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2003, 22 (05): -0 doi:
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RESEARCH ON ANALYSIS METHOD AND CRITERION OF
ROCKMASS STABILITY

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2003, 22 (05): -691 doi:
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[PDF 388 KB] (1536)

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On the basis of evaluation on current analysis methods of anti-slide stability in rockmass engineering，their deficiency are pointed out. With the application of the friction theory and the vector geometry，the formula of anti-slide stability safety coefficient is presented based on the non-linear FEM analysis. According to the mechanics principle of engineering stability，the disturbing energy method of rockmass stability criterion is presented. In response to the stability problem of rockmass without conspicuous slide faces，based on quantitative disturbing energy criterion and static criterion，the quantitative criterion standards of the latent slide face and the most dangerous slide direction and the minimum stability safety coefficient are proposed and formulated. The stability criterion system is perfected on rockmass engineering. The mechanics foundations are laid for quantitative stability criterion on surrounding rock without conspicuous slide faces. The disturbing energy method may be used to determine the latent slide body and the possible slide direction，and the composite criterion of rock-mass stability is worked out by combining the static method. On the analysis of rockmass stability by the static method，the difficult problem of determining the slide face and the slide direction is solved. Moreover，the application results of the disturbing energy method and the static method may be used to check up each other，and the criterion system of rockmass stability is formed. The stability computations of surrounding rock in underground chambers and high dam abutment with height of 305 m are given for two engineering projects. According to the disturbing energy value and its isograph，the latent slide faces are determined. Estimating rockmass stability by the disturbing energy method and the static method，the numerical results indicate the rationality and the feasibility of the presented method.

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STUDIES OF INFLUENCE DEGREE OF MECHANICAL PARAMETERS ON DISPLACEMENTS IN ELASTO-PLASTIC MODEL FOR ROCK MASS

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2003, 22 (05): -697 doi:
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[PDF 195 KB] (1030)

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Back analysis of displacements for the mechanical parameters of an elasto-plastic model for rock mass can be included to an optimization problem. However, before solving the problem，the mechanical parameters influencing the objective function of the problem have to be identified. That is，the mechanical parameters，which can be determined by back-analyzing the displacements in the elasto-plastic model for rock mass，have to be recognized. The Fast Lagrangian Analysis of Continua (FLAC) is used to conduct numerical simulation on displacements around an underground stope. The test design approach on orthogonal table is used to plan the simulation，and the mathematical statistics approach is used to analyze the influence degree of mechanical parameters on displacements in the elasto-plastic model. Approach is established to assess the influence degree of these parameters and identify the parameters which can be determined by back-analyzing the displacements in the elasto-plastic model.

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ANALYSIS ON DAMAGE MECHANICS MODEL OF ROCK

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2003, 22 (05): -702 doi:
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According to the phenomena that elastic modulus is reduced and plastic strain increased while rock is compressed，the math model of rock damage is set up. The parameters of peak on curve of stress-strain are analyzed，so that invariables of rock can be calculated by test result. Comparing two different models，it is proved that the relationship between stress and strain is completely the same，while the definition of damage variable is discretional. It means that different definition of damage variable may be equivalent. The conclusion is that whatever the essential of damage is，there is a damage variable to correspond a stationary energy release rate of damage. The damage rate and energy release rate of damage are analyzed for the compressing process with stationary strain rate and the character of acoustic emission is explained as rock specimens are compressed.

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RESEARCH ON PARALLEL EVOLUTIONARY NEURAL NETWORK FEM
FOR STABILITY ANALYSIS AND OPTIMIZATION OF LARGE CAVERN GROUP——PART Ⅰ: THEORY MODEL

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2003, 22 (05): -706 doi:
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With ever enlarging scale of the underground cavern group，recognition of relevant parameters and scheme optimization would be highly nonlinear and of multi-extreme values in the solution space. It is much in need of finding an available method of global optimization and parallel computation. So a new parallel evolutionary neural network FEM is put forward. Through the sample construction by FEM calculating，the mapping relationship among the calculating schemes，the maximum displacement and the volume of damage zone is set up by parallel evolutionary neural network，and a group of initial feasible schemes are given by genetic algorithms(GAs). Evaluated by the maximum displacement of key spots and volume of damage zone，a group of new schemes are generated by operation of GAs. The operation is done until the reasonable scheme is found. The parallel computation is carried out on independently developed parallel environment(RsmVPC) based on WINDOWS platform. The methodology makes it possible to solve the large scale optimization problems parallelly on PC machine groups，and to improve the computing speed，scale and precision to a large extent with the proposed method.

