# Numerical Simulation-Based Study on the Arching Effect in Subsequent Backfill
## 5 Conclusions  
This study systematically investigated the stress distribution characteristics of backfill in complex geological environments using FLAC3D numerical simulations. The main research contents and conclusions are summarized as follows:  
1. By comparing and analyzing the numerical simulation results with and without contact surface elements, the influence of contact surface elements on the stress distribution of the filling body was studied. The research found that the stress at the junction of the filling body and the surrounding rock after considering the contact surface element was greater than that in the model without adding the contact surface element, and the concentration phenomenon was more obvious. Its stress transmission path is more in line with the actual situation. The friction angle between the filling body and the surrounding rock plays a key role in the arching effect, revealing the necessity of adding the contact surface element in the numerical simulation process. In numerical simulation, the contact surface unit of the surrounding rock of the filling body should be added for simulation to obtain accurate results. 2. The influence laws of the parameters of the filling body and the characteristics of the contact surface on the stress distribution were systematically studied. In terms of material parameters: the stress within the filling body is negatively correlated with the friction angle, cohesion, friction angle of the contact surface, and the magnitude of the cohesion of the contact surface. The Poisson's ratio is negatively and positively  
Figure 13: Stress comparison for varied backfill inclinations. correlated with the vertical stress and horizontal stress of the filling body, respectively. The elastic modulus of the filling body has the lowest sensitivity to stress changes. 3. The influence mechanism of the inclination angle of the filling body on the stress distribution was explored in depth. The research results show that as the inclination angle of the filling body increases from 45\({}^{\circ}\) to 90\({}^{\circ}\), its stress distribution presents obvious spatial reconstruction characteristics: the larger the angle between the upper and lower plates of the filling body, the greater is the transfer degree of the compressive and tensile stresses of the filling body to the positions of the bottom plate and top plate of the filling body. Moreover, there are areas within the filling body where the stress received is 0, and the horizontal stress is prone to stress concentration in the middle and upper sections of the filling body. Through systematic numerical simulation analysis in this study, the stress distribution characteristics of the filling body under different working conditions were revealed, providing a scientific basis for the stability evaluation and structural optimization design of the slope. The current research mainly focused on the static filling condition, while in the actual mining process, the geometry of the stope and the stress environment will change dynamically with the advancement of mining. In the future, time-series simulations can be carried out to study the dynamic evolution law of the arching effect under multi-step mining conditions, especially to analyze the influence of repeated mining on the long-term stability of the filling body. In addition, the deep mining environment has complex conditions such as high in situ stress and high osmotic pressure. It is necessary to carry out the multi-field coupling analysis of \"stress-seepage-damage\" to study the differential manifestations of the arch effect under different occurrence environments, providing a more comprehensive theoretical basis for the filling design of deep mines. These research directions will help further improve the theoretical system of filling mining, promote the in-depth transformation of arching effect research results into engineering practice, and provide stronger technical support for the safe and efficient mining of mines. Conceptualization, W.W. and X.X.