CABLEE Trench Design

DESIGN OF R.C.C.CABLE TRENCH B 1500 x D 1500

1500

150 150

150 1650

1.5 t/m2 (earth)

1500 1 T/m2

Surcharge = Unit wt. of water =

1 T/m

3

Unit wt. of soil =

1.8 T/m

4

25 N/mm2

Grade of concrete

M25

Grade of steel

Fe500

500 N/mm2

1 t/m

Submerged unit wt. of soil gd Coefficient of Earth Pressure =

3

0.5

Depth

150 mm

Effective cover

40 mm

Effective depth

105 mm

Width

1000 mm

DESIGN OF SIDE WALL: 1650

1.65 t/sq.m

UPKIFT

Moment at bottom of wall = Mu/bd2 = pt = Ast (Required) =

1.398 t m/m 1.902 N/mm2 0.484 5.1 cm2

0.750 0.50 t/m2 2 t/m (Surcharge) (water)

PROVIDED

10

DIA. @

150

mm C/C

2

5.23 cm ( pt = 0.498 ) AT BOTTOM.

Check for shear : Shear at the face of support = Nominal shear stress.tv =

2.438 T 0.35 N/mm

tc = 0.85*(0.8fck((1+5b)-1)/6b = where,

b = 0.8 fck/ 6.89pt =

2

0.482 N/mm 5.997

Total pt =

0.484

Shear Capacity=

7.24 T

where,

2

>

2.44 T OK

O.K.

DESIGN OF BASE OF TRENCH

Self weight of trench =

1.69 t/m

Live load over trench =

1 t/m

Total

2.69 t/m

Upward pressure =

1.65 t/m

2

Net pressure =

1.04 t/m

2

Free B.M at span = 2

Mu/bd = pt = Ast (Required) =

PROVIDED

8

0.353 t m/m 0.480 N/mm2 0.120 1.3 cm2

DIA. @

250

mm C/C

2

2.01 cm ( pt = 0.191 ) AT BOTTOM.

O.K.

Distribution Steel:

Distribution reinforcement=

0.060 % of gross cross sectional area on each face

Ast required = 0.06*150*1000/100 Spacing required =

Provide

8

90.00 mm2

558 mm

mm dia

250

mm c/c as distribution reinforcement

OK

10 @ 150 c/c

8 @ 250 c/c 8 @ 250 c/c 1500

8 @ 250 c/c

1500

8 @ 250 c/c

8 @ 250 c/c