Effects of Pore Structure on Sandstone Mechanical Properties Based on Micro‐CT Reconstruction Model

Abstract

As porous, heterogeneous, and anisotropic material, the microscopic structure of the rock has a significant influence on its mechanical properties. Rare studies were devoted to this area using pore scale modeling and simulations. In this paper, different types of sandstones are imaged using micro-CT technology. The rock porosity is obtained by filtering, binarization, and threshold segmentation. The texture coefficient (TC) and the tortuosity of the rock skeleton are calculated by open source program, where the tortuosity of the rock skeleton is firstly used to characterize the microscopic structure of the rock. Combining with the rock mechanics parameters obtained in the laboratory, the simulation of uniaxial compression is performed on the reconstructed pore scale rock finite element mesh model by ANSYS software. Young’s modulus, compressive strength, yield strength, shear modulus, and other related parameters obtained by numerical simulation are adopted to determine the optimal representative volume element (RVE) size. Moreover, the effects of microscopic structure characteristics on the mechanical properties of the rock are studied quantitatively. The results indicate that the averaged von Mises stress distribution, displacement field, and plastic strain field of rocks show anisotropy and heterogeneity. The stress concentration and the X-shaped conjugate plastic shear zone are investigated. The samples of S1∼S4 reach the elastic limit and enters the plastic yield state, when the strain is about 0.5%. And the critical yield strain of samples S5300-1∼S5400-2 is about 1%. Then, the quantitative relationships between porosity, TC, tortuosity of rock skeleton and rock mechanics parameters of digital rock samples are established and analyzed. The tortuosity of the rock skeleton is highly correlated with the mechanical parameters of the rock, i.e., Young’s modulus (R2 = 0.95), compressive strength (R2 = 0.94), yield strength (R2 = 0.92), and shear modulus (R2 = 0.94), which is believed to be more feasible to reveal the impacts of the microstructure of the rock on its mechanical properties.

Evolution and Current State of Building Materials, Construction Methods, and Building Regulations in the U.K.: Implications for Sustainable Building Practices

“…Sandstone is a natural material commonly used in historic buildings due to its strength, durability, and non-combustibility. Unlike other natural materials, sandstone can withstand high compressive loads but its compressive strength varies greatly and is dependent on porosity [89,90]. Although sandstone has a high thermal mass, it provides little insulation, so the walls are often very thick to compensate.…”

Study on Long-Term Dynamic Mechanical Properties and Degradation Law of Sandstone under Freeze-Thaw Cycle

“…rough fitting the mechanical parameters of measured sandstone specimens, as shown in Figure 7, uniaxial compressive strength and elastic modulus fitting formulas of sandstone specimens under different freeze-thaw cycles are obtained. Furthermore, the physical and mechanical parameters of sandstone under 150, 200, 250, and 300 freeze-thaw cycles are calculated [21]. A lot of test data show that the density and Poisson's ratio of sandstone specimens are not affected by the freeze-thaw cycle.…”

Characterization and microfabrication of natural porous rocks: From micro-CT imaging and digital rock modelling to micro-3D-printed rock analogs

“…However, it is still a challenge to monitor the sensitivity response of microstructure's evolution on macroscopic properties of geomaterials under laboratory conditions using natural specimens [7][8][9]. Pore-scale modeling based on nondestructive imaging analysis, also known as the digital rock physics (DRP), has been regarded as an efficient approach to obtain petrophysical properties by simulating multiple physical processes [10][11][12][13][14][15][16].…”