检索结果-南通市图书馆

An experimental study on seepage behavior of sandstone material with different gas pressures

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第6期31卷 837-844页

作者： Sheng-Qi Yang Yan-Hua Huang Yu-Yong Jiao Wei Zeng Qing-Lei Yu State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil Engineering China University of Mining and Technology institute of rock and Soil mechanics Chinese Academy of Sciences School of Resource and Civil Engineering Northeastern University

The seepage evolution characteristic of brittle rock materials is very significant for the stability and safety of rock engineering. In this research, a series of conventional triaxial compression and gas seepage tests were carded out on sandstone specimens with a rock mechanics servo-controlled testing system. Based on the experimental results, the relationship between permeability and deformation is firstly analyzed in detail. The results show that the permeabilityaxial strain curve can be divided into the following five phases： the phase of micro-defects closure, the phase of linear elastic deformation, the phase of nonlinear deformation, the phase of post-peak stress softening and the phase of residual strength. The seepage evolution characteristic is also closely correlated with the volumetric deformation according to the relationship between permeability and volumetric strain. It is found that the gas seepage pressure has a great effect on the permeability evolution, i.e. permeability coefficients increase with increasing gas seepage pressures. Finally, the influence of gas seepage pressures on the failure behavior of brittle sandstone specimens is discussed.

关键词： rock mechanics · Sandstone · Gas seepage ·Volumetric deformation · Permeability

An improved three-dimensional spherical DDA model for simulating rock failure

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2015年第9期58卷 1533-1541页

作者： JIAO YuYong HUANG GangHai ZHAO ZhiYe ZHENG Fei WANG Long State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences School of Civil and Environmental Engineering Nanyang Technological University

In this paper, a discontinuous numerical model, namely SDDARF3D(three-dimensional spherical discontinuous deformation analysis for rock failure), is proposed for simulating the whole process of rock failure. Firstly, within the framework of the classical discontinuous deformation analysis(DDA) method, the formulation of three-dimensional spherical DDA(3D SDDA) is deduced; secondly, a bonding and cracking algorithm is constructed and the SDDARF3 D model is proposed; thirdly, corresponding VC++ calculation code is developed and some verification examples are calculated. The simulated results can intuitively reproduce the failure phenomena of rock mass, indicating that the proposed SDDARF3 D numerical model is correct and effective.

关键词： rock failure three-dimensional spherical discontinuous deformation analysis crack propagation bonding and cracking algorithm

Deformations of surface and rock mass in salt mines of Southern Poland

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 2005年第S1期15卷 310-314页

作者： J .Szewczyk G. Kortas StanisΙaw Staszic AGH-University of Science and Technology CracowPolandInstitute of Rock Mass Mechanics PAN-Polish Academy of Science CracowPoland

The existing salt mines "Wieliczka" and "Bochnia", where the exploitation of rock salt was going on since 14th century, have recently finished their mining activities. In the rock mass, however, old workings remained. They are often inaccessible and not inventoried properly. Clamping of such workings causes deformations in the rock mass itself and on the surface of the area. The specifics of physical properties of salt rock mass and also the applied exploitation systems influence the course of the deformation process. The complete image of this process also includes the changes of water balance in the rock mass and consequently water suffosion, landslide processes and the movements of the Carpathian Mountains that have not been examined satisfactorily so far. Many years lasting observations of the deformations of the area surface and mine workings allow defining their course and interpreting the obtained results. For the last ten years in order to study deformations the author has applied modern observation techniques: satellite methods (GPS), total stations of high measurement precision, precise leveling, the measurements of the convergence of mine workings and laser scanning. The results have been statistically and geostatistically analyzed. This results in interesting data referring to the course of deformation processes and enables to deal with the problem of securing old workings to minimize the damage.

