The International Information Center for Geotechnical Engineers

New Pre-Engineered, Code Compliant Fence Post Foundation Delivers Results To DHL

Security is a top priority in the shipping industry. So when plans for DHL's new 290,000 square foot distribution facility in
Allentown, Pennsylvania called for 3,450 linear feet of retaining wall along the perimeter of this 72 acre site, the chain link
fencing above the walls quickly became a topic of concern for the wall contractor and construction manager. "It is rarely
understood by the client that fencing cannot be installed on top of perimeter walls without careful design considerations,"
states Andre De Carville, Vice President of Pickering Valley Landscape, Inc. "The grading plan noted a fence above every
wall but did not provide a structural detail showing how to integrate our work with that of the fence contractor."

Segmental Retaining Walls (SRW) most appealing quality is how the dry stacked block face and geosynthetic reinforcement
(Geogrid) combine to form a retention system capable of holding back steep slopes and handle heavy loads. A limitation,
however, is that the dry stacked wall face has minimal resistance to overturning in the upper two or three courses when a
point load is applied to the block. This is precisely what happens when a load is placed on a fence post in close proximity
to the wall face. That, along with tearing through the embedded soil reinforcement behind the wall with an auger, can
greatly affect both the integrity of the wall and fence structures.

New Pre-Engineered Product Offers A Solution

At this point, Strata Systems, the manufacturer of an advanced, pre-engineered product called Sleeve-It™ 1224R was
contacted. This fence-ready and code compliant design was created to address the very issues the construction team was
concerned about. Strata provided test reports and additional calculations to the project engineer of record explaining how
the Sleeve-It approach meets or exceeds the building code requirements for railings along the sides of elevated walking
surfaces. A Strata technical representative was also made available for further on-site consultation.

With only 10 days from the bid award date to provide a final wall design and 120 days from ground breaking for the new
facility to be fully operational there was no time to waste. "We recommended the use of the pre-engineered Sleeve-It
system to the construction manager, Opus Corporation, for integrating the chain link fence with the SRWs." says wall
design engineer Bart Shippee PE. "The Sleeve-It product test data translates exceptionally well for a 6' tall chain link fence
with 10' post spacing addressing the IBC load criteria for railings in commercial applications."

A Simple And Effective Installation Process

In all, over 350 Sleeve-It units were installed during wall construction. Sleeve-It 1224R is typically pre-assembled at the
material staging area for the wall, then set in place with desired post spacing when the wall has reached approximately
24" from the top of wall. Sleeve-It is stocked by the pallet and sold by the box. "I was not only amazed with how the
Sleeve-It product works but that I was able to fit two pallets in the back of my pickup truck rather than pulling a trailer with
12' sections of ADS pipe tied down", commented Pickering field supervisor Ron Buchanan. "This was our first project with
Sleeve-It and since there was virtually no learning curve required, our wall production rate was not slowed at all."

When the wall construction was completed, the fence installer arrived to complete the perimeter fencing. "We showed up
ready to auger holes and much to our surprise the holes were already there," mentioned Scott Risbon with Earthcare
Landscaping Inc. "There was even a lid on every one that kept the topsoil from filling the holes during several rain storms
after the wall was built."

Results

Strata's Sleeve-It design negated the need for a 36" offset of the fence on top of the wall. This 3-foot real estate savings
actually translated into a total area savings of 10,000 square feet for the entire project. Traditional methods of integrating
a railing at the wall face would have added 2-3 times greater cost to this portion of the project. The end result was a well
secured facility completed on time, within budget, and able to deliver the peace of mind that goes with it.

Attention Editors: The following is the actual building code that applies to this application.

SIDEBAR -

The 2006 International Building Code, Section 1013.1 and 1013.2 requires a minimum 42" railing near the open sides of
elevated walking surfaces that exceed 30" in height. Section 1607.7.1 states that handrail assemblies and guards shall be
designed to resist either a 200 lb concentrated load or a 50 plf load, application dependent. This load is required to be
safely transferred through the supports of the fencing or guard system and into the structure (foundation). Most
municipalities in the United States have adopted these building codes as their own.

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Wednesday, 21 November 2012 15:48

Spaulding Dam

Spaulding dam is an arch dam with a constant radial curvature. The geologic area consists of igneous intrusive rocks. In the picture below you can see the spillway which is not part of the dam structure. This is the site behind the spillway. You can easily see that there is a small canyon. This canyon, which is very deep but is not shown in the picture, was formed by the erosion of the water which comes out of the spillway, in the direction shown in the picture. The speed and the quantity of the water are the cause of this erosion. You can see that concrete was poured on the rock surface, in an attempt to minimize the erosion which could destroy the rock below the spillway and lead to the destruction of the spillway and of the reservoir. 

