MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF....

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BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE MINDS

Transcript of MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF....

Page 1: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE

BRACED EXCAVATION DESIGN

MUHAMMAD AZRIL HEZMI

PROF. KHAIRUL ANUAR KASSIM

PROF. Ir. DR. RAMLI NAZIR

INSPIRING CREATIVE AND INNOVATIVE MINDS

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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.

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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.

Page 4: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE
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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

+=>=

+=

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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.

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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.

Page 8: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE

Examples

Page 9: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE
Page 10: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE
Page 11: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE
Page 12: MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR ......BRACED EXCAVATION DESIGN MUHAMMAD AZRIL HEZMI PROF. KHAIRUL ANUAR KASSIM PROF. Ir. DR. RAMLI NAZIR INSPIRING CREATIVE AND INNOVATIVE