PRESS-NEWS.org - Press Release Distribution
PRESS RELEASES DISTRIBUTION

Extended Coulomb failure criteria for the Zipingpu reservoir and Longmenshan slip

Extended Coulomb failure criteria for the Zipingpu reservoir and Longmenshan slip
2011-07-14
(Press-News.org) Describing the correlation of a reservoir and earthquake slip remains a great challenge. Professor SHI Yaolin and his group at the Key Laboratory of Computational Geodynamics of the Chinese Academy of Sciences and the College of Science of the Graduate University of the Chinese Academy of Sciences are attempting to solve this problem. On the basis of the laboratory's parallel central processing unit (CPU) and graphics processing unit (GPU) hardware platform, the micro FDPNC model for UTP conditions was established and the ECFS criteria and anisotropic porosity and permeability tensor, which includes pore pressure, pressure gradient, viscous stress and Reynolds stress, have been given. In the case of the Zipingpu reservoir and Longmenshan fault, the simulation results show that the extended viscous stress and Reynolds stress cannot be neglected. Their work, entitled "Application of flow driven pore-network crack model to Zipingpu reservoir and Longmenshan slip", was published in SCIENCE CHINA Physics, Mechanics & Astronomy, 2011, Vol. 54(8).

The interaction mechanism of a reservoir and fault slip has importance in terms of the economy, social security and other national issues as it relates to the effects of hydro-projects, landslides and reservoir earthquakes. Several approaches have been taken to study the mechanism owing to its complexity and social importance. The use of Coulomb failure theory is a classical method for addressing this problem and has provided many landmark achievements. However, it is not clear yet how water affects a fault slip, especially at a depth of about 10 km or more, which is an important consideration. It is suggested that Coulomb failure criteria should be improved by consideration of the viscous stress and Reynolds stress in addition to pore pressure and its gradient.

At this time, ultra-large high-performance computing hardware, parallel CPU & GPU simulation technology, fluid–solid coupled crack initiation and propagation theory and the multi-spatial-scale fluid FDPNC method provide research opportunities.

First, using micro-tomography data, the multi-spatial-scale flow-driven pore-network crack model was established, and the effects of viscous stress and Reynolds stress under UTP were determined for the first time (Figure 1).

Second, the hybrid hypersingular integral equation (HHIE) method and lattice Boltzmann (LBM) were combined to establish a link between the flow pore pressure and solid skeleton structure deformation/strength. The HHIE method deals with the crack initiation, propagation and transmission problem for the solid skeleton on multiple temporal–spatial scales (yellow in Figure 2 indicates the solid skeleton core), and the LBM deals with the flow-driven fluid pore problem on multiple temporal–spatial scales (black in Figure 2 indicates flow in pores). Combining the two methods, it is possible to study the coupled extended stress of the micro/meso/macro-scale structure at the interface of the pore and core by establishing the relationship between the extended pore fluid pressure and extended core stress, and analyze porosity and permeability under different initial and boundary conditions.

Finally, the relationship among the water-drainage sluice processes of a reservoir, stress triggers, earthquake shadows and porosity variability in a fault slip zone has been analyzed. The vadose energy (which results from pore pressure and can flow to the fault slip tip) differs for undrained and drained zones, with more energy being released in a drained zone than in an undrained zone. If the fault slip is a stable creep rupture process, the energy criteria (strain energy function factors) must increase with the rate at which the fault spreads. When penetration reaches a stable stage, the role of the initiation and propagation of the fluid FDPNC becomes dominant. As the time scale increases, the solid–fluid interface weakens and blurs microscopically, while macroscopically, the porosity increases. Strain energy is released during the slip process, and decreases as spreading increases in the drained zone.

The reservoir loading and earthquake trigger relationship depends on the fault-slip geometry and character, the porosity variability of the surrounding geological structure and the temporal and spatial scales. In the case of the Zipingpu reservoir and 2008 Wenchuan earthquake, the porosity and temporal scale are important factors, and they need to be investigated in further field and laboratory experiments.



