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2004, 23 (11): -0 doi:
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TWO-DIMENSIONAL ANALYTIC EXPRESSION ON STRAIN LOCALIZATION OF ROCK BY STRAIN GRADIENT PLASTICITY THEORY

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2004, 23 (11): -1785 doi:
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Plastic strain gradient increment constitutive model in small strain plastic deformation is established by introducing the internal length of material to yielding function. The analytic expression of equivalent strain of rock under uniaxial compression and two-dimensional plane stress is presented. The relational formula between strain localization band width of rock and its inclination angle in plane stress is derived based on Mises’ yielding criterion. The distribution range of strain localization band is discussed and the forming conditions of maximal and minimal values are presented. I and II type deformation conditions of rock are discussed and the critical angle of failure is further derived. Detailed analysis is made on I type deformation of rock. The changing range of the inclination angle of strain localization band under different v and E／l is discussed. At last，by using the conclusion from the strain gradient plasticity theory and the Coulomb-Navier criterion on material failure，the contrast studies are made and reasonable explanations are given on coefficient of internal friction.

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RELATION BETWEEN PORE LIQUID PRESSURE AND BULK
ELASTIC MODULUS OF LOADED SATURATED ROCK OF LOW PERMEABILITY

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2004, 23 (11): -1792 doi:
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The structure of saturated porous body with low permeability deforms under uniaxial compression load and the liquid in porous is compressed also. The part of compressed pore liquid penetrates throughout the micropipe of body. The pore liquid pressure supporting load is reduced and the load is moved to the solid structure. Thus the equilibrium takes place finally after a serious loading redistribution，reduction of pore pressure and increment of structural deformation. In present paper，the variation progress of pore pressure and structural deformation in saturated weak rock，and changes of saturated bulk modulus are given，which are confirmed by the results of experiments.

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CATASTROPHE THEORY ANALYSIS ON ROCKBURST IN
NARROW COAL PILLAR

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2004, 23 (11): -1797 doi:
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[PDF 310 KB] (1007)

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Based on the simplified analytic model of rockburst in narrow coal pillar，the catastrophe model of rockburst in narrow coal pillar，the fold catastrophe model can be educed by equilibrium relation of work-energy increment from energy conservation principle. All the characteristics，demonstrated by the equilibrium equation and its equilibrium path of catastrophe model，can be used to describe the main behaviors of failure process in coal pillar with the forms of rockburst and gradual damage one by one correspondingly. The variation rate curve of elastic energy of rock beam，which includes abundant information，is given for the first time，which is of great significance for understanding the behavior and law of rock beam-coal pillar system in each phase. The presented study results show that energy importing rate J = 0 is the critical condition of system destabilization，which implicates Cook stiffness criterion and is a dynamic generalization of Cook criterion in the form of energy.

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FUZZY REASONING SYSTEM OF PILLAR STABILITY BASED
ON SONIC WAVE MEASUREMENT AND ITS APPLICATION

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2004, 23 (11): -1804 doi:
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The relationship between wave velocity and load in a pillar，and corresponding relationship between fracture zone and wave velocity distribution are analyzed. The fuzziness of wave velocity and stability of a pillar is also discussed. Furthermore，fuzzy reasoning system is established using fuzzy mathematical theory. In the system，rock integrality coefficients are used as input variables and stability of pillar and possibility of partial failure of pillar are used as two output variables. The system is applied to Suichang Gold Mine in Zhejiang province and good results are obtained even if measurement points are not enough.

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DEFORMATION RULES AND ACOUSTIC EMISSION CHARACTERISTICS OF ROCKS IN PROCESS OF FATIGUE FAILURE

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2004, 23 (11): -1810 doi:
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Deformation rules and acoustic emission characteristics of rocks in the process of fatigue failure are studied and the relation of them is revealed using the rock mechanics test equipment named RMT-150B and Locan320 acoustic emission instrument. The elementary analysis for the process of fatigue failure of rock is carried out from the points of macroscopical irreversible deformation and microcosmic damage. In addition，three-stage laws of axial deformation and two-stage laws of radial deformation are established and the rationality to choose axial deformation as macroscopical damage parameter is also presented.

