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2005, 24 (16): 0-0 doi:

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2005-16期目录

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STUDY ON ROCK MECHANICS IN DEEP MINING ENGINEERING

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2005, 24 (16): 2803-2803 doi:

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The rock mechanics problems caused by the deep mining engineering are the focuses in the fields of mining engineering and rock mechanics. A lot of achievements were obtained by scholars through theoretical study，laboratory test，and in-site test. Based on the previous studies of authors，the main differences in engineering mechanics for the characters of rock mass between shallow mining and deep mining are summarized. They are complicated as follows：(1) mining environments with three“high”and one“disturbance”—high ground stress，high earth temperature，high karst water pressure，and mining disturbance；(2) five transform features of mechanical characters；(3) four changes of coal mine types；and (4) six representing types of engineering hazards. By the detailed research on the nonlinear mechanical characters of engineering rock mass in deep mining under complicated geology mechanical environments；it is pointed out that the mechanical system，which is subordinated to engineering rockmass at depth，is the nonlinear mechanical system，but not the linear mechanics system subordinated to engineering rock mass at shallow. The classic theory，methods，and technology are partly or most entirely invalid. So，it is very important to study the basic theory of rock mechanics in deep engineering.

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FAILURE CRITERION OF STRAIN ENERGY DENSITY AND CATASTROPHE THEORY ANALYSIS OF ROCK SUBJECTED TO STATIC-DYNAMIC COUPLING LOADING

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2005, 24 (16): 2814-2814 doi:

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The applicability of a failure criterion for the strain energy density of rock under static-dynamic loading is proposed. According to the analysis，critical value of strain energy density of rock is mainly determined by preceding irreversible deformation process and current environmental state；and the irreversible deformation is mainly caused by nonelastic deformation，damage and other possible intrinsic dissipative mechanisms of rock in a mechanical system；and volume deformation energy associated with hydrostatic stress effects can not be neglected on some stress states. Using mechanical model to represent the reduction of elasticity，occurrence of inelasticity deformation and effect of loading rate are proposed. On the basis of mechanical model，the critical value of strain energy density of rock under static-dynamic loading is derived. According to the catastrophe model for impact buckling of static-loading structures，a new catastrophe model for impact disturbance fragmentation of a rock system under static loading is established to analyze the rock failure under static-dynamic coupling loading ulteriorly. Finally，by using of the Instron electro-hydraulic and servo-controlled material testing machine and adopting low-cycle-index fatigue loading method，the test of red sandstone failure with medium strain rate under dynamic loading is carried out to verify the strain energy density criterion and catastrophe theory model. There is a good agreement between theoretic and experimental results.

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STUDY ON DEFORMATION AND MOTION CHARACTERISTICS OF BLOCKS IN DEEP ROCK MASS

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2005, 24 (16): 2825-2825 doi:

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The investigation of rudimental stress indicates that its magnitude has close relationship with the increment of deformation，and the dispersion of deformation module for solitude zone of tectonic groups. The capability of storage and returned energy is related with friction coefficient for the deep rock mass with tectonic level. The study on dynamic model of block indicates that the interface effects of blocks are related with the size of block and the capability of bulk deformation included in block and interface.

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EXPERIMENTAL STUDY ON VELOCITY CHARACTERISTICS OF LITHOFACIES TRANSITION ROCK MASS

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2005, 24 (16): 2831-2831 doi:

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Based on case of the colliery No.3 of Huainan coalfield in Anhui Province，the relations of sonic velocity and mechanical characteristics of the lithofacies transition rock mass are investigated by the physical modeling study and numerical simulation technique. It is found that the stress and sonic velocity are controlled by the lithofacies and its thickness. During mining processes，the existence of lithofacies transitions in rock mass changes the stress distribution of the roof in the mining faces as follows：(1) the top of lithofacies transition body is artesian flow areas；and (2) the port is located in the stress concentration position. Meanwhile，it shows that the lithofacies transition body influences the sonic velocity of the propagation in the rock mass. Upon the body，the sonic velocity propagating in the rock mass is greater than that in the below. Usually，when the sonic wave passes through the phase transition body，the sonic velocity changes to the lower，which can be used to interpret the detections some geological circumstances in the underground works and seismic exploration.

