b'mustbeusedasbackfillagainstthewallafter engineeringassistanceforwallstallerthan12restorationalongwithapropergroundwater feet and/or more complicated projects.drainage system for stability. HydrostaticPressure: IfwaterispresentorThewallwillalwaysbeexposedtoactive suspectedbehind abasementorretainingwall,pressurefromthesoilandpossiblehydraulic theadditionalforceofthehydrostaticpressureforce from water. For the Torque Anchor to mustbeaddedtotheloadrequirementsof theproperlydevelopresistanceagainstthisactive tieback anchor.pressure,theanchormustbeinstalledbeyondthis active soil area. Once beyond this area, the Whensoiland/orsubsurfaceconditionsaretiebackcandeveloppassiveearthpressure unknown, it MUST be assumed in the designagainstthehelicalplate(s).Figure3,above, that water pressure is present.showsthegenerallayoutforatiebackproject Basement Tieback Applications: If a basementanddesignelementsfor theembedmentofthe wallfailsbecauseofinsufficientstructuralhelical plates for proper support. integrity,improperfillagainstthewalland/orItismostimportantthatanybasementwall improper compaction of the fill, then Equation 4repair include an investigation, and any remedial maybeusedforapproximatingtheloadperworkrequiredtoprevent anyfutureconditions linealfootagainstthebasementwall. Thiswherethesoilbehindthewallcanbecome equation assumes that no hydrostatic pressure issaturated.Ifthedrainageworkisnot present. Please refer to Figures 3 & 4.accomplishedimmediatelyfollowingtiebackinstallation,thedesignmustassumethatthere Equation 4:Basement Wall Loadwill be hydraulic pressure against the wall.An P HM= 18 x (H 2 ) (Moist - No Water Pressure)engineer can determine if the wall has sufficientstructuralintegritytosupportthesecombined When water pressure is present behind theloadsifdrainagecorrectionsarenot basement wall or if it is not known if hydrostaticimplemented. pressure exists, Equation 5 should always beDesignofretainingwallsisverycomplicated used to estimate the load.and requires engineering input.This manual hasgreatly simplified the equations so that the reader Equation 5: Basement Wall Loadcanquicklyandrelativelyeasilyobtainan P HS= 45 x (H 2 ) (Saturated - Water is Present)estimateofthereactionforcerequiredtostabilizeandsupportafailingretainingwall. Where:Thismaterialshouldbeusedwithcautionfor P HS= Saturated Soil Load on Wall - (lb/lineal foot)newconstructionretainingwallsorbasement H = Height of Backfill - (ft)wall designs. Simple Retaining Wall Tieback Applications:Placement of Tiebacks: The vertical placement Similarly,ifaretainingwallfailsbecauseofof the tieback is dictated by the height of the soil insufficientstructuralcapacity,improperfillagainstthewall.Itisrecommendedthatthetiebackbeinstalledclosetothepointofmaximum bulging of the wall and/or close to themost severe horizontal crack in the wall.Whenthewallisconstructedofblocks,orwhereaconcrete wall is severely distressed, vertical steel T Usupports and/or horizontal waler beams must beTIEBACKused to provide even distribution of the reaction PLACEMENTforce of the anchor across the face of the wall. 0.2H TO 0.6H SOILP H HEIGHTThetypicalverticalmountinglocationfor"H"tieback anchors is 20% to 50% of the distancedown from the elevation where the soil touchesdown to the wall to the bottom of the wall.Seek (EQUATIONS4 OR 5)Figure 4. Basement Tieback ApplicationECP Helical Torque Anchors Technical Service Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 1 - Page 30 All rights reserve'