Shear Strength of Aeolian Sand Sediments

2018 ◽  
Vol 61 (2) ◽  
pp. 583-590 ◽  
Author(s):  
Fang Yi ◽  
Cheng Hong ◽  
Zou Xueyong ◽  
Zhang Kaidi
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Bulk Density ◽  
Normal Stress ◽  
Friction Velocity ◽  
Friction Angle ◽  
Aeolian Sand ◽  
Threshold Friction Velocity ◽  
Sand Sediments ◽  
Grain Diameter

Abstract. The anti-erodibility of aeolian sand sediments represents their resistance to airflow shear and is closely associated with soil shear strength. However, there have been few studies on the anti-erodibility of sediments from the perspective of shear strength. In this study, we performed shear strength experiments for four categories of sediments at different values of normal stress. All samples were oven-dried prior to the shear tests. The main conclusions were as follows. The shear strength of sediments increased linearly with normal stress and grain diameter. Organic matter may weaken the shear strength. The impact of bulk density and CaCO3 content on the shear strength did not follow consistent rules, but RCaCO3/RBulk (where RCaCO3 is the ratio of CaCO3 content between two samples, and RBulk is the difference in bulk density) determines the relative contribution of each factor to shear strength. The cohesion, internal friction angle, and shear strength increased with increasing grain diameter. They also increased with increasing sorting coefficient when the sorting coefficient was greater than 0.6, while the opposite trend occurred with sorting coefficients less than 0.6. There was a positive linear correlation between cohesion and threshold friction velocity (R2 = 0.91). This study improves our understanding of shear strength, providing basic data with which to construct a dynamic model of aeolian sand transport by wind action. Keywords: Bulk density, Cohesion, Grain diameter, Internal friction angle, Shear strength, Sorting coefficient, Threshold friction velocity.

Characterization of Shear Strength and Interface Friction of Organic Soil

2020 ◽  
Vol 857 ◽  
pp. 203-211
Author(s):  
Majid Hamed ◽  
Waleed S. Sidik ◽  
Hanifi Canakci ◽  
Fatih Celik ◽  
Romel N. Georgees
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Friction Angle ◽  
Structural Materials ◽  
Organic Soil ◽  
Internal Friction Angle ◽  
Interface Friction

This study was undertaken to investigate some specific problems that limit a safe design and construction of structures on problematic soils. An experimental study was carried out to examine the influence of loading rate and moisture content on shear strength of organic soil. Influece of moisture content on interface friction between organic soil and structural materials was also attempted. A commonly used soil in Iraq was prepared at varying moisture contents of 39%, 57% and 75%. The experimental results showed that the increase in water content will decrease the shear stress and the internal friction angle. An increase of the shearing rate was found to decrease the shear stress and internal friction angle for all percetanges of water contents. Further, direct shear tests were carried out to detect the interface shear stress behavior between organic soil and structural materials. The results revealed that the increase in water content was shown to have significant negetavie effects on the interface internal friction and angle shear strength.

scholarly journals Influence of Structural Plane Microscopic Parameters on Direct Shear Strength

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhui Cheng ◽  
Weijun Yang ◽  
Dongliang He
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Stiffness Ratio ◽  
Structural Plane

Structural plane is a key factor in controlling the stability of rock mass engineering. To study the influence of structural plane microscopic parameters on direct shear strength, this paper established the direct shear mechanical model of the structural plane by using the discrete element code PFC2D. From the mesoscopic perspective, the research on the direct shear test for structural plane has been conducted. The bonding strength and friction coefficient of the structural plane are investigated, and the effect of mesoscopic parameters on the shear mechanical behavior of the structural plane has been analyzed. The results show that the internal friction angle φ of the structural plane decreases with the increase of particle contact stiffness ratio. However, the change range of cohesion is small. The internal friction angle decreases first and then increases with the increase of parallel bond stiffness ratio. The influence of particle contact modulus EC on cohesion c is relatively small. The internal friction angle obtained by the direct shear test is larger than that obtained by the triaxial compression test. Parallel bond elastic modulus has a stronger impact on friction angle φ than that on cohesion c. Under the same normal stress conditions, the shear strength of the specimens increases with particle size. The shear strength of the specimen gradually decreases with the increase of the particle size ratio.