关键词： rock Deformations of surface and rock mass in salt mines of Southern Poland

Sediment rarefaction resuspension and contaminant release under tidal currents

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2014年第5期26卷 827-834页

作者：程鹏达朱红伟钟宝昌王道增 Shanghai institute of Applied Mathematics and mechanics Shanghai University institute of mechanics Chinese Academy of Sciences

Based on experiment in tidal flume, this paper analyzes the sediment rarefactive phenomenon and hydraulic characteristics of sediment resuspension with different physical properties under the effect of tidal current. According to this experiment, sediment resuspension is related to the hydraulic characteristics of overlying water and its own dry density, namely the moisture content of sediment and deposition time. Generally, river sediment can be classified into the upper layer of floating sludge and lower layer of deposit sediment. Incipient velocity goes higher as the sediment layer goes thicker. Based on the experiment, incipient velocity formula of sediment can be obtained. There is a cohesive force among natural fine sediment whose resuspension is almost irrelevant to their diameters. Therefore, the critical incipient velocity is determined by the cohesive force instead of particle diameter. The lower layer of deposit sediment is generally not so easy to start up. And it will be rarified and release into the overlying water when contacting with overlying water. However, this rarefaction release velocity is gentle and slow. Under the same flow condition, annual loss amount of lower layer deposited sediment is about one fifth of upper layer of floating sediment. Flow velocity of tidal river and variation of the water level are asymmetrical, both of which vary under different tidal cycles. During long tidal cycle, flow velocity and water level change in the same phase and amplitude with tide. During the whole ebb and flow, flow direction does not change as the water level goes under the influence of acceleration and deceleration. As the tide cycle increases, the incipient velocity of sediment goes higher. This means that the long period tide cycle plays buffer effect on the resuspension of sediment, which makes the sediment not so easy both to start up and to suspend.

关键词： tidal current tidal cycle incipient velocity dry density resuspension hydraulic characteristics

Transport mechanisms of contaminants released from fine sediment in rivers

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Sinica 2015年第6期31卷 791-798页

作者： Pengda Cheng Hongwei Zhu Baochang Zhong Daozeng Wang institute of mechanics Chinese Academy of Sciences Shanghai institute of Applied Mathematics and mechanics Shanghai University

Contaminants released from sediment into rivers are one of the main problems to study in environmental hydrodynamics. For contaminants released into the overlying water under different hydrodynamic conditions, the mechanical mechanisms involved can be roughly divided into convective diffusion, molecular diffusion, and adsorption/desorption. Because of the obvious environmental influence of fine sediment （D90 = 0.06 mm）, non-cohesive fine sediment, and cohesive fine sediment are researched in this paper, and phosphorus is chosen for a typical adsorption of a contaminant. Through theoretical analysis of the contaminant release process, according to different hydraulic conditions, the contaminant release coupling mathematical model can be established by the N-S equation, the Darcy equation, the solute transport equation, and the adsorption/desorption equation. Then, the experiments are completed in an open water flume. The simulation results and experimental results show that convective diffusion dominates the contaminant release both in non-cohesive and cohesive fine sediment after their suspension, and that they contribute more than 90 % of the total release. Molecular diffusion and desorption have more of a contribution for contaminant release from unsuspended sediment. In unsuspension sediment, convective diffusion is about 10-50 times larger than molecular diffusion during the initial stages under high velocity; it is close to molecular diffusion in the later stages. Convective diffusion is about 6 times larger than molecular diffusion during the initial stages under low velocity, it is about a quarter of mole- cular diffusion in later stages, and has a similar level with desorption/adsorption. In unsuspended sediment, a seepage boundary layer exists below the water-sediment interface, and various release mechanisms in that layer mostly dominate the contaminant release process. In non-cohesive fine sediment, the depth of that layer increases linearly with shear st

关键词： Cohesive Diffusion Seepage boundarylayer. Adsorption/desorption Coupling

Study on the Constitutive Model of Marble Based on the Conventional Triaxial Compression Test

在线全文

学校读者我要写书评

暂无评论

上海交通大学学报 2004年第Z2期38卷 8-13页

作者： Tian Sheng-li Lu Yun-de Ge Xiu-run School of Civil Engineering and mechanics Shanghai Jiaotong University Shanghai200240China School of Civil Engineering and Mechanics Shanghai Jiaotong University Shanghai200240China School of Civil Engineering and Mechanics Shanghai Jiaotong University Shanghai200240China institute of rock and Soil mechanics The Chinese Academy of Sciences Wuhan430071 China

The RMB-150B rock mechanics test system was employed to obtain the complete stress-strain test curves under confining pressures of 0-30MPa for marble samples from Ya'an ,Sichuan province. On the basis of former study and the convention triaxial pressure test results ,the complete procedures curves which described the relationships between yielding strength、 peak strength、 residual strength and confining pressure was obtained. Taking the strain softening of rock into account, the bilinear elastic-linear softening-residual perfect plasticity four-linear model was put forward in this paper on the basis of the test results and theory of plasticity. This model was adopted to describe the behaviors of marble in different phases under triaxial compression with the constitutive equation of strain softening phase as focus. The results indicated that the theoretic model fitted in well with the test results.

