Experimental study to enhance prediction of jet-grout column diameter and efficiency in sand

Abstract

One of the most significant factors affecting the efficiency of jet-grouting operation is the diameter of the constructed column, depending on soil properties, stress state and operating parameters, including grout pressure (P), grout flow rate (Q), monitor rotational speed (ω) and lifting step (Δs). Increasing treatment efficiency results in a larger diameter with specific energy applied per unit length of the column. In this study, 35 full-scale and small-scale single-fluid jet-grouting elements were constructed in the field and laboratory to investigate the effects of the operating parameters on the diameter and treatment efficiency of the columns constructed in silty sand. Furthermore, measured values and obtained trends were controlled by a comprehensive equation commonly used to predict the diameter of jet-grouting columns. The results indicate that an increase in the time interval per step (Δt) and grout pressure (P), as well as a decrease in the lifting step (Δs), causes a larger column diameter and lower efficiency. However, a decline in rotational speed (ω) improves both diameter and efficiency. Subsequently, the well-known equation has been modified by considering field measurements in this study to predict more-accurate values and trends for both full-scale and small-scale jet-grouting elements.