According to IS code method, what is the formula of reduction factor during effect of water table on bearing capacity of soil. (where, R_W = reduction factor)

Question

Question

This question was previously asked in

HPCL Engineer Civil 23 Dec 2023 Official Paper

\( \mathrm{R}_{\mathrm{w}}=0.5\left(1+\frac{\mathrm{Z}_{\mathrm{w} 2}}{B}\right) \\\)
\( \mathrm{R}_{\mathrm{w}}=0.5\left(1+\frac{\mathrm{Z}_{\mathrm{w} 2}}{\mathrm{D}}\right) \\\)
\( \mathrm{R}_{\mathrm{w}}=0.5\left(1-\frac{\mathrm{Z}_{\mathrm{w} 2}}{B}\right) \\\)
\( \mathrm{R}_{\mathrm{w}}=0.5\left(\frac{\mathrm{Z}_{\mathrm{w} 2}}{\mathrm{D}}\right) \)

Answer 1

1Concept:

Rw1 & Rw2 = Water table correction factors

Rw1 = 0.5 (1 + Dw1 /Df) when 0 < Dw1 /Df <1

Rw2 = 0.5 (1 + Dw2 /B) when 0 < Dw2 /B <1

where Dw1 = Depth of water table between ground level and base of the footing

Dw2 = Depth of water table below the base of the footing

From above we can maximum value of the water table correction factor can be 1, when either Dw1 = Df or Dw2 = B

Putting these values in the formula above, we get

Rw2 = \( \mathrm{R}_{\mathrm{w}}=0.5\left(1+\frac{\mathrm{Z}_{\mathrm{w} 2}}{B}\right) \\\)

Additional Information

Rw1 = 0.5 (1 + Dw1 /Df)

D_w1 = 0

R_w1 = 0.5 × 1 = 0.5

Download Solution PDF