scholarly journals Deformation Development Mechanism in a Loess Slope With Seepage Fissures Subjected to Rainfall and Traffic Load

2021 ◽  
Vol 9 ◽  
Author(s):  
Xianlun Leng ◽  
Chuan Wang ◽  
Juan Zhang ◽  
Qian Sheng ◽  
Shengliang Cao ◽  
...  
Keyword(s):  
Water Content ◽  
Transverse Isotropy ◽  
Deformation Modulus ◽  
Traffic Load ◽  
Elastic Model ◽  
Mechanical Parameters ◽  
Loess Slope ◽  
Water Sensitivity ◽  
Mathematical Expressions ◽  
Development Mechanism

Loess landslides induced by rainfall and traffic load are significant hazards during the construction and operation of highways in many loess-covered areas. Studies of the deformation and stability of loess slopes with seepage fissures are limited. In the study, a case study of the Yangpoyao loess slope with seepage fissures in China’s Loess Plateau was conducted to reveal the deformation development mechanism and assess the landslide hazards of such fissured loess slopes. First, the hydraulic-mechanical properties of the Q2 loess were investigated through experiments, and the mathematical expressions of the relationships between various mechanical parameters and water content were fitted, indicating that the mechanical parameters, such as cohesion, angle of internal friction, and deformation modulus, vary in a quasi-linear manner with the water content. Then, a new numerical method was proposed to simulate the mechanical behaviours of the loess considering its water sensitivity and transverse isotropy, where the water sensitivity was considered through the implementation of the mathematical expressions of the hydraulic-mechanical relationships, and the transverse isotropy was considered by the modified constitutive model that combined the logics of transversely elastic model and a ubiquitous-joint model. Finally, the deformation development mechanism of the fissured loess slope under rainfall and traffic load was revealed by using the proposed method. The roles of the rainfall and traffic load in the fissure propagation and deformation development process of the slope were explored, and some stabilisation measures are recommended for the prevention of its failure. The proposed method and findings arising therefrom may provide references for future studies of the stability and landslide hazard assessment of fissured loess slopes.

scholarly journals Distribution Pattern of Anchorage Stress and Water Sensitivity Analysis of Red Clay

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Lifeng Li ◽  
Weili Gong ◽  
Huilin Deng ◽  
Xiaohu Zhang ◽  
Gan Li
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Distribution Pattern ◽  
Water Content ◽  
Exponential Distribution ◽  
Red Clay ◽  
Anchor Cable ◽  
Water Sensitivity ◽  
The Relationship ◽  
Single Exponential

Red clay is a special soil layer with complex engineering properties distributed in tropical and subtropical regions. An anchor cable support is a common form of red clay slope support. The effectiveness of the anchor cable support is mainly determined by the anchoring force provided by the red clay stratum. Increase of the water content will lead to the rapid deterioration of the mechanical properties of red clay, which will lead to the reduction of the anchoring force of the slope anchor cable and lead to the failure of the support. Based on the classical Phillips and uniform anchorage shear stress distribution theory, this paper puts forward a uniform-exponential distribution pattern of anchorage shear stress according to the specific characteristics of red clay by using the characteristics of the peak shear strength and residual shear strength of the rock and soil mass. With increasing anchorage force, the dynamic evolution (single exponential distribution ⟶ double single exponential distribution ⟶ uniform index exponential complex distribution ⟶ uniform distribution) of the anchorage shear stress is analysed. Based on the peak and residual test of the cohesive force and internal friction angle, the relationship between the anchoring force and buried depth and water content is established by analysing the factors influencing the anchoring force. It can be found from the field test that, according to the relationship established, the limit anchorage force of the anchor cable in the red clay stratum can be calculated and the water sensitivity of the anchor cable’s limit anchorage force can be quantitatively analysed.