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STRUCTURAL HIERARCHY OF ROCK MASSIF AND
MECHANISM OF ITS FORMATION

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2005, 24 (16): 2838-2838 doi:

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Rock massif possesses complex structural hierarchy. Such a structural hierarchy involves very wide range of scale levels from microscopic scale level to macroscopic scale level. But until now systematic study on the mechanism of the formation of this kind of structural hierarchy does not exist. Based on the available geomechanical achievements and physical theories，the mechanism for formation of the structural hierarchy of rock massif is studied systematically. It shows that the formation of structural hierarchy is caused by the initial stage of formation of rock massif and the successive tectonic motion processes. In the initial stage of formation of rock massif，because of nonequilibrium nature of the processes and the exchanges of energy with the environment，the self-organization process and dissipative structure arise，and the self-similar fractal structures are formulated. In the view of tectonic，the earth¢s lithosphere is in nonequilibrium state because of the external actions. The energies of nonequilibrium state are supplied to the deformation and fracture of rock massif and eventually lead to the formation of dissipative structures. At different geological ages，faults of different scales are formed；and the two successively formed faults intersect with about 45°，and the scale ratio is . Because of the fractal structure in rock massif，coefficient of embedment is a natural expression of this self-similarity.

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DISCUSSION ON ROCKBURST INFLUENCED BY
REGIONAL STRESS FIELD IN CHINA

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2005, 24 (16): 2847-2847 doi:

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Rockburst influenced by the regional stress field is discussed. The correlation between rockburst and the solid tide has been discussed. The results show that rockburst occurrence has good correlation with the lunar solid tide. The correlation between rockburst and the regional natural earthquake has been analyzed；and it is found that the occurrence time of natural earthquake lags behind that of rockburst. The space distribution laws of rockburst have been considered. In the plane distribution，rockbursts are seen to locate in the earthquake-prone zones，and they are almost distributed in the earthquake zones of strong tectonic activities. There is a critical depth of rockburst occurrence in the depth distribution. The regional stress field is the one of important factors that affect rockburst occurrence.

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CONCEPTION SYSTEM AND EVALUATION INDEXES
FOR DEEP ENGINEERING

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2005, 24 (16): 2854-2854 doi:

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With the increasing of mining depth，the nonlinear dynamic mechanical phenomena，for instances，the rock blasting，gas outburst，rock rheology，and water outburst，etc.，occur with high frequency. The problems of rock mechanics caused by the deep mining engineering are the focuses in the fields of mining engineering and rock mechanics. Based on the studies of the particular geomechanical environments of deep engineering rock mass and its nonlinear mechanical characters，the conception system is put forward，which points out that the mechanical system of deep engineering rock mass is the nonlinear mechanical system，but not the linear mechanical system in shallow；and the classic theory，design method，and technology are almost entirely or partially invalid. By Using different coefficients and hazard indexes as the evaluation indexes to estimate the controlling conditions of surrounding rock masses，it can synthetically reflect the mechanical characters and engineering characters of rock masses in deep engineering.

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STUDY ON PROBLEMS OF NEAR CAVITY OF PENETRATION
AND EXPLOSION IN ROCK

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2005, 24 (16): 2859-2859 doi:

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The fundamental problems of near cavity of penetration and explosion in rock are discussed；and some development tendencies are presented. The expressions about the kinematics problems near cavity do not agree well with the stress and the deformation states. That are the reasons that considerable errors exist in the results of many scholars studies. According to the stress and deformation states near cavity in practice，the relation formulas for the kinematics of medium are deduced by using the laws of conservations of momentum and mass；and the problem of the speed of the deformation wave is solved. With the proposed relation formulae，some useful results such as the proportional conversion relation of penetration and impenetration，geometrical resemblance relation of explosion near cavity，can be clearly understood. The application results of case study show that the proposed relation formulas are practical.

