Granular sub-ballast compaction control methods in high‐speed railway lines. Spanish experience

Abstract

Abstract In recent years, the Spanish Geotechnical Laboratory of CEDEX (Centro de Estudios y Experimentacion de Obras Publicas) has developed a series of geotechnical studies and monitoring techniques for ADIF (the Spanish Railway Infrastructure Administrator). Within this framework, this paper describes the work carried out by CEDEX, testing several sections to compare different control equipment, in order to study new methods of control of the degree of compaction and deformation modulus of the sub-ballast that may become alternatives to the static load plate test, currently included in the specifications of ADIF. The equipment and techniques included in the testing campaigns are: static load test (300 and 600 mm), nuclear method contrasted with sand-cone test for the determination of density and water content, portancemetre, dynamic load test with 300-mm plate (HMP light test equipment), and dynamic load test with 600-mm plate (Dynaplaque). Thus, the suitability of the sub-ballast compaction control tests currently included in the specifications of ADIF has been evaluated. Except for the density determination tests, the results obtained show a time evolution of the parameters registered. This study allows drafting a proposal of prescriptions for the control of the sub-ballast compaction with high-performance dynamic equipment. Future research lines aim to study the observed phenomena. The results point out the need to experiment in other railway sections so as to confirm and generalize the conclusions of this study.