Basic soil testing book that emphasizes the basic principles of soil mechnics using spreadsheet data processing. The book includes soil laboratory experiments, and discussion of the theoretical concepts needed to interpret the experimental results.

The field of experimental unsaturated soil mechanics has grown considerably over the last decade. In the laboratory and in the field, innovative techniques have been introduced into mechanical, hydraulic, and geo-environmental testing. Normally, this information is widely dispersed throughout journals and conference proceedings and it is often difficult to identify suitable equipment and instrumentation for research or professional purposes. In this volume, however, the authors bring together the latest research in laboratory and field testing techniques, and the equipment employed, and examine the current state-of-the-art in a forum devoted solely to experimental unsaturated soil mechanics. The papers published in the proceedings were peer-reviewed by internationally-recognized researchers. The topics tackled by the papers include suction measurement, suction control, mechanical and hydraulic laboratory testing, geo-environmental testing, and field-testing.

Unsaturated soil mechanics is now increasingly recognized as an integral part of mainstream soil mechanics, and the importance and relevance of unsaturated soil mechanics for the broad field of geotechnical engineering no longer needs to be emphasized. The two volumes making up Unsaturated soils include papers from the 4th Asia Pacific Confere

These proceedings document the various papers delivered and partially presented at the International Conference “From experimental evidence towards numerical modeling of unsaturated soils,” which was held in Weimar (Germany) during 18-19 September 2003. The conference was organized under the auspices of the International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE) and the National German G- technical Society (DGGT). The need to understand the behavior of unsaturated soils is becoming exclusively - sential for the geotechnical engineers and designers. In the last three decades many - searchers have made significant contribution to the understanding of the unsaturated soil mechanics. Nevertheless, application of the subject to variety of new problems still - quires our attention. This International conference is a mere attempt to unite researchers and engineers in geotechnical engineering and to discuss about the problems associated with the unsaturated soils. Doing so the objectives of these lecture notes are as follows: - to promote unsaturated soil mechanics for practical application, - to exchange experiences in experimental unsaturated soil mechanics and numerical modeling, - to discuss application of unsaturated soil mechanics to variety of problems. In other words, we could also name these two volumes as “From theory to daily pr- tice”. I would like to extend my deep sense of appreciation as the editor and the Head of the organizing committee, to many persons who have contributed either directly or indirectly to organize the International conference and to finalize these proceedings.

This work presents the experimental results of the strength of sands and clay soils in the following conditions: plane shear, triaxial stress state, with passive and active loading. The obtained experimental results are compared with existing theories of strength and the reasons for their non-conformity are identified. Experimental data on the determination of the position of shear surfaces with active and passive resistance of soils is analysed. A new concept of the theory of soil strength is considered, which allows to take into account the fundamental parameters of the strength of soils: the angle of internal friction, specific adhesion, and lateral pressure ratio. Given analytical expressions allow one to determine the stress state at the sites rejected with respect to the main stresses. The definition of the physical essence of the concept of lateral pressure coefficient for soils is given. Also described are the results of experiments to determine the critical load on soil having the shape of a truncated cone, where the angles of deflection of the shear surfaces have been experimentally determined, on the basis of which analytical expressions have been obtained that allow prediction of the critical load. The book provides methods for solving various geotechnical problems using the theory of soil strength proposed by the authors. The book is intended for professionals working in the fields of soil mechanics and geotechnics, as well as for students and academics in engineering, earth and soil sciences and construction.