A variety of engineering activities require reliable evaluation of rock strength. For instance, the stability of rock slopes depends on structural geology of rock massif in which the slope is excavated. Hoek-Brown (HB) failure criterion applied in rock design practice introduces factors based on the properties of jointed rock. The non-linear finite element safety calculation is conveniently used for calculation safety the factor of slope stability. The Mohr-Coulomb (MC) failure (strength) criterion for soil is widely applied in geotechnical design. Therefore, the appropriate transformation from HB to the equivalent MC, employing angle of shearing resistance φ and cohesion c, is necessary. This article studies the effect of jointed rock massif properties on the transformed MC parameters by using Sobol’s global sensitivity analysis (SSA) and HB transformation equations. Statistical parameters needed for the evaluation of sensitivity analysis are processed using classical statistical methods upon the emulation of Latin Hypercube Sampling simulation methods. Developed and adapted by authors techniques are illustrated by processing real rock investigation data from survey of the trachyte massif located in the Czech Republic. The first and higher order effects of random inputs are identified using SSA. It is illustrated that the effects of inputs on the MC parameters varies significantly depending on the discontinuity distribution and height of the slope.

The paper presents an application of statistical and numerical methods for the determination of the forcedisplacement curves and that of pullout capacity of prestressed grouted ground anchors installed in Miocene clay. A regression analysis of data from a database of acceptance test records for ground anchors to create has been performed, the force-displacement curve of the tested anchor corresponding to the range of loads applied for acceptance tests has been created. A linear regression model, employing the weighted least squares method and robust standard errors techniques were concluded to serve as a reliable statistical method suitable for achieving this goal. The discovered linear regression dependence then served as a lower control limit for the displacement values calculated at the anchor head applying the numerical model. A finite element model has been created to predict the behaviour of ground anchors being installed in fine-grained soils. The developed numerical model that employs Mohr-Coulomb strength criterion constitutive model evaluates the influence of high-pressure grouting by development additional radial stresses and that of an increment of fixed length diameter.

Wood has a long tradition of use as a building material due its properties and availability. However, it is very sensitive to moisture. Wood components of building structures basically require a certain level of moisture protection, and thus moisture monitoring to ensure the serviceability of such components during their whole lifespan while integrated within buildings is relevant to this area. The aim of this study is to investigate two moisture monitoring techniques promoting moisture safety in wood-based buildings (i.e., new structures, as well as renovated and protected buildings). The study is focused on the comparison of two electrical methods that can be employed for the nondestructive moisture monitoring of wood components integrated in the structures of buildings. The main principle of the two presented methods of the moisture measurement by electric resistance is based on a simple resistor–capacitor (RC) circuit system improved with ICM7555 chip and integrator circuit using TLC71 amplifier. The RC-circuit is easier to implement thanks to the digital signals of the used chip, whilst the newly presented integration method allows faster measurement at lower moisture contents. A comparative experimental campaign utilizing spruce wood samples is conducted in this relation. Based on the results obtained, both methods can be successfully applied to wood components in buildings for moisture contents above 8%.

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The contribution is focused on investigation of strains in a rock specimen during uniaxial compression test. Three components of strain occur in cylindrical shape specimen: axial, radial and volumetric. Determination of the strains is possible by using of local sensors. Strain gauges fixed on specimen surface were used in this study. Axial and radial components of strain were measured directly, and volumetric strain was calculated. Two types of rock were tested, syenite and sandstone, to illustrate variability of strain behaviour of rocks. Strain measurement is necessary for determination of Young's modulus and Poisson's ratio. Moreover, early states of failure can be identified by volumetric strain which is considerably sensitive to failure states.

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This contribution brings overview of mechanical properties of greywacke with focus on fracture mechanics parameters. Investigated rock type is clastic sediment, relatively widespread in Moravia region. The rock type is significantly utilized in construction industry. For purposes of this study, Kobeřice quarry was selected as sampling locality. Mechanical properties were investigated by deformation controlled 3-point bending test. Chevron notch was created on specimens in order to study fracture mechanics parameters. Moreover, deformation controlled uniaxial compression tests were carried out, as well. Specimens were equipped with strain gauges; thus, elastic modulus and the Poisson’s ratio could be determined. Splitting tensile test was employed in order to determine tensile strength. Mean value of fracture toughness KIC was determined to 1.85 MPa·m0.5. Mean value of uniaxial compressive strength was observed at level of 211 MPa and tensile strength reached 19.4 MPa. Hence, the tested greywacke was considered as high strength rock. Brittle type of failure occurred during the tests. The obtained results were compared with values reported for clastic sediments from several localities in the Czech Republic. Moravian greywacke reached significantly high strength in comparison to other clastic sedimentary rocks and can be considered as valuable raw material for purposes of construction industry.