Analytical and numerical modeling of pullout capacity and interaction between hexagonal wire mesh and silty sand backfill under an in-soil pullout test

During the pullout test, the pullout clamping system was modified and installed inside the pullout box with confinement from the fill material, hereinafter called the in-soil pullout test, which significantly reduced the necking phenomenon and the displacements mobilized during the pullout test. Subsequently, an analytical model was developed to predict the in-soil pullout resistance. In addition, a numerical modeling analysis, under the three-dimensional stress field conditions using the FLAC(3D) (fast Lagrangian analysis continua) program, was carried out to simulate the behavior of in-soil pullout tests. The laboratory in-soil pullout test results were then compared with the corresponding data obtained from the analytical and numerical modeling methods. The in-soil pullout resistance was greater than the corresponding result from previous pullout tests wherein the clamping system was conventionally installed outside the pullout box. The predicted pullout resistance results from FLAC(3D) agreed reasonably with the results from laboratory tests and with the results from the analytical modeling. The interaction coefficients, R, applied in the finite difference modeling of in-soil pullout tests were 0.90 and 0.65 for zinc-coated and polyvinyl chloride (PVC) coated hexagonal wire meshes, respectively. The predicted and measured pullout resistance of zinc-coated hexagonal wire mesh is approximately 20% greater than that of PVC-coated hexagonal wire mesh at the same applied normal pressure, because of the higher stiffness, EA, and higher shear stiffness, k(s), of the zinc-coated mesh.