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INVESTIGATION ON THREE-DIMENSIONAL MODEL OF INSTABILITY OF TRANSLATORY COAL BUMPS IN DEEP MINING

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2005, 24 (16): 2864-2864 doi:

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A study of quasi-static three-dimensional model technique which shows the typical features of translatory coal bumps in deep coal mining is introduced. The three-dimensional model is studied on the basis of the elementary theory of bumps developed by Lippmann H. This model can be used to analyze the mechanism of coal bumps occurring in the roadways with rock roof and rock floor. The friction forces in the coal seam are considered in this three-dimensional model，and the pre-critical three-zone model for pressure distribution is analyzed. A simplified elastoplastic theory is applied to analyze the translatory bumps in deep mining and some basic mechanisms of bumps are revealed. The length of secondary stress distribution region is obtained which can be used to analyze the bumps potential of coal seam. The material properties of the coal from the Zhaogezhuang coal mine are used to prove the validity of the model；and the conclusions deduced from the theory are compared with the phenomena observed in-situ. The analytical results show that the blasting mining method is the main reason causing the incident in level No.11. The geometric parameter characteristics of this three-dimensional model are analyzed and some useful information is achieved.

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DEVELOPMENT OF NONLINEAR TRIAXIAL MECHANICAL EXPERIMENT SYSTEM FOR SOFT ROCK SPECIMEN

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2005, 24 (16): 2870-2870 doi:

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In consideration of the requirements for nonlinear mechanical behaviors of soft rock at depth，the development of a new experimental system for rock mechanics is discussed，which can perform the multiple composite tests of tension-compression and tension-shearing under the conditions of different loading processes including the common function such as uniaxial tension，shearing，uniaxial and triaxial compression tests. To overcome the deficiency of the current experimental system (for rock mechanics) that cannot perform the composite tests of tension-compression，tension-shearing，and different loading or unloading process simulations，the main structures and functions of the system，the technical indexes，and the key technologies to achieve satisfactory experimental results such as reduction of friction force technology，equal-transmitting force technology，and stress-concentration elimination technology，etc.，are introduced. The presented new experiment system can provide a new method to further study of mechanical behavior of rock mass at depth.

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DESIGN PRINCIPLE FOR TRUSS-BOLT SYSTEM AND ITS APPLICATION TO DEEP COAL MINE ROOF REINFORCEMENT

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2005, 24 (16): 2875-2875 doi:

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From the view of the safety and economical problems，the controlling of stability for fractured surrounding rock roof is one of the principal problems for deep underground coal mining engineering. A theoretical design method of the truss-bolt system for reinforcing underground fractured rock roof in coalmines is presented. The mechanical analysis of the system is considered in the models for the tie-rods and inclined roof bolts as well as three upper and lower bounds. The arching actions exerted by lateral behavior of the inclined bolts in reinforcing cracked roof are analyzed. The global-resistance concerning the lateral and axial behaviors of the inclined bolts in a truss-bolt-supported roadway is examined by using the classical theory of nonlinear beam under bending and tension. Based on the mechanical models，the design formulas concerning the lateral forces of bolts，tensions of tie-rod in truss system are given；and the reinforcement behaviors have been proposed. The analytical formulas for both lower and upper bounds for truss pre-tightening forces are put forward. Furthermore，the analytical equations for designing axial forces and dimensions of bolts in the system are presented. In order to make the truss-bolt design intelligent and effective，computer-aided design (CAD) software codes for coalmine truss-bolt reinforcement are developed. A case study for Suncun coal mine roadway supporting engineering is presented. This coalmine is considered as one of the deepest underground coal mining projects with buried depth of 1 310 m in China. The in-situ tests show that the fractured roof is reinforced effectively；and the validity of study is proved.

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STABILITY ANALYSIS OF WELLBORE BASED ON ANISOTROPIC STRENGTH CRITERION FOR DEEP JOINTED ROCK MASS

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2005, 24 (16): 2882-2882 doi:

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In present engineering design，rock mass is simply treated as isotropic material and their strength parameters is given by decreasing those of intact rock through joint connectivity，which is introduced to reflect the integrity of rock mass separated by joints. This method may be acceptable for shallow rock engineering. But for deep rock engineering，with the increase of exploit depth，the anisotropic properties of rock mass become stronger and should be considered. In the previous studies，by defining joint connectivity as a scalar valued ODF(orientation distribution function) in microplanes，and based on Mohr-Coulomb failure condition and anisotropic strength criterion for jointed rock mass，a two-order fabric tensor of joint connectivity was proposed. In the study，the anisotropic criterion for jointed rock mass is presented briefly. The elastic stability problems of wellbore are studied according to the anisotropic strength criterion. When the anisotropic strength of rock mass is considered，the analysis show that drilling along the maximum in-situ stress may not be always safer than that along other direction at a given mud pressure.

