SOME RECENT DEVELOPMENTS IN SITE INVESTIGATION PRACTICES

The paper describes the development and use of several in situ testing techniques for site investigations currently employed by the Country Roads Board of Victoria. The enhancement over recent years of in situ devices such as the penetrometer and pressuremeter has largely resulted from the need for more reliable determinations of geotechnical design parameters for use in theoretical modelling techniques. The paper firstly describes the current methods of interpretation and use by the Board of the quasi-static electrical penetrometer. Considerable cost savings have resulted from the use of the penetrometer by the Board since the mid-1970's to minimise costly investigation drilling and sampling during site investigations for highway structures. Examples of its use that are described are the identification of soil types and the prediction of load capacity of driven piles. Also described are several examples of pressuremeter testing, using both the borehole and self-boring devices. Although there is need to refine the measurement of soil strength and deformation values using pressuremeter results by comparing those indicated by appropriate laboratory and full-scale field tests, the device has potential for economical and reproduceable in situ measurement. Examples described include elastic modulus determinations and the measurement of in situ horizontal ground stresses. (Author/TRRL)