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2004, 23 (21): 0-0 doi:

[PDF] 137 KB (766)

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ENERGY DISSIPATION OF ROCK DEFORMATION AND FRACTURE

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2004, 23 (21): 3565-3565 doi:

[PDF] 306 KB (1917)

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As a kind of inhomogeneous and complex geological material，rocks are of distinctly nonlinear and anisotropic mechanical behavior. The deformation and fracture of rocks are an evolution process with exchange of energy and mass between rocks and outer exotic environment. The variation rule of the damage variable and the coupled variable，damage energy dissipation rate，can be described on macro aspect by the damage evolution equation. Furthermore，the intrinsic mechanism of energy dissipation during the deformation and fracture of rocks can be disclosed by the research of meso damage mechanics. Some progress is reviewed related to energy dissipation in the field of rock mechanics，and a macro-meso-micro system based on damage evolution and energy dissipation is suggested，which contributes to solve more engineering problems exactly.

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TESTING STUDY ON MECHANICAL EFFECT FOR LIMESTONE
UNDER CHEMICAL EROSION

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2004, 23 (21): 3571-3571 doi:

[PDF] 307 KB (1294)

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Based on the results of triaxial compressive test，the effect of different chemical erosion on complete stress-strain process for limestone is analyzed. The influence laws of different chemical solution on deformation and strength erosion of limestone are obtained．

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ELASTO-PLASTIC DAMAGE MODEL FOR GEOMATERIALS
AND STRAIN LOCALIZAION ANALYSES

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2004, 23 (21): 3577-3577 doi:

[PDF] 452 KB (1212)

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Elasto-plastic models can not explain the micro mechanism of shear band formation caused by damage evolution in ductile material due to the neglecting of the interaction between damage and plastic flow. An elasto-plastic damage model for geo-materials based on micromechanics is proposed and the micro mechanism of shear band formation in homogeneous geo-material is studied. A macroscopic yield criterion for porous geo-materials with matrices of Drucker-Prager yield criterion is given，and a plastic strain-controlled void nucleation model as well as a tensile volumetric stress-controlled nucleation model are proposed for the compressive and tensile stresses，respectively. Moreover，the constitutive relationship of the elasto-plastic damage model with plastic normality flow rule is deduced. This elasto-plastic damage model for geo-materials is embeded into the commercial FEM software MARC as a user’s subroutine. A tensile plane strain specimen with initial shape imperfection on its upper bound which was first analyzed by Tvergaard is investigated through the elasto-plastic damage model and Mises elasto-plastic model，respectively. It is shown that the shear band development is only found in Gurson elasto-plastic damage model. Shear band formation due to void nucleation and growth in a plane stress specimen of homogeneous geo-material with one defect element subjected to uniaxial compression is analyzed by the model.

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CT REAL-TIME TESTING STUDY ON EFFECT OF WATER ON CRACK GROWTH IN FRACTURED ROCK MASS

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2004, 23 (21): 3584-3584 doi:

[PDF] 257 KB (1612)

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By using the accessory loading equipment corresponding to the CT machine and simulation material，the CT real-time testing of specimens with single crack with and without water in it is conducted to observe the complete process of crack growth. The failure form of the crack including its generation，evolution，development and final failure under complex stress and various underground water conditions is investigated. Different models of crack propagation in geotechnical engineering under the conditions with and without water and hydraulic pressure are constructed，respectively. It is shown that there exist different failure forms of rock mass under three conditions from the CT scanning，but the CT images with compressed microcrack，damage evolution，microcrack growth and macrocrack generation are clear. It is concluded that the influence of underground water conditions on rock engineering must be taken into consideration. At the same time，some scientific hypotheses of the damage evolution equations and stress-strain relationship as well as the failure mechanism of rock mass are also proposed.