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STUDY ON MECHANISMS AND TECHNOLOGY FOR BOLTING AND GROUTING IN SPECIAL SOFT ROCK ROADWAYS UNDER HIGH STRESS

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2005, 24 (16): 2889-2889 doi:

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With the large-scale exploitation performance and deep mining，the support problems of special soft rock roadways under high stress become increasingly serious. Based on the analysis of present supporting situation for special soft rock roadways under high stress，the bolting and grouting support systems to solve supporting problems for special soft rock roadways under high stress are discussed. Experiments in the mine indicate that bolting and grouting supports can keep the stability of special soft rock roadways under high stress，and construction velocity is increased and the supporting cost can be reduced. Therefore，it shows that the bolting and grouting support systems have a brilliant prospect in practice.

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STABILITY ANALYSIS OF MINED-OUT AREAS INFLUENCED BY BLASTING VIBRATION WITH FLAC3D

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2005, 24 (16): 2894-2894 doi:

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For the reason that Changba lead-zinc mine is severely destroyed by disordered mining，the numerical analysis of mined-out areas under blasting vibration is carried out with FLAC3D . Two different measured velocity time-dependent curves are selected as blasting vibration input according to the in-situ test data；and static calculation and dynamic calculation are carried out，respectively. The analytical results show that the maximum displacement of surrounding rock is 4.75 mm after mined-out areas are excavated，while the maximum displacement of surrounding rock increases to 5.47 mm after the blasting dynamic loading is applied，and amplitude of increasing displacement is proportional to the velocity of blasting vibration. The shape of vibration wave influences the variation of displacement distribution for surrounding rock. When the blasting vibration dynamic loading is applied，the second redistribution of stress field of surrounding rock occurs；and the distribution area of plastic zone is expanded obviously. The foot of the right open slope above the mined-out area is also influenced as well. The analytical results are accordant with the observed results. Several suggestions to avoid instability and subside of mined-out areas induced by blasting vibration are brought forward.

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COUPLING MODEL OF STRESS-DAMAGE-FLOW AND ITS APPLICATION TO THE INVESTIGATION OF INSTANTANEOUS SEEPAGE MECHANISM FOR GAS DURING UNLOADING IN COAL SEAM WITH DEPTH

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2005, 24 (16): 2900-2900 doi:

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On the basis of basic theories of gas flow and coal deformation，the coupled gas-rock model for investigating the failure process of coal-rock is established by introducing the related equations governing the evolution of stress，damage and gas permeability along with the deformation of coal and rock. Implemented with rock failure and process analysis code (RFPA)，this model can be used to capture the evolution of gas permeability in coal seam at great depth and the distribution of gas pressure around the drilling hole，and explore the instantaneous seepage mechanism of gas flow. From the simulated results，it can be found that the coal seam，located around 67 m above the excavated seam，is under unloading state and its gas permeability dramatically increases about 2 000 times as that excavated in underlying coal seam，and the size of the unloading region is around 70 m in diameter. The simulated results are in good accordance with the in-situ results. Therefore，it is safe to say that this numerical tool is of significance in both theory and practice to investigate the evolved mechanisms of gas permeability and gas drainage.

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DISCUSSION ON FORM OF ROCK COMPRESSION AND SHEAR
FRACTURE NUCLEUS OF EARTH¢S CRUST

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2005, 24 (16): 2906-2906 doi:

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The shape equation of KⅠ，KⅡ，KⅢ for rock compression and shear fracture nucleus of the earth¢s crust，when the coefficient KⅠ is less than 0，is given. The shape and character of KⅠ，KⅡ for compression and shear fracture nucleus with the shape of leaf，and KⅠ，KⅢ for compression and torsion fracture nucleus with the shape of bud are analyzed. Compression and torsion of direct shear fracture test and rupture state of marble samples are introduced. The rock rupture state can be seen in the microcosmic photo of the notched area of compression and shear fracture samples before failure. The results agree well with the theoretic analytic results. The extension length of rock compression and shear fracture nucleus of the earth's crust is discussed，and it is verified by in-situ findings of geological investigation.