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ANALYSIS ON FAULT ROCKBURST CONSIDERING EFFECTS OF WATER WEAKENING AND STRAIN GRADIENT

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2004, 23 (11): -1815 doi:
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Stability analysis is made on the system composed of fault band and surrounding elastic rockmasses considering water weakening and strain gradient. The deformation of ductile fault after rock burst is investigated. It is found from experimental measurement that the shear strength and the absolute value of the slope of stress and strain curve are decreased with water content. Considering the deterioration of strength，the distribution rules of plastic shear strain and total plastic shear strain in shear band are proposed based on gradient-dependent plasticity. Besides，the relation between shear force and relative plastic shear displacement is also presented. The analytical result shows that the plastic shear strain and the plastic shear displacement decrease with water content. Larger water content leads to shorter elastic stage，lower dissipated potential energy and lower external force work. In addition，the released elastic strain energy increases as water content decreases. According to the analytical solution of axial stress-axial strain curve of rock specimen in uniaxial compression proposed by authors and experimental results，water content affects the softening modulus. The post-peak slope of shear stress and shear displacement curve of the system is presented considering the influence of water content on the softening modulus. It is shown that increment of water content reduces the possibility of instability.

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INFLUENCE OF ROCK CELL CHARACTERISTICS AND ROCK INHOMOGENEITY PARAMETER ON COMPLETE CURVE OF STRESS-STRAIN

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2004, 23 (11): -1819 doi:
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Through numerical experiment method，the influence of rock cell characteristics and rock inhomogeneity parameter on the character of the complete stress-strain curve under uniaxial compression is studied with rigid testing machine. Rock cell characteristics reflect the relationship between stress and strain，such as pure-elasticity，elasto-plasticity，strain-softening and strain-hardening. The material in each element is treated as homogeneous and is not the same as other element. The elastic constants and failure strength are randomly assigned according to Weibull distribution. The inhomogeneity parameter ‘m’ reflects the initial heterogeneity of distribution of material properties. The study result indicates that rock inhomogeneity parameter, m, is the decisive factor of complete curve character under uniaxial compression with m≥6. On the contrary，with m＜6，the rock cell characteristics are the decisive factor of complete curve character under uniaxial compression. The difference between peak and residual strength of rock sample is increased with the difference of corresponding rock cell.

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CONTRAST ANALYSIS ON 2D AND 3D PERSISTENCE PROPERTY OF JOINTED ROCK MASS

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2004, 23 (11): -1824 doi:
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It is first confirmed in theory that two dimensional distribution of joint trace revealed in an outcrop plane (2D) or in a hole (1D) does not represent three dimensional (3D) distribution of discontinuity with limited size in real rock masses. So a real three dimensional problem of rock masses containing discontinuities with limited size should not be simplified to a two dimensional problem. The contrasts between 2D persistence ratio and 3D persistence ratio of calculation results of two examples are in a good accordance with the results of theoretical analysis.

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INVERSE STUDY ON OCCURRENCE OF DOMINANT TEXTURE PLANE IN JOINTED ROCKMASSES

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2004, 23 (11): -1832 doi:
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[PDF 263 KB] (952)

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According to the manner of engineering geology，the texture plane is described with vector in the natural coordinate system. The intersecting relation of the sampling windows with the texture plane is studied. The local coordinate system is set up on sampling windows and the transition group of the vectors describing texture plane in two kinds of coordinate systems is deduced. The occurrence parameters of texture plane are back calculated from the intersection angles of the sampling line and texture plane traces in the sampling windows on the basis of the relation and peculiarity of group by least square method. This method requires a few site data and is easy to operate and simple to be applied to engineering practice.