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GENERATION OF COVER SYSTEM FOR NUMERICAL MANIFOLD IN TRAVEL THEORY OF THE ORIENTED GRAPH

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2003, 22 (05): -711 doi:
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[PDF 418 KB] (1239)

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A generation algorithm of cover system for numerical manifold method(NMM) is introduced. This algorithm is based on the travel theory of the oriented graph and the formation of the block system is incised by the joints and fractures. By this algorithm combined with the adaptive generation technology for finite element method(FEM) mesh，the mathematics mesh is built，and then in the travel theory of the oriented graph，a final cover system for NMM can be efficiently formed. This method also provides a way to obtain the available element library for the FEM in the NMM based on existing FEM elements.

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DELAUNAY ALGORITHM AND RELATED PROCEDURE TO GENERATE THE TETRAHEDRON MESH FOR AN OBJECT WITH ARBITRARY BOUNDARY

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2003, 22 (05): -717 doi:
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[PDF 534 KB] (2526)

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Based on Delaunay algorithm，an algorithm is presented to fulfill the generation of tetrahedron mesh. The algorithm is effective for three-dimensional object of arbitrary shape，and it uses some data structures，such as array，chain and structure，to manage the nodes and the elements. Base grid is used to accelerate the generation of tetrahedron mesh. When a new node is added to the existing mesh，the bound face of the new node’s Delaunay cavum must be checked，to avoid the overlapping of tetrahedron elements. A method is brought forward to judge whether a node is inside an arbitrary closed area or not，and it can be used to generate the Delaunay mesh for concave object. Examples show that the algorithm is effective to approach to arbitrary coincide.

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PROBABILITY MODEL FOR ESTIMATING CONNECTIVITY
RATE OF DISCONTINUITIES AND ITS ENGINEERING APPLICATION

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2003, 22 (05): -723 doi:
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In spite of the extreme significance of connectivity rate of discontinuities for rocks，the method for estimating connectivity rate had not been put forward until H-H probability model was introduced in 1998，based on the intersectant probability between discontinuities and window measured. However，H-H probability model requires that discontinuities should be distributed homogeneously and the distance between discontinuities should be shorter than the length limited by size effect. In order to overcome these disadvantages，an equivalent model for distribution of discontinuities is built. On the basis of this equivalent model，the generalized H-H probability model of connectivity rate estimation is deduced. In order to test its correctness，it is used to calculate connectivity rate of discontinuities for sideslip surface in a large hydropower project in southwest China. It is showed that the connectivity rate estimated by this method agrees wel with the measured one.

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RESEARCH ON CREEP-CONSOLIDATION CHARACTERISTICS AND CALCULATING MODEL OF SOFT SOIL

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2003, 22 (05): -728 doi:
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[PDF 406 KB] (2052)

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Based on the research trends of soil rheology and the stringent demand of practical engineering，the characteristics of creep-consolidation in soft soil，computational model，homologous numerical method and its application in engineering are systematically studied. The coupling of stress-strain model for soil and rheology model as well as consolidation model is researched. The practical model of nonlinear elasto-viscous consolidation is established. The study results show that the total displacement of soft soil，at given time，can be divided in instantaneous part and creep part. The instantaneous strain also presents obvious nonlinear property，and the time-dependent behavior of soil deformation is depended on its consolidation and viscosity. When stress level is lower，the displacement results mostly from consolidation. Otherwise the displacement primarily originates from shear creep. The creep deformation of soil is related to pore-pressure dissipation. Under uniform conditions，the worse the permeability is，the larger the creep deformation is. For soft soil strata，the secondary consolidation occurs during the primary consolidation，and the influence of creep on stress and strain is decided by drainage condition of soft foundation. The stress level will rise with time when drainage condition is bad. The possible destroy may be missed，if the characteristics of creep are not be taken into account of calculation. So，for the security of an engineering，the creep considered not only corrects the calculation results，but also is an afresh evaluation. Through the calculation of a representative example，the rationality of creep-consolidation model and the validity of conclusions have been tested and verified.

