Strength Characteristics Of Rock Mass Research Articles

Mehaničko ponašanje stijenske mase pri ispitivanju smicanja simuliranih materijala

In this paper, the influence of joint distribution on the deformation and strength characteristics of rock mass is studied through direct shear tests of five typical distribution types of simulated materials including two joints. The spatial distribution pattern of joints determines the deformation and failure process and the final shape of rock mass, which is mainly manifested as lap failure between joints. By comparing the 25 stress-strain curves obtained from the test, the stress-strain curves are classified into five types. With the increase of the normal stress, the composite shear type gradually transforms to the shear type, and the shear type gradually transforms to the yield type. The joint distribution pattern has a great influence on the shear strength and the maximum difference is 64 %.

Impact of blasting on pit wall rock mass

The paper presents the research findings obtained by the Institute of Mining in drilling and blasting in Dzhetygara open pit mass. The research was aimed at enhanced stability of stationary benches and at cost minimization of drilling and blasting. The research met two objectives. First, in terms of Dzhetygara deposit, perimeter blasting designs were developed, which ensured reduced impact of blasting on adjacent rock mass. Second, the blast-induced PPV measurement procedure was refined and introduced, and the blasting technology was improved for blasting operations at ultimate pit limit. The special technology for ultimate pit perimeter blasting includes: analysis of blast effects on pit wall rock mass; finding of mechanisms of wave processes in rock mass; interaction of perimeter blasts depending on strength characteristics of rock mass; field trial of cutback methods; determination of sequence of blasts when approaching a guarded sites; determination of efficiency criteria of drilling and blasting.

Оценка прочности массива горных пород при разработке месторождений открытым способом

The paper presents results of an experimental study on strength characteristics of the rock mass as applied to the assessment of open-pit slope stability. Formulas have been obtained that describe a correlation between ultimate and residual strength of rock samples and residual shear strength along the weakening surface. A new method has been developed to calculate residual interface strength of the rock mass basing on data from the examination of small-scale monolith samples with opposing spherical indentors. A method has been proposed to estimate strength characteristics (structural weakening coefficients and internal friction angles) of the fractured near-slope rock mass. The method relies on test data from shattering small-scale monolith samples with spherical indentors, taking into ac- count contact conditions along the weakening surface, and can be applied in the field conditions. It is acceptable to use irregular-shaped samples in thetests.

Reliability analysis of three-dimensional rock slope

Reliability analysis is generally regarded as the most appropriate method when uncertainties are taken into account in slope designs. With the help of limit analysis, probability evaluation for three-dimensional rock slope stability was conducted based upon the Mote Carlo method. The nonlinear Hoek-Brown failure criterion was employed to reflect the practical strength characteristics of rock mass. A form of stability factor is used to perform reliability analysis for rock slopes. Results show that the variation of strength uncertainties has significant influence on probability of failure for rock slopes, as well as strength constants. It is found that the relationship between probability of failure and mean safety factor is independent of the magnitudes of input parameters but relative to the variability of variables. Due to the phenomenon, curves displaying this relationship can provide guidance for designers to obtain factor of safety according to required failure probability.

Determination of joint roughness coefficient (JRC) for slope stability analysis: a case study from the Gold Coast area, Australia

Surface roughness of rock discontinuities is an important factor that determines the strength characteristics of rock mass. Joint roughness coefficient (JRC), which is typically measured by means of Barton’s combs in the field, is widely used to describe the joint roughness. However, this traditional method of measurement can be rather subjective, labor-intensive and time consuming. In contrast, photogrammetry can provide an alternative method to obtain relatively simple and fast measurements of JRC based on high resolution 3D models. However, the reliability of such measurements still remains an issue as the results from photogrammetry can be affected by the quality of images. This study seeks to clarify whether photogrammetry can produce accurate measurements of JRC that can be used to assess the stability of slopes. A rock slope with a recent wedge failure in the Gold Coast area, Australia was selected for this purpose, and three different methods such as manual measurements, photogrammetry, and tilt tests were employed to determine the JRC. The obtained results showed some discrepancy in the values of JRC obtained from these three different measurements. In particular, the JRC obtained using the Barton’s comb had slightly higher values compared to those determined through the photogrammetry method while the tilt test results tended to yield overestimated values of JRC. Computer analysis using Universal Distinct Element Code was also performed to study the effect of JRC variation on the slope stability. It was found that an increase in the JRC led to an increase in the safety factor of the slope.

Structural Plane of Rock Mass Strength Characteristics and its Impact on Groundwater

The strength characteristic of discontinuity is one of the most important mechanical characteristics of rock mass, and its strength dominates the strength and deformation of joint rock mass. The underground water has an important influence on the strength of discontinuity. In this paper, the strength theory of joint rock mass was summarized and analyzed; further, two kinds of failure mode of joint rock mass which are joint shear failure and rock shear failure were proof. Considering the impact of underground water, the effective stress principle was introduced, and base on it, the joint shear failure strength rule of the saturated rock mass was built. When the influence of underground water on joint strength is studied, the shear strength formula has important theoretical and realistic significance.

Structural Plane of Rock Mass Strength Characteristics and its Impact on Groundwater

Structural Plane of Rock Mass Strength Characteristics and its Impact on Groundwater