Rock-Socketed Shafts for Highway Structure Foundations







PREFACE

During the past 25 years, much knowledge and experience has been acquired by the engineering

and construction industries on the use of rock-socketed shafts for support of transportation

structures. This synthesis collected, reviewed, and organized the most salient

aspects

of this knowledge and experience to present it in a form useful to foundation designers,

researchers, contractors, and transportation officials. The objectives of this report were

to collect and summarize information on current practices pertaining to each step of the

design process, along with the limitations; identify emerging and promising technologies;

determine the principal challenges in advancing the state of the practice; and provide

suggestions for future developments and improvements in the use and design of rock-socketed

shafts.


For this TRB synthesis report a literature review was conducted on all topics related to

drilled shaft in rock or intermediate geomaterials. A questionnaire was developed and distributed

to the principal geotechnical and structural engineers of U.S. state and Canadian provincial

transportation agencies. Questions were grouped into the following categories: use

of rock-socketed shafts by the agency, evaluation of rock and intermediate geomaterials,

design methods for axial loading, design methods for lateral loading, structural design,

construction, and field load and integrity testing.

John Turner, Professor of Civil and Architectural Engineering, University of Wyoming,

Laramie, collected and synthesized the information and wrote the report, under the guidance

of a panel of experts in the subject area. The members of the topic panel are acknowledged

on the preceding page. This synthesis is an immediately useful document that records the

practices that were acceptable within the limitations of the knowledge available at the time

of its preparation. As progress in research and practice continues, new knowledge will

be added to that now at hand.


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