The Experts below are selected from a list of 12747 Experts worldwide ranked by ideXlab platform
Enlong Liu - One of the best experts on this subject based on the ideXlab platform.
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a binary medium based constitutive model for artificially cemented gravel Silty Clay mixed soils
European Journal of Environmental and Civil Engineering, 2021Co-Authors: Enlong LiuAbstract:In situ soils of deep overburden layer of dam foundation are widely distributed in Southwest China, which are mixtures of gravel and Silty Clay in varying proportions and have cementation feature b...
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cyclic properties of artificially cemented gravel Silty Clay mixed soils
Experimental Techniques, 2020Co-Authors: Enlong LiuAbstract:The aim of this paper is to provide an insight into the effect of fine content (FC) on the artificially cemented gravel-Silty Clay mixed soils (CMS) in terms of strength, deformation, effective stress path and pore pressure response by undrained cyclic triaxial tests. In addition, some cyclic triaxial tests were also conducted on remolded gravel-Silty Clay mixed soils (RMS) under the same test conditions in order to evaluate the effect of cementation provided by the cementitious material. The corresponding cyclic responses, such as the generation and accumulation of axial strain, pore pressure and effective stress path, are compared across a range of CMS and RMS. A constant 5% percentage (by weight) of calcium oxide in mixed soils with four different ratios of fine content (13%, 30%, 50% and 70%) are tested under four types of confining pressures, 50 kPa, 100 kPa, 200 kPa and 300 kPa respectively. The results demonstrate that: an increase in fine content leads to decrease in both strength and liquefaction resistance, but accelerate the strain accumulation and pore pressure development. The cyclic responses of CMS exhibit “hysteresis” significantly compared with those of RMS due to the bonding strength between soil particles.
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the mechanical characteristics of artificially cemented gravel Silty Clay mixed soils
Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 2020Co-Authors: Enlong LiuAbstract:Triaxial tests were performed on artificially cemented gravel–Silty Clay mixed soils and remoulded samples under consolidated drained conditions. The aim was to investigate the effects of the conte...
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micromechanical analysis of frozen Silty Clay sand mixtures with different sand contents by triaxial compression testing combined with real time ct scanning
Cold Regions Science and Technology, 2019Co-Authors: Ge Zhang, Enlong Liu, Shijie Chen, Bingtang SongAbstract:Abstract Frozen soil-rock mixtures are widely used as geological materials in engineering construction in cold regions. In this paper, a Silty Clay-sand mixture was selected to simulate the mechanical properties of a frozen soil-rock mixture. A series of triaxial compression tests on frozen Silty Clay-sand mixtures with different sand contents of 0%, 10%, 20%, and 40% under confining pressures of 0.5 MPa, 1 MPa, 2 MPa and 3 MPa at −6 °C, respectively, was conducted in combination with real-time computed tomography (CT) scanning. The test results indicate that under the same sand content, the strength of the frozen Silty Clay-sand mixture is maximized when the confining pressure is within the range of approximately 0.5 to 1.0 MPa. By calculating the CT values of all the samples with different sand contents before axial loading, the relationships between the average CT values of the whole samples and the sand contents were determined. In addition, vertical section CT images of the Silty Clay-sand mixture were collected during the loading process. Based on homogenization theory, a macroscopic yield criterion was formulated to describe the nonlinear behavior of the frozen Silty Clay-sand mixture considering the influence of the sand content. The evolution laws of the mean CT values of the whole samples with different sand contents were explored throughout the loading process. The CT value of a whole sample decreases linearly with increasing axial strain. By applying a nonassociated flow rule, an elastoplastic constitutive model was established to consider the influence of sand content. The simulation results of the deviatoric stresses versus axial strains and volumetric strains versus axial strains obtained with the proposed model are in good agreement with the experimental results.
Yanhu Zhao - One of the best experts on this subject based on the ideXlab platform.
