Question

Q3:- The old building (A) is to be removed and replaced by a new building (B), as shown in Figure (03). The vertical pressure at the center of the clay layer from the building (A) and building (B) is equal to 13.64 kNm and 23.3 kN/m” respectively, Find:- 1. O.C.R after removing building (A). 2. The void ratio (e) of the clay layer: a. Immediately after removing building (A) b. After a very long time from removing building (A). 3. Final consolidation settlement of building (B) if to be constructed: a. Immediately after removing building (A). b. After a very long time from removing building (A). 4. Time required to achieve half the final consolidation settlement of building (B) (14 points) 2 Old building 2 m N.G.L W.TL Sand, y = 15 kN/m Clay, y = 20$ 8 m w -30% G. = 2.7. C.-0.2. C -0.04, C, -0.5m/y Rock Figure (03)
subject / soil mechanics

i want the solution as soon as possible

Answer 1

Solution:

(1) OCR:

Over cosolidation ratio is the ratio of past maximum pressure to the present pressure.

here past maximum pressure was at that time when building A did not remove.

Pressure when building was there = Building pressure + Soil pressure at the middle of clay layer

= 13.64+15*2+20*4

= 123.64 kN/m²

Preseent pressure after removing building A is due to soil only which is equal to 110 kN.

(2) The void ratio of clay layer:

(a) Immediately after removing building A:

$w*G=S_r*e$

$0.30*2.7=1*e$

e = 0.81

(b) After long time from removing building A:

C. e2 ei log(02 - 01)

0.04 e2 0.81 log(123.64 – 110)

$e_2=0.0453+0.81$

$e_2=0.8553$

(3) Final consolidation settlement of Building B if to be constructed:

(a) Immediately after removing building A:

$s_f= (\frac{C_r*H*log(\sigma _c/\sigma_ 0)}{1+e_0}) + (\frac{C_c*H*log((\sigma _c+\Delta \sigma )/\sigma_ 0)}{1+e_0})$

$s_f= (\frac{0.04*10*log(123.64/110)}{1+0.81}) + (\frac{0.2*10*log((110+23.3 )/123.64)}{1+0.81})$

(b) After long time from removing building A:

$s_f= (\frac{C_r*H*log(\sigma _c/\sigma_ 0)}{1+e_0}) + (\frac{C_c*H*log((\sigma _c+\Delta \sigma )/\sigma_ 0)}{1+e_0})$

$s_f= (\frac{0.04*10*log(123.64/110)}{1+0.8553}) + (\frac{0.2*10*log((110+23.3 )/123.64)}{1+0.8553})$

(4) Time required to achieve half consolidation settlement after constructing Building B:

$T_v= \frac{C_v*t}{d^2}$

T_v= time factor... here for 50% consolidation its value is 0.196

d = drainage path = 10m

_Cv = 0.5 ( given in data)

$0.196= \frac{0.5*t}{10^2}$