Numerical and experimental analysis of penetration grouting in jointed rock masses

The reinforcement effect of penetration (or permeation) cement grouting injected into jointed rock masses is investigated in this paper. For this, anisotropic material properties of jointed rock masses with and without grouting are derived based on the mechanics of composite material. Derived anisotropic material properties are not only functions of the material properties of the intact rock and grouting, but are also related to the geometric and mechanical properties of rock joints, such as dip angle, spacing and stiffness. Two in situ seismic tests were also performed to obtain information on the ground improvement. Finally, a back analysis methodology is proposed to quantify the reinforcement effect. Here, joint stiffnesses of the rock masses are selected as the dominant parameter to be determined. The so-called back analysis shows that, after grouting, the stiffnesses of the filled joints are increased upto 6 times compared with those of the ungrouted joints. (C) 2000 Elsevier Science Ltd. All rights reserved.