Df = 4.00 m

B = 30.00 m

L = 33.00 m

H = 30.00 m

Dw = 10.00 m

w =9.81

KN/m3

SOIL PARAMETERS FOR DESIGN PURPOSES

SOIL PARAMETERS FOR DESIGN PURPOSESSOIL PARAMETERS FOR DESIGN PURPOSES

SOIL PARAMETERS FOR DESIGN PURPOSES

From laboratory test data, the shear strength of CDG are listed below

c (kPa) 3.12 3.65 4.15 4.98 3.56 4.26 3.69

f' (

o

)

38.7 40.8 40.9 41.5 39.5 38.3 36.3

Mat. c (KPa) (degree)

(KN/m3)

Fill

1.50

33.00 19.00

CDG

3.92

39.43 19.00

qu = qc + qq+q

qc= cNcFcsFcdFci qq = qNqFqsFqdFqi q = 1/2BNFsFdFi

qc = 532.53 KPa qq = 6,524.66 KPa q = 20,314.66 KPa

c = 3.92 KPa q = 76.00 KPa = 11.15 KPa

Nc = 70.94 Nq = 59.33 N = 83.92

Fcs = 1.81 Fqs = 1.41 B = 30.00

Fcd = 1.06 Fqd = 1.03 Fs = 1.41

Fci = 1.00 Fqi = 1.00 Fd = 1.03

Fqi = 1.00

qu = 27,371.85 KPa FS = 3.00 qua =

qua =qua =

qua = 9,123.95

9,123.959,123.95

9,123.95

KPa

KPaKPa

KPa

ASSIGNMENT 1 - SHALLOW FOUNDATION HAMZA NADEEM -

ASSIGNMENT 1 - SHALLOW FOUNDATION HAMZA NADEEM - ASSIGNMENT 1 - SHALLOW FOUNDATION HAMZA NADEEM -

ASSIGNMENT 1 - SHALLOW FOUNDATION HAMZA NADEEM -

2010539786

20105397862010539786

2010539786

CIVL6027 Foundation engineering

CIVL6027 Foundation engineering CIVL6027 Foundation engineering

CIVL6027 Foundation engineering

Mean strength parameters

3.92

39.4

Strength

(95% Probability Exceedence

2.92

36.4

(1) Use the Meyerhof method to calculate the ultimate bearing capacity of the raft foundation and the allowable bearing capacity (FS=3).

(1) Use the Meyerhof method to calculate the ultimate bearing capacity of the raft foundation and the allowable bearing capacity (FS=3). (1) Use the Meyerhof method to calculate the ultimate bearing capacity of the raft foundation and the allowable bearing capacity (FS=3).

(1) Use the Meyerhof method to calculate the ultimate bearing capacity of the raft foundation and the allowable bearing capacity (FS=3).

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Mat. c (KPa) (degree)

(KN/m3)

Fill 1.50 33.00 19.00

CDG 2.92 36.43 19.00

qu = qc + qq+q

qc= cNcFcsFcdFci qq = qNqFqsFqdFqi q = 1/2BNFsFdFi

qc = 277.75 KPa qq = 4,221.00 KPa q = 11,186.36 KPa

c = 2.92 KPa q = 76.00 KPa = 11.15 KPa

Nc = 52.68 Nq = 39.88 N = 48.02

Fcs = 1.713 Fqs = 1.357 B = 30.00

Fcd = 1.05 Fqd = 1.03 Fs = 1.357

Fci = 1.00 Fqi = 1.00 Fd = 1.03

Fqi = 1.00

qu = 15,685.11 KPa FS = 3.00 qua =

qua =qua =

qua = 5,228.37

5,228.375,228.37

5,228.37

KPa

KPaKPa

KPa

(2) Using the strength parameters for CDG with 95% probability exceedance, re-calculate the ultimate and allowable bearing capacities of the raft.

