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C� 5FA Design Group, LLC <br />®� STRUCTURAL I GEOTECHNICAL I SPECIAL INSPECTIONS <br />PROJECT <br />Bankston Residence Underpinning <br />SUBJECT <br />Concrete Backfill Dimensions <br />PROJECT NO. ISHEET NO. <br />CAF <br />Effective Friction Angle = 26' i <br />Passive Coefficient, Kp = tan A2*(45+0'/2) dit": <br />t <br />Ka = 2.57 �nNOH OWE <br />Passive Pressure, Pp = 2.57 * 100 = 257 pcf _ _._ _ _ _, , _ ,. „ ; <br />Cohesion, c' = 1500 psf <br />Soil Unit Weight, y = 100 pcf <br />Depth of Backfill, d = <br />2.0 ft <br />Width of Backfill, w = <br />1.5 ft <br />Depth to Backfill, r= <br />2.0 ft <br />Soil Neglected = <br />1.0 ft <br />Backfill Depth Below Grade = <br />4.0 ft <br />Passive Lateral Resistance Acting on Concrete Backfil)" - `— "- - - -- ---- . <br />Passive Pressure at Base, ap' = Pp*(d+r) <br />256.8pcf * (4 ft) = ap' = 1027 psf <br />Lateral Capacity/Pier, Rp = ((A+B)/2)'d <br />Rp=((A+B)/2)*d=((770 p1f+1541 plf)/2)*2 ft = 2311 Ibs <br />1ftNEGLECTED <br />Depth to Backfill - 1 ft =1 ft <br />Depth of Backfill d = 2 ft <br />Lateral Resistance per Pier - <br />LOADING DIAGRAM PER PIER <br />k = (Kp*y*r)*w = 770 plf <br />Rp = 2311 Ibs <br />I = (Kp*y*(r+d))*w = 1541 plf <br />Isf <br />Concrete Backfill Spacing = 30.0 ft (208) <br />P-Multiplier 1st Backfill = 1.00 Per AASHTO TABLE BELOW <br />P-Multiplier 2nd Backfill = 1.00 (INTERPOLATION OK) <br />P-Multiplier Other Backfiils = N/A <br />Number of Piers to Be Backfilied = 2 pier(s) <br />Lateral Resistance of 1st Backfill = 1 * 2311 Ibs = 2311 Ibs <br />Lateral Resistance of 2nd Backfill = 1 * 2311 Ibs = 2311 Ibs <br />Lateral Resistance of Other Backfilis = N/A <br />Table 10.7.24-1—Pile P-Multipliers, P for Multiple Row Shading (averaged from Hannigan et al, 2006) <br />Pile CTCspachig (in the direcilon of <br />loading) <br />P-Multipliers, P" <br />Row 1 <br />Row 2 <br />Row 3 and Id leer <br />3B <br />0.8 <br />0.4 <br />0.3 <br />SQ <br />1.0 <br />5.85 <br />0.7 <br />- - - ---- --- --- - - -- s -- —----..._- <br />Total Lateral Resistance of Piering System <br />-------------I <br />Lateral Resistance = 1 st Backfill + 2nd Backfill + Other Backfills + Slab + Unpiered + Passive Pressure on Footing + Pier Passive + Tiebacks <br />Total Lateral Resistance = 2311 Ibs + 2311 Ibs + 0 Ibs + 0 Ibs + 0 Ibs + 198 Ibs + 0 Ibs + 0 Ibs = 4820 Ibs <br />Factor of Safety = <br />1.1 <br />Allowable Resistance = <br />4382 Ibs >3879 Ibs OK <br />Polyurethane Foam Capacity --- - _ -- --- - -- ---- <br />_---v— <br />Compressive Strength of Foam = <br />67.0 psi <br />Diameter of Pier = <br />2.875 in 0 <br />Area of Pier Bearing on Foam = <br />69.00 in' <br />Bearing Strength of Pier on Foam = <br />4623 lb <br />Factor of Safety = <br />2.0 <br />Bearing Strength of Pier on Foam = <br />2312 lb OK, Soil Bearing Controls <br />