Stress measurement in partially saturated soils and its application to physical modeling of tunnel excavation

Abstract

The capacity of a commercially available miniature pressure sensor for measuring stress evolutions in a partially saturated soil under quasi-static loads is studied, in view of its later application in laboratory-scale physical models. An extensive calibration program is first performed on a triaxial cell under isotropic loadings. These calibration tests provide useful data for assessing the uncertainty in stress measurements, especially in the case of partially saturated granular materials. Notably, influences of soil density, water content, and average grain size on stress measurements are quantified. Following these tests, an example of stress measurements on an original reduced-scale model of “earth pressure balance shield” (EPBS) is presented, which involves three-dimensional arching effects developing around the shield during excavation.