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2005, 24 (05): 0-0 doi:

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2005-05期目录

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CLAY MINERALS AND FAILURE OF SLOPES

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2005, 24 (05): 729-729 doi:

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As a microcrystalline material，the fine crystal and special structure of clay minerals make the aggregation-clay present several important properties，such as low permeability，high viscosity，high cation exchange capacity，dispersion-flocculation and so on. Many sedimentary rocks contain clay minerals and 76% of forming-rock minerals of slope rocks can produce clay minerals during the weathering processes. Clay minerals distribute extensively in various slopes made of sedimentary rock，weathering profiles of igneous rock，metamorphic rock and sedimentary rock and colluvial deposits. Because of clay minerals，lutites fail easily，and the sensitivity of their strength and deformability to change in water content is high. Secondary clay minerals in rock may bring about marked changes in strength and deformability of parent minerals，mineral aggregation and rock and promote rock to evolve toward loose medium. Macro discontinuities are the main forming and assembling places of clay minerals，and the illuviation of secondary clay minerals in fracture surface and the rock inside fracture surface will cause the strength of discontinuities and rock mass to decrease. Clay minerals are key components of slipping zones of landslides. Slipping zones have a lubrication effect between landslide masses and bedrock. The higher the content of clay minerals in slipping zones is，the more remarkable the lubrication effect is. Slipping zones may act as impervious boundaries and separate landslide masses from the surrounding media. Thus landslide masses are changed into independent hydrogeological units，and the ability of retaining infiltrated water and sensitivity of slope stability to raining processes are raised correspondingly. To sum up，clay minerals may accelerate time-dependent deformation of slopes，and their contribution to slope evolution and failure of slopes is notable.

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CATASTROPHIC MODEL AND TESTING STUDY ON FAILURE OF STATIC LOADING ROCK SYSTEM UNDER DYNAMIC LOADING

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2005, 24 (05): 741-741 doi:

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The stability and its changing law of uniaxial static loading rock system are analyzed by the catastrophe theory. The relationship between dynamic loading and the response of uniaxial static loading rock system is nonlinear and changing law of self-vibration frequency of the system is found out to be adherent to the nonlinear dynamics model of uniaxial static loading rock system. It is shown that when dynamic loading frequency and amplitude reach certain value，fierce jump of amplitude of uniaxial static loading rock system under dynamic loading will occur，then failure of rock specimen subsystem will appear. And the intensity of dynamic signal plays a decisive role in the evolution of uniaxial static loading rock system under dynamic loading. These theoretical analytical results are proved by experiment on uniaxial static loading rock system under dynamic loading.

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TESTING STUDY ON FAILURE MODE OF FILLED-SOIL SLOPE BEFORE AND AFTER RAINFALL

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2005, 24 (05): 747-747 doi:

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According to the principles of similar models，the failure characteristics of a tamped filled-soil slope under continual rainfall of 7 days and strong rainfall of 2 hours later are studied by indoor experiments in a large experiment box，and the result is compared with that without rainfall. The failure modes of the slope before and after rainfall are discussed. It is pointed out that the tamped filled-soil slope takes the combined failure mode of plane and convex camber before rainfall and takes the combined failure mode of plane and catenoid after rainfall，and both of them are complicated failure modes. So it is unreasonable to analyze the stability and design the support parameters with the arc failure mode.

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3D FINITE ELEMENT SIMULATION ON DEFORMATION OF SOIL MASS DURING SHIELD TUNNELING

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2005, 24 (05): 755-755 doi:

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Based on the comprehensive analysis on the primary components of ground movement associated with earth pressure balance(EPB) shield tunneling，a three-dimensional nonlinear finite element model for simulating EPB shield tunneling is proposed. The proposed numerical procedure can simulate the full excavation sequence and consider factors such as jack force behind the machine，earth pressure on tunneling face，excavation，advancing of shield，installation of lining，and backfill grouting. The proposed modeling techniques are applied to simulate a tunneling project in Shanghai. The distributions of soil displacement around the tunnel and on the ground surface associated with the shield tunneling operation are analyzed in detail. According to the comparisons of numerical results with field measurements，the proposed numerical procedure is found to be an effective approach for predicting the deformation due to EPB shield tunneling

