Effects of Soil Deposition on the Initial Stress State in Model Tests: Experimental Results and FE Simulation

Abstract

The knowledge of the initial soil state (stress and density distribution) in geotechnical model tests is indispensable, particularly with regard to FE back calculation of experimental results. Usually, so-called K 0 -conditions are assumed, which for many cases do not describe the soil stress state before the experiment begins adequately. Using an exemplary test device we present and discuss different measurement techniques for the interpretation of soil deposition procedures and the evaluation of the initial state. By means of stress and bearing force measurements, the stress state is captured representatively. The soil deformations during the filling of the test device are evaluated with Digital Image Correlation (DIC) methods and the initial density distribution is examined by cone penetration tests (CPT). Afterwards, a simple FE simulation method is presented, which models the soil deposition procedure by a weight increase layer-by-layer. It is shown that the method is suitable to provide a realistic initial soil state. The methods presented can be easily transferred to other geotechnical test devices and can in many cases ensure a better comparability of tests with their simulations.

On Soil Deformation and Stress Redistribution Around Pressed-in and Vibrated Displacement Pile Tips

“…The glass windows have relatively smooth surfaces and are reinforced horizontally. This experimental setup tries to achieve plane-strain conditions (which is actually not completely successfull, see [13] and Sect. 6.2).…”

“…Note that the initial stress state before the test is influenced by silo effects. An investigation of these effects is provided in [13].…”

“…Before the test, the uniformity of the soil sample is controlled by CPTs. The set-up, evaluation procedure and first results are discussed in [13].…”