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2003, 22 (04): -0 doi:
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COUPLING MODEL OF UNDERGROUND GAS-STORAGE
CAVERNS AND ITS APPLICATION IN ENGINEERING

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2003, 22 (04): -515 doi:
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[PDF 488 KB] (931)

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According to the principles of underground gas-storage caverns with water curtain，variational principle in LPG coupling system of stress field，seepage field and gas-storage field of underground gas-storage caverns is established and its FEM program is developed. The programs are applied in engineering，and the numerical model is proved to be reasonable and credible.

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NUMERICAL SIMULATION OF LOCALIZED
DEFORMATION FIELD FOR ROCK IN PLANE STRAIN STATE

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2003, 22 (04): -521 doi:
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[PDF 223 KB] (1166)

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Deformation field in relation to shear strain localization，such as shear strain rate，volumetric strain rate，velocity and displacement for rock material undergoing elastic and strain softening stage，was studied by FLAC3D. A reprocessing code programmed by FISH was developed to show the distributed shear strain and displacement in the form of three-dimensional curved surface，which contributed to understanding of strain localization phenomena. The inclination angle of shear band and its width increase as dilatation angle is increased. The extent of localized deformation decreases as dilatation effect is considered. The increase of the inclination angle of shear band and its width has an opposite influence on stress-strain curve of specimen after localization occurs. Two conjugate shear bands divide the specimen into four small blocks，which have properties of movement of rigid body. In every small block，the displacement field is uniform，and in the edge of the shear band the field has large spatial gradient. The location of shear strain rate localization coincides in position with the location of volumetric strain rate，which is the actual failure zone of rock.

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3D ELASTO-VISCO-PLASTIC HIERARCHICAL BLOCK ELEMENT METHOD FOR ROCK MASS

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2003, 22 (04): -525 doi:
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[PDF 430 KB] (943)

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A three-dimensional elasto-visco-plastic hierarchical block element method for rock mass is developed. First，the three-dimensional hierarchical shape functions and the elasto-visco-plastic constitutive model are adopted in the covering element of each block element. Then，the equilibrium equations of rock masses are deduced，based on the virtual work principle. Finally，the numerical integration schemes and the treatment of boundary conditions are discussed. Two numerical examples are studied. The results are in good agreement with the analytical and FEM solutions，and the new method is proved to be accurate and efficient. The proposed method can be widely used in deformation and stability analysis for rock mass due to the simple pre-processing and high accuracy.

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ANALYTICAL SIMULATION OF FAR REGION IN THE STRUCTURE-FOUNDATION MEDIUM INTERACTION ANALYSES

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2003, 22 (04): -532 doi:
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[PDF 377 KB] (763)

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An analytical modeling method of infinitely far region in the structure-foundation medium interaction analyses is proposed in this paper. This method can reflect the characters of infinite medium without increase in computational cost and is favorable for the engineering application.

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THREE-DIMENSIONAL ANALYSIS ON CONCRETE-LIKE MATERIALS WITH INNER SOFTENING BAND METHOD

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2003, 22 (04): -537 doi:
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To research the first kind of fracture modes in concrete solid，a new method with inner softening bands in element is adapted in this paper. The formulas needed in the three-dimensional model are deduced, including the stress and displacement on the fracture surface. The nodes with the effect of fracture are also discussed. Based on the virtual work principle，the equilibrium equations of FEM considering the effect of fracture are established. Numerical results are listed to demonstrate the accuracy of the program and the rationality of the proposed method.

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IMPROVED PROGRAM OF AUTOMATED GRID
FOR THE NEED OF MODEL TEST MEASURMENT

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2003, 22 (04): -543 doi:
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[PDF 324 KB] (1058)

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The mark spots are arranged on model surface by automated grid，and displacement field can be obtained by analyzing displacements of spots. When the model test is made，the model is often excavated. When model is excavated，the mark spots are removed. This causes big trouble in computer automatic recognition and handling. Program of automated grid is compiled again. Model test is made by automated grid，and images are handled by the program improved. Results show that the program woks well and can meet the practical needs.

