scholarly journals Mechanical Properties of Frozen Glacial Tills due to Short Periods of Thawing

2021 ◽  
Vol 9 ◽  
Author(s):  
Yanju Fu ◽  
Yao Jiang ◽  
Jiao Wang ◽  
Ziming Liu ◽  
Xingsheng Lu
Keyword(s):  
Shear Strength ◽  
Initial Phase ◽  
Peak Stress ◽  
Friction Angle ◽  
Initial Water ◽  
Direct Shear Tests ◽  
Warming Climate ◽  
Marked Decline ◽  
Glacial Tills ◽  
Water Contents

Due to the warming climate, glacier retreat has left massive glacial tills in steep gullies; ice in the soil is prone to change phase resulting in the decrease of the ice strength and bonding of soil particles; collapse of thawing tills can lead to debris flows with disastrous consequences for geotechnical infrastructures. To improve our understanding of the mechanics of thawing glacial tills, we conducted unconsolidated–undrained direct shear tests on glacial tills from Tianmo gully on the southeastern Tibetan Plateau. Control specimens were not subjected to freeze–thaw action. A total of 648 specimens with three different dry densities, three initial water contents, and 18 thawing times were tested. Peak shear strength, peak stress to displacement ratio (0.857), and cohesion were the highest in frozen specimens. After a thawing time of 0.25 h, there was a marked decline in shear strength; maximum friction was 2.58, which was far below the value of cohesive strength. For thawing times of 0.25–4 h, peak strength varied little with thawing time, but cohesion decreased and internal friction angle increased with increasing thawing time. Our results indicate that thawing of the solid ice in the till during the initial phase of till thawing is the key control of peak till strength; the effect of ice on cohesion is greater during the initial phase of thawing and in loose tills. Moreover, frequent sediment recharge of gullies may be explained by the decrease of cohesion with increasing thawing time caused by short-term destruction of ice bonding.

Influence of Water Contents on Shear Strength of Rammed Earth Wall of Earth-Building

2011 ◽  
Vol 382 ◽  
pp. 172-175
Author(s):  
Ren Wei Wu ◽  
Xing Qian Peng ◽  
Li Zhang
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
World Heritage Site ◽  
Rammed Earth ◽  
Compression Tests ◽  
Rammed Earth Wall ◽  
Influence Of Water ◽  
Water Contents

As the "Fujian earth-building" have been inscribed by UNESCO in 2008 as World Heritage Site, attentions of protection about the "Fujian earth-building" has getting more and more. This article takes samples of a rammed-earth wall from Yongding earth-buildings and determines the shear strength of the samples with different water content through triaxial compression tests. The influence on shear strength of water content of rammed-earth samples is analyzed. Test results show that the shear strength of rammed-earth has much to do with the water content of the soil, the greater the water content is，the smaller the shear strength is. With water content increasing, cohesion and internal friction angle of rammed-earth were decreases, and its changing trend is of marked characteristic of stage. When water contents of rammed-earth is under some value, its cohesion changes in small ranges; when water contents of rammed-earth is over the value, its cohesion decreases with water content increasing.

scholarly journals Improving Shear Strength Parameters of Sandy Soil using Enzyme-Mediated Calcite Precipitation Technique

2018 ◽  
Vol 20 (2) ◽  
pp. 91 ◽  
Author(s):  
Heriansyah Putra ◽  
Hideaki Yasuhara ◽  
Naoki Kinoshita ◽  
Erizal . ◽  
Tri Sudibyo
Keyword(s):  
Shear Strength ◽  
Sandy Soil ◽  
Friction Angle ◽  
Soil Improvement ◽  
Soil Mass ◽  
Shear Strength Parameters ◽  
Calcite Precipitation ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Potential Applications