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3D NETWORK SIMULATION TECHNIQUE OF JOINTS IN ROCK MASS AND PERMEABILITY TENSOR ANALYSIS

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2004, 23 (21): 3591-3591 doi:

[PDF] 322 KB (1234)

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On the basis of field geology survey，the probability distribution function of joint aperture is fitted and the availability of the fitting is verified. So the discs with thickness can be generated to simulate the joint. The permeability tensor of rock mass is proportional to the third power of joint aperture. It is more reasonable to analyse the seepage of rock mass combining the simulated 3D network with joint aperture by the method in the paper. The calculation of permeability tensor comprehensively considers the effect of joint orientation，aperture，scale and distribution.

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BASED ON GEOMETRY MEASURING METHOD

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2004, 23 (21): 3595-3595 doi:

[PDF] 251 KB (1071)

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The traditional and modern measurement methods of fractures are used to measure the fractures of rock mass in the grouting galleries of the left bank of a dam site area. Based on the measured results of fractures，the calculation method of permeability tensor is proposed and the relevant software using Visual Basic Language is developed. The merits of the software are easy to use and free of the trivial calculation due to visualization design. The software is used to calculate the permeability of fractures in the grouting galleries，and the results are validated. It is shown that the software can be used as a supplement for back analysis of water pressure experiment and can be used to provide scientific basis for the zoning of permeability of fractured rock mass and the optimization of curtain seepage prevention.

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ANALYSIS ON MESO-STRUCTURE EVOLUTION OF BRITTLE MATERIALS BASED ON ESTIMATION OF FRACTAL
DEMENSIONS OF SEM IMAGES

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2004, 23 (21): 3600-3600 doi:

[PDF] 407 KB (1299)

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The evolution characteristics of materials play an important role in the research of material damages. Meso-structure images of a cement specimen under various stress levels are investigated by using the scanning electronic microscope (SEM). The fractal dimensions of these meso-structure images are estimated by image analysis and fractal theory. On the basis of the fractal dimension of meso-structure，the characteristics of the evolution of meso-structure are quantitatively analyzed. It is shown that the value of fractal dimensions，derived by the above-mentioned method，increases with the evolution of the damage，and near the end of loading，the fractal dimensions increase prominently，which means that the damage in the cement specimen becomes more chaotic when the strain approaches its limiting value. It has suggested that the fractal dimensions defined in the paper can be used as indicators for damage in cement materials to depict the evolution of damage or micro cracks.

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2004, 23 (21): 3604-3604 doi:

[PDF] 723 KB (857)

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FRACTAL AND STATISTICAL ANALYSIS OF STRENGTH OF JOINTED ROCKS

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2004, 23 (21): 3608-3608 doi:

[PDF] 333 KB (1167)

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Large number of joints exist in rocks. Their sizes and directions are distributed in a random way. Studies have shown that the distribution of joints can be quantitatively described by using the fractal dimensions. Based on two rupture modes，fracture propagation and shearing slide，the statistical strength of jointed rocks is derived with the help of the statistical fracture mechanics. The result shows that the strength of jointed rocks strongly depends on the fractal dimension of rock joints. The small increase of fractal dimension will lead to rapid decrease of rock strength.

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TESTING STUDIES ON RESPONSE BEHAVIOUR
OF ROCK SALT TO IMPACTING

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2004, 23 (21): 3613-3613 doi:

[PDF] 511 KB (1044)

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The response behaviour of rock salt under combined compression and shear impact loading are investigated by utilizing the S-Wave Tracing techniques，and correlative characteristics of dynamic damage are obtained by tracing changes of shear behavior during dynamic damage of rock salt. Impacting experiments with different impact velocities are conducted under combined compression and shear impact loading. Testing results show that (1) rock salt is in fracture phase when impacting velocity is more than 200 m/s，and (2) rock salt is in dynamic damage phase when impacting velocity is at 70～200 m/s. An important experimental phenomena is discovered for the first time in the impacting dynamic experiments，that is to say，there is another unloading shear wave before the unloading compress wave besides routine four impact waves in the process of compress-shear impact of rock salt，which is greatly different from other brittle materials.

