Defining the soil parameters for computing deformations caused by braced excavation

Abstract

Evaluation of the soil response is required to estimate the potential building damage caused by excavations. Using proper soil parameters is a key ingredient when computing soil responses, assuming the model represents the actual soil response in a reasonable way. Soil parameters are usually identified from laboratory experiments performed on tube samples or from in situ tests, but large uncertainties are associated with these methods for most projects. Inverse analysis is a quantitative technique that allows one to select parameters to fit the responses of soil from both laboratory tests and field observations. The technique is applied to results of both the laboratory experiments on block and thin-walled tube samples and the field performance data, all of which were collected from an excavation made through Chicago clays. The results of computed soil responses based on the hardening soil (HS) model and the hardening soil with small strain (HSS) model found in the computer code Plaxis are compared to illustrate the problems that are likely to be encountered in practical application of finite element simulations. Guidance is provided for selecting the parameters from laboratory tests to compute the field responses for braced excavation loadings.