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Analysis of solid-fluid coupling for tunnel excavation in complicated fractured rock masses

Tumu Jianzhu yu Huanjing Gongcheng/Journal of Civil, Architectural and Environmental engineering 2010年第2期32卷 35-39+52页

作者： Zhao, Yu Lu, Yi-Yu Huang, Cheng Kang, Yong College of Civil Engineering Chongqing University Chongqing 400044 China Key Lab. for the Exploitation of Southwestern Resources and Environmental Disaster Control Eng. Chongqing University Chongqing 400044 China Key Laboratory of Rock and Soil Mechanics Institute of Rock and Soil Mechanics Chinese Acad. of Sci. Wuhan 430071 China

When tunnels are through water-bearing section of fractured rock mass, a complex interaction process between rock mass deformation and fluid transportation is one of the most important reasons for water gushing, water bursting and mud bursting. To study the rock mass deformation and fluid transportation in tunnel excavation under complex geological conditions, a hydraulic model of complex crack rock mass was established from the relationship between the crack growth degree of surrounding rock in deep buried tunnel and the engineering scale, with which fracture network of different levels in rock mass could be considered simultaneously. Furthermore, a computer Fortran program was put forward to simulate the solid-fluid coupling of excavation process of a deep buried tunnel. And it was found that the principal fractures had strong flowing action and network fractures had storage function and lag effect in seepage area. And the yield area of surrounding rock was increased under the coupling of seepage field and stress field.

关键词： Fracture

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THEORETICAL MODEL ON INTERFACE FAILURE MECHANISM OF REINFORCED CONCRETE CONTINUOUS BEAM STRENGTHENED BY FRP

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Acta Mechanica Solida Sinica 2009年第2期22卷 161-170页

作者： Hong Yuan Zifeng Lin MOE Key Lab of Disaster Forecast and Control in Engineering Institute of Applied Mechanics Jinan University Guangzhou 510632 China

Fiber reinforced polymer （FRP） composites are increasingly being used for the re-pair and strengthening of deteriorated concrete structural components through adhesive bonding of prefabricated strips/plates and the wet lay-up of fabric. Interfacial bond failure modes have attracted the attention of researchers because of the importance. The objective of the present study is to analyse the interface failure mechanism of reinforced concrete continuous beam strength-ened by FRP. An analytical solution has been firstly presented to predict the entire debonding process of the model. The realistic bi-linear bond-slip interfacial law was adopted to study this problem. The crack propagation process of the loaded model was divided into four stages （elastic,elastic-softening,elastic-softening-debonded and softening-debonded stage）. Among them,elastic-softening-debonded stage has four sub-stages. The equations are solved by adding suitable stress and displacement boundary conditions. Finally,critical value of bond length is determined to make the failure mechanism in the paper effective by solving the simultaneously linear algebraic equations. The interaction between the upper and lower FRP plates can be neglected if axial stiffness ratio of the concrete-to-plate prism is large enough.

关键词： FRP interface bond-slip law critical length continuous beam ultimate load

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Experimental analysis on the deformation of sandstone under pore pressure and constant time

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Tumu Jianzhu yu Huanjing Gongcheng/Journal of Civil, Architectural and Environmental engineering 2010年第2期32卷 19-25页

作者： Xu, Jiang Yang, Hong-Wei Peng, Shou-Jian Zhang, Yuan Li, Dao-Juan Jiang, Yong-Dong Key Lab. for Exploitation of Southwestern Resoureces and Environmental Disaster Control Engineering Chongqing University Chongqing 400044 China

In order to discuss the deformation characteristics of rock mass under different water levels changing between 145 and 175 meter in the Three Gorges reservoir area, an experiment was carried out for the studying sandstone deformation under the conditions of three different axial stresses (σ1=55.54, 34.18, 12.82 MPa), two cyclic pore pressures (Pmin=2 MPa, Pmax=6 MPa) and two kinds of constant time (the upper limit time and the lower limit time (ΔT=120, 240 s). With Ε1-T curves and p-T curves, as well as p-Ε1 hysteresis curves, it was found that the curves were continuous sine wave-shaped curves. At first, the strain decreased with loading pore pressure. And then, it decreased to valley value with pore pressure at stable upper limit. Next, it increased with unloading pore pressure and increased to peak value with pore pressure at stable lower limit. The p-Ε1 hysteresis curves of the sandstone had two typical stages. And one was caused by the closure of some primary pores and crack under increasing compaction, in which the strain did not form obviously hysteresis curves, and the other was pore pressure coupling stage which showed obvious hysteresis curve in form of the anti-clockwise from the dispersed to the dense. In addition, ΔΕ-n curves in four sections (loading, unloading, steady upper limit, steady lower limit) of p-Ε1 curves were compared and respectively ananlyzed in the condition of various axial stress and different constant time.

