Mechanical Properties and Numerical Analyses of Basalt Fiber Crumb Rubber Mortars in Soft Rock Roadways

Abstract

The strength of crumb rubber mortars can be improved by the addition of basalt fibers. However, limited studies have been conducted on basalt fiber crumb rubber mortars (BF-CRM), and the constitutive model is still very immature. In this paper, uniaxial compressive stress-strain curves are obtained for several groups of BF-CRM specimens with different contents. By comparison with the GZH model, modified GZH parameters that can be used in a BF-CRM constitutive model are obtained. Then, taking the support scheme of the main substation of a mine as the background, FLAC3D is used to simulate the roadway support, BF-CRM replaces the ordinary mortars in the original support, and triaxial compression tests are performed at different confining pressures. In this way, the application of BF-CRM in roadway support is studied and analyzed.

Study on Mechanical Properties of the Basalt Fiber-Rubber Granular Concrete under Triaxial Stress Condition and Its Application

“…For A2, B2, C2, and D2, the yield states appeared when the s were about 2-2.5%, while there were no peak strengths in group E. A comparison of the stresscurves in four groups A, B, C, and D indicated that as rubber particle content increased (from A to group D), the peak strengths exhibited a noticeable decrease, and the downtrend of stresse the peak strength became increasingly gentle. In addition, the maximum yield strengths were re when the mass fraction of basalt fiber was 0.4%, which was consistent with the results of the un compression test obtained by Qin et al [27].…”

“…In Figure 4b, the rubber granular concrete B1 was seriously damaged compared to BFRGCs (B2, B3, and B4). Therefore, the addition of basalt fibers could inhibit the development of fractures in both plain concrete and rubber granular concrete, which was consistent with the results under uniaxial compression tests [27]. Moreover, the samples of B2-B4, C2-C4, D2-D4, and E2-E4 had no obvious failure.…”

“…It could be determined from Equation (2) that the yield stresses of A2, B2, C2, and D2 under the uniaxial stress were about 34.55 MPa, 21.64 MPa, 14.58 MPa, and 10.19 MPa, and the residual strengths were about 20.40 MPa, 9.11 MPa, 4.86 MPa, and 3.98 MPa, respectively. Additionally, based on the uniaxial test results [27], the d 0 of A2, B2, C2, and D2 under the uniaxial stress was about 0.23 mm, 0.53 mm, 0.64 mm, and 0.82 mm, and the d 1 was about 0.46 mm, 1.05 mm, 1.27 mm, and 1.63 mm. The derived equations of A2, B2, C2, and D2 are thus given in Equations 3 The Fish function in FLAC3D was carried out to realize the post-peak strain-softening process of the supporting materials.…”

“…The mix proportions of BFRGC were designed based on Qin et al [27] and the "Steel Fiber Concrete Standard Specification" (JGT472-2015) [29]. The results are listed in Table 2.…”

“…Based on the results of the above compression test, the optimum content of basalt fibers in BFRGC was 0.4%; therefore, A2, B2, C2, and D2 were selected to further study the optimal mixing amounts of rubber particles. The σ max and σ min in Equation (1) are determined by fitting the results of the above triaxial test and the uniaxial test obtained by Qin et al [27]. The relationships between confining pressure and yield stress and residual stress are shown in Figure 7, and the corresponding fitting equations are listed in Equation (2 (2) where σ y is the yield stress, MPa; σ 3 is the confining pressure, MPa; σ r is the residual stress, MPa.…”