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Fracture mechanics solution for control fissures in perilous rock under seepage stress

Chongqing Jianzhu Daxue Xuebao/Journal of Chongqing Jianzhu University 2008年第5期30卷 77-80页

作者： Chen, Hong-Kai Zhang, Yi Institute of Geotechnical Engineering Chongqing Jiaotong University Chongqing 400074 China Key Lab. for the Exploitation of Southwestern Resources and Envir. Disaster Control Eng. Min. of Ed Chongqing University Chongqing 400044 China

Crack propagation of control fissures in perilous rock under loads is a key process in the failure of perilous rock. Based on the loading mechanism, the control fissures are classified into compression-shear and tension-shear types. By introducing a model of seepage stress, the calculating principle of the stress intensity factor and the propagation orientation of control fissure under seepage stress are put forward using fracture mechanics methods. Using Shoulishan perilous rock in the Wanzhou district of Chongqing, P.R. China, as an example, the calculated results show that there is an obvious increase of the stress intensity factor. The influence of hydrostatic pressure and hydrodynamic pressure also are analyzed.

关键词： control fissure Fracture mechanics Perilous rock Rock mechanics Seepage stress Stress intensity factor

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Influence on strength characteristic of pile-soil composite with different moisture content

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Hunan Daxue Xuebao/Journal of Hunan University Natural Sciences 2008年第SUPPL.期35卷 49-53页

作者： Liao, Hong-Jian Zhang, Xin-Shan Li, Zhen-Dong Key Lab. for Exploitation of Southwestern Resources and Environ. Disaster Control Eng. Chongqing 400044 China Dept. of Civil Engineering Xi'an Jiaotong Univ. Xi'an 710049 China China Northwest Building Design Research Institute Xi'an 710003 China

Based on the fact that the physical and mechanical parameters of soil surrounding the foundation pile will change due to compacting effect of the pile, a series of direct shear tests on composite of concrete specimen and soil with different moisture content are performed with an improved direct shear apparatus. The relations between shear stress and strain of the composite as well as the effect of soil moisture content on the strength characteristic of the composite are studied. Based on the theory of cavity expansion, the elastic-plastic stress and strain formulas of the soil surrounding the pile are derived. According to the laws of variation of strength index with moisture content, the effect of moisture content on the radius of the plastic zone and the stress state of soil surrounding the pile are analyzed, which can be referenced in the engineering practice.

关键词： Piles

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Modeling experiment on developing processes for debris flow on slope

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Hunan Daxue Xuebao/Journal of Hunan University Natural Sciences 2008年第SUPPL.期35卷 130-134页

作者： Chen, Hong-Kai Xian, Xue-Fu Tang, Hong-Mei Wang, Quan-Cai Zhang, Yu-Ping Key Lab. For Exploitation of Southwestern Resources and Environ. Disaster Control Eng. Chongqing Univ. Chongqing 400044 China Department of Geotechnical and Geological Engineering Chongqing Jiaotong Univ. Chongqing 400074 China Chengdu Institute of Mountain Hazard and Environment Chinese Academy of Sciences Chengdu 610041 China

Based on dynamic geomorphology, general developing model for debris flow on slope was put forward. Further, in views of scale similarity, model soils and pricipitation devices, one semi-quantitative-qualitative experiment model was established, meanwhile, the experiment schedule was clarified. Precipitation durations vary 140-300 minutes, and it belongs to the previous precipitation stage from beginning to 70 minutes, rainfall velocity is below 1.5 mm/min, while the intense precipitation stage after 115 minutes, rainfall velocity is controlled in 2.5-5.0 mm/min. Experimental results identify five stages for developing processes of debris flow on slope, i.e., soil strength attenuation after sorping water, soil creep deformation, local sliding, flow and deposit. Physical behaviours every stages are discussed in detail, and some necessary mechanical principles are suggested in future mechanical analyses for every stages.

关键词： Geomorphology

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SLECTION OF WAVELET FUCTION ON DENOISE QULITIES OF ULTRASONIC INSPECTION SIGNAL

SLECTION OF WAVELET FUCTION ON DENOISE QULITIES OF ULTRASONI...

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3rd Symposium on Piezoelectricity, Acoustic Waves and Device Applications

作者： Zhang, Wei-wei Ma, Hong-wei Wang, Zhi-hua Jinan Univ Minist Educ China Dept Civil Engn & Mech West 601Huangpu Rd Guangzhou 510632 Guangdong Peoples R China Jinan Univ Minist Educ China Key Lab Disaster Forecast & Control Engn West 601Huangpu Rd Guangzhou 510632 Guangdong Peoples R China Taiyuan Univ Technol Inst Appl Mech Taiyuan 030024 Peoples R China

ISBN: (纸本)9781424428915

It is suggested in this paper to denoise the ultrasonic inspection signals using wavelet transform. The theoretic base is that wavelet transform is a band-pass filter. Firstly, the frequencies of the inspection signal are evaluated according to the excited signal. Secondly. an appropriate scale for wavelet transform is computed following the laws between the scale and the frequency. Thirdly, wavelet transform with the scale would be operated. As results, the echoes by the flaws could be discerned in the wavelet coefficients. Finally, the propagation of the guided wave in a damaged pipe is simulated by code ANSYS and the signal processing are operated by code MATlab. The different wavelet functions are also discussed aiming at the denoised qualities. The signal-to-noise ratio (SNR) is used to evaluate the quality for different wavelet. It Could be concluded that the Morlet wavelet is suitable to operate the ultrasonic inspection signal excited by a sinusoidal signal modulation by Harming windows.

