Sijil Tinggi Muamalat 2 - Pasaran Modal Islam : Khairul Anuar Ahmad (KUIS)
MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF....
Transcript of MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF....
BRACED EXCAVATION DESIGN
MUHAMMAD AZRIL HEZMI
PROF. KHAIRUL ANUAR KASSIM
PROF. Ir. DR. RAMLI NAZIR
INSPIRING CREATIVE AND INNOVATIVE MINDS
CONCEPT
• Consist of sheet piles driven into the soil to form sides of an excavation
such as construction of bridge piers and abutments.
• As excavation proceeds within the area enclosed by the sheet piles, struts
are added to keep the sheet pile in place.
• Displacement gets larger at depth.
• Critical design element are the loads on the struts which are usually
different because of different lateral loads at different depths, the time
between excavations and the installation procedures.
Contd…
• The analysis for the forces and deflection in braced excavation should ideally
consider the construction sequence, and numerical methods such as the finite
element.
• Semi empirical methods are often used in the design of shallow braced
excavation and also as a basic design of deep braced excavation.
• In the soft and Normally Consolidate soil, heaving may occurs at the base of
the excavation.
• Bjerrum and Eide (1956) suggested that the excavation could be view as
afooting and embedment depth Ho.
Contd….
so
ucheave
qH
cNFS
+=
γ)(
• The factor of safety against the bottom heave is given by:-
• For practical purposes the value of Nc is given by:-
L
BI
B
HifIN
and
B
Hfor
B
HN
co
cc
ooc
16.084.0,5.2...........9
5.2..........2.016
+=>=
≤
+=
Contd….
• If FOS < 1.5, the length of embedment should be extended below the base of
excavation for stability.
• The value of coefficient m = 1 except that when the soil below excavation is
deep, soft and normally consolidated clay, m value is approximately 0.4(FOS
heave).
• The strut load at each depth is assumed to be a hinge connection between strut
and sheet pile. Thus solution is using static equilibrium.
• Displacement of the wall is important in design consideration as adjacent
structire may affected.
• However it is better off to solve using numerical method.
PROCEDURE FOR ANALYSIS
• Check stability against bottom heave. If FOS < 1.5 the wall should be
extened below base.
• Determine the lateral stresses on the wall according to soil type.
• Treat the connections of the wall to the struts as hinges.
• Draw a free body diagram at each level of excavation.
• Solves the forces in the stuts using the static equilibrium equations on
each free body diagram.
Examples