Deformation characteristics of fine-grained soil under cyclic loading with intermittence
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REVIEW PAPER
Deformation characteristics of fine-grained soil under cyclic loading with intermittence RuSong Nie1,2 • YaFeng Li1 • WuMing Leng1,2 • HuiHao Mei1 • JunLi Dong1 • XiXi Chen1 Received: 27 June 2019 / Accepted: 10 March 2020 Ó Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Since there is an interval time between two trains traveling in the same direction on an automatically blocked line, the dynamic loading on the railway subgrade is composed of periodic vibration when the train passes and an intermittent stage after a train has passed. Take into account this characteristic, a series of continuous-stopping repeated load triaxial tests were conducted to study deformation characteristics such as plastic strain and elastic strain of fine-grained soil under intermittent loading. Compared to continuous loading, it is found that the intermittent stage has a significant effect on the deformation characteristics of subgrade. The excess pore water pressure accumulated during the loading stage dissipated during the intermittent stage. The development of plastic strain in subsequent loading stages slowed down significantly, and the axial strain of the sample rebounded in the intermittent stage, so cumulative plastic strain was reduced. The intermittent effect on reducing elastic strain was, however, limited. An increase in intermittent time can also improve the resistance of the sample to subsequent cyclic loading. An alternating continuous-stopping loading mode can better simulate intermittent loading of trains in actual train operation and produce more practical results, providing a theoretical basis and guidance for further understanding of deformation characteristics of railway subgrade. Keywords Deformation characteristics Excess pore water pressure Fine-grained soil Intermittent loading of trains Repeated load triaxial test List of qs qdmax wopt wsat k20 wL wp Ip10 K r3 rs rd
symbols Particle density Maximum dry density Optimum moisture content Saturated moisture content Permeability coefficient Liquid limit Plastic limit Plastic index Compaction coefficient Confining pressure Static deviatoric stress Dynamic stress amplitude
& YaFeng Li [email protected] 1
Department of Geotechnical Engineering, School of Civil Engineering, Central South University, No. 68, Shaoshan South Road, Changsha 410075, Hunan, China
2
MOE Key Laboratory of Engineering Structures of Heavyhaul Railway, Central South University, Changsha 410075, Hunan, China
ep ee t N
Accumulated plastic strain Resilient strain Loading time Number of cycles
1 Introduction As the substructure of a railway, subgrade is a fundamental component of the entire railway transportation system. The dynamic characteristics of subgrade filler, i.e., dynamic strength, permanent deformation, and elastic deformation, directly determine the critical dynamic stress, the cumulative settlement, and the elastic deformation of subgrade and ultimately affect the design, operation, and mai
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