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ACOUSTIC EMISSION EXPERIMENTAL RESEARCH ON
LARGE-SCALED ROCK FAILURE UNDER CYCLING LOAD
——FRACTURE PRECURSOR OF ROCK

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2004, 23 (21): 3621-3621 doi:

[PDF] 372 KB (1391)

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The microfractures in a brittle material like rock may appear or grow while loading. Microfracturing process in a material results in energy dissipation and acoustic emission(AE). Acoustic emission is a good tool to detect the damage in brittle materials. Because it can monitor the microfractures in the body continuously and in-real-time and is better than other methods. Large-scaled gneiss failure experiments under triaxial loading are conducted. The size of the specimen reaches 1.05 m. In order to simulate the effect of tide-generating force of the sun and the moon，a cycle stress is loaded superposing on a basic axial load level. Lots of acoustic emission during the entire loading are recorded. The recording is able to indicate the occurrence time，location and magnitude of every damage (micro-crack) in the specimen. Acoustic emission record is used to study the two macroscopic failure precursors of rock，accelerating energy release (AER) and load/unload response ratio (LURR)，which can be served as the experimental foundation of earthquake prediction. At the same time the Felicity effect is identified in the experiment.

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FINITE ELEMENT FORMULATION OF GENERALIZED INVERSE MATRIX FORCE METHOD FOR MATERIAL NONLINEARITY PROBLEMS

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2004, 23 (21): 3629-3629 doi:

[PDF] 458 KB (988)

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The finite element formulation of generalized inverse matrix force method，or so-called large increment method (LIM) for material nonlinearity problems is proposed. LIM is a new iteration method，which is based on theories of the force method and generalized inverse matrix (GIM)，and is of unique characteristics and advantages especially for material nonlinearity problems. Unlike the conventional incremental method based on the displacement method，which can not avoid time consumption and error accumulation，the proposed new method can work with very large increment up to several loading cycles as based on the force method. Unlike the classical force method，LIM does not need to find some basic structure any more. Consequently，this method sheds a new light to the force method in the computational mechanics. In addition，LIM is of intrinsic parallel-calculating characteristics，which are different from the traditional sub-structural algorithm based on displacement method. The algorithm can be divided into the global stage and the local stage. The finite element formulation with consideration of material nonlinearity is given. It includes the expression of consistent elastoplastic flexibility and stiffness matrix. An example of plane stress problem is also given to show the generality of this new method.

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LARGE-SCALE HIGH PERFORMANCE PARALLEL FINITE
ELEMENT SYSTEM BASED ON DOMAIN DECOMPOSITIOIN
METHOD IN GEOMECHANICS

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2004, 23 (21): 3636-3636 doi:

[PDF] 444 KB (1301)

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The finite element (FE) simulation often finds itself difficult to meet the time and accuracy requirements due to the large scales of projects and complexity of rock properties. To fully utilize the potential of FEM，large-scale parallel FEM are investigated on Windows. PC cluster on Windows operating system is built up. The‘Divide and Conquer’strategies are used to parallel the FEM，and locality of storage is implemented. The equations are solved using the parallel preconditioned conjugate gradient method by domain decomposition method. Integrated with the above-mentioned methods，a parallel FE system，ParallelGeoFEM is developed in C++. A 3D FE underground powerhouses model is simulated，and good speedup ratio is obtained. The results show that the parallel FEM based on domain decomposition method can be used to achieve accurate and good geotechnical simulation within a reasonable short time.

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SELECTION STUDY OF COMPUTATIONAL PARAMETERS FOR
DEM IN GEOMECHANICS

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2004, 23 (21): 3642-3642 doi:

[PDF] 438 KB (1248)

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A brief analysis is made on the selection of geometric and physical parameters for the computation of geomechanics. By comparison of several different DEM contact relationships，the physical meaning of joint stiffness in different computational models is discussed. In rigid block model，the joint stiffness is an equivalent stiffness reflecting the stiffness of rock block and joint. As for the deformable block model，the spring stiffness between blocks should be large enough to reflect the real characteristics of rock mass. In general，oversized contact stiffness may influence the computational reliability，and a simple treatment to get rid of the influence is proposed. The damping expression of structural vibration for rock mass is given by dimensional analysis，and the damping ratio can be obtained through vibration test. The characteristic time obtained from dimensional analysis offers a reference value for computational time step. In the end，the criteria of computing control，slide and failure in DEM are introduced.

