Reinforcement and mud-pumping benefits of geosynthetics in railway tracks: Model tests

Chawla, Sowmiya; Shahu, J. T.

doi:10.1016/j.geotexmem.2016.01.005

Cited by 63 publications

(22 citation statements)

References 14 publications

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“…of the back-saturated specimen prior to applying the cyclic loading (see Table 2). The above observations are further supported by large-scale testing conducted by Chawla and Shahu (2016), where mud pumping under railway loading was simulated using physical modelling of a track element, and a substantial increase in the water content was measured just beneath the sleeper after instability.…”

Section: Fluidization Of Subgrade Soil Due To Cyclic Loadmentioning

confidence: 57%

“…Data presented in Fig. 3 shows that mud pumping incidents are identified mostly for fine grained soils having a low to moderate plasticity index (i.e., PI < 26) (Ayres 1986;Raymond 1986;Alobaidi and Hoare 1996;Muramoto et al 2006;Liu et al 2013;Duong et al 2014;Chawla and Shahu 2016).…”

Section: Experimental Investigation 21 Soil Propertiesmentioning

confidence: 99%

“…For example, Takatoshi (1997) attributed this to the suction at the base of sleeper (tie) induced by the difference in stiffness between ballast and sleeper, and the imperfect contact at their interface to explain the migration of fines to the surface. On the other hand, subsequent studies (Alobaidi and Hoare 1996;Muramoto et al 2006;Duong et al 2014;Chawla and Shahu 2016) proposed the existence of an apparent relationship between the rising EPP and the vulnerability of fines for infiltrating the upper granular layers. The process of fluidized fines transported upwards from the soil (subgrade) often results in the fouling of overlying ballast causing a reduction in the inter-particle friction (shear strength) and impeding the drainage capacity (permeability) of the granular assembly (Selig and Waters 1994;Ionescu 2004; Tennakoon and Indraratna 2014).…”

Section: Introductionmentioning

confidence: 99%

“…Although this approach could simulate mud pumping in the laboratory, the rigid cell boundary cannot regulate the confining pressure in the subgrade. A few studies (Ghataora et al 2006;Duong et al 2014;Chawla and Shahu 2016) have also applied a certain 'free drainage' condition at the simulated subgrade surface. However, in reality, the fouling and degradation of the substructure materials may impede the free draining capability of the ballast.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory study on subgrade fluidization under undrained cyclic triaxial loading

et al. 2020

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A long term issue that has hampered the efficient operation of heavy haul tracks is the migration of fluidized fines from the shallow soft subgrade to the overlying ballast, i.e., mud pumping. This paper presents a series of undrained cyclic triaxial tests, where realistic cyclic loading conditions were simulated at low confining pressure that is typical of shallow subgrade beneath a ballast track. Subgrade soil specimens with a low plasticity index collected from a field site with recent history of mud pumping were tested at frequencies from 1.0 to 5.0 Hz and a cyclic stress ratio (CSR) from 0.1 to 1.0. The experimental results indicate that under adverse loading conditions of critical cyclic stress ratio (CSRc) and frequency, there is upward migration of moisture and the finest particles towards the specimen top, and this causes the uppermost part of the soil specimen to soften and fluidize. Conversely, a smaller value of CSR tends to maintain stability of the specimen despite the increasing number of loading cycles. It is noteworthy that for any given combination of CSR and frequency, the relative compaction has a significant influence on the cyclic behaviour of the soil and its potential for fluidization.

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Section: Fluidization Of Subgrade Soil Due To Cyclic Loadmentioning

confidence: 57%

Section: Experimental Investigation 21 Soil Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laboratory study on subgrade fluidization under undrained cyclic triaxial loading

et al. 2020

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“…The relatively old existing rail infrastructure, together with the continuous increase in freight tonnage, have triggered various geotechnical problems in existing railroads involving both, subgrade and embankment. Geotechnical problems associated with railroads are related (but not limited) to (a) mud pumping (eg,); (b) subgrade subsidence (eg,); (c) progressive shear failure (eg,); (d) ballast pocket (eg,); (e) massive shear failure (eg,); (f) subgrade cavities and collapse (eg,); (g) shrink‐swell soils (eg,); and (h) frozen soils (eg,). Railroads issues associated with shrink/swell soils are discussed in detail in Sanchez et al…”

Section: Introductionmentioning

confidence: 99%

Numerical study on the effect of rigid inclusions on existing railroads

Wang

Sánchez

Briaud

2019

Num Anal Meth Geomechanics

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Summary Railroad track problems have been exacerbated by the continuous increase in freight loads and train traffic. The need to implement soil improvement technique in a relatively short window‐time (ie, to minimize train‐traffic disruption) is a key aspect to be considered when adopting a convenient remedial solution to control settlements in railroads constructed on problematic subgrades. Rigid inclusions are selected in this paper because they are reliable solutions relatively easy to implement. Furthermore, they can be used in different ground conditions and are suitable for short construction times (eg, do not require a curing time, as in grouting methods). Typical (analytical) methods for the design of rigid inclusions are adopted in this paper to define an optimal distribution of piles for the case of existing railroads. The selected layout is then analyzed in detail by means of a 3‐D dynamic finite element simulator using both, elastoplastic and elastic models. The performance of rigid inclusions is studied considering different operational scenarios, with dynamic and static loads, as well as involving subgrades with different plasticity index values. It is found that the predictions from the analytical design methods for rigid inclusion tend to be unconservative when compared against the finite element results. As for the numerical solutions, the most unfavorable stress condition is associated with the dynamic elastoplastic finite element solution. It is estimated that the rigid inclusions will contribute to a reduction in the ground settlements of around 15% to 20%, depending on the subgrade plasticity index.

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