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2004, 23 (08): -0 doi:
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RHEOLOGICAL PROPERTY OF SOFT ROCK UNDER MULTIAXIAL COMPRESSION AND ITS EFFECT ON DESIGN OF ARCH DAM

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2004, 23 (08): -1237 doi:
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A nonlinear model and multiaxial rheological experiment results of soft rock are applied to practice，and the simulation agrees well with the reality. The deformation modulus decreases evidently and the nonlinear rheological property is more significant when the rock is immersed，which will affect the stress distribution of arch dams. In addition，it is found that the rheology of soft rock decreases with lateral pressure，so that the stress state of arch dam is improved.

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STUDY ON RHEOLOGICAL TEST AND VISCOELASTICAL CONSTITUTIVE MODEL FOR SHALE

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2004, 23 (08): -1242 doi:
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The shale deformation of a given dam is the main issue of the study on underground openings and high slope，so it is important to discuss the viscoelastical constitutive model of the shale. Three drill cores of the shale are selected to make simple beams for rheological test. Ten measuring points are chosen and strain gage is fixed on each point. Concentrated load acts on the center of the beam，and corresponding time-dependent strains of the ten strain gages are measured by using strain gauge. According to the mensurated strains，the viscoelastical constitutive model of the shale is obtained by inversion and analysis shows that the model accords well with the real viscoelastical behavior of the shale.

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REMOTE SENSING-ROCK MECHANICS(Ⅵ)——
FEATURES OF ROCK FRICTION-SLIDING AND ANALYSIS ON ITS INFLUENCE FACTORS

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2004, 23 (08): -1247 doi:
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The rock friction-sliding features in condition of bi-axial loading are experimentally studied with gabbro and granodiorite as examples. The five important influence factors，that is，normal stress，rock property，roughness of the friction surface，aqueousness and sliding rate，are experimentally studied and analyzed. It is revealed that (1) the higher the normal stress is，the easier the stick-slip is and the longer the period is between two consecutive stick-slippings，(2) if the boundary conditions are the same，stick-slip potentiality of gabbro is bigger than that of granodiorite，(3) the roughness of the friction surface has much influence on the stick-slip property，and the repeated frictions will increase the instability of stick-slip，(4) the friction strength of aqueous rock is to decrease，but it will recover gradually with the heat production and the water evaporation in the process of friction-sliding，and (5) in condition of low friction rate，the rock friction-sliding is chiefly stick-slip，while in condition of high friction rate，the rock friction-sliding is chiefly stable slip.

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STUDY ON BEHAVIOR OF STRESS-STRAIN FOR FROZEN SOILS SUBJECTED TO K0 CONSOLIDATION BY UNLOADING TRIAXIAL SHEAR TESTS

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2004, 23 (08): -1252 doi:
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In order to determine the behaviour of stress-strain of frozen soil in the deep alluvium，the triaxial unloading shear tests at temperature of －2 ℃，－5 ℃，－7 ℃，－10 ℃ and a confining pressure of 1～5 MPa were performed in cold laboratory after specimen experienced K0 consolidation. The testig results indicate that the radial unloading stress-strain curves can be divided into three different stages，that is，elastic stage，strain-hardening stage and the yield stage or flow stage. There is no displacement at a lower negative temperature and somewhat higher initial confining pressure，even if the confining pressure is removed to zero. The failure strength increases with the initial confining pressure increasing and the temperature decreasing. From the stress-strain equation of tested frozen soil，the ultimate principal stress difference (s1－s3)ult and the initial tangent modulus Ei can be obtained. The initial tangent modulus Ei does not depend on the initial confining pressure and is close to a constant at a state of lower negative temperature and higher initial confining pressure. The ultimate principal stress difference (s1－s3)ult increases linearly with increment of initial confining pressure and the role of temperature is not obvious at lower initial confining pressure. However，with the confining pressure increasing，it becomes pronounced gradually.

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FEM ANALYSIS ON TUNNELING AND WORKING OF WANJIAZHAI WATER TRANSMISSION TUNNEL

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2004, 23 (08): -1257 doi:
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A nonlinear stress and strain analysis of tunneling and working condition of No. 7 tunnel of Wanjiazhai water transmission project in Shanxi Province is conducted. The initial stress field is simulated by grading landfill，and the theory of unloading proposed by Duncan and boundary stress of elasticity were used to simulate excavation of the tunnel. Goodman joint elements are utilized to simulate the joints of liners. Both loading and unloading tests are conducted for determination of parameters of Duncan-Chang’s model. The loading on the pipes is evaluated according to Terzaghi’s theory on loosening earth pressure. Several working cases are analyzed and some reasonable results are obtained.

