In probably the most hard drilling conditions, for example landslide particles, Schnabel has drilled micropiles and made use of them as soldier beams in permanent tieback wall building. A liner of total depth upto really hard rock / strata is necessary. M.S. or HDP pipe liners are being used MS https://jaredfbumd.buyoutblog.com/30541574/the-micropile-for-home-diaries