Design Loading for Deeply Buried Box Culverts







Design Loading for Deeply Buried Box Culverts

Kyungsik Kim

and

Chai H. Yoo

Highway Research Center Auburn University

Auburn University, Alabama

May 2002



Acknowledgments

The investigation which led to the results presented herein was supported jointly by the Huff Eminent Scholar fund and the Highway Research Center at Auburn University. The authors gratefully acknowledge the assistance provided by D. L. Allen of Kentucky Transportation Research Center including the source code of PC version ISBILD.

Disclaimer

The opinions and conclusions expressed or implied in the report are those of the authors. They are not necessarily those of the funding agencies.



1.1 Statement of the Problem



INTRODUCTION

Cast-in-place or precast reinforced concrete box culverts are widely used throughout the

world to provide safe and relatively economical structures for the conveyance of water, vehicles,

utilities or pedestrians. Although the single cell or multi-cell box culverts are rather simple

structures, the loadings applied to these structures during their construction and subsequent

service life can be complex. These structures are subjected to substantial vertical and lateral

earth pressures, and are often SUbjected to significant temporary loadings during the construction

of the embankment. In spite of the complex nature of the loading around these structures, simple

routine design procedures would be highly desirable if they could be made possible.

When the relative settlement of the soil prism directly above the structure is greater than

that of the adjacent soil prisms, as in trench installations, the layers of soil in the central prism

are subjected to a reverse arch shape defonnation and consequently the earth pressure on the

structure is reduced by the amount of the shearing forces exerted to the central soil prism.

Likewise, when the relative settlement of the soil prism directly above the structure is less than

that of the adjacent soil prisms, as is usually found in embankment installations, the layers of soil

on the central prism are subjected to an arch shape defonnation and the earth pressure on the

structure is increased. Although Marston[I,2] and Spangler[3,31,32] successfully quantified these

phenomena by solving differential equations based on the equilibrium conditions of a simplified

free body of prisms, an opportunity exists to revisit the problem using the modern-day numerical

techniques made possible by the development of finite element methods.



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