scholarly journals Stabilization of Algerian Clayey Soils with Natural Pozzolana and Lime

2017 ◽  
Author(s):  
Khelifa Harichane ◽  
Mohamed Ghrici ◽  
Said Kenai
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Plasticity Index ◽  
Engineering Properties ◽  
High Plasticity ◽  
Expansive Clay ◽  
Clayey Soils ◽  
Natural Pozzolana

Cohesive soils with a high plasticity index present difficulties in construction operations because they usually contain expansive clay minerals. However, the engineering properties of soils can be improved by different techniques. The aim of this paper is to study the effect of using lime, natural pozzolana or a combination of both lime and natural pozzolana on plasticity, compaction and shear strength of two clayey soils classified as CH and CL according to the unified soil classification system (USCS). The obtained results indicated that for CH class clay soil, the plasticity index decreased significantly for samples stabilized with lime. On the other hand, for the soil classified as CL class clay, a high decrease in the plasticity index value was observed for samples stabilized with natural pozzolana compared to those stabilized with lime. Also, both the cohesion and internal friction angle in lime added samples were demonstrated to increase with time. The combination of lime and natural pozzolana exhibits a significant effect on the enhancement of both the cohesion and  internal friction angle at later stages. The lime-natural pozzolana combination appears to produce higher shear strength parameters than lime or natural pozzolana used alone.

scholarly journals Study on Water Characteristic Curve and Shear Characteristics of Typical Unsaturated Silty Clay in Shaoxing

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Ruiqian Wu ◽  
Youzhi Tang ◽  
Shaohe Li ◽  
Wei Wang ◽  
Ping Jiang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Unsaturated Soil ◽  
Direct Shear Test ◽  
Shear Test ◽  
Characteristic Curve ◽  
Friction Angle ◽  
Matric Suction ◽  
Silty Clay ◽  
Direct Shear

In order to probe into one simplified method to predict the shear strength of Shaoxing unsaturated silty clay, the test method combining unsaturated soil consolidation instrument and conventional direct shear instrument is used to study the shear strength, and the method is compared and verified with the results of equal suction direct shear test. The research results show that the soil water characteristic curve fitted by the measured data points and VG model has obvious stage characteristics in the range of 0~38 kPa, 38~910 kPa, and 910~10000 kPa. The shear strength of unsaturated soil measured by consolidation meter combined with conventional direct shear test is in good agreement with that measured by equal suction direct shear test in the range of 0~500 kPa. The results show that the shear strength, total cohesion, and effective internal friction angle of soil increase slightly with the increase of matric suction in the range of 0~38 kPa. When the matric suction increases from 38 kPa to 500 kPa, the shear strength and total cohesion force of the soil have similar stage characteristics with the SWCC, which first increases and then tends to be stable, while the effective internal friction angle changes slightly. Finally, taking the air-entry value as the demarcation point, an improved model of unsaturated shear strength is proposed by analyzing the error value. Compared with the measured value, the absolute value of relative error is basically kept in the range of 5%~10%, which is close to the measured value.

scholarly journals Determining the Shear Strength and Permeability of Soils for Engineering of New Paddy Field Construction in a Hilly Mountainous Region of Southwestern China

2020 ◽  
Vol 17 (5) ◽  
pp. 1555
Author(s):  
Zhen Han ◽  
Jiangwen Li ◽  
Pengfei Gao ◽  
Bangwei Huang ◽  
Jiupai Ni ◽  
...  
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Engineering Design ◽  
Soil Water ◽  
Soil Water Content ◽  
Paddy Field ◽  
Friction Angle ◽  
Strength Properties ◽  
Mountainous Region