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EXPERIMENTAL STUDY ON PROPAGATION OF DYNAMIC CRACKS UNDER BLASTING LOADING

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2005, 24 (16): 2912-2912 doi:

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It is an effective new method to make further analysis of crack propagation for blasting fracture with dynamic caustics. Using a plexiglass sample and by means of shadow optical method of caustics，the different features of dynamic variation in stress (or strain) field，plastic area，and nucleation zone (shadow area) during loading and unloading are studied. The propagation，termination，and mode of blasting cracks are presented. An accurate termination tenacity value is achieved；and preliminary cracks are extended rapidly under blasting stress wave. A full of strain energy accumulates in the top of blasting crack；and the mode of caustics of latter crack is close to the common dynamic caustics. The majority of blasting cracks is a process of unloading fracture.

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STUDY ON FAILURE BEHAVIOR OF ROCK UNDER COUPLING EFFECTS OF TEMPERATURE AND CONFINING PRESSURE

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2005, 24 (16): 2917-2917 doi:

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Based on the background of deep mining，some conclusions related to effects of temperature and confining pressure on behaviors of deformation and failure of rocks at depth are reviewed. Regarding the process of rock yield deformation and failure as a process of energy release and energy dissipation，a failure criterion of deep rocks subjected to coupling effects of confining pressure and temperature is proposed according to the principle of least energy consumption. With a clear physical meaning，this failure criterion shows that if both the plastic dissipation energy and heat conduction dissipation energy caused by temperature gradient in rocks reach to a critical value，the rock will lose its load carrying ability.

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ACOUSTIC BOREHOLE TELEVIEWER WITH HIGH RESOLUTION
AND ITS APPLICATION TO DEEP FORMATION FOR GEOLOGICAL DISPOSAL OF NUCLEAR WASTE

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2005, 24 (16): 2922-2922 doi:

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Acoustic borehole televiewer (BHTV) logging is the first geophysical approach to obtain the intuitionistic image of borehole wall. New generation BHTV is characterized with high accuracy，resolution and high logging velocity for the advanced technology of focused ultrasound beam and digital recording and digital data process are adopted. It is one of the most direct and effective methods to detect fracture in boreholes. The main advantages of the BHTV are of high resolution and full 360-degree coverage of the borehole circumference from which the character，relation，and orientation of structural planar features can be defined. Simple introduction of the acoustic imaging method is presented，and its application and integrated studies on pre-siting and site characterization for deep geological disposal of high-level radioactive waste are described. The borehole images，three magnetometer coordinates，and two inclinometer coordinates of each point of borehole wall are obtained by using BHTV. Based on this borehole information，location，size and orientation of fractures that intersect the borehole are determined. The calculation of borehole deviation is performed；and the rock cores taken from borehole are oriented in the laboratory. The extension of joints/fractures and faults surrounding the borehole is assessed. Therefore，it is considered that BHTV is a useful tool to detect the joints and fractures in the deep geological formation. But as a geophysical approach，limitations of this tool in practice should be considered.

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INFLUENTIAL LAWS ON STRATA AND GROUND MOVEMENT OF FACE-SEPARATED PILLARS AT A GREAT DEPTH

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2005, 24 (16): 2929-2929 doi:

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A phenomenon of sub-critical mining subsidence appears in Jiaoping mining area in Shaanxi Province，which is under the conditions of great mining depth，thick seam and fully-mechanized top-coal caving. By similar material tests，the relationships of ground movement with the width of working face，the size of face-separated pillar，and the lithologic characteristic of overlying strata are studied. The main characters of rock masses movement are revealed. The achieved results prove that the face-separated pillars with a definite width can effectively control ground subsidence. It will provide references to those mines with similar conditions in Jiaoping mining area.

