scholarly journals Shear Behavior of Frozen Rock-Soil Mixture

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Changqing Qi ◽  
Liuyang Li ◽  
Jihong Wei ◽  
Jin Liu
Keyword(s):  
Shear Strength ◽  
Shear Test ◽  
Vertical Direction ◽  
Shear Behavior ◽  
Initial Water Content ◽  
Peak Shear Strength ◽  
Initial Water ◽  
Soil Mixture ◽  
Shear Process ◽  
Ice Content

Mechanical behavior of frozen rock-soil mixture was investigated through direct shear test based on remolded specimens. The peak shear strength of rock-soil mixture increases greatly when it is fully frozen. The shear process goes through four stages including compaction, elastic deformation, plastic yield, and failure. The specimen has slight compaction in vertical direction at the beginning of shear test; then it changes to dilatancy. The temperature and ice content have vital important effect on the shear behavior of frozen rock-soil mixture. Results indicated that the peak shear strength of rock-soil mixture increases with temperature decreasing when temperature ranges from −1°C to −16°C. But the curve has clear inflexion at −5°C. When temperature is higher than this degree, the peak shear strength increases sharply with temperature decreasing. Otherwise, the rise of the peak shear strength with the decrease of temperature becomes gentle. The shear strength of rock-soil mixture goes up first and then down with ice content increasing at −5°C for samples with initial water contents varying from 9% to 14%. The shear strength reaches its peak value at initial water content ranging between 10% and 12% by weight.

scholarly journals Shear strength characteristics of Jerash expansive soil

2021 ◽  
Vol 3 (2) ◽  
pp. 74-80
Author(s):  
Talal Masoud
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Direct Shear Test ◽  
Shear Test ◽  
Expansive Soil ◽  
Content Increase ◽  
Direct Shear ◽  
Initial Water ◽  
Angle Of Internal Friction

The results of the direct shear test on Jerash expansive soil show the effect of the initial water content on the cohesion (c) and on the angel of internal friction ( ) [shear strength parameters].it show that, as the initial water increase, the cohesion (c) of Jerash expansive soil also increase up to the shrinkage limit, after that increase of water even small amount, decrease the cohesion of the soil. On the other hand, the results of direct shear test show also  that as the water content increase, the angle of internal friction ( )remain unchanged up to shrinkage limit , any increase of water cause a large decrease on the angle of internal friction of Jerash expansive soil.

The Influence of Dehumidifying Condition on Expansive Soil Engineering Properties

2012 ◽  
Vol 594-597 ◽  
pp. 487-492
Author(s):  
Xiong Wei Li ◽  
Ai Jun Wang ◽  
Guo Zhong Dai
Keyword(s):  
Shear Strength ◽  
Relative Humidity ◽  
Water Content ◽  
Expansive Soil ◽  
Expansion Ratio ◽  
Soil Samples ◽  
Engineering Properties ◽  
Drying Rate ◽  
Initial Water Content ◽  
Initial Water

The expansive soil behaviour of expansive deformation and shear strength is deeply influenced by humidity condition. Different soil drying rate was set with constant temperature and different relative humidity. When saturated soil samples was dried to the different predetermined water content, the expansion ratio test with the upper load was made. It is shown that in the condition of high relative humidity, the expansion ratio is high. The smaller initial water content and upper load may lead to a larger swelling deformation. When soil samples with different initial water content was fully expanded, the consolidated direct shear tests were made. It is shown that the smaller drying rate leads to the greater shear strength after full expansion. What’s more, the upper load may improve the soil shear strength.

scholarly journals Numerical Shear Tests on the Scale Effect of Rock Joints under CNL and CND Conditions

2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Xige Liu ◽  
Wancheng Zhu ◽  
Lankun Li
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Scale Effect ◽  
Shear Behavior ◽  
Shear Displacement ◽  
Rock Joints ◽  
Peak Shear Strength ◽  
Normal Stresses ◽  
Shear Tests ◽  
Joint Length

