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Home My WebLink About12' calcCDP Wall Civil Design Professionals version 3.1.12265 Project: Candy Cove Location: Prior Lake, MN Designer: BTD Date: 9/26/2012 Section: 12' Design Method: NCMA_09_3rd_Ed Design Unit: ReCon SOIL PARAMETERS φ coh γ Reinforced Soil: 32 deg 0 psf 120 pcf Retained Soil: 32 deg 0 psf 120 pcf Foundation Soil: 32 deg 0 psf 120 pcf Leveling Pad: Crushed Stone GEOMETRY Design Height: 12.00 ft Live Load: 50 psf Wall Batter/Tilt: 3.60/ 0.00 deg Live Load Offset: 0.00 ft Embedment: 1.50 ft Live Load Width: 50 ft Leveling Pad Depth: 1.00 ft Dead Load: 0 psf Slope Angle: 0 deg Dead Load Offset: 0 ft Slope Length: 0 ft Dead Load Width: 0 ft Slope Toe Offset: 0 ft Base Friction: True FACTORS OF SAFETY Sliding: 1.50 Pullout: 1.50 Overturning: 2.00 Uncertainties: 1.50 Bearing: 2.00 Connection: 1.50 Shear: 1.50 Bending: 1.50 RESULTS FoS Sliding: 4.18 FoS Overturning: 7.21 Bearing 1762 FoS Bearing: 10.16 Total Pullout 29953 FoS Total Pullout 12.95 ID Height Length Geogrid.Ta TPa TPqll TPqdl TMax FS_str Tal_cn FS PkConn FS PO / [Tmax]FS slr [fndn] 5 6.67 8.00 5XT 1639 515 72 0 586 4.19 706 1.81 2.07/[586]21.49 4 5.33 8.00 5XT 1639 254 16 0 270 9.10 802 4.45 8.04/[270]15.11 3 4.00 8.00 5XT 1639 305 16 0 321 7.66 897 4.19 10.57/[321]11.37 2 2.67 8.00 5XT 1639 356 16 0 372 6.61 993 4.00 13.12/[372]8.98 1 1.33 8.00 5XT 1639 407 16 0 423 5.82 1088 3.86 15.68/[423]7.34 [4.18] Civil Design Professionals Page 1 COMPOUND RESULTS Compound stability is a global analysis (Bishop) with the failure planes originating at the top of the slope / wall and existing out through the face of the wall. The resistance of the geogrid reinforcement is included in the analysis and the shear resistance of the face units is included. ID Enter Point X Enter Point Y Exit Point X Exit Point Y Center X Center Y Radius FoS 500 22.79 12.00 2.08 1.33 5.59 19.96 18.95 5.379 369 20.39 12.00 2.08 1.33 5.18 17.06 16.02 5.398 654 25.19 12.00 2.08 1.33 5.99 23.22 22.24 5.635 501 22.79 12.00 2.08 1.33 6.57 18.06 17.32 5.667 831 27.59 12.00 2.08 1.33 6.39 26.85 25.88 5.691 370 20.39 12.00 2.08 1.33 6.09 15.49 14.72 5.716 259 17.99 12.00 2.08 1.33 5.62 13.26 12.44 5.747 830 27.59 12.00 2.08 1.33 4.98 30.23 29.04 5.794 655 25.19 12.00 2.08 1.33 7.04 20.95 20.24 5.883 832 27.59 12.00 2.08 1.33 7.51 24.17 23.48 5.923 GLOBAL RESULTS Global stability is a global analysis (Bishop) with the failure planes originating at the top of the slope / wall and existing out below the wall in the area infront of the structure. The resistance of the geogrid reinforcement is included in the analysis. The curve may go through the base of the wall and the wall shear would be included. In most cases the failure plane will pass below the structure. ID Enter Point X Enter Point Y Exit Point X Exit Point Y Center X Center Y Radius FoS 139 13.19 12.00 -10.11 1.50 -1.01 12.40 14.20 1.753 247 15.59 12.00 -12.51 1.50 -1.98 16.17 18.05 1.766 236 15.59 12.00 -10.11 1.50 -0.70 15.16 16.59 1.769 260 15.59 12.00 -14.91 1.50 -3.26 17.19 19.55 1.797 370 17.99 12.00 -12.51 1.50 -1.68 19.59 21.08 1.809 386 17.99 12.00 -14.91 1.50 -2.91 20.69 22.63 1.830 402 17.99 12.00 -17.31 1.50 -4.56 23.22 25.18 1.843 149 13.19 12.00 -12.51 1.50 -2.00 12.49 15.20 1.848 259 15.59 12.00 -14.91 1.50 -3.65 18.33 20.25 1.852 248 15.59 12.00 -12.51 1.50 -1.60 15.16 17.48 1.853 Civil Design Professionals Page 2 DESIGN DATA TARGET DESIGN VALUES (Factors of Safety) Minimum Factor of Safety for the sliding along the base FSsl = 1.5 Minimum Factor of Safety for overturning about the toe FSot = 2.0 Minimum Factor of Safety for bearing (foundation shear failure) FSbr = 2.0 -Seismic requirements are 75% of MINIMUM DESIGN REQUIREMENTS Minimum embedment depth Min_emb = 1.5 ft INPUT DATA Geometry Wall Geometry Design Height (top of leveling pad to finished grade at top of wall) H =12.00 ft Embedment (measured from top of leveling pad to finished grade at toe) emb =1.50 ft Leveling Pad Depth LP =1.00 ft Face Batter (measured from vertical) i =3.6 deg Slope Geometry Slope Angle (back slope angle measured from horizontal)β =0.0 deg Slope toe offset (horiz. bench from wall to toe of slope) STL_offset =0.0 ft Slope Length (horiz. length from wall to top of slope) SL_Length =0.0 ft NOTE: If the slope toe is offset or the slope breaks within three times the wall height, a Coulomb Trial Wedge method of analysis is used. Surcharge Loading Live Load (assumed transient loading (e.g. traffic)) LL = 50 psf Live Load Offset (measured from back face of wall) LL_offset = 0.0 ft Live Load Width (assumed strip loading) LL_width = 50.0 ft Soil Parameters Reinforced Zone Angle of Internal Friction φ = 32 deg Cohesion coh = 0.0 psf Moist Unit Weight gamma = 120 pcf Retained Zone Angle of Internal Friction φ = 32 deg Cohesion coh = 0.0 psf Moist Unit Weight gamma = 120 pcf Foundation Angle of Internal Friction φ = 32 deg Cohesion coh = 0.0 psf Moist Unit Weight gamma = 120 pcf Civil Design Professionals Page 3 RETAINING WALL UNITS STRUCTURAL PROPERTIES: N is the normal force [or factored normal load] on the base unit The default leveling pad to base unit shear is 0.8 tan(φ) [AASHTO 10.6.3.4] or may be the manufacturer supplied data. φ is assumed to be 40 degrees for a stone leveling pad. Unit Designation: A-24 Unit Dimensions: Height = 1.33 ft Depth = 2.00 ft Width = 4.00 ft Density = 147.50 pcf Weight = 1573.33 lbs Unit to Unit Shear Unit to Leveling Pad Shear τ = N tan(10.00) + 6775.00 ppf τ = N tan(33.40) + 0.00 ppf Civil Design Professionals Page 4 GEOGRID REINFORCING STRUCTURAL PROPERTIES: Mirafi GEOGRID PROPERTIES Name Tult RFcr RFd RFid Ci Cd Alpha LTDS 2XT 2000 1.58 1.1 1.1 0.8 0.8 0.8 1046 3XT 3500 1.58 1.1 1.1 0.8 0.8 0.8 1831 5XT 4700 1.58 1.1 1.1 0.8 0.8 0.8 2458 7XT 5900 1.58 1.1 1.1 0.8 0.8 0.8 3086 8XT 7400 1.58 1.1 1.1 0.8 0.8 0.8 3871 18XT 9360 1.58 1.1 1.1 0.8 0.8 0.8 4896 10XT 9500 1.58 1.1 1.1 0.8 0.8 0.8 4969 20XT 10705 1.58 1.1 1.1 0.8 0.8 0.8 5599 CONNECTION STRENGTHS Geogrid Slope 1 Intercept 1 Peak Break Slope 2 Intercept 2 Max Normal Rup Conn Conn Creep 5XT 20.00 487 3582 3.00 1603 5992 False 1.00 8XT 21.00 508 -1 0.00 0 5992 False 1.00 10XT 24.00 1370 -1 0.00 0 5999 False 1.00 SHEAR STRENGTHS ID Shear_Slope Shear_Intercept Civil Design Professionals Page 5 CALCULATION RESULTS OVERVIEW CDP Wall calculates stability assuming the wall is a rigid body. Forces and moments are calculated about the base and the front toe of the wall. The base block width or bottom reinforcement length is used in the calculations. The concrete units, granular fill over the blocks or reinforced zone soils are used as resisting forces. EARTH PRESSURES The method of analysis uses the Coulomb Earth Pressure equation (below) to calculate active earth pressures. Wall friction is assumed to act at the back of the wall face. The component of earth pressure is assumed to act perpendicular to the boundary surface. The effective delta angle is delta minus the wall batter at the back face (assumed to be vertical). If the slope breaks within the failure zone, a trial wedge method of analysis is used. INTERNAL EARTH PRESSURES Effective internal Delta angle (2/3 phi) delta =21.3 deg Coefficient of active earth pressure ka =0.250 Internal failure plane ρ = 55.8 deg EXTERNAL EARTH PRESSURES Effective external Delta angle delta =32.00 deg Coefficient of active earth pressure ka =0.250 External failure plane ρ = 54.4 deg FORCES AND MOMENTS CDP Wall resolves all the geometry into simple geometric shapes to make checking easier. All x and y coordinates are referenced to a zero point at the front toe. The wall image can be exported to CAD for a more detailed output. Name Factor γ Force (V)Force (H)X-len Y-len Mo Mr Face Blocks(W1)1.00 3540 --1.33 ----4695 Soil(W2)1.00 423 --2.39 ----1011 Soil(W3)1.00 7794 --5.29 ----41261 Soil(W4)1.00 544 --8.25 ----4485 LL(W7)1.00 308 --5.67 ----1749 Pa_h 1.00 --1902 --4.00 7607 -- Pa_v 1.00 1028 --8.25 ----8485 Pq_h 1.00 --132 --6.00 792 -- Pq_v 1.00 71 --8.38 ----598 Sum (V, H)1.00 