scholarly journals Effect of conglomeration gradation on loess shear strength with different water content

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110105
Author(s):  
Dequan Kong ◽  
Rong Wan ◽  
Chenkai Zhao ◽  
Jiumei Dai ◽  
Tijian Dong ◽  
...  
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Empirical Formulas ◽  
Factors Affecting ◽  
Direct Shear Tests ◽  
Loess Particles ◽  
The Difference

Particle gradation and water content are important factors affecting shear strength of soil. However, due to chemical cementation and molecular attraction, loess particles commonly stick together forming conglomerations. Till date, the superposition effect of water content and conglomeration gradation on loess shear strength has rarely been studied and undeniably requires further systematic explorations and development. In this study, loess samples were prepared with three conglomeration gradations and five water contents, and the direct shear tests were systematically performed. The shear strength of sample 1 (continuous conglomeration gradation) was found to be the best, followed by sample 2 (large size conglomerations), and sample 3 (small size conglomerations). The difference of samples’ shear strength decreased with increasing water content, and almost closed to zero when water content was 20%. The cohesion of samples first increased and then decreased with increasing water content, the maximum cohesion occurred at 10% water content. The internal friction angles decreased with increasing water content, and reached similar minimum values when the water content was 15%. The increased percentage values of cohesion and internal friction angle caused by conglomeration gradation are in the range of 33.2%–42.1% and 9.8%–32.5%, respectively. Finally, the empirical formulas for water content-cohesion and water content-internal friction angle of different conglomeration gradations samples were established, and the calculated values are in good agreement with test data. The effect of loess conglomeration gradation on shear strength decreased with increasing water content. When the water content was less than 15%, using a good conglomeration graduation could effectively improve loss shear strength.

Research on Shear Strength of Compacted Loess

2013 ◽  
Vol 448-453 ◽  
pp. 1284-1288 ◽  
Author(s):  
Juan Juan Wang ◽  
Jun Tao Deng ◽  
Song Lin Wu
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Dry Density ◽  
Dam Foundation ◽  
Direct Shear Tests ◽  
Strength Formula ◽  
Compacted Loess

Compacted loss widely used in the construction, such as embankment, dam, foundation backfill and other projects. Influenced by rainfall factors, the moisture content of compacted loess often vary so the shear strength will also changed. This paper studies the shear strength parameters of compacted loess through direct shear tests. In the dry density under the same conditions, the cohesion, internal friction angle of compacted loess decreases with the increase of water content. Summed cohesion and water content showed a quadratic parabola and internal friction angle and water content was also found quadratic parabola; further considering the effects of water content and dry density of compacted loess got shear strength formula. Shear strength formula.

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.

Study on the Effect of Water Content on Shearing Strength Parameters of Unsaturated Loess

2014 ◽  
Vol 638-640 ◽  
pp. 585-588 ◽  
Author(s):  
Si Zhong Qian
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Direct Shear ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Micro Particles ◽  
Shearing Strength ◽  
Unsaturated Loess

This paper experiments on typical Malan loess, performs consolidated quick direct shear tests under different water contents by conventional direct shear apparatus, then analyzes the effects of water content on shearing strength parameters, namely cohesion and internal friction angle. The results show that cohesion decreases linearly as the water content increasing, and the relation could be obtained by data fitting. However, internal friction angle keeps basically stable with the increase of water content. Finally, based on the force analysis for micro particles, the changing rules of cohesion and internal friction angle with water content were deeply explained.

Experimental Study on Structural Properties Influencing on Shear Strength of Soft Clay

2011 ◽  
Vol 243-249 ◽  
pp. 2487-2490
Author(s):  
Jiang Feng Wang ◽  
Yong Le Li ◽  
Yan Bin Gao ◽  
Yong Xiang Yang
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Shear Failure ◽  
Clayey Soil ◽  
Soft Clay ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Undisturbed Soil ◽  
Direct Shear Tests ◽  
Reconstituted Soil

The direct shear tests were conducted with undisturbed and reconstituted soft clay, then the structural influence on shear strength was studied, and the laws were got. No matter shear strength of slow shear or consolidated quick shear on undisturbed and reconstituted soil have not peak values, strength line of reconstituted soil is a slash, but the shear strength line of undisturbed soil is obviously a broken line. The internal friction angle of undisturbed and reconstituted soil is basically the same. There are good linear relationship between internal friction angle and plastic index of clayey soil. The amplitude of internal friction angle of reconstituted soil decreasing with plastic index increasing is less than that of undisturbed soil. From wf-lgp curve can be seen, with the increasing of vertical stress, water content of shear failure decrease gradually, and linear correlation of each curve is very good.