The scale effect of rock joint shear behavior is an important subject in the field of rock mechanics. There is yet a lack of consensus regarding whether the shear strength of rock joints increases, decreases, or remains unchanged as the joint size increases. To explore this issue, a series of repeated and enlarged numerical joint models were established in this study using the particle flow code (PFC2D). The microparameters were calibrated by uniaxial compression tests and shear tests on the concrete material under the constant normal loading (CNL) condition. Three different normal stresses were adopted in numerical shear tests with joint specimen lengths ranging from 100 mm to 800 mm. In addition to the commonly used CNL, the constant normal displacement (CND) condition was established for the purposes of this study; the CND can be considered an extreme case of the constant normal stiffness (CNS) condition. The shear stress-shear displacement curves changed from brittle failure to ductile failure alongside a gradual decrease in peak shear strength as joint length increased. That is, an overall negative scale effect was observed. Positive scale effect or no scale effect is also possible within a limited joint length range. A positive correlation was also observed between the peak shear displacement and joint length, and a negative correlation between shear stiffness and joint length. These above statements are applicable to both repeated and enlarged joints under either CNL or CND conditions. When the normal stress is sufficiently high and shear dilatancy displacement is very small, the shear behavior of rock joints under CNL and CND conditions seems to be consistent. However, for shear tests under low initial normal stress, the peak shear strength achieved under the CND condition is much higher than that under the CNL condition, as the normal stresses of enlarged joints increase to greater extent than the repeated ones during shearing.

Application of acoustic emission for monitoring shear behavior of bonded concrete–rock joints under direct shear test

2012 ◽  
Vol 39 (8) ◽  
pp. 887-896 ◽  
Author(s):  
Z.A. Moradian ◽  
G. Ballivy ◽  
P. Rivard
Keyword(s):  
Acoustic Emission ◽  
Shear Strength ◽  
Normal Load ◽  
Adhesive Bond ◽  
Shear Behavior ◽  
Displacement Rate ◽  
Bond Breaking ◽  
Bonded Joints ◽  
Direct Shear ◽  
Shear Process

Studying shear behavior and failure mechanism of concrete–rock interfaces between concrete structures and rock mass is highly important. To this end, laboratory direct shear tests were conducted on several bonded interfaces. The effect of normal stress, displacement rate, and bonding percentage on shear behavior of bonded joints were also evaluated. The results showed that the adhesive bond between concrete and rock has the most important effect on shear mechanism of concrete–rock interfaces. When the normal load is low, the asperities do not contribute in shear process, so the shear strength of the joints is governed by adhesive bond. The only contribution of the asperities is that they show a small peak after bond breaking peak. When the normal load is high, the asperities break simultaneously with adhesive bond and they show their contribution in the whole shear process. In a constant normal load, by decreasing bonding percentage, the brittle failure of the bonded joints is changed into softening failure because of less contribution of the adhesive bond and more contribution of the rough asperities in joint failure. Acoustic emission (AE) monitoring of bonded joints showed that for all different tested samples under various loading conditions, there has been no or very few AE activities before adhesive bond breaking point, indicating that other parameters (roughness, normal load, displacement rate) are impressed by adhesive bond and maximum shear strength is determined by this parameter.

scholarly journals PENGARUH KADAR AIR AWAL KAYU JATI DAN SUHU CURING PEREKAT PADA KEKUATAN GESER SAMBUNGAN KAYU JATI (TECTONA GRANDIS) SECARA PEREKATAN

2014 ◽  
Vol 4 (2) ◽  
Author(s):  
Sugiman Sugiman ◽  
Abdul Hayyi Nu’man ◽  
Emmy Dyah Sulistyowati
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Tectona Grandis ◽  
Curing Temperature ◽  
Initial Water Content ◽  
Fick’S Law ◽  
Initial Water ◽  
Fick's Law ◽  
Structural Applications ◽  
Teak Wood

