9.2.2 Packers

In order to maintain grouting pressures and control where the grout is injected into the ground，tight“seals”must be utilized.These seals may be mechanically tightened where the grout hole meets the insertion pipe，or against the pipe wall or hole at a desired depth（downhole packers）.Balloon packers are generally hydraulically or pneumatically inflated membranes，which provide a seal above and／or below a grout injection point to control the injection location within a grout hole or grout pipe location.Use of multiple packers may be desirable to isolate the injection point to specific subsurface horizon（s）.