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EFFECTS OF CHEMICAL EROSION ON UNIAXIAL COMPRESSIVE STRENGTH AND MESO-FRACTURING BEHAVIORS OF ROCK

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2003, 22 (04): -547 doi:
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[PDF 363 KB] (1369)

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Erosive effects of water chemistry on the uniaxial compressive strength of rocks are studied according to the meso-mechanical experiments，and the microscope images and entire images of the meso-fracturing process are obtained. The meso-fracturing behaviors and erosive mechanism of rock are analyzed under chemical erosion. Therefore，the results can be used as scientific references to setting up the mechanical model of the chemical damage of rock and evaluating the long-term stability of the rock and soil engineering.

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INTERACTION OF FRICTIONAL CRACKS IN
ROCK-LIKE MATERIALS

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2003, 22 (04): -552 doi:
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[PDF 229 KB] (1093)

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An approximate method of interaction of multiple cracks is extended to the study on interaction of frictional cracks in rock-like materials. The cases of two inclined collinear cracks and a pair of offset parallel cracks are discussed in detail. The results obtained show that interaction between cracks could produce either an enhancement or a shielding effect on the stress intensity factors depending on the positions of the cracks. The method can be used to study further the mechanism of propagation and coalescence of cracks in rock-like materials.

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STUDY ON NONLINEAR SEEPAGE OF ROCK OF LOW PERMEABILITY

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2003, 22 (04): -556 doi:
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Results of many experiments have shown that fluid flow in low permeability rock is nonlinear. The reasons are studied in this paper. Mathematical model describing fluid flow in low permeability rock is obtained theoretically. Critical condition of nonlinear flow is also given. Comparison with the experiment results shows that the mathematical model is verified.

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STUDY ON PERMEABILITY OF ROCK MASS BASED ON WATER PRESSURE TEST DATA BY USING FRACTAL THEROY

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2003, 22 (04): -562 doi:
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[PDF 166 KB] (1204)

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The data from conventional water pressure test is analyzed by using R/S method and the fractal dimension of rock mass permeability is obtained. The fractal features of permeability of rock mass caused by different rock behaviors and constructions is discussed by analysis of the data from water pressure tests in different hydroelectric projects.

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DESIGN OF ROCK POINT LOAD TEST METHODS FOR RESEACH OF SATURATED UNIAXIAL COMPRESSIVE ROCK STRENGTH

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2003, 22 (04): -566 doi:
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Two kinds of point load test methods for obtaining saturated uniaxial compressive rock strength are designed，and the related test results are compared with compressive strength test results. The advantages of the two methods are summarized，which is important for application of rock point load test in practice.

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FORMULAE FOR MEASURING BULK DENSITY AND WATER CONTENT OF SPECIMEN IN THE TRIAXIAL TEST USING TWO
TYPES OF g -RAY

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2003, 22 (04): -569 doi:
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[PDF 217 KB] (1181)

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As a result of non-destructiveness and quick acting，gamma rays are widely applied to quick and undisturbing measurements. As we all know that bulk density and water content of a specimen will simultaneously change when it is under the action of force and water. Therefore，two type of isotope and two kinds of gamma rays are adopted in measuring bulk density and water content of the specimen at the same time. Based on the achievements of nuclear physics， the equation is deduced for measuring bulk density and water content of specimen in the triaxial test using two isotopes and two kinds of gamma rays.

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STUDY ON PREDICTION OF WATER-INRUSH FROM COAL FLOOR
BASED ON CUSP CATASTROPHIC MODEL

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2003, 22 (04): -573 doi:
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When the water-pressure in floor stratum exceeds the floor strength after coal mining，the floor collapses and water-inrush from coal floor occurs. This phenomenon can be tackled by catastrophe theory. In the paper，a cusp catastrophic model of water-inrush from coal floor is established，and water-inrush mechanism of coal floor destruction is analyzed. The ratio of water pressure to stress， can be derived from the model. When ＞1，water-inrush from coal floor may occur. When ＜1，no water-inrush from coal floor occurs. The analysis of actual examples indicates that a cusp model is appropriate to describing the development of the ratio of water pressure to stress，and the prediction of water-inrush from coal floor is pertinent.