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CHAOTIC PREDICTION METHOD OF ROCK MASS DEFORMATION
IN DEPTH

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2005, 24 (16): 2934-2934 doi:

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The deformation behavior and the application of chaotic method for the stability analysis of the rock mass engineering in depth are summarized. For the measured displacement time series of rock mass engineering，the procedure for calculating the largest Lyapunov exponent is given on basis of phase space reconstruction. Linear and nonlinear chaotic prediction methods are represented for the rock mass displacement. Thus，the chaotic analytic method is set up for the prediction of the measured displacement time series of rock mass engineering. The analysis of the 255 m main transport roadway damaged in Linglong gold mine is considered as an example. At first，the damaged situations of the 255 m main transport roadways are simply presented. Then，for the measured convergent displacement time series of the 255 m main transport roadway，the interpolation method is adopted；and an equal interval displacement time series is obtained. The results show that the largest Lyapunov exponent is 0.05 based on phase space reconstruction. Finally，it is separately predicted by the method of equidistance in near neighbor and that of the largest Lyapunov exponent prediction，and the predicted displacement values are ideal compared with the measured displacement values.

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A METHOD OF ROCK MASS STABILITY ANALYSIS BASED
ON SPATIAL AGENT

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2005, 24 (16): 2941-2941 doi:

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The stability of rock mass is a key issue in ensuring the safety of mine. Because the rock masses are situated in a complex geological environment with complicated components and structures，hydrogeological conditions，mining process etc.，its deformation presents the behaviors of complicated nonlinear and dynamic characteristics. Therefore，these complex behaviors of the rock mass should be described by the method of spatial agent model based on knowledge fusion technology. It could be used to analyze the stability of rock mass，and to study the adaptive behaviors of a complex system when external environment of the rock mass changes. The stability of rock mass is described in detail by the structure and property，the mechanism of self-study，and the integrated behaviors of the spatial agent. Finally，it is verified by the related theory and case study of a coal mine.

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PRELIMINARY ESTIMATION OF CO2 STORAGE CAPACITY
OF COALBEDS IN CHINA

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2005, 24 (16): 2947-2947 doi:

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Geological storage is an effective means of reducing anthropogenic atmospheric emission of CO2 to alleviate the worsening global climate change. CO2 storage in coalbeds can effectively reduce the emission of CO2，and at the same time，it can enhance the recovery of coalbed methane to reduce the cost of CO2 geological storage. The CO2 molecules are absorbed on the surface of coal matrix and the methane molecules can be released when CO2 is injected into the coalbeds. The absorbed CO2 on coal matrix can be kept stably in coalbeds for geologic time. There is a huge storage capacity for CO2 in coalbeds in China for the wide distribution and abundant resources of coal. Putting CO2 into coalbeds should be the prior choice for its security and safety. According to the latest prospecting data of coal and coalbed methane resources in China and the replacement ratio between CO2 and CH4 in the coal with different ranks，it is estimated that the CO2 storage can be performed from depth of 300 m to 1 500 m in the main coalbed methane basins in China. The total recoverable coalbed methane resources will approach to 1.632×1012 m3 if the CO2-enhanced coalbed methane recovery(CO2-ECBM) technology is utilized，and the CO2 storage capacity in coalbeds is about 120.78×108 t，which is about 3.6 times as the total CO2 emission of China in 2002.

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FAILURE STRAIN OF BRAZILIAN DISC SAMPLES OF MARBLE UNDER DYNAMIC SPLIT TESTS

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2005, 24 (16): 2953-2953 doi:

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The strain-based strength criteria are of increasing significance for brittle materials. In order to study the laws of failure strains under dynamic tension，a series of Brazilian disc and flattened Brazilian disc(FBD) samples of marble under the dynamic split tests are performed with a wide range of strain rates using split Hopkinson pressure bar(SHPB) of 100 mm in diameter. The relationship between the failure strain and the size of samples，the projectile speed，and the strain rate，are discussed；and some useful results are obtained. The failure strains of all types of samples in different projectile speeds are achieved with strain gauges stuck on the center of the samples；and the test results indicate that the failure strain increases with the increase of the projectile speed. In certain range of the projectile speed，the failure strain increases remarkably. But when it is out of this range，the failure strain increases slightly. The relationship between the failure strain and the size of samples is notably affected by the projectile speed. However，when the strain rate is low，the failure strain will increase remarkably，especially for FBD which has less scatter；when the strain rate is high，the failure strain increases slightly and results of all types of samples are scarcely scattered. Compared with Brazilian disc，the FBD has larger bearing capacity and higher failure strain in low projectile speed. With the increase of projectile speed，the trend of FBD vanishes gradually；and when the projectile speed is high，its failure strain is even less than that of the Brazilian disc.

