Practical Advice for Foundation Design – Micropiles for Structural Support

Bruce, Donald A.; Cadden, Allen; Sabatini, Paul J.

doi:10.1061/40777(156)14

Cited by 15 publications

(6 citation statements)

References 3 publications

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“…As shown in Fig. 2, the center-to-center spacing between the WMP and each Type A MP was more than 3D, which is a prevalent MP spacing (Bruce et al, 2005;Abdlrahem and El Naggar, 2020;FHWA, 2005). The loading test setup included a reaction beam, two tension anchors acting as reaction supports, a hydraulic jack, and two displacement gauges.…”

Section: Test Setup Methods and Instrumentationmentioning

confidence: 89%

A field study on the load sharing behavior of a micropiled raft underpinned by a waveform micropile

2022

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A waveform microiple(WMP) uses jet grouting method to generate shear keys along the pile shaft for improving the shaft resistance and cost efficiency. In this study,field loading tests were performed in this study to characterize the load sharing behavior upon inclusion of a waveform micropile (WMP) in a group of four micropiled-raft. First, single-pile compressive loading tests were conducted on three WMPs and five Type A micropiles (MP). Subsequently, a group-pile loading test was performed on a piled raft comprising 2 × 2 MPs and a central WMP. The load–settlements, axial stiffnesses, and load transfer mechanisms of individual MPs were analyzed during the tests, including the short- and long-term effects of the axial stiffnesses of the MPs on the load sharing ratio of the micropiled-raft. The single-pile loading test results revealed that the shear keys along the WMPs caused its bearing capacities and axial stiffnesses to be 1.5 times and 2–5 times higher than those of MPs, respectively. In the micropiled-raft loading test, the load sharing ratios of the MPs increased with their axial stiffnesses, and the highest load sharing capacity was exhibited by the WMP, which constituted 30% of the total load and 2–3 times that of MPs. Moreover, the influence of raft on the load-sharing capacity should be considered as well.

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Section: Test Setup Methods and Instrumentationmentioning

confidence: 89%

A field study on the load sharing behavior of a micropiled raft underpinned by a waveform micropile

2022

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“…Se establecieron algunos parámetros para las pruebas de carga [11], determinando que se pueden ejecutar con cargas de hasta dos veces la carga de diseño, siempre y cuando no se exceda el 80 % de la capacidad estructural final. Para el caso de pilotes dañados, las cargas de compresión son compartidas entre la fundación existente y los micropilotes, mientras que las cargas de tensión, laterales y de momento son soportadas únicamente por los micropilotes.…”

Section: Capacidad De Cargaunclassified

“…La capacidad de carga final bajo tensión corresponde al 60 % aproximadamente de la capacidad final de aquellos bajo compresión. Basado en lo anterior y de acuerdo con lo mencionado por [11], la fundación objeto de estudio presentaba un daño leve.…”

Section: Capacidad De Cargaunclassified

Inclusión de micropilotes como elementos recuperadores de carga en cimentaciones: revisión del estado del conocimiento

Guerrero

Rincón

2022

Ing.

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Contexto: Los micropilotes son utilizados como elementos de refuerzo del suelo o de recalce, dicha función es comprobada y analizada por diferentes autores. En Colombia el uso de esta técnica está limitado a conceptos propios del geotecnista que involucran conocimientos empíricos y experiencias exitosas. En consecuencia, es necesaria la compilación de variables clave y metodologías analíticas y numéricas para la mejor comprensión de esta técnica. Método: En este documento se presenta un estado del arte sustentado en artículos e investigaciones que tienen como objeto el análisis y la evaluación del comportamiento de los micropilotes como elementos recuperadores de capacidad de carga en grupos de pilotes que presentan defectos. Resultados: Los hallazgos identificados en los documentos consultados logran ser sintetizados como un soporte teórico que se convierte en un punto de partida para futuras investigaciones en este campo de la ingeniería geotécnica. Conclusiones: Se logra evidenciar que los micropilotes tienen una influencia positiva en la recuperación de carga de fundaciones existentes, demostrando la importancia de efectuar ensayos y análisis de campo directamente en Colombia, considerando los estratos de suelos específicos que se encuentran en el país.

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“…The CMFF design approach consists of 2 phases: Phase 1: In the first phase, the feasibility of utilizing micropiles in the karstic terrain, as well as design the micropile itself satisfying geotechnical and structural safety. The steps taken in this design phase follow the seven design steps summarized recently by Bruce, D.A. et al (2005).…”

Section: Cmff Theoretical Approachmentioning

confidence: 99%

Micropiling in Karstic Rock: New CMFF Foundation Solution Applied at the Sanita Factory

Ballouz¹

2005

Sinkholes and the Engineering and Environmental Impacts of Karst

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The new Sanita factory is a 2 story factory warehouse covering an area of 10,000 m 2 located in Zouk-Mosbeh, Lebanon. The warehouse is composed of 140 reinforced concrete columns supporting a one way pre-stressed concrete slab designed to carry 25 kN/m 2 of industrial live load plus a future steel structure. The soil substratum consists of 1 to 4 m of silt on top of the bedrock. The bedrock is hard karstic limestone with cavities and fissures. Because of the karstic nature of the rock, the original design called for a strip foundation on top of the rock with a maximum allowable bearing pressure of 400 kPa. Combined Micropiles and Footing Foundation, CMFF, is a new foundation system that was created by the International Institute for Geotechnics and Materials, iIGM, and implemented as an alternative solution for this particular project. This new system was designed utilizing a finite element model. There were two major concerns regarding this solution. The first concern was with respect to the loadsettlement performance of the micropile in the karstic terrain. The second concern was to prove the advantages of the CMFF system considering the particular conditions of the project. Two static load tests were performed on the micropiles with different methods. The results of the tests permitted modeling the soil/structure interactive foundation system. CMFF in karst offered many technical advantages over classical methods. A cost saving of about 40% was also accomplished in the foundation system without compromising safety. This paper summarizes the results of the load tests and the advantages of CMFF in this particular project. The paper also presents the different phases of the foundation system by covering the design details, construction aspects, performance evaluation, and cost analysis.

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Practical Advice for Foundation Design – Micropiles for Structural Support

Cited by 15 publications

References 3 publications

A field study on the load sharing behavior of a micropiled raft underpinned by a waveform micropile

A field study on the load sharing behavior of a micropiled raft underpinned by a waveform micropile

Inclusión de micropilotes como elementos recuperadores de carga en cimentaciones: revisión del estado del conocimiento

Micropiling in Karstic Rock: New CMFF Foundation Solution Applied at the Sanita Factory

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