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2005, 24 (04): -0 doi:
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2005-04期目录

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RANDOM-FUZZY MONOVARIANT LINEAR REGRESSION METHOD FOR DETERMINING THE SHEAR STRENGTH PARAMETERS OF ROCK

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2005, 24 (04): -547 doi:
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This random-fuzzy monovariant linear regression method for determining the shear strength parameters is modified in consideration of the randomness and fuzziness of rock. The formulae for calculating the uncertainty and variation coefficient of regression coefficients，and correlation coefficient of the regression equation，are derived. Based on the experimental data of triaxial compression test，methods for determining the values of the shear strength parameters of rock are discussed. The regression equation of the random-fuzzy monovariant linear regression method is more consistent with the experimental data than the least squares method. The results show that the proposed method is preferable to the conventional one.

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BACK ANALYSIS ON RHEOLOGICAL PARAMETERS BASED ON PATTERN-GENETIC-NEURAL NETWORK

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2005, 24 (04): -553 doi:
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An intelligent algorithm by which multiple rheological parameters of rock can be analyzed simultaneously is proposed. This method，namely the pattern-genetic-neural network algorithm (PGNNA)， naturally combines pattern search (PS)，genetic algorithm (GA)，and neural network (NN). The samples produced by uniform design are used to train NN whose architecture is determined in global optimization by pattern-genetic algorithm(PGA). NN that has optimal architecture and has been trained by optimal prediction algorithm is used to describe relationship between the rock rheological parameters and displacement. Rheological parameters are searched in global space by PGNNA，instead of a certain numerical calculation. This method improves the precision of back analysis on parameters，shorts the time of calculation，which is almost impossible for some traditional methods because of the long time of calculation. The practical engineering example shows feasibility and advantages of this method.

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STUDY ON p-VERSION ADAPTIVE BLOCK ELEMENT METHOD FOR ROCK MASSES

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2005, 24 (04): -559 doi:
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A p-version adaptive block element method for rock masses is presented to control the computational accuracy of block element method. According to current numerical solution of block element method，the contribution of higher-order shape function on each generalized node to the improvement of computational accuracy is evaluated by using the hierarchical characteristics of generalized stiffness matrix. Then，those useful generalized nodes are selected，and the generalized stiffness matrix is enlarged. A more accurate numerical solution can be obtained after the new equilibrium equations are solved. The adaptive processes are repeated until the results are accurate enough. The methodology proposed is proved to be valuable and efficient by a numerical example.

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CONSTITUTIVE MODEL OF STRUCTURAL LOESS

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2005, 24 (04): -565 doi:
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Natural sedimentary loess has structural properties，and it shows different mechanical properties before and after structural failure. Laboratory tests are performed to reveal the structural properties and collapsible deformation characteristics. The yield function and damage function of the unsaturated loess are established based on the principle of loess damage evaluation principle，the relationship between stable porous ratio and stable state of wholly-disturbed saturated clay，and the fact that inverse deformation is caused by the slip and crash among masses. The constitutive mathematical model of unsaturated natural loess is set up，by which loading process and other properties can be simulated. This model has clear physical meaning and the numerical calculation by it agrees well with tests.

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NUMERICAL SIMULATION OF FRACTURE PROPAGATION OF ANISOTROPIC ROCK-LIKE MATERIALS

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2005, 24 (04): -570 doi:
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The beam-particle model (BPM2) is used to model fracturing behavior of rocks. This numerical method used simulating damage and fragmentation phenomena of rock-like materials is presented on the basis of discrete element method (DEM) and lattice model. Random distribution of three types of beams in BPM2 is employed to simulate the spatial variation of mechanical parameters of brittle rock-like materials. The model of anisotropic media is generated automatically and used to investigate the mechanical behaviors of these low-porosity materials. The numerical simulation results of fracturing process in anisotropic brittle rock-like materials under uniaxial compression show that the initiation，propagation and linking of the fractures in the rock samples at mesoscale level produce the macro-failure of rock samples. The comparison with failure modes of pillars in underground mines proves this method is appropriate and efficient for simulating fracture propagation of anisotropic rock-like materials.