关键词： theory of plasticity conventional triaxial compression test constitutive model control equation linear softening bilinear elastic

Development of a new type of foam concrete and its application on stability analysis of large-span soft rock tunnel

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Central South University 2012年第11期19卷 3305-3310页

作者：王辉陈卫忠谭贤君田洪铭曹俊杰 State Key Laboratory of Geomechanics and Geotechnical Engineering(institute of rock and Soil mechanics Chinese Academy of Sciences)

The long-term stability of large-span soft rock tunnel is influenced greatly by the creep effect of surrounding *** development of a new type of foam concrete which has the property of high compressibility and low ductility was *** it was made as filling material of reserved deformation layer between the first lining and the second lining used in large-span soft rock *** effect of the new type of foam concrete was simulated as filling material of reserved deformation layer using numerical *** the comparison with the common large-span soft rock tunnel,the vault settlement and surrounding convergence are reduced by about 61% and 45%,respectively,after creep of 100 *** in the second lining,the plastic zone reduces apparently and the maximum equivalent plastic strain decreases ***,it can be found that the application of the new type of foam concrete as the filling material of reserved deformation layer can relieve the excessive force in second lining induced by rock creep,reduce its deformation and improve the stability of tunnel.

关键词： foam concrete large-span soft rock tunnel stability analysis numerical simulation

A fast explicit finite difference method for determination of wellhead injection pressure

在线全文

学校读者我要写书评

暂无评论

Journal of Central South University 2012年第11期19卷 3266-3272页

作者：白冰李小春刘明泽石露李琦 State Key Laboratory of Geomechanics and Geotechnical Engineering(institute of rock and Soil mechanics Chinese Academy of Sciences)

A fast explicit finite difference method (FEFDM),derived from the differential equations of one-dimensional steady pipe flow,was presented for calculation of wellhead injection *** with a traditional numerical method of the same equations corroborates well the reliability and rate of ***,a flow rate estimate method was developed for the project whose injection rate has not been clearly determined.A wellhead pressure regime determined by this method was successfully applied to the trial injection operations in Shihezi formation of Shenhua CCS Project,which is a good practice verification of *** last,this method was used to evaluate the effect of friction and acceleration terms on the flow equation on the wellhead *** result shows that for deep wellbore,the friction term can be omitted when flow rate is low and in a wide range of velocity the acceleration term can always be *** is also shown that with flow rate increasing,the friction term can no longer be neglected.

关键词： wellhead pressure injection pressure bottom-hole pressure fast explicit finite difference method

Dynamic design method for deep hard rock tunnels and its application

在线全文

学校读者我要写书评

暂无评论

Journal of rock mechanics and Geotechnical Engineering 2016年第4期8卷 443-461页

作者： Xia-Ting Feng Chuanqing Zhang Shili Qiu Hui Zhou Quan Jiang Shaojun Li State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences

Numerous deep underground projects have been designed and constructed in China, which are beyond the current specifications in terms of scale and construction difficulty. The severe failure problems induced by high in situ stress, such as rockburst, spalling, damage of deep surrounding rocks, and timedependent damage, were observed during construction of these projects. To address these problems, the dynamic design method for deep hard rock tunnels is proposed based on the disintegration process of surrounding rocks using associated dynamic control theories and technologies. Seven steps are basically employed:(i) determination of design objective,(ii) characteristics of site, rock mass and project, and identification of constraint conditions,(iii) selection or development of global design strategy,(iv)determination of modeling method and software,(v) preliminary design,(vi) comprehensive integrated method and dynamic feedback analysis, and(vii) final design. This dynamic method was applied to the construction of the headrace tunnels at Jinping II hydropower station. The key technical issues encountered during the construction of deep hard rock tunnels, such as in situ stress distribution along the tunnels, mechanical properties and constitutive model of deep hard rocks, determination of mechanical parameters of surrounding rocks, stability evaluation of surrounding rocks, and optimization design of rock support and lining, have been adequately addressed. The proposed method and its application can provide guidance for deep underground projects characterized with similar geological conditions.

关键词： Deep hard rock tunnels Dynamic design method rockburst In situ stress Constitutive model