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This paper presents the impact of selected essential aspects of geological structure on the state of slope stability as assessed by changes in the safety factor (SF). The engineering geological slope features that were analysed include: (i) changes in soil cohesion and internal friction angle, (ii) presence of a weak soil layer and its span, (iii) structural discontinuity (i.e. fault), (iv) soil permeability properties and water conditions (i.e. groundwater level, long and heavy rainfall). A certain scheme of slope stability calculations has been proposed for a case involving complex geological conditions. The numerical modelling of a hypothetic slope was performed using the shear strength reduction method based on the finite element method.

The slopes of open-pit mines are often at risk of failure. To identify this hazard, stability analyses are performed. An important element of these stability analyses is the reliable selection of input parameter values for the calculations. This selection is difficult because the slopes of the open pit are disturbed by mining activities. In such conditions, rheological processes, intensified by weathering, develop in open-pit slopes. This study is aimed at setting the strength parameters for the stability analysis of open-pit slopes with a developed slide process, using the random set method. The study was performed on the example of the open pit of the Bełchatów lignite mine, central Poland. A four-stage methodology, according to the random set method, was proposed. The methodology covered the following: site investigation, sensitivity analyses, shear strength reduction (SSR) analyses using numerical calculations, and probability analyses of the factor of safety (FoS) calculation results. The setting of the input parameters took into account the peak and residual strength parameters for each lithological unit in the physical model of the open-pit slope. Samples for laboratory tests were taken from the cores of nine test boreholes. The sensitivity analysis included all peak and residual strength parameters for each lithological unit in the body. As a result of the sensitivity analysis, specific strength parameters were adopted that would have a great impact upon the results of the calculations. Selected sets of parameter values were then used for the FoS calculations. The resultant FoS values revealed the probable slide planes. The positions of the slide planes were consistent with the interpreted slide surfaces based on the control boreholes and terrain observations. Knowledge of the slide planes positions and the values of the strength parameters enabled the designing of a securing approach for this landslide, and the taking of preventive measures to reduce this risk.

Industrial waste from the production of metallic silicon and silicon&ndash, iron alloys, which includes silica fumes (microsilica), is subject to numerous applications aiming at its reuse in concrete and polymeric composites. Recycling solves the problem of their storage and adverse environmental impact. Six different formulas of epoxy resins were tested, differing in the type of polymer, the mixing process (sonication or not) and the presence of microsilica. The study showed that microsilica added to the epoxy resin changes its viscosity and free surface energy, and these are the parameters that determine the adhesion of the polymer to the concrete surface. Strength tests and SEM analysis have determined how microsilica molecules can penetrate the structure of polymer macromolecules by filling and forming temporary chemical bonds. Mixing the fillers with the adhesive was achieved by using a sonication process. The analysis of the obtained results showed that, depending on the initial composition of the polymer, the addition of microsilica can change the chemical, physical and mechanical properties of the hardened adhesive to varying degrees. In the case of adhesives used in the construction industry to strengthen and glue structural elements, these changes significantly affect the durability of the adhesive joints.

WOS: 000451757200009, Research on sustainable concrete has drawn scientist's attentions on industrial by-products and wastes. Thus, consumption of raw materials would be diminished. In this study alkali activation of electric arc furnace slag (EAFS) was studied with a comprehensive test program. Different silicate modulus, sodium concentrations, curing conditions, curing temperatures and relative humidity condition variables were selected. Their effects on mechanical and micro structural behaviors of the mortar were investigated through SEM - XRD analyses. Result of this study, EAFS was activated with sodium hydroxide and sodium silicate solutions. Test results also revealed that increase in relative humidity, curing temperature and curing time had positive effects on strength parameters due to diminishing micro cracks and altering hydration reactions. With the current study utilization of EAFS is thought to be successfully disposed.