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3D VISUAL CONSTRUCTION OF COMPLEX ENGINEERING ROCK MASS STRUCTURE AND ITS APPLICATION

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2005, 24 (04): -575 doi:
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Structural analysis of rock masses by 3D visualization technique is the inevitable trend of engineering geologic research. Due to the complexity and irregularity of rock mass structure in large-scale projects，most traditional methods have some limitations on data quantity and analytic speed. Based on NURBS technique and some associated advanced theories，a new approach of 3D visual construction of rock mass structure is put forward. Then，with the measured discrete information and a series of deciphered 2D sections，the 3D visual model of rock mass is realized with guide of viewpoint of system and classification，and corresponding visual analysis，such as arbitrary cutting and digital drilling，on engineering rock mass structure can be performed based on the 3D visual model. It can give a more direct view of the interior structure of rock mass. Finally，the 3D model and visual analysis are applied to simulate rock mass structure in Nuozhadu hydropower station，and the results provide important references to the design.

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2005, 24 (04): -581 doi:
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The sunken topography was formed after opencast working was finished in Mujia Hill，and 375 000 m2 continuous and gently inclined abandoned stops were formed because of illegal mining. To prevent illegal mining and the potential danger of air shock wave resulted from sudden roof caving，it is proposed that the abandoned stope near 143 section in Mujia Hill be disposed by ore-pillar dilapidation. Caving angle and displacement angle can’t be determined by FEM for it is applicable to elastic and plastic medium. So the minimal uncontrolled roof-fall span，displacement angle and caving angle are studied by similarity simulation. The results show when the minimal roof span of 110 m is adopted，uncontrolled collapse of phosphorus dolomite roof and dolomite roof can be guaranteed，and surface subsidence and rock movement are not notable. If the big ore pillar of upside is entirely dilapidated，roof span will arrive at 140 m，caving angle of 78° and 65° will be caused，respectively，and displacement angle will arrive at 64.4°. Limit span determined by similarity simulation is between that by FEM and that by the formula proposed in the paper.

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FRACTAL FRAGMENTATION OF WEATHERED ROCK AND ITS APPLICATION IN ENGINEERING GEOLOGY

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2005, 24 (04): -587 doi:
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Statistical analysis on size distribution of mineral particle of weathered granite is carried out by using fractal method. The results show that the fracture process of weathering is a fractal one. The double logarithmic curves of particle number and particle size are folded lines，and each linear section in the curve corresponds to different fractal dimension. There are at least two fractal dimensions of the particle size distribution of weathered rock，one is the fractal dimension of crystallized mineral particles and the other is the fractal dimension of fractured particles. Based on the test result and theoretical analysis，it is pointed out that the accumulative frequency of particle size distribution has feature of exponential law. The formula for calculating the friable possibility of rock blocks by using exponential coefficient is also presented. Subsequently，the relationship among the shear strength，microstructure and fractal dimension is discussed. Based on the dimension reduction evolution of rock fracturing，the rate of weathering in term of fractal dimension is obtained.

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TESTING STUDY ON THE SWELLING MECHANICAL BEHAVIOR OF RED SANDSTONE

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2005, 24 (04): -596 doi:
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A series of tests are performed on rock rigidity servo testing system (MTS815.02) and rock odometer to study the swelling mechanical behaviors of red sandstone taken from the foundation pit of Hongshanyao Project (HSYP) in Nanjing. The interrelation of expansive force with water absorption rate and the law of expansive force with expansive strain are studied. It is concluded that the water absorption rate has a significant influence on expansive force.

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STUDY ON 3D FRACTAL DISTRIBUTION LAW OF THE SURFACE NUMBER IN ROCK MASS

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2005, 24 (04): -601 doi:
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Based on numerical simulation experiment，the fractal distribution law of surface number in rock mass is proved. According to large amount of calculate and theoretical inducement，the two important fractal parameters for fractured face are achieved. Through a great deal of calculation，the relationship between DS and 2D fractal dimension DL of trace is obtained，which is DL =DS －1，and DL is not related to the other parameters，including NS，dip angle ST，azimuth SP of 3D surface. The relationship of NS and the initial value of trace number NL is obtained. There are projection relation between NL and ST and SP，and proportional relation between NL and Ns which is NL = kNS，where k depends on surface projection. These relations provide the foundation for studying number and scale of surface in rock masses.

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RELIABILITY OF MULTIPURPOSE RESONANT COLUMN DEVICE IN TESTING RIGID SPECIMENS

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2005, 24 (04): -610 doi:
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he reliability of the multipurpose resonant column testing device，newly developed by the Institute of Engineering Mechanics，China Seismological Bureau，is investigated by testing the dynamic shear modulus of the rigid samples. In order to obtain the dynamic shear modulus of rigid samples，a revised coefficient method is presented by using several samples with known rigidities and then the revised curves of free-vibration and resonant-vibration are obtained. In the tests，the maximum error of ten tests of free-vibration and ten tests of resonant vibration on six kinds of steel specimens are all less than 4%. The correlation between curves of ten tests of free vibration on the steel specimens is good. By comparison of three fitting models for the revised coefficients，the best fitting formula for the revised curves is chosen. The free vibration and resonant vibration tests for three kinds of rigid samples with different known modulus are conducted，and the maximum error between the real values and the tested values obtained by the revised coefficient method is less than 10%. These results indicate that the revised coefficient method and curves presented in the paper are reliable and the new device is accurate and stable. So，the device can be used for testing the dynamic shear modulus of the rigid materials in small stain range.

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STATISTICAL DAMAGE CONSTITUTIVE MODEL FOR ROCK AND BACK ANALYSIS OF ITS PARAMETERS

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2005, 24 (04): -616 doi:
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Based on random distribution of interior defect in rock，a statistical damage constitutive model for rock is developed by using the continuous strength theory and statistical theory. Failure criterion of rock，as the distribution variable of the micro-unit strength in the constitutive model，greatly affects stress-strain curve and the equivalent elastic modulus of rock，and it must be chosen carefully for specific rock. By using back analysis method，the statistical distribution parameters in the constitutive model are solved. The proposed model can consider the effect of stress states and reflect the behavior in which the complete stress-strain curve of rock varies with stress-strain state. Comparison of the proposed model and experimental results shows that the proposed model is verified and can be applied in practical engineering.

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SEARCHING FOR SEEPAGE PATH OF 3D NETWORK IN FRACTURED ROCK MASSES

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2005, 24 (04): -622 doi:
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Fractures are the main seepage path in jointed rock masses，but fracture network system is so complex to describe that the description can only be released by the computer simulation technique. Using the 3D network computational simulation technique for random discontinuities，the distribution of fractures in space can be constructed，which provides the physics background of the porosity structure for the research on hydraulics problem of rock masses. The fractures relation pattern with corresponding algorithm is given on the basis of computational geometric，and then the graph theory is employed as the mathematical model to represent the mutual positional relation of fractures in 3D space. Utilizing a series of preprocessing operation such as defining the boundary condition，determining connected components，cutting the isolated fractures and dead ended fractures，the depth-first search algorithm for seepage paths of 3D network in fractured rock masses is implemented by computer automatically，and the feasibility is proved by an example of practical engineering application.

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RESEARCH ON FOUNDATION AND SECURITY OF THE EDIFICE IN JINKOU MUNICIPAL REFUSE LANDFILL

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2005, 24 (04): -628 doi:
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The aging process of Jinkou municipal refuse landfill in Wuhan city，China，is still in the unstable period，and it will greatly influence the foundation and security of the large-scale refuse transfer station which will be built on the landfill. Based on indoor geotechnical experiments，in-situ plate loading test and slope reverse analysis，the compressibility and the bearing capability and shearing strength of refuse soil are studied，and the refuse soil is defined as a kind of special loose cohesionless soft soil with organism and a great deal of fiber. The refuse soil is of high compressibility，uneven settlement characteristic，and high bearing capacity and shear strength. Foundation types for this case is discussed，the large-diameter bored pile foundation is chosen for the main part of project，and the raft foundation for annexes to deal with the problem of high and uneven foundation settlement. Based on the empirical formula，the negative friction caused by the settlement of landfill should be considered in the bearing capacity of piles. Based on chemical test and investigation in site，it is concluded that the refuse soil is of medium corrosively and the leachate is of intense corrosively to piles. Then，the three-level protective measures for reinforced concrete are put forward. There are plenty of pollutants of higher concentration in the leachate. After analysis on pollutant pathway to underground water in construction，major pollution-controlled measures are put forward，including whole-length steel tube timbering of bore，bentonite-mud protection of bore wall，and reduction of interval time between the ending of bore drilling and the beginning of concrete filling. Theoretic calculation shows that these measures are available to reduce the contaminated degree of underground water. There are plenty of poisonous gases in the landfill，and production of is still in the fastigium. The gases should be discharged before construction for long-term security of workmen and constructions，so a special cover layer is designed.

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STUDY ON DIFFERENTIATE CRITERIA OF EARTHQUAKE BREAKAGE OF FROZEN ROADBED

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2005, 24 (04): -638 doi:
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Based on the Mohr-Coulomb criteria and the direct addition principle of stress，the stress intensity criteria of earthquake breakage of frozen roadbed is proposed by introducing in two basic concepts of average normal stress and deviatoric stress，in which the coupling effect of dynamic shearing stress，dynamic normal stress of earthquake，and static normal stress and static shearing stress of soil self-gravity are considered. It is testified that the stress intensity criteria of earthquake breakage is reliable by a computation example of representative frozen roadbed section from Qinghai—Tibet railway in China.