Several methods have been established for their various potential applications as soil improvement technique, and recently the application of grouting technique using biological process have been proposed. This study discussed the applicability of enzyme-mediated calcite precipitation (EMCP) in improving the shear strength parameters of sandy soil.  In this study, soil specimens were prepared and treated with the grouting solutions composed of urea, calcium chloride, magnesium sulfate and enzyme of urease. Evolutions in the cohesion and internal friction angle of the improved soil were examined through the direct shear tests. The presence of the precipitated materials, comprising 4.1 percent of the soil mass of the treated sand, generated a cohesion of 53 kPa. However, contrary to the improvement of cohesion, the friction angle is relatively constant. It indicated that the application of the EMCP technique has no significant impact on the friction angle

scholarly journals Comparative Study between Silica Fume and Nano Silica Fume in Improving the Shear Strength and Collapsibility of Highly Gypseous Soil

2020 ◽  
Vol 27 (1) ◽  
pp. 72-78
Author(s):  
Ahmed Al-Obaidi ◽  
Marwa Al-Mukhtar ◽  
Omar Al-Dikhil ◽  
Saeed Hannona
Keyword(s):  
Shear Strength ◽  
Silica Fume ◽  
Friction Angle ◽  
Engineering Properties ◽  
Nano Silica ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Gypsum Content ◽  
Wet Condition ◽  
Gypseous Soil

Soils with highly gypsum content signify known as soils that exhibit collapsibility and sudden failure when being submerged to wetting. Many of the constructions built on this soil showed cracked and/or collapsed at some parts as these soils immersed or leached with water. The utilization of extremely fine materials, for example, Microscale or Nanoscale, is generally utilized these days. This research compared the use of Silica fume (SF) (micro material) and Nano Silica fume (NSF) (Nanomaterial) to explore the capability of these very fine materials to mend the shear strength and collapsibility properties of highly gypseous soils. The soil as Poorly Graded Sand (SP) was used, with a gypsum amount equal to 62%. A succession of direct shear tests and double odometer tests were carried on dry and submarined specimens of soil at various percentages of SF and NSF. The obtained results indicate that mixing the highly gypseous soils with SF or NSF improved the engineering properties of these soils, especially for the wet condition. The average increment in apparent cohesion when adding SF (5-20) percentage varies between (140-310) % in dry soil and (20-40) % in soaked soil. Same results obtained when mixing the gypseous soils with (1-5) % of NSF. Also, the Nanomaterial provided an improvement of the friction angle in dry and submerged cases respectively. Considering that, the SF gives adverse results upon the friction angle of the soil. The SF and the NSF both condensed the dangers of gypseous soil collapsibility. Consequently, the use of NSF can be assertively suggested to improve the engineering characteristics of highly gypseous soils when compared with SF, where only mixing of 3% of NSF gives the best results.

Research on Direct Shear Strength Characteristics of Mechanically Biologically Treated Waste

2021 ◽  
Author(s):  
Zhenying Zhang ◽  
Jiahe Zhang ◽  
Qiaona Wang ◽  
Min Wang ◽  
Chengyu Nie
Keyword(s):  
Shear Strength ◽  
Test Data ◽  
Peak Stress ◽  
Friction Angle ◽  
Treatment Method ◽  
Strength Characteristics ◽  
Direct Shear ◽  
Horizontal Shear ◽  
Stability Calculation ◽  
Shearing Rate

Abstract Mechanically biologically treated (MBT) waste has significant characteristics such as high stability and low moisture content, which can reduce water, soil, and gas pollution in subsequent treatments. This pre-treatment method is environmentally friendly and sustainable, and has become a popular research topic in the field of environmental geotechnical engineering. Using a direct shear test apparatus and five shearing rates (0.25, 1, 5, 10, and 20 mm/min), the shear strength characteristics of MBT waste at the Hangzhou Tianziling (HT) Landfill were studied. The results indicate: (1). With the increase in horizontal shear displacement, the shear stress of MBT waste gradually increases without a peak stress phenomenon, which is a displacement hardening curve; (2). The shear strength increased with an increase in the shearing displacement rate, and the sensitivity coefficient was 0.64–2.66. (3). The shear strength, shearing rate, and normal stress correlation model are established, and the model has a high degree of fit with the overall experimental data; (4). Cohesion (c), internal friction angle (φ), and the logarithm of the shearing rate are linear; (5). The range of c of MBT waste is 22.32–39.51 kPa, and φ is 64.24–.68.52°. Meanwhile, the test data are compared with the test data in the literature, and the shear characteristics of HT-MBT waste are discussed. The research results of this study can provide a reference for the stability calculation of MBT landfills.

