01128906

Monograph

With increased urbanization, selection of deep foundations (bridges, signage, walls, etc.) is being controlled by the minimization of impact or disturbance, as well as quality assurance and control (e.g., proof testing, etc.). Deep foundations have thus migrated from driven piles to drilled shafts to tip grouted drilled shafts. Recently, a number of European and Asian designers/contractors have begun grouting driven precast concrete piles along their sides and at their tips. The use of these in Florida soils as well as their design is the focus of this research. Testing of the proposed jet grouted piles revealed problems with both the grout delivery system, as well as the grout mix design. In addition, full scale tests showed greater radial than vertical grout movement as well as poor bonding between the grout and precast member. Subsequently, improvements to the grout delivery system, mix design and incorporation of a semi-rigid high tensile strength membrane were introduced. Testing on jet grouted piles from 8 to 20 feet in length revealed both excellent grout side grout coverage, as well as unit side resistance under both axial and torsional loading. Using cavity expansion theory and/or in situ Pressuremeter testing, both the grout pressures and skin and tip resistances may be estimated. The new pile has a number of attractive features: 1) known structural cross-section; 2) minimal installation disturbance; and 3) proof testing and higher LRFD theta factors for design.

BD-545 #31

English

158p

2009-3

Final Report

9/22/04-2/28/09

Print

Figures; References; Tables

Pile driving; Pile foundations; Prestressed concrete

Deep foundations; Grouted driven piles; Jet grouting; Pressure grouting

Construction; Highways; I53: Construction of Bridges and Retaining Walls

TRIS

May 19 2009 7:49AM