Experimental Study Of Deformation And Internal Force Of Soft Pipeline Caused By Subsoil Settlement

With the development of industrialization and urbanization, the construction of underground pipeline developed vigorously. At the same time, more and more destruction accidents of underground pipeline often occur caused by subsoil settlement. In turn, the destruction accidents often cause great economic losses to country and lead to negative social effect. Therefore, it is so much necessary to study pipeline destruction caused by subsoil settlement.In this paper, a series of the lab experiment were conducted to analyze destruction of soft pipeline caused by subsoil settlement. First according to the underground pipeline in Taiyuan city, the process of deformation and destruction of soft pipeline caused by subsoil settlement was simulated and observed in lab through the model test in soil slot. Based on the experimental data, the curve of internal force vs settlement of pipeline is first drawn out and discussed, in turn the characteristic of stress distribution and destruction rule of pipeline are analyzed and summarized. The experimental results show that the pipeline is affected by the settlement of subsoil and the maximum stress section of the soft pipeline is in the hole central section. The stress in the top or bottom of the tube is the highest, the stress at three o’clock and nine o’clock position of the tube are larger. So these positions are of importance for pipeline. The internal force and deflection of the pipeline increase with the depth and width of the hole below the pipeline. When the hole depth (h)/pipeline diameter (D)≥2.5, internal force and deflection change only associate with the width of the hole (b). And when b/D≥6, the pipeline can not work normally and even be destroyed.Second, based on the soil slot experiment, a group of small scale model test was conducted. The following conclusions can be drawn:1. the maximum stress along pipeline appears in the middle of the hole. But the stress in the top of the pipeline is larger than that in the bottom of pipeline. And the axial stress on the pipeline section is larger than the radial stress;2. When the width of the hole changes from0to1D, the stress within pipeline section increases quickly. But the stress reaches maximum when the width of the hole is about3D, in which condition, the pipeline may be destructed;3. When the ratio of pipeline diameter to thickness is same, the tensile stress increases with the diameter decreases. When the pipeline diameter is same, the compressive stress increase, but the tensile stress decreases with the wall thickness increases.