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NUMERICAL SIMULATION ANALYSIS ON INFLUENCE OF TUNNEL EXCAVATION TYPES ON PILE FOUNDATION OF BUILDING

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2003, 22 (05): -735 doi:
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[PDF 628 KB] (1314)

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With a newly developed numerical code，Rock Failure Process Analysis (RFPA2D)，as well as numerical code FLAC2D，some numerical simulations of deformation and mechanical behaviors are made for a two-dimensional tunneling in the No.2 line tunnel of Guangzhou highway. By using the RFPA2D code，the model materials are considered as brittle and heterogeneous. The modified models of Mohr-Coulomb and tension cut-off are taken as the element failure criterion. Pile-base deformation and ground movement are inevitably caused by tunnelling construction in soil and rock ground. In urban areas，the potential effects on building are of great importance in the construction of tunnels by means of different excavating types. It is shown that the RFPA2D code is very promising to be used as a tool to study the ground movement and its failure mechanism.

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TESTING STUDY ON PORE RATIO AND PERMEABILITY
OF SANDSTONE UNDER DIFFERENT CONFINING PRESSURES

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2003, 22 (05): -742 doi:
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[PDF 337 KB] (1422)

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By using the triaxial rock mechanics experimental system，testing study is made to analyse the change rule of permeability during the whole stress-strain process and the pore ratio and permeability of sandstone under different confining pressures，and the qualitative and quantitative relationship is established among stress-strain and pore ratio permeability of sandstone. It is shown that during the whole stress-strain process，the permeability reduces slightly with the increase of stress in the elastic stage，after coming the elastic and plastic stage，along with expanding and breakthrough of the induced fracture，the permeability of the rock increases slowly at first and then sharply reaches the maximum value before or after peak point，and at residual flowage stage the existent fracture is pressed closely，and the permeability begins decreasing. The pore ratio and permeability of the sandstone are closely related to the effective confining pressure. The pore ratio and permeability decrease along with the accretion of confining pressure，and conform to the change rule of logarithm function. The sandstone of different diagenesis has different speed and degree in decreasing of pore ratio and permeability. It is shown that under confining pressure the pore ratio and permeability of the sandstone with weaker diagenesis are evidently higher than those of sandstone with stronger diagenesis at decreasing speed and degree. The results obtained from the testing study can be applied into the project of petroleum and gas exploitation，where the variation of in-situ stresses affect the pore ratio and permeability of strata evidently.

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INSTABILITY CRITERION OF SHEAR FAILURE FOR ROCK SPECIMEN BASED ON GRADIENT-DEPENDENT PLASTICITY

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2003, 22 (05): -747 doi:
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[PDF 237 KB] (1441)

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The instability criterion due to shear localization in rock specimen system composed of shear band and elastic rock outside the band is studied. A few important phenomena observed in test are considered as basic assumption for obtaining closed-form analytical solution on the instability criterion. Whether shear instability occurs or not，some parameters，such the length of specimen，shear elastic modulus，shear softening modulus，internal length parameter (or the width of shear band) and the inclination angle of shear band，play important roles. If the system exhibits class II behavior，the shear instability occurs surely. The proposed instability criterion can be used to analyze the instability of coal pillar，i.e. coal pillar rock burst. The advantage of adopting gradient-dependent plasticity to analyze the problem of uniaxial compressive test subjected to shear failure is that the width of inclined shear band is involved in the present model and the distributed shear strain in shear band can be obtained strictly. The reasonability of theoretical results is also discussed.