Adhesively wood-wood bonded joint has been widely used in structural applications, however because wood is a hygroscopic material that absorbed water from environment, hence the absorbed water affects the joints performance. The objective of the paper is to investigate water absorbtion and desorbtion behaviour and the combined effect of absorbed water into the wood before being bonded and adhesive curing temperature on the shear strength of teak wood joints. The initial water content in the wood was 0%, 37%, and 54%, while the curing temperature was a  room temperature for 24 hours, 50°C for 6 hours, and 100°C for 3 hours. The water absorbtion behaviour of teak wood deviate from the Fick's law, however the desorbtion tends to follow the Fick's law. Moreover the rate of absorbtion is higher than the rate of desorbtion. At the same curing temperature, the increase of water content decreases the shear strength of the joints; however the decrease was compensated by increasing the curing temperature. Curing at a high temperature (100 oC) improves the joints strength in all moisture content studied and the failure of the joints occurs at the wood.

scholarly journals Shear Characteristics and Strength Criterion of Frozen Joints under Different Opening Degrees

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Shiwei Shen ◽  
Lin Gan ◽  
Chang Liu ◽  
Shulin Dai
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Normal Stress ◽  
Strain Curve ◽  
Integral Form ◽  
Strength Criterion ◽  
Joint Surface ◽  
Peak Shear Strength ◽  
Shear Strength Criterion ◽  
Shear Process

Samples of rock coupling joints were collected from the Jiangluling Tunnel of the G214 line in Qinghai province. Models with surface topographies similar to these joints were manually created. Freezing shear tests under different normal stress conditions were conducted to study the shear mechanical properties of these models. On this basis, the integral form of the peak shear strength criterion of frozen joints was proposed. Results show that the shear process of the ice layer can be divided into four stages, namely, initial deformation, continuously increasing shear stress, ice shearing, and residual shear. During the continuously increasing shear stress stage, the stress-strain curve is concave, and elastic deformation is not evident. Furthermore, the increase rate of shear stress generally rises as normal stress intensifies. In the ice shearing stage, shear stress does not decrease instantaneously, but plastic deformation is now detectable. When the opening degree is greater than the undulation difference of the joint surface under the action of all levels of normal stress, the shear stress in the ice sharply increases and drops due to local failure and reicing. Then, evident difference between the shear processes under freezing and normal temperature conditions was then obtained. On this basis, the failure forms of joint surfaces, theory of ice adhesion strength under different opening degrees and morphologies, and the shear failure forms of frozen joints under different conditions were considered. The integral form of the peak shear strength criterion of frozen joints was proposed. These results can lay a theoretical foundation for the stability analysis of rock mass engineering in permafrost areas.

Influence of initial water content on unsaturated shear strength of compacted GaoMiaoZi (GMZ) bentonite

2021 ◽  
Vol 58 (1) ◽  
pp. 142-146
Author(s):  
N.F. Zhao ◽  
W.M. Ye ◽  
Q. Wang ◽  
B. Chen ◽  
Y.-J. Cui
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Critical State ◽  
Initial Water Content ◽  
Gmz Bentonite ◽  
Test Results ◽  
Loading Test ◽  
Initial Water ◽  
State Stress ◽  
Water Contents

This paper presents an experimental study on the influence of initial water content on unsaturated shear strength of compacted bentonite. Isotropic loading and triaxial shear tests were conducted on compacted GaoMiaoZi (GMZ) bentonite specimens with different initial water contents. Isotropic loading test and triaxial shear test results show that the compression index increases and yield stress decreases with increasing water content, while the swelling index stays constant. For normally consolidated and lightly overconsolidated bentonite, unsaturated shear strength can be described by the critical state line. For highly overconsolidated bentonite, unsaturated shear strength can be described by the Hvorslev surface. The critical state line and Hvorslev surface are found to be linear for the specimens with different water contents. The critical state stress ratio and the Hvorslev surface parameters are found to decrease with an increase in water content of the bentonite studied.

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