Volume 33, Issue 5 (September 2010)
Large Scale Laboratory Testing of Low Mobility Compaction Grouts for Drilled Shaft Tips
While post grouting of drilled shaft tips is an acknowledged means of mobilizing shaft base resistance at low values of displacement, much uncertainty exists among engineering professionals as to the conditions under which this option may be entertained. The impact of diverse factors such as soil gradation and soil relative density, overburden pressures, and grouting methods utilized needs to be properly understood. This paper details the laboratory test set-up utilized by researchers toward studying the impact of such factors on post grouting and resultant shaft base capacity increase. The focus of this paper is on the different components of the test set-up considered during the design and implementation stage. Several unique aspects dealt with as a part of this study and elaborated on herein include the testing chamber dimensions, method of overburden pressure application, soil deposition technique, grouting methodology employed for the low mobility compaction grout utilized, load testing protocol, and instrumentation. Sample test results included indicate satisfactory load resistance increase through grouting with a low mobility compaction grout. The performance of this set-up during the testing phase indicated applicability for use in large scale laboratory testing of low mobility grouts and drilled shaft foundations.