Abstract
It is important to control the injection rate less than the critical injection rate qcr in order to obtain sufficient effects on chemical grouting, qcr is the maximum permissible injection rate to make good solidified shapes, qcr is determined with the relation between injection pressure p and injection rate q (p-q curve) of the standard water injection test. But for several causes on measurement, qcr based on p-q curves of injection sites must be often modified. This paper investigates the improvement of method of determining correct qcr. And the authors suggest that the ratio of p10 (at q=10l/min) and p2 (at q=2l/min) calculated with p-q curve is useful for deter-mining correct qcr easily.The relation between qcr and p10/p2 value is follows: qcr=10(p10/p2) -10
