MATHEMATICAL-MODEL FOR BORE-INJECTED CEMENT GROUT INSTALLATIONS

There are many geotechnical engineering support systems (for example, bore-injected minipiles, grouted anchors, grout in the void around a t unnel liner) where it is advantageous to inject a cement grout under p ressure. A mathematical model is developed in this paper for the physi cal process that occurs as the grout consolidates (similar to a clay s oil) under the applied pressure and expels its excess water into the s urrounding soil under conditions of impeded drainage. The model is the n used to calculate such parameters as the average degree of consolida tion of the grout as a function of time prior to set and the change in the borehole radius. A series of specially designed experiments for a variety of conditions provide data that compare favorably with the th eoretical predictions and thus lend credibility to the usefulness of t he mathematical model for characterizing the physical situation that o ccurs during such operations in the field.