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STOCHASTIC MODEL AND NUMERICAL SIMULATION FOR DISCONTINUOUS JOINTED ROCK MASS USING 3D DEM

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2004, 23 (21): 3652-3652 doi:

[PDF] 336 KB (1042)

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A stochastic model for discontinuous jointed rock mass is presented. In the model，according to the statistical distribution function of structural surface，the spatial stochastic distribution of structural surface is simulated on the assumption that the shape of structural surface is square. The implementation approach and algorithmic reliability of the stochastic model are revealed. Through uniaxial compression simulation，the relation between strength of jointed rock mass and its influence factors such as joint obliquity and connection rate is studied under one set of diagonal joints. The computational results are compared with the theoretical value which is deduced through limit equilibrium condition to validate the stochastic joint model，and the similarities and differences between them are analyzed. Also the relationship between equivalent elastic modulus of discontinuous rock mass and connection rate of joint is studied with their influencing relation presented.

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UDEC SIMULATION ON DYNAMIC RESPONSE OF ROCK
SLOPE OF HUANGMAILING PHOSPHORITE MINE UNDER EXPLOSION

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2004, 23 (21): 3659-3659 doi:

[PDF] 251 KB (1295)

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The dynamic response of rock slope of Huangmailing phosphorite mine under explosion is simulated by UDEC and compared with that of site monitoring. It is shown that the simulated vertical and horizontal velocity history of the slope toe agrees well with the monitoring results. The deviation of the calculated peak particle velocity of the slope toe from that of site monitoring is less than 20%. For this case，UDEC can be used to effectively simulate the dynamic response of jointed rock slope.

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NUMERICAL ANALYSIS ON RUPTURE OF SUBFLOOR OF COAL
MINE TUNNEL SUBJECTED TO BLASTING LOADS

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2004, 23 (21): 3664-3664 doi:

[PDF] 777 KB (1259)

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By taking an accident of tunnel subfloor water penetration of a coal mine in southwest China induced by blasting as the background，the explosive stress wave and its transfer in rock stratum as well as the rupture process of tunnel subfloor are simulated and analyzed by using the ANSYS/LS-DYNA software. The explosive charge and the effects of rock stratum interface are considered in the numerical model. The critical explosive charge resulting in the concrete subfloor fracture is obtained. The influence of interface of dried and saturated rock stratum on subfloor fracture is studied.

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Zhang Leiming，Liu Xila

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2004, 23 (21): 3669-3669 doi:

[PDF] 460 KB (920)

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The equations of motion are established referring to the current-unstressed configuration，by which the coupling between axial forces and bending moments is naturally considered without introducing geometric stiffness matrix. The iteration formulation is then given and its convergence is also discussed. The dynamic analysis of an 8-story frame is conducted. It is shown that，in comparison with the calculated results from the conventional method，the peak values of dynamic response are reasonably increasing，but the frequency responses remain nearly unchanged.

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LANDSLIDE MONITORING AND INTELLIGENT ANALYSIS ON DEFORMATION PREDICTION BASED ON THREE DIMENSIONAL GEOGRAPHIC INFORMATION

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2004, 23 (21): 3673-3673 doi:

[PDF] 347 KB (1653)

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Based on the integrating technology of landslide monitoring and three-dimensional geographic information，a monitoring information system of three-dimensional landslide is proposed. Subsequently，the synthetic expression of in-situ monitoring information and three-dimensional geographic information is implemented in the system，which provides an information platform for the synthetic analysis of monitoring scheme and its visualization. Aiming at the nonlinear evolutive problem of landslide displacement，the basic ideas of time series are employed，and the genetic algorithm is used in determining the structure and parameters of the time series model which are then used in the construction of the predicting model for landslide deformation. The Bachimen landslide of Funing highway，Fujian，China，is taken as an example to show the basic structure，functions and algorithm of the system of three-dimensional monitoring information. In addition，the landslide displacement based on the in-situ monitoring data is predicted.

