Study of the Effect of Shear Rates on Residual Shear of Landslide Soil

2013 ◽  
Vol 639-640 ◽  
pp. 598-601
Author(s):  
Chuan Sheng Chen ◽  
Jing Fang Liu ◽  
Shi Zhi Wen
Keyword(s):  
Friction Coefficient ◽  
Residual Strength ◽  
Slip Surface ◽  
Shear Behaviour ◽  
Residual Shear Strength ◽  
Shear Rates ◽  
Ring Shear ◽  
Ring Shear Apparatus ◽  
The Stability ◽  
Landslide Slope

The residual strength is one of the most important strength parameters to evaluate the stability of a reactivated landslide slope, but the relation between residual strength gained by using ring shear tests and shear speed still remains unclear. In order to clarify the relationship between them, the variation in residual friction coefficient of slip surface soils with shearing rates were calculated and discussed in this paper by means of an undrained ring shear apparatus on Miaowan sample of China-Loess Plateau , predominantly consists of silty-sandy(81.3%), and Kamenose sample of Japan, predominantly consists of clay(73.2%) in texture .The residual friction coefficient was observed to be lower for higher shear rates in Kamenose sample;while the variation of its shear behaviour at different shear rates is fluctuant in Miaowan sample. This change in pore water pressures and soil texture could be thought as the rate effect mechanism of residual shear strength.

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.

Residual strength of smectite-dominated soils from the Kamenose landslide in Japan

1987 ◽  
Vol 24 (3) ◽  
pp. 456-462 ◽  
Author(s):  
Seiichi Gibo ◽  
Kazuhiko Egashira ◽  
Masami Ohtsubo
Keyword(s):  
Residual Strength ◽  
Shear Test ◽  
Slip Surface ◽  
Clay Fraction ◽  
Particle Orientation ◽  
Shear Mode ◽  
Ring Shear Test ◽  
Ring Shear ◽  
Shearing Resistance ◽  
Clay Fraction Content

The residual strength of smectite-dominated soils from the main slip surfaces of the Kamenose landslide, Japan, was measured by ring shear test, and the relations of the residual strength to the clay fraction content and clay particle orientation were studied. The residual angles of shearing resistance, [Formula: see text], were estimated assuming that the residual cohesion is zero. The magnitude of the residual angle of shearing resistance was dependent on the <2-μm clay fraction content, CF, and on the effective normal stress, [Formula: see text], because of curved strength lines. At [Formula: see text] equivalent to the overburden pressures, the soils had [Formula: see text] of 6–8°. These residual angles of shearing resistance were fitted on the [Formula: see text] – CF line for sand–bentonite mixtures, and exhibited the sliding shear mode.The orientation of smectite particles on shear surfaces showing slickensides was assessed by X-ray diffraction technique. The orientation of smectite particles was found to reduce the residual strength considerably, and this orientation effect was revealed more clearly at low effective normal stresses. Key words: residual strength, particle orientation, landslide, smectite, shear mode, slip surface, slickenside, clay mineral, physicochemical properties, ring shear test.

A New Ring Shear Apparatus and Its Application to the Measurement of Residual Strength

Géotechnique ◽  
1971 ◽  
Vol 21 (4) ◽  
pp. 273-328 ◽  
Author(s):  
A. W. Bishop ◽  
G. E. Green ◽  
V. K. Garga ◽  
A. Andresen ◽  
J. D. Brown
Keyword(s):  
Residual Strength ◽  
Ring Shear ◽  
Ring Shear Apparatus

Strain Softening Behaviors of Clay under Fast Ring Shear Conditions

2012 ◽  
Vol 446-449 ◽  
pp. 1880-1883
Author(s):  
Yong Hong ◽  
Jun Gang Wang
Keyword(s):  
Pore Pressure ◽  
Strain Softening ◽  
Strength Reduction ◽  
The Other ◽  
Silty Clay ◽  
Shear Tests ◽  
Shear Rates ◽  
High Shear Rates ◽  
Ring Shear ◽  
Ring Shear Apparatus

