Impact of water saturation effect on sedimentary rocks strength properties

Abstract

IMpAct of wAter sAturAtIon effect on seDIMentAry rocKs strenGth propertIes purpose. To identify some regularities of reduction in strength of loamy soils and weak sedimentary rocks that are typical for Western Donbas by water saturation condition for assessment of their stability in geotechnologies and forecasting geohazards. Methodology. The paper presents two techniques of experimental testing for sedimentary rocks that allow determining their strength properties under the condition of water saturation. Rock samples of sandstones, mudstones, and siltstones after artificial saturation with mine water were tested on a KL 200/CE hydraulic press to determine the uniaxial compressive strength value. The method for determining the physicalmechanical properties for soft loamy rock samples under different water saturation using PS10 singleplane shearing tester was used. findings. Based on the results of compression tests, strength characteristics are obtained for samples of sandstones, mudstones, and siltstones, in particular, the values of uniaxial compression strength at various degrees of water saturation. Statistical processing of the obtained experimental data was applied. A relative variation in the values of compressive strength was established for various rates of water saturation; regression dependences of the strength loss for sedimentary rocks depending on the water content in rock samples were plotted. The values of cohesion C and the angle of internal friction φ for soft loamy rocks are obtained depending on water saturation. originality. It was established that the relative variation of the uniaxial compressive strength increases with increasing water content in sedimentary rock samples. The most intense decrease in the strength of sandstones, mudstones, and siltstones samples occurs with increasing water content from 1 to 2 %. In a watersaturated state, the strength of some sedimentary rocks under con ditions of Western Donbas decreases by 1.5-2.5 times. The critical values of the strength properties of soft loamy rocks are estab lished depending on water saturation, at which deformation processes are initiated: for light yellow loess loams-C = 17 kPa and j = 14°; for yellowbrown dense loams-C = 29 kPa and j = 17°. practical value. Correction coefficients for water saturation were obtained to determine the estimated physical and mechanical characteristics of sedimentary rocks of Western Donbas, which allows predicting geomechanical processes in the rock mass and determining the parameters of geomechanical systems. The obtained values of cohesion and angle of internal friction for loamy rocks depending on water saturation allow predicting stable parameters of openpit slopes and dumps.

Multifactorial analysis of a gateroad stability at goaf interface during longwall coal mining – A case study

“…When exposed to water rocks lose 20-25% of their strength [33]. The coal formation is characterized by monoclinal bedding with the coal bed pitch (the dip angle of coal seam) of 6°.…”

Comparison of the Sample Preparation Strategies and Impacts on the Tensile Strength of Gas Shale with Variable Moisture Conditions

“…Debanjan et al found that shale degraded quickly while sandstone degraded slower until 80% saturation. Babets et al [18] saturated samples first, then dried them, finding that the strength of siltstones and mudstones decreased 1.5-2.5 times in a water-saturated state compared to when air-dried. Hasbollah et al [19] dried and partially soaked shale and sandstone, observing that the tensile strength and anisotropy rose with water content, and more so in shale.…”