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NONLINEAR RHEOLOGICAL MATHEMATICAL-MECHANICAL MODEL OF SURROUNDING ROCK DEFORMATION OF ROADWAYS OR TUNNELS AND ITS PRELIMINARY APPLICATION

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2005, 24 (05): 761-761 doi:

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A set of 3D rheological testing apparatus for surrounding rock of roadways or tunnels was developed by the authors，and rheological experiments and monitoring on it have been going on for over 10 years. Based on attenuation characteristics of long-term strength and strain energy conservation law of rock，a nonlinear rheological mathematical-mechanical model of rock is established，which differs form composite models of elastic，plastic or viscous elements. Based on this model，a nonlinear rheological mathematical-mechanical model of surrounding rock deformation of roadways or tunnels is established. Uniaxial compression strength can be converted to triaxial compression strength by linear Mohr strength theory，so uniaxial compression strength can be used to calculate 3D strain of surrounding rock of roadways or tunnels. The rheological values of surrounding rock deformation of roadways or tunnels calculated with the model are in good coincidence with the values obtained by experiments. The model is successfully applied to forecasting the width of loosened zone of a roadway.

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IDENTIFICATION OF RHEOLOGICAL CONSTITUTIVE RELATION OF ENGINEERING MATERIAL BASED ON OVERLAYER MODEL

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2005, 24 (05): 768-768 doi:

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The overlayer model is a powerful library of rheological models，and the procedure of determining the parameters of the overlayer model is also the procedure of identifying the constitutive relation. Based on this model，a novel approach of identifying the rheological constitutive relation of engineering material，is introduced to overcome the deficiency of the traditional identification procedure which relies too much on specific models. The nonlinear optimistic initial values of design variables are selected by analyzing the sensitivity of these variables with object function，then the deficiency of easily falling into local extreme point during the determination of parameters of rheological constitutive model is avoided effectively. A selection scheme of initial value in nonlinear displacement back-analysis(combined with the FEM and the complex optimization method) is also proposed.

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STUDY ON 3D VISUAL MODELING TECHNIQUE OF UNSTRATIFIED ROCK MASSES

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2005, 24 (05): 774-774 doi:

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Based on the work of Geotechnical Engineering Research Institute of CUMT(Beijing)，the engineering rock masses are divided into two types and four sub types by their characteristics for 3D modeling，that is，stratified non-inverse continuous rock masses，discontinuous(faulted) rock masses，inverse folded rock masses and unstratified rock masses(intrusive rock masses，extrusive rock masses). According to geometric characteristics and geological data of unstratified rock masses，the suitable spatial data model of unstratified rock masses is put forward by means of GIS visual technique and corresponding modeling method. 3D modeling method of unstratified rock masses is established，in which section method is adopted. 3D reconstruction of a set of planar contours is used to create the surface model of unstratified rock masses. The problem of reconstruction of a set of planar contours is then translated into the problem of structuring equivalent surface of body data. Visual modeling system based on the modeling technique is developed，and this system is verified in the example of unstratified rock mass modeling in Lingbao gold mine.

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COMPARATIVE STUDY ON FINITE ELEMENT METHOD，MESHLESS METHOD AND NATURAL ELEMENT METHOD

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2005, 24 (05): 780-780 doi:

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The fundamental difference between the finite element method(FEM) and the meshless method(MM) lies in the difference of the construction methods of the shape function. But the two kinds of shape functions both serve as a partition of unity. Integration of the weak form over the problem domain is needed when solving the partial differential equation using the Galerkin method. The newly presented quadrature method based on partition of unit provides a unified approach for the integration of the weak form in FEM and MM. MM is advantageous over the traditional FEM in the problems involved with the propagation of crack and large mesh deformation and so on. But the imposition of essential boundary condition and the treatment of discontinuous field variable and the derivative are somewhat troublesome，and the computation cost is large. The natural element method(NEM) is a newly appeared numerical method to solve the PDE. NEM assumes the characteristics of MM and the advantages of finite element method，so it is a most promising method.

