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INTERVAL BACK ANALYSIS ON UNCERTAIN PARAMETERS
IN ROCK MECHANICS

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2004, 23 (06): 885-885 doi:

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Due to the uncertainty of measured data，rock mechanics parameters are often considered as unknown but bounded variables in intervals. An interval back analysis approach is presented in this paper to identify the mechanical parameters of rocks. The intervals of mechanical parameters can be obtained by means of the flexible tolerance method. The effect of measurement precision and the number of parameter for the back analysis is illustrated. The application results show that the interval back analysis on uncertain rock mechanics parameters provides valuable information for rock engineering.

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DIGITAL IMAGE PROCEEDING BASED ON FINITE ELEMENT METHOD FOR GEOMATERIALS

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2004, 23 (06): 889-889 doi:

[PDF] 759 KB (1618)

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This paper presents an innovative digital image processing method based on a method to examine the mechanical responses of geomaterials by taking into account the actual material inhomogeneity. The proposed method incorporates the digital image processing procedures，geometry vectorization algorithms and automatic finite element mesh generation techniques into the conventional finite element methods. Using a granitic rock as an example, the paper illustrates the innovative numerical method for mechanical analyses of rock materials. Numerical results presented in the paper show that this method can be used to calculate the mechanical responses of inhomogeneous geomaterials with high efficiency and accuracy.

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UPPER LIMIT ANALYSIS OF STABILITY OF ROCK AND SOIL SLOPES USING RIGID FINITE ELEMENTS

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2004, 23 (06): 898-898 doi:

[PDF] 446 KB (1617)

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In this paper，the development and application of a new upper limit method for 2D and 3D slope stability problems are presented. Rigid finite elements are used to construct a kinematically admissible velocity field. The proposed method formulates the slope stability problems as an optimisation problem based on the upper bound theorem. The objective function for determination of the minimum value of the safety factor has some unknowns, which are subject to a set of linear and non-linear equality constraints derived from an energy-work balance equation，the Mohr-Coulomb failure (yield) criterion，an associated flow rule and a number of boundary conditions. The objective function with constraints leads to a non-linear programming problem， which can be solved by a sequential quadratic algorithm. Four typical 2D and 3D slope stability problems selected from the literature are analysed with the presented method. The results of the presented limit analysis are compared with those produced by other approaches reported in the literature.

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ANALYSIS ON SLOPE STABILITY OF SHENZHEN RESERVOIR

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2004, 23 (06): 906-906 doi:

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Analyses on local and global stability，slip displacements and catastrophic property of landslide of Shenzhen reservoir slope are given，and effect of groundwater and soil weakening property by water on slope stability is emphatically studied. Catastrophe of landslide of slope is analyzed by the use of catastrophic theory model. The calculated results of stability and displacements indicate that unstability of slope is mainly caused by groundwater affection and soil weakening by water，and catastrophic analysis also indicates that slip displacements increase sharply and slope unstability arises suddenly when shear strength of soil is reduced to certain value due to soil weakening. The theoretical results are in good agreement with those of in-situ test and are able to provide scientific basis for slope protection.

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SPATIAL PROBALITITY ANALYSIS OF LANDSLIDES BASED
ON GIS TECHNOLOGY

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2004, 23 (06): 911-911 doi:

[PDF] 375 KB (1075)

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Spatial stability of slope is important in many engineering problems. Research on the susceptible factors of landslides is needed for the estimation of slope stability. In this research, the GIS technology is useful and important to analyze the spatial probability of landslide occurrence. In this paper GIS is used to study the spatial features of landslides along the bank of Fengjie district in the Three Gorges region. The susceptibility of landslide triggering factors is analyzed by means of the slope certainty factors (CF). The results show that the presented method is useful to study spatial distribution and occurrence of landslides in future.