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a dynamic strength criterion for frozen sulfate saline Silty Clay under cyclic loading
Cold Regions Science and Technology, 2020Co-Authors: Yanhu Zhao, Yuanming Lai, Jing Zhang, Mengke LiaoAbstract:Abstract The strength properties of frozen saline soils under cyclic loading are more complex than those of unfrozen soils and frozen salt-free soils due to the existence of salt crystals in soil matrix. In this paper, a serious of tri-axial cyclic loading tests are conducted for frozen sulfate saline Silty Clay (FSSSC) with different Na2SO4 contents under different confining pressures and loading dynamic stress ratios at the temperature of −6 °C, respectively. The experimental results illustrate that the dynamic strength of FSSSC decreases with the increase of axial strain. The critical state line of FSSSC under cyclic loading is moving constantly. The dynamic critical state lines of FSSSC with different salt contents are different under same axial strains. The dynamic friction angle of FSSSC is related to salt content, loading dynamic stress ratio and confining pressure. Based on the experimental results, a dynamic strength criterion for FSSSC under cyclic loading is proposed, and the method of determining dynamic strength parameters is given. This strength criterion not only can reflect the effect of loading dynamic stress ratio and salt content on dynamic strength, but also can describe the influence of high confining pressure on dynamic strength.
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an anisotropic bounding surface elastoplastic constitutive model for frozen sulfate saline Silty Clay under cyclic loading
International Journal of Plasticity, 2020Co-Authors: Yanhu Zhao, Fan YuAbstract:Abstract To study the mechanical properties of frozen saline soil under cyclic loading, the cyclic tri-axial compressive experiments of 36 samples are performed for frozen saline Silty Clay with 0.0, 0.5, 1.5 and 2.5% of Na2SO4 contents at the temperature of −6 °C, respectively. The experimental results illustrate that the effect of the salt contents and confining pressures on the strength and deformation properties of frozen sulfate saline soils under cyclic loading is significant. To understand the deformation characteristics of frozen sulfate saline Silty Clay (this kind of saline soil), a bounding surface elastoplastic constitutive model is presented based on the test results and bounding surface plasticity theory. The proposed model includes the effects of salt contents and confining pressures on dynamic characteristics, therefore, it can suitably describe the dynamic stress-strain response of frozen saline soil under cyclic dynamic loading. This proposed model includes: (1) Critical stress ratio calculation formula, considering the effect of salt contents and confining pressures, is proposed. Critical stress ratio and bounding surface shape parameter varying with confining pressures are introduced into plastic potential surface function and bounding surface function to describe pressure melting and crushing characteristics of frozen soils under high confining pressures. (2) The influence of the initial anisotropy and the induced anisotropy by dynamic loads on bounding surface of rotation hardening is considered. A non-associated flow rule together with a mixed hardening rule is used to describe the plastic flow rule and hardening rule of soils during cyclic loading, respectively. (3) A radial mapping rule with mobile mapping origin is employed to simulate elastoplastic properties of soils during cyclic loading. By comparing its simulated results with the test results of cyclic triaxial compression tests, it is found that the proposed model in this paper can well predict deformation characteristics of this kind of saline soil under cyclic loading.
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a nonlinear strength criterion for frozen sulfate saline Silty Clay with different salt contents
Advances in Materials Science and Engineering, 2018Co-Authors: Yanhu Zhao, Yuanming Lai, Jing Zhang, Chong WangAbstract:It has been proven that the mechanical properties of frozen saline soils are different from frozen soils and unfrozen saline soils. In this paper, in order to study the effects of the salt contents on the strength characteristics of frozen soils, a series of conventional triaxial compression tests are carried out for frozen saline Silty Clay with Na2SO4 contents 0.0, 0.5, 1.5, and 2.5% under confining pressures from 0 MPa to 18 MPa at −6°C, respectively. The experimental results show that the strength of frozen saline Silty Clay presents obvious nonlinearity, the strength of frozen saline Silty Clay increases with increasing confining pressures at first, but with a further increase in confining pressures, the strength decreases because of pressure melting and crushing phenomena under high confining pressures, and salt contents have an important influence on strength of frozen saline Silty Clay. A strength criterion is proposed on the basis of the experimental results. The strength criterion could well reflect the nonlinear strength characteristic of frozen saline Silty Clay and the influence of salt contents on frozen saline Silty Clay.
Xiaochuan Ren - One of the best experts on this subject based on the ideXlab platform.
