Penetration Grouting Research Articles

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.

Grouting in Difficult Soil and Weather Conditions

Several methods of soil grouting and conventional underpinning are used to stabilize subsoils and repair the foundations of three apartment buildings. Innovative cold weather compaction grouting techniques were used in difficult soil conditions to densify poorly compacted man‐placed fill and soft organic silts beneath building foundations. Penetration grouting using a Portland cement slurry and Pozzolan (flyash) is performed to reduce permeability of the upper subsoils and to fill ineffective and detrimental building perimeter drains. A gravel intrusion jacking method is used to further density upper soils in conjunction with conventional underpinning methods. The project is unique because: (1) Techniques were used that allowed the contractor to drill and densify loose fills and soft natural soils containing cobbles and boulders; (2) the contractor was able to perform grouting and underpinning under extremely adverse weather conditions by using special equipment; and (3) occupants were able to remain in buildings during remedial construction.