INFORMATION:

Article: Zhu B J, Liu C, Shi Y L* et al. Application of flow driven pore-network crack model to Zipingpu reservoir and Longmenshan slip. SCI CHINA Physics, Mechanics & Astronomy, 2011, 54(8): 1-9


[Attachments] See images for this press release:
Extended Coulomb failure criteria for the Zipingpu reservoir and Longmenshan slip

ELSE PRESS RELEASES FROM THIS DATE:

Keeping up your overall health may keep dementia away

2011-07-14
ST. PAUL, Minn. – Improving and maintaining health factors not traditionally associated with dementia, such as denture fit, vision and hearing, may lower a person's risk for developing dementia, according to a new study published in the July 13, 2011, online issue of Neurology®, the medical journal of the American Academy of Neurology. "Our study suggests that rather than just paying attention to already known risk factors for dementia, such as diabetes or heart disease, keeping up with your general health may help reduce the risk for dementia," said study author Kenneth ...

Free Delivery Offer from Isme.com

2011-07-14
The limited time offer runs until 14th July and is available to new and existing customers who purchase standard, one man delivery items, and includes a wide range of branded ladies' fashion, homewares and electricals. Home shopping brand, isme.com is flying the flag for mature style-savvy shoppers. Aiming to redefine the shopping experience for Britain's mature female customer, isme.com is dedicated to delivering fashion that empowers, gives confidence and captures the key trends of the season with a style and fit created for today's mature woman. Isme.com carries ...

Stem cell treatment may restore cognitive function in patients with brain cancer

2011-07-14
PHILADELPHIA — Stem cell therapy may restore cognition in patients with brain cancer who experience functional learning and memory loss often associated with radiation treatment, according to a laboratory study published in Cancer Research, a journal of the American Association for Cancer Research. Charles Limoli, Ph.D., a professor in the department of radiation oncology at the University of California, Irvine, said radiation therapy is the standard of care for most brain cancers, but the side effects can be devastating. "In almost every instance, people experience ...

Short-term hormone therapy plus radiation therapy increases survival for men with early-stage prostate cancer

2011-07-14
Philadelphia — Short-term hormone therapy (androgen deprivation therapy: ADT) given in combination with radiation therapy for men with early-stage prostate cancer increases their chance of living longer and not dying from the disease, compared with that of those who receive the same radiation therapy alone, according to a Radiation Therapy Oncology Group (RTOG) study published in the July 14 issue of the New England Journal of Medicine. This largest randomized trial of its kind enrolled nearly 2,000 men at low and intermediate risk of prostate cancer progression and followed ...

A closer look at the placebo effect

2011-07-14
BOSTON – Placebos are "dummy pills" often used in research trials to test new drug therapies and the "placebo effect" is the benefit patients receive from a treatment that has no active ingredients. Many claim that the placebo effect is a critical component of clinical practice. But whether or not placebos can actually influence objective measures of disease has been unclear. Now a study of asthma patients examining the impact of two different placebo treatments versus standard medical treatment with an albuterol bronchodilator has reached two important conclusions: while ...

Neural mechanisms of object recognition

2011-07-14
A study examining the brain of a person with object agnosia, a defect in the inability to recognize objects, is providing a unique window into the sophisticated brain mechanisms critical for object recognition. The research, published by Cell Press in the July 14 issue of the journal Neuron, describes the functional neuroanatomy of object agnosia and suggests that damage to the part of the brain critical for object recognition can have a widespread impact on remote parts of the cortex. Object agnosia is caused by an injury to the brain that does not include damage to ...

Modulation of inhibitory output is key function of antiobesity hormone

2011-07-14
Scientists have known for some time that the hormone leptin acts in the brain to prevent obesity, but the specific underlying neurocircuitry has remained a mystery. Now, new research published by Cell Press in the July 14 issue of the journal Neuron reveals neurobiological mechanisms that may underlie the antiobesity effects of leptin. "Leptin is a hormone that is secreted by fat cells and acts at its receptor in the brain to decrease food intake and promote energy expenditure," explains senior study author Dr. Bradford B. Lowell from Beth Israel Deaconess Medical Center ...

