Geoscience Reference
In-Depth Information
application 11.4
Consider a stiff wall which forms the side of a building pit; its length is 14 m
(see Fig 11.12). An anchor, every 5m, keeps the wall on its place. At a certain
moment the anchor is prestressed, which induced the anchor force F . Sketch the
distribution of induced horizontal stresses on the wall. Calculate the value of F .
The soil is characterised by
= 30 o , c = 0.
Advice: Assume rotation point at B and a rigid wall. Determine the horizontal
earth pressures at the wall when allowing for a small rotation of the wall. Find F by
considering the moment around B or by horizontal equilibrium (answers may
differ; in fact the rotation point is a little higher).
= 16 kN/m 3 ,
application 11.5
A combi-wall is popular for building pits. A concept design is handed over
without much details (see Fig 11.13). The sheet piling is a Larsson 22. What will
happen when the free water suddenly drops by 3 m? Is the design robust?
0.0
0.0
0.0
0.0
0.0
0.0
0.0
-3.0
-3.0
-3.0
-3.0
-3.0
-3.0
-3.0
3.0 m
3.0 m
3.0 m
3.0 m
3.0 m
3.0 m
3.0 m
anchor
anchor
anchor
anchor
anchor
anchor
anchor
8.0 m
8.0 m
8.0 m
8.0 m
8.0 m
8.0 m
8.0 m
sheet piling
sheet piling
sheet piling
sheet piling
sand
sand
sand
sand
sand
sand
sand
anchor
anchor
anchor
anchor
anchor
anchor
anchor
-12.0
-12.0
-12.0
-12.0
-12.0
-12.0
-12.0
-16.0
-16.0
-16.0
-16.0
-16.0
-16.0
-16.0
tubular
pile
tubular
pile
tubular
pile
tubular
pile
tubular
pile
tubular
pile
tubular
pile
clay
clay
clay
clay
clay
clay
clay
sand
sand
sand
sand
sand
sand
sand
(a) vertical cross-section (b) helicopter view
Figure 11.13 A combi-wall
application 11.6
In Fig 11.7b a stress diagram is presented caused by an anchored rigid embedded
wall. Sketch the stress diagram, if the anchor is prestressed. How much does the
stability factor change because of prestressing?
 
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