scholarly journals Effect of Prior Cyclic Loading on Triaxial Compression Strength of Sliding Zone Soil of the Huangtupo Landslide

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Qiong Chen ◽  
Deshan Cui ◽  
Yu Chen ◽  
Xianyu Tao ◽  
Wei Xiang
Keyword(s):  
Cyclic Loading ◽  
Loading Condition ◽  
Stress Ratio ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Cycle Period ◽  
Confining Pressures ◽  
Number Of Cycles ◽  
Logarithmic Relation ◽  
Sliding Zone

Earthquakes or cyclic loadings cause significant changes in the strength characteristics of soil. These changes, especially for sliding zone soil, can lead to catastrophic landslides. Taking into account this characteristic, this paper investigates the effects of prior cyclic loading on the consolidated undrained triaxial compression strength of sliding zone soil with the KTL triaxial automated system. Our experimental results indicate that the prior cyclic loading has a significant effect on the strength behaviour of saturated sliding zone soil. Under different confining pressures, cycle periods, and number of cycles, the samples exhibit the characteristics of strain-hardening. Deviatoric stress under cyclic loading condition is smaller than that with monotonic loading condition under different confining pressures, cycle periods, and number of cycles. As the confining pressure and cycle period increase, the failure stress ratio decreases. The axial strain exhibits a steep rise first and then stays stable under a cycle period of 90 s, while the axial strain shows a linear increase with an increase in the number of cycles under a cycle period of 10 s under confining pressures of 100 kPa and 400 kPa, respectively. The logarithmic relation correlates well with the failure stress ratio in the cyclic loading tests, which preliminary validates the applicability of logarithmic relation for sliding zone soil influenced by prior cyclic loading, providing a theoretical basis and guidance for the further understanding of strength characteristics of sliding zone soil.

scholarly journals Energy Evolution Law of Marble Failure Process Under Different Confining Pressures Based on Particle Discrete Element Method

2021 ◽  
Vol 8 ◽  
Author(s):  
Yan-Shuang Yang ◽  
Wei Cheng ◽  
Zhan-Rong Zhang ◽  
Hao-Yuan Tian ◽  
Kai-Yue Li ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Failure Process ◽  
Rock Failure ◽  
Biaxial Compression ◽  
Energy Evolution ◽  
Confining Pressures ◽  
Energy Dissipated

The energy dissipation usually occurs during rock failure, which can demonstrate the meso failure process of rock in a relatively accurate way. Based on the results of conventional triaxial compression experiments on the Jinping marble, a numerical biaxial compression model was established by PFC2D to observe the development of the micro-cracks and energy evolution during the test, and then the laws of crack propagation, energy dissipation and damage evolution were analyzed. The numerical simulation results indicate that both the crack number and the total energy dissipated during the loading process increase with confining pressures, which is basically consistent with the experiment results. Two damage variables were presented in terms of the density from other researchers’ results and energy dissipation from numerical simulation, respectively. The energy-based damage variable varies with axial strain in the shape of “S,” and approaches one more closely than that based on density at the final failure period. The research in the rock failure from the perspective of energy may further understand the mechanical behavior of rocks.

Experimental Observation on the Uniaxial Cyclic Deformation Behaviour of TA16 Titanium Alloy

2011 ◽  
Vol 415-417 ◽  
pp. 2318-2321 ◽  
Author(s):  
Qian Hua Kan ◽  
Wen Yi Yan ◽  
Guo Zheng Kang ◽  
Su Juan Guo
Keyword(s):  
Titanium Alloy ◽  
Cyclic Loading ◽  
Cyclic Deformation ◽  
Room Temperature ◽  
Stress Ratio ◽  
Stress Amplitude ◽  
Deformation Behaviour ◽  
Ratcheting Strain ◽  
Number Of Cycles ◽  
Stable Material