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STUDY ON INFLUENCES OF PRIMARY KEY STRATUM ON SURFACE DYNAMIC SUBSIDENCE

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2005, 24 (05): 787-787 doi:

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Due to differences in formation time and mineral composition，rock strata contain numerous layers of different thickness and strength. Practical experiences have shown that one or several thick and strong strata have a dominant effect on the movements and subsidence of rock strata above the underground mining excavations. The key stratum is defined as the stratum that controls the movements of a part or all of the strata in the overburden. The former is called the subordinate key stratum，and the latter is called the primary key stratum. By means of comparative analysis on the field measurement data of stratum movement and the surface subsidence，numerical and physical simulation，the influences of the primary key stratum on surface dynamic subsidence are studied. The results prove that the primary key stratum in the overburden control the dynamic process of surface subsidence，the break of the primary key stratum will obviously augment the subsidence speed and the subsidence boundary，and the subsidence speed and the subsidence boundary will change periodically as the primary key stratum break periodically. Based on the key stratum theory in ground control，the basic principle in the design of mining under buildings should ensure that the primary key stratum would not break.

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STUDY ON ROCK MASS JOINT MEASUREMENT BASED ON DIGITAL PHOTOGRAMMETRY

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2005, 24 (05): 792-792 doi:

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Rock mass joints，a typical sort of structural planes，are widely distributed in the rock mass. So the measurement and investigation on rock mass joints are the foundation for rock mass classification and the determination of physical and mechanical parameters. However，the traditional in-situ investigation using manual measuring tools is inefficient and costly. The digital photogrammetry is applied into rock mass joint measurement to overcome these disadvantages in this paper. Based on principles of digital image processing and the characteristics of images of rock mass joints，an interpretation scheme for images of rock mass joints based on digital photogrammetry is put forward，which includes geometrical transform，image enhancement，intelligent recognition and shape analysis. Of these procedures，the intelligent recognition for rock mass joints is discussed in detail. The feasibility of the interpretation scheme is proved in a typical case of digital image processing of rock mass joints.

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RESEARCH ON SUPPORTING STRUCTURE SYSTEM OF
YUANLIANGSHAN RAILWAY TUNNEL UNDER HIGH WATER HEAD

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2005, 24 (05): 798-798 doi:

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It is usual to use Fourier spectrum analysis to process ground penetrating radar signal，but the effect is not always as good as expected. Complex signal analysis is a new method to process signal. It owns high precision and high distinguishing ability. It can distinguish weak signal in deep place and determine the abnormal place by using several parameters together. Complex signal analysis and Fourier spectrum analysis are compared in the processing of signals of the cases of solution cavities and a lake. It is shown that the former is better than the latter in that the pictures obtained by the former reflect the abnormal more distinctly and accurately. The boundary surface of mud silting of different time under the lake and the solution cavities are distinct after the processing of complex signal analysis.

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STUDY ON WAVEFORM ACOUSTIC EMISSION TECHNIQUE FOR MONITORING BREAKAGE IN CONCRETE MATERIALS

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2005, 24 (05): 801-801 doi:

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Based on results of the three-point-bending experiments on concrete materials，the relationship between the cumulative energy of acoustic emission and load is studied，and waveform acoustic emission signal of different destruction states is picked up. Spectrum analysis is carried out，the results of which are compared with those of parameter analysis. The comparison shows that waveform acoustic emission signal can be used to disclose the characteristics of the concrete materials under loading in real time.

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STUDY ON MECHANISM OF REINFORCING SIDES TO CONTROL FLOOR HEAVE OF EXTRACTION OPENING

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2005, 24 (05): 808-808 doi:

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The surrounding rock of roadway is a compound structure consisted of roof，floor and sides. The sides of extraction opening are the weak coal mass，which affect the stability of floor directly. Numerical simulation for influence of the strength of side coal on the floor heave is carried out，which shows that the higher the strength of sides coal is，the lower the degree of floor heave is. So the method of reinforcing sides to control floor heave of extraction opening is proposed in this paper. A practical case proves that the floor heave of deep extraction opening can be controlled to a certain degree by reinforcing sides of roadway.

