Development of a New Asymmetric Anchor Plate for Prefabricated Vertical Drain Installation via Centrifuge Model Tests

Abstract

This study investigates the kinematic behavior of a clay-mandrel-anchor system during the driving-retrieval process and its influence on the installation of prefabricated vertical drains and clay disturbance. In addition, a new anchor plate with an asymmetric shape is proposed as an alternative for improved anchoring performance and clay disturbance mitigation. To investigate the behavior of the clay-mandrel-anchor system, two-dimensional centrifuge model tests were developed and successfully performed to visualize anchoring kinematics and deformation of the clay layer. The tests demonstrated that the asymmetric anchor plate effectively provides an anchoring mechanism and reduces the degree of disturbance. The conventional anchor has potential risk of delayed anchoring and thus unsuccessful installation. While the amount and extent of clay deformation are obviously affected by the protruding length of the anchor plates into the clay, the protrusion length has less influence on the range of the smear zone than the degree of disturbance in the smear zone. The asymmetric anchor considerably reduces the smear effect, as three sides of the mandrel have minimal protrusion length from the center unlike in the conventional anchors. (C) 2013 American Society of Civil Engineers.