 

References:

Information collected during the field trip in the Sierra Nevada, as part of the "Engineering Geology" course curriculum, instructed by Professor N. Sitar, Department of Civil & Environmental Engineering, University of California at Berkeley.

Please refer to the site when you use this material.

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Wednesday, 21 November 2012 15:47

Close picture of dental concrete surface in dams

This is just a detail of the surface of the dental concrete from the construction of the Auburn Dam. You can easily observe that the surface is very rough. This will help in the binding of the new concrete with the old one. The non-existence of smooth surfaces of old with new concrete in concrete dams is a very important issue, because these surfaces consist planes of weakness under the applied load. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

References: 

Information collected during the field trip in the Sierra Nevada, as part of the "Engineering Geology" course curriculum, instructed by Professor N. Sitar, Department of Civil & Environmental Engineering, University of California at Berkeley.

Please refer to the site when you use this material.

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This photo is from the Auburn Dam construction site, California, USA. According to the design, the thrust of the abutment was normal to the foliation, which is of great importance for the stability of the dam. The stiffness of the material in the perpendicular direction was much greater due to the orientation of the joints. However in the third direction, which is perpendicular to the aforementioned and to the orientation of joints (normal to the plane of of the screen) the stiffness would have been even greater. 

References: 

Information collected during the field trip in the Sierra Nevada, as part of the "Engineering Geology" course curriculum, instructed by Professor N. Sitar, Department of Civil & Environmental Engineering, University of California at Berkeley.

Please refer to the site when you use this material.

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Wednesday, 21 November 2012 15:45

Auburn Dam

The Auburn Dam would be the largest concrete arched dam in the world. It was a project of the Bureau of Reclamation. The purpose of this dam was hydroelectricity production, recreation, water supply and most importantly flood control of the Sacramento valley. The dam would have: 

Structural height: 800ft 

Crest length: 4000ft 

Concrete volume: 6.5 million cubic yards 

In 1965, the project received the Congress’s Authorization and geologic and other investigations began and finally suggested the arch concrete dam type. With the yellow arrow, you can see the flip bucket spillway at the left abutment of the dam. Also you can see the foundation of the left abutment of the dam. 

The 1971 San Fernando earthquake and the 1975 Oroville Earthquake had initiated more extensive geotechnical investigations. As a result of these investigations, a fault, which was part of the Foothill fault system, was identified and for that reason the design has changed to a curved gravity dam. 

The construction stopped because the scenario of failures increased the public awareness and stopped the project. A failure of this dam would cause also the failure of the Folsom dam and would finally flood the city of Sacramento. Even though, this scenario was not so possible, the probability of the existent truncated fault to cause a movement of 8-12inches could not be discounted. 

For that reason, in 1975, the construction of the dam stopped. 

With the red arrow is indicated the embankment. The embankment was overtopped during a flood for which the bypass tunnel was not designed for. . The tunnel, since then, has been leading the waters through the mountain. This tunnel was designed probably for a 20-year flood, and since so many years passed, the fact that it finally failed once should not be considered a failure. 

References: 

Leaflet of the Bureau of Reclamation Mid Pacific region about the Auburn-Folsom Unit and information collected during the field trip in the Sierra Nevada, as part of the "Engineering Geology" course curriculum, instructed by Professor N. Sitar, Department of Civil & Environmental Engineering, University of California at Berkeley.

Please refer to the site when you use this material.

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Wednesday, 21 November 2012 15:44

The Dam of Stratos

Construction: started in 1981 and ended in 1988. 
Length of the crest: 1900m 
Height: small height of 26.0m.

It is an earth fill dam with a core of clay. It is founded on gravel and sand and in its base there is a cut off diaphragm wall. The diaphragm wall has a depth of 25m from the surface and is used to decrease the leaking below the dam, which may create damages to the dam.

Below you may find information on deformation monitoring and photos of the dam.

These are three spots from which measurements of the deformations of the dam are taken. The one is not used anymore because of the small building constructed. The other two are used to measure with geodetic equipment the deformation of each side of the dam. The horizontal and vertical deformation is calculated. Maximum vertical deformation on the crest of the dam: 22mm.

This is the view of the dam from where the measurements are taken. You may see the points in each side of the dam where the deformation is measured.

Please refer to the site when you use this material.

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Wednesday, 21 November 2012 15:43

The Kastraki Dam, Greece

The dam of Kastraki is an earth dam. In the bottom of the picture you can see its spillway. The behavior of the dam is monitored since construction. The instrumentation used consists of:

  • Inclinometers 
  • Piezometers 
  • Rod settlement gages

More photos of its lateral spillway. 

 

Please refer to the site when you use this material.

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