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RESEARCH ON COUPLING LAWS BETWEEN EME AND STRESS FIELDS DURING DEFORMATION AND FRACTURE OF MINE TUNNEL EXCAVATION BY FLAC3D SIMULATION

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2005, 24 (05): 812-812 doi:

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First the distribution laws of stress fields in the course of mine tunnel excavation are simulated by means of FLAC3D software，and the stress value in each unit is obtained. Then according to the stress values and the coupling laws between electromagnetic emission(EME) strength and stress fields during the deformation and fracture of coal or rock，the changing laws of EME strength during mine tunnel excavation are studied. The results show that the changing rules of simulated stress are in accordance with that of the theoretical analysis and the practical strata stress，which shows that the FLAC3D method can appropriately simulate the changing law of stress field in the course of mine tunnel excavation. The simulated values by taking a large area as EME resources are only 3～8 percent larger than that by taking the stress concentration zone as EME resources，which show that EME signal received on the stress concentration zone reflects the deformation and fracture degree of coal or rock. The EME signal in head-on area along the direction of tunnel excavation increases constantly to the summit value and then falls down along with the computation time step. The EME strength in the same monitoring point increases gradually with the increasing computation time step. The increase of it slows down when it increase to a certain value. The changing of EME strength reflects the changing of internal stress after excavation. The practical measured results of EME strength have the same changing tendency as the simulated results，which also testify the feasibility of the coupling method between EME strength and stress.

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DYNAMIC RELIABILITY ANALYSIS ON RESISTANCE OF TUNNELS TO LONGITUDINAL NON-STATIONARY EARTHQUAKE

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2005, 24 (05): 818-818 doi:

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Under the condition of non-stationary stochastic earthquake motion process，the numerical models of seismic responses of submerged tunnels are utilized to study the non-stationary stochastic seismic responses and the dynamic reliability of resistance of tunnels to longitudinal earthquake. Based on the basic principles of finite element dynamical analysis，an analysis method of the longitudinal non-stationary stochastic seismic responses and the aseismic reliability of tunnels is studied，and the evaluation formulas are derived for these purposes by using the impulse-response function and the principles of Fourier transform and theories of random vibration. The Nanjing Changjiang Tunnel is used as an example to compute the root-mean-square responses，the longitudinal aseismic reliability under non-stationary random earthquake loads and the reliability of earthquake resistance of its joint.

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ACOUSTIC PARAMETERS OF LOW-POROSITY ROCK UNDER DRY AND SATURATED CONDITIONS

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2005, 24 (05): 823-823 doi:

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A testing study is presented on propagation characteristics of P wave and S wave in rock samples under dry and water-saturated conditions. The samples，including slate，biotite gneiss and granite gneiss，are all low-porosity rocks with water absorption of only 0.05%～0.2%. The acoustic parameters of rock samples under dry and water-saturated conditions are tested with ultrasonic method. Much useful information about the inner structure of these rock samples is learned from P wave and S wave. P wave velocity in water-saturated granite gneisses and biotite gneiss becomes a little higher than that of the dry ones only by 1.35%～1.97%，but becomes lower in water-saturated slates by less than 0.95%. S wave velocity in three types of rocks becomes a little higher than the that of dry ones by 0.22%～1.61%. The anisotropy of waves(P wave and S wave) velocity in slate and biotite gneiss is observed which is strengthened by water saturation，however，such phenomenon has not been found in granite gneiss. The dominant frequency of P waves becomes lower when rock samples get water-saturated，which means the high frequency part is filtered. All rock samples present obvious anisotropy of dominant frequency.