关键词： Unloading

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Study on the preparation of shaped active carbon by bituminous coal and its performance for concentrating methane from CH4/N2 by pressure swing adsorption

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Gongneng Cailiao/Journal of Functional Materials 2010年第2期41卷 204-207页

作者： Gu, Min Liu, Ke-Wan Xian, Xue-Fu Zeng, Lai Yao, Wei-Jing Key Lab. for the Exp. of Southwest Resources and the Environmental Disaster Control Engineering College of Resources and Environmental Science Chongqing University Chongqing 400044 China

Shaped active carbon adsorbents using bituminous coal from Chongqing mine as raw material for concentrating methane from CH4/N2 mixtures were prepared by taking carbonization-activation-deposition process and the effect of the preparation conditions on the pressure swing adsorption (PSA) concentrating performance was studied. The micro-structure characterization of active carbon was investigated by low temperature liquid nitrogen adsorption method. Experimental results showed that the methane concentration had increased 20.0vol% at the vacuum stage of PSA process with five steps using the shaped active carbon prepared as absorbent. As for one of the shaped active carbon adsorbents which concentrating effect was 20vol%, its BET specific surface area was 580m2/g, total micropore volume was 0.14cm3/g and its pore diameter size distribution was mostly between 2.0 and 4.0nm.

关键词： Methane

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Dynamic FE simulation of large-scale single-layer spherical shell with viscoelastic dampers

Dynamic FE simulation of large-scale single-layer spherical ...

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2009 Joint International Conference on Modelling and Simulation

作者： Yuan, Ping Li Wei, Zhang Key Lab. of Disaster Forecast and Control in Engineering Ministry of Education China Jinan University China Department of Mechanics and Civil Engineering Jinan University Guangzhou 510632 China

ISBN: (纸本)9781846260612

A vibration reduction system of viscoelastic dampers is introduced into Kewitte single-layer latticed spherical shell (D=60m). Through dynamic FE simulation, the stability of controlled shell and the correspondent uncontrolled one is compared. The different vibration schemes with initial geometric imperfection under different earthquake loadings are especially investigated. The results show that Liapunov stability of controlled shell with viscoelastic dampers can be evidently improved when compared with the uncontrolled shell;the vibration reduction is more obvious when considering the initial geometric imperfection of the shell. The damper's parameters have great influence on the vibration control effort.

关键词： Stability

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Studies on wavelet packet-based crack detection for a beam under the moving load

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key engineering Materials 2009年 413-414卷 285-290页

作者： Weiwei, Zhang Zhihua, Wang Hongwei, Ma College of Science and Engineering Jinan University Guangzhou 510632 China The Key Lab of Disaster Forecast and Control in Engineering Ministry of Edu. of China 510632 China Institute of Applied Mechanics Taiyuan University of Technology Taiyuan 030024 China

The objective of this study is to show the potential of the crack detection method based on Wavelet Packet Transform (WPT), which is depending on the response at a single point on a beam subject to moving load. In this paper, an A-SYS model of a cracked beam is established. The moving load is transient analyzed by shifting the point of the concentrated force. The response at mid-span of the beam is calculated and wavelet packet transformed. The crack on the beam can be found by the abnormal signal in WPT branches. The size is also estimated by a defined damage index (Dindex) which relates to the energy of the abnormal signal. Finally, the effects of both crack location and wavelet selection on Dindex are discussed in detail.

关键词： Damage detection

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Notice of Retraction: The Numerical Simulation of Crack Propagation without Re-Meshing

Notice of Retraction: The Numerical Simulation of Crack Prop...

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2009 International Conference on Information engineering and Computer Science, ICIECS 2009

作者： Yang, Shuai Wang, Hong Xia, Xiao-Zhou Yuan, Hong College of Civil and Transportation Engineering GDUT Guangzhou China Moe Key Lab of Disaster Forecast and Control in Engineering Institute of Applied Mechanics JNU Guangzhou China College of Civil Engineering HHU Nanjing China

ISBN: (纸本)9781424449941

After careful and considered review of the content of this paper by a duly constituted expert committee, this paper has been found to be in violation of IEEE's Publication *** hereby retract the content of this paper. Reasonable effort should be made to remove all past references to this *** presenting author of this paper has the option to appeal this decision by contacting TPII@***.