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MECHANISM OF PROGRESSIVE FAILURE OF A KIND OF FAULTED ROCK SLOPE DUE TO SLIP-WEAKENING

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2004, 23 (21): 3679-3679 doi:

[PDF] 284 KB (873)

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Slip-weakening is one of the characteristics of faulted rock material under a certain loading condition. Non-uniform rock structure may exist in the vicinity of the slip surface in a rock slope. Some portions of the slip surface may be mutually penetrated but the others may not. For the latter case，the cracks or the fault surfaces will undergo shear deformation before a successive surface forms under certain loadings. As the slipped portion advances，slip-weakening occurs over a distance behind the crack tip. In the weakening zone，the shear strength will decrease from its peak value to residual friction level. The stress will redistribute along the crack surface. Therefore the changed local stress concentration will cause the crack to extend and the ratio of penetration of the slip surface will increase. From the large-scale view of the whole slip surface，the shear strength will decrease due to the damage of the interior rock structure，and the faulted rock behaves as a softening material. Such a kind of mechanism happens in many practical landslides subjected to strong earthquakes. It should be noted that this mechanism is different from that of the breakage of structural clay，in which the geological material is regarded as a medium containing structural lumps and structural bands. The strain-softening property exhibited in the structural clay is the result of structure damage (i.e. the disintegration of the soil structure). The softening behavior of faulted rock should be regarded as a comprehensive result of the whole complicated process including slip-weakening，stress redistribution，crack tip extension and the penetration of slip surfaces. This process is accompanied by progressive failure and abrupt structural damage. The size of slip-weakening zone is related to the undergoing strain. Therefore，once a landslide is initiated (local or integrated)，the effect of slip-weakening will exist in a certain length behind the crack tips until the formation of the whole slip surface even without dynamic loading.

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DISCUSSIONS ON THE GENERALIZED SLICING METHOD
FOR STABILITY ANALYSIS OF SLOPES

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2004, 23 (21): 3684-3684 doi:

[PDF] 285 KB (912)

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Limit equilibrium slicing methods have been widely used for assessing the stability of natural and man-made slopes. Many methods have been developed so far. They involve various assumptions with respect to the inter-slice forces which lead to different results. In order to get rid of these inconsistencies，attempts is made to incorporate the commonly used slicing methods into a generalized frame work. However，what is the most reasonable result is still unknown. Therefore，a generalized frame work is proposed to find a reasonable bound of solutions of slicing methods for both the two-dimensional and three-dimensional cases. By analyzing the influences of various conditions on the results of stability analysis，the existence and uniqueness of the safety factor are discussed. Analytic formulas of the safety coefficient under different conditions are established. In addition，variation formulas of the safety coefficient are obtained for determining a proper bound of the safety factor.

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RESEARCH ON SATURATED AND UNSATURATED FLOW
MECHANISM OF CLAYSTONE

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2004, 23 (21): 3689-3689 doi:

[PDF] 360 KB (1372)

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Coupled unsaturated flow in claystone has high effect on strength and stability of underground engineering. Based on experimental results of unsaturated flow in claystone，mechanical and unsaturated flow coupled constitutive model is applied to simulate the shrinkage and swelling phenomena in claystone tunnel during excavation，concrete support and ventilation processes. The whole flow process in claystone from state of saturated to desaturated state and then to resaturated state is obtained from the numerical results. The achievements are quite useful to explain the argillization and collapse mechanism in practice，and have great theoretical and practical significance.

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STUDY ON INTEGRATION OF 3D STRATA INFORMATION
SYSTEM AND FEM

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2004, 23 (21): 3695-3695 doi:

[PDF] 411 KB (1054)

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Three-dimensional strata information system(3DSIS) is a system for storing，managing，checking，manipulating and displaying data which are spatially referenced to the underground strata. But the grids for visualization in 3DSIS are triangular prisms and can’t be directly used in finite element method. Based on the principle of mesh generation in FEM，the reasons are given that the visualization grids in 3DSIS can’t be used in FEM. A local-whole(L-W) model which is suited to 3D visualization and FEM is put forward. Using the L-W model，the grids are easily changed into the meshes of FEM. The key points that control the stratum shape are obtained by the topological analysis，and then lines and areas are defined，and solid model features are generated from the bottom up，and then new grids are regenerated. An integration system of 3DSIS and FEM is developed by the method of mixed-language programming using FORTRAN and Visual C++. And at last，the application of the integration model is given.

