Energy and deformation field evolution characteristics of layered cemented paste backfill under cyclic loading and unloading

Abstract

Due to the mining environment, layered cemented paste backfill (LCPB) is usually subjected to the cyclic pressure. Therefore, it is of great significance to investigate the mechanical behavior, failure mode and energy evolution characteristics. LCPB samples were prepared and subjected to constant lower limit cyclic loading and unloading test. The digital image correlation (DIC) technology was applied to monitor deformation field of LCPB. The obtained results indicate that: (1) The area of the hysteresis loops increases sequentially with increasing unloading stress level, while the spacing between the hysteresis loops gradually increases, showing the typical “dense-sparse” two-stage variation law. (2) Energy density and the unloading stress level is in agreement with the power function. The limiting elastic energy density (uemax) shows a linear decrease with the increase of h. The exponential function can well characterize the quantitative relationship between uemax and c/t ratio. (3) The damage mode of LCPB gradually tends to x-shape shear-dominated damage with the increase of h. The damage mode of LCPB is gradually dominated by shear-type damage with the decrease of c/t ratio. Ultimately, the findings of this work can provide a reference for the design of LCPB.