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EXPERIMENTAL STUDY ON DEFORMATIONAL MODULUS
OF FRIABLE ROCK DURING COMPACTION

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2003, 22 (04): -578 doi:
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Through the experimental research on the compaction of friable rock block，the relationship among deformation modulus，axial stress and strain were obtained. The result of this experiment reveals that the tangential modulus is exponential with axial stress，and varies with rock block size and rock property. The secant modulus is linear with axial stress. Both the tangential modulus and secant modulus are exponential with axial strain. The conclusion of this research is valuable to analysis of deformation mechanism of friable rock compaction.

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PREDICTION OF VISCO-ELASTIC PROPERTY OF
UNIDIRECTIONALLY JOINTED ROCK

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2003, 22 (04): -582 doi:
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A homogenization-based method for predicting the visco-elastic property of undirectionally jointed rock is presented，and the explicit formulae for predicting the visco-elastic relaxation modulus are obtained. After Laplace transforming the governing equation of the visco-elastic problem of jointed rock，the dependent relation of the Laplace transformation of the effective relaxation modulus of jointed rock with the joint form is derived by applying the homogenization method in phase space. Then，the effective relaxation modulus is obtained from the inverse transformation. Numerical example is presented in the end of this paper.

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STABILITY ANALYSIS AND MONITORING FOR TUNNEL IN LOOSE SOILS DURING CONSTRUCTION

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2003, 22 (04): -589 doi:
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[PDF 552 KB] (1485)

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This paper deals with stability of the Sangzhouling Tunnel construction. First，FEM is used to analyze the stability of the shallow tunnel section，and soil nails are used to improve the upper soils. Second，monitoring work is done deliberately. The collapse of local face is predictsed successfully. The monitoring results show the influence of the aguifers in the loose surrounding rock on the stability.

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ELASTO-PLASTIC AND STOCHASTIC MEDIUM METHOD AND APPLICATION IN ANALYSIS OF GROUND DISPLACEMENT AND STRESS CHANGE DUE TO TUNNEL CONSTRUCTION

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2003, 22 (04): -596 doi:
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[PDF 312 KB] (886)

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In the application of stochastic medium theory，it is assumed that ground movement process is of the property of stochastic process，and the ground movement and deformation due to tunnel excavation can be calculated. In the application of elasto-plastic medium theory，the rock and soil are assumed to be elasto-plastic medium, and the stress change due to tunnel excavation can be calculated，too. The comparison between the field measurements and the calculated results shows the validity of the proposed method.

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THEORETIC AND TESTING ANALYSIS OF SOIL DEFORMATION IN THE AREA OF DISTURBANCE CAUSED BY PIPE-JACKING

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2003, 22 (04): -601 doi:
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[PDF 356 KB] (1424)

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According to site monitoring and test results，the mechanism and behaviour of soil deformation induced by large-scale pipe-jacking construction are analyzed and a significant mechanism theory is presented. With soil compactedness change taken into account，Peck’s subsidence formulation (RPSF) is revised，and the results calculated by RPSF are in a good agreement with that by site monitoring.

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RESEARCH ON CONSTRUCTION MECHANICS OF
OVERLAPPING TUNNELS

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2003, 22 (04): -606 doi:
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[PDF 219 KB] (1006)

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Overlapping tunnels have emerged in facilitating the underground space utilization. The initial stresses in ground will be changed by the first excavation，and the ground stiffness is no longer symmetrical to the vertical single tunnel axis because of the adjacent lined tunnel in the ground. The construction of the second tunnel has effect on the first constructed tunnel. ANSYS program is used to analyze three typical sections of overlapping tunnels of the first-phase of the project of Shenzhen metro. Analysis results show that the settlement of surface and arch and the stability of soil between two tunnels are difficult to control，and the settlement of upper tunnel occurs easily.