As a constructed wetland ecosystem, paddy field plays an irreplaceable role in flood storage and detention, groundwater replenishment, environmental protection, and ecological balance maintenance. New paddy field construction can give full play to the production and ecological functions of paddy field and can adjust the development structure of the agricultural industry effectively. The soil properties of shear strength and permeability, which provide a theoretical basis for engineering design, construction, and post-operation, are important indexes in the site selection of new paddy field. The shear strength and permeability properties of soils from different land use types (vegetable field, gentle slope dryland, corn field, grapery, and abandoned dryland) for engineering new paddy field construction were investigated in this study. The results showed that the soil water content had a significant effect on the soil shear strength, internal friction angle, and cohesion. The total pressure required for soil destruction decreased with increasing water content under the same vertical pressure, resulting in easier destruction of soils. The internal friction angle decreased with increasing soil water content, and the soil cohesion first increased and then decreased with increasing soil water content. Considering that paddy fields were flooded for a long time, the soil strength properties had certain water sensitivity. Effective measures must be taken to reduce the change in soil water content, so as to ensure the stability of the embankment foundation, roadside ditch foundation, and cutting slope. In addition, the influence of changing soil water content on the strength properties of paddy soils should be fully considered in engineering design and construction, and the soil bulk density at the plough pan should reach at least 1.5 g cm−3 or more to ensure better water retention and the anti-seepage function of paddy field. The study can provide construction technology for engineering new paddy field construction in a hilly mountainous region of southwestern China.

scholarly journals Experimental Study of the Composition and Structure of Granular Media in the Shear Bands Based on the HHC-Granular Model

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
Guang-jin Wang ◽  
Xiang-yun Kong ◽  
Chun-he Yang
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Granular Media ◽  
Random Distribution ◽  
Shear Bands ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Coarse Grained ◽  
Composition And Structure ◽  
Coarse Grained Soil

The researchers cannot control the composition and structure of coarse grained soil in the indoor experiment because the granular particles of different size have the characteristics of random distribution and no sorting. Therefore, on the basis of the laboratory tests with the coarse grained soil, the HHC-Granular model, which could simulate the no sorting and random distribution of different size particles in the coarse-grained soil, was developed by use of cellular automata method. Meanwhile, the triaxial numerical simulation experiments of coarse grained soil were finished with the different composition and structure soil, and the variation of shear strength was discussed. The results showed that the internal friction angle was likely to reduce with the increasing of gravel contents in the coarse-grained soil, but the mean internal friction angle significantly increased with the increment of gravel contents. It indicated that the gravel contents of shear bands were the major factor affecting the shear strength.

scholarly journals Experimental Research on the Mechanical Behavior of Lime-Treated Soil under Different Loading Rates

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Yue Qiang ◽  
Yulong Chen
Keyword(s):  
Shear Strength ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Mechanical Behavior ◽  
Loading Rate ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Treated Soil ◽  
Loading Rates ◽  
Lime Content

In order to study the mechanical behavior of lime-treated soil under different loading rates, a series of monotonous three-axial compression tests are carried out under different lime contents, different loading rates, and different curing periods. The test results indicate that the lime content can significantly improve the mechanical behaviors of soil, such as shear strength and elastic modulus. On the other hand, three-axial compression test of soil is carried out under the loading rate ranging from 0.1%/min to 8%/min. Experimental results indicate that the mechanical behavior of lime-treated soil is sensitive to loading rate. Besides, the corresponding relationship between internal friction angle, cohesion, lime content, and loading rate is discussed. The results indicate that the loading rate almost has no influence on internal friction angle but significant influence on lime content. Cohesion is affected by lime content and loading rate. Shear strength, elastic modulus, and cohesion all increase with the increase of loading rate. Longer curing period is associated with greater parameter value. Shear strength, elastic modulus, and internal friction angle all firstly increase and then decrease when lime content increases, which all reach the maximum at 6%.

