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    Volume 41, Issue 1 (January 2018)

    Shallow-Layer p-y Relationships for Micropiles Embedded in Saturated Medium Dense Sand Using Quasi-Static Test

    (Received 9 November 2016; accepted 24 May 2017)

    Published Online: 2017

    CODEN: GTJODJ

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    Abstract

    Micropiles are being increasingly used in existing structures for foundation rehabilitation and in new structures to enhance their seismic safety. For the seismic design of piles in sands, numerical models of piles under lateral loading using the p-y relationships proposed by the American Petroleum Institute (API) are widely used. However, the validity of this approach has been questioned by many researchers. In this regard, this study presents the development of experimental and numerical p-y relationships for shallow layers (depths less than 1.0 m) of micropiles in fully saturated medium-dense sands using a quasi-static test. A steel pipe was embedded into the sands and fixed at the bottom of the soil container. Lateral loads were applied on the pile head using the displacement-control technique. A piecewise-function–based p-y derivation method was adopted to develop the experimental p-y curves. Distributions of bending moment, shear force, soil reaction, rotation, and deflection along the pile are presented. Subsequently, bilinear shallow-layer p-y relationships are proposed. Test results show that experimental p-y curves for micropiles at the shallow depths are more flexible (lower initial stiffness) and stronger (greater strength) than those recommended by the API. The quasi-static test is then simulated using either the proposed bilinear p-y relationships or those recommended by the API. Results show that the global force-displacement relationship, bending moment distribution and lateral deflection of piles are accurately predicted by the proposed shallow-layer p-y relationships. By contrast, the conventional API p-y relationship reasonably predicts the lateral strength and maximum bending moment while overly predicting the depth-to-maximum bending moment of micropiles in saturated medium-dense sands.

    Author Information:

    Wang, Xiaowei
    State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai

    Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH

    Ye, Aijun
    State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai

    Shafieezadeh, Abdollah
    Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, Columbus, OH

    Li, Jianzhong
    State Key Laboratory of Disaster Reduction in Civil Engineering, Tongji University, Shanghai


    Stock #: GTJ20160289

    ISSN:0149-6115

    DOI: 10.1520/GTJ20160289

    Author
    Title Shallow-Layer p-y Relationships for Micropiles Embedded in Saturated Medium Dense Sand Using Quasi-Static Test
    Symposium ,
    Committee D18