Settlement prediction of undercrossing semicircular tunnel-pile set up in soft clay soil

The Earth Pressure Balance (EPB) tunnel boring in combination of piling and sequential excavation method (SEM) is used to discuss the influence of piled tunnel lining that under crosses an existing tunnel along the Zhongshan Road. Soil investigation data and numerical simulation was applied to analyze the model. The Mohr -Coulomb (MC) model in MIDAS GTS NX software is used to simulate the settlement levels of semicircular tunnel lining and soil against various pile set ups in order to obtain the best set up for ground improvement. Results indicate a substantial variation in vertical settlement. The. designed 5x4 pile set up has the highest crown settlement but optimal lining uplift control by 138–165% while substantially increasing crown displacement by 32–47%. The 4x4 pile performs all-round by reducing uplift by 184–194% and less volatile settlement by -12% to -47% to within 5-10mm. The 4x4 pile is more reliable and less volatile in both settlement and uplift. Uniform pile set provides a better settlement trough than non-uniform pile setups. Proposed formulas based on Gaussian function reliably uses n and k parameters to predict settlement for greenfield conditions and project behavior for tunnel undercrossings. The green field prediction function is verified using 12 existing projects and n values are estimated at \(n \pm 1.4\) prediction while back-calculation gives values close to known settlements.