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TESTING STUDY ON SOLUTE TRANSPORT IN FRACTURED MEDIA

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2005, 24 (05): 829-829 doi:

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A testing system，designed by the authors，of solute transport in fractured media is introduced. With this testing system，solute transport experiments can be carried out in fractured media of different scales. Pressure，temperature and concentration sensors are installed in fractured media，which can directly measure solution concentration anywhere in natural fractures. So this testing system excels other similar devices worldwide. Solute transport experiments are carried out by the testing system with NaCl tracer solution，and hydrodynamic dispersion parameters of NaCl tracer transport are solved by analysis-optimization method.

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CHARACTERISTICS OF WAVE PROPAGATION AND VIBRATION FRACTAL IN FLOWING GRANULAR MEDIA

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2005, 24 (05): 835-835 doi:

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The vibration acceleration signals at initial stage and steady stage in flowing granular media are tested，and the propagation of wave in the flowing field is analyzed. The flowing granular media are taken as weak transverse isotropic media，and the phase velocity expressions of P wave，SH wave and SV wave are deduced accordingly. Their propagation characteristics in flowing granular media are analyzed. Compared to normal ore drawing，the eccentricity of ellipsoid，the viscosity resistance and inner friction among granules and shear intensity of granules are decreased，and the loosening coefficient of granules is increased in vibration ore drawing，so the granules have better fluidity. The motions of granules by vibration are irregular，complicated and stochastic，so it has fractal characteristics，which is analyzed and simulated.

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PHYSICAL MODELING RESEARCH ON RELAXATION REGION OF CONSEQUENT ROCK SLOPE INDUCED BY ROAD CUTTING

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2005, 24 (05): 840-840 doi:

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The stability of consequent rock slope is related to the intersecting angle between the strike directions of the cutting slope and strata，but the exact relation is always unknown in specific practical cases. The unstable rock mass on the bedrock with a high dip angle may be dug out. But it may be very expensive to dig all rock mass on the bedrock with medium and low dip angles. So the relaxation region of consequent rock slope is greatly concerned. According to the modeling tests，the method to determine relaxation region is explained. And the upper limit of intersecting angle between the strike directions of the cutting slope and strata is also obtained.

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DISSIPATED ENERGIES AND STABILITIES OF AXIAL AND LATERAL DEFORMATIONS OF ROCK SPECIMENS IN UNIAXIAL COMPRESSION

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2005, 24 (05): 846-846 doi:

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irstly，the dissipated energies induced by axial and lateral plastic deformations of rock specimens under uniaxial compression and the relation between them are analysed. Based on gradient-dependent plasticity in which the thickness of shear band is determined by characteristic length of rock，analytical solutions of dissipated energies in axial and lateral directions of rock specimens in uniaxial compression are derived，respectively. The presented theoretical results show that dissipated energy consumed by shear band is composed of two parts，axial and lateral dissipated energies. Dissipated energy due to axial plastic deformation is proportional to that of lateral plastic deformation and the proportional coefficient is dependent on inclination angle of shear band. According to the actual measured value of shear band inclination，the dissipated energy of axial plastic deformation is greater than that of lateral plastic deformation. As flow compressive stress approaches zero，the dissipated energy by shear band，the dissipated energies of axial and lateral plastic deformations attain their maxima. Bigger inclination angle of shear band leads to bigger dissipated energy of lateral plastic deformation and smaller dissipated energy of lateral plastic deformation. Secondly，shear instabilities of axial and lateral deformations of rock specimens in uniaxial compression are investigated. Shear stress between shear band and elastic rock outside the band is decomposed to horizontal and vertical shear stresses. Similarly，plastic shear deformation of shear band is divided into axial and lateral deformations. Relation between the horizontal shear stress and lateral plastic deformation and relation between the vertical shear stress and axial plastic deformation are presented，respectively. It is shown that the slope of horizontal shear stress-lateral plastic deformation curve is equal to that of vertical shear stress-axial plastic deformation curve. The two curves are dependent on the structural size，therefore，the slope cannot be taken as a constitutive parameter of rock materials. Based on theory of stiffness，instability criterions of specimens composed of shear band and elastic rock outside the band in the axial and lateral directions are proposed analytically. The two criterions are identical，which depend on constitutive relation of rock materials and structural size of rock specimens.