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APPLICATION OF EXTENICS THEORY TO EVALUATION OF TUNNEL ROCK QUALITY

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2003, 22 (05): -751 doi:
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[PDF 189 KB] (1032)

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The extension engineering method is combined with tunnel rock evaluation. In view of the variety and complexity of the factors influencing rock quality，the parameters reflecting the general rock engineering are taken into account for evaluation. On the basis of matter-element theory，extension set theory and dependent function calculation，a matter-element model calculating procedure is proposed. By practical calculation of the dependent degree to the quality classification of the tunnel rock，the Shibeiling tunnel rock is evaluated by extenics. Compared with the evaluation results by the former “RMR” method，the rock quality evaluation results obtained by the extenics method can more precisely reflect the engineering characteristics of tunnel rock.

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HETEROGENEITY OF ROCK AND THE DEFINITION OF
YOUNG′S MODULUS

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2003, 22 (05): -757 doi:
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[PDF 279 KB] (1974)

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The experimental results of rock specimens in laboratory are dispersive to identify the property of rock mass. The Young′s modulus is various with the definition method. Specimens from rock strata are of micro-fissures resulting from the triaxial extension effect in drilling process. The fissures will close and slip at the initial step of uniaxial compression，which causes large amount of axial deformation. So the secant modulus from zero stress can not describe the deformation property of the practical rock mass. The average modulus，which is determined from the average slope of the more-or-less straight-line portion of the axial stress-strain curve，is less influenced by the experimental conditions. But the calculation method is not clear. In this paper，the maximum secant modulus is suggested，which is the maximum of all secant modulus with stress difference of 50% strength of the specimen. And also，the specimens from rock core are contacted in line，so it is better to use the harmonic average of specimens′ modulus，not the arithmetic average，as the mean modulus of the rock stratum. The harmonic mean method of Young′s modulus can express the great influence of soft seam on the deformation property of the whole stratum.

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PREDICTION OF ROCKBURST BY ARTIFICIAL NEURAL NETWORK*

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2003, 22 (05): -762 doi:
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[PDF 204 KB] (2348)

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Based on the analysis of main causes of rockburst，the compressive strength，tensile strength，elastic energy index of rock and the maximum tangential stress of the cavern wall are chosen as the criterion indexes for rockburst prediction. A new approach using neural method is proposed to predict rockburst occurrence and its intensity. The prediction results show that it is feasible and appropriate to use artificial neural network model for rockburst prediction.

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EFFECT OF BOLT IN JOINTED ROCK MASS UNDER MIXED
LOADING OF TENSION AND SHEARING

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2003, 22 (05): -769 doi:
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[PDF 274 KB] (1209)

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After analyzing the interaction mechanism between the rock mass and bolt in jointed rock mass，with the help of fracture mechanics method，the effect of bolt on stress intensity factor in joint tip under the mixed loading of tension and shearing is analyzed. Furthermore，the regularity of bolt effect under different loadings，different inclinations of bolt to the joint is revealed. The results demonstrate that the bolts alternate the stress intensity factors in joint tip and decrease the magnitude of stress intensive factor to affect rock failure. This may be the main reason that bolts reinforce the jointed rock mass.

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MECHANICAL MECHANISM OF REINFORCING SHAFT-WALL WITH PRESSURE RELEASE AND CASING-WALL METHOD
AND ITS ENGINEERING APPLICATION

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2003, 22 (05): -773 doi:
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[PDF 265 KB] (1007)

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The characteristic and mechanical mechanism of shaft failure under mega-thick alluvial surface layer are briefly analysed. Based on the mechanical mechanism of shaft failure，the pressure release and casing-wall method is applied to draw up the technical project to reinforce shaft and prevent it from failure. The construction characteristic，result and its practical value are presented in the light of an example of engineering.

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STUDY ON AERODYNAMICS EFFECT OF LARGE HIGHSPEED LANDSLIDE AT THE SHORT-RANGE STAGE

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2003, 22 (05): -778 doi:
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[PDF 305 KB] (1025)

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Many large highspeed landslides could fly in the air at the short-range stage. Highspeed sliding mass would bring about aerodynamic effect like the aerofoil. Based on the principle of aerodynamics，the aerodynamical effect is studied for the case of highspeed sliding mass flying in the short-range stage. The formula is educed for the flying parameters，including lift force，resitance force，flying time and distance in consideration of ground effect. The application of the formula to the Touzhai landslide in China gives reasonable results by comparison with the field observations. The calculated results illustrate that the lift force plays an important role in the motion of the sliding mass in the short-range stage，and the flying time is longer and the distance is farther than those without consideration of gound effect.