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statistical studies on the pore characteristic of qinghai tibet plateau Silty Clay modified by nano silica
Microporous and Mesoporous Materials, 2021Co-Authors: Chong Wang, Qian Chen, Hao Zhang, Xiaoyu Liu, Xiaochuan RenAbstract:Abstract Nano-particles as additive materials have been widely used in geotechnical engineering, which can significantly improve the strength and suppress cracks formation of geo-materials. Nano-particle modified geo-materials consist of a ruleless distribution of soil particles, nano-particles, water, and gas. Thus, the micro-pore properties of modified geo-materials are uncertain and variable. In addition, the variability phenomenon is intensified by the strong water absorption and adhesive aggregation of nano-silica. However, the micro-pore characteristics of nano-material modified soil and the statistical properties are very limited in literature. To address those, large samples tests on Qinghai-Tibet Plateau Silty Clay ( ≥ 50 specimens) were conducted, and the median pore diameters and cumulative volume of pore diameters smaller than 0.1 μ m at four nano-silica contents (0, 0.75%, 2%, and 5%) were measured by the mercury intrusion porosimetry. The experimental data show that the two micro-pore parameters of fifty Silty Clay specimens with nano-silica additive show noticeable variability. To quantify these variablities, we assume the micro-pore diameter follows one of four probability distributions (normal, lognormal, Weibull, and gamma). The experimental curves were compared with four selected potential probability distributions and it was found that all distributions agreed well with the experimental data, approximatively. Nevertheless, only three distributions (normal, lognormal, and gamma) satisfy the Hypothesis testing. The results of chi-square test indicate that the normal distribution had the smallest effect evaluation index, and it could well describe the micro-pore parameters of nano-silica modified Silty Clay. The results will benefit a better understanding of the changeability of micro-pore characteristics of nano-particle modified geomaterials. Besides, these results are significant for interpreting the micromechanical mechanism of modified soils, and are helpful to guide the selection of additive materials for modified porous media.
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laboratory investigation of the effect of nano silica on unconfined compressive strength and frost heaving characteristics of Silty Clay
Soil Mechanics and Foundation Engineering, 2018Co-Authors: Xiaoqing Chen, Jiangang Chen, Xiaochuan RenAbstract:In order to investigate the effect of nano-silica on the unconfined compressive strength and frost heaving characteristics of Silty Clay, a series of indoor tests of unconfined compressive strength, frost heaving, and mercury intrusion porosimetry (MIP) was done on Silty Clay with different nano-silica content. The unconfined compressive strength of Silty Clay increased with increases in nano-silica content, and increased by 6.65 times when the nano-silica content was 5.0%. However, the frost heaving displacement decreased with increases in the nano-silica content. The results of MIP tests illustrated that the volume and number of large pores decreased, and the volume and numbers of small pores increased with increases in the nano-silica content. An increase in the nano-silica content increased the porosity and decreased the average pore diameter. The formation of viscous gel by addition of nano-silica into Silty Clay enhanced the bonding and filled the gaps between particles of Silty Clay and blocked the migration of water in the soil. The microscopic pore structure of the sample was generally uniform with increasing nano-silica content, which resulted in an increase in unconfined compressive strength and a decrease in frost heaving displacement.
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effect of nanosilica on the physical and mechanical properties of Silty Clay
Nanoscience and Nanotechnology Letters, 2014Co-Authors: Xiaochuan RenAbstract:We investigated the effects of nanosilica on the physical and mechanical properties of Silty Clay through scanning electron microscopy and a series of tests measuring specific gravity, liquid and plastic limits, uniaxial compression, and frost heave. Increasing nanosilica concentration increased the plastic and liquid limits of the Clay as well as its uniaxial compression strength, but decreased the amount of frost heave produced. However, there was no change in the specific gravity of the Clay sample. Further, nanosilica had no effect on the composition of the Clay sample but reduced its average pore size, making its structure more uniform.
Fan Yu - One of the best experts on this subject based on the ideXlab platform.
