Proper Modulus Testing Procedures for Geopier Rammed Aggregate Pier ...
The focus of this month's Brief is a "back-to-basics" ground improvement topic that underscores the fundamentals of proper field modulus testing of Geopier Rammed Aggregate Pier ® systems. Note that this Brief only applies to non-rigid Aggregate Pier (AP) elements, not rigid inclusions. For further information on rigid inclusion testing , please refer to our April 2021 and August 2022 ...
Design methods used to estimate the settlement below Geopier Rammed Aggregate Pier - supported footings rely on the performance and interpretation of a modulus test conducted on a single Rammed Aggregate Pier element. The test is used to determine the spring stiffness of a single element. However, actual footings are generally supported by multiple elements and the interaction effects between ...
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4.3 Modulus Test: The purpose of the modulus test is to examine the applied stress versus deflection behavior of a representative Rammed Aggregate Pier . If there are only a limited number of Rammed Aggregate Piers needed on a project, a modulus test may not be performed.
of the aggregate is verified at the site with flow tests, the performance is verified with the modulus test and the Designer approves the type and gradation of the
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It is important that a structural engineer understand the installation and testing procedures of rammed aggregate piers as well as their load transfer mechanism and failure modes before selecting RAPs as a method of ground improvement.
IMPACT The Geopier impact® system creates Rammed aggregate pier ® (Rap) elements using a patented vertical ramming process. The Geopier impact system uses a patented displacement mandrel to reinforce good to poor soils, including loose sand, soft silt and clay, mixed soil layers, uncontrolled fill, contaminated soils and soils below the groundwater table. The displacement process allows for ...
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1.5.6. Identification of cave-in contamination. 1.5.7. The modulus test. 1.5.8. The bottom stabilization test for Geopier replacement elements. 1.5.9. The crowd stabilization test for Geopier displacement elements. 1.5.10 Intimate contact between the CAP element and the foundation bottom. 2. The required qualifications of the special inspector.
A Geopier load test, or modulus test, is performed on single test pier typically constructed in the "worst" area of the site (i.e. area containing the softest soil conditions). Furthermore, modulus tests are conducted to a pressure equal to at least 150% of the maximum design top of pier stress to assure a reasonable level of safety that supports long term settlement control and demonstrates ...
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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% ...
The Stone Column or Aggregate Pier system shall be designed to preclude plastic bulging deformations at the top-of- pier design stress and to preclude significant tip stresses as determined from the shape of the telltale test curve from telltales installed in modulus test piers .