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STUDY ON PERFORMANCE OF DOUBLE-LAYER LINING STRUCTURE AGAINST EXPLOSION-INDUCED COLLAPSE

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2005, 24 (04): -643 doi:
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The double-layer lining structure of soil aggregate backfilling layer and reinforced concrete structure is usually employed as anti-explosion-induced-collapse structure in the open-excavated underground civil defend projects. In the condition of the same explosion loading and the same total thickness of structures，the thicknesses of the soil aggregate backfilling layer and reinforced concrete structure are the major influencing factors of the performance of anti-explosion-induced-collapse structure. Field tests and theoretical analysis are carried out to determine the optimal structure thickness. The results show that the backfilling of low-resistance rock or soil materials has clear superiority in absorbing shock energy. The optimal thickness ratio and its application methods are given for several conditions.

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PREDICTING THE SURROUNDING DEFORMATIONS OF TUNNEL USING SUPPORT VECTOR MACHINE

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2005, 24 (04): -649 doi:
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The support vector machine is applied to predict the surrounding deformations of tunnel. Support vector machine is a new method of machine learning which is applicable to solve the nonlinear problem with small samples and high dimension. It is difficult to predict the surrounding deformations using the general method. The deformations of surrounding rockmasses are taken as a nonlinear deformation time series，then the deformations are preformed by using technique of time series analysis based on support vector machine. The nonlinear relationship among deformation time series is established，and the future deformations is predicted. The results show that this method is feasible and convenient.

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RESEARCH ON THE SELECTION OF SHEAR STRENGTH PARAMETERS OF SLOPE ROCKMASSES IN HUANGMAILING PHOSPHORITE MINE USING RANDOM-FUZZY METHOD

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2005, 24 (04): -653 doi:
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Based on the random and fuzzy characteristics of rockmasses，the random-fuzzy method and numerical characteristic formulae for the selection of shear strength parameters，c and j，are put forward. The case study of slope rockmasses in Huangmailing phosphorite mine show that the random-fuzzy method is better than traditional methods.

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SHEAR STRENGTH AND STRESS-STRAIN PROPERTIES OF ROCKFILL MATERIALS

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2005, 24 (04): -657 doi:
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In this paper，the results of large-dimension triaxial compression test of rock fill materials are analyzed，moreover，shear strength and stress-strain properties are studied. It is featured that the strength envelop of rock fill materials is nonlinear，and the stress-strain curve show a softening model or a slight hardening model. The Duncan-Chang¢s stress-strain model is modified for the case of rock fill materials and the variation laws of model parameters in test are discussed.

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THREE-DIMENSIONAL PLANAR MODEL FOR FLUID FLOW IN DISCRETE FRACTURE NETWORK OF ROCK MASSES

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2005, 24 (04): -662 doi:
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The discrete fracture network and fluid flow of an actual infiltration experiment performed in fractured rock masses are simulated with planar flow model. The fractures in the rock masses of the experiment are characterized through a mapped vertical shaft about 160 m2 and 7 television borehole of 8 m long. In the construction of the discrete fracture network model，an inverse method is used with the guiding principle that the observed fractures through outcrops and boreholes can be reproduced. With the inverse method，the complex error corrections associated with previous approaches in the statistics of observed fractures can be avoided. This is achieved by sampling simulated and measured fractures in the same way，and by fitting the simulated fractures to the observed ones. The mean and standard deviation of trace lengths，area density，and fracture frequency on boreholes of each fracture set are taken into account in fitting observed fractures. In the flow model，fractures are disc-shaped with a small thickness，and fluid flow takes place over whole the disc plane. The finite difference method is used in solving fluid flow problem，in which each fracture disc is automatically meshed into planar triangular elements，and 2D triangular grid in 3D space covering the entire fracture network is constructed. The transmissivity and hydraulic aperture of fractures of the test rock are estimated by fitting the observed discharge data. 30 fracture networks are generated，and the flow in each of them is analyzed to demonstrate the stability of the stochastic models of fracture networks and the flow. The mean discharge of the 30 fracture networks is very close to the observed.

