Effects of initial particle gradation and rock content on crushing behaviors of weathered phyllite fills – A case of eastern Ankang section of Shiyan–Tianshui highway, China

Liu, Feifei; Mao, Xuesong; Fan, Yushuo; Wu, Ling-Ling; Liu, Wei Victor

doi:10.1016/j.jrmge.2019.07.011

Cited by 14 publications

(4 citation statements)

References 46 publications

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“…The aforementioned researches are all focused on the behaviour of S-RMs containing stiff rock blocks, called as "stiff S-RMs", characterized by blocks difficult to be broken during shearing. However, S-RMs with soft rock blocks, referred to as "soft S-RMs" in this paper, also exist and were found in landslides and artificial fills (Roadifer and Forrest 2012;Kahraman et al 2015;Liu et al 2020;Zhang et al 2020;Xu and Zhang 2021). In this case, the soft blocks can easily break during shearing processes, implying a shear behaviour is completely different from that of the stiff S-RMs.…”

Section: Introductionmentioning

confidence: 88%

Influence of Block form on the Shear Behaviour of Soft Soil–Rock Mixtures by 3D Block Modelling Approaches

et al. 2022

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The influence of block forms on the shear behaviour of soil–rock mixtures with soft blocks (soft S–RMs) can be efficiently investigated by the discrete element method (DEM) on the basis of accurate 3D models accounting for the block breakage. This paper proposes a novel modelling approach, based on the spherical harmonics series, for the generation of 3D block geometries with different forms but same convexity and angularity. An already existing non-overlapping modelling approach was improved, characterized by a reduced computational cost, for the set-up of 3D block DEM models accounting for the block breakage. A number of soft S–RM DEM samples, subjected to numerical direct shear tests, were generated to analyze the influence of block forms and volumetric block proportion VBP on the mesoscopic and macroscopic behaviours. The results showed that the breakage degree is maximum for the spheroidal blocks, followed by the oblate, prolate and blade ones, due to the combined influence of the block frictional sliding and rotation. The shear strength of soft S–RMs is mainly controlled by the block interlocking and breakage, being maximum in the case of spheroidal block samples when the applied normal stress is low and in the case of prolate and blade ones for a high normal stress. It was found that a nonlinear Mohr–Coulomb criterion can provide a good description of the shear strength envelope of soft S–RMs. Soft S–RMs are characterized by a higher friction angle if composed by spheroidal and prolate blocks when the VBP is 40%, due to their elevated block interlocking, and in the case of prolate and blade blocks when the VBP is 60% at the higher normal stress, due to their lower block breakage degree.

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Section: Introductionmentioning

confidence: 88%

Influence of Block form on the Shear Behaviour of Soft Soil–Rock Mixtures by 3D Block Modelling Approaches

et al. 2022

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“…In such metamorphic rocks, a well-developed flaky structure can be observed. This structure makes the mechanical properties different from other rocks (Xu et al, 2018;Liu et al, 2020). In this area, the phyllite bimrocks (Figure 1B) composed of phyllite blocks and phyllite soil are also widely distributed, resulting in a large number of geological hazards.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on Non-Darcian Flow in Phyllite Bimrocks With the Orientation of Blocks

et al. 2022

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Phyllite bimrocks are widely distributed in the eastern margin of the Tibetan Plateau, and it is the main geomaterial for landslides, slopes, dam basement and subgrades in this area. However, the flow behavior of phyllite bimrocks is unknown, especially the flow behavior of phyllite bimrocks with the orientation of blocks. This paper reports the coupling characteristics of flow and orientation of blocks in phyllite bimrocks. The flow behavior of phyllite bimrocks with different block percentages and block sizes was studied by a series of permeability experiments. A large-scale permeability apparatus was designed, and specimens with varying percentages of block and block sizes were produced by the same dip angle of blocks and compaction degree. Based on the Reynolds number analysis, it was found that the flow in phyllite bimrocks becomes laminar to turbulent under lower hydraulic gradient, and the flow behavior of phyllite bimrocks does not obey Darcy’s law. Furthermore, the Forchheimer equation is better at analyzing the flow behavior of phyllite bimrocks compared with Izbash equation. In addition, based on the coefficients a in the Forchheimer equation, the hydraulic conductivity of phyllite bimrocks can be calculated. The calculation result shows that when the percentage of blocks is 25%, the hydraulic conductivity reaches the minimum. Besides, the hydraulic conductivity increases approximately linear with the block size increase. On the basis of previous studies, coefficients A and B of the Forchheimer equation are detected by the normalized objective function analysis. The results would provide a valuable reference for risk assessment and prevention of phyllite bimrock slope.

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“…Xu et al [2] found that water content and a weak plane-loading angle can significantly affect the creep deformation of phyllite. Liu et al [3] found that moderately and slightly weathered phyllite could be used as subgrade filling, and a weathered phyllite filling with 55% rock had a wider particle distribution and experienced the least breakage, making it suitable for filling subgrade. After full weathering, the fragmentation of debris increases significantly, which will make phyllite have the following characteristics: a high liquid limit, difficult compaction, low bearing capacity of rolled subgrade, low cohesion, high dispersion, and a high no loading swelling ratio [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Synergistic Effects of Red Clay and Lime for Improving Phyllite Soil

Zhao,

Cheng

et al. 2023

Minerals

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Phyllite soil and red clay belong to the soils that negatively impact the engineering performance of railway subgrade and may cause subgrade bulges, uneven subgrade settlement, and other subgrade distresses. In order to make full use of these two soils, a collaborative improvement plan was proposed. A series of tests were conducted to analyze the synergistic effects of lime and red clay on the improvement of phyllite soil. The tests included the no loading swelling ratio, swelling pressure, consolidation, and direct shear tests. Additionally, scanning electron microscopy was used to investigate the role of lime and red clay in soil improvement. The test results show that a red clay ratio of 60% + lime content of 3% is the optimal composite improvement scheme. The scheme led to a 93% reduction in the no loading swelling ratio and an 88% reduction in swelling pressure. Additionally, cohesion, the internal friction angle, and the compression modulus increased by 345%, 73%, and 373%. Red clay and lime had weak synergistic improvement effects on the no loading swelling ratio, the swelling pressure, and the internal friction angle of phyllite soil, that is, the synergistic improvement effect of red clay and lime was less than the sum of the single improvement effect but greater than the single improvement effect. Red clay and lime had a strong synergistic improvement effect on the cohesion and the compression modulus of phyllite, that is, the synergistic improvement effect of red clay and lime was greater than the sum of the single improvement effect. The microstructure analysis test results show that red clay can fill the pores of phyllite soil and improve its immediate strength. Through hardening and cementation, lime can enhance the strength of phyllite soil as well as address the issue of the reduced engineering properties of phyllite soil and red clay when exposed to water. Red clay and lime promote each other’s reactions and have a synergistic improvement effect on phyllite soil.

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Effects of initial particle gradation and rock content on crushing behaviors of weathered phyllite fills – A case of eastern Ankang section of Shiyan–Tianshui highway, China

Cited by 14 publications

References 46 publications

Influence of Block form on the Shear Behaviour of Soft Soil–Rock Mixtures by 3D Block Modelling Approaches

Influence of Block form on the Shear Behaviour of Soft Soil–Rock Mixtures by 3D Block Modelling Approaches

Experimental Study on Non-Darcian Flow in Phyllite Bimrocks With the Orientation of Blocks

Synergistic Effects of Red Clay and Lime for Improving Phyllite Soil

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