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APPLICATION OF GRAY CORRELATION ANALYSIS
TO ROCK SLOPE STABILITY ESTIMATION

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2004, 23 (06): 915-915 doi:

[PDF] 170 KB (1019)

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Based on the discussion of combined indices, which reflect the factors influencing rock slope stability，such as rock quality, structural faces of rock masses and slope geometry properties, the effectiveness of employing the gray correlation method to estimate the rock slope stability is validated through examples. The results show that the gray correlation analysis method can provide quantitative measures to geological-engineering analogy and it is practical and feasible to apply the five combined indices and gray correlation analysis method to estimate the rock slope stability.

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CASE STUDY ON INFLUENCE OF RAINFALL PERMEATION
ON SLOPE STABILITY

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2004, 23 (06): 920-920 doi:

[PDF] 274 KB (1599)

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Based on the case of the left bank slope of Jinghu pump station in Dongjiang-Shenzhen water supply remaking project, the factors influencing the slope stability are analyzed. The main causes of slope sliding are the soft rock strata in the slope and the large precipitation in this area. The water permeates into the slope body during the rain and can not be drained away quickly enough，so it concentrates under the concrete cover，and the rock is softened by it. Therefore，the safety factor of the slope decreases，and the slope begins sliding. Based on calculation of the stress, strain, and destruction approaching degree of the slope with the linear-elastic finite element method and Mohr-Coulomb yield criterion，a conclusion can be drawn that the slope in natural condition is basically safe，but，when the depth of the rainfall permeation increases，the destruction approaching degree near the slope surface increases，and the area of destruction increases gradually. The slope will develop from partial sliding to whole sliding.

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RELIABILITY STUDY OF COMPLEX SLOPE STABILITY ON SOFT SOIL

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2004, 23 (06): 925-925 doi:

[PDF] 275 KB (998)

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Based on the random field modeling of soil profile and the Bishop routine solution，the stability reliability of a practical complex slope behind waterproof wall is studied. By JC method，the reliability index of different improvement plan for soft foundation is respectively calculated. The influence of probabilistic property and cross-correlativity of soil properties on reliability index is analyzed. From the results of static cone penetration test，the self-correlation distance of and is estimated，and the influence of on slop stability reliability is investigated. The developed computer program on reliability of the complex slope stability is worked out and some valuable conclusions are drawn.

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IN-SITU TESTING STUDY ON PILE FOUNDATION IN SOIL SLOPE
UNDER HORIZONTAL LOADINGS

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2004, 23 (06): 930-930 doi:

[PDF] 254 KB (1166)

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In-situ horizontal loading tests of pile foundation for an eleven-storey building on a soil slope are carried out. Combining testing results with the physical and mechanical properties of the slope soil, and the parameters of piles, it can be concluded that (1) the foundation structure design controlled by displacement consideration for the building is safe，(2) the mechanical response of piles obviously changes with the variance of distance from a pile to the soil slope to some extents, and when the horizontal displacement of pile is known, the shorter the distance is，the greater the horizontal bearing capacity of a pile is，which reflects the fact that the piles closer to a soil slope are under the greater three-dimensional static pressures，and (3) the bearing capacity of a pile is not related to the relation between loading direction and the slope inclination direction. This means that the soil slope is of homogeneous property，which is different from rock slope with strong directional influence due to geological structures of rock mass.

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DECOMPOSITION OF POTENTIAL FUNCTIONS FOR DYNAMIC SOLID-FLUID COUPLING EQUATIONS OF LIQUID-SATURATED SOILS

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2004, 23 (06): 936-936 doi:

[PDF] 250 KB (949)

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By using potential functions of solid-phase and liquid-phase displacements, the dynamic solid-fluid coupling vector equations of liquid-saturated soil are decomposed into the decoupled equations of irrotational wave and isometric wave, so that the dynamic analysis is greatly simplified. Simultaneously, the cases in which porous water flows freely and does not seeps into soils are discussed and some very useful conclusions are obtained.