An Experimental Study on the Mechanical Properties of Soils of the Landslide Induced by Rainfall

2011 ◽  
Vol 90-93 ◽  
pp. 1303-1306
Author(s):  
Dong Heng Hao ◽  
Jian Feng Qi ◽  
Bin Wang ◽  
Shu Qin Zhao
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Internal Friction ◽  
Water Content ◽  
Strain Softening ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Strain Stress ◽  
Geotechnical Tests ◽  
Sliding Zone

Geotechnical tests are performed to study the strain-stress behavior and mechanical parameters by using the automatic KTG triaxial shear apparatus. This study shows that the strain softening phenomenon emerges after the peak values of strain-stress relations appear for the sliding-body soils, and that the strain-stress relations are in the sate of strain hardening all the time for the sliding-zone soils although the water content keeps sameness. The variation laws of cohesion and internal friction angle with water content are respectively consistent with an exponential function and linear relation.

Estimation of Rock Mass Deformation Modulus in Gas Pipeline Area Based on Different Methods

2012 ◽  
Vol 204-208 ◽  
pp. 727-731
Author(s):  
Yuan Zhao ◽  
Liang Qing Wang ◽  
Ye Liang
Keyword(s):  
Rock Mass ◽  
Slope Stability ◽  
Engineering Design ◽  
Deformation Modulus ◽  
Gas Pipeline ◽  
Mechanical Parameters ◽  
Strength Parameters ◽  
Rock Mass Deformation ◽  
Mass Classification ◽  
Mass Deformation

Deformation modulus plays an important role in evaluating slope stability of rock mass and conducting the geotechnical engineering design. Based on the research of geological properties, physical and mechanical parameters of predominant rock mass types for different formations from Zhongxian to Wuhan, China, deformation modulus values of gas pipeline area were estimated by using rock mass classification method in this paper. Comparisons were made amongst different formulas based on GSI, RMR and Q methods to suggest range values of deformation modulus for predominant rock mass types of different formations which gives instructions to estimate strength parameters of rock masses for similar projects.

scholarly journals Shear strength of compacted Chlef sand: effect of water content, fines content and others parameters

2020 ◽  
Vol 42 (1) ◽  
pp. 18-35 ◽  
Author(s):  
Djamel Bouri ◽  
Abdallah Krim ◽  
Abdelkader Brahim ◽  
Ahmed Arab
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Laboratory Study ◽  
Significant Influence ◽  
Mechanical Behaviour ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Fines Content ◽  
Dense State

AbstractThis paper presents a laboratory study of the combined effect of the water content and fines content on the mechanical behaviour of Chlef sand in a medium dense state (RD = 65%) and dense state (RD = 80%). Several mechanical parameters were evaluated such as shear strength, cohesion and friction angle at different water content w = 0, 1, 2 and 3% and different fines content Fc = 0, 10, 20, 30 and 40%. The test results showed that the shear strength of Chlef sand decrease with the increase fines content Fc = 0 to 40%, our tests result also showed that the water content has a significant influence on the shear strength which decreases with the increase in the water content w = 0 to 3%. The fines content and the water content have a significant influence on the mechanical parameters c and φ. Cohesion increases with the percentage of fines and decreases with the increase of the water content while the friction angle decreases with the increase the fines content and the water content.

scholarly journals ISSUES OF IMPROVING THE SEMIEMERIC MODEL OF SOIL FOR DETERMINING ITS WATER CONTENT

2020 ◽  
pp. 63-67
Author(s):  
F. Т. Kazimova ◽  
Keyword(s):  
Water Content ◽  
High Efficiency ◽  
Soil Analysis ◽  
Semiempirical Model ◽  
Starting Position ◽  
Reflection Model ◽  
Mathematical Expressions ◽  
Measuring Signal ◽  
Remote Sensing Methods ◽  
Error Of Measurement

