Browsing by Autor "Mario Terceros Arce"

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Increased Axial Resistance of Small-Diameter Piles and Ground Anchors by Using Expander Bodies
(2021) Antonio Marinucci; Mario Terceros Arce; Mario A. Terceros Herrera
An expander body (EB) is an element consisting of a folded steel sheet with a circular cross section that can be added to a relatively small diameter pile and ground anchor to increase axial resistance. During the injection of pressurized grout, the outer portion of the EB is expanded (inflated) from its original diameter of about 120 mm (4.75 in.) to about 400–800 mm (15.75–31.5 in.), depending on the model and stiffness of the in situ soil surrounding the device. Due to the controlled expansion process, the stress state is improved around the device and can be deduced from the recorded measurements; hence, the available axial resistance for these smaller diameter elements can be increased considerably due to the greater soil stiffness and shear strength around the device as well as to the larger cross-sectional area (i.e., end resistance) and larger surface area. This paper describes the general principles of the EB system as well as the construction, grouting operation, quality control, and select results from static axial compression load tests performed on continuous flight auger (CFA) + EB piles.
The Use of an Expander Body with Full Displacement Piles in Medium-Dense Sandy Soils
(2016) Mario Terceros Arce; Mario A. Terceros Herrera
The expander body (EB) technology has been used successfully to increase the pile toe capacity of bored piles in loose to medium dense soil. An important advantage of the EB system is the ability to monitor the EB expansion process, which provides important information regarding soil strength and soil stiffness. This information, obtained for each installed pile, can be used to determine the actual shape and pile toe area. The expansion pressure can be used to design the pile base capacity. The expander body system has been recently improved by incorporating the possibility of post-grouting of the soil below the expanded pile toe. This improvement measure provides additional strength and stiffness to the pile toe and reduces pile settlement. Using a soil displacement auger, which avoids soil decompression and increases lateral soil stress, the shaft bearing capacity can increase, mainly in comparison with the traditional bored piles under bentonite. This paper describes the principle of the EB system and its combination with the full displacement system for the shaft. A high degree of quality control can be achieved by monitoring the entire pile installation process, including the displacement pile and the expander body.
Tip Post-Grouting Using Smart Cells of 126 Drilled Shafts at Two Bridges in Bolivia
(2021) Antonio Marinucci; Mario A. Terceros Herrera; Mario Terceros Arce
A smart cell is a closed-type grout distribution system that is attached to the bottom of a reinforcement cage for drilled shaft foundations and acts in a similar manner to a hydraulic jack in bi-directional static load testing. Control of the grout is maintained during grouting, and a uniform stress is imparted across entire base area simultaneously. The goals of tip post-grouting are to improve the stiffness of the in situ soil, improve the shaft’s nominal axial resistance, and better align the load transfer curves to the project requirements. This paper will present an overview, basic principles, and the design methodology of tip post-grouting using this technique. The construction, tip post-grouting, select results, and general observations from the grouting performed on more than 120 total drilled shafts for Las Marotas vehicular bridge crossing the Paraí River and the Yapacani railway bridge structure crossing the Yapacani River, Bolivia, will also be presented and discussed. The general subsurface conditions for the sedimentary deposits at the two bridge sites consist of highly variable soil deposits, bedding, composition, and engineering characteristics. The diameter of the temporarily cased drilled shafts was either 1,200 mm (4 ft) or 1,500 mm (5 ft), and the length ranged from nearly 15 m (49 ft) to nearly 25 m (82 ft). Most of the drilled shaft foundations for these bridge structures were installed with a post-grouting cell at the bottom of its reinforcement cage to enhance performance and to reduce uncertainty. Using the measurements of the grouting operation, the premobilization of axial resistance and induced load imparted into the drilled shaft and to the soil beneath the base will be discussed.