(2) Using the strength parameters for CDG with 95% probability exceedance, re-calculate the ultimate and allowable bearing capacities of the raft. (2) Using the strength parameters for CDG with 95% probability exceedance, re-calculate the ultimate and allowable bearing capacities of the raft.

(2) Using the strength parameters for CDG with 95% probability exceedance, re-calculate the ultimate and allowable bearing capacities of the raft.

30

(3) Compare the calculated values in (1) with the presumed allowable bearing pressure in the Code of Practice for Foundations, and state your design considerations

(3) Compare the calculated values in (1) with the presumed allowable bearing pressure in the Code of Practice for Foundations, and state your design considerations (3) Compare the calculated values in (1) with the presumed allowable bearing pressure in the Code of Practice for Foundations, and state your design considerations

(3) Compare the calculated values in (1) with the presumed allowable bearing pressure in the Code of Practice for Foundations, and state your design considerations

(e.g., what value you would take in your design and why; any additional tests you would ask for to support your decision and how).

(e.g., what value you would take in your design and why; any additional tests you would ask for to support your decision and how).(e.g., what value you would take in your design and why; any additional tests you would ask for to support your decision and how).

(e.g., what value you would take in your design and why; any additional tests you would ask for to support your decision and how).

According to the Code of Practice for Foundations (Table 2.1), the allowable bearing capacity of the CDG should be 1000KPa, comparing with the calculated value of 9124 kPa

and 5228 kPa in (1) and (2) respectively . But as we can see this value prescribed in the CoP does not consider variables such as

1. The width of the foundation

2. The depth of the founding level below ground

3. The shape of the foundation

The

calculated value by Meyerhof method will be adopted in our design, as the Meyerhof method calculation considers the geometery of the foundation, which suits the specific

settings of our proposed foundation.

From the calculated values of Bearing Capacity in (1) and (2) it can be seen that the ultimate bearing capacity obtained using the Meyerhof method is sensitive to the soil strength

parameters in particular the friction angle of the soil. Hence it is important to adequtely verify the strength parameters of soil and additional CU tests are recommended to

accurately determine these parameters.

Avg. N value = 100.00

fs = 1.04

zf = 14.69 m

fl = 1.00

ft = 1.00

B = 30.00 m

pa = 100.00 Kpa

qb = 9,123.95

'v = 76.00 Kpa

Ic = 0.0027

w =

w =w =

w = 0.276

0.2760.276

0.276

m

mm

m

(4) Estimate the settlement of the raft foundation under working load.

(4) Estimate the settlement of the raft foundation under working load.(4) Estimate the settlement of the raft foundation under working load.

(4) Estimate the settlement of the raft foundation under working load.

Using the SPT-based method proposed by Burland & Burbidge in 1985, we will calculate the settlement of the foundation.

qu = qc + qq+q Dw = 4.00

qc= cNcFcsFcdFci qq = qNqFqsFqdFqi q = 1/2BNFsFdFi

qc = 532.53 KPa qq = 6,524.66 KPa q = 16,740.65 KPa

c = 3.92 KPa q = 76.00 KPa = 9.19 KPa

Nc = 70.94 Nq = 59.33 N = 83.92

Fcs = 1.81 Fqs = 1.41 B = 30.00

Fcd = 1.06 Fqd = 1.03 Fs = 1.41

Fci = 1.00 Fqi = 1.00 Fd = 1.03

Fi = 1.00

qu =

qu = qu =

qu = 23,797.84

23,797.8423,797.84

23,797.84

KPa

KPaKPa

KPa

(5) Consider a worse scenario that the water table is located at the level of the base of the raft. Recalculate the ultimate bearing

(5) Consider a worse scenario that the water table is located at the level of the base of the raft. Recalculate the ultimate bearing (5) Consider a worse scenario that the water table is located at the level of the base of the raft. Recalculate the ultimate bearing

(5) Consider a worse scenario that the water table is located at the level of the base of the raft. Recalculate the ultimate bearing

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