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DETERMINING PARAMETERS OF DAMAGE MODEL OF SOFT SOILS USING MERCURY INTRUSION POROSIMETRY

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2005, 24 (05): 854-854 doi:

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Based on analysis on deformation mechanism of structured clay，the mercury intrusion porosimetry is applied to study the change of pore size distribution during the loss of structure strength of soft soils. Pore structure breakage potential is defined in terms of the evolution of the pore size distribution in different stress level，damage variable is defined and damage evolution equation is proposed accordingly. Then the masonry model is used to develop a method which determines the parameters of damage model of soft soils by using the results of mercury intrusion porosimetry. The comparison between results of triaxial compression test and that of computation shows that the method is applicable.

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NEW PARAMETER TO DESCRIBE VISCOPLASTIC PROPERTY OF CLAY

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2005, 24 (05): 859-859 doi:

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In order to study the viscoplastic properties of clay，triaxial compression tests by using computer controlled triaxial apparatus with local displacement transducer(LDT)，and one dimensional compression tests were performed on undisturbed and reconstituted specimens of three types of Japanese Pleistocene clay(Kitan clay，Ohi-machi clay，and Fujinomori clay). In the tests，the axial (vertical) strain rate was changed stepwise many times，and drained creep tests were performed several times during monotonic loading at constant strain rate. Global unloading (and also reloading in some tests) was applied，during which creep loading tests were performed several times. Results of triaxial and uniaxial compression tests on the different types of Pleistocene clay are presented in this paper. The results show that viscoplastic properties of the clay are significant in all tests. Analyses on the results show that the stress change upon a step change in the strain rate is always proportional to the instantaneous stress in both triaxial and uniaxial compression tests. In order to describe the viscoplastic property of clay，a new parameter β，called viscoplastic parameter，is introduced，which can be obtained with traditional triaxial or uniaxial compression tests by changing the axial strain rate stepwise many times. The viscoplastic properties of a given clay specimen can represented by the b value. A larger b value means a larger viscosity. Test results also show that the β value is generally smaller with undisturbed clay than with reconstituted clay and in drained triaxial compression than in uniaxial compression.

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TESTING STUDY ON SATURATED LOESS LIQUEFACTION

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2005, 24 (05): 864-864 doi:

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Systematic laboratory tests on loess liquefaction are performed to study the testing methods，liquefaction mechanism，liquefaction criterion，influence factors and development of pore pressure and strain. Some laws and conclusions are obtained.

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WORKING PERFORMANCE OF PILES AND SOIL IN COMBINED-PILE COMPOSITE FOUNDATION

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2005, 24 (05): 872-872 doi:

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The performance of single-type-pile composite foundation and the concept of combined-pile composite foundation are analyzed. The vertical working performance of piles and soil of three-element and four-element composite foundation is compared and analyzed based on data form pressure cells，manometers and sensors under load distribution plate in loading tests. The influence factors of the performance are discussed. The results show that the four-element composite foundation is similar to the three-element composite foundation in the variation of the stress on the top of piles and soil with loading，but different from the three-element composite foundation in the variation of the load sharing ratio and the stress ratio with load，which is determined by the stress growth rate of piles and soil. Data from plate loading tests shows that the settlement of combined-pile composite foundation varies gradually with pressure. With the pressure increasing，the soil between inside piles reaches plasticity prior to piles，and piles bear the major part of load increment when the settlement reaches certain value. The combined-pile composite foundation should be designed according to settlement controlling. The pressure corresponding to the turning point or the point with maximal curvature in the curve of the inter-pile soil or secondary pile¢s load sharing ratio versus load obtained by plate loading test can be regarded as the characteristic value of bearing capacity of combined-pile composite foundation. When the plate area is not equal to the actual treatment range，the characteristic value of bearing capacity may be determined by the ratio of test value and calculation value with two kinds of size. It is pointed out that the performance of combined-pile composite foundation is influenced by the bond strength，length and replacement ratio of piles，the thickness and material of cushion，and the time.