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AUTOMATIC MESH GENERATION AND NUMERICAL ALGORITHM OF
NUMERICAL MANIFOLD METHOD

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2004, 23 (11): -1836 doi:
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[PDF 231 KB] (1439)

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In the numerical manifold method developed by Genhua Shi，two types of mesh systems，mathematical covers and physical covers，are involved. Mathematical covers constitute the whole interpolation domain while physical covers are used to define the integral domain. Pre-process of computational model used for numerical manifold method is usually difficult in practical applications. Although some efforts have been made in past，there is lack of efficient solving algorithms. Therefore，a computer-based technique of automatic mesh generation especially adapted for numerical manifold method is developed in this paper. In the proposed method，mathematical covers are kept to be invariants independent of the constitutive media which may continuous or discontinuous. Mathematical meshes of numerical manifold method can be automatically generated by using the same mesh-generation technique as employed in finite element methods while physical meshes are generated by virtue of objective-oriented programming. An effective algorithm is presented for implementation of the proposed technique. It is shown through an example analysis that both the proposed technique and numerical algorithm are practically feasible and effective for the numerical manifold method.

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AUTO-GENERATEING GRID ON JOINT NETWORK MODEL FIGURE BASED ON CONSTRAINT DELAUNAY TRIANGULATION

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2004, 23 (11): -1841 doi:
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After analyzing and classifying the wide variety of mesh generation methods for finite element computation，a clear overall picture of all those methods is provided. Performances of Delaunay triangulation are campared，and the merits and disadvantages of exisiting methods in auto-griding on joint network model figure are also discussed. Additionally，a method based on constraint Delaunay triangulation can be available as a substitute. In the method，all joints are treated as characteristic constraints. Based on Delaunay triangulation on disperse points，all constraints are inserted one by one，and then refinement method is employed to make grid denser to meet the precision quest in numerical computation.

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APPLICATION OF RESPONSE SURFACE METHOD TO RELIABILITY ANALYSIS OF MONOLITHIC LINING OF RAILWAY TUNNEL

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2004, 23 (11): -1847 doi:
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When there is large number of samples of characteristic parameters，the Monte-Carlo method is a comparatively accurate method to compute reliability of structure. However，in underground engineering，available samples of those characteristic parameters are quite limited in quantity，so it is more practical to use response surface method instead. In the light of monolithic lining structure of railway tunnel，the results from response surface method are analyzed and compared with those from 100 000 samplings by Monte-Carlo method. It is found that the two methods are mutually in good agreement on all sections except the place where the bending moment is approximately zero，which shows that response surface method is feasible to calculate reliability of railway tunnel lining.

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FUZZY-SYNTHETICAL EVALUATION ON STABILITY OF SURROUNDING ROCKMASSES OF UNDERGROUND ENGINEERING

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2004, 23 (11): -1852 doi:
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The stability of surrounding rockmasses are affected by several uncertain factors with random and fuzzy behavior. Several key factors affecting stability of surrounding rockmasses are selected and the subordinate functions and index values of these factors are determined. Then the stability of surrounding rockmasses are estimated by the method of fuzzy-synthetical evaluation. The method is applied to a practical project and several conclusions are derived.

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ANALYSIS ON KEY LAYER OF OVERLYING STRATA
WITH ELASTIC SLAB THEORY

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2004, 23 (11): -1856 doi:
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Under the guidance of key layer theory in strata control，the conditions of stiffness and strength for key layer are established by using elastic slab theory. The study result shows that the same expression can be obtained both from slab theory analysis and rock beam analysis. Finally the existence of key layer of overlying strata is proved with practical example.