Mechanical Properties of Interface Between Soil-Macadam Aggregate and Concrete Pile

2011 ◽  
Vol 368-373 ◽  
pp. 230-233 ◽  
Author(s):  
Shao Jun Li ◽  
Fan Zhen Meng ◽  
Jing Chen ◽  
Hong Min
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Safety Evaluation ◽  
Friction Angle ◽  
Reservoir Water ◽  
Reservoir Water Level ◽  
Direct Shear Tests ◽  
Concrete Pile ◽  
Shearing Strength ◽  
Reinforcement Design

The mechanical properties of interface between soil-macadam aggregate and anti-sliding concrete pile are very important for the reinforcement design and safety evaluation of accumulative landslide in the reservoir area of Three Gorges. Soil-macadam aggregate is a complex geomaterial whose properties are totally different with soil or rock. Based on a practical landslide suffering the influence of reservoir water level change and seasonal rainfall, a series of direct shear tests are conducted to investigate the interface mechanical properties between soil-macadam aggregate and concrete pile. Accordingly, the relationship between shear strength parameters and water contents and macadam ratios is presented. The change characteristics of mechanical properties of interface are discussed. The results indicate that shearing strength, inner friction angle and cohesion decrease with less water content. However, as the increment of macadam ratios, the cohesion will decrease gradually, but the shear strength and inner friction angle of interface decrease firstly and then increase after a critical value, the change trend obeys parabolic relation.

Experimental Study on Shear Behavior of Short-Fill-Age MSW

2010 ◽  
Vol 113-116 ◽  
pp. 479-483
Author(s):  
Li Sha Ma ◽  
Huan Li Wang ◽  
Wei Wang ◽  
Zheng Wen Zhang
Keyword(s):  
Shear Strength ◽  
Shear Failure ◽  
Friction Angle ◽  
Exponential Model ◽  
Hyperbolic Model ◽  
Displacement Curve ◽  
Shear Tests ◽  
Direct Shear Tests ◽  
Cohesion Force ◽  
Coulomb Criterion

Mechanical behavior of municipal solid waste (MSW) is important to geo-environment engineering, and it is necessary to properly understand it. Laboratory direct shear tests were conducted on MSW with 3 short fill ages, namely 1d, 4d and 7d. Three different densities were taken into accounted in each fill age. Experimental data show that MSW’s shear failure still satisfies the Mohr-Coulomb criterion. As to bigger density, shear strength of MSW increases within 1-7d fill age. When density becomes smaller, its shear strength increases within 1-4d fill age but decreases within 4-7d fill age. With fill-age developing, friction angle of MSW increase monotonously, but cohesion force of it first increases and then decreases. Experimented shear stress-displacement curve of MSW can not be well fitted by either hyperbolic model or exponential model. This experimental research is helpful for design and numerical simulation of corresponding MSW landfill.

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.

scholarly journals Effect of Polypropylene Fibers on the Shear Strength–Dilation Behavior of Compacted Lateritic Soils

2021 ◽  
Vol 13 (22) ◽  
pp. 12603
Author(s):  
Maitê Rocha Silveira ◽  
Sabrina Andrade Rocha ◽  
Natália de Souza Correia ◽  
Roger Augusto Rodrigues ◽  
Heraldo Luiz Giacheti ◽  
...  
Keyword(s):  
Shear Strength ◽  
Constitutive Models ◽  
Friction Angle ◽  
Polypropylene Fibers ◽  
Fiber Reinforced ◽  
Lateritic Soils ◽  
Reinforced Soils ◽  
Direct Shear Tests ◽  
Fibers Orientation ◽  
Soil Mix