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TESTING STUDAY ON AERODYNAMICS EFFECT OF
LARGE-SCALE AND HIGH-SPEED FLYING LANDSLIDE

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2003, 22 (05): -784 doi:
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[PDF 357 KB] (1062)

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The aerodynamic effect must be taken in account for the analysis of landslide with large-scale and high moving speed. Based on wind tunnel testing of four models and applying aerodynamics theory，the rule of aerodynamics effect on the motion of landslide is studied. The differential equation of high-speed sliding mass flying in the short-range is put forward，and several important conclusions are obtained.

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DESIGN AND INSTALLATION OF COMPREHENSIVE INSTRUMENTATION SYSTEM FOR SLOPE IN HONG KONG

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2003, 22 (05): -790 doi:
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[PDF 432 KB] (8341)

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In order to clarify some of the important issues on slope performance，a full-scale slope monitoring experiment has been conducted at a being constructed slope，Hong Kong. The experiment adopts a number of instruments，including soil moisture probes，tensiometers，open standpipes，piezometers，inclinometers，earth pressure cells，and a rain gauge，etc. A high proportion of instruments are connected to dataloggers for automatic monitoring of the slope performance. The design and installation of the instrumentation system for the slope monitoring experiment are presented in detail.

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TESTING STUDY ON SHOCK COMPRESSION
FOR LANTIAN GRANITE

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2003, 22 (05): -797 doi:
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[PDF 509 KB] (1230)

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The testing study on dynamic property of rock under high strain rate is of important significance for national defence and civil construction. The testing data of Hugoniot are presented for Lantian granite under pressure range of approximately 78 MPa to 5.2 GPa. The test was conducted on a single-stage light gas gun of 57 mm. The general impact experimental configuration and the reverse ballistic experimental configuration with electro-magnetic particle velocity gage were used to obtain shock velocity and particle velocity. Lantian granite is different with others in acoustics and dynamics. There is a corner for the relation between shock velocity and particle velocity under about 0.47 GPa，and the result is well in accord with that of spherical divergent wave in Lantian granite. The ferromagnetic effect of Lantian granite is very strong. Electromagnetic field is excitated by shock wave. The electromagnetic field can severely disturb particle velocity signals. The reverse ballistic experimental configuration can effectively decrease the disturbanc and it is a very good method for testing study on the dynamic property of rock

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WAVE THEORY WITH HEAT EFFECTS IN POROUS MEDIA

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2003, 22 (05): -803 doi:
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[PDF 631 KB] (1287)

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The rheologic model is adopted to describe visco-elastic attenuation in saturated porous rocks and the modified Debye’s equation with real and imaginary modulus is obtained. Arrihenius equation is used to describe thermo-activated relaxation. Based on the assumption that porous materials follow Debye’s equation and Cole-Cole distribution law. Arrhenius equation is combined with local fluid model to obtain the temperature on peak frequency. The wave model with heat effects in porous media is obtained when introducing peak temperature into Debye’s equation. For this purpose it is discussed how the activation energy affects complex modulus changing with temperature and frequency. The control method is gained to establish the modified objective function，and annealing simulation and Monte Carlo algorithm are used to do inversion on the model. Verification with low frequency resonance data shows that the model is fine and the result can be a basis of low frequency modification on Biot’s theory.

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MECHANICAL ANALYSIS ON THE STABILITY
OF DEEP FURROW PIT SLOPE

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2003, 22 (05): -810 doi:
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[PDF 206 KB] (1073)

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The space effect of the furrow pit slope is analysed by elastic mechanics principle. The relation formula among the critical slide angle，the friction coefficient，the elastical modulus in circular direction of the circular rock，and the horizontal radius of the furrow pit is derived under the conditions，in which the rock mass is homogeneous and elastic，and loaded only by its dead weight and excavated like the reverse frustum. The relation formula shows that the deeper the furrow pit is excavated，the greater the critical slide angle is. Based on the relation formula both the theoretical basis for reducing stripping in furrow pits and the basic way to determine the figure of the stable slope are developed. The theory not only includes the conventionl principles for analysing the stability of slopes but also is available for analysing the stability of furrow pits. The great economic efficiency may be obtained by using the camber curve as the figure of furrow pits.

