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Why choose geopier Foundation Company?
With Geopier Foundation Company’s® expert designs and PCI’s seasoned constructors, we can work with your difficult soil problems to give you a design-build solution to get your project out of the ground very quickly and efficiently. Even the best built structure is unstable without a solid support system.
What is the geopier® system?
The Geopier® systems uses Intermediate Foundation® technology that fills the void between shallow and deep foundations and can take the place of traditional soil replacement methods, as well. We know if you are contemplating building on poor or unsuitable soil there are many questions.
What is the geopier solution for perimeter differential settlement control?
GEOPIER SOLUTION Perimeter Differential Settlement Control Fill Soft Clay Firm to V. Stiff Clay GEOPIER SOLUTION Bearing Capacity –Edge Instability V. Soft to Firm Clay Firm to V. Stiff Clay Geopier FS for Geopier-reinforced soil = 1.30
What is the geopier element?
This means that the lateral stresses of the soil can be as much as 2 to 3 times greater than originally imparted by the soil. Due to this high degree of vertical compaction and lateral confinement, the Geopier element provides stiffness that can control settlement of structures very efficiently.
How do Geopiers work?
Geopier System (Rammed Aggregate Piers – RAPs) is a ground improvement method that prestrains and prestresses the soil using soil “replacement” and soil “displacement” technology to strengthen soft soil and loose soil with very dense, stiff, rock columns constructed by heavy equipment crowd force and vertical impact ...
What is Rammed aggregate piers?
Geopier Rammed Aggregate Pier® (RAP) systems are ground improvement technologies that create a densified column of aggregate surrounded by a stiffened matrix soil. These systems are ideal for nearly all soil types and applications.
How do aggregate piers work?
Aggregate Piers are made by pre-drilling a hole into the soil of foundation, lifting the aggregates, and then tamping them into the hole. This lifting and tamping process is repeated until the void is filled with aggregate, and each additional ramming step creates a tighter, sturdier foundation.
How much are rammed aggregate piers?
“Based upon job experience, labor will cost $300 to install one aggregate pier; therefore, the total labor cost to install 100 aggregate piers can be estimated at $30,000.”
How strong is rammed earth?
As the walls dry and harden (ideally in warm weather), the compression strength of the rammed earth increases to a maximum of 4.3MPa (620 psi). This is less than concrete but sufficiently strong for domestic buildings. Cured rammed earth has a high thermal mass.
What is a major benefit of aggregate piers?
The aggregate pier system is extremely effective to reinforce soft clays and silts or to significantly improve man-made fills. When installed with a down-hole vibratory probe, aggregate piers can also be used to improve loose, silty sands with a process called vibro-replacement.
What are Geopiers made of?
The Geopier® Systems are made up of Rammed Aggregate Pier® elements.
What is a helical pier?
A helical pier is a foundation pin made of steel that contains helices just like screws. It is driven into the soil, to depths below the frost line by use of a hydraulic system.
What are Geopiers made of?
The Geopier® Systems are made up of Rammed Aggregate Pier® elements.
What is a helical pier?
A helical pier is a foundation pin made of steel that contains helices just like screws. It is driven into the soil, to depths below the frost line by use of a hydraulic system.
What is stone piling?
The stone, or gravel, pile is mainly used as a means of strengthening sub-strata by introducing a series of stone columns using vibration or jetting methods which compact the ground around the stone and replace the void created with a compacted stone column (see Fig. 9.33).
What is rigid inclusion?
Rigid inclusions is a ground improvement method using high deformation modulus columns constructed through compressible soils to reduce settlement and increase bearing capacity. Ground improvement efficiency depends on the stiffness relationship between the soil and the columns.
What is geopier system?
Geopier systems can be used to improve very soft to stiff clay and silt, organic silt and peat, loose to dense sand, mixed soil layers, uncontrolled fill, and soils below the ground water table. When organic or peat soils are encountered, cement treated aggregate can be used to stiffen the pier in the organic zone or throughout the entire pier, if needed.
What is a geopier rammed aggregate pier?
Geopier Rammed Aggregate Pier® (RAP) systems consist of a very stiff, vertically rammed, compacted aggregate shaft placed within the soil needing improvement. The high-energy impact compaction imparted on the aggregate within the Geopier element also produces significant lateral pre-straining and pre-stressing of the adjacent matrix soils. The lateral stress in the matrix soil surrounding the Geopier element approaches Kp, the coefficient of passive earth pressure. This means that the lateral stresses of the soil can be as much as 2 to 3 times greater than originally imparted by the soil. Due to this high degree of vertical compaction and lateral confinement, the Geopier element provides stiffness that can control settlement of structures very efficiently.
What is GP3 impact?
GP3 and Impact systems are alternatives to overexcavation and replacement of weak soils or fills , and deep foundation systems such as piles or drilled shafts. GP3 and Impact elements are used to support commercial, industrial, transportation and residential applications, including buildings up to 20 stories tall, industrial tanks, heavily-loaded warehouse floor slabs, MSE walls and embankments, and other transportation structures. Geopier systems are also used to provide liquefaction mitigation, uplift resistance and increased resistance to lateral loads.
How much stronger is GP3 than stone?
Over the stress ranges tested the GP3 elements were 2 to 9 times stiffer than the stone columns and under a test embankment the stone column reinforced soils settled 3 times more than the Geopier reinforced soil. The end result was that because individual elements are stiffer than stone columns they are more effective in controlling settlement.
Why are footings larger than required?
Footings may be larger than required for structural reasons which will lower the final area ratio. However, the lower area ratio by itself will not affect the performance of the footing. Requiring a minimum area ratio will unnecessarily increase the number of elements required for the project and add increased cost.
Can water accumulate in footings?