关键词： Cracks

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Scattering of SH-wave by a shallow U-shaped tunnel

Scattering of SH-wave by a shallow U-shaped tunnel

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Joint Conference of the 2009 Symposium on Piezoelectricity, Acoustic Waves, and Device Applications, SPAWDA 2009 and 2009 China Symposium on Frequency control Technology

作者： Chen, Zhi-Gang Key Lab. of Disaster Forecast and Control in Engineering Department of Mechanics and Civil Engineering Jinan University Guangzhou 510632 China

ISBN: (纸本)9781424449507

In general, analytical solution for the scattering problem of SH plane wave by a cavity in half-space primarily focused on the circular structure case. However, the case for U-shaped cavities, which are similar to the cross-section of the tunnels, was seldom mentioned in former references. The analytical solution for U-shaped cavity in elastic half space is gained by the multi-polar coordinate system and conformal mapping method. A scattering wave function satisfying zero-stress condition on horizontal surface is constructed in the complex plane, the problem can be inverted into a set of algebraic equations to solve coefficients of the scattering wave by least square method. The numerical examples of the dynamic stress concentration around U-shaped cavities and ground motion on subsurface U-shaped cavity impacted by SH-wave are given. The influences of the incident wave number, angle and depth are discussed. The research indicates that the shallow U-shaped tunnel has significant impact on wave propagation, and interaction between the U-shaped tunnel and the horizontal surface will complicate characteristics of ground motion, and will bring about great increase on dynamic stress around cavity. In this situation, enough attention should be paid on the interaction between the subsurface cavity and the horizontal surface in the seismic design of ground and underground structures. © 2009 IEEE.

关键词： Wave propagation

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Analysis of optical transmission characteristics in the waveguide of side polished fiber

Analysis of optical transmission characteristics in the wave...

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2009 International Conference on Optical Instruments and Technology, OIT'09

作者： Zhe, Chen Zuping, He Fei, Cui Yating, Xiao Jun, Zhang Key Laboratory of Disaster Forecast and Control in Engineering Ministry of Education Jinan University 510632 China Key Lab. of Optoelectron. Info. and Sensing Technologies of Guangdong Higher Educational Institutes Jinan University Guangzhou 510632 China Department of Optoelectronic Engineering Jinan University Guangzhou510632 China

ISBN: (纸本)9780819478948

According to the experimental results of side polished fiber (SPF), a three dimensional optical waveguide model with longitudinal side polished transition zones is built. Based on the model, characteristics of optical transmission are calculated and analyzed by three dimensional finite differential beam propagation method. The model describes the optical transmission characteristics because the calculation based on the model is fitted well with the experiments. The calculation shows that the length of side polished area affects the optical attenuation of optical fiber, but the attenuation does not increased monotonically with the length when the length is less than certain value. The relationship between optical attenuation of SPF and the thickness of residual side polished cladding is not a monotonie one as well. The refractive index of overly on the side polished area has much more effect on the optical attenuation. Both width and thickness of overlay on the side polished area cause the oscillated change of optical power attenuation in the fiber core. © 2009 SPIE.

关键词： Light transmission

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Outburst orientation of sandstone under gravitational field

Beijing Keji Daxue Xuebao/Journal of University of Science a...

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Beijing Keji Daxue Xuebao/Journal of University of Science and Technology Beijing 2009年第12期31卷 1487-1491+1502页

作者： Guo, Chen-Ye Xian, Xue-Fu Li, Xiao-Hong Yao, Wei-Jing Jiang, Yong-Dong Key Lab. for Exploitation of Southwestern Resources and Environmental Disaster Control Engineering Chongqing University Chongqing 400030 China

The characters of outburst sandstone in rocks from Yongchuan Coal Mine were studied on the base of experimental investigation on its physical and mechanical properties. The outburst orientation of sandstone at the -350 m horizontal in this coal was analyzed and the criterion of outburst orientation was proposed. The results show that outburst sandstone has the physical characteristics of big porosity and big blowhole volume, and the mechanical characteristics of low Young's modulus, low strength, and not easy to produce plastic deformation. The launch process of rocks and gas outburst has uniformity with the rockburst characteristic, and the rockburst theory can be used to study the outburst orientation of sandstone, which depends on many kinds of factors. In these factors the mechanical factor is primary. The assessment method of outburst orientation of sandstone was established based on the energy criterion, strength criterion, and impact orientation criterion.

关键词： Sandstone

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