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P-WAVE AZIMUTHAL AVO ANALYSIS OF FRACTURE DETECTION IN COALBED AND ITS APPLICATION TO ENGINEERING

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2005, 24 (16): 2960-2960 doi:

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Fractures will exert great menace to the safe production of coal fields. The fracture detection of coalbed is an important problem in the development of many coalfields. Due to the overlying strata pressure, horizontal fractures and low-angle fractures of the stratum almost disappear. The characters of P-wave azimuthal anisotropy are mainly caused by high-angle fracture and vertical fracture of the stratum；and the azimuthal anisotropy of P-wave reflects the situation of fracture of underground medium. Especially，P-wave azimuthal amplitude variation with offset (AVO) is sensitive to fracture. Therefore, the analysis of P-wave azimuthal AVO can be used to delineate fracture patterns and investigate their properties. The theory and method based on P-wave azimuthal AVO analysis are applied to the P-wave seismic data in some mining area of Huainan coalfield. The fracture distributions of some coa beds in this area are achieved. The results of predicted fracture agree well with the in-situ data；and the proposed method is proven to be successful.

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MATHEMATICAL MODEL AND NUMERICAL SIMULATION OF COAL-BED METHANE PERCOLATION FLOW EQUATION
CONSIDERING SLIPPAGE EFFECTS

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2005, 24 (16): 2966-2966 doi:

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Under the depth of about one kilometer in the deep mining，the pressure of the coal-bed is considerably high and the permeability of the coal-bed is comparatively low，in which the porous media is regarded to be highly compacted. Considering the percolation in this pre-pressing porous media，the slippage effects are remarkable. The model of coal-bed methane percolation equation under high pressure condition，which considers the slippage effects of coal-bed methane，is proposed；and finite element method(FEM) is employed to calculate the numerical value of mathematic model. The pressure gradient calculated by FEM，which is influenced by slippage effects under high pressure condition，is compared with that of mathematic model. The foundation of mathematics model for coal-bed methane slippage is established to study the nonlinear percolation problems of coal-bed methane. The simulated results can provide significant references to the evaluation of the output of the coal-bed methane with low permeability under high pressure condition.

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TWO-PHASE MISCIBLE DIFFUSION MODEL AND ITS SOLUTION BETWEEN GAS IN GOAF AND ATMOSPHERE

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2005, 24 (16): 2971-2971 doi:

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The model of gas effusion and air exchange in inhomogeneous goaf was established based on two-phase miscible gas seepage-diffusion equation. The model is solved by means of upwind Galerkin numerical method，and the basic fluid mechanics principle of the gas transport and distribution is described by means of visualization way. On the basis of mechanical disposal，the gas effusion in the goaf with gas-tight roof and floor is treated as two-phase gas miscible flow；but the calculation of the flow pattern (velocity field) is solved by regarding it as a seepage problem of incompressible gas. So it can avoid the error and distortion from incompressible gas seepage-diffusion model in calculating gas distribution because of super saturation solution in the result. The gas source in goaf is described by negative exponential attenuation function. An example provided in the case of wind is increased，which shows the dynamical balance feature between the air pressure in working face and gas pressure in the goaf. Compared with the result calculated as single-phase flow，the gas distribution results between them are almost the same when the speed of air is relatively high，if not，there is a large difference between the results. The critical air speed when the difference appears in the example is 0.091m/min，but the gas distribution is significantly different in the deep part of the goaf.