The data in this article are related to “Assessment of Sandcrete Blocks Manufacturers ‘Compliance to Minimum Standard Requirements by Standard Organisation of Nigeria in Southwest, Nigeria” (Ajao et al., 2018). The data shows the compliance level of Sandcrete Block Manufacturers to Minimum Standard Requirement in Southwest, Nigeria. Experimental procedures carried out on aggregates and sandcrete blocks included sieve analysis to determine grading distribution sizes and bulk density and compressive strength to determine the strength parameters. The results of the experiment were presented in charts and graphs. Keywords: Aggregates, Experimental procedure, Sandcrete blocks, Standards, Strength parameters

The quality of designed structures embedded in rocks is strongly related to rock strength parameters of intact rock. Measuring different parameters from tests could be very expensive in designing phase of projects. Estimating some parameters from other ones can reduce costs and time of project procedure. In this paper, the relationships between static and dynamic parameters of marls are studied by using the single and multiple linear regressions. For this purpose, several marl core samples from Seydoon region, Khoozestan Province in Iran are collected and tested. Some equations with sufficient correlation have been obtained to predict the engineering parameters of marls, especially the uniaxial compressive strength (UCS).

In this study, the effects of different shear rates during direct shear tests on variations in the strength characteristics were investigated for the sand samples of various particle size distribution. Direct shear tests were carried out at nine different shear rates ranging from 0.05 to 5 mm/min under normal stresses of 54.5, 109, and 218 kPa. Both sample groups were tested under a condition of defined water content and in a water-filled condition. Results show that with increasing shear rate, the internal friction angle and peak shear strength values increased. The increase in the internal friction angles and peak shear strengths were particularly evident for shear rates higher than 1 mm/min. Even though the effect of grain size on the variation in strength parameters due to shear rate is limited for the soils examined in this study, the effect should be considered. C1 [Beren, M.; Undul, O.] Istanbul Univ Cerrahpasa, Istanbul, Turkey. [Cobanoglu, I.; Celik, S. B.] Pamukkale Univ, Denizli, Turkey.

A new method is proposed in order to estimate the shear strength of schistosity planes in slate in terms of Mohr-Coulomb cohesion and internal friction angle. The procedure consists in carrying out the Brazilian method under different loading-foliation angles, for which experimental tests were achieved in slates from the northwest of the Iberian Peninsula (Spain). The experimental fracture patterns were analytically studied and justified by simulating the stress field in the discontinuity planes contained in the whole sample, taking into account the first failure registered in the tests. By combining experimental and analytical studies and a procedure based on the representation of the threshold state of stressesin the elastic regimein the failure plane, it is possible to estimate the foliation's strength envelope through a lineal adjustment according to the Mohr-Coulomb criterion and, thus, to characterize the layering. Finally, the proposed procedure was validated by the direct shear test. The cohesion and the internal friction angle obtained with this convenctional test were very close to that calculated by the proposed method, verifying the methodology developed by the authors. This procedure may be interesting in various engineering applications, either in the study of the properties of cleavage in slate, which is commonly used as an industrial rock, or in dam foundations, underground excavations and slope engineering, since one of the main failures in civil engineering is due to sliding along weak planes. The authors of this paper would like to acknowledge the financial support of the PhD fellowship Severo Ochoa Program of the Government of the Principality of Asturias (PA-14-PF-BP14-067). Also, the authors are grateful to editors and reviewers for their suggestions and help us to improve this manuscript.

The effect of capillary water caused by heavy rainfall and groundwater level fluctuations can induce the erosion and collapse of island reef coral sand foundations. Here, the effects of water content (&omega, ) on the shear strength parameters of coral gravelly sand are analyzed at the macro and micro scales by laboratory consolidated-drained triaxial compression and nuclear magnetic resonance tests. Furthermore, particle breakage characteristics of coral gravelly sand under the static load are discussed. With increasing &omega, (1) the internal friction angle increases slightly (&lt, 1&deg, ) then decreases, (2) the apparent cohesion is more sensitive to the change in the &omega, (3) with an increase from 5.4% to 21.3%, the bound water content remains almost unchanged, (4) the capillary water content is the main factor impacting the apparent cohesion, (5) the increase in free water content is the internal cause of the decreasing internal friction angle of coral gravelly sand with &omega, &gt, 11.1%, and (6) the particle breakage increases, and there is an approximately linear relationship between the median particle diameter (d50) and relative breakage index (Br). The established physical model can reflect the influence of water content and plastic work and describe the evolution law of particle breakage.