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ANT ALGORITHM IN SEARCH OF THE CRITICAL SLIP SURFACE IN SOIL SLOPES BASED ON STRESS FIELDS

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2003, 22 (05): -813 doi:
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[PDF 381 KB] (1186)

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Based on the researches on the nonlinear finite element analysis of stress fields in soil slopes，the nonlinear finite element techniques for analysis stability of soil slopes is integrated with a ant algorithm，which is a new optimization method of artificial intelligence. The ant algorithm optimization technique is used in search of the non-circular slip surface associated with the minimum safety factor of soil slope based on its stress fields from finite element analysis. Finally the feasibility of the technique is demonstrated with an example of stability analysis.

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RESEARCH ON DISPLACEMENT CRITERION FOR COMPOUND
ROCK MASS SLOPE AFFECTED BY GROUNDWATER

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2003, 22 (05): -820 doi:
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[PDF 224 KB] (1048)

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According to bifurcation specificities of displacement for compound rockmass slope affected by groundwater，the displacement formulas for rockmass slope in the process of progressive failure are derived，and the sufficient condition for the sudden instability of rockmass is given. In accordance with the characteristics and mechanism that groundwater softens rockmass of slide surface by physicochemical effect，the catastrophic displacement criterion for slope is established.

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TESTING STUDY ON THE CORRELATION AMONG LANDSLIDE，DEBRIS FLOW AND RAINFALL IN JIANGJIA VALLEY

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2003, 22 (05): -824 doi:
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[PDF 647 KB] (1196)

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The special landslides with slide and collapse in Jiangjia debris flow valley is studied. A large-scale landslide test and model test were conducted in site excited with artificial rainfall. The moisture content of slope was measured in the tests，and the surface erosion，collapse and slide，and transfer from landslide into debris were analysed. The correlation among rainfall，landslide and debris flow is revealed with the moisture content distribution changed.

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SPECIAL PROBLEMS OF ENGINEERING GEOLOGY AND ROCK MECHANICS IN THE WEST ROUTE OF SOUTH-TO-NORTH WATER TRANSFER PROJECT

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2003, 22 (05): -829 doi:
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[PDF 267 KB] (892)

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The strategic West Route of South-to-North Water Transfer Project locates in sharp cold area of China. The special problems of engineering geology and rock mechanics existing in the project，such as active faults and related issue of tunnel faulting，potential disaster of debris flow，high pressure water flow and debris flow in the tunnel，high earth temperature induced deterioration of rock properties，high in-situ stress and its variation tendency，rock mechanics problems related to TBM，and the potential regional changing in geological environment，etc，are challenging for the geotechnical engineers. It is difficult to reveal and estimate the potential disaster for the project. The particular problems and some of the disaster results are discussed，and the guideline for further investigation is proposed.

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DATABASE AND DYNAMIC DISPLAY SYSTEM FOR SHIELD TUNNELING MONITORING

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2003, 22 (05): -834 doi:
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[PDF 198 KB] (953)

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The functions and structure of the database and dynamic display system are presented for shield tunneling monitoring. The functions and usage of some powerful visualized database explorers are described in detail. The system can be used in technical management and comparison analysis of construction，monitoring，supervision and designing of shield tunnel. It can greatly increase productive efficiency.