Also, consistent with good site management practice, water should not be allowed to accumulate in the footing excavation prior to concrete placement. If the footing cannot be constructed immediately after excavation, a mud mat may be used. 17.
Who performed the comparison of stone column and rammed aggregate pier soil reinforcement?
A direct comparison of the two systems is provided in the reference paper summarizing a FHWA-funded research project performed by Dr. David White at Iowa State University – Embankment Support: A Comparison of Stone Column and Rammed Aggregate Pier Soil Reinforcement.
How to contact Geopier?
Work with engineers worldwide to solve your ground improvement challenges. For more information call 800-371-7470, email [email protected], or visit geopier.com.
How to validate a geopier?
To validate the Geopier design, a modulus test was performed on a 20-inch test pier with a 10-ft shaft length and 20-inch diameter, 2-ft thick concrete cap. A maximum load of 52.7 kips was applied directly to the concrete cap resulting in a maximum top of pier stress of 24.2 ksf which is 150% of the Geopier design stress and approximately 485% of the design footing bearing pressure of 5.0 ksf. As observed in Figure 6, the total deflection at the maximum top of pier stress was approximately 0.66-inch. At the design top of pier stress of 16.1 ksf, the total deflection was 0.29-inch resulting in a Geopier stiffness modulus value of 386 exceeding the design value of 250 pci. These results confirm that the design meets the projects' settlement requirements and provides added assurance for performance beyond the anticipated loads. Note that had the test been stopped at twice the design bearing pressure (i.e. 10.0 ksf), the settlements would have been unconservatively underestimated by a factor of two (0.14-inch vs 0.29-inch).
How to find total foundation settlement?
The total foundation settlement is estimated using Equation 1 by summing the estimated settlement in the upper zone and the estimated settlement in the lower zone: S
What is the upper zone of geopier soil?
Geopier soil reinforcing elements are designed using a two-layer model to control foundation settlements (Figure 1). The “upper zone” is defined by the depth of the Geopier elements which is a combination of the shaft length (Hs) and bulb
What is the simplified expression for geopier stress?
m, the following simplified expression for Geopier stress is established: qg = . Eq.7. For longer piers (e.g. greater than about 15 feet), and foundations with a wide footprint area of influence (e.g. tanks, grain bins, etc.), upper zone settlements may be evaluated using a composite modulus approach where settlement within the upper zone of soil is estimated using conventional settlement calculations as shown in the following equation (Terzaghi et al. 1996): S
What is geopier soil reinforcement?
Geopier soil reinforcement is used to reinforce and stiffen compressible foundation soils and increase the time-rate of settlement in order to control post-construction settlement magnitudes . The design methodology utilizes conventional settlement and radial drainage approaches with minor modifications based on advanced research to determine the Geopier element spacing required to control settlement and meet project settlement criteria.
What is Geopier RaP?
The Geopier RaP soil reinforcement settlement control design methodology is based on a two-layer settlement approach as initially described by lawton et al. (1994), lawton and Fox (1994), and Wissmann et al. (2002). The installation of Geopier elements within the Geopier-reinforced zone, referred to as the upper zone, creates a stiffened, engineered zone with reduced compressibility that reduces settlement of embankments and transportation related structures. The settlement below the Geopier reinforced zone, referred to as the lower-zone, is evaluated using conventional geotechnical analysis approaches. The total settlement (Stot) of the transportation structures is evaluated as the sum of the upper zone settlement (Suz) and the lower zone settlement (SlZ):
What is geopier made of?
The Geopier®Systems are made up of Rammed Aggregate Pier®elements. With time, the Geopier System gained popularity with cost and schedule benefits.
What does KSF stand for in geopiers?
Top of Geopier Stress (ksf) Deflection (in) Design Stress Deflection
What causes a spike in a piezometer?
Spike Caused by Driving of Pile within 5 ft of Piezometers Gradual Rise in Pore Pressure Caused by General Rise in Groundwater Elevation
Why did Geopier stop the first test?
Geopier actually had to perform (2) 48-hour tests due to rain. They stopped the first test after 24 hours because the location was low on the site. Water started to enter the stone columns and out of an abundance of caution, Geopier stopped the test. They brought in gravel to create an elevated pad where they assembled a new test frame. Geopier passed all the tests with flying colors. The City accepted the results and approved 851 W Grand to use Geopier RAPs to stabilize the soil.
How deep are geopier raps?
The Geopier RAPs were 28′ deep and 30″ in diameter. Both longer and wider than the Helitech design. Geopier was also about $100,000 more expensive than Helitech for 300 rammed aggregate piers.
Why did we have to test the ground improvement system?
However, their approval had conditions. We had to test the ground improvement system to ensure it met the design strength. Testing the system would add considerable time, but it ultimately saved us from making a catastrophic mistake. Read on….
Does Chicago recognize Helitech?
In 2016, the City of Chicago did not recognize all ground improvements systems. Unbeknownst to me, Geopier had previously conducted extensive testing on their Rammed Aggregate Piers and was approved by the City to use their ground improvement system. Helitech was unproven, and the City required them to submit their system to the Committee on Standards and Tests to be evaluated.
Does Chicago recognize stone columns?
The Geopiers worked great and exactly as advertised. However, the City of Chicago does not formally recognize “stone column” ground improvement systems. The purpose of this article is to provide a very detailed analysis and discussion of the steps we took in order to effectively use a ground improvement system.
Can you load a geopier rammed aggregate pier?
To be clear, ground improvement systems are not caissons. You cannot individually load a Geopier Rammed Aggregate Pier or Helitech Vibratory Stone Column. It is simply a system to improve soil stability. And in our case at 851 W Grand, improving the soil allowed us to build the building on traditional shallow spread footings. Our project was the first 6-story residential building in the Chicago CBD constructed on Geopier RAPs.