The cyclic deformation including the ratcheting of TA16 titanium alloy was investigated experimentally at room temperature. Experimental results under symmetrical strain-controlled cyclic loading with various strain amplitudes show that the responded stress amplitude keeps almost unchanged with the increasing number of cycles. It is concluded that TA16 titanium alloy can be regarded as a cyclic stable material. Remarkable ratcheting was also observed under asymmetrical stress-controlled cyclic loading, i.e., ratcheting strain increases with the increasing number of cycles. The ratcheting strain strongly depends on the stress level and increases with the increase of applied mean stress, stress amplitude and stress ratio. These findings are useful to reasonably model the cyclic deformation of TA16 titanium alloy.

scholarly journals The Effect of Confining Pressure on the Mechanical Properties of Sand–Ice Materials

1973 ◽  
Vol 12 (66) ◽  
pp. 469-481 ◽  
Author(s):  
Bernard D. Alkire ◽  
Orlando B. Andersland
Keyword(s):  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Silica Sand ◽  
Creep Tests ◽  
Ice Volume ◽  
Coulomb Failure ◽  
Confining Pressures ◽  
Sand Material ◽  
Cylindrical Samples

Cylindrical samples containing 0.59 mm to 0.84 mm diameter silica sand at about 97% and 55% ice saturation (the ratio of ice volume to sand pore volume) were tested at a temperature of −12° C in triaxial compression. Both constant axial strain-rate tests and step-stress creep tests provide information on the influence of confining pressure on the shear strength and creep behavior of the sand–ice material. Changes in the degree of ice saturation help show the influence of the ice matrix versus the sand material on the mechanical behavior. Data are discussed in terms of the Mohr–Coulomb failure law and creep theories. It is shown that the cohesive component of strength depends on response of the ice matrix, whereas the frictional component of strength responds in a manner very similar to unfrozen sand tested at high confining pressures. Experimental data show that creep rates decrease exponentially and creep strength increases with an increase in confining pressure.

Strain degradation of saturated clay under cyclic loading

2001 ◽  
Vol 38 (1) ◽  
pp. 208-212 ◽  
Author(s):  
Jian Zhou ◽  
Xiaonan Gong
Keyword(s):  
Mathematical Model ◽  
Cyclic Loading ◽  
Stress Ratio ◽  
Axial Strain ◽  
Influence Factors ◽  
Cyclic Stress ◽  
Point Of View ◽  
Triaxial Tests ◽  
Cyclic Stress Ratio ◽  
Saturated Clay

Soil degradation is studied from the point of view of cyclic axial strain through stress-controlled triaxial tests on Hangzhou normally consolidated clay. Different influence factors on strain, such as cyclic stress ratio, overconsolidation ratio, and frequency, are studied. Degradation index is redefined according to the tests. A mathematical model for strain degradation is presented and verified.Key words: cyclic loading, saturated clay, strain degradation, mathematical model.

scholarly journals Effect of Cyclic Loading on the Lateral Behavior of Offshore Monopiles Using the Strain Wedge Model

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Keunju Kim ◽  
Boo Hyun Nam ◽  
Heejung Youn
Keyword(s):  
Cyclic Loading ◽  
Lateral Displacement ◽  
Triaxial Compression ◽  
Lateral Loads ◽  
Compression Tests ◽  
Initial Stiffness ◽  
Quartz Sands ◽  
Number Of Cycles ◽  
Lateral Behavior ◽  
Strain Wedge

This paper presents the effect of cyclic loading on the lateral behavior of monopiles in terms of load-displacement curves, deflection curves, andp-ycurves along the pile. A commercial software, Strain Wedge Model (SWM), was employed, simulating a 7.5 m in diameter and 60 m long steel monopile embedded into quartz sands. In order to account for the effect of cyclic loading, accumulated strains were calculated based on the results of drained cyclic triaxial compression tests, and the accumulated strains were combined with static strains representing input strains into the SWM. The input strains were estimated for different numbers of cycles ranging from 1 to 105and 3 different cyclic lateral loads (25%, 50%, and 75% of static capacity). The lateral displacement at pile head was found to increase with increasing number of cycles and increasing cyclic lateral loads. In order to model these deformations resulting from cyclic loading, the initial stiffness of thep-ycurves has to be significantly reduced.

