AN INTRODUCTION TO ALLUVIAL GROUTING.

THE Paper describest he general principles of the "single fluid" injection process with examples of its application in civil engineering, with particular reference to the treatment of alluvial deposits. The nature of alluvial deposits, the physics of injection and various types of grout are discussed at some length since all have an important bearing on the economics of most grouting operations. A description of the tube 5 manchette precedes an outline of the control of injection with the emphasis on site investigation and trial blocks. Grouting alluvial soils may be used as a temporary expedient in large excavations, such as Vogelgrun Power Station on the Grand Canal Alsace, in deep basements in cities and in shaft sinking in fine sand. The use of alluvial grouting for tunnels is mentioned, with references to the Dartford-Purfleet tunnel, the Clyde tunnel and the new Blackwall tunnel under the Thames. To form impermeable cut-offs beneath dams, grouting has been used by itself or in combination with bored sheet piles. Grouting may also be used to repair such sub-surface structures as tunnels and concrete and masonry foundations.