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ANALYSIS AND NUMERICAL SIMULATION ON STABILITY OF NEW SAFE-CLEANING BERM IN MINING WITH STEEP WORKING SLOPE

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2004, 23 (08): -1263 doi:
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Based on the study of slope mode of slightly declined granular structure in Xingqiao，a new mode of safe-cleaning berm is designed for mining with steep working slope. The dint cut and retaining wall are made by using of semi-steep slope. With safety and reliability，the new mode sustains steep slope mining，increases the angle of ultimate slope，and reduces 3%～5% of noneffective overburden amount. In order to analyze and validate the reliability of retaining wall，static loading calculation，ANSYS simulation of impact loading and in-situ test are made. By the calculation of static loading，the berm can withstand the granular extrusion without gliding and capsizing. ANSYS simulation shows that impacting destroy develops gradually. When the sliding masses come from the height of 10 times of the width of the sublevel，the retaining wall will collapse. During the two years of in-situ testing，the new mode of structure keeps safe successfully from coast impact. According to the above results，building a new safe-cleaning berm in 1～5 sublevels is economic measure that can meet the demand of safety.

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FULLY COUPLING ANALYSIS OF SEEPAGE AND STRESS FOR DEEP FOUNDATION PIT BASED ON DISPLACEMENT BACK ANALYSIS

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2004, 23 (08): -1269 doi:
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Based on Biot¢s consolidation theory，the fully coupling model of seepage and stress is established considering nonlinear coupling response of permeability coefficient. Applying the observed deformation data of deep foundation pit and surrounding soil during the early days of water discharge and excavation，optimal values of model parameters k，n，G and l are obtained with displacement back analysis. Seepage and stress of surrounding soil are simulated to predict deformation with the fully coupling model with and without considering coupling response of permeability coefficient，respectively. The analysis results are compared with observed data and it is showed that the calculated results with the model considering coupling response of permeability coefficient are closer to observed value than those results with the other model. So，the model considering fully coupling response of permeability coefficient is reliable and applicable.

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HYDRO-MECHANICAL COUPLING ANALYSIS ON STABILITY OF COFFERDAM OF TAI¢AN PUMPED-STORAGE STATION

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2004, 23 (08): -1275 doi:
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Based on the general principle of 3D hydro-mechanical coupling of finite differential equation，FLAC3D is applied to analyze the 3D saturation-unsaturation flow for the hydro-mechanical coupling of the embankment of Tai¢an Pumped-storage Station. At the same time，the effect of foundation excavation on the stability of embankment and slope of the foundation is studied. Computational result indicates that the core wall is very good for preventing seepage and enhancing the stability of the embankment and slope of foundation. The effect of excavating process on the stability of embankment and slope of the foundation is only local. Nearly no serious breakage of embankment and foundation occurs，and the designed width of the flat roof is rational.

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COUPLING ANALYSIS OF SEEPAGE AND STRESS FIELDS IN XIETAN LANPSLIDE IN THREE GORGES REGION

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2004, 23 (08): -1280 doi:
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The Xietan landslide body can be regarded as an interbedded structure with three permeable layers (slope wash，landslide deposit deposit，and effected zone of the landslide) and two relatively impermeable layers (sliding zone and foundation rock)，so it is important to consider the coupling action of seepage and stress in the slide to evaluate the stability of landslide. The coupled seepage and stress fields in the Xietan landslide are analyzed by means of the continuum model when the reservoir water level reaches elevation of 175 m. The hydraulic head distribution in the landslide，the uplift pressure distribution along the bottom of sliding zone and the distribution of stress components are obtained based on the analysis. The results show that the interbedded structure is adverse to the stability of the Xietan slide，and the coupling action has more important effect on the stress field than on the seepage field.

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SIMULATION ON SEEPAGE FIELD OF UNDERGROUND WATER IN YANKA DANGER SECTION OF JINGJIANG GREAT EMBANKMENT

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2004, 23 (08): -1285 doi:
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The Yanka section of the Jingjiang Great Embankