Chemically dependent mechanical properties of natural andesite rock fractures

Abstract

Different engineering rock works are affected by chemical–mechanical coupling phenomena in rock mass. Friction, strength of fracture walls, shape of asperities, and roughness control hydraulic and mechanical behaviors of fractures, which are all affected by chemical solutions. In addition, the efficiency of some operations such as leaching depend on the fracture conductivity in a confined condition. To evaluate the effects of leaching agents on the mechanical and geometrical properties of andesite rock fractures, a set of laboratory-scale experiments were conducted on three types of andesite in a sulfate medium with different pH values. Although the cohesion and shear strength reduced by decreasing the pH value, the roughness and shear stiffness of fractures did not follow a unique trend. Scanning electron microscope images indicated that the reason is mainly due to the selective chemical dissolution of the more reactive minerals in acidic solution. It is shown that fracture conductivity is a strong function of confining stress, asperities resistance, and aperture in such a way that confining pressure decreases the conductivity appreciably and the reduction rate depends on the mineralogy of fracture surfaces.

The Physicomechanical Deterioration Characteristics and Mesoscopic Damage Analysis of Sandstone under Acidic Environment

“…It has become one of the emerging research focuses in the field of rock and environmental geotechnical engineering. Mohtarami et al [4,5] studied the effect of chemical solutions on the physical and mechanical properties of rocks and analyzed the chemical effect of rock fracture by the finite element method. Portier and Vuataz [6] studied the response of Enhanced Geothermal System (EGS) reservoir to chemical stimulation by numerical simulation of coupled thermohydraulic-chemical processes.…”

Review of close-range three-dimensional laser scanning of geological hand samples

“…In addition to the characterization of surface morphology, laser scanning can be applied for temporal analysis to assess changes of targets of interest over time, such as studies on weathering (Birginie and Rivas, 2005;Mohtarami et al, 2017) and deformation (Indraratna et al, 2014;Zhao et al, 2017). Birginie and Rivas (2005) used a laser scanner to monitor the degradation of limestone when exposed to salt spray.…”

“…Comparison of degradation between rock types can then be determined. Mohtarami et al (2017) also studied weathering effects using multi-temporal scans in order to simulate the acidic chemical solvents that are commonly used in rock engineering projects at heap leaching sites.…”

“…Herda (2006); Zhang et al (2017); Fan and Cao (2019); Li et al (2019) Developed new methodologies for calculating the JRC using the depth data from the 3D digital model of a core face scan. Birginie and Rivas (2005); Mohtarami et al (2017); Indraratna et al (2014); Zhao et al (2017) Scanned samples before and after induced weathering to compare the 3D digital models and assess the change due to the weathering. Multiple different core samples were also scanned before and after destructive tests to assess morphological changes in the samples.…”

Seepage Behaviour of Fractured Rock Mass Infilling Using Different Transfixion Rates under Cyclic Loading

“…The permeability of a jointed rock mass is closely related to the degree of joint filling and penetration [1][2][3][4][5]. The filling of joints in surrounding rock for underground engineering is characterized by random gap widths, occurrence complexity, and uncertainty in the transfixion rate, all of which significantly affect the permeability, shear strength, and stability of a rock mass [6][7][8][9][10][11]. The filling in a jointed and fractured rock mass is affected by the stress environment and usually undergoes an opening-closing-opening cycle which has a well-defined self-regulation ability.…”