In this paper, we have investigated the quantitative relationship between the axial strain threshold at the volumetric strain reversal point (e 1cd) and the strain threshold at the peak stress (e 1ucs) during the uniaxial compression tests. We found that normalized values of e 1ucs/e 1cd for different rock types are typically ~1.34(±0.24). This is especially true for igneous and metamorphic rocks, or low-porosity sedimentary rocks. To verify this finding, we investigated seven granitic gneiss samples using the uniaxial compression test. Our results were consistent with the above statistics. We inferred that e 1ucs/e 1cd may be an intrinsic property of low-porosity rocks, and may be a potential indicator for predicting failure strains in laboratory-scale rock samples.
#1Lei Xue(CAS: Chinese Academy of Sciences)H-Index: 9
Based on the two-dimensional renormalization group model, which can consider the stress transfer mechanism, in the present paper, the theoretical quantitative correlation between the threshold of the crack damage stress (σ cd ) and the uniaxial compressive strength (σ ucs ) was constructed. The results indicate that the normalized quantity σ cd /σ ucs decreases as the shape parameter m increases, and that it gradually tends towards a constant horizontal asymptote that is ~0.82. In addition, the ...
Landslide displacement is widely obtained to discover landslide behaviors for purpose of event forecasting. This article aims to present a comparative study on landslide nonlinear displacement analysis and prediction using computational intelligence techniques. Three state-of-art techniques, the support vector machine (SVM), the relevance vector machine (RVM), and the Gaussian process (GP), are comparatively presented briefly for modeling landslide displacement series. The three techniques are d...
#1Lei Xue(CAS: Chinese Academy of Sciences)H-Index: 9
#2Siqing Qin(CAS: Chinese Academy of Sciences)H-Index: 13
Last. Haitao Qian(CEA: China Earthquake Administration)H-Index: 1
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Abstract It was found that the crack damage stress threshold, σ cd , is a phase transition point during the deformation process of rock and is equivalent to the unstable fixed point of renormalization group theory. Thus, a relationship exists between the renormalization group theory and the rock deformation process, through which we can investigate the critical behavior of rock deformation. Therefore, an improved renormalization group model, which takes into account the different stress transfer...
When rock samples are loaded until macroscopic fractures develop, the failure process can be divided into several stages based on axial and lateral strain responses or the acoustic emission sequence during uniaxial compression tests. Several stress thresholds may be identified: the crack closure stress σ cc, crack initiation stress σ ci, crack damage stress σ cd, and uniaxial compressive strength σ ucs; these may be used as a warning indicator for rock rupture. We investigated the crack damage s...
Abstract An Innovative Mathematical Model analysis was carried out based on twenty years of earthquake data from California, Central USA, Northeast USA, Hawaii, Turkey, and Japan fault zones using Latitude, Longitude and Magnitude as variables. Using Poisson’s distribution and spatial connection model, an identifiable pattern was found within the random occurrences of the earthquakes around each fault zone. This research provides an effective contribution to seismology by improving probability o...
#1Qin Siqing(CAS: Chinese Academy of Sciences)H-Index: 4
#2Xue Lei(CAS: Chinese Academy of Sciences)H-Index: 1
Last. LI Guo-Liang(CAS: Chinese Academy of Sciences)H-Index: 1
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Based on the brittle failure theory of multiple locked patches in a seismogenic fault system and the associated prediction method developed by us, we have released a medium- and long-term prediction of future strong earthquakes in the Yutian seismic zone of Xinjiang, including the magnitude, location, critical Benioff strain, and focal depth. Comparison shows that these parameters are almost identical with the Yutian Ms7.3 event in Xinjiang on 12 February 2014, which indicates that our previous ...
#1A. Farahmand(UCI: University of California, Irvine)H-Index: 9
#2Amir AghaKouchak(UCI: University of California, Irvine)H-Index: 63
Abstract. Landslides are devastating phenomena that cause huge damage around the world. This paper presents a quasi-global landslide model derived using satellite precipitation data, land-use land cover maps, and 250 m topography information. This suggested landslide model is based on the Support Vector Machines (SVM), a machine learning algorithm. The National Aeronautics and Space Administration (NASA) Goddard Space Flight Center (GSFC) landslide inventory data is used as observations and refe...
Rock mass usually is composed of joints and rock bridges,many failure cases of rock mass engineering were induced by the sudden brittle failure of rock bridges.In this paper,the percolation model of brittle failure was established firstly and supposing the strength distribution of rock obeyed weibull function,then the percolation thresholds of one-dimension and two-dimension models were computed by the renormalization group methods.Furthermore,the critical state features of the three-dimension p...
#2Erling Nordlund(Luleå University of Technology)H-Index: 16
The aim of this paper was to compare the stress and strain quantities that are related to the failure–deformation process of hard rock. The data used here was obtained from laboratory uniaxial compression tests performed on different types of Fennoscandian hard rocks. The failure–deformation process quantities were compared at each deformation stage and for each single specimen. Moreover, geological information such as the rock origin process and the rock characteristics of the specimens were st...
The study of the force chains and acoustic emission response laws of rock masses are of major significance for the prediction and prevention of stope dynamic disasters. In the present study, the response law of the force chains and acoustic emissions of rock specimens were examined using numerical simulation and laboratory testing based on the theory of moment tensor, along with the macro–mesoscopic damage characteristics and the evolution laws of force chains and acoustic emissions. The researc...
Last. Yan Zhang(NU: Northeastern University)H-Index: 5
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The rock failure process can be characterized by several distinct stress thresholds: the crack closure stress σcc, crack initiation stress σci, crack damage stress σcd and peak stress σp. Seventy-one true triaxial compression tests were conducted to investigate the crack damage stress σcd, which is the stress at the onset of unstable crack development and dilation. Two empirical models are developed to predict the crack damage stress σcd using the intermediate principal stress σ2 and the minimum...
Despite the enormous efforts towards searching for precursors, no precursors have exhibited real predictive power with respect to an earthquake thus far. Seismogenic locked segments in a well-defined seismic zone that can accumulate adequate strain energy to cause major earthquakes are very heterogeneous and less brittle. Progressive failures of the locked segments with these properties can produce an interesting seismic phenomenon: a characteristic earthquake and a sequence of smaller subsequen...
Abstract Cracking processes have been extensively studied in brittle rock and rock-like materials. For a better understanding of failure processes, moment tensor is used to distinguish the nature of primary cracks and secondary cracks in a single-flaw-contained specimen based on the bonded-particle model, which can indicate the force applying on the failure source. The results reveal that the primary cracks solely consist of micro-tensile cracks and the failure nature is tensile, while the secon...
#1Yuan Li(CAS: Chinese Academy of Sciences)H-Index: 2
#2Ke Zhang(CAS: Chinese Academy of Sciences)H-Index: 1
Last. Xiaowa Wu(Beijing University of Technology)H-Index: 1
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Changes in the velocity, amplitude and attenuation of ultrasonic waves are accompanied by physical changes during rock failure. A large number of triaxial compression tests were performed to study the progressive failure of shale rock according to these physical properties. The tested shale samples had different bedding planes and were subjected to different confining pressures. During the experiments, ultrasonic wave testing was used to monitor the progressive failure process and to evaluate di...
#1Xiaohan Yang(UOW: University of Wollongong)H-Index: 4
#2Ting Ren(UOW: University of Wollongong)H-Index: 25
Last. Xueqiu He(USTB: University of Science and Technology Beijing)H-Index: 5
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Abstract Coal burst is the violent failure of overstressed coal, and it is often accompanied by sound, coal ejection and seismic events. It is subsequently recognized as a serious safety risk of Australia after double fatalities coal burst happened at Austar Coal Mine. Considering the increasing trend of coal burst severity and frequency with mining depth, it is an urgent task to develop the coal burst risk assessment methods for Australia underground coal mines. Coal burst propensity index meth...
#1Hong-Ran Chen(CAS: Chinese Academy of Sciences)H-Index: 2
#2Siqing Qin(CAS: Chinese Academy of Sciences)H-Index: 13
Last. Ke Zhang(CAS: Chinese Academy of Sciences)H-Index: 2
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Abstract Better understanding the evolutionary mechanism of landslides is very important to predict their occurrence based on firm scientific grounds. The stability of a rock slope is often dominated by one or more locked segments along a potential slip surface with a large bearing capacity to resist instability. We propose three preliminary categories for locked segments and develop a physical model for predicting the instability of rock slopes with locked segments, by coupling a one-dimensiona...
Strain energy is one of the key factors that control the brittle failure process of rock mass, such as the onset of accelerating displacement. The phenomenon of accelerating displacement is a necessary and important precursor to predict the brittle failure of rock, and it is attributed to the unstable propagation of micro-cracks when the load reaches or exceeds the crack damage stress threshold. Thus, for the design of underground rock engineering and to ensure proper safety practices, it is imp...
The Rock Engineering Laboratories of Rock Engineering Department of Aalto University Helsinki Finland and School of Mining Engineering Wits University South Africa are appreciated for allowing part of this work to be done there.
