Basement
3 - basement
3 - Basement
1
Quick Revision
1.1 Problems arising from basement construction
a.
Excavation method.
b.
Surface and ground water control
c.
Lateral stability of basement excavation.
d.
Stability of adjoining building.
1.2 Ground water control - dewatering
a.
Open Sump Pumping
b.
Wellpoint System.
c.
Shallow-Bored Well System
d.
Deep-Bored Well System
1.3 Basement Excavation
a.
Open excavation
b.
Sheet pile cofferdam
Supported with raking struts
Supported with struts and walings
Supported with ground anchors
Ground support and ground water control for deep excavation
Cut off wallings:
c.
Thin grouted diaphrage
d.
Mixed in place wall
e.
Ground treatment
f.
Circular cofferdam
g.
Diaphrage wall
1/11
3 - basement
2.
Cut-off wallings
2.1
Thin grouted diaphragm
A series of touching universal beams or columns are driven into the ground to the required depth. A grout injection pipe is fixed to the web the section and this is connected to a group pump at the ground. As the sections are withdrawn the void created is filled with cement grout to form the thin membrane.
This is a non-structural wall and services only as a cut-off wall. It is suitable subsoil of silt, sand and gravel. 2.2
Thin grouted diaphragm (Source: R. Chudley)
Mixed-in-place wall
A hollow churn drill is drilled into the ground.
Intrusion grout is pumped through the hollow kelly bar during the drilling operation. When the required depth is reached, the auger rotation is reversed and withdrawn while grout injection continues. The grout is thus mixed with the existing soil to form a mixed-in-place pile. The above process is repeated with the piles being cast against each other until the whole wall is formed.
Mixed-in-place pile
(Source: Jufri & Wellmen)
2/11
3 - basement
2.3
Ground treatment
The major disadvantage of
3 - Basement
1
Quick Revision
1.1 Problems arising from basement construction
a.
Excavation method.
b.
Surface and ground water control
c.
Lateral stability of basement excavation.
d.
Stability of adjoining building.
1.2 Ground water control - dewatering
a.
Open Sump Pumping
b.
Wellpoint System.
c.
Shallow-Bored Well System
d.
Deep-Bored Well System
1.3 Basement Excavation
a.
Open excavation
b.
Sheet pile cofferdam
Supported with raking struts
Supported with struts and walings
Supported with ground anchors
Ground support and ground water control for deep excavation
Cut off wallings:
c.
Thin grouted diaphrage
d.
Mixed in place wall
e.
Ground treatment
f.
Circular cofferdam
g.
Diaphrage wall
1/11
3 - basement
2.
Cut-off wallings
2.1
Thin grouted diaphragm
A series of touching universal beams or columns are driven into the ground to the required depth. A grout injection pipe is fixed to the web the section and this is connected to a group pump at the ground. As the sections are withdrawn the void created is filled with cement grout to form the thin membrane.
This is a non-structural wall and services only as a cut-off wall. It is suitable subsoil of silt, sand and gravel. 2.2
Thin grouted diaphragm (Source: R. Chudley)
Mixed-in-place wall
A hollow churn drill is drilled into the ground.
Intrusion grout is pumped through the hollow kelly bar during the drilling operation. When the required depth is reached, the auger rotation is reversed and withdrawn while grout injection continues. The grout is thus mixed with the existing soil to form a mixed-in-place pile. The above process is repeated with the piles being cast against each other until the whole wall is formed.
Mixed-in-place pile
(Source: Jufri & Wellmen)
2/11
3 - basement
2.3
Ground treatment
The major disadvantage of