Geotechnical Engineering Online Library

In arid to semi-arid regions alluvial soil deposits can range from collapse-susceptible, variably cemented to indurated. In these soils, reliable estimation of soil properties based on penetration resistance indicators such as N-values from Standard Penetration Tests (SPTs) is difficult. Varying content of gravels and cobbles provides additional complexity. In such conditions, sample recovery from SPTs is limited and refusal N-values occur. This paper presents a database of 74 pressuremeter tests along portions of Interstate 10 (I10) through Tucson, Arizona, where soil conditions noted above were encountered. The results are used to evaluate the subsurface stratigraphy. Estimated side and base resistance for drilled shafts are presented and compared with recommendations by the American Association of State Highway and Transportation Officials (AASHTO) and the Federal Highway Administration (FHWA). Comparisons of estimated side and base resistances from pressuremeter tests with those from a large-scale load test are presented. Evaluation of the collapse potential of soils using pressuremeter tests is also discussed and the results compared with collapse potential based on 1-D laboratory tests.

The collapse of the soil structure due to wetting is called hydroconsolidation and it occurs only once under constant loading, in cases of perturbation of the soils moisture content. It is encountered usually in non-sedimentary soils such as anthropogenic fills and residual materials. This paper presents an interpretation of hydroconsolidation settlements in a building of the historical centre of Thessaloniki followed after a rise of the water table. The interpretation is based on the results of laboratory evaluation of hydroconsolidation properties, in conjunction with in situ measurements of settlements.

A 30-m long railroad embankment failure that occurred on May 25 2011 in the city of Ann Arbor, Michigan, is presented. Emphasis is given on the field observations of the failure, the characterization of the site conditions and the seepage and slope stability analyses, all of which represent important components of the training and practice of a geotechnical engineer. The failure occurred following a record wet season that resulted in ponding water against the embankment and high enough water pressures and exit gradients that resulted in instability of the railroad embankment. Detailed background material and the methodology for using the case history in geotechnical engineering education are presented.