The article is devoted to modeling the process of determining the water content of the soil. Monitoring of soil water content can be conducted using various contact methods, including gravimetric, electromagnetic, thermal, and other methods. The most promising method is considered to be hyperspectral, where the measuring signal is dependent on the color of the soil and its texture, as well as on the content of organic substances in it. In General, remote sensing methods with higher resolution rates both in time and in space allow us to achieve high efficiency in solving this issue. The proposed method of calibration of a known model uses as a starting position a known model relationship between the percentage of water content of the soil and quantity of reflected signal, averaged over all types of soil. Analysis of the well-known method of the inverse semiempirical model of the reflection signal showed that for the accurate realization of this method, used semiempirical model itself must be pre-calibrated. It is shown that an exponential generalized model developed on the basis of data from the XS1 SPOT channel can be used for preliminary calibration of the semiempirical model. Expressions are obtained for performing preliminary calibration of the semiempirical model and thus eliminating the error of measurement of the “miss” type when realizing this method using the inverse semiempirical reflection model. Despite the use of different wavelength ranges, obtaining the same mathematical expressions of the two models under consideration allows to make preliminary calibration of the semiempirical model used to determine the water content of the soil.

scholarly journals Experimental Study on the Mechanical Behavior of Yunnan Limestone in Natural and Saturated States

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Xutao Zhang ◽  
Mingyang Ren ◽  
Zhaobo Meng ◽  
Baoliang Zhang ◽  
Jinglong Li
Keyword(s):  
Elastic Modulus ◽  
Mechanical Behavior ◽  
Water Content ◽  
Failure Modes ◽  
Shear Failure ◽  
Mechanical Response ◽  
Deformation Modulus ◽  
Confining Pressure ◽  
Hyperbolic Function ◽  
Test Results

Rock material is a kind of mineral assemblage with complex structural heterogeneity, whose mechanical behavior is strongly affected by water or moisture content. In this work, we carried out a series of laboratory tests to investigate the mechanical response (e.g., deformation, strength, and failure characteristics) of Yunnan limestone in natural and saturated states. Our test results show that (1) after saturation, the stiffness and strength of Yunnan limestone degenerate considerably. Compared with the natural condition, the elastic modulus, deformation modulus, and tensile modulus decrease by about 30% on average, and uniaxial compressive strength and tensile strength also decrease by about 15% and 20%, respectively. While Poisson’s ratio is less affected by water content, it can be regarded as a constant; (2) the elastic modulus and deformation modulus of Yunnan limestone are significantly affected by confining pressure, and the relationship between them and confining pressure satisfies the law of hyperbolic function; (3) the peak strength envelope of Yunnan limestone has significant nonlinear characteristics, which can be well described by generalized Hoek-Brown strength criterion. However, the generalized Hoek-Brown criterion does not apply to the residual strength, which shows a linearly increasing trend with the increasing confining pressure; (4) the failure modes of Yunnan limestone are significantly dependent on confining pressure but insensitive to water content. With the increasing confining pressure, the failure modes of Yunnan limestone transform from splitting failure, tension-shear mixed failure, single inclined plane shear failure to Y-shaped or X-shaped conjugated shear failure. The test results can provide important experimental data for the establishment of the constitutive model of Yunnan limestone, which will contribute to obtain more reliable results for stability assessment of Xianglu Mountain Tunnel.

Sensitivity Analysis of Soft Rock Mechanics Parameters on Tunnel Mechanics Characteristic

2013 ◽  
Vol 368-370 ◽  
pp. 1756-1761 ◽  
Author(s):  
Feng Shen ◽  
Ying Xu ◽  
Jian Ping Chen ◽  
Chang Qun Zuo
Keyword(s):  
Sensitivity Analysis ◽  
Mechanical Characteristics ◽  
Great Influence ◽  
Deformation Modulus ◽  
Soft Rock ◽  
Friction Angle ◽  
Structure Design ◽  
Surrounding Rock ◽  
Mechanical Parameters ◽  
Stress And Deformation

The physical and mechanical parameters of surrounding rock have great influence on the stability of construction. In order to fully grasp the construction mechanical characteristics of surrounding rock highway tunnel under different mechanical parameters in Wudang schist tunnel, the in-situ measurement and numerical calculation are both used for sensitivity analysis of four mechanical parameters to the mechanical characteristics of surrounding rock-lining. The result shows that the sensitivity of E to deformation of surrounding tunnel is greatest, followed by μ, and both sensitivity far outweigh the one of C, φ. Sensitivity of C, φ on stress around the working face are larger than others. And sensitivities of these parameters to lining are different from stress and deformation. The sequences of sensitivity in a decreasing order, are the deformation modulus, the Poissons ratio, cohesion force and friction angle. However four parameters of sensitivity are not significant. These results provide reference on structure design, construction monitoring, disaster control in soft rock tunnel.