Researchers demystify a fountain of youth in the adult brain

2011-07-14
DURHAM, NC -- Duke University Medical Center researchers have found that a "fountain of youth" that sustains the production of new neurons in the brains of rodents is also believed to be present in the human brain. The existence of a vital support system of cells around stem cells in the brain explains why stem cells by themselves can't generate neurons in a lab dish, a major roadblock in using these stem cells for injury repair. "We believe these findings will have important implications for human therapy," said Chay Kuo, M.D., Ph.D., George Brumley Jr. assistant professor ...

Gene migration helps predict movement of disease

2011-07-14
Until recently, migration patterns, such as those adopted by birds all across the Amazonian rainforest, have not been thought to play an important role in the spreading of beneficial genes through a population. Researchers have now, for the first time, been able to predict the chance of a gene spreading when given any migration pattern, potentially providing an insight into the migration patterns of animals throughout history. Even more impressively, the concepts from these predictions can be applied to tracking the route of cancer through the body, and viruses or ...

What activates a supermassive black hole?

What activates a supermassive black hole?
2011-07-14
At the heart of most, if not all, large galaxies lurks a supermassive black hole with a mass millions, or sometimes billions, times greater than that of the Sun. In many galaxies, including our own Milky Way, the central black hole is quiet. But in some galaxies, particularly early on in the history of the Universe [1], the central monster feasts on material that gives off intense radiation as it falls into the black hole. One unsolved mystery is where the material comes from to activate a sleeping black hole and trigger violent outbursts at a galaxy's centre, so that ...

LAST 30 PRESS RELEASES:

Study identifies candidates for therapeutic targets in pediatric germ cell tumors

Media alert: The global burden of CVD

Study illuminates contributing factors to blood vessel leakage

What nations around the world can learn from Ukraine

Mixing tree species does not always make forests more drought-resilient

Public confidence in U.S. health agencies slides, fueled by declines among Democrats

“Quantum squeezing” a nanoscale particle for the first time

El Niño spurs extreme daily rain events despite drier monsoons in India

Two studies explore the genomic diversity of deadly mosquito vectors

Zebra finches categorize their vocal calls by meaning

Analysis challenges conventional wisdom about partisan support for US science funding

New model can accurately predict a forest’s future

‘Like talking on the telephone’: Quantum computing engineers get atoms chatting long distance

Genomic evolution of major malaria-transmitting mosquito species uncovered

Overcoming the barriers of hydrogen storage with a low-temperature hydrogen battery

Tuberculosis vulnerability of people with HIV: a viral protein implicated

Partnership with Kenya's Turkana community helps scientists discover genes involved in adaptation to desert living

Decoding the selfish gene, from evolutionary cheaters to disease control

Major review highlights latest evidence on real-time test for blood – clotting in childbirth emergencies

Inspired by bacteria’s defense strategies

Research spotlight: Combination therapy shows promise for overcoming treatment resistance in glioblastoma

University of Houston co-leads $25 million NIH-funded grant to study the delay of nearsightedness in children

NRG Oncology PREDICT-RT study completes patient accrual, tests individualized concurrent therapy and radiation for high-risk prostate cancer

Taking aim at nearsightedness in kids before it’s diagnosed

With no prior training, dogs can infer how similar types of toys work, even when they don’t look alike

Three deadliest risk factors of a common liver disease identified in new study

Dogs can extend word meanings to new objects based on function, not appearance

Palaeontology: South American amber deposit ‘abuzz’ with ancient insects

Oral microbes linked to increased risk of pancreatic cancer

Soccer heading does most damage to brain area critical for cognition

[Press-News.org] Extended Coulomb failure criteria for the Zipingpu reservoir and Longmenshan slip