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STUDY ON ELECTRICAL PROPERTIES OF ROCK-COAL
POROUS MEDIA WITH GAS

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2004, 23 (11): -1861 doi:
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Coal-rock electrical properties are very important，which reflect coal inner structure and ingredients，and vary obviously when coal is pressed or destroyed. In the paper，the alternative characters of current electric conduction of rock-coal porous medium with gas are studied. It is concluded that the conductivity increases along with gas pressure，and conductivity of coal without gas is smaller than that of coal with gas，the conductivity increases along with temperature whether the coal contains gas or not，and the conductivity of coal with gas is bigger than that of coal without gas under same conditions. The conductivity is not variated with the voltage of alternative electric field. The conductivity increases along with the frequency of alternative electric field，and the relationship between conductivity and the frequency is fractal one. It is possible that coal and gas outburst can be predicted by monitoring the variation of coal conductivity along with the gas pressure or coal temperature.

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STABILITY ANALYSIS OF SOIL SLOPE BY FINITE ELEMENT METHOD WITH PLASTIC LIMIT UPPER BOUND

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2004, 23 (11): -1867 doi:
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The theory and method of the plastic limit analysis are introduced systematically. By using the finite element method and linear program，the upper limit method can evaluate the bearing capacity and the safety factor of soil slope. The influence of yield surface linearization on the degree of accuracy and the influence of slope soil density on the limit load are discussed. A classical slope calculation case show that the presented method is of correctness and high precision.

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DYNAMICS AND STABILITY CRITERION OF OBLIQUE LAYERED ROCKY LANDSLIDE UNDER LOCKUP WITH COMBINATION OF FLANK AND BEDDING PLANE

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2004, 23 (11): -1874 doi:
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Oblique-layered rocky landslide under lockup with combination of flank and bedding plane is a new type of deformation and failure of slopes. For the oblique slopes of layered rocks，the dips of layered rocks and slope intersect each other，the angle between the strike of layered rocks and the strike of slope is more than thirty degrees，and the dip angle of the layered rocks is greater than ten degrees. Generally the progressive failure is developed of oblique-layered rocks at the pre-failure stage. In plane，one of flanks is free due to the preexisting fault and subsequent erosion by water，and another flank on the middle part of the deformed layered rocks is connected with undisturbed rocks. In addition，the oblique-layered rocks spin asymmetrically around an axis perpendicular to the potential slip surface near the middle locked segment of the flank. On cross-section，along the potential slip surface，the deformed layered rocks are not completely sheared through the surface，and the downslope movement in the layered rocks decreases gradually from outside to inside where sliding is impeded. So according to the behavior of the layered rocks，pre-failure deformation of landslide can be described by bending of multilayered rectangular plates with two adjacent edges fixed and the other free under combined transverse and lateral loads，and the onset of failure of landslide can be viewed as buckling-bending and critical rupture of the plates. By means of Rayleigh-Ritz energy methods，an equation of elastic deflection-load of plate is established，and then the ultimate bearing capacity of plate is determined with the approach of plastic limit analysis. Consequently，a stability criterion of landslide is deduced and a case is analyzed，which is proved to be effective in the quantitative stability evaluation of this kind of landslide.

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DYNAMIC STABILITY ANALYSIS OF HIGH FILL SLOPE OF
JIUZHAI-HUANGLONG AIRFIELD

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2004, 23 (11): -1883 doi:
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Jiuzhai-Huanglong airfield is located in high mountain-narrow valley area of the eastern fringe of Tibet plateau，about 450 km far from the northwest of Chengdu. The airfield is on the accumulated terrace of Min river and goes through five large scoured gutters. The maximum height of the fill slopes reaches 102 m and the total cubic meter of earth and stone exceeds 4×107 m3. The structure of the ground made of quaternary river sediments，which contain sand layers，pebble layers，sandy clay，conglomerate rock and mudrock，is complicated and its mechanical behavior varies greatly. There are three active faults near the airfield with earthquake intensity Ⅷ. A numerical method combining three dimensional finite element method with pseudostatic analysis is employed in the dynamic stability analysis of the high fill slope. The results reveal that under earthquake with intensity Ⅷ，the possibility of integral slide of high fill slope is small，but the slope maybe fails disassembly. The fill slope stability is more sensitive to the earthquakes from Min river fault than that from Xueshan fault，which is controlled mainly by the boundary conditions of the fill body.

