content on modulus of elasticity and Poisson’s ratio in quartz sandstone

Bulletin of Engineering Geology and the Environment - The cemented soils by trench cutting re-mixing deep (TRD) wall or trench cutting assembled diaphragm (TAD) wall are a mixture of various soils....     

Zipf’s and Gibrat’s laws for migrations

This paper analyses the evolution of the size distribution of the stock of immigrants in the period 1960–2000. In particular, we are interested in testing the validity of two empirical regularities: Zipf’s law, which postulates that the product between the rank and size of a population is constant; and Gibrat’s law, according to which the growth rate of a variable is independent of its initial size. We use parametric and nonparametric methods and apply them to absolute (stock of immigrants) and relative (migration density, defined as the quotient between the stock of immigrants of a country and its total population) measurements. We find that both the stock of immigrants and migration density follow similar size distributions to those of cities and of countries. Contrary to what traditional migrations models predict, growth in the stock of immigrants is independent of the initial stock. Moreover, the growth of migration density shows a divergent behaviour, which could be explained by the lower birth rates of host countries and the reduction in the cost of emigration produced by the presence of a previous stock of immigrants in the country.     

Effects of pre-existing cracks and infillings on strength of natural rocks – Cases of sandstone,argillite and basalt

This study aims to examine the influence of pre-existing discontinuities on the strengths of four natural rocks of different origins. A series of unconfined compression tests was performed on specimens of two types of sandstones, argillite and basalt that contain open and filled cracks. It was found that the presence of cracks tends to decrease the overall strength for all studied rocks; however, the magnitude of strength reduction is related to the property of rock. The larger strength decrease was observed for the relatively harder argillite and basalt, compared to the softer sandstone. It was also found that the infill material could increase the strength of rock specimens, while the obtained strength depended on the characteristics of the fill material.     

Innovative potential for development of Europe’s neighbouring countries and regions

The European Neighbourhood Policy (ENP) is intended to promote development in bordering states and regions positioned along a broad arc from Morocco to Ukraine to become more friendly, stable, and prosperous. The policy offers limited but attractive terms of association with selected non-EU members concerning trade, mobility, innovation, and assistance in exchange for the adoption of important Western features that comprise the Community Acquis. The theme of this special issue hews closely to the economic development goals of the ENP by examining forces and factors that underlie the ability of neighbouring regions and countries to acquire and exploit innovative technologies, which are seen as the key element of a successful ENP.     

Re-examination of Zipf’s law and urban dynamic in China: a regional approach

Recent efforts have been made to interpret spatial-temporal evolution of urban system using Zipf??s law. The debates remain whether Zipf??s law holds true for large and diverse countries with long urbanization history, and how varied geographical settings with different socioeconomic conditions affect city-size distributions. This research investigates China??s urban system dynamics through expanded Zipf??s law at national and regional level. First, the paper revisits urban system dynamic theories and recent applications of Zipf??s law. The city data from 1960 to 2000 are then used to analyze rapid changes of urban systems in China through Zipf??s plots of cities over the entire nation and in six macro regions, respectively. The paper also examines top ten city rank changes nationally and regionally to examine temporal trajectories of key cities and the impacts on urban systems over space. Three types of Zipf??s law reflections are found over six China??s macro regions, based on the similarities of temporal dynamics of urban systems.     

Correlations of in situ modulus of deformation with elastic modulus of intact core specimens and RMR values of andesitic rocks: a case study of the İzmir subway line

Bulletin of Engineering Geology and the Environment - The main purpose of this paper is to obtain the rock mass rating (RMR) from different methods considering either the elastic modulus of intact...     

A model to measure compressive strength of compressed earth blocks with the ‘3 points bending test’

This article proposes a modelling of the ‘3 points bending test’ on compressed earth blocks (CEB) which will give their compressive strength. This test is already used in situ for CEB quality control. Conventional bending modelling gives the tensile stress at failure using three of the principal assumptions of the Strength of Materials theory, which are in fact not respected here. This is why it is proposed in this paper to model the arch behaviour in compression, which is of primary importance for aspect ratios less than three. Considering a proposed lattice, a behaviour at failure is obtained, close to that of a CEB during a 3 points bending test. The compressive stress at failure is obtained by using this lattice. The validation of the model is given using experimental data. Then the model gives information on the CEB structure such as isotropy, dry density gradient within the CEB, and effect of friction with the experimental direct compression test device, leading to confinement of the sample.     

Application of lignosulphonate—a sustainable approach towards strength improvement and swell management of expansive soils

Bulletin of Engineering Geology and the Environment - Long-term material dependency on natural resources has caused a heavy toll on the environment and biodiversity of natural systems. To explore...     

The River Nile and Ethiopia’s Grand Renaissance Dam: challenges to Egypt’s security approach

There are increasing challenges to Egypt’s security approach to the River Nile. The river is under immense pressure. This paper examines the significance of the Nile for Egypt and the factors and problems of diminishing its waters. It reviews Egypt’s long-time policy on the Nile and concludes that this policy is difficult to maintain in the face of the present and future challenges. It recommends a non-security multilateral solution for the benefit of all parties.     

The Two Facets of Lesotho’s Urban Land Law and Implications for Planning

Critical research and analysis of the link between urban development, urban law and judicial decisions in the cities of Sub-Saharan Africa is limited. Drawing on lessons from Maseru, Lesotho, this paper advances a critical analysis of the link between urban law, judicial decisions and urban development. The paper suggests that Lesotho’s urban land law, the Land Act of 1979 (LA 1979) has two facets. The first facet is that LA 1979 is exclusionary because in terms of access to urban housing land, it discriminates between individuals on the basis of their socioeconomic wealth and access to those who wield state power. The second facet is that LA 1979 is ostensibly empowering, as it has permitted urban residents who have acquired urban housing land through informal delivery processes to challenge state attempts to appropriate their land without compensation. The paper notes that the first facet has remained significantly unchanged since the enactment of LA 1979 in June 1980, while the second facet only emerged in 1993, when constitutional rule was reinstated after nearly 23 years of autocratic regimes. The paper concludes that the reinstatement of constitutional rule in 1993 has permitted the courts to reinterpret the rules-of-the-game in ways that have privileged the rights of ordinary urban residents over those of the state. In the process, the judiciary has established solid foundations for transparent, accountable, and participatory urban planning and governance, a culture that the planning profession in Lesotho is yet to internalise.

XXI. Century’s challenges for the regeneration of port cities – and for the regeneration of the Havana Bay and waterfront

Based on presentations and discussions during a one-week workshop at Havana, Cuba, in June 2017, the article gives an overview of conditions and options for the regeneration of the Havana Bay and the City of Havana. Although the City of Havana seems to be an excellent location for all kinds of international businesses and tourism because of its favourable geographic and climate conditions as well as its outstanding cultural heritage, many big problems must be solved in an ambitious regeneration process. In order to significantly enhance economic growth and development, it is required to remove some political and legal barriers, but even more it is needed to restore environmental and living conditions around the Havana Bay.     

Tests and analysis of mechanical behaviours of rock bolt components for China’s coal mine roadways

A series of laboratory tests were performed to study the mechanical behaviours of newly developed high strength rock bolt components, including rebar, thread, plate, and domed washer. The characteristi...