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TESTING STUDY ON DEFORMATION CHARACTERISTICS OF SATURATED SAND UNDER REPEATED DEVIATORIC STRESS

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2005, 24 (04): -669 doi:
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Cyclic triaxial tests are conducted on saturated sand in drained condition with cyclic loading and unloading of deviatoric stress and constant spherical stress. The results of systematic test on deformation characteristics with respect to cyclic number in different dry density and consolidation stress condition are presented and analyzed. It shows that：(1) the volumetric strain takes different physical states，including three types of shear contraction (C1 type under initial loading，C2 type without dilation before unloading，and C3 with dilation before unloading)，dilation P and rigid shear R；(2) the relationship between volumetric strain and the deviatoric stress ratio q/p under every physical states are linear. Their parameters have a linear or exponential relationship with the initial volumetric strain of each physical state；(3) the volumetric strain process can be calculated by using the cyclic deviatoric stress and the above linear relationships of different physical states and the calculation result is consistent with that by experiment.

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IDENTIFICATION PROCEDURE FOR SHEAR STRENGTH PARAMETERS OF GEOTECHNICAL MATERIALS USING HYBRID GENETIC ALGORITHM

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2005, 24 (04): -676 doi:
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Rock slope stability depends on the strength features of the rocks. Determination of the strength of rock masses is difficult since the size of representative specimens is too large for laboratory testing. This difficulty can be overcome by using the parameter identification procedures. The inverse problem of geotechnical parameters identification is treated as the optimization problem. The hybrid genetic algorithm is presented and used for the identification of the shear strength parameters of geotechnical materials according to the observed shape of slip surface of rock slope. Genetic algorithm(GA) is a powerful alternative to traditional optimization methods which are too restrictive. One of the main advantages of GA is that it requires no information about the objective function. In order to identify parameters efficiently and in a robust manner，the gradient search method and genetic algorithm are combined to produce an adaptive procedure that has the merits of the two methods. The validity and efficiency of the proposed procedure are shown by an example involving parameter identification. The results obtained are compared with earlier results obtained by other methods.

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MODIFICATIONS TO GLOBAL STABILITY ANALYSIS ON SLOPE OF PILED FOUNDATION WHARF

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2005, 24 (04): -681 doi:
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A methodology is proposed for the global stability analysis on slope of piled foundation wharf，in which the interaction of piles and soil is considered，and some modifications to the existing design codes are presented. Genetic algorithm is employed in searching for the potential circular slip surface that has minimum safety factor. The circular slip surface is assumed and Bishop simplified method incorporating the stabilization effect of piles is adopted to calculate the safety factor of slope. An existing method based on the plasticity theory is used to determine the lateral forces acting on the pile section above the critical surface. The maximum stabilizing force of each pile is determined according to its embedded depth under different position of slip circle. In the presented methodology，the piles and slope can adopt different safety factors. By the calculations and comparisons on concerning engineering examples，the method is proved to be convenient，rapid and effective for the slope and pile system.

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MODEL TESTING STUDY AND CALCULATING ANALYSIS OF BEARING CAPACITY ON THE REINFORCED AEOLIAN SANDS GROUND

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2005, 24 (04): -687 doi:
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Because of the special physical and mechanical property of the aeolian sands in the desert，the aeolian sands is reinforced with the geogrids. Through the indoor model tests，the bearing capacity of reinforced aeolian sands with fifteen reinforcing plans and aeolian sands without reinforcement is studied. The bearing capacity，the deformation，and the stress of aeolian sands，are determined. On the basis of test results，the variation of bearing capacity of ground of reinforced aeolian sands is analyzed with different reinforcing plans and various intensities. Two-layer geogrids is recommended as the effective reinforcing plan，ground reinforced with reinforcement has bearing capacity 1.2 times higher than that of without reinforcement. Moreover，the strength mechanism and damaging pattern of reinforced aeolian sands are put forward. Finally，the calculation formulas of bearing capacity of ground of aeolian sands reinforced one-layer geogrids without bearing depth are established. The formulas are proved by the test results.

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OPTIMAL DESIGN AND APPLICATION OF SUPPORTING SYSTEM IN DEEP FOUNDATION PIT OF CHAOZHOU HYDRO-JUNCTION

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2005, 24 (04): -692 doi:
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The deep foundation pit of Chaozhou hydro-junction is located at the river bed. The construction sequences are very complicated as a result of its large excavation depth，unfavorable engineering geologic condition，great difficulty of construction and tight time requirement. All these factors are considered in the optimal design and application of supporting system of diaphragm wall with reinforced concrete strut in the deep foundation pit. Excavation scheme is determined accordingly，which can satisfy the requirement of operation of large machines，reduce the construction cost and ensure the construction schedule. The date from monitoring is consistent with the design.