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STRESSES ANALYSIS OF SURROUNDING ROCKS BASED ON THICK
CYLINDER AND ANISOTROPIC DAMAGE THEORY BY
FINITE ELEMENT METHOD

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2003, 22 (05): -838 doi:
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[PDF 265 KB] (924)

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The stress distribution of surrounding rocks is of great influence on stability of tunnels. Based on anisotropic damage theory，an axisymmetric FEM program was developed to study stress distribution of a thick cylinder under outside compression. Gradient of tangential stress increases along with the increase of brittle index of rocks，and the maximal tangential stress occures at some distance from the inner surface of the cylinder. The mechanism of the phenomenon is explained that the slices are exfoliated from surrounding rocks with different thickness

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3D FEM ANALYSIS ON NEW-STYLE PRESTRESSED ANCHOR SHEET-PILE RETAINING WALL

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2003, 22 (05): -843 doi:
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[PDF 336 KB] (1060)

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After comparison with gravity retaining wall and railway bridge，the new-style prestressed anchor sheet-pile retaining wall was selected to meet the request of laying triple-track on 40 m wide platform at rock slope of 30°. An existing 3D FEM program is improved and used to calculate the displacements，internal forces and moments of the surface pile，the displacements and stresses of the anchorage part，the earth pressures of filler，and the tension forces of anchored cabl. In comparison with other methods，such as geologic mechanics model test in laboratory，prototype observation and 2D FEM analysis，the presented calculation results seem more reasonable and can be a reference for engineering design and construction.

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FORECASTING MODEL OF SAFE COVER THICKNESS OF
TUNNEL CROSSING SONGHUA RIVER IN HARBIN

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2003, 22 (05): -849 doi:
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Aimming at the construction process of Songhua river tunnel which will be built recently，the finite element numerical model is used to solve the actual problem of tunnel for 40 different cases and various proposed sites. The simulation is conducted repeatedly. On the basis of simulated results，the curves between single factor and safe cover thickness are drawn and the high precision fitting relations are given，so that the laws between single factor and safe cover thickness are studied. The main factors affecting the safe cover thickness are singled out. Stepwise regression analysis method is adopted to obtain the forecasting model on safe cover thickness of tunnel and is capable of synthetic embodying the combination action of all main affecting factors. At last，the reliability and efficiency of the model are verified by a calculation example of underwater tunnel.

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APPLICATION OF INFRARED ACQUISITION TECHNOLOGY IN PREDICTION OF WATER GUSHING IN YUANLIANGSHAN TUNNEL

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2003, 22 (05): -855 doi:
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[PDF 196 KB] (1047)

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Water gushing is a major geological problem in tunneling practice，which will cause hidden trouble during construction. Therefore，water gushing prediction in dangerous zone is a useful measure for safety guarantee. The basic principles of model HY-303 infrared acquisition meter and application prospect in water gushing prediction in Yuanliangshan tunnel are described. The application results in Yuanliangshan tunnel entrance show that infrared acquisition meter is feasible in water gushing prediction in water-bearing strata，and of a good application future in tunneling in complex geological conditions.

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STUDY ON THE STRENGTH ENHANCEMENT OF
HUMID-PLASTIC CEMENT SOILS

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2003, 22 (05): -858 doi:
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[PDF 263 KB] (973)

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Based on the application practice of cement soils into the highway engineering，the mechanism of the solidification and strength forming process of the humid-plastic cement soils are studied. The cement-soils are classified for highway engineering and the forming method of the humid-plastic cement-soils is proposed. The strength forming process of humid-plastic cement-soils is expatiated based on the characterization of the cement hydration process in cement-water-clay system. The enhancing effect of the additives and mineral admixtures on the humid-plastic cement soils and the suitable additives dosage are studied. The effect mechanism of the additives and admixtures on the strength forming of humid-plastic cement soils is discussed also.

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LABORATORY TESTING STUDY ON THE STRENGTH REGULARITY
OF WENZHOU SOFT CEMENT-SOIL

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2003, 22 (05): -863 doi:
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[PDF 175 KB] (929)

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Through orthogonal laboratory testing of compressive strength for Wenzhou clay cement-soil and Wenzhou muck cement-soil，the special strength regularity of cement-soil is studied，and some new knowledge of cement-soil is obtained. For instance，at the same condition of admixture and age，the compressive strength of clay cement-soil is higher than that of muck cement-soil，but the differense value is little at low age. In high admixture，there is no evident relation between the strength difference and age of different cement-soils.

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ANALYSIS，SIMULATION AND APPLICATIONS
OF WATER INRUSH SYSTEM IN MINE AREA

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2003, 22 (05): -866 doi:
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[PDF 101 KB] (834)

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