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IN-SITU STRESS MEASUREMENT IN ROCKMASS OF ERLANG MOUNTAIN HIGHWAY TUNNEL

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2003, 22 (04): -611 doi:
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[PDF 257 KB] (1127)

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Through the in-situ stress measurement by borehole overcoring technique and Kaiser effect method，it is found out that the general space stress state of rockmass in the famous，deeply-lying and especially long Erlang mountain highway tunnel，belongs to the potential strike-slip type. The measured in-situ stresses in the middle part of the tunnel are generally very large with the major principal stress of 35.3 MPa. So during the construction process，the problems of high in-situ stress and rockburst have to be taken into account.

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PRINCIPLE AND APPLICATION OF 3D GEOSTRESS MEASUREMENTS BY HYDRAULIC FRACTURING TECHNIQUE IN A VERTICAL BOREHOLE

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2003, 22 (04): -615 doi:
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[PDF 239 KB] (873)

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According to the features of vertical borehole，the principle and method of 3D geostress measurements by hydraulic fracturing technique in a vertical borehole are advanced，and calculating formulas for data processing are presented through an example.

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APPLICATION OF GEO-DYNAMIC DIVISION METHOD
IN PREDICTION OF COAL AND GAS OUTBURST REGION

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2003, 22 (04): -621 doi:
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[PDF 307 KB] (979)

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Geo-dynamic division method based on the theory of plate tectonics is a new way to conduct region prediction of mine dynamic phenomena. With the cost being low，implementation simple，the method has wide application prospect. This paper has briefly introduced the geo-dynamic division method and its application in Pingdingshan mining area.

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NUMERIC SIMULATION ON RAINFALL INFILTRATION ON ROCK SLOPE

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2003, 22 (04): -625 doi:
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The mathematical model of rainfall infiltration on the rock slope and the numerical simulation method for this model is discussed. Based on this，the system of nonlinear equations in saturated-unsaturated seepage model is researched. The solution method and process of the system of nonlinear equations with Picard iteration method is given. The pattern of rainfall infiltration on the rock slope is analyzed. The variation of matrix suction，the formation and development of transient saturated zone，and the distribution and variation of transient water pressure in the process of rainfall infiltration on the rock slope are described. All the stages of rainfall infiltration on rock slope in a given open pit mine is simulated with the presented method.

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RESEARCH ON EXPERIMENTAL METHOD FOR IDENTIFICATION OF
ROCK BODY WITHIN SLIDING MASSES OF LANDSLIDE

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2003, 22 (04): -630 doi:
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[PDF 261 KB] (905)

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It is difficult to distinguish the strata outcrop and rock mass within sliding masses of landslide. A new method is put forward to determine the rock mass within sliding masses by combined analysis of macrogeological features and microcosmic structure characteristics. The method is applied in the Three Gorges Project successfully.

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DISCUSSION ABOUT THE STABILITY OF ROCK MASS
FREE FACE ON THE TIP OF ROCK-SOCKED
PILE IN CARST REGION

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2003, 22 (04): -633 doi:
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The key problem of karst foundation is not the foundation strength itself but the foundation stability，especially the stability of the free face of rock mass on the pile tip. Though there are semiquantitative analysis and appraisement，and dead load test for deep well，it is found that there are still some theoretical irrationalities in the current geoengineering. The authors believe that if the structure of the rock mass is comparatively intact and the load of the tip of pile is less than the bearing cpacity of the batholith of the rock mass in the pile tip，the free face will be stable. Owing to this idea，there will be many economical benefits for engineering.

