b'Mechanics of Soil Nail InstallationSoilnailsnotonlylookdifferentfromTorque piles or whales.The soil mass is stabilized byAnchorTiebacks they are designed differently. thematrixofsoilnails,thereforeonly athinItisimportanttounderstandthedramatic shotcrete wall is necessary.differencesintheseproductsbeforeworking Soil nails are installed in a geometrical matrix towith soil nails. distribute the load evenly; and as such, soil nailsForsoilnailstobeeffective,theymusthave are more lightly loaded than tieback anchors.equal diameter helical plates spaced evenly along Some engineers might specify a small seatingthe entire length of shaft. load be applied to the soil nail after installationRememberthatsoilnailsarenottensionedto to remove slack in the couplings; but in generalgain strength; they gain pullout resistance from practice, soil nails are usually not tensioned afterwithintheslidingsoilmassthatislocatedin installationbecausetensioningcanchangethefrontoftheslipplane.Theconceptisrather balance of stresses on the helices.simple to understand.As the unstable soil mass Soilnailingisa passiverestraintsystem,begins to slip downward and outward, the sliding meaningthatthesoilnailsarenotpost-soil creates a force against the back side of the tensioned,theunstablesoilmasshastoslumphelical plates embedded within this moving soil slightly before the soil nail system can developmass.Theforcegeneratedbytheslidingsoil internal forces to resist the soil movements.against these helical plates is resisted on the frontside oftheremaininghelicalplatesthatare Soil nailed walls can be expected to deflect bothembedded within the stable soil behind the slip downward and outward during the slumping ofplane.Figure 5 illustrates the way that the equal thesoilmass. Expectedmovementsofand opposite forces are developed along the Soil approximately1/8ofverticalandhorizontalNail shaft. move-ment of the top of the wall for each fiveThe forces developed within the soil nail system feet of excavation are common.removethestructural needforanexterior Thesemovementsarenormallynotaconcernretaining wall.In most cases the soil nails wall except when an existing structure is situated nearplatesareembeddeddirectlyintotheshotcrete the top of the excavation.The soil overburdencoating.There is no need for sheet piles, H load from a nearby structure can be reduced bySLIP PLANESTABLE SOIL MASS SLUMPINGSOIL MASSREACTION FORCE INTHE PORTION OF THESOIL NAIL EMBEDDEDINTO STABLE SOILREACTION FORCE INSOIL NAIL DUE TOSLUMPING SOILINSTALL ANGLE5 TO 15 DEGREESFigure 5.ECP Helical Torque Anchors Technical Service Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 3 - Page 55 All rights reserved'