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BACK ANALYSIS ON ROCK MECHANICS PARAMETERS FOR
HIGHWAY TUNNEL BY BP NEURAL NETWORK METHOD

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2004, 23 (06): 941-941 doi:

[PDF] 299 KB (1268)

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The back analysis is made by means of the BP neural network algorithm on the mechanics parameters of surrounding rock masses in a highway tunnel construction project by NATM. The weight value matrices and tolerance vectors in accordance with input neurons and outputs can be obtained by training a set of specimens，which comes from a FEM analysis for a highway tunnel, the Pingshi Tunnel of the Beijing-Zhuhai expressway. The analogy results of the BP network produce a good agreement with the FEM calculations.

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SINGULAR STRESS IN PROXIMITY OF INTERFACE BETWEEN ANCHOR AND ROCK AND ITS ENDS

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2004, 23 (06): 946-946 doi:

[PDF] 319 KB (974)

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The effectiveness of prestressed anchors strongly depends on the level of combination of anchors and rock. Defects，which will affect the strength of the prestressed anchor reinforced slope, are inevitable on the interface between anchors and rock. There exist some misunderstandings on the distribution of stress fields in the proximity of the interface in design and computation analysis in the present literatures. A pullout model is set up in this paper and the fracture theory is employed to analyze the singular stress fields in the proximity of the interface ends. The results show that the shear and normal stresses are singular near the two interface ends (outer and inner), and the singular stresses may result in fracture damage there，so it is unreasonable for the equilibration stress method to ignore such damage. The results may directly be used to detect and control engineering construction，and can also provide instructions to the design of prestressed anchors of soil-rock slope.

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RESEARCH ON SHEAR MODEL OF RING JOINT BOLTS IN STAGGER-JOINTED SEGMENTAL LININGS

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2004, 23 (06): 952-952 doi:

[PDF] 323 KB (1161)

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A 3D finite element structural model is built in this paper to study the load-bearing behavior of stagger-jointed segmental linings of shield-tunnel and to analyze shear force transference between adjacent segmental rings. Based on the 3D analysis result, shear models of ring joint bolt is built and shear parameters between rings needed in 2D analysis with beam-spring model can be obtained by this shear model. The results of 2D analysis of shield-tunnel segmental linings have a good agreement with those by 3D finite element model. It shows that the presented shear model is effective for stimulation of shear force transference between adjacent segmental rings.

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TESTING STUDY ON WORKING PROPERTY OF SHIELD SEGMENT

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2004, 23 (06): 959-959 doi:

[PDF] 238 KB (1135)

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This paper analyzes the working properties of shield segment in different cases according to the field measurement results of the stress，deformation of rebars，and surrounding rock pressure in shield segment of a metro tunnel. The pressure，stress and moment are computed, analyzed and compared with designed results，and the rationality of design method is confirmed.

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WATER INRUSH PATTERNS AND THEORETIC CRITERIA
OF KARSTIC COLLAPSE COLUMNS

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2004, 23 (06): 964-964 doi:

[PDF] 305 KB (1080)

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Wherever the rock mass structures are located，groundwater always permeates through weak structure zones and may break through a key stratum and burst abruptly into working faces and form water inrush. It is shown by the theories and practice of water inrush prevention that the water inrush paths are generally in forms of ‘column pipelines’similar to karstic collapse columns of finite cross section area and different shapes，such as circular，ellipse，trapeziform，etc. Therefore，column pipelines of water inrush in coal mine areas can be imaged as‘thick wall canister’in terms of mechanics，the water inrush from roof and floor as‘lid failure of thick wall canister’，the water inrush from lateral walls of coal columns as‘lateral wall failure of the canister’，and hydraulic pressure and rock stress in the paths of water inrush as inner and outer pressures of the canister，respectively. Based on the imagination between column pipeline of water inrush and thick wall canister，the former can be generalized as column pipelines of uniform patterns，and simulated with mechanical models of thick wall canisters. When conditions of water inrush are analyzed with this model，shear failure theory in the structure analysis can be employed and mechanics analysis of models is reasonably simplified. The criteria of water inrush can be induced by a limit balance between the hydraulic pressure and shear of strata. The water inrush possibilities and locations can be effectively predicted and prevent in practice. It is indicated by an example of a very large water inrush volume on the 2171 working face，Fangezhuang mineral ltd.，that generalized water inrush patterns are correct， the models of thick wall canisters can be applied in practice and proposed criteria are correct and agree well with mining practice.

