cable trench is 456

Sec 1-1DESIGN OF CABLE TRENCH SECTION 1-1For detail of sectionTB 0 332 316 004Design of cable trench wallMin depth of trench wall below ground level1.625mAssuming max. length of trench as 55m with longitudinal slope of 1 : 750 (length upto section 1-1&4-4)Depth of trench wall due to slope55/750=0.073mMax depth of trench Wall(from GL)1.625+0.0731.698m (MAX.)Max. Total Height of cable Trench wall1.823Surcharge pressureq =2000kg/m2Soil densityg =1800kg/m3Angle of internal frictionf =0oCoefficient of internal frictionKa =(1-sin0)/(1+sin0)=1.000Weight of tray+cable +connector(w1)(refer email dated 26.06.13)80kg/m lengthof wallWidth of tray0.75mNo. of trays5CASE-I : When no water in the trench and soil outside the wallLateral stress over the wall due to uniform surcharge pressure( Ka x q)=2000.00kg/m2Total active thrust due to surcharge(P1)2000.00x1.70=3396.67kg/mActive thrust due to Backfill (P2=1/2*Ka*g*H^2)0.5*1800*1*1.698^2=2595.90kg/mTotal active thrust (Pa)3396.67+2595.90=5992.6kg/mPa acts at a distance 'y' above A and acts horizontally. Taking moment about A5992.57*y=3396.67*1.698/2+2595.9*1.698/3y =0.727mBending moment at the base of wall5992.6x0.727=4353.91kg-m/m( Considering 1m length of wall)Moment from tray (Connected from wall)80x (0.75)/2x5150.00kg-mTotal moment4353.91+150.0=4503.91kg-mDesign moment, Mu11.50x4503.91=6755.86kg-mConcrete gradeM25CASE-II : When water in the trench and no soil outside the wallDepth of water1.698=1.698mActive thrust due to water0.5 x1000 x1.698^2 =1442.168kg/mBending moment at the base of wall1442.1680555556x1.698/3 =816.43kg-m/m( Considering 1m length of wall)Design moment, Mu21.50x816.43=1224.64kg-m250GLBGLP116981.698P2750yH/3H/2ADesign moment for wall6755.9kg-mRequired thickness of wall(6755.86* 104 / 0.138*25*1000)^0.5139.94mmd = (Mu / .138x fck x b)0.5Providing, D400mmEffective depth, d400-40-5 =355mmReinforcementMu/bd2 =6755.86x 104 /1000 x3552 =0.54Required % of steel, Pt=0.152(Refer SP16,tab;Table 1)Required area of steel(0.152x 1000 x355)/100 =540.84mm2Providing main reinforcement12f @140C/CArea of steel provided=807.4mm2Minimum reinforcement = 0.12% (As per IS 456)=480.0mm2Providing distribution reinforcement10f @200 C/C1199.9Area of distribution steel provided=392.5mm2Design of BracketAsuuming live load at the end of bracket=80kgMoment due to w1( wt. of cable+tray)80*0.75*0.75/2+80*0.7582.50kg-m8250.00kg-cm'Z' required8250.00/2500=3.30cm3Providing L50x50x6 bracketsZprovided =3.6cm3Check for Uplift(for max. depth)Pressure due to trench (Only Dead Loads) =2489.37kg/m2/m(0.9 times the vertical load)Uplift pressure due to water =2198.33kg/m2/m2198.3333333333F.O.S. for Uplift =1.132