In this study, the strain softening behaviors of an overconsolidated silty clay was studied by a ring shear apparatus. The tested results present some different properties with the traditional shear tests. It was found that the silty clay samples with relatively high shear rates are liable to the occurrence of strain softening. With shear rate increasing, both the peak strengths and the post-peak strength reduction become greater. According to the data of deformation and pore pressure measured during the tests, there are two patterns of causing the strain softening of the silty clay. One is related with the contraction of soil specimens; the other is concerned with the generation of negative pore pressure due to the dilatancy of soil body.

scholarly journals Rate Effects on Peak and Residual Strengths of Overconsolidated Clay in Ring Shear Tests

2021 ◽  
Author(s):  
Nguyen Thanh Duong ◽  
Motoyuki Suzuki
Keyword(s):  
Shear Strength ◽  
Residual Strength ◽  
Clayey Soil ◽  
Shear Displacement ◽  
Shear Tests ◽  
Shear Rates ◽  
Ring Shear ◽  
Wide Range ◽  
Rate Effects ◽  
Ring Shear Tests

Overconsolidated (OC) clay soil is widely distributed in landslide slopes. This soil is often fissured, jointed, contains slickensides, and is prone to sliding. Thus, the shear strength behavior of OC clayey soil is complicated and has received much attention in the literature and in practice in terms of evaluating and predicting landslide stability. However, the behavior of the shear strength of OC clayey soil at different shear rates, as seen in ring shear tests, is still only understood to a limited extent and should be examined further, especially in terms of the residual strength characteristics. In this study, a number of ring shear tests were conducted on kaolin clay at overconsolidation ratios (OCRs) ranging from 1 to 6 under different shear displacement rates in the wide range of 0.02 mm/min to 20.0 mm/min to investigate the shear behavior and rate dependency of the shear strength of OC clay. Variations in the cohesion and friction angles of OC clay under different shear rates were also examined. The results indicated that the rate effects on the peak strength of OC and normally consolidated (NC) clays are opposite at fast shear displacement rates. At the residual state, as with NC clay, the positive rate effect on the residual strength is also exhibited in OC clay, but at a lower magnitude. Regarding the shear strength parameters, the variations in the cohesion and friction angles of OC clay at different shear rates were found to be different at peak and residual states.

scholarly journals Influence of the Geometry Alteration of the Landslide Slope on its Stability: A Case Study in the Carnian Alps (Italy)

2017 ◽  
Vol 64 (2) ◽  
pp. 101-114 ◽  
Author(s):  
Lesław Zabuski ◽  
Giulia Bossi ◽  
Gianluca Marcato
Keyword(s):  
Cross Sections ◽  
Slip Surface ◽  
Monitoring Data ◽  
Stability Conditions ◽  
Control Points ◽  
Tagliamento River ◽  
The Stability ◽  
Landslide Slope ◽  
National Road

Abstract The paper presents the principles of the slope reprofiling and proves the effectiveness of this stabilization measure. The case study of two adjacent landslides in the National Road 52 “Carnica” in the Tagliamento River valley, the Carnian Alps (46°23′49″N, 12°42′51″E) are the example allowing for illustration of this approach. The phenomena have been studied for more than a decade, making it possible to carry out a detailed geological and geomorphological reconstruction. That was done on the basis of a large amount of monitoring data collected during that period. Since the landslides are threatening an important road, countermeasure works to ameliorate the stability conditions of the slides need to be designed. The paper focuses on the creation of a numerical model consistent with monitoring data and capable of reconstructing the dynamics of both landslides. Two cross-sections, one for each landslide, were selected for the analysis. The geometry of the slip surface was determined on the basis of control points, such as slip surface readings from inclinometers, and geomorphological evidence for the contour. The FLAC2D code was used to evaluate the current stability of these landslides and to determine the effectiveness of changing the slope geometry by removing material from the upper part of the slope and putting it to the lowest part as reinforcement.

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.

Sign in / Sign up

Export Citation Format

Share Document