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EXPERIMENTAL STUDY ON INFRARED THERMAL IMAGE FOR FAILURE PROCESS OF GRANITE WITH FRACTURE

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2005, 24 (16): 2977-2977 doi:

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The changing rule for infrared thermal image boding of the rock with crack is essential for the geotechnical engineering，especially for the underground engineering. In order to study the rule，infrared thermal images for the failure process of rock with fracture are carried out. The size of the rock sample is 20 cm×10 cm×2 cm with a crack of 45°to the horizontal direction at the center and with the length of 2 cm. Considering the fact that sample will effect the results of the observation for infrared thermal image during the experiment，the laminated granite sample is used to replace the cylinder or cuboid sample. The achieved results under uniaxial compression indicate that intensity of the microruptures has close relation with the thermal effects. When the main fractures happen，there is a strip of high temperature that will appear at the destructive local area. During loading process，the abnormality of infrared temperature has three kinds of behaviors as follows：(1) temperature falls first and rises just before fracture；(2) temperature rises and falls alternately，and rises before the fracture；and (3) temperature rises slowly at first，and then rises quickly before the fracture appears. Even for the same rock sample，the behaviors of the infrared phenomenon may be different during failure process.

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COMPREHENSIVE STUDY ON PREDICTION OF ROCKBURST IN DEEP AND OVER-LENGTH HIGHWAY TUNNEL

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2005, 24 (16): 2982-2982 doi:

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Cangling tunnel in Taizhou¾Jinyun highway，with a depth about 768 m and with a length about 7.6 km，will be the deepest and longest tunnel in Zhejiang Province after construction. Rockburst is a serious problem during the tunnel excavation. For the prediction of rockburst，physico-mechanical properties of the rock masses were tested in the laboratory；and the in-situ stress state in the engineering area was measured and analyzed. Then，the rock masses along the tunnel were classified on the basis of local geological investigation. A mechanical model was developed to express the actual conditions of the engineering area according to properties of the rock masses，focal mechanism solutions，and in-situ stress state. The in-situ stress field of the engineering area was regressed by 3D finite element method (FEM) by using in-situ measured stress. The calculated results were applied to numerical analysis of the stress distribution in rock masses around the tunnel. Finally，the probability and intensity of rockburst along tunnel were predicted according to four different rockburst prediction models developed by predecessors on the basis of calculated stress distribution around the tunnel and uniaxial compressive strength of the rock masses.

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UNIFORM EXPERIMENTAL STUDY ON PERMEABLE
COEFFICIENT OF DEEP AQUIFER

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2005, 24 (16): 2989-2989 doi:

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By experiment setting that is developed by the authors and based on the theory of uniform design，uniform experimental study on permeable coefficient in 19 samples from the aquifer under high stress indicates that the permeable coefficient and effective stress can be expressed by damped exponential function. The study also shows that the regression coefficients are synthetically influenced by characteristic grains ， and ，and characteristic parameter and the porosity . Both the experimental study and the variance analysis identify that the value of permeable coefficient under zero stress is determined by n and ；and the effective influencing coefficient of stress is controlled by ， and ，especially by . The larger the value of is the smaller the values of and are，the larger the values of effective stress influencing coefficient are. This research points out that the law and value of permeable coefficient in deep aquifer can be predicted by characteristic grain，characteristic parameter，and effective stress of soil.

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RESEARCH ON EFFECTS OF PERMEABILITY PRESSURE ON SLOPE STABILITY DURING REGULATING WATER LEVEL IN THREE GORGES RESERVOIR

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2005, 24 (16): 2994-2994 doi:

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Based on analyzing rock and earth structure in unconsolidated slopes，the style and intensity of permeability pressure in slopes during regulating water level in the Three Gorges Reservoir are discussed. Due to many unsolved boundary problems in simulating variation of water flow in slope，a new formula for calculating permeability pressure in slope is proposed，by studying on permeability pressure in certain boundary conditions with one-dimensional seepage theory. With this formula variation of phreatic surface and permeability pressure in Beimengou landslide in the Three Gorges Reservoir area，are calculated. The results show this formula is reasonable and effective for certain boundary；and it can provide a basis for appraising the stability condition of slopes and designing control projects.

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DISCUSSION ON“A STUDY ON THE CRITICAL DEPTH OF DEEP ENTRY WITH CATASTROPHE THEORY”

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2005, 24 (16): 2998-2998 doi:

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REPLY TO “DISCUSSION ON ‘A STUDY ON THE CRITICAL DEPTH OF DEEP ENTRY WITH CATASTROPHE THEORY’”

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2005, 24 (16): 3001-3001 doi:

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