scholarly journals Influence of shearing rate on the residual strength characteristic of three landslides soils in loess area

2018 ◽  
Author(s):  
Baoqin Lian ◽  
Jianbing  Peng ◽  
Xingang Wang ◽  
Qiangbing Huang
Keyword(s):  
Normal Stress ◽  
Friction Angle ◽  
Slip Zone ◽  
Residual Shear Strength ◽  
Friction Coefficients ◽  
Series Ring ◽  
Loess Area ◽  
Shearing Rate ◽  
The Difference ◽  
Slip Zone Soils

Abstract. In order to investigate the effect of the shearing rate on the residual shear strength of slip zone soils, a series ring shear tests were carried out on slip zone soils from three landslides in loess area at the two shearing rates (0.1 mm/min and 1 mm/min). The slip zone soil specimens used in present study were from the northwest of China. Results indicated that the shear displacement to achieve the residual stage for specimens with higher shearing rate is greater than that of the lower rate. Relationship between the residual friction coefficients and normal stress shows that the residual friction coefficients for all specimens under the lower normal stress were greater than that under the higher normal stress at two shearing rate. Furthermore, the difference in the residual friction angle фr at the two shearing rates, фr (1) − фr (0.1), under each normal stress level were either positive or negative values, with the maximum absolute value of фr (1) − фr (0.1) reach up to 2.218°. However, the difference фr (1) − фr (0.1) under all normal stresses was negative, which indicates that the residual shear parameters reduced with the increasing of the shearing rate in loess area.

scholarly journals Shear rate effect on the residual strength characteristics of saturated loess

2019 ◽  
Author(s):  
Baoqin Lian ◽  
Jianbing Peng ◽  
Qiangbing Huang
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Normal Stress ◽  
Rate Effect ◽  
Shear Tests ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
The Difference

Abstract. Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of ring shear tests were carried out on loess from three landslides at two shear rates (0.1 mm/min and 1 mm/min). Naturally drained ring shear tests results showed that the shear displacement to achieve the residual stage for specimens with higher shear rate was greater than that of the lower rate; both the peak and residual friction coefficient became smaller with increase of shear rate for each sample; at two shear rates, the residual friction coefficients for all specimens under the lower normal stress were greater than that under the higher normal stress. The tests results revealed that the difference in the residual friction angle фr at the two shear rates, фr (1)–фr (0.1), under each normal stress level were either positive or negative values. However, the difference фr(1)–фr (0.1) under all normal stresses was negative, which indicates that the residual shear parameters reduced with the increasing of the shear rate in loess area. Such negative shear rate effect on loess could be attributed to a greater ability of clay particles in specimen to restore broken bonds at low shear rates.

scholarly journals The influence of the grain-size, mineralogical and geochemical composition on the Verdesca landslide

2015 ◽  
Vol 15 (1) ◽  
pp. 135-146 ◽  
Author(s):  
V. Summa ◽  
S. Margiotta ◽  
R. Colaiacovo ◽  
M. L. Giannossi
Keyword(s):  
Grain Size ◽  
Slope Stability ◽  
Size Fraction ◽  
Friction Angle ◽  
Exchange Capacity ◽  
Slip Zone ◽  
Residual Shear Strength ◽  
Geochemical Composition ◽  
Mechanical Characterisation

Abstract. Silty sands and clayey silts taken from a landslide in the Agri Valley have been analysed in order to study the role of sediment composition in the slope stability and the development of a slip zone. A geognostic hole was used to collect samples and monitor movements. A slip zone at a depth of about 14 m was identified. Compositional and physical–mechanical characterisation of samples was carried out. Some compositional characters, such as a 32–2 μm grain-size fraction, clay mineral content, cation exchange capacity and total nitrogen, increase in the slip zone. Some correlations have been found between geotechnical properties (residual shear strength and residual friction angle) and the same compositional characters, which can therefore be considered possible factors influencing slope stability.

scholarly journals The influence of the grain-size, mineralogical and geo-chemical composition on the Verdesca landslide

2014 ◽  
Vol 2 (8) ◽  
pp. 5047-5077 ◽  
Author(s):  
V. Summa ◽  
S. Margiotta ◽  
R. Colaiacovo ◽  
M. L. Giannossi
Keyword(s):  
Grain Size ◽  
Slope Stability ◽  
Mineral Content ◽  
Size Fraction ◽  
Friction Angle ◽  
Exchange Capacity ◽  
Slip Zone ◽  
Residual Shear Strength

Abstract. Silty sands and clayey silts taken from a landslide in the Agri Valley have been analyzed in order to study the role of sediment composition on the slope stability and the development of a slip zone. A geognostic hole was used to collect samples and monitor movements. A slip zone at a depth of about 14 m was identified. Compositional and physical-mechanical characterization of samples were carried out. Some compositional characters, such as 32–2 μm grain-size fraction, clay mineral content, Cation Exchange Capacity and total nitrogen, increase in the slip zone. Some correlations have been found between geotechnical properties (residual shear strength and residual friction angle) and the same compositional characters, which can therefore be considered possible factors influencing slope stability.

scholarly journals Shear rate effect on the residual strength characteristics of saturated loess in naturally drained ring shear tests

2020 ◽  
Vol 20 (10) ◽  
pp. 2843-2856
Author(s):  
Baoqin Lian ◽  
Xingang Wang ◽  
Jianbing Peng ◽  
Qiangbing Huang
Keyword(s):  
Shear Strength ◽  
Shear Rate ◽  
Normal Stress ◽  
Rate Effect ◽  
Shear Tests ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Tests ◽  
The Difference

