Multifactor sensitivity numerical simulation analysis of mechanical behavior characteristics of reinforced concrete drainage pipeline under three-edge bearing test

The three-edge bearing test (TEBT) is a crucial means of conducting mechanical performance tests and assessing the mechanical properties of concrete pipelines. This study analyzes the failure process, load-bearing capacity, and circumferential strain of concrete pipelines while comparing the numerical simulation results of three constitutive models. The outcomes demonstrate that the strain curve trends within the tensile and compressive regions of concrete can be deduced by examining variations in the slope of the damage factor curve, and the numerical simulation results obtained from the constitutive model based on the equivalent energy method of uniaxial stress curve exhibit remarkable accuracy, it achieves a maximum deviation of 12.03% in compressive damage factors and 40.2% in tensile damage factors compared to other models. Moreover, the present research reveals that different loading beam or buffer rubber configurations during the loading process can result in distinct stress areas within the pipeline, where larger loading areas lead to an earlier critical bearing capacity for rapid crack propagation within the tensile zone of the pipeline. Quantitative analysis shows that line loads induce 18.7% higher peak stress at the pipe crown compared to area loads, but exhibit 37.2% faster stress attenuation from crown to waist (e.g., 82.83% residual strain under area load vs 67.45% under line load at waist position for 1.5 m-diameter pipes). Although the stress induced by area loads is 23.4% lower than that caused by line loads at the crown, its attenuation rate within the pipeline is 41.6% slower, particularly evident in smaller-diameter pipes where area load-induced stress maintains 74.3% of initial value at 1/2 pipe length versus 58.9% for line loads. Finally, an improved stirrup arrangement design is proposed to enhance the crack resistance of reinforced concrete drainage pipes while simultaneously reducing material costs, the improved stirrup arrangement reduces concrete strain by 37.14% in 1 m-diameter pipes while saving 50% of steel material, achieving optimal cost-performance balance for small-diameter pipelines.