scholarly journals Effect of Initial Stress Conditions on Liquefaction of Sands: Experiments and an Interpretation

1983 ◽  
Vol 23 (1) ◽  
pp. 102-107 ◽  
Author(s):  
M. Ali Erguvanli ◽  
I. Kutay Özaydin
Keyword(s):  
Initial Stress ◽  
Stress Conditions

scholarly journals Experimental Study on the Fracture Behaviors Effect of Stress Conditions on the Fracture of Shale by Super-Critical Carbon Dioxide

2021 ◽  
Vol 9 ◽  
Author(s):  
Guojun Liu ◽  
Yuan Zhao ◽  
Yugang Cheng
Keyword(s):  
Acoustic Emission ◽  
Crack Initiation ◽  
Crack Propagation ◽  
Initial Stress ◽  
Stress Ratio ◽  
Ct Scanning ◽  
Stress Conditions ◽  
Liquid Volume ◽  
Fracturing Process ◽  
Initiation Pressure

This paper examines the fracture propagation problems of supercritical carbon fracturing in low permeability shale. Acoustic emission monitoring and computerized tomography (CT) scanning methods were used to study the influence of initial stress ratios on crack initiation and propagation crack in fracturing experiments. The results show that crack initiation pressure and crack morphology are very different under different stress conditions. Under the condition of constant confining pressure, when the initial stress ratio λ = 1, cracks are mainly in a horizontal direction; while for an initial stress ratio of λ < 1, cracks are mainly in a vertical direction. With the decrease of λ, crack initiation pressure, reopening pressure, and fracturing liquid volume also decrease, and crack propagation is not as obvious. According to CT scanning results, the crack propagation direction is the same as the maximum principal stress, and fewer cracks are initiated with a smaller initial stress ratio. Based on the acoustic emission characteristics, the fracturing process (including crack initiation, propagation, and closure), can be divided into three stages: 1) the pressure accumulation in the wellbore, 2) Pump Closure; and 3) crack reopening. This study provides the basis for a reasonable selection of shale gas fracturing formation and geo-sequestration of greenhouse gas CO2.

Dynamic Rupture Scenarios of Large Earthquakes on the Rodgers Creek-Hayward-Calaveras-Northern Calaveras Fault System, California

2021 ◽  
Author(s):  
Ruth Harris ◽  
Michael Barall ◽  
David Ponce ◽  
Diane Moore ◽  
Russell Graymer ◽  
...  
Keyword(s):  
Initial Stress ◽  
Active Faults ◽  
Large Earthquake ◽  
Stress Conditions ◽  
Rock Properties ◽  
Fault System ◽  
Fault Geometry ◽  
Dynamic Rupture ◽  
Field Samples ◽  
Large Earthquakes

<p>The Rodgers Creek-Hayward-Calaveras-Northern Calaveras fault system in California dominates the hazard posed by active faults in the San Francisco Bay Area. Given that this fault system runs through a densely populated area, a large earthquake in this region is likely to affect millions of people. This study produced scenarios of large earthquakes in this fault system, using spontaneous (dynamic) rupture simulations. These types of physics-based computational simulations require information about the 3D fault geometry, physical rock properties, fault friction, and initial stress conditions. In terms of fault geometry, the well-connected multi-fault system includes the Hayward fault, at its southern end the Central and Northern Calaveras faults, and at its northern end the Rodgers Creek fault. Geodetic investigations of the fault system’s slip-rate pattern provide images of where the fault surfaces at depth are creeping or locked interseismically, and this helped us choose appropriate initial stress conditions for our simulations. A 3D geologic model of the fault system provides the 3D rock units and fault structure at depth, while field samples from rocks collected at Earth’s surface provide frictional parameters. We used this suite of information to investigate the behavior of large earthquake ruptures nucleating at various positions along this partially creeping fault system. We found that large earthquakes starting on the Hayward fault or on the Rodgers Creek fault may be slowed, stopped, or unaffected in their progress, depending on how much energy is released by the creeping regions of the Hayward and Central Calaveras faults during the time between large earthquakes. Large earthquakes starting on either the Hayward fault or the Rodgers Creek faults will likely not rupture the Northern Calaveras fault, and large earthquakes starting on either the Northern Calaveras fault or the Central Calaveras fault will likely remain confined to those fault segments.</p>