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RISK ANALYSIS OF ENCOUNTERING ROCKFALLS ON A HIGHWAY——
A CASE STUDY

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2004, 23 (21): 3700-3700 doi:

[PDF] 854 KB (1120)

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The south line of the Chengdu-Lhasa highway，which is of great importance for national defence，is one of the two main transportation corridors connecting Tibet with the inland of China. As the most dangerous traffic route entering Tibet，a 430 km long highway section (from Paksho to Nyingtri) with typical geological hazard is investigated for frequent rockfall events. Firstly，based on the EGMS methodology，rockfall frequency is estimated by combining all the possible knowledge of site investigation，experience and theoretical analysis for 19 rockfall zones along the highway section，and annually averaged probability of rockfall events under three situations of immobile vehicles，mobile vehicles and foot passengers，is calculated by using Bernoulli formula. Secondly，probability of deaths resulting from rockfalls in the 19 zones is obtained from the encountering probability and vulnerability analysis for highway users. The risk assessment indicates that (1) fatal risk of passing rockfall zones Rm4，Rm5，Rs1，Rs4，Rs5，Rs10 and Rm7，is higher than that in other rockfall zones；(2) there are little differences in traffic conditions and human activities along the highway section，hence the hazard assessment for the rockfall zones has a result，to some degree，consistent with risk assessment；and (3) fatal risk of rockfalls along the highway section is prominently higher than that of landslide hazards in some developed countries or regions.

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THEORETICAL ANALYSIS ON FULL THERMO-HYDRO-MECHANICAL COUPLING FOR ROCKS UNDER FREEZING TEMPERATURE

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2004, 23 (21): 3709-3709 doi:

[PDF] 275 KB (934)

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The mechanical properties of rock may change dramatically due to porous water，discontinuity and sub-zero temperature. The traditional principles of thermodynamics, however, can not solve this problem or explain the phenomena. Based on the principles of irreversible thermodynamics and the mechanics of continuous medium, the continuity equation, equilibrium equation and energy conservation equation can be coupled via some simplified assumptions. Moreover，the relationship between rock and ice in a frozen rockmass is studied and a coupled coefficient of expansion is proposed. It gives a new theoretical basis for studying temperature, seepage and stress distribution in rock mass in cold regions.

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ANALYSIS ON HYDRODYNAMIC FIELD INFLUENCED BY COMBINATION OF RAINFALL AND RESERVOIR LEVEL FLUCTUATION

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2004, 23 (21): 3714-3714 doi:

[PDF] 392 KB (1416)

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Influenced by the combination of rainfall and reservoir level fluctuation，the determination of groundwater level in landslides is of great importance in assessing the stability of the landslides along reservoir. According to precipitation data from year 1957 to 1988 in Fengjie County in the Three Gorges reservoir area，the probability analysis is conducted by using the extreme distribution and the related rainfall model is developed. Considering the various adjustment of reservoir level in the Three Gorges，its adjustment model is given. In the two models，the rainfall and the change of reservoir level are considered by day in terms of practical situation. A method is then proposed accordingly to study the hydrodynamic field of unsteady fluid flow influenced by this combination. The hydrodynamic field of Baiyi′an landslide is analyzed by this method. Groundwater is calculated in various conditions，and the worst case and its probability are given by comparison.

