Using a modified direct shear apparatus to explore gap and size effects on shear resistance of coarse-grained soil

Fu, Wei; Zheng, Xing; Xiao-zhang, Lei; Deng, Jiang

doi:10.1016/j.partic.2014.11.013

Cited by 12 publications

(5 citation statements)

References 29 publications

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“…Under the same normal stress, the peak shear stress for the mixture G3 decreases as the opening width increases [27,28]. For example, for a normal stress of 100 kPa, the peak shear stresses are 267.6, 146.3, 140.0, 129.0, 119.3, and 96.8 kPa for opening sizes of 5, 10, 15, 20, 25, and 30 mm, respectively.…”

Section: Plate Opening For G3mentioning

confidence: 98%

Direct Shear Test on Coarse Gap‐Graded Fill: Plate Opening Size and Its Effect on Measured Shear Strength

Cai

Wei

Xiao

et al. 2020

Advances in Civil Engineering

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In this paper, three different rock-soil mixtures were reconstituted in laboratory, which were designed to mimic the proportions of coarse and fine particles in the high fill used at the airport construction sites. The shear strength of the reconstituted mixtures was determined by both large-scale direct shear tests (DSTs) with different plate opening sizes and triaxial compression tests. By comparing the test results, the most appropriate plate opening size for DSTs on coarse gap-graded rock-soil mixtures is discussed. The test results indicate that the opening size has a significant effect on the measured shear strength of gap-graded rock-soil mixtures. For DSTs under the same normal stress, the peak strength decreases with increasing plate opening size. For the gap-graded mixture with a small proportion of coarse particles, a plate opening size of one-third to one-quarter of the maximum particle size (dmax) is suitable. With a higher coarse particle content, the opening size should be increased appropriately. If the percentage of gravels (5.0 mm < d < 20.0 mm) is more than 47%, a plate opening size of slightly greater or less than one-half dmax is more appropriate.

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Section: Plate Opening For G3mentioning

confidence: 98%

Direct Shear Test on Coarse Gap‐Graded Fill: Plate Opening Size and Its Effect on Measured Shear Strength

Cai

Wei

Xiao

et al. 2020

Advances in Civil Engineering

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“…By this way, following the test procedure with a shear gap can be accomplished. e suggested shear gaps for the test of coarse-grained soils are not coherent [20,21,27], meaning that more work from an experimental or numerical aspect to discuss relation between grain size and gap effect is rather needed. In order to present the gap effect on the strength reduction properties of S-RM, the shear gaps were arranged from 0 mm to 8 mm with an increment amplitude of 2 mm in this work as the largest particle size is 10 mm.…”

Section: Arranging Shear Gaps and Related Parametersmentioning

confidence: 99%

“…However, according to the author's knowledge, only few articles about shear gap effect on shear strength of coarsegrained materials have been published [20]. Shibuya et al [21] pointed out that the space between the upper box and lower box should be maintained at a constant value slightly larger than the thickness of a free shear band (approximately 10-20 times D50 for the sands).…”

Section: Introductionmentioning

confidence: 99%

A Systematic Method to Evaluate the Shear Properties of Soil-Rock Mixture considering the Rock Size Effect

Ren

Guo-fan

Qiu

et al. 2018

Advances in Civil Engineering

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The soil-rock mixture (S-RM) is widely applied in the geotechnical engineering due to its better mechanical properties. The shear strength, an essential aspect of S-RM which governs the stability and the deformation, is rather necessary to be revealed properly. The extraordinary issue of S-RM compared to fine-grained soils is the grain size effect on the strength analysis. This paper proposes a systematic method to obtain the realistic shear strength of S-RM by detecting the rock size effect. Firstly, based on fractal theory, the rock size was determined as 5 mm by the multifractal property of granular size distribution. Then, based on 2 selected specimen sizes combining the engineering dimension, shear gaps (T) effect and specimen size effect on the shear strength of S-RM have been investigated. It is shown that the gap of the direct shear test decides the physical mechanism of particles forming the shear resistance of S-RM based on the variation of apparent cohesion and mobilized internal friction angle. Specimen size effect is weakened by the gap effect considering the boundary effect. Realistic and stable shear strength parameters of S-RM have been researched by a reasonable gap (0.2–0.4D, where D is the largest particle size).

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“…They are usually due to the infiltration of rainfall, which reduces the shear strength of the slope soil and eventually causes the slope to fail [2][3][4]. Heavy rainfall for a short time or moderate rainfall for a long time can lead to a large number of landslides, most of which occur in shallow locations above ground level [5]. According to statistics, VS accounted for 38% of the 133 shallow landslides in northern Switzerland since 2015 [6].…”

Section: Introductionmentioning

confidence: 99%

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

2021

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Although vegetation is increasingly used to mitigate landslide risks, how vegetation roots affect the landslide threshold of slope has rarely been explored, particularly in the case of lateral runoff. In this study, we established a two-dimensional saturated-unsaturated infiltration equation considering the hydraulic effects of vegetation roots. The analytical solution for the shallow unsaturated two-dimensional coupled infiltration of vegetated slope (VS) was obtained by a Fourier transform technique. The numerical method was used to evaluate the stability of VS caused by four root architectures, the rainfall amount, and the rainfall duration. Subsequently, the transformation law in runoff, vegetation evaporation, and landslide threshold was analyzed. The results indicate that the factor of safety (FOS) increases with increasing drying time and decreases with increasing depth; the minimum FOS is at the junction of the root-rootless zone. Runoff and vegetation evaporation are favorable for the shallow stability of VS. The time of the safe area is 35 h for rainfall amount 500 m in the uniformly root clay slope. Moreover, four landslide threshold curves that reflected the root architecture, rainfall amount, and rainfall duration are developed, which are more realistic than those created using one-dimensional instability modeling.

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Using a modified direct shear apparatus to explore gap and size effects on shear resistance of coarse-grained soil

Cited by 12 publications

References 29 publications

Direct Shear Test on Coarse Gap‐Graded Fill: Plate Opening Size and Its Effect on Measured Shear Strength

Direct Shear Test on Coarse Gap‐Graded Fill: Plate Opening Size and Its Effect on Measured Shear Strength

A Systematic Method to Evaluate the Shear Properties of Soil-Rock Mixture considering the Rock Size Effect

Effect of Vegetation Roots on the Threshold of Slope Instability Induced by Rainfall and Runoff

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