Mechanical properties and deformation mechanism of stratified cemented tailings backfill under unconfined compression

Abstract

Studying the deformation mechanism of stratified cemented tailings backfill (SCTB) is of great significance to determining the reasonable strength of the backfill and reducing the filling cost. In this study, the SCTB samples with 0,1,2,3, and 4 stratified surfaces are prepared. Mechanical tests were carried out on the samples, in which the digital image correlation method and scanning electron microscopy (SEM) analyses were conducted on the layered backfill samples. The findings indicated that the existence of stratified surfaces causes a significant deterioration in the uniaxial compressive strength and elastic modulus of the SCTBs, but increases its deformation capacity. During the loading process of the SCTBs, the stratified surfaces always present a compressed state and the average strain of the SCTBs is greatly affected by the stratified surfaces. The macro–micro-cracks at the stratified surfaces could be divided into two types: cracks passing through the stratified surfaces (CPSSs) and cracks not passing through the stratified surfaces (CNPSSs). The SEM results indicated that there was a greater abundance of CNPSSs than CPSSs, meaning the stratified surfaces inhibited the propagation of micro-cracks. With the increase of the number of stratified surfaces in SCTBs, the stratified surfaces compression displacement (SSCD) of a pair of stratified surfaces decreases.