Study about Mechanic Parameter of Slope Rock Mass' Structure Plane

2013 ◽  
Vol 368-370 ◽  
pp. 1551-1555
Author(s):  
Si Yu Wu ◽  
Bo Huang ◽  
Rui Jun Liu
Keyword(s):  
Rock Mass ◽  
Deformation Modulus ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Test Results ◽  
Rock Mass Structure ◽  
Stability Of Slope ◽  
Slope Rock ◽  
The Stability ◽  
Structure Plane

Firstly, the stability of the slope need to determine mechanical parameters of slope rock mass such as deformation modulus, Poissons ratio, cohesion and internal friction angle, etc. For intact rocks, the mechanical parameters mentioned before are easy to determined. While the stability of slope rock mass is controlled by the deformation and intensity. Therefore, how to determine the mechanical parameters of the structure is the key to analyze the stability of slope rock mass. This paper intends to set the slope rock mass below some extra-large bridge as the research object and use numerical calculation to determine the mechanics parameters of rock mass structure plane on the basis of rock sample mechanics test results.

scholarly journals Investigations on Flexural and Compressive Strengths of Mortar Dedicated to Clinker Units—Influence of Mixing Water Content and Curing Time

Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 347
Author(s):  
Jan Kubica ◽  
Iwona Galman
Keyword(s):  
Compressive Strength ◽  
Water Content ◽  
Laboratory Tests ◽  
Bending Strength ◽  
Mechanical Parameters ◽  
Curing Time ◽  
The Impact ◽  
Mixing Water

The article presents laboratory tests on the impact of the mixing water content used in the preparation of fresh mortar on the flexural and compressive strength of one of the dry-mix mortars produced by a leading European producer and dedicated to bricklaying with clinker elements. The development of these parameters in relation to curing time was also analyzed. The mortar samples were prepared from a factory-made mortar mix using 4.0 L (the value recommended by the mortar manufacturer), 4.5 L, and 5 L of water per 25 kg bag of ready-made, pre-mixed dry mortar mix. All samples were tested in five series after 5, 9, 14, 21, and 28 days of sample curing. The results of these tests showed that the use of 6 and 18% more mixing water than recommended by the manufacturer (4.5 and 5 L per bag) adversely affected the basic mechanical parameters of the tested mortar. Moreover, it was found that the highest compressive strength values were obtained after 21 days of curing and not after 28 days as usual. It was also found that hardening time and higher than recommended water content adversely affected the bending strength of the mortar.

Study on Graphic Method for the Stability of High Loess Slopes Based on MATLAB

2014 ◽  
Vol 580-583 ◽  
pp. 148-151
Author(s):  
Jian Chun Hu ◽  
Jian Yong Gao ◽  
Yan Xia Chen
Keyword(s):  
Water Content ◽  
Influencing Factors ◽  
Loess Plateau ◽  
Soil Conservation ◽  
Seismic Intensity ◽  
Important Task ◽  
Graphic Method ◽  
Table Lookup ◽  
Water Sensitivity ◽  
The Stability

High loess slopes are easily unstable because of the water sensitivity of loess, therefore, the study on stability of high loess slopes is a very important task for water and soil conservation on loess plateau. Forcus on the inefficiency of current graphic method, after considering main influencing factors of stability of high loess slopes, such as lithology, topography, groundwater conditions, slope water content and seismic intensity, etc., on the basis of graphic method, an automatic table lookup program was developed, moreover, the interfaces of graphic method were compiled based on MATLAB platform, which could automatically generate plenty of obvious characteristics of slope data for further modeling.

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