Hydro-Mechanical Properties of an Unsaturated Frictional Material
Hydro-Mechanical Properties of an Unsaturated Frictional Material
Hydro-Mechanical Properties of an Unsaturated Frictional Material
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10.6. SUMMARY 203<br />
Bearing capacity (kPa)X<br />
1000<br />
800<br />
600<br />
400<br />
200<br />
0<br />
Saturated Reihe7 (S=1.0)<br />
Suction Reihe1 2 kPa<br />
Suction Reihe2 3 kPa<br />
Suction Reihe3 4 kPa<br />
Dry Reihe4 (S=0)<br />
Prediction Reihe5<br />
0 2 4 10 66<br />
Suction (kPa)<br />
Figure 10.8: Comparison <strong>of</strong> experimental <strong>an</strong>d predicted results <strong>of</strong> bearing capacity<br />
the measurements. Predicted values are only slightly decreasing, which is not consistent with<br />
theory. In theory mech<strong>an</strong>ical behavior <strong>of</strong> saturated soils is equal. The experimental results<br />
are overestimated by the predicted results. Further investigation on bearing capacity <strong>of</strong> strip<br />
footings on unsaturated soils <strong>an</strong>d the development as well as validation <strong>of</strong> <strong>an</strong> equation for<br />
predicting unsaturated soils bearing capacity is needed.<br />
10.6 Summary<br />
Bearing capacity <strong>of</strong> a surface model footing was carried out on saturated as well as unsaturated<br />
s<strong>an</strong>d in a fundament box. According to Gussm<strong>an</strong>n (1986) failure mech<strong>an</strong>ism <strong>of</strong> smooth footing<br />
was found below the footing. The results show, that the bearing capacity is improved when<br />
dealing with unsaturated s<strong>an</strong>d. Similar to the influence <strong>of</strong> suction on the stiffness <strong>of</strong> Hostun<br />
s<strong>an</strong>d, the bearing capacity is increasing first with increasing suction <strong>an</strong>d is th<strong>an</strong> after reaching<br />
<strong>an</strong> optimum decreasing with further increase in suction. At all the bearing capacity was found<br />
to be 2.5 to 4 times higher then for the saturated specimen.<br />
The approach suggested by V<strong>an</strong>apalli & Mohamed (2007) was successfully applied to<br />
the derived experimental results. Further experimental investigation <strong>of</strong> bearing capacity on<br />
unsaturated Hostun s<strong>an</strong>d is necessary in the residual zone to validate <strong>an</strong>d modify the approach<br />
given by V<strong>an</strong>apalli & Mohamed (2007). The difference between measured <strong>an</strong>d predicted<br />
results in the residual zone has to be reduced. Also the predictions <strong>of</strong> bearing capacity<br />
<strong>of</strong> water <strong>an</strong>d air saturated specimen are not in the same r<strong>an</strong>ge when using the model by<br />
V<strong>an</strong>apalli & Mohamed (2007). Theoretically water <strong>an</strong>d air saturated specimen show similar<br />
mech<strong>an</strong>ical behavior.
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