scholarly journals Experimental Research into the Evolution of Permeability of Sandstone under Triaxial Compression

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5065
Author(s):  
Liming Zhang ◽  
Shengqun Jiang ◽  
Jin Yu
Keyword(s):  
Axial Strain ◽  
Triaxial Compression ◽  
Testing Machine ◽  
Volumetric Strain ◽  
Confining Pressure ◽  
Rate Of Change ◽  
Peak Strength ◽  
Sudden Increase ◽  
Seepage Pressure ◽  
Confining Pressures

Failure tests on sandstone specimens were conducted under different confining pressures and seepage pressures by using an MTS triaxial rock testing machine to elucidate the corresponding correlations of permeability and characteristic stress with confining pressure and pore pressure during deformation. The results indicate that permeability first decreases and presents two trends, i.e., a V-shaped increase and an S-shaped trend during the non-linear deformation stage. The greater the seepage pressure, the greater the initial permeability and the more obvious the V-shaped trend in the permeability. As the confining pressure was increased, the trend in the permeability gradually changed from V- to S-shaped. Compared with the case at a high confining pressure, the decrease of permeability occurred more quickly, the rate of change becomes greater, and the sudden increase observed in the permeability happened earlier under lower confining pressures. Within the range tested, confining pressure exerted a greater effect on the permeability than the seepage pressure. In comparison with the axial strain, volumetric strain better reflected changes in permeability during compaction and dilation of sandstone. The ratio of crack initiation stress to peak strength ranged from 0.37 to 0.50, while the ratio of dilation stress to peak strength changed from 0.58 to 0.72. Permeabilities calculated based on Darcy and non-Darcy flow changed within the same interval, while the change in permeability was different.

scholarly journals An Experimental Investigation of the Progressive Failure of Sandstone and Its Energy Evolution Characteristics

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Yan Chen ◽  
Baohua Guo
Keyword(s):  
Crack Propagation ◽  
Crack Closure ◽  
Progressive Failure ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Energy Evolution ◽  
Evolution Characteristics ◽  
Confining Pressures ◽  
The Relationship

In this research study, the progressive failure and energy evolution characteristics of sandstone samples with different sizes were explored under uniaxial and triaxial compression conditions. The characteristic stresses and strains were captured using the crack axial strain levels and dissipative energy. The results showed that, with the increase in the ratios of the height to diameter (H/D), the crack closure stresses increased, while the crack damage stresses decreased. However, the levels of both the crack closure stresses and crack damages were observed to increase with the H/D. With increase in the confining pressure, it was found that the crack closure and crack damage stresses increased, while their levels decreased. The strains of the crack closures, peak crack axial, and crack propagation were observed to decrease with the H/D, while the crack closure strain levels increased. Also, the crack propagation strains were observed to increase with the confining pressures, while the crack closure, peak crack axial, and crack closure strain levels decreased. The progress failure of the sandstone samples was also obtained based on the evolution characteristics of the dissipative energy. The relationship between the energy densities during each phase and the H/D was also analyzed. It was determined that, with the increasing of the H/D, the input, elastic, and dissipative energy densities displayed different evolution characteristics. Furthermore, with the increases in the characteristic stresses, the input and elastic energy densities were found to increase. The dissipative energy density displayed a slight increase with the increases in the peak strength, which resulted in variations with regard to the crack closures and crack damage stresses.

scholarly journals Experimental investigation on creep behavior of clastic rock

2020 ◽  
Vol 165 ◽  
pp. 03051
Author(s):  
Zhang Yu ◽  
Zhang Yan ◽  
Mei Song-hua
Keyword(s):  
Axial Strain ◽  
Triaxial Compression ◽  
Testing Machine ◽  
Creep Model ◽  
Test Results ◽  
Creep Failure ◽  
Creep Properties ◽  
Clastic Rock ◽  
Confining Pressures ◽  
The Relationship

