b'Design Example 4Retaining Wall Tieback Anchor Cohesionless SoilStructural Details: A H= 0.328 + 0.524 + 0.764 = 1.62 ft 2 Newconstructionsteelreinforcedcastconcrete q =x h midretaining wall12 ft tall h = Design Embedment = 10 ft. is selected Backfilled with granular fill at the wall with free (This is the measurement from the groundflow drainage tiles at the footing surface to where the 12 diameter helical Thesoilinformationaboutthesiteindicated plate is located when the tieback is fullymediumtocoarsegravellysand(SP),Medium installed - See Figure 10, below.)dense130 pcf = Soil density = 130 lb/ft 3 Standard Penetration Blow count N = 20 blows N q =23(N=20& =33 0 )Table7 -per foot at 10 feet deep= 32 0 Chapter 11.Estimatethelateralsoilforceagainstthe T u= 1.62 ft 2x (130 lb/ft 3x 10 ft) x (23)wall. Equation6 fromChapter1isselected T u= 48,438 lbbecause the design specifies that the hydrostatic 3. TorqueAnchorSpacing. Determinethepressure is relieved by the drainage system. Torque Anchor spacing along the wall for theP H= 24 x (H 2 ), Where, H = 12 ft. configurationselected.UseEquation4fromP H = 24 x (12 x 12) = 3,456 (Use 3,500) Chapter 1.P H = 3,500 lb/lineal foot X = T u/ [P H x (FS)], Where,X = Product Spacing2. Select a Torque Anchor and perform an T u = Ultimate Capacity on Torque Anchor analysis to see if it is suitable.In this example P H = Lateral Force on Wall (lb/lin.ft)theTAF-175-6008-10-12istried, thisis a1- FS= Factor of Safety (Typically 2.0:1)3/4 solid square bar product with an 8, 10 and X = 48,438 lb/[3,500 lb/lin.ft x 2 (FS)] = 6.9a12diameterhelical plateattached. The 4. Installation Torque & Embedment. Useavailablesoil reportsthesoiliscohesionless; Equation3 fromChapter1tocalculatetheEquation 1b from Chapter 1 is used: installation torque required for this anchor.T u = A H(q N q ) Where, T = T u/ k Where,A H= A 8 + A 10 + A 12 T u= 48,438 lb (Step 3)A 8 = 0.328 ft 2(Ref. Table 10 in Example 3k = 10 (Table 12Chapter 1 or Example 3)A 10 = 0.524 ft 2 also Table 10Chapter 1) T = 48,438 lb/10 ft -1= 4,844 ft-lb.A 12 = 0.764 ft 2 T = 4,900 ft-lbNO SOIL SURCHARGEGRAVELLY ECP TAF-175-60 (8,10,12) T = 48,318 lbSAND, MEDIUM DESIGN TORQUE ANCHOR U SOILSPT, "N" = 10 EMBEDMENT HEIGHT pcf DEPTH = INSTALLATION TIEBACK 12\'-0" DEG. 10 ft ANGLE PLACEMENT12" 3-1/2\' FROMDIA. TOP OF WALL &10" DIA. HORIZONTALLYP = 3,456 lb/ft AT 7\' O.C.8" DIA. H = 15 deg.PROPERDRAINAGEREQUIRED MIN.HELICAL PLATE L = MIN. HORIZONTALEMBEDMENT EMBEDMENT =LENGTH AT H + (10 x 12" Dia) = 22 ft4,900 ft-lb (Equation 9)= 3 X 12" = 3 ft. EEMB25 ft NTEDMEDQUIR GTH =RE LEN EDTH EQ ) UIR 9.5 ft R= 2 Designed andDU LEN G (3 x 10"CT") +PRO+ (3 x 8 EngineeredL=25 ft To PerformFigure 10.Design Example 4.ECP Technical Design ManualTorque Anchor Design Examples2021 Earth Contact Products, L.L.C.2021-09 Chapter 5Page 94 All rights reserved'