DESIGN OF RETAINING WALL ( THAPAR, DERABASSI ) Design Data 1 Height of Earth to be Retained 2 Angle of Repose, φ
1.65 30 0.52 0.45
3 Coeff. Of Friction b/w Soil & Concrete, µ
2
170 kN/m 3 18 kN/m 0.90 m 0.075 m 0 DEGREE 0.33 3.0 2.48 m
4 Gross Safe Bearing Capacityof Soil 5 Unit Weight of soil, γs 6 Depth of Foundation 7 P.C.C Below Footing 8 Surcharge Angle,θ 9 Earth Pressure Coeff., Active 10 Earth Pressure Coeff., Passive 11 Total Height of Retaining Wall Material Used Concrete Grade Steel Grade
M 25 Fe 500 3 25 kN/m
Unit Weight of R.C.C Section of Retaining Wall Thickness of Base Slab Length of Base Slab, B Length of Heel Slab Stem Thickness
0.275 1.5 1.27 0.23
Height of Wall Above Base Slab, h
1 2 3 4
Designation Force,KN Weight of Soil above Heal (W1) Weight of Stem (W2) Weight of Base Slab (W3) Pa
m m m m
2.20 m
Stability Checks S.No
UNITS m DEGREE RADIANS REF. TABLE 1
Table-2
50.292 12.650 10.313 18.377
Dis. from Heel,m Moment,KNm 0.64 31.94 1.39 17.52 0.75 7.73 0.83 15.16
Table-1 Soil Coarse Grained (no silt)
µ 0.55
Coarse Grained (silt)
0.45
Silt
0.35
Sound Rock
0.6
Total (W) 73.25 * Note Passive Earth Pressure Not Consireded.
72.351
0.99 m Dis. Of Point of Application of Resultant Force from Heel end, Z Eccentricity e=Z-B/2 0.24 < B/6 = 0.250 Eccentricity less then B/6, so there is no uplifting, Hence Safe Extreme Earth Pressure at the Base, W/B(1±6e/B) Minimum Pressure Maximum Pressure Maximum Pressure less than SBC hence safe
2 2.41 kN/m 2 95.26 kN/m
Check for Overturn Resisting Moment about Toe, Mr Overturning Moment about Toe, Mo Factor of Safety against Overturning, 0.9*Mr/Mo Factor of Safety greater than 1.4 hence safe
37.53 KNm 15.161 KNm 2.227945
Check for Sliding Resisting Force Due to Overlying Weight, µW Sliding Force, Pa (Active Pressure Force) Coefficient of Sliding Friction, Fs Factor of Safety greater then 1.4 hence safe
32.96453 KN 18.38 KN 1.61 KN
Design of Vertical Stem Height of Cantilever above Base, h B.M at Base Bending Moment (Factored), Mu Clear Cover Effective Depth, deff 1
Calculation of Steel Mu/bd2
(FROM SP-16 ) 2
Ast Required Diameter of Bar
169.2 mm /m 10 mm
Area of Bar Required Spacing of Provide
2 78.54 mm 464 mm 300 mm
10
10 Dia Bars mm Dia Bars @
8
C/C C/C
2 276 mm /m 8 mm
Required Distribution Steel: Diameter of Bar Area of Bar Required Spacing of Provide
4
60.615 mm
0.391 0.094%
Required Percentage of Steel
3
m KNm/m KNm/m mm mm
Chech for Depth Depth Required from B.M Depth Required is less than Depth Provided hence OK
2
2.200 8.451 12.676 50 180
8 Dia Bars mm Dia Bars @
2 50.27 mm 182 mm 250 mm
C/C C/C near each face
Calculation of Steel at Outer Face Provide min. % of Steel at Outer Face Required Percentage of Steel
2 216 mm /m 10 mm
Ast Required Diameter of Bar Area of Bar Required Spacing of Provide
0.12%
10
10 Dia Bars mm Dia Bars @
2 78.54 mm 364 mm 300 mm
C/C C/C
Design of Base Slab 2 95.263245 kN/m
Pressure at outer face of Stem
2 81.03 kN/m
Pressure at the junction of Heel and Stem B.M Calculations per meter width: Crictical Section : Stem Heel junction Load Due to
Magnitude, N
Upward Pressure Positive iii) Positive iv) Downward Weight Negative DL Heel Slab Soil Net Moment
Distance from c, m
3.060 49.92
0.635 0.42
1.94 21.13
-8.731 -50.292
0.635 0.635
-5.54 -31.94 -14.40
Net Moment Bending Moment (Factored), Mu Clear Cover Effective Depth, deff
14.40 21.60 0.05 0.225
2
Mu/bd
Required Percentage of Steel, p Ast Required Diameter of Bar Required Spacing of Provide
Area of Bar 10 Dia Bars 10 Dia Bars @
DISTRIBUTION STEEL: Diameter of Bar Required Spacing of Provide
Moment About c, KNm
Area of Bar 10 Dia Bars 10 Dia Bars @
KNm KNm m m
HOGGING
0.427 0.11% 2 252 mm 10 mm 2 78.54 mm 311.7 mm 150 mm
C/C C/C
2 330 mm /m 10 mm 2 78.54 mm 238.00 mm 200 mm
C/C C/C
(AT BOT.)
PROVISION OF PILES UNDER RETAINING BASE Site Condition at the Location of Boundary Wall is such that the Adjoining Land is lowlying and Regular Erosion of Soil Takes place specifically during rains. In an earlier event the same retaining wall had fallen as the soil below the retaining foundation had eroded thereby leading to overturning of the wall. So it is proposed to provided piles under the base so that in an event of erosion of soil under the footing shall not render the retaining unsafe and leading to failure Design Basis for selection of pile configuration Minimum Pressure under Base =
2.41 kN/m2
Maximum Pressure under Base =
95.26 kN/m2
Average Pressure under Base =
49 kN/m2
Width of Base Footing
1.5 m
Force / Metre under Retaining Wall
73.2545 kN/m
Adopt a Pile Footing of Dia 300 mm ( Single Underreamed) and length of 4 m Capacity of Pile ( Table 1 : IS 2911, Part 3 ) ( Compression )
18.3 Ton
Capacity of Pile ( Table 1 : IS 2911, Part 3 ) ( Uplift )
9.75 Ton
Pile Arrangement suggested is Alternate Pile Under Stem and Heel so as to achieve minimum pile distance of 3 times the dia for fully effective pile capacity in group within given footing width Since Settlement under Stem Side can lead to Uplifting on Heel Side, Average Pile Value of Compession and Uplift has been used for Design to be on Conservative Side Average Capacity of Pile
14.025 Ton
Required Spacing of Pile
1.91 m
Provide Piles at a spacing of 1.625 m alternatively on Heel & Stem Side
Regular ad fallen
e footing