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FORMULA OF RANKINE PASSIVE EARTH PRESSURE IN TRIAXIAL STATE OF STRESS

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2005, 24 (05): 880-880 doi:

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The traditional formula of Rankine passive earth pressure of retaining wall is deduced based on Mohr-Coulomb strength theory in which the intermediate principal stress is not considered. In this paper，the formula of Rankine passive earth pressure of retaining wall in triaxial state of stress is established based on twin shear strength theory. A calculation example shows that the passive earth pressure of retaining wall is increased when the influence of the intermediate principal stress is considered.

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STUDY ON ANTI-CONSOLIDATION AND REBOUND BEHAVIOR OF SOFT GROUND IMPROVED BY SURCHARGE PRELOADING AFTER UNLOADING

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2005, 24 (05): 883-883 doi:

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Based on a series of basal hypothesis on soft soil，a basic anti-consolidation equation of saturated soft ground is deduced under the condition of unloading，and the corresponding analytical solution under the condition of single-level constant-speed unloading is obtained. Then the mechanism of rebound deformation is analyzed，and the calculation formula of rebound deformation is provided. Based on the case history，the generation and dissipation process of the negative excess pore water pressure in the anti-consolidation zone of the ground improved by surcharge preloading are studied，and the development law of rebound is obtained，which explains the phenomena of the small rebound magnitude and fast stabilization after unloading.

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TESTING STUDY ON HPDE SPIRAL PIPE USED IN SOFT SOIL AREA OF SHANGHAI

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2005, 24 (05): 889-889 doi:

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HPDE (high-density polyethylene) spiral pipe has a broad application prospect for its unique properties. In a test on its application in soft soil area of Shanghai，the loading scheme simulates the load situation of practical projects. The mechanics-deformation patterns of HPDE spiral pipe and pipe-soil interaction mechanisms in various experimental stages are analyzed based on the test data and properties of soft soil in Shanghai，which offeres the theoretical basis for its application in engineering field. Some suggestions and technical requirements are provided for design and construction in Shanghai in aspects such as laying style，rational channel dimension，and thickness and density of backfill.

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IN-SITU TESTING STUDY ON RETAINING MISCELLANEOUS FILL SLOPE BY USING COMPOUND SOIL NAILING

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2005, 24 (05): 898-898 doi:

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In-situ testing study on the mechanical behavior of soil nailing and the displacement characteristics of miscellaneous fill slope is carried out. A number of significant conclusions are proposed. For the first time，double arciform strain of the soil nailing is observed in the miscellaneous fill. It is considered as the result that there are two (or more) potential slide planes in the miscellaneous fill. The critical anchorage length is analyzed and determined for the first，which is 9 m in this experiment. The ritical anchorage length is formed because of the transfer of the peak value point，the zero value point of the stain (stress) and the wreck point at the same time. It is found out that all anchorage structure (anchor-bolt，anchor-cable and soil nailing) have this characteristic.

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TESTING STUDY ON SETTLEMENT OF TREATED SOFT SOIL GROUND OF RAILWAY

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2005, 24 (05): 905-905 doi:

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Taking the results of the test on the treated soft ground of the Guangzhou—Zhuhai Quasi-High-Speed Railway for example，the settlement of the border piles beside the embankment toe，transverse and lengthways differential settlement of the surface，and the settlement caused by horizontal displacement are discussed. The method to determine the thickness of the compressed layer in calculating the settlement of soft ground is proposed. In the computation of settlement and stability of embankment，the additional load caused by settlement of embankment on the large-deformation soft soil ground which is deep and thick should be considered. For the railway embankment，the differential post-construction settlement induced by different ground treatment method need not to be considered. The results show that in the calculation of foundation settlement，the method of controlling strains and the method of controlling stresses should be used respectively，according to the specific positions of the foundation，to determine the thickness of the compressed layer.