CASE STUDY GA110-1-9412
 |
SETTLEMENT OF
AN OFFICE
BUILDING BUILT
OVER LANDFILL |
Clarkston, Georgia
Engineered by:
Sailors Engineering, Inc.
Atlanta, Georgia
Installed by:
Atlas Piers of Atlanta
Alpharetta, Georgia
|
SETTLEMENT
OF AN OFFICE BUILDING
BUILT OVER LANDFILL
The building at the right is the subject of this report. The fill material
and the major
settlement were found at this northeast corner.
THE PROBLEM!
Description of Site:
This two-story office building was built over a pit containing 10 to 12 feet of fill
soil, wood, organics and other debris. Standard Penetration Test of the area revealed very
loose soil. Blow counts in the area of settlement were on the order of one or two blows
per foot per ASTM D-1586-67.
Description of Structure:
The building faces west and is of standard frame construction with a brick veneer
resting upon a reinforced concrete slab. The exterior grade beam ranged from 4 to 5 feet
tall in the area of the settlement. This suggests that the builder unsuccessfully
attempted to reach suitable soil below the landfill pit. The interior floor was measured
to have downward settlement of approximately 2-1/2 inches at the northeast corner. Large
cracks were present in the masonry above the windows on the north wall and at the rear
doorframe at the east side. (The photo on the previous page shows the northwest corner
with a masonry fracture on the north side, and the view above shows the northeast corner.)
Separations between the door and window framing and the masonry were also noted in the
same areas. The interior showed significant distress in the walls on the second floor.
Special Techniques Required:
Each Atlas Pier Pipe Section within the area
of fill had a 4-inch sleeve pipe installed over the Pier Pipe. The purpose of the
modification sleeve was to provide enhanced stiffness and rigidity to the Pier, and to
strengthen the segmented joints in the Pier Pipe.
PROJECT SUMMARY |
|
| Engineer: |
Sailors
Engineering, Inc. |
| Repaired
By: |
Atlas
Piers of Atlanta,
Alpharetta, Georgia |
| Piers
Required: |
Nine (9) |
| Part
Number: |
AP2(PA)-3500.160M |
| Average
Depth: |
Thirty-Nine
Feet (39') |
| Amount
of Lift: |
1/2"
to 2-1/2" |
| Driving
Force: |
75,500
lb. (Avg.) |
| Lifting
Force: |
32,445
lb. (Avg.) |
| Factor
of Safety: |
2.3:1
(Working Load)
2.8:1 (Ultimate Load) |
|
The sketch above details the scope of
the project and as-built configuration. At right are photos of the north wall showing the
recovery achieved from the underpinning.
|
|
| SUCCESS! |
|
|
|
| Detail of
the masonry separation on the north side of the structure is shown above, note that after
restoration the recovery was nearly 100 percent The recovery at the entrance on the east
side of the structure was nearly perfect! |
|
|
The
recovery at the entrance on the east side of the structure was nearly perfect! |
Atlas Piers |
INSTALLATION
SUMMARY |
Pier
Installation Log
| Location |
Lifting
Force,
pounds |
Driving
Force,
pounds |
Ultimate
Cap.,
pounds |
Working
F.S. |
Ultimate
F.S. |
| Pier #1 |
32,445 |
74,610 |
90,000 |
2.3 : 1 |
2.8 : 1 |
| Pier #2 |
32,445 |
82,900 |
90,000 |
2.6 : 1 |
2.8 : 1 |
| Pier
#3 |
32,445 |
74,610 |
90,000 |
2.3 : 1 |
2.8 : 1 |
| Pier #4 |
32,445 |
82,900 |
90,000 |
2.6
: 1 |
2.8 : 1 |
| Pier #5 |
32,445 |
70,465 |
90,000 |
2.2 : 1 |
2.8
: 1 |
| Pier
#6 |
32,445 |
70,465 |
90,000 |
2.2
: 1 |
2.8
: 1 |
| Pier #7 |
32,445 |
74,620 |
90,000 |
2.3 : 1 |
2.8 : 1 |
| Pier #8 |
32,445 |
74,610 |
90,000 |
2.3
: 1 |
2.8 : 1 |
| Pier
#9 |
32,445 |
74,610 |
90,000 |
2.3 : 1 |
2.8
: 1 |
|
Results
Approx.
Lift
inches |
Depth to
Bearing
feet |
| 2" |
47' |
| 2" |
33' |
| 2-1/4" |
36.5' |
| 2-1/2" |
36.5' |
| 2-1/2" |
40' |
| 2" |
40' |
| 1" |
40' |
| 1/2" |
40' |
| 1/4" |
39' |
|
|
|
|
THE
Solution! |
Atlas Piers |
|
|
|