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an anisotropic bounding surface elastoplastic constitutive model for frozen sulfate saline Silty Clay under cyclic loading
International Journal of Plasticity, 2020Co-Authors: Yanhu Zhao, Fan YuAbstract:Abstract To study the mechanical properties of frozen saline soil under cyclic loading, the cyclic tri-axial compressive experiments of 36 samples are performed for frozen saline Silty Clay with 0.0, 0.5, 1.5 and 2.5% of Na2SO4 contents at the temperature of −6 °C, respectively. The experimental results illustrate that the effect of the salt contents and confining pressures on the strength and deformation properties of frozen sulfate saline soils under cyclic loading is significant. To understand the deformation characteristics of frozen sulfate saline Silty Clay (this kind of saline soil), a bounding surface elastoplastic constitutive model is presented based on the test results and bounding surface plasticity theory. The proposed model includes the effects of salt contents and confining pressures on dynamic characteristics, therefore, it can suitably describe the dynamic stress-strain response of frozen saline soil under cyclic dynamic loading. This proposed model includes: (1) Critical stress ratio calculation formula, considering the effect of salt contents and confining pressures, is proposed. Critical stress ratio and bounding surface shape parameter varying with confining pressures are introduced into plastic potential surface function and bounding surface function to describe pressure melting and crushing characteristics of frozen soils under high confining pressures. (2) The influence of the initial anisotropy and the induced anisotropy by dynamic loads on bounding surface of rotation hardening is considered. A non-associated flow rule together with a mixed hardening rule is used to describe the plastic flow rule and hardening rule of soils during cyclic loading, respectively. (3) A radial mapping rule with mobile mapping origin is employed to simulate elastoplastic properties of soils during cyclic loading. By comparing its simulated results with the test results of cyclic triaxial compression tests, it is found that the proposed model in this paper can well predict deformation characteristics of this kind of saline soil under cyclic loading.
Chong Wang - One of the best experts on this subject based on the ideXlab platform.
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statistical studies on the pore characteristic of qinghai tibet plateau Silty Clay modified by nano silica
Microporous and Mesoporous Materials, 2021Co-Authors: Chong Wang, Qian Chen, Hao Zhang, Xiaoyu Liu, Xiaochuan RenAbstract:Abstract Nano-particles as additive materials have been widely used in geotechnical engineering, which can significantly improve the strength and suppress cracks formation of geo-materials. Nano-particle modified geo-materials consist of a ruleless distribution of soil particles, nano-particles, water, and gas. Thus, the micro-pore properties of modified geo-materials are uncertain and variable. In addition, the variability phenomenon is intensified by the strong water absorption and adhesive aggregation of nano-silica. However, the micro-pore characteristics of nano-material modified soil and the statistical properties are very limited in literature. To address those, large samples tests on Qinghai-Tibet Plateau Silty Clay ( ≥ 50 specimens) were conducted, and the median pore diameters and cumulative volume of pore diameters smaller than 0.1 μ m at four nano-silica contents (0, 0.75%, 2%, and 5%) were measured by the mercury intrusion porosimetry. The experimental data show that the two micro-pore parameters of fifty Silty Clay specimens with nano-silica additive show noticeable variability. To quantify these variablities, we assume the micro-pore diameter follows one of four probability distributions (normal, lognormal, Weibull, and gamma). The experimental curves were compared with four selected potential probability distributions and it was found that all distributions agreed well with the experimental data, approximatively. Nevertheless, only three distributions (normal, lognormal, and gamma) satisfy the Hypothesis testing. The results of chi-square test indicate that the normal distribution had the smallest effect evaluation index, and it could well describe the micro-pore parameters of nano-silica modified Silty Clay. The results will benefit a better understanding of the changeability of micro-pore characteristics of nano-particle modified geomaterials. Besides, these results are significant for interpreting the micromechanical mechanism of modified soils, and are helpful to guide the selection of additive materials for modified porous media.
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a nonlinear strength criterion for frozen sulfate saline Silty Clay with different salt contents
Advances in Materials Science and Engineering, 2018Co-Authors: Yanhu Zhao, Yuanming Lai, Jing Zhang, Chong WangAbstract:It has been proven that the mechanical properties of frozen saline soils are different from frozen soils and unfrozen saline soils. In this paper, in order to study the effects of the salt contents on the strength characteristics of frozen soils, a series of conventional triaxial compression tests are carried out for frozen saline Silty Clay with Na2SO4 contents 0.0, 0.5, 1.5, and 2.5% under confining pressures from 0 MPa to 18 MPa at −6°C, respectively. The experimental results show that the strength of frozen saline Silty Clay presents obvious nonlinearity, the strength of frozen saline Silty Clay increases with increasing confining pressures at first, but with a further increase in confining pressures, the strength decreases because of pressure melting and crushing phenomena under high confining pressures, and salt contents have an important influence on strength of frozen saline Silty Clay. A strength criterion is proposed on the basis of the experimental results. The strength criterion could well reflect the nonlinear strength characteristic of frozen saline Silty Clay and the influence of salt contents on frozen saline Silty Clay.
