Analyzing the Effects of Gaining and Losing Ground

There are many problems in geotechnical engineering where the inadvertent or controlled ground loss or displacement of soil have important implications in geotechnical design. This paper shows that simplified analytical methods can provide reliable and practical solutions for estimating ground movements in two applications: Analyses of pile installation using the Shallow Strain Path Method simulates consistently the downward movement of soil beneath the advancing pile tip and the more general heave towards the stress-free ground surface. Far field movements can be estimated using simple closed-form solutions. Field monitoring data from a large piling project in East Boston provide a clear demonstration of the predictive capabilities of these analyses. Tunneling-induced ground movements can be obtained by similar approximate techniques, considering deformations around the tunnel cavity as the sum of three component mode shapes. Analytic solutions have been obtained for 2D deformations around a cylindrical tunnel cavity using assumptions of linear elastic and constant plastic flow behavior. Examples presented in the paper show that the analytical solutions are not only consistent with well established empirical methods, but also provide a more comprehensive framework for understanding the distribution of ground movements.