Study on the influence of contact surface characteristics on strength and fracture evolution of layered cemented backfill (LCB)

• Published in: Case Studies in Construction Materials 2024-07, Vol.20, p.e03264, Article e03264
• Main Authors: Zhang, Shengyou, Sun, Wei, Hou, Zhengmeng, Wu, Aixiang, Wang, Shaoyong
• Format: Article
• Language: English
• Subjects: Failure mode; Fracture evolution mechanism; Layered cemented backfill; Optimization of filling ratio; Surface fitting; Uniaxial compressive strength
• ISSN: 2214-5095; 2214-5095
• DOI: 10.1016/j.cscm.2024.e03264

The stability of backfill plays a crucial role in the process of mine operation. In this study, author combined indoor experiments, surface fitting, numerical simulation, and theoretical derivation to investigate how the filling times (FTs), cement tailings ratio (CTR), and minimum CTR filling position (MCFP) affect the uniaxial compressive strength (UCS) and fracture evolution behavior of LCB. The findings demonstrate that an augmentation in FTs reduces the UCS of LCB. Moreover, the highest strength ratio resulting from diverse MCFP amounts to 2.25 times. When once filling, backfill sustain damage as a result of cracks penetrating, whereas LCB that are filled multiple times first encounter damage at the layered contact surface, followed by the gradual spread of cracks until penetrate the LCB. Through an interactive regression model, it is evident that FTs, CTR, and MCFP significantly affect the UCS. Additionally, the interaction between CTR and MCFP has a considerable impact on the UCS. Based on numerical simulation, an increase in FTs results in a wider large displacement area generated by the backfill, leading to greater horizontal and vertical displacement. The MCFP has a significant impact on the lateral displacement and maximum stress of the backfill. Theoretical derivation verifies that MCFP at the top or middle layer results in an increase in the UCS, which is consistent with the experimental findings and numerical simulation. This paper elaborates on the mechanical mechanism behind the interaction between CTR and MCFP. These findings can provide a foundation for assessing the durability and stability of LCB in subsequent stages. [Display omitted] •The variation law of UCS of the backfill caused by the FTs and the MCFP has been studied.•The effects of FTs and MCFP on fracture development in LCB were analyzed.•The surface fitting of LCB by FTs, CTR and MCFP was studied.•The effects of FTs and MCFP on the X and Z displacement, and maximum principal stress of the LCB have been studied.•Through theoretical derivation, the influence model of layered contact surface strength of LCB was established.