Round off your results appropriately in each case. Work without appropriate UNITS will be returned without grading.
Note: Total allowable settlement = 25 mm.
Q1. Fig.1 shows the soil profile and Table below shows the SPT N data. Bore hole size = 100 mm. Standard split spoon sampler and standard energy were applied for SPT tests.
Apply rod-length corrections, and overburden stress correction. Determine (N1)60, estimate relative density Dr, friction angle Φ', and modulus E and plot all of them in a figure. Depth must be plotted increasing downward in the figure. Appropriate scale must be used for axes.
Q2. Determine the allowable bearing stress qall based on both, tolerable settlement and ultimate bearing capacity qult with at least FS=3, for the following cases (a) to (c).
Use (a) Terzaghi & Peck method, as well as (b) Schmertmann's method (use simplified Iz diagram) for settlement calculations. Ignore creep settlement.
a) Strip Footing, B= 1.75m, Depth of embedment = 1m.
b) Rectangular Footing: B=1.75m, L=2B, Depth of embedment = 1m.
c) Circular Footing (same cross sectional area as (b)). Depth of embedment = 1m.
d) Determine the allowable Load Q for a, b, and c. Depth of embedment = 1m. Neatly tabulate your results.
Fig.1: Soil Profile at a Site
Sand
Assume moist unit weight = 16.4 kN/m3
Ground water (1m below ground level), Assume saturated unit weight = 18.5 kN/m3;
Unit weight of water = 9.81 kN/m3
Bedrock at 15m depth
|
Depth
|
SPT
|
|
m
|
Nm
|
|
0
|
|
|
1
|
10
|
|
2
|
12
|
|
3
|
16
|
|
4
|
8
|
|
5
|
10
|
|
6
|
12
|
|
7
|
15
|
|
8
|
13
|
|
9
|
16
|
|
10
|
20
|