b'against the wall and/or consolidation of the fill, Equation 8: Ultimate Tieback Capacitythen Equation 6 may be used to approximate the T U= (P H ) x (X) x FSload per lineal foot of retaining wall.If the soilat the top of the wall is level as shown in Figure Where:5,thenthevalueofSinEquations6&7 T U= Ultimate Tieback Capacity Tension(lb)becomes zero. This equation assumes that no P H= Foundation Load or Force on Wall(lb/lin.ft)hydrostaticpressurepresent.(Referto FS = Factor of Safety (Typically 2.0 - PermanentFigures 3 and 5.) Walls and 1.5 for Temporary Walls)X = Center to Center Spacing of Tiebacks(ft)Equation 6: Simple Retaining Wall Load It is highly recommended to consult a registeredP HM= 24 x (H + S) 2(Moist - No Water Pressure) professionalengineerwhenmorecomplexEquation 7: Simple Retaining Wall Load surcharge loads such as a structure, parking lot,P HS= 50 x (H + S) (Saturated - Water is Present) road, etc. is located on the surface near the top of2 the retaining wall.Where: Horizontal Embedment LengthL 0 : TheP HS= Saturated Soil Load on Wall - (lb/lineal foot) TorqueAnchormustbeinstalledintosoilaP HM= Moist Soil Load on Wall - (lb/lineal foot)H = Height of Backfill - (ft) sufficient distance away from the wall so that theS = Height of Soil Surcharge - (ft) helicalplate(s)canfullydevelopanchoringSimpleRetainingWallTieback Applications beyond any failure planes. (See Figure 3.)with Soil Surcharge: A load on a retaining wall Equation 9: Horizontal Embedmentwith a simple soil surcharge load such as shown L 0= H + 10d largestinFigure6mayalsobeapproximatedusingEquations6&7.Onemustfirstestimatethe Where:surcharge height, S as shown. L 0= Minimum Horizontal Embedment Lengthfrom Wall to the Shallowest Plate(ft)Whenwaterpressureis presentbehindthe H=Height of Soil Against Wall - (ft)retainingwallor itisunknownifhydrostatic d largest= Diameter Of Largest Plate - (ft)pressureexists, Equation7mustbeusedto Installation Angle: Typically in tiebackestimate the load on the retaining wall. applications,TorqueAnchorsareinstalledatUltimateTiebackCapacitySelection: To downwardanglesof5 0 to30 0 measuredfromhorizontal. Mostoftenthedesignercallsfordeterminetheultimatetiebackcapacity installed angles between 10 0and 20 0 .The largerrequirement, multiply the soil force against the the angle, the less shaft material is required towallbytheselectedcentertocentertieback reach theCriticalEmbedmentDepth - D cr .spacingappropriatefortheexistingorplanned One also must be aware that the shaft must alsowall construction and loading.H/2SOIL SURCHARGE "S"T U T UTIEBACK TIEBACKPLACEMENT PLACEMENT0.25H TO 0.45H 0.2H TO 0.4HWALL WALLP H HEIGHT P H HEIGHT(EQUATIONS"H" (EQUATIONS"H"7 OR 8) 7 OR 8)Figure 5. Simple Retaining Wall Tieback Application Figure 6. Simple Retaining Wall with Soil SurchargeECP Helical Torque Anchors Technical Service Manual2021 Earth Contact Products, L.L.C.2021-09 Chapter 1 - Page 31 All rights reserve'