Many deflected fault zones exist under the dam foundation Xiang-jiaba Hydropower Station in southwestern China. Clastic rock is the main medium with poor physical and mechanical properties. In or-der to study the creep properties of the clastic rock, triaxial compression creep experiments were carried out on a rock servo-controlling rheology testing machine. From the test results, it can be concluded that the clastic rock has obvious creep characteristics, and the time-dependent deformation is large. Based on the test results, the relationship between axial strain and time under different confining pressures is studied. The relationship between axial strain rates and deviatoric stress under different stress levels is also discussed in de-tail. Furthermore, the creep failure mechanism under different confining pressures is analyzed as well. Therefore, the creep law of the clastic rock specimen is gained. The relationship between the Burgers creep model and its parameters is obtained by fitting the creep curve with Burgers creep model. The result shows that Burgers model can accurately describe the creep properties of the clastic rock in Xiang-jiaba Hydro-power Project.

scholarly journals Study of statistical damage constitutive model of layered composite rock under triaxial compression

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Yong-Sheng Liu ◽  
Zhuan-Zhuan Qiu ◽  
Xue-Cai Zhan ◽  
Hui-Nan Liu ◽  
Hai-Nan Gong
Keyword(s):  
Constitutive Model ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Layered Composite ◽  
Model Parameters ◽  
Compression Tests ◽  
Fitting Method ◽  
Confining Pressures ◽  
Curve Fitting Method

Abstract The layered composite rock was subjected to triaxial compression tests under constant confining pressure and the stress–strain curves under different confining pressures were obtained. Based on the continuous damage theory and statistical strength theory, it is assumed that the strength of rock microelements obeys Weibull distribution by taking the defects such as random micro-cracks in the rock into account. The statistical constitutive model of layered composite rock with damage correction is established by taking the axial strain of rock as a random distribution variable of microelement strength. The model parameters were determined by the curve fitting method and referring to some test parameters. By comparing the experimental data and the constitutive model curve, the rationality and feasibility of the model are verified.

scholarly journals Fatigue and damage properties of frozen silty sand samples subjected to cyclic triaxial loading

2016 ◽  
Vol 53 (12) ◽  
pp. 1939-1951 ◽  
Author(s):  
Enlong Liu ◽  
Yuanming Lai ◽  
Mengke Liao ◽  
Xingyan Liu ◽  
Feng Hou
Keyword(s):  
Stress Ratio ◽  
Axial Strain ◽  
Volumetric Strain ◽  
Silty Sand ◽  
Triaxial Tests ◽  
Axial Stiffness ◽  
Cyclic Triaxial ◽  
Cycle Number ◽  
Number Of Cycles ◽  
Strain Method

Cyclic triaxial tests were conducted to explore the influences of dynamic axial loading on the dynamic features and fatigue of frozen silty sand, using an MTS-810 apparatus from Material Testing Systems (MTS). The temperature was −15 °C, and the cyclic axial loads with different amplitudes at 1.0 Hz were applied under confining pressures of 0.6, 1.4, and 6.0 MPa. The cyclic triaxial test results demonstrate that the residual axial strain of the frozen silty sand samples increases gradually during the initial cycles and then increases with increasing number of cycles at a constant speed until failure. The residual volumetric strain contracts during the initial loading cycles and then dilates until failure. Both the residual strain method and the residual volumetric strain method proposed here can be used to describe the degradation process in frozen silty sand samples subjected to cyclic loading. The dynamic axial stiffness of a frozen sample decreases rapidly in the initial cycles and then approaches a stable value with increasing cycle number. The initial damage increases when the stress ratio increases; the larger the stress ratio, the smaller the number of cycles at failure.

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