Typical geomechanical problems associated with railroads on shrink-swell soils

• Railroad on shrink-swell soils: some typsswical geomechanical problems and possible solutions.
• Effect of environmental actions on railway subgrade and embankment and their impact on railroad performance.
• Test site to study the behavior of railtracks on expansive clays.
• Numerical coupled hydro-mechanical modelling of a railroad section on shrink-swell soils.

Problems associated with continuous settlement are typically observed in railroads in Texas. Different physical mechanisms can be behind these issues. Natural soils in Texas are dominated by shrink-swell clays (also known as expansive soils). These kinds of clays are characterized by significant expansions and contractions when they are subjected to wetting and drying processes, respectively. Railways on shrink-swell soils are subjected to huge solicitations associated with the volume changes of the soil, generally leading to unacceptable uneven settlements. Relative movements of railroads constructed on this type of soil can also be related to progressive shear failure, and long term consolidation and creep. Uneven settlements affect both: operational costs and safety. The mechanisms behind the observed railroads problems on shrink-swell soils, and the associated (possible) remedial solutions, are still unclear. A site in Texas has been recently selected to study in detail the aforementioned problems. The case study consists of three different sections: a fill, a cut, and a reference section. In this paper we discuss the typical geomechanical problems associated with railroads in Texas, Some possible remedial solutions for those problems are discussed as well. We also present the test site selected to study this problem under actual conditions and at full scale. Numerical analyses involving a typical railroad section are presented and discussed in this paper as well.