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FIELD SOIL-WATER CHARACTERISTICS AND ITS
ENGINEERING IMPLICATION

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2004, 23 (06): 969-969 doi:

[PDF] 289 KB (6278)

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In order to study soil-water characteristics of unsaturated soil slope, moisture probe and tensiometers are installed simultaneously for the soils at depths of 1, 2, 3 and 4 m at the crest of a cut slope in Hong Kong. Based on the field monitored results of volumetric water content and matric suction, field soil-water characteristic curves for the soils at different depths at the crest are determined. Compared with the obvious hysteresis of laboratory soil-water characteristic curves，the field soil-water characteristic curve shows negligible hysteresis. The negligible hysteresis may be attributed to the non-equilibrium effect during the heavy rainfall or the different measurements of volumetric water contents and matric suctions in the field and laboratory. Furthermore，the engineering implication of the field soil-water characteristic curve is also discussed in this paper.

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TESTING STUDY ON INTERNAL AND EXTERNAL FRICTION AND FRICTIONAL STRENGTH OF SOILS

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2004, 23 (06): 974-974 doi:

[PDF] 223 KB (1618)

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Friction mechanism and frictional strength of soils are analyzed in this paper. Through a series of experiments，the external friction between soils or between soil and concrete and the internal friction of soils are studied. The results show that (1) the primary factors influencing external friction of soils include the grain com- position of soils，the water content，the chemical properties of the pore water and the vertical load on soils，(2) the apparent and intrinsic internal friction factors reduce as the water content in soils increases，and the influence of the water content on the former is larger than that on the latter，(3) the suctions between grains (especially the variable structure suctions) in soils can exert a tremendous influence on the friction of soils，and (4) the influence of water content on external friction strength between structure surfaces is different from the influence on internal friction strength of soils. The distinguish between internal friction (factors) and external friction (factors) of soil is mainly that the formers belong to apparent ones，comprising the contribution of coherences such as generalized suctions that are relative to chemical character of aqueous solution and saturation state，and the latters belong to intrinsic ones，comprising the contribution of coherences such as generalized suctions of shear strength. The coherence and internal friction，which constitute the compressive strength of soil mass，are correlative.

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NUMERICAL ANALYSES OF PASSIVE EARTH PRESSURE
ON RIGID RETAINING WALL

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2004, 23 (06): 980-980 doi:

[PDF] 400 KB (1245)

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In this paper，numerical analyses for passive earth pressure problems of the rigid retaining wall are performed，aiming at improving understanding of the factors governing the magnitudes and distributions of the earth pressures on retaining walls. Passive earth pressure problems are analyzed by using a Mohr-Coulomb constitutive model of soil. A method to describe the frictional behavior between soil and walls is proposed using the elastoplastic joint elements. The computed variations of earth pressure with wall displacement in passive states explain well the influence of the wall friction and the wall movement.

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NUMERICAL ANALYSES OF ACTIVE EARTH PRESSURE
ON RIGID RETAINING WALL

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2004, 23 (06): 989-989 doi:

[PDF] 332 KB (1222)

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In this paper, numerical analyses for active earth pressure problems of rigid retaining wall are performed，aiming at improving understanding of the factors governing the magnitudes and distributions of the earth pressures on retaining wall. Active earth pressure problems are analyzed by using a Mohr-Coulomb constitutive model of soil. A method to describe the frictional behavior between soil and wall is proposed using the elastoplastic joint elements. The computed variations of earth pressure with wall displacement in active states explain well the influence of the wall friction and the wall movement.

