Reference no: EM132508454

ENEC20003 - Geotechnical Engineering Design Assignment - Central Queensland University, Australia

Assignment Task - Numerical Analysis

1. Definition -

Simulate a consolidation test on a clay layer subjected to both loading and unloading stages using Geostudio Sigma/W package. Assume the following.

Sample diameter: 0.2 m

Sample Height: 1 m

Bulk Unit weight of the sample: 18 kN/m³

Cohesion: 30 kPa

Internal Friction angle: 18^o

Dilation angle: 0^o

Module of Elasticity (E): 2 MPa

Poisson Ratio: 0.334

Permeability in the saturated condition: 1E-7 m/sec

Loading stages:

- Day 0: Insitu analysis- No laoding

- Day 0.01-5: 50 kPa

- Day 5.01-10: 100 kPa

- Day 10.01-15: 200 kPa

- Day 15.01-20: 100 kPa (Unloading)

- Day 20.01-30: 50 kPa (Unloading)

If you require more parameters, assume a reasonable value and state it in your solution.

Hints -

First define an insitu analysis;

For loading and unloading define a stress function using X-Y Stress (negative stress means downward stress);

Use Elastic-Plastic (PWP change) Material model to simulate the clay;

Assume an isotropic clay.

Create one analysis and apply the stress function to simulate the step loading;

Please note that the water table is always at the top of the sample;

Please note that there will be two porous stones at the top and bottom of the sample for providing a drainage to the sample. Therefore, the pore-water pressure at the top of the sample will always be Zero kPa and the pore-water pressure at the bottom end of the sample will be always Height of the sample times by unit weight of the water that is required to be defined using a pressure head boundary condition; and

Use the following hydraulic conductivity and volumetric water content functions:

Matric Suction (kPa)	VWC
0.1	0.49937038
0.13869189	0.49880775
0.19235439	0.49774441
0.26677993	0.49574165
0.37000212	0.49199441
0.51316292	0.48507012
0.71171532	0.4725662
0.9870914	0.45089782
1.3690157	0.41589427
1.8987137	0.3652617
2.6333618	0.30245663
3.6522591	0.23741972
5.065387	0.18067006
7.0252808	0.13701398
9.7434944	0.10562106
13.513436	0.083479517
18.742039	0.067712276
25.993688	0.05622451
36.051136	0.047627085
50	0.041021043

 

Matric Suction (kPa)	Water X-Conductivity (m/sec)
0	1.00E-07
0.1	9.74E-08
0.13869189	9.58E-08
0.19235439	9.33E-08
0.26677993	8.92E-08
0.37000212	8.28E-08
0.51316292	7.32E-08
0.71171532	5.94E-08
0.9870914	4.18E-08
1.3690157	2.36E-08
1.8987137	9.82E-09
2.6333618	2.94E-09
3.6522591	6.68E-10
5.065387	1.27E-10
7.0252808	2.17E-11
9.7434944	3.55E-12
13.513436	5.67E-13
18.742039	8.96E-14
25.993688	1.41E-14
36.051136	2.21E-15
50	3.46E-16

2. Tasks -

Model the above problem using Geostudio 2020 and prepare a report with the following components:

a) Model Geometry (Max. 1-page image).

b) Boundary conditions and analysis type (Max. 2-page text/graph/image).

c) The shape of the deformed sample (Max. 1-page image).

d) Draw a graph of the displacement of the top centre of the soil layer with time (day).

e) Draw a graph of the excess pore-water pressure at the mid-layer centre of the sample over time (day).

f) Draw a graph of the effective stress at the mid-layer centre of the sample over time (day).

Please note that, the report must be self-explaining and you should describe the results. Submitted reports with no explanations will not receive the required mark to pass this assignment.

The report must be submitted in the MS Word file including the answers to the above questions.

You should also upload your GeoStudio into a Google drive and share the link in the MS Word repot file.