Formation level = m. Foundation level = m. Height of the wall above the Ground Level = 7.42 m

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Kelly Fox
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1 DESIGN OF RETAINING WALL INTRODUCTION: This wall is designed for active earth pressure and live load surcharge pressure The loads for the purpose of design are calculated per meter length of wall. BASIC DESIGN: Formation level = m Foundation level = m Height of the wall above the Ground Level = 7.42 m Depth of foundation below Ground level = 1.50 m Slope of surcharge is = 0.00 degree Safe bearing capacity = kn/m 2 MATERIALS: Grade of concrete = M 25 Permissible flexural compressive stress σcbc = N/mm 2 modular ratio m = = 10 for roads, means of IS [ 280/3σcbc ] Neutral axis depth factor n = (1/(1+(200/(10*8.333))) = Leverarm factor j = ( /3) = Moment resistance factor Q = (0.5*0.294*0.902*8.333) = N/mm 2 Maximum shear stress = 1.90 N/mm 2 from code Clear cover to the reinforcement = 50 mm Clear cover to footing reinforcement = 75 mm Density of concrete = 24 kn/mm 3 Development length factor Ld = 46 Ø Grade of steel = Fe 415 Tension in flexure, shear or combined bending σ st = 200 N/mm 2 Back Fill : Angle of slope of the embankment or backfill β = 0 degree Angle of internal friction φ = 30 degree Angle of internal friction soil to soil δ = 20 degree Inclination of wall with respect to vertical α = 7 degree

2 Cohesion c = kn/m 2 Density of earth γ = kn/m 3 Density of water γ W = kn/m 3 Coefficient of active earth pressure in horizontal direction LOADS : Ka = = cos 2 α [1+ ( sin (φ + δ) cos (φ β))] 2 ( cos (α + δ) cos (α β)) Active earth pressure at bottom of footing level = K a γ h = kn/m 2 Due to live load surcharge = (0.307*18*1.2) = kn/m 2 Depth of potensial tension crack due to cohesion "z" = m - 2c/(γ(K a )0.5) Live load surcharge = 1.20 m of back fill cos 2 (φ α) Active Earth Pressure Liveload Surcharge 7.42 a B A GL C 1.50 F E b e c f d D Toe slab Heel slab

3 DESIGN OF STEM: Top straight portion of the stem Dry condition: Force due to active earth pressure = (0.5*15.209*2.75) = kn Lever arm = (0.42*2.75) = m Bending moment = (20.912*1.155) = kn.m Force due to surcharge = (6.637*2.75) = kn Lever arm = (2.750*0.5) = m Bending moment = (18.251*1.375 = kn.m Total Design BM = ( ) = kn.m Design BM = kn.m d, Required = (SQRT((49.249* /(1.105*1000))) = mm d, Provided = (0.3*1000) = mm SAFE Ast Required = (49.249* /(200*0.902*226)) = mm 2 Minimum steel required is = 0.12% = mm 2 Providing tor 125 mm Steel provided = mm 2 SAFE Base of the stem: Dry condition: Force due to active earth pressure = 0.5*42.696*7.72 = kn Lever arm = (0.42*7.72) = m Bending moment = ( *3.242) = kn.m Force due to surcharge = (6.637*7.720) = kn Lever arm = (7.720*0.5) = m Bending moment = (51.235*3.860) = kn.m Total Design BM = ( ) = kn.m Design BM = kn.m d, Required = (SQRT(( * /(1.105*1000))) = mm d, Provided = (1.2*1000) = mm SAFE Ast Required = ( * /(200*0.902*1112.5)) = mm 2

4 Minimum steel required is = 0.12% = mm 2 Providing tor 125 mm + tor 125 mm Steel provided = mm 2 SAFE CHECKING BASE PRESSURE : For checking the base pressure all the loads acting on the base slab are calculated about TOE of th base slab. The load calculations are listed in following table. Force and BM due to active earth pressure are considered as -ve for sign convention purpose. S.no. Description Load in KN Load in kn Lever V H arm in BM in kn.m 1 Active earth pressure Liveload surcharge Vertical component due to 3 Active earth pressure Vertical comp. of live load surcharge Earth weight A B C D Wt.of earth on toe E F Self weight of wall a b c d e f Sum of P = kn Net BM = kn.m Sum of H = kn Self weight of wall = kn Eccentricity = e(=b/2 - M/V) = m SAFE Check for base pressure Maximum (P/A + Pe/Z) = kn/m 2 SAFE Minimum (P/A - Pe/Z) = kn/m 2 SAFE

5 CHECK FOR STABILITY Stability against Sliding Total Vertical load = kn Total Horizontal load = kn Tanφ = Factor of safety against sliding = >1.5 SAFE Stability against Overturning Restoring moment RM = kn.m Overturning moment is due to earth pressure OM = kn.m Factor of safety against Overturning (RM / OM) = >2 SAFE DESIGN OF TOE SLAB: BM due to base pressure = kn.m BM due to self weight of slab = kn.m BM due to weight of earth on toe = kn.m Total BM = kn.m Design BM acting on the Toe slab = knm Effective depth requireddreq = mm Providing overall depth as = mm Effective depth provided = mm SAFE Steel required = mm 2 Minimum steel required is 0.12% = mm 2 Providing tor 100 mm C/C = mm 2 SAFE Check for Shear: Critical section at a distance (eff. depth) i.e. = mm from the face of the support: Overall depth provided = m Effective depth = mm Due to base pressure = kn Due to self weight of slab = kn Total shear at c = kn

6 BM due to base pressure = kn.m BM due to self wt. of slab = kn.m BM at c = kn.m Design shear (V±M tanb/d) = kn Shear stress τ = (V±M tanb/d)/bd τ = SAFE 100 As/bd = Permissible Shear stress in concrete with out shear steel = N/mm2 Hence Shear Reinforcement is NOT required. DESIGN OF HEEL SLAB BM due to base pressure = kn.m BM due to self weight of slab = kn.m BM due to weight of earth on Heel = kn.m Total BM = kn.m Design BM acting on the Heel slab = kn.m Effective depth requireddreq = mm Providing overall depth as = mm Effective depth provided = mm SAFE Steel required = mm 2 Minimum steel required is 0.12% = mm 2 Providing tor 125 mm C/C = mm 2 SAFE Check for Shear: The slab is checked for shear at face of the support = kn Tan of Angle between top and bottom edges of the heel slab = Design shear force considering the effect of slope of the slab = kn Shear stress = N/mm As/bd = Permissible Shear stress in concrete with out shear steel = N/mm 2 Hence Shear Reinforcement is NOT required.

DESIGN OF AXIALLY LOADED STEPPED FOOTING DATA :- SBC of soil =200 KN /m 2 Concrete Mix =M20 Steel Grade = Fe 415 Clear cover of bottom slab =50 mm

DESIGN OF AXIALLY LOADED STEPPED FOOTING DATA :- SBC of soil =200 KN /m 2 Concrete Mix =M20 Steel Grade = Fe 415 Clear cover of bottom slab =50 mm STEPPED FOOTING The construction of sloped footing is sometimes difficult and when the slope of the top face of footing is more, say more than 1 vertically to 3 horizontally, it may be difficult to finish