Deformation and strength properties of completely decomposed granite in a fault zone

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Shaohua Du ◽  
Diyuan Li ◽  
Chunshun Zhang ◽  
Dawei Mao ◽  
Bo Ruan
Keyword(s):  
Fault Zone ◽  
Strength Properties ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

Shear strength and dilative characteristics of an unsaturated compacted completely decomposed granite soil

2010 ◽  
Vol 47 (10) ◽  
pp. 1112-1126 ◽  
Author(s):  
Md. Akhtar Hossain ◽  
Jian-Hua Yin
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Matric Suction ◽  
Water Retention Curve ◽  
Direct Shear ◽  
Normal Stresses ◽  
Soil Water Retention Curve ◽  
Strength Data ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

Shear strength and dilative characteristics of a re-compacted completely decomposed granite (CDG) soil are studied by performing a series of single-stage consolidated drained direct shear tests under different matric suctions and net normal stresses. The axis-translation technique is applied to control the pore-water and pore-air pressures. A soil-water retention curve (SWRC) is obtained for the CDG soil from the equilibrium water content corresponding to each applied matric suction value for zero net normal stress using a modified direct shear apparatus. Shear strength increases with matric suction and net normal stress, and the failure envelope is observed to be linear. The apparent angle of internal friction and cohesion intercept increase with matric suction. A greater dilation angle is found at higher suctions with lower net normal stresses, while lower or zero dilation angles are observed under higher net normal stresses with lower suctions, also at a saturated condition. Experimental shear strength data are compared with the analytical shear strength results obtained from a previously modified model considering the SWRC, effective shear strength parameters, and analytical dilation angles. The experimental shear strength data are slightly higher than the analytical results under higher net normal stresses in a higher suction range.

Thermodynamic-based cross-scale model for structural soil with emphasis on bond dissolution

2021 ◽  
Author(s):  
Wei Zhang ◽  
Jia-qiang Zou ◽  
Kang Bian ◽  
Yang Wu
Keyword(s):  
Constitutive Model ◽  
Bond Strength ◽  
Scale Model ◽  
Triaxial Tests ◽  
Natural Soil ◽  
Engineering Practice ◽  
Compression Tests ◽  
Strength Deterioration ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

The immersion weakening effect of natural soil has always been a difficult problem encountered in geotechnical engineering practice. The bond dissolution is a common cause of soil strength deterioration, which remains not well understood yet. In this study, a thermodynamic-based constitutive model of structural soils based on the α model is first established, considering the bond strength by modifying the yield surface size and gradually reducing the bond strength with the development of plastic strain. Furthermore, by taking the meso-mechanisms of bond dissolution into account, the evolution rule of the free energy during the bond dissolution process is derived based on a homogenization approach, and a thermodynamic-based constitutive model of structural soil with bond dissolution is thereafter developed. By comparing with the results of one-dimensional compression tests and conventional triaxial tests, the model is verified to be capable of reflecting the gradual destructuration process of soil while loading. The comparison with triaxial test results of completely decomposed granite after different immersion durations and parametric studies show that based on the cross-scale energy equivalence, the model can well reflect the strength deterioration characteristics of completely decomposed granite with bond dissolution mechanisms at the mesoscale fully considered.

scholarly journals Effects of inclusion of granulated rubber tires on the mechanical behaviour of a compressive sand

2020 ◽  
Vol 57 (5) ◽  
pp. 763-769 ◽  
Author(s):  
W. Li ◽  
C.Y. Kwok ◽  
K. Senetakis
Keyword(s):  
Particle Size ◽  
Shear Strength ◽  
Mechanical Behaviour ◽  
Size Distributions ◽  
Particle Size Distributions ◽  
Rubber Content ◽  
Filling Materials ◽  
Rubber Particles ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

Drained triaxial shearing tests were performed on a well-graded compressive sand (completely decomposed granite, CDG) and its mixtures with granulated rubber tires to investigate the effects of rubber size and content on their mechanical behaviour. Three sizes of rubber particles, GR1, GR2, and GR3, were used with size ratios to CDG (D50,rubber : D50,CDG) of 0.9, 3.5, and 7.2, respectively, and the rubber content ranged from 0% to 30%. The results show that for CDG–GR1 mixtures, the strength decreases with increasing rubber content, while for CDG–GR2 and CDG–GR3 mixtures, the strength decreases only at 10% rubber content and then increases markedly with increasing rubber content. The increase of strength is mainly because the inclusion of large rubber particles widens the particle size distributions of the mixtures, resulting in denser packings. The denser packings also lead to a decrease in compressibility. At larger size ratio and higher rubber content, the CDG–rubber mixtures show higher shear strength and lower compressibility than pure CDG, which indicates the CDG–rubber mixtures are very suitable to be used as filling materials.

Mechanical behavior of intact completely decomposed granite soils along multi-stage loading–unloading path

2019 ◽  
Vol 260 ◽  
pp. 105242 ◽  
Author(s):  
Y.R. Zhao ◽  
H.Q. Yang ◽  
L.P. Huang ◽  
R. Chen ◽  
X.S. Chen ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Multi Stage ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

scholarly journals Bond Yield Characteristics of Undisturbed Completely Decomposed Granite

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Pan Liu ◽  
Xiaowen Zhou ◽  
Yongbin He
Keyword(s):  
Yield Point ◽  
Significant Influence ◽  
Southern China ◽  
Axial Strain ◽  
Critical Value ◽  
Consolidation Pressure ◽  
Tangential Stiffness ◽  
Bond Yield ◽  
Decomposed Granite ◽  
Completely Decomposed Granite

To investigate the bond yield characteristics of undisturbed completely decomposed granite (CDG) which is widely distributed in Southern China, a series of conventional drained tests were conducted. From the test data, some insights are obtained as follows: for undisturbed CDG soils, the bond yield point during shearing could be identified on the curve of the normalized tangential stiffnessEtan/p′versus axial strain on log-log scale. The consolidation pressureP0′has a significant influence on the bond yield characteristics of undisturbed CDG during shearing, the bonds inside undisturbed CDG tend to be damaged relatively more seriously asP0′is higher, accordingly the initial normalized stiffnessEitan/p′will be smaller at the beginning of the shearing process, and the axial strain at the bond yield point will also be smaller. Once consolidation pressureP0′excesses a critical value such as 475 kPa for this studied CDG, the bonds inside soil will be damaged totally at the consolidation compression stage. In this case, there will be no bond yield occurring during shearing and theEtan/p′-εacurves will coincide with the ones of reconstituted CDG soil. For reconstituted soils, no bond yielding was observed during shearing; theEtan/p′-εacurves are tightly consistent with no dependence of the value ofP0′.

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