Study on the Granular Shear Strength Parameters of Dumping Site

2012 ◽  
Vol 256-259 ◽  
pp. 358-361
Author(s):  
Xiang Yun Kong ◽  
Guang Jin Wang ◽  
Xiao Chao Zhou
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Dumping Site ◽  
Size Grading

Apparent particle size grading is the important characteristic of super-high bench dumping site, and the critical factors with the impact of its stability and disaster prevention are the fragmentation distribution and shear strength parameters of granular. With the copper mine dumping site which had the feature of apparent particle size grading, the thesis carried out the study of on-site particle size investigation and indoor laboratory. The particle-size distribution law with the changing of dumping-site height was analyzed and quantitative relationship between the fragmentation distribution and shear strength parameters of granular was discussed. The research results indicated that coarse-grain contents and maximum grain size were increased significantly according to the decreasing of dumping-site height, which showed that the dumping-site had the feature of apparent particle size grading. The coarse particle content in the grain size composition and internal friction angle φ of shear strength parameters increased with the obvious increment of the distribution value B. The relationship between distribution value B and the internal friction angle φ could be expressed by exponential function curve.

Experimental Study of the Shear Strength of Cobalt-Rich Crusts

2013 ◽  
Vol 419 ◽  
pp. 576-580 ◽  
Author(s):  
Hong Yun Wu ◽  
Zheng Chen
Keyword(s):  
Experimental Study ◽  
Shear Strength ◽  
Internal Friction ◽  
Empirical Formula ◽  
Laboratory Testing ◽  
Friction Angle ◽  
Strength Test ◽  
Strength Parameter ◽  
Shearing Strength

The shear strength parameter of cobalt-rich crusts can be used to design cobalt-rich crusts mining head. The shearing test of cobalt-rich crusts sample was done with different angle shearing testing apparatus.Firstly, the cobalt-rich crusts sample with the size of 50mmx50mmx50mm cube was clamped in the variable angle plate.Secondly, the sample ware loaded till to be damaged. Lastly,the damaged load were recorded at the degree of 50, 60 and 70 to establish their shearing strength and normal stress empirical formula.According to the testing result, its cohesion and internal friction angle parameters are respectively 0.275MPa and 54.43 degree. Restricted by the number of samples and limited by laboratory testing,in-situ shearing strength test should be carried out to improve the proposed empirical formula.

scholarly journals Experimental Studies of Scale Effect on the Shear Strength of Coarse-Grained Soil

2022 ◽  
Vol 12 (1) ◽  
pp. 447
Author(s):  
Shuya Li ◽  
Tiancheng Wang ◽  
Hao Wang ◽  
Mingjie Jiang ◽  
Jungao Zhu
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Internal Friction ◽  
Scale Effect ◽  
Friction Angle ◽  
Coarse Grained ◽  
Test Results ◽  
Maximum Particle Size ◽  
Maximum Particle ◽  
Coarse Grained Soil

Shear strength is an essential index for the evaluation of soil stability. Test results of the shear strength of scaled coarse-grained soil (CGS for short) are usually not able to accurately reflect the actual properties and behaviors of in situ CGS due to the scale effect. Therefore, this study focuses on the influence of the scale effect on the shear strength of scaled CGS, which has an important theoretical significance and application for the strength estimation of CGS in high earth-rock dam engineering. According to previous studies, the main cause of the scale effect for scaled CGS is the variation of the gradation structure as well as the maximum particle size (dmax), in which the gradation structure as a characteristic parameter can be expressed by the gradation area (S). A total of 24 groups of test soil samples with different gradations were designed by changing the maximum particle size dmax and gradation area S. Direct shear tests were conducted in this study to quantitatively explore the effect of the gradation structure and the maximum particle size on the shear strength of CGS. Test results suggest that the shear strength indexes (i.e., the cohesion and internal friction angle) of CGS present an increasing trend with the improvement of the maximum particle size dmax, and thus a logarithmic function relationship among c, φ, and dmax is presented. Both cohesion (c) and internal friction angle (φ) are negatively related to the gradation area (S) in most cases. As a result, an empirical relationship between c, φ, and S is established based on the test results. Furthermore, a new prediction model of shear strength of CGS considering the scale effect is proposed, and the accuracy of this model is verified through the test results provided by relevant literature. Finally, the applicability of this model to different types of CGS is discussed.

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