Staged Construction Modeling of Steel Pipes Buried in Controlled Low-Strength Material Using 3D Nonlinear Finite-Element Analysis

Several complexities are inherent in numerical simulation of staged construction modeling of large-diameter steel pressure pipes. A comprehensive robust three-dimensional (3D) nonlinear finite-element analysis model was developed and verified using three experimental field tests conducted at the Rolling Hills Booster Pump Station, Fort Worth, Texas, to simulate the behavior of buried steel pipes during staged construction installation. Controlled low-strength material (CLSM) was used as the embedment material, and the depth of the CLSM embedment and the trench width varied. The developed numerical model includes three possible nonlinearities, including geometric, material, and contact nonlinear algorithms. A large deformation algorithm was considered in the finite-element model and its associated analysis using a total Lagrangian formulation. The contact between each soil layer, soil-to-trench wall, and soil to pipe was carefully implemented. The lateral effect of compaction was identified in previous studies for the soil box test (rigid trench wall), and uniform thermal loading was applied to simulate the stresses induced because of compaction forces on the pipe and trench walls. A formula was derived using mechanics of material formulations to identify the required temperature for the various embedment configurations. Finally, the vertical and lateral load deformations and strain plots obtained from the finite-element analysis results were compared with the full-scale experimental test results during the staged construction process and after the application of surcharge load. The results of the finite-element analysis accurately modeled and simulated the test results. (C) 2014 American Society of Civil Engineers.