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MAXIMUM LIKELIHOOD ESTIMATION ON SAFETY COEFFICIENTS OF ROCKY SLOPE NEAR DAM OF FENGTAN PROJECT

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2004, 23 (11): -1891 doi:
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[PDF 221 KB] (989)

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The factors，which control and affect slope stability，are random and fuzzy variables, so that the maximum likelihood estimation methods are available to solve the uncertain problems，like the estimation of slope stability. Based on the assumption of circular slip surface，the safety coefficients of slope near dam of Fengtan project are obtained with the maximum likelihood estimation methods and the results are compared with theose from limit equilibrium method. According to the computing results and analyses，it is showed that the maximum likelihood estimation methods are of practical values for estimation of slope stability.

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RECOGNITION OF MODELS AND BACK ANALYSIS OF PARAMETERS FOR ARTIFICIAL FROZEN SOILS

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2004, 23 (11): -1895 doi:
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[PDF 286 KB] (865)

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Based on frozen soil creep tests，yield stress limit is approximately determined by means of experimental tautochrone at first. Then several visco-elastic and visco-elasto-plastic rheological models are established. The model parameter are feed back by the non-linear least square method. A fuzzy optimization model is developed under the principle of simplicity and accuracy. As a result，the optimal model is Burgers model under the lower stress level or H-H/N/S model under the higher stress level.

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SIMPLIFIED SEISMIC ANALYSIS METHOD OF
SOFT SOIL SSI SYSTEM

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2004, 23 (11): -1900 doi:
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[PDF 301 KB] (782)

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A simplified seismic analysis method of soft soil SSI system is studied in this paper. Based on the earlier stage tests and FEM analysis，a simplified dynamic model with small relative dynamic stiffness ratio of soil to superstructure is put forward，and the inversion solution of model parameters is presented. The seismic analysis method of soft soil SSI system with simplified dynamic model is derived. By comparison of computational solution and test result，the thought of simplified modeling is confirmed.

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ANALYSIS ON SAFETY COEFFICIENT AND FAILURE MODEL OF SUPPORT SYSTEM FOR DEEP FOUNDATION PIT OF RUNYANG BRIDGE

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2004, 23 (11): -1906 doi:
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The size of the north anchor pit of Runyang Bridge is about 69 m×50 m×50 m. The support for this pit is concrete diaphragm wall with internal support structure，and the diaphragm wall is embedded into rocks. In order to obtain the safety coefficient and the failure process of this pit，3D nonlinear finite element analysis is carried out with ANSYS. The excavation process is simulated with the “element dead/active” function of ANSYS. The self-weight of soil in finite element model is increased hypothetically until support structure fails，so that the failure process of support structure can be simulated. Comparing the assumed self-weight of soil with the true value，the safety coefficient of the pit can be obtained. The numerical results show that all the failures of the pit begin with the collapse of the internal support and the failure models are different in various excavation depths. This method can also be applied to the other pits if their support structure is relatively stiff.

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EFFECT OF PASSIVE REINFORCEMENT OF SOIL ON DISPLACEMENT CONTROL OF PILES SUBJECTED TO ADJACENT SURCHARGE LOADS

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2004, 23 (11): -1912 doi:
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When surcharge loads are larger than the allowable bearing capacity or displacement at the top of piles is beyond the control criterion of displacement，reinforcement of soil should be implemented to enhance the stability and control the lateral displacement of piles. Deep mixing soil is one of the available and common reinforcement approaches. By finite element analysis on the interaction between soils，reinforced by cement-mixed soil in the passive zone，and the piles subjected to adjacent surcharge loads，the effect of width，depth and elastic modulus of cement-mixed soil on displacement control of piles is discussed and then some valuable conclusions are drawn for practice in ground treatment.