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STUDY ON ACTION MECHANISM OF END BEARING PILES
AND ITS APPLICATION

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2004, 23 (06): 996-996 doi:

[PDF] 257 KB (1197)

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The interaction mechanism of pile and soil for end bearing type piles is studied. A new ground-pile system model, which considers the complicity of the system and the influence of sound bearing stratum under the pile tip on stress and displacement of multilayer soil around the pile, is established by using generalized elastic theory method and mirror imagine method. A theory is given for design and calculation of end bearing pile foundation. The optimization back analysis program that employs this theory can be applied to not only the calculation of the load-settlement curves，but also the analysis of the values of geo-parameters of multilayer soil around and under piles. The method and the program are validated with engineering cases.

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THICK PLATE ANALYSIS WITH APPLICATION TO PILE CAP DESIGN

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2004, 23 (06): 1001-1001 doi:

[PDF] 191 KB (7177)

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The thick plate is commonly used for the pile cap and the transfer plate, and a proper analysis of it can greatly affect the cost of the thick plate. In actual practice，soft support condition is sometimes adopted by engineers for modeling of thick plates. In this paper，the limitations of soft support in the determination of deflection and bending moment with very thick plates are studied. The distribution of superstructure loadings to pile caps and piles is also carefully investigated.

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ANALYTICAL METHOD OF INTERNAL FORCE AND DEFORMATION ABOUT BRACED STRUCTURE OF EXCAVATION BASED ON ELASTIC HALF-SPACE THEORY

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2004, 23 (06): 1007-1007 doi:

[PDF] 151 KB (1150)

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According to the Mindlin¢s solution in the elastic half-space under horizontal rectangular load，the relation between the lateral stress and the displacement of the braced structure is established. With the finite difference method, the internal force and deformation can be determined according the relation above.

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REAL TIME PREDICTION METHOD BASED ON GENETIC ALGORITHM
AND NEURAL NETWORK FOR DEFORMATION CAUSED BY DEEP EXCAVATION

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2004, 23 (06): 1010-1010 doi:

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Considering the basic characteristics of rock deformation caused by deep excavations, a real-time modeling predication method is established, based on genetic algorithm and neural network, in this paper. The predicted values agree well with the measured ones when this method is applied to the deep foundation pit project of the Liuwuzhou pumping station. The results indicate high prediction accuracy and the proposed method is a valid and useful tool for deformation prediction.

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PRACTICAL CALCULATION PROCEDURE OF
PILE-FOUNDATION SETTLEMENT

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2004, 23 (06): 1015-1015 doi:

[PDF] 287 KB (2189)

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The frictional force of pile under load action is calculated according to the proportional relation between the action of pile-side frictional force and pile displacement. Pile-foundation settlement is obtained by summing compressive deformation of pile stem and settlement of pile tip and multiplying the sum with the effective coefficient yq of pile group from the semi-empirical formula. The calculation procedure is simple, and the concept of calculation parameter is clear and easy to master. By the procedure it is convenient to calculate the settlement and verify the design.

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OPTIMUM DESIGN OF PRESTRESSED ANCHOR CABLES FOR BIII2 LANDSLIDE IN WATER SUPPLY RECONSTRUCTION PROJECT FROM DONGJIANG TO SHENZHEN

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2004, 23 (06): 1020-1020 doi:

[PDF] 314 KB (947)

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The fundamental features of the landslide BIII2 with expansive soil and soft rock，occurring in water supply reconstruction projection from Dongjiang to Shenzhen, is analyzed in this paper. Some important issues of reinforcing design with prestressed anchor cables are discussed. The bearing force characteristic of prestressed anchor cables and the stability of the slope are analyzed according to the considered issues. The key factors that influence the design parameter are identified based on analysis of factors with application of theory of optimization and decision. The optimum value of design parameter is determined by optimal decision of the key factors. The optimum design of reinforcing project with prestressed anchor cables is given based on the analysis of sliding surface and the strength data. Finally the stability analysis of the BIII2 landslide shows that the reinforcing project is feasible and have played an important role in timely treatment of the landslide.