0 2034 Sum Mom 8399 60535 Note: live load forces and moments are not included in SumV or Mr as live loads are not included as resisting forces. Civil Design Professionals Page 6 BASE SLIDING Sliding at the base is checked at the soil-to-soil interface between the reinforced mass and the foundation soil. Forces resisting sliding = (SumV) SumV=13709 ppf Resisting force = SumV x tan(slope) + c x L Rf1 =8496 where L is the base width Driving force is the horizontal component of Pah + Pqh+ Pdh Df = 2034 Factor of Safety = Rf/Df FSsl =4.18 Friction angle is the lesser of the leveling pad and Fnd φ = 32.00 deg Driving force is the horizontal component of Pah + Pqh Df =2034 Factor of Safety = Rf/Df FSsl =4.18 OK Civil Design Professionals Page 7 OVERTURNING ABOUT THE TOE Overturning at the base is checked by assuming rotation about the front toe by the block mass, soil retained on the blocks or within the reinforced zone. Allowable overturning can be defined by eccentricity (e/L) or by the ratio of resisting moments divided by overturning moment (FSot). Moments resisting overturning = Sum(M1 to M6) + MPav + MPqv Mr =60535 ft-lbs Moments causing overturning = MPah + MPqh Mo =8399 ft-lbs Factor of safety = Mr/Mo FSot =7.21 OK Civil Design Professionals Page 8 TENSION CALCULATIONS Tmax is the maximum tension in the reinforcing based on the earth pressure and surcharge loads applied. In the NCMA design method, earth pressures are calculated using the Coulomb Earth pressure equation. Infinite surcharge loads are applied as q x ka. In designs were there is a broken back slope, or the surcharge is not uniform over the area, a tie-back wedge analysis method is used. TABLE OF RESULTS Elevation[ ft]Name[ ft]Ta[ ppf]Coverage Ratio %Tmax[ ppf]FS Str 6.67 5XT 1639 100 586 4.19 5.33 5XT 1639 100 270 9.10 4.00 5XT 1639 100 321 7.66 2.67 5XT 1639 100 372 6.61 1.33 5XT 1639 100 423 5.82 Civil Design Professionals Page 9 PULLOUT CALCULATIONS Pullout is the amount of resistance of the reinforcing has to a pullout failure based on the Tmax applied and the depth of embedement (resistance). In an NCMA design the failure place is defined as the Coulomb failure plane which varies with face batter, backslope angle, and surcharge loads applied. All failure planes begin at the tail. of the facing units. For AASHTO calculations, the liveload surcharge is not included in the Tmax value for pullout. Failure Plane Angle = 55.8 Deg NOTE: The pullout capacity is limited by the LTDS of the reinforcing layer, not the ultimate pullout capacity calculated. F* = Ci x tan(phi) = 0.80 x 0.62 = 0.50 Pullout = 2 x Le x F* x sv x alpha x Coverage TABLE OF RESULTSPeak Connection = N tan(slope) + intercept Connection Capacity = [N tan(slope) + intercept] / RFcr /tRFcr can be a value obtained from long-term testing or by default could be the creep reduction factor of the geogrid reinforcing. TABLE OF RESULTS Elevation[ ft]Ci % Coverage Tmax[ ppf]Le[ ft]La[ ft]Pullout_[Pr][ ppf]FS PO 6.67 0.80 100 586 1.89 6.11 1211 2.07 5.33 0.80 100 270 2.71 5.29 2171 8.04 4.00 0.80 100 321 3.54 4.46 3394 10.57 2.67 0.80 100 372 4.36 3.64 4879 13.12 1.33 0.80 100 423 5.18 2.82 6627 15.68 Civil Design Professionals Page 10 CONNECTION CALCULATIONS Connection is the amount of resistance of the reinforcing has to a pullout failure from the facing units based on the Tmax applied and the normal load on the units. In an AASHTO LRFD design, creep on the connection may be applied for frictional and mechanical connections. In NCMA or AASHTO 2002, a frictional failure is based on the peak connection capacity divided by a factor of safety. For a rupture connection the capacity is the peak load divided by a creep reduction factor and a factor of safety. Frictional ConnectionRupture Connection Elevation[ ft]Name Tmax[ ppf]% Coverage N[ ppf]Avail_CN[ ppf]FS cn 6.67 5XT 586 100 1573 706 1.20 5.33 5XT 270 100 1967 802 2.97 4.00 5XT 321 100 2360 897 2.80 2.67 5XT 372 100 2753 993 2.67 1.33 5XT 423 100 3147 1088 2.57 Civil Design Professionals Page 11