Size effect of parallel-joint spacing on uniaxial compressive strength of rock

Abstract

The existence of parallel joints has an impact on the size effect of the uniaxial compressive strength of rock, but the relationship is yet to be obtained. In this paper, the influence of parallel-joint spacing on the size effect and characteristic size of rock uniaxial compressive strength is studied by establishing five types of parallel-joint-spacing simulation schemes. The influence of parallel-joint spacing on the size effect of rock uniaxial compressive strength is explored by analyzing the stress–strain curves of rocks with different parallel-joint spacings and rock sizes. The relationship between the uniaxial compressive strength and the size of the rock with parallel joints and its special mathematical model are obtained, and the particular form of the compressive-strength characteristic size and parallel-joint spacing is obtained.

Influence of Parallel Joint Spacing and Rock Size on Rock Bulk Modulus

“…As seen, the compressive strength of the rock gradually decreased with the increase of the rock size from 100 mm to 1,200 mm, thereby somewhat manifesting the size effect. Notably, the law of the curve is consistent with the law from [15], thereby indicating that the size effect of the rock was the same when the parameters of the joints changed.…”

“…K(s) � 1.241sl − 0.833 + 381.501l − 1.272 . (15) Moreover, the relationship between K and rock size is exponential:…”

“…is study primarily focuses on two aspects: (1) elucidating the influence of PJS on rock K, with PJS of 10, 20, 30, 40, and 50 mm and (2) elucidating the effect of rock size with PJS on rock K, with the rock sizes of 100, 200, 400, 600, 800, 1,000, and 1,200 mm. Table 1 summarizes the research plans of this study based on [15]. is study uses RFPA as the simulation software.…”

“…is study uses RFPA as the simulation software. e boundary conditions and rock mechanical parameters used in the numerical simulation are summarized in referred to [15]. e roughness coefficient of the joint applied for the numerical simulations was 3, its elastic modulus was 1.5 MPa, its compressive strength was 2 MPa, its Poisson's ratio was 0.3, and its internal friction angle was 30 °.…”

“…e mechanical parameters of rocks fundamentally vary with the size of the jointed rock and eventually tend toward a stable value, which is defined as the representative essential volume (REV). Some researchers have previously proposed various methods to evaluate the REV, whereas Hu and Ma [15] used a realistic failure process analysis (RFPA) to study the characteristic size. Ying et al [16] established a method based on volume rupture strength (P32) and a statistical test method to estimate rock mass REV.…”