Stability Analysis of the Cutting Slope Considering the Influence of Water Content of Soil

2012 ◽  
Vol 204-208 ◽  
pp. 115-118 ◽  
Author(s):  
Qiang Ma ◽  
Heng Lin Xiao ◽  
Qi Zhi Hu ◽  
Li Hua Li
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Safety Factors ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Cutting Slope ◽  
Influence Of Water ◽  
The Stability

Based on the method of strength reduction, numerical simulations were carried out to analyze the stability of the cutting slope. The direct shear tests of slope soil samples with different water content were carried out, and the safety factors of stability of the cutting slope were investigated with different cohesions and internal friction angles. At last, displacements and safety factors of stability of the slope with drains and without drains were calculated, and the observations of displacement of the cutting slope in field were also carried out. The results show that: The water content of the slope soil has great effects on the strength parameters, the cohesion and the internal friction angle decrease with the increase of the water content, and the effect is more significant on the cohesion than that on the internal friction angle. The safety factor of stability for the slope increases with the increase of the strength parameters, hence it increases with the decrease of the water content. The section of the slope without drains in the field is unstable, while the section with drains maintains stable.

Influence of Freezing-Thawing on Shear Strength of Frozen Soil in Northeast China

2016 ◽  
Vol 835 ◽  
pp. 525-530 ◽  
Author(s):  
Rong Chen ◽  
Dong Zhe Li ◽  
Dong Xue Hao ◽  
Kai Li Wei
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Northeast China ◽  
Friction Angle ◽  
Frozen Soil ◽  
Internal Friction Angle ◽  
Silty Clay ◽  
Sharp Drop ◽  
Soil Cohesion

In order to study the influence of freezing-thawing cycles on shear strength of seasonal frozen soil in northeast China, silty clay, typical soil in Jilin region, was selected. 20 groups of specimens were carried out by quick shear tests considering soil water content and the number of freezing-thawing cycling. The test results indicate that soil cohesion presents the slight fluctuation with the increase of water content, and the maximum value reaches around the peak of liquid limit. Internal friction angle of soil shows the sharp drop and the extent changes between 40% - 60%. The soil cohesion gradually declines with the increase of the number of freeze-thawing cycling. Therefore, the effect of the first freezing-thawing cycle on soil cohesion is obvious, and cohesion gradually tend to be stable after 7 freezing-thawing cycles. The final value of cohesion is approximate a third to a half of the unfrozen soil. The internal friction angle of soil increases with the augment of cycling number of freezing-thawing, which is related to the water content. The higher water content will bring about the greater growth rate of friction angle.

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 Field Test Research on Red Clay Slope under Atmospheric Action

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Kaisheng Chen
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Red Clay ◽  
Failure Characteristics ◽  
Clay Slopes

By embedding water content sensors and pore water pressure sensors inside the red clay slope on-site in Guiyang, Guizhou, shear tests were performed on soil samples at different depths of the slope under different weather. The changes of water content, pore water pressure, and shear strength index of the slope inside the slope under the influence of the atmosphere were tracked and tested, and the failure characteristics and evolution of the red clay slope were analyzed. It is believed that the depth of influence of the atmosphere on red clay slopes is about 0.7 m, rainfall is the most direct climatic factor leading to the instability of red clay slopes, and the evaporation effect is an important prerequisite for the catastrophe of red clay slopes. The cohesion and internal friction angle of the slope soil have a good binary quadratic function relationship with the water content and density. The water content and density can be used to calculate the cohesion and internal friction angle. Failure characteristics of red clay slopes: the overall instability failure is less, mainly surface failure represented by gullies and weathering and spalling, and then gradually evolved into shallow instability failure represented by collapse and slump. The damage evolution law is as follows: splash corrosion and surface corrosion stage⟶ fracture development stage⟶ gully formation stage⟶ gully development through stage⟶ local collapse stage⟶ slope foot collapse stage.

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.

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