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APPLICATION OF STAGED BURN-CUT
IN SHAFT BLASTING IN LIMESTONE

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2003, 22 (04): -636 doi:
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[PDF 190 KB] (1004)

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Field experiments of vertical staged cutting with a duplex-triangle，with a duplex-square，and with millisecond delay in a hole are reported in this paper. It is found that the staged cut with duplex-square has the best blasting effect in trial shafts sinking. This experimental result is analyzed with the existing achievements of rock dynamics. In addition，our experiments also indicate that the best depth of blast hole is close to shaft radius.

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INFLUENCE OF DIFFERENT KINDS OF HOLE CHARGING
STRUCTUE ON EXPLOSION ENERGY TRANSMISSION

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2003, 22 (04): -641 doi:
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[PDF 232 KB] (1103)

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Transmitting from one material to another，wave will reflect and refract in the interface due to different wave impedance matching. Wave energy will reflect and refract，too. The energy along with reflected wave into the primary material is called reflected energy，and the energy along with refracted wave into another material is called refracted energy. Based on the theory of the transmission of reflected wave and retracted wave at interface，the transmission (including reflection and refraction) of explosion energy is analyzed and the calculating method on the rate of reflection and refraction of explosion energy and the relationship of the best impedance matching between rock and explosive are established. In addition，the influence of different kinds of charging structure(coupling charge，decoupling charge with air and decoupling charge with water) on explosion energy transmission is discussed，so that different kinds of charging structure can be applied for different engineering blasting.

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PRELIMINARY DISCUSSION ON THEORETICAL MODEL OF ROCK DAMAGE MECHANICS

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2003, 22 (04): -646 doi:
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Based on the analysis of complete stress-strain curves for rock，and on the phenomenon that the reduction of elastic modulus and appearance of plastic strain happen simultaneously in the loading process，the basic hypothesis that elastic modulus and plastic strain are in direct proportion to damage is put forward. Based on the new conception of quasi-static damage process，the concepts of damage variable and release rate of damage strain energy are defined，and the relationship between them is analyzed. By the conservation of energy，the mathematical model of quasi-static damage process is brought forward. The dimensionless damage evolution equation and constitutive equation are set up and analyzed. The mathematical model set up in this paper includes only three constants，which are determined easily. The complete stress-strain curve is expressed with one damage evolution equation，whether for front or behind apex. The theoretical curve is in good agreement with the test result.

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STUDY OF THE LOADING PATTERN ON CIRCULAR
TUNNEL IN SOFT GROUND

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2003, 22 (04): -651 doi:
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The influencing factors of the loading on the circular tunnel in soft ground，such as tunnel embedment depth from the ground surface，construction techniques，and theoretical calculating approaches，are studied. The analysis of site-measured earth pressure on three tunnels in Shanghai soft ground shows that the earth pressure and magnitude distributions are not only varied with the method of tunnel construction (EPB shield or extruding shield method)，but also dependent on constructing and servicing phases. In constructing phase，for extruding shield method，the deformed tunnel lining is like a duck egg standing on end，while for EPB shield，it is like a lying duck egg. According to the Rankin dynamic and static earth pressure theory，the calculated earth pressure magnitudes are less than those measured in site，and the gap between them is fairly big. Based on the presented coefficients of lateral earth pressure and the assumption of cosine function of the earth pressure on circular tunnel in this paper，the calculated magnitudes have good agreement with the site-measured values for the studied three tunnels in Shanghai soft ground.

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REASONABLE MATCHING OF DIAMETERS AMONG
BOREHOLE，BOLT AND RESIN

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2003, 22 (04): -659 doi:
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[PDF 276 KB] (1176)

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Based on laboratory and in-situ tests，the reasonable matching relationship is presented among diameters of borehole，bolt and resin. The research result is important in guiding bolt support parameter design.