In this study, mechanical properties electromagnetic (EM), and shielding effectiveness of concrete samples containing boron product and wastes was investigated in details. In order to increase shielding effectiveness of concrete samples from electromagnetic waves, hardened concretes containing boron product and wastes are analyzed according to the Institute of Electrical and Electronics Engineers (IEEE) standards. In addition, the effects of the additives on the strength behaviors of the concretes are also examined to report that besides improving shielding behavior, addition of the minerals would not diminish strength parameters. As a result, the concretes containing boron product and wastes provides 3.16 to 100 times better shielding effectiveness than that of concrete containing only Portland cement which is the control sample. While the additives increase or do not affect negatively compressive strength of the concrete. As a conclusion, additives in concretes enhance shielding effectiveness without affecting the strengths parameters negatively. © 2020 Elsevier Ltd

The research concerned the possibility of using the microplasma welding technique for joining thin titanium alloy Grade 5 (6Al-4V) sheets. For this purpose, titanium reference samples without welds (Type 1) and two types of welded joints (butt joint - Type 2 and Type 3 overlap joint) were made with selected microplasma welding parameters for which strength parameters were determined and compared with the strength of the native material. The assessment of the connection quality was made on the basis of a monotonic tensile test. A metallographic analysis of the welded joints was made and the breakthroughs sample obtained during the tests was also carried out. In addition, strain distributions were determined in loaded sample types, which allowed investigating the impact of the heat affected zone size on the strength of welded joints subjected to monotonic tensile tests and Vickers hardness tests. Microplasma welded joints displayed relatively high brittleness. The failure locations are still influenced by heat affected zone despite the highly concentrated plasma beam of the microplasma arc welding. © 2018 Elsevier Ltd

In this study, experimental tests based on monotonic tension of specimens made from several types of heat-shrinkable films with various overprints were performed. Basic strength parameters of films were determined, such as Young's modulus, yield stress, tensile strength, and tensile strain at tensile strength. The effects of both the type of film and the type of overprint on the aforementioned parameters were studied. Earlier results of tests on similar materials, known in the literature, were referred to, and similarities and differences were pointed out. Film heat-shrinkability tests at temperatures 70, 80, 95 °C were also conducted, indicating certain patterns between the material's mechanical properties and the degree of shrinkage. © 2017 Elsevier Ltd

The evolution of micro-cracks in rocks under different strain rates is of great importance for a better understanding of the mechanical properties of rocks under complex stress states. In the present study, a series of tests were carried out under various strain rates, ranging from creep tests to intermediate strain rate tests, so as to observe the evolution of micro-cracks in rock and to investigate the influence of the strain rate on the deformation and strength properties of rocks. Thin sections from rock samples at pre- and post-failure were compared and analyzed at the microscale using an optical microscope. The results demonstrate that the main crack propagation in the rock is intergranular at a creep strain rate and transgranular at a higher strain rate. However, intergranular cracks appear mainly around the quartz and most of the punctured grains are quartz. Furthermore, the intergranular and transgranular cracks exhibit large differences in the different loading directions. In addition, uniaxial compressive tests were conducted on the unbroken rock samples in the creep tests. A comparison of the stress&ndash, strain curves of the creep tests and the intermediate strain rate tests indicate that Young&rsquo, s modulus and the peak strength increase with the strain rate. In addition, more deformation energy is released by the generation of the transgranular cracks than the generation of the intergranular cracks. This study illustrates that the conspicuous crack evolution under different strain rates helps to understand the crack development on a microscale, and explains the relationship between the micro- and macro-behaviors of rock before the collapse under different strain rates.

A soil-structure interface is defined as the contact surface between a soil and a structure through which stresses are transferred from the soil to the structure or vice versa. The ultimate shear strength at the interface is one of the key parameters required for the design and safety assessment of a structure in the soil, such as pile foundations, retaining walls, buried pipelines, and soil nails. In this paper, the shearing behavior of completely decomposed granite soil and steel interfaces is examined using a modified suction-controlled direct shear apparatus. A series of direct shear tests was performed on two different types of soil-steel interfaces under different stress state variables. The experimental results were used to investigate the influence of counterface roughness on the failure envelopes of soil-steel interfaces. Test results show that matric suction has a significant influence on the shear behavior and shear strength of the interfaces. It has been observed that the critical interface shear strength for a specific counterface roughness and net normal stress (NNS) depends on the applied matric suction. Also, both the peak and the postpeak shear stresses are greatly influenced by variation in NNS. Furthermore, the experimental shear strength data are compared with an analytical model that considers the influence of suction and dilation on an apparent interface friction angle. It is noted that, for the applied NNS and matric suction, the analytical model works well for both rough interfaces. (C) 2016 American Society of Civil Engineers.