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APPLICATION OF GEODRAIN-LOADING METHOD TO
RECLAMATION ENGINGEERING

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2004, 23 (06): 1025-1025 doi:

[PDF] 328 KB (1269)

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An engineering example is introduced，which applies prefabricated strip to treat the deep silt with dredger-reclaimed sand as load in Zhanjiang reclamation project. With careful monitoring, considering the accordance of the construction schedule and the loading speed, the reclaiming process is integrated with the treatment of soft soil in this case. The investment is therefore decreased and the term of works is shorten. The result of the long-term settlement observation shows that the degree of consolidation of the 13-meter-thick silt is above 80% at the end of the first two years, which indicates that the method can increase the consolidation speed.

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ANALYSIS AND SELECTION OF BUILDING PILE DESIGN
PARAMETER IN GUANGZHOU

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2004, 23 (06): 1032-1032 doi:

[PDF] 195 KB (1343)

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Some methods are put forward to evaluate ultimate flank friction and ultimate tip resistance of piles according to the geotechnical engineering condition in Guangzhou. The methods have been applied to design the engineering pile foundation in practice.

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DEFORMATION BEHAVIORS OF SOFT FOUNDATION
UNDER LARGE OIL TANK

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2004, 23 (06): 1037-1037 doi:

[PDF] 334 KB (1333)

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The deformation behaviors of oil tank foundation，which sits on deep-thick liquidated soft soil of the estuarial coastal area，are studied in this paper. The soft soil is treated with gravel piles, plastic drainage bands and water filling preload. Through the long-term monitoring of deformation of the deep soil and surface soil, a great number of primitive data were obtained. In this paper, the plane inclination and non-plane inclination of the surface and deep soil, and the sway settlement of the round wall are discussed. The settlement of the oil tank foundation is analyzed and evaluated. At last, the reasonable distance between tanks，the rational depth for the settlement calculation and empirical factors of the settlement are also presented.

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APPLICATION AND ANALYSIS OF SPARSE PILE SUPPORT FOR
DEEP FOUNDATION

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2004, 23 (06): 1044-1044 doi:

[PDF] 267 KB (1093)

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The soil arch theory is applied to the foundation support. The Huachengdadao metro station foundation is taken as the relevant example in this paper to explain the application. Based on the analysis of the geological conditions, the soil arch theory is adopted in the optimal design of the foundation，and the Lizheng deep foundation software is used to calculate the foundation displacement and stability. The results prove that the sparse pile support for deep foundation is stable and economical，and the support pattern is worth developing.

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ANAYLYSIS AND REMEDY OF PILES UNDER EMBANKMENT
ON SOFT SOIL FOUNDATION

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2004, 23 (06): 1049-1049 doi:

[PDF] 460 KB (1073)

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Embankment on soft soils, especially unsymmetrical embankment often leads to pile reflection or damage. In order to seek better ways to prevent such problems，an analysis method is presented based on the experience obtained from two of such projects，and some remedy methods are proposed to protect the piles from damage. The presented results may also be helpful to other projects in pile design and construction in hydraulic and civil engineerings.

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ACHIEVEMENT AND APPLICATION OF PILED RAFT FOUNDATIONS

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2004, 23 (06): 1054-1054 doi:

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The research achievements and application of piled raft foundations at home and abroad in recent years are summaried，and piled raft foundation is compared with conventional foundation in terms of economy. Some conclusions about main parameters and economic factor that influence the foundation design are presented.

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2004-06中文目录

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2004, 23 (06): 1081-1081 doi:

[PDF] 117 KB (664)

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