Effect of Complex Initial Stress Conditions on Dynamic Deformation Behaviors of Compacted Loess

2011 ◽  
Vol 90-93 ◽  
pp. 67-73 ◽  
Author(s):  
Da Wei Cheng ◽  
Ya Sheng Luo ◽  
Li Guo Yang ◽  
Xi Chen
Keyword(s):  
Principal Stress ◽  
Initial Stress ◽  
Dynamic Deformation ◽  
Damping Ratio ◽  
Stress Conditions ◽  
Dynamic Shear Modulus ◽  
Initial Stress State ◽  
Triaxial Apparatus ◽  
Deformation Behaviors ◽  
Compacted Loess

In practical projects, foundations or roadbeds soil is usually in complex initial stress states, and deformation and settlement may happen caused by earthquakes or other dynamic loadings. Since conventional laboratory soil test cannot authentically reproduce dynamic behaviors of soils under complex initial consolidation stress conditions, dynamic deformation behaviors of compacted loess is conducted under complex initial stress conditions through remodeled DTC-199 torsional cyclic load triaxial apparatus. The paper systematically investigated the effects of different initial stress state, such as average principal stress p0, the angle of initial principal stress α0and the initial intermediate principal stress coefficient b0, etc. on dynamic shear modulus Gdand damping ratio λ. Results show that: (1) To the same γd, Gdincreases with the increase of p0but the α0and b0have no influence on Gd. (2) The α0has a little influence on λ and the p0and b0 have no influence on λ.

Self-Injurious Behavior vs. Nonsuicidal Self-Injury

Crisis ◽  
2012 ◽  
Vol 33 (2) ◽  
pp. 106-112 ◽  
Author(s):  
Christopher M. Bloom ◽  
Shareen Holly ◽  
Adam M. P. Miller
Keyword(s):  
Positive Reinforcement ◽  
Empirical Investigation ◽  
High Stress ◽  
Animal Research ◽  
Stress Conditions ◽  
Human Populations ◽  
Pharmacological Interventions ◽  
Self Injury ◽  
Cns Stimulant ◽  
Nonsuicidal Self Injury

Background: Historically, the field of self-injury has distinguished between the behaviors exhibited among individuals with a developmental disability (self-injurious behaviors; SIB) and those present within a normative population (nonsuicidal self-injury; NSSI),which typically result as a response to perceived stress. More recently, however, conclusions about NSSI have been drawn from lines of animal research aimed at examining the neurobiological mechanisms of SIB. Despite some functional similarity between SIB and NSSI, no empirical investigation has provided precedent for the application of SIB-targeted animal research as justification for pharmacological interventions in populations demonstrating NSSI. Aims: The present study examined this question directly, by simulating an animal model of SIB in rodents injected with pemoline and systematically manipulating stress conditions in order to monitor rates of self-injury. Methods: Sham controls and experimental animals injected with pemoline (200 mg/kg) were assigned to either a low stress (discriminated positive reinforcement) or high stress (discriminated avoidance) group and compared on the dependent measures of self-inflicted injury prevalence and severity. Results: The manipulation of stress conditions did not impact the rate of self-injury demonstrated by the rats. The results do not support a model of stress-induced SIB in rodents. Conclusions: Current findings provide evidence for caution in the development of pharmacotherapies of NSSI in human populations based on CNS stimulant models. Theoretical implications are discussed with respect to antecedent factors such as preinjury arousal level and environmental stress.

Flavonoid profiling by LC-MS IN 14 – 3-3ν knockout mutants of Arabidopsis thaliana during drought stress conditions

Planta Medica ◽  
2014 ◽  
Vol 80 (10) ◽  
Author(s):  
F Nabbie ◽  
O Shperdheja ◽  
J Millot ◽  
J Lindberg ◽  
B Peethambaran
Keyword(s):  
Arabidopsis Thaliana ◽  
Drought Stress ◽  
Stress Conditions ◽  
Knockout Mutants
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