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STUDY ON ROCK DRILLING BY SWIRLING JET

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2003, 22 (04): -664 doi:
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[PDF 273 KB] (926)

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Based on the previous research on structural and flow characteristics of swirling jet，the testing study is made to analyse the factors affecting rock breaking efficiency of swirling jet，such as pump pressure，jet distance，rock permeability and intensity，consistency of additive，etc. Meanwhile the distinction of the effects of rock permeability on swirling jet and straight jet is studied. The results show that rock breaking efficiency by swirling jet apparently increases with the decrease of rock strength and the increase of rock permeability at the same standoff distance and pump pressure. The rock permeability plays important role in the rock breaking effect of jet. The effect of rock permeability on the swirling jet is greater than that on the straight jet. Meanwhile the results show that the depth，diameter and volume of the hole drilled by swirling jet apparently increase at the beginning and decrease afterwards with the increase of consistency of additive. The most excellent consistency of additive is 200～300 mmp in this experiment.

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EFFECTS OF FOUNDATION DEFORMATION ON WIND-INDUCED
BUFFETING RESPONSE AT CONSTRUCTION TWIN-CANTILEVER STRUCTURE OF CABLE-STAYED BRIDGE

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2003, 22 (04): -669 doi:
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[PDF 267 KB] (863)

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The effects of caisson foundation deformation on wind-induced buffeting response at twin-cantilever construction stage of cable-stayed bridge are studied in this paper. In consideration of foundation deformation，the analytical method of wind-induced buffeting response at twin-cantilever construction stage of cable-stayed bridge，whose caisson foundation of bridge tower is located in soil layer，is established. Taking the Haikou Century Bridge as an example，computational results show that the foundation deformation has notable influence on buffeting displacement response，but little effect on longitudinal buffeting bending moment at the bottom of the tower.

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ANALYSIS ON PILE-SOIL STRESS RATIO FOR COMPOSITE GROUND UNDER EMBANKMENT

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2003, 22 (04): -674 doi:
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[PDF 249 KB] (1316)

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The calculation method for the pile-soil stress ratio of composite ground under embankment and the calculation parameters are different from those of composite ground under rigid foundation due to the different settlements of pile and soil of composite ground，which results in vertical relative displacement in fill column and change in the stress state. An equation to solve the pile-soil stress ratio is established by mechanics analysis on the fill column above the composite ground under embankment. The observed results in an engineering project prove the availability of the equation. It is shown through the equation that the pile-soil stress ratio of composite ground under embankment is affected strongly by such factors as replacement ratio of composite ground，difference of settlement between pile and soil at the level of top of pile，height of fill，elastic modulus of fill.

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ENGINEERING APPLICATION STUDY OF SQUEEZED
BRANCH PILE WITH HIGH ANTIPULLING BEHAVIOR

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2003, 22 (04): -678 doi:
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[PDF 301 KB] (990)

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The antipulling behavior and the formula of antipulling capacity of squeezed branch pile are analysised in this paper. It is pointed out that with engineering consideration，the antipulling capacity is dependent on branch resistance. The presented study results are provided as theoretical basis for antipulling design of squeezed branch pile.

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TWO TYPICAL EXAMPLES OF DYKES WITH DEFECTS OR IN DANGER RESULTED FROM BED ROCK PERMEATION

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2003, 22 (04): -683 doi:
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This article presents two typical examples of engineering geological problems in dykes with defects or in danger resulted from permeation through the underlying bed rock：fault-typed permeation at dyke foundation in Shijiao Section of Beijiang River Dyke and the resulted osmotic deformation，the covering type of karst dyke foundation permeation in the auxiliary dyke of Huangbizhuang Reservoir and the resulted large-scale collapse of the dyke body. It has been found in artificial isotopic tracing，natural tracing，in environment isotopic and water chemical analysis，and in the determination of ground layer density，that there is a severe water-permeating fault of NE strike in the underlying bed rock of Shijiao Section of Beijiang River Dyke，which is directly related to the dangers during the flood seasons for years. It has been further determined by applying the plane thermal source principle that this fault is basically flat and straight in space and is dipping to NW. Bed rock karst is the objective geological foundation of the collapse of the auxiliary dyke of Huangbizhuang Reservoir，and improper construction method for anti-permeation consolidation is the first direct inducing cause to the collapse.