Abstract: Chute spacing critically determines the magnitude and distribution of dynamic lateral pressure on silo walls during single-sidewall discharge. However, systematic research on how chute spacing affects the flow behavior of stored granular materials and the resulting dynamic wall pressure is still scarce. To fill this gap, this study systematically investigates how chute spacing influences dynamic lateral pressure and its associated reduction mechanism. This is achieved by integrating physical model experiments, discrete element method (DEM) simulations using PFC, and theoretical analysis. Discharge tests were performed on a laboratory-scale single-sidewall discharge silo. This silo was equipped with chutes having a fixed width of 0.05 m but three different spacings: 0.03 m (sp3), 0.04 m (sp4), and 0.05 m (sp5). During the tests, an array of pressure sensors continuously monitored and recorded the dynamic lateral pressure on the silo wall in real time. Simultaneously, a video camera captured the macroscopic flow state of the stored material, which was soybeans. Using the validated PFC discrete element model, the study further analyzed the microscopic mechanisms governing the discharge process. These mechanisms include particle trajectories, the spatial and temporal evolution of force chain networks, and the formation and collapse of local pressure arches under different chute spacing conditions. Based on these analyses, the mesoscopic flow characteristics of the stored material and the variation patterns of dynamic lateral pressure on the silo wall were systematically examined and correlated.The experimental results show that chute spacing significantly affects both the flow regime of the stored material and the peak dynamic lateral pressure. Compared with the sp3 and sp5 conditions, the sp4 configuration produces the lowest peak dynamic lateral pressure on the silo wall. This reduction is approximately 10%. Specifically, under the sp4 condition, the stored material exhibits a stable and well-organized stratified flow pattern throughout the entire discharge process. This stable stratified flow effectively suppresses the formation and persistence of local pressure arches near the discharge outlet. These arches are known to be the primary sources of intense dynamic pressure pulses. Consequently, the dynamic impact of grain particles on the silo wall during discharge is significantly weakened and more uniformly dispersed. In contrast, under the sp3 condition (smaller spacing), the stored material frequently undergoes alternating arching and collapsing. This leads to pronounced fluctuations in dynamic lateral pressure. Under the sp5 condition (larger spacing), the flow tends to concentrate through the lower chutes. This creates a pronounced pipe flow effect and material accumulation near the outlet, which in turn raises the peak dynamic pressure.In addition to the experimental and numerical investigations, a theoretical analysis was conducted. This analysis mechanically isolated an idealized grain body above the chute array and established force equilibrium equations. This analysis derives a theoretical optimal chute spacing of approximately 0.04 m. This value agrees remarkably well with the experimental and simulation results. Therefore, when the chute width is fixed at 0.05 m, the optimal chute spacing is determined to be 0.04 m. This optimal spacing effectively promotes stratified flow of the stored material and inhibits the formation and development of pressure arches. In doing so, it significantly reduces the dynamic lateral pressure exerted on the silo wall. The integrated experimental, numerical, and theoretical findings provide a solid scientific basis and a practical reference for the structural optimization design of silos equipped with sidewall discharge chutes. These contributions lead to safer and more efficient grain storage and handling systems.