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TESTING STUDY ON INTERNAL FORCES FOR PRESTRESSED ANCHOR CABLE FRAME IN REINFORCED SOIL SLOPE

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2005, 24 (04): -697 doi:
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Based on the field test，the distribution law of internal forces of prestressed anchor cable frame used in soil slope is studied. The law of internal forces under the same grade of anchor forces，the change of internal forces under the various grades of anchor forces，and the distribution of anchor forces in horizontal beams and vertical beams of frame，are proposed. The results show that the maximum positive moment appears at anchoring spot，and the minimum negative moment appears at the middle of the beam. In addition，due to the increase of anchor forces，the moment is linearly increasing. The calculation of internal forces for prestressed anchor cable frame is validated.

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SLOPE RISK ANALYSIS UNDER THE EARTHQUAKE EFFECT

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2005, 24 (04): -703 doi:
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Horizontal earthquake acceleration is used for slope risk analysis，and the relationship between the dynamical safety factors and corresponding static safety factors is obtained. The reliability of slope is expressed with the safety factor. The mathematic formulation of the slope failure probability is deduced with stochastic earthquake acceleration. In the case of a slope in the south-north water transfer project(SNWTP)，calculation results show that safety factor with the stochastic earthquake is 25% smaller than that without earthquake. It is clear that the influence of the earthquake is notable.

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STUDY ON UNLOADING EFFECT AND WIDTH OF UNLOADING ZONES IN EXCAVATING OF SOIL-LIKE MATERIAL SLOPES

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2005, 24 (04): -708 doi:
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The occurring mechanism of unloading crannies during excavating soil-like material slopes is analyzed. It is shown that the excavation changes stress in the soil or rock masses，and during the excavation，an extra lateral stress in the direction to the slope surface will act on the slopes. The generation of new crannies and the splaying of existing crannies are attributed to the extra stress. The characteristics of unloading crannies and the influencing factors of their displacements are summarized through centrifugal tests in test chamber about the excavation in silt，clay，and completely weathered mudstone. From the tests，it is concluded that deformations of the existing crannies will increase with the accretion of its obliquity，depth and approaching to unloaded surface. The relations of stretch and obliquity of cranny，deformation modulus and angle to unloading direction of cranny are put forward The method of determining the width of unloading zones is presented for practical engineering projects，and feasibility of the method is proved through an application in the bank of Yangtze River in Chongqing City.

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DAMAGE EFFECT OF THIN CONCRETE SLABS SUBJECTED TO PROJECTILE IMPACT

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2005, 24 (04): -713 doi:
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Perforation damage effects of thin concrete slabs produced by impact of projectile at high velocity are studied. Model test，numerical simulation，and dimension theory are employed to analyze the damage effects and the results of the three methods are well consistent. Empirical formula is derived to calculate residual velocity of projectile perforating through the thin concrete slabs. The macroscopic damage image of reinforced concrete slabs under impact effect are obtained through model test，and the residual velocity of the projectile are gained from the tests. Three-dimensional nonlinear dynamic finite element program and the brittleness damage model of concrete are introduced. The numerical simulation of damage process of experimental target slabs is accomplished. The physical processes such as penetration perforation and impact perforation of reinforced concrete slabs subjected to projectile with high speed are displayed visually. The simulation results fit well with the experimental damage image. Through dimension analysis，the dimensionless relationship between all parameters that influence the impact damage effect of reinforced concrete slabs are achieved. Regressive analysis of test data are carried out to obtain the calculation formulae for projectile residual velocities under the condition of penetration perforation or impact perforation.

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ANALYSIS ON SOIL-NAILED RETAINING STRUCTURE USING ENERGY METHOD

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2005, 24 (04): -721 doi:
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Soil nailing is a widely used means for slope stabilization in the last two decades. The traditional limit equilibrium method in the design of soil-nailed systems can not give the maximum depth Hu for soil-nailed retaining structure and excavation depth Dhi of each step. Based on energy method and power equilibrium equation，the formula of limit excavation depth of soil-nailed retaining structure is presented，and a new safety factor ki of each step and Dhi of each step are also established. Pseudo cohesion DC is obtained by taking the effect of reinforcement and restriction soil nail as the increasing soil cohesion. The main influence factors of soils and soil nails and the variation rules of limit excavation are analyzed. All these can be used for references to the design of soil-nailed retaining structures.