The stress–dilatancy relationship for fiber-reinforced soils has been the focus of recent studies. This relationship can be used as a foundation for the development of constitutive models for fiber-reinforced soils. The present study aims to investigate the effect of recycled polypropylene fibers on the shear strength–dilation behavior of two lateritic soils using the stress–dilatancy relationship for direct shear tests. Results show that fibers improved the shear strength behavior of the composites, observed by increases in the friction angle. Fibers’ orientation at the sheared interface could be observed. The volumetric change during shearing was altered by the presence of fibers in both soils. Overall, results indicate that the stress–dilatancy relationship is affected by inclusions in the soil mix. Results can be used to implement constitutive modeling for fiber-reinforced soils.

scholarly journals Determination of the Effect of Soil Particle Size Distribution on the Shear Behavior of Sand

2021 ◽  
Vol 5 (2) ◽  
pp. 125
Author(s):  
Mohammad Afrazi ◽  
Mahmoud Yazdani
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Direct Shear Test ◽  
Shear Test ◽  
Friction Angle ◽  
Particle Sizes ◽  
Direct Shear ◽  
Shear Tests ◽  
Direct Shear Tests

Many geotechnical problems require the determination of soil engineering properties such as shear strength. Therefore, the determination of the reliable values for this parameter is essential. For this purpose, the direct shear test, as one of the oldest tests to examine the shear strength of soils, is the most common way in laboratories to determine the shear parameters of soil. There are far too many variables that influence the results of a direct shear test. In this paper, a series of 10 × 10 cm direct shear tests were carried out on four different poorly graded sands with different particle size distributions to determine their shear behaviors. Four different poorly graded sands with a different median diameter or medium value of particle size distribution (D50) (0.2, 0.53, 1.3, and 2.3 mm) has been selected, and about 40 direct shear tests were conducted. It was concluded that a soil’s friction angle is affected by coarse-grained material. Accordingly, sandy soils with bigger particle sizes record a higher friction angle than soils containing small particles. The investigations also showed that sand with bigger particle sizes has a higher dilation angle. In addition, a non-linear regression analysis was performed to establish the exact relationship between the friction angle of the soil and the characteristics of the soil particles. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium provided the original work is properly cited.

Influence of Density on the Hydraulic and Mechanical Properties of Sands

2014 ◽  
Vol 580-583 ◽  
pp. 659-664
Author(s):  
Osvaldo de Freitas Neto ◽  
Olavo Francisco dos Santos Jr. ◽  
Ricardo Nascimento Flores Severo
Keyword(s):  
Shear Strength ◽  
Hydraulic Conductivity ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Coarse Fraction ◽  
Direct Shear ◽  
Direct Shear Tests ◽  
Strength Tests ◽  
Constant Head ◽  
Direct Shear Testing

This article aims at assessing the influence of relative density on the hydraulic conductivity and shear strength of two sands, denominated S01 and S02, derived from different regions and formation processes. S01 is wind-blown and S2 alluvial. The results of characterization and hydraulic conductivity in constant head tests were presented for both samples. The results of direct shear tests with sand S01 prepared with 5 different void ratios were also presented, for a vertical stress of 100kPa. The S02 sample was prepared with 4 different void ratios and these underwent direct shear testing with vertical stresses of 25kPa and 150kPa. This sample was prepared with the maximum and minimum void ratio and submitted to strength tests at CD triaxial compression with confining stresses of 50kPa, 100kPa and 200kPa. Results showed that even with different grain sizes, and under different density conditions, there were no significant variations in the permeability of the materials. With respect to shear strength, sand S01 obtained higher angle of friction values than sand S02, even though the latter had a higher percent coarse fraction. Sand S02 was relatively similar in terms of friction angle values obtained in direct shear and triaxial compression strength tests.

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