Abstract. Residual shear strength of soils is an important soil parameter for assessing the stability of landslides. To investigate the effect of the shear rate on the residual shear strength of loessic soils, a series of naturally drained ring shear tests were carried out on loess from three landslides at two shear rates (0.1 and 1 mm min−1). Experimental results showed that the shear displacement to achieve the residual stage for specimens with higher shear rate was greater than that of the lower rate; both the peak and residual friction coefficient became smaller with increase in shear rate for each sample; at two shear rates, the residual friction coefficients for all specimens under the lower normal stress were greater than those under the higher normal stress. Moreover, specimens with almost the same low fraction of clay (CF) showed a similar shear rate effect on the residual friction coefficient, with normal stress increasing, whereas specimens with high CF (24 %) showed a contrasting tendency, indicating that such an effect is closely associated with CF. The test results revealed that the difference in the residual friction angle ϕr at the two shear rates, ϕr(1)−ϕr(0.1) under each normal stress level are either positive or negative values, of which the maximum magnitude is about 0.8∘. However, the difference ϕr(1)−ϕr(0.1) determined under all normal stress levels was negative, which indicates that the residual shear parameters reduced with the increasing of the shear rate in the loess area. Such a negative shear rate effect on loess could be attributed to a greater ability of clay particles in specimens to restore broken bonds at low shear rates.

Theoretical study of the double concave friction pendulum system under variable vertical loading

2019 ◽  
Vol 22 (8) ◽  
pp. 1998-2005 ◽  
Author(s):  
Fangyuan Zhou ◽  
Weilin Xiang ◽  
Kun Ye ◽  
Hongping Zhu
Keyword(s):  
Theoretical Study ◽  
Earthquake Excitation ◽  
Friction Coefficients ◽  
Pendulum System ◽  
Vertical Loading ◽  
Sliding Surfaces ◽  
Vertical Ground ◽  
The Difference ◽  
Friction Pendulum ◽  
Friction Pendulum System

The double concave friction pendulum system has been recognized as an efficient device for decreasing the seismic response of a structure during an earthquake excitation. Previous studies have focused mainly on the properties of the double concave friction pendulum system under constant vertical loading, and the width of the hysteretic loop changed by the vertical ground motion is less considered. In view of this, a theoretical study of the double concave friction pendulum system under variable vertical loading is conducted in this article. Meanwhile, the properties of the hysteretic loops of the double concave friction pendulum system with different friction coefficients between the articulated slider with the upper and lower sliding surfaces are investigated. The results show that the hysteretic loops of the double concave friction pendulum system will be affected by the variation of the vertical loading and the difference of the friction coefficients between the articulated slider with the upper and lower sliding surfaces.

scholarly journals Study on Treatment of Loess Landslide Based on Nanosilica and Fly Ash Composite Stabilizer Filling Fissures

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Jiulong Gao ◽  
Jiading Wang ◽  
Yao Wei ◽  
Shaotong Jiao ◽  
Meng Jing ◽  
...  
Keyword(s):  
Slope Stability ◽  
Early Stage ◽  
Friction Angle ◽  
Threshold Value ◽  
Test System ◽  
Slip Zone ◽  
Loess Landslide ◽  
Material Content ◽  
Grouting Material ◽  
Weak Surface

Frequent occurrence of landslides has seriously threatened the infrastructural projects in the Loess Plateau, China. At the beginning, with development of the landslide, several fissures were generated along the internal weak surface. Then, under the constant influence of rainfall and irrigation, the fissures were expanded and connected, which formed a consecutive sliding surface, consequently leading to the occurrence of the landslide. Therefore, the key to treat the landslide is to prevent the expansion and connection of fissures in the potential slip zone inside the slope. In this paper, an old landslide, which occurred at an early stage of the construction of the Lvliang Airport, was selected as a case study. A new type of grouting material was used to fill the fissures and reinforce the loess in the slip zone, so as to study the effect of material content on the slope stability. With current methods, loess specimens were taken from the slip zone inside the Lvliang Airport slope. Based on the GDS triaxial test system, a series of laboratory tests were performed on the undisturbed loess and the remolded which contained the stabilizer, including triaxial shear tests at constant matric suctions and wetting tests at constant deviator stresses. Moreover, the dichotomy in mathematics was chosen to find the threshold of the material content. The test results showed that the cohesion and the internal friction angle of the loess obviously increased after grouting. The failure behaviour of the loess along the wetting path was dependent on the material ratio and the stress level. Meanwhile, the critical state line of the slope, grouted with materials of different ratios, was compared by fitting the regression equation. It was found that the threshold value of the stabilizer content was between 15% and 20%, which was the most suitable ratio for improving slope stability with relatively lower cost.

scholarly journals Determination of Wheel-Rail Contact Characteristics by Creating a Special Program for Calculation

2014 ◽  
Vol 10 (3) ◽  
pp. 48-59 ◽  
Author(s):  
Ioan Sebeşan ◽  
Yahia Zakaria
Keyword(s):  
Normal Stress ◽  
Contact Zone ◽  
Experimental Results ◽  
Programming Environment ◽  
Special Program ◽  
Friction Coefficients ◽  
Future Developments ◽  
Working Quality ◽  
Contact Ellipse

Abstract The authors in this paper describe the steps of creating a special program in GUI tool in Matlab. The program is designed to calculate the main properties of wheel-rail contact zone, such as: contact ellipse dimensions, normal stress and friction coefficients. All the relevant equations, which were introduced by different researchers, are firstly presented and modified to be applicable to the programming environment, and then the program was built. In the end, the program working quality is discussed and some expected future developments on this program are suggested. The proposed program can make the comparison between theoretical and experimental results, when they are available, easier and faster.

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