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STUDY ON GAOFENG MINE TREMOR AND ITS CURING MEASURES

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2004, 23 (11): -1919 doi:
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[PDF 492 KB] (672)

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2004, 23 (11): -1924 doi:
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[PDF 625 KB] (871)

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QUALITY CONTROL AND MANAGEMENT OF TBM CONSTRUCTION

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2004, 23 (11): -1930 doi:
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[PDF 197 KB] (1135)

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TBM is a very complex system that involves machinization，automatization and modern management，so it is very important to manage and control the key links of this system with high quality. In the Tunnel No.7 of YRDP ICB Connection Works，the request of control and management is very strict about the tunnel excavation axis，segment production，segment installation，pea-gravel backfill，grouting and monitoring. The measures to meet the request are presented and they are good reference for other similar projects.

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STUDY ON BENDING STIFFNESS OF REINFORCED CONTINUOUS CEMENT-SOIL WALL

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2004, 23 (11): -1935 doi:
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The working mechanism of reinforced continuous cement-soil wall is described，and it is pointed out that the cement soil can share load and make contribution to the stiffness of continuous wall structure. The behaviour of cement soil is varied with applies load. The deforming process of reinforced continuous cement-soil wall under the load is divided into 5 phases. The evolution of efficient section and stress distribution in every phase is analyzed. The stiffness formula of continuous wall is derived and proved by test.

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STABILITY ANALYSIS OF COVER SOIL SLOPE ON WASTE LANDFILL UNDER SEEPAGE WITH LIMIT EQUILIBRIUM METHOD

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2004, 23 (11): -1939 doi:
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[PDF 265 KB] (932)

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Stability analysis is made with limit equilibrium method for the cover soil slope on waste landfill under seepage. The parameters of design are correctly taken into account and it is considered that seepage reduces the interface friction angle，and water pressure at interface decreases friction force. The analysis result keeps good agreement to practical case，and it is proposed to design an adequate drainage system to decrease the water pressure at the geosynthetic interface.

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SIMULATIVE CALCULATION ON DISTRIBUTION OF LEACHATE OF WASTE LANDFILL THROUGH SOIL

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2004, 23 (11): -1944 doi:
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[PDF 239 KB] (877)

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In this paper，the distribution equation of leachate of waste landfill is built，and the testing method is put forward to determine diffusion coefficient of waste pollutant. Using finite element method，the stationary and dynamic analysis is made on the distribution of pollutant intensity. After obtaining sufficient data，the pollution of landfill leachate on surrounding soil can be forecasted.

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RESEARCH ON FATIGUE BEHAVIOR OF CEMENT-SODIUM-SILICATE-GROUTED SOIL

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2004, 23 (11): -1949 doi:
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The fatigue behavior of cement-sodium-silicate-grouted soil is investigated by cyclic loading test of dynamic asymmetric sine wave load. Because of the progressive deformation of cement-sodium-silicate-grouted soil under cyclic load，the cement-sodium-silicate-grouted soil is damaged under a lower stress level. The fatigue life of cement-sodium-silicate-grouted soil is considerably affected by loading amplitude and frequency，but the effect of former is stronger than that of latter.

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INFLUENCE FACTORS ON STRENGH OF DEEP-MIXING PILE AND IMPROVEMENT MEASURE

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2004, 23 (11): -1954 doi:
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[PDF 229 KB] (1307)

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The main influence factors on strength of deep-mixing pile are the actual ratio of cement to soil，curing time of cement，water content of soil，homogeneity degree of cement-soil，mixing depth，additive confining pressure of soil，and cement strength. All the influence factors are analyzed and available measure is proposed to improve the bearing capacity of single pile and the strength of deep-mixing pile .