Prospective method to estimate shear stress in the ground using two earth pressure cells

Many sophisticated numerical methods have been developed to evaluate soil responses. However, the lack of referential stress–strain behavior under complicated in-situ ground conditions makes it difficult to validate the obtained responses sufficiently. For example, under a long embankment, with imposing plane strain conditions in depth, allowing for both horizontal displacement toward the slope toe and settlement, the stress components change as a result of the interaction between one soil part and adjacent soil parts. Since those stress conditions themselves are unknown, no laboratory experimental data can be provided to validate a constitutive model. Therefore, the author considered that studying the stress conditions in the ground would play an important role in confirming the calculated results obtained by a numerical method. Soil stress cells have sometimes been utilized to measure the earth pressure in an experimental model, but such measurements have often proven to be unreliable or unrealistic. However, the preciseness of earth pressure meters has recently been examined and improved. Recently, centrifuge tests were conducted to estimate the shear stress in a horizontally layered model ground during shaking. By using a pair of earth pressure meters and the concept of Mohr’s stress circle, it was possible to estimate the shear stress at any point in the ground. The shear stress estimated by this method was seen to agree well with the results obtained by a calculation based on the force balances of the supposed soil blocks from the ground surface. As a result, it was confirmed that the proposed method is a promising way to estimate the shear stress in the ground and is worthy of further investigation.