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HYDRODYNAMIC MONITORING OF A PREEXISTING LANDSLIDE DURING RESERVOIR FILLING——A CASE HISTORY OF XIETAN LANDSLIDE，THE THREE GORGES RESERVOIR

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2004, 23 (21): 3721-3721 doi:

[PDF] 536 KB (1356)

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Reservoir slope instability is a geological hazard induced by construction of hydroelectric project and is generally believed to be caused mainly by the unfavorable change of hydrodynamic condition in the slope due to reservoir filling and/or operation. Many cases of reservoir slope instability can be found both in China and abroad，the evolution of the hydrodynamic conditions，however，is mainly obtained by seepage analysis，while the systematic and complete field instrumentation data can rarely be found. Taking the opportunity of filling the Three Gorges Reservoir，an automatic hydrologic monitoring system is implemented to monitor the hydrodynamic evolution of a preexisting landslide，Xietan landslide in Zigui County，Hubei Province，China. The system includes the monitoring of reservoir water level，water level in boreholes，seepage pressure and precipitation，etc. The comprehensive analysis of the monitored data shows that the rising speed of water level (or seepage pressure) on the reservoir bank lags behind that of the reservoir filling and the lagging time is closely related to the permeability of materials of the bank. The weaker the permeability of the slip band，sliding-disturbed zone and bed rock are，the longer their lagging time is. If the permeability of the main body is quite good，then only a short lagging time can be observed. Water level data from observation wells are misleading and should be analyzed with the well structure，and standpipe should be used whenever possible. Rainfall-induced water level rising in the main body and its lagging time are greatly influenced by rainfall intensity. Heavy rainfall takes less time to infiltrate into the slope and induces higher water level rising. Therefore，for the analysis of rainfall influence，a basic time unit should be determined according to the rain type. Basic time unit of hour is feasible for Xietan landslide.

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DESIGN AND DEVELOPMENT OF A NEW TYPE OF TRIAXIAL
SYSTEM FOR ROADWAY MODEL TEST

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2004, 23 (21): 3727-3727 doi:

[PDF] 329 KB (1235)

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A new type of triaxial system developed for roadway model test is reported. The main advantages of this new servo-controlled test system are the high stiffness and small size in frame. During tests，the model can be flexibly loaded by six flat jack in three mutually perpendicular directions with arbitrary loading ratios. The system is capable of testing specimens with 1 m in width，1 m in height and 0.2 m in thickness. The servo-controlled maximum pressure is 10 MPa. So the system is capable of performing advanced tests such as floor heave of roadways in deep mining. In addition，other relevant experimental techniques on roadway stability model tests and similar material simulation are also introduced.

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STUDY ON STABILITY OF DEEP ROCK ROADWAYS IN COAL MINES
AND THEIR SUPPORT MEASURES

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2004, 23 (21): 3732-3732 doi:

[PDF] 280 KB (1298)

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Based on model test，in-situ investigation，and theoretical analyses，the influencing factors on stability of rock mass surrounding coal-mine roadways 800～1000 m deep are studied. The mechanism for effects of high crustal stress，high-level permeable pressure，and high temperature gradient on the stability of deep roadways is concluded，and corresponding support method and technology are carried out which include a kind of bolts with initial support force of 30～50 kN and peak support force higher than 300 kN and their arrangement in surrounding rock，bottom bolts and their construction tools，fiber-optic monitoring technology for bolt stress for long term，and grouting technology for sealing fractures，cutting seepage off and reinforcing rock mass.

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NEW METHOD OF PREDICTING RAINFALL-INDUCED LANDSLIDES

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2004, 23 (21): 3738-3738 doi:

[PDF] 188 KB (1237)

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Historical data of landslides and rainfall of some counties and cities in the Three Gorges area are investigated in detail，and the relationship between rainfall and rainfall-induced landslides is analyzed from three different points of view，rainfall，rainstorm and rainfall duration. The conception of rainfall-factor is suggested thereafter. At the same time，a new method of predicting rainfall-induced landslides is proposed to depict the probability of rainfall-induced landslides quantitatively. Every rainfall-sub-factor is graded according to some criteria，and then the relationship between rainfall-factor and rainfall-induced landslides is studied. It is proved that this new method of landslide prediction can predict the occurrence time of landslides with higher precision through applying it to Wanxian，a city in the Three Gorges area. This method of landslides prediction would lay a solid foundation for predicting rainfall-induced landslide according to historical data of rainfall and landslides.