关键词： Damage detection pipe wavelet crack

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Effect of Overlaid Material on Optical Transmission of Side-Polished Fiber Made by Wheel Side Polishing

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Journal of Electronic Science and Technology 2008年第4期000卷

作者： Z. Chen C.-H. Bai Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education of China Jinan University Guangzhou and Department of Optoelectronic Engineering.Jinan University Guangzhou 510632 China

The performance of optical power transmission through a side-polished fiber on which materials of different refractive indices were overlaid is investigated. The experiments show that the transmitted optical power through the side-polished fiber varies with the refractive index of the overlaid material. The result of our experiments fits well the theoretical calculation. Side-polished fiber manufactured by wheel polishing method can be used not only to control optical power transmission through the fiber core but also as a refractive index sensor.

关键词：光学纤维光学功率光学传输折射

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Study on damages constitutive model of rocks based on lognormal distribution

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Journal of Coal Science & engineering(China) 2007年第4期13卷 430-433页

作者：李树春许江陶云奇唐晓军 Key lab. for the Exploitation of Southwestern Resources ＆ the Environmental Disaster Control Engineering Ministry of Education Chongqing University Chongqing 400044 China

The damage constitutive relation of entire rock failure process was established using the theory of representative volume element obeying the Iognormal distribution law, and the integrated damages constitutive model of rock under triaxial compression was established. Comparing with triaxial compression test result, it shows that this model correctly reflects the relationship of stress-strain. At the same time, according to the principle of the rock fatigue failure that conforms to completely the static entire process curve, a new method of establishing cyclic fatigue damage evolution equation was discussed, this method form is simple and the physics significance is clear, it may join preferably the damage relations of the rock static entire process curve.

关键词： constitutive model rock damage fatigue

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Predict gas emission quantity of mining coal face with improved grey Markov model

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Meitan Xuebao/Journal of the China Coal Society 2007年第4期32卷 391-395页

作者： Tao, Yun-Qi Xu, Jiang Li, Shu-Chun Key Lab. for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering Chongqing University Chongqing 400044 China

In order to predict the absolute gas emission quantity of mining coal face, the improved grey model GM (1,1) was built based on dealing with the initial data of the gas emission quantity of mining coal face by natural logarithm. The improved grey Markov prediction mode was built through uniting the improved grey model (1,1) and the Markov model. Use this model to analyze and predict the the gas emission quantity of the first mining coal face in Zhongling Mine. It shows that the forecast result of grey Markov prediction model has better fitting precision and correct dependability. It has certain general employing.

关键词： Gas emission quantity Grey Markov Grey model (1,1)

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Effects of deformation field, coalification degree and the electronic field on the seepage law of methane gas in coal

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Xi'an Shiyou Daxue Xuebao (Ziran Kexue Ban)/Journal of Xi'an Shiyou University, Natural Sciences Edition 2007年第2期22卷 89-91页

作者： Xian, Xue-Fu Gu, Min Du, Yun-Gui Key Lab. of Exploitation of Southwestern Resources Environmental Disaster Control Engineering MOE Chongqing University Chongqing 400044 China

The effects of strain field, coalification degree and externally applied electronic field on the seepage performance of methane gas in coal are studied. It is shown that, the greater the stress (strain) in coal, the less the permeability coefficient of methane gas in the coal;when the stress (strain) is the same, the higher the coalificaton degree, the less the permeability coefficient;the stronger the externally applied electric field, the greater the permeability coefficient. The modified Darcy's law under the effects of stress field and electronic field are presented.

关键词： Coalification degree Electronic field Methane gas Seepage Strain field

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Method of in-situ stress measurement by boring core deformation

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Meitan Xuebao/Journal of the China Coal Society 2007年第3期32卷 248-252页

作者： Chen, Qu Xu, Jiang Zhou, De-Pei School of Civil Engineering Southwest Jiaotong University Chengdu 610031 China Key Lab. for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering Chongqing University Chongqing 400044 China Faculty of Engineering Sojo University Kumamoto 860-0082 Japan

Probed into a new method to measure in-situ stress - core deformation method, which depends on measuring the variation of core diameter. Assured its serviceability through the preparatory experiment and the actual measurement. The results show that the principal stress value and the principal stress direction in plane correspond with the loading. Moreover, investigated the relation among the P wave velocity, the micro-crack in rock with the variation of core diameter. The core deformation method supplies the in-situ stress measurement with a new method, Because it doesn't need to arrange the core and it can apply to a variety of stones under un-failure.

关键词： Core deformation method In-situ stress measurement Micro-crack

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Simulation and the model of activated sludge process reactor with secondary settling tank

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Zhongguo Huanjing Kexue/China Environmental Science 2007年第2期27卷 155-159页

作者： Zhang, Dai-Jun Li, Zhen-Liang Lu, Pei-Li Zhang, Tian Pang, Zi-Shan Key Lab. for the Southwest Resources' Exploitation and Environmental Disaster Control Engineering Department of Environmental Science Chongqing University Chongqing 400030 China Chongqing Education College Chongqing 400067 China Corporation Limited Chongqing 400020 China

An activated sludge process model was established using 1-D flux model of the secondary settling tank coupled with ASM2, and was applied to certain wastewater treatment plant (WWTP) in Chongqing. This model could simulate relatively well the COD, SS, TN and TP in the effluent. Based on the present operation conditions of the plant the factors influencing the activated sludge system were analyzed with suggesting the optimized operation parameters: the sludge recycle ratio of the secondary settling tank was decreased from original 0.75 to 0.20~0.25. The residual sludge discharge amount was decreased from original 591 m3/d to 204~249 m3/d, the reactor sludge concentration increased from original 1.2 g/L to 2.8 g/L. Therefore, the abilities of the system for resisting the loading impact and low temperature was enhanced and the effluent quality was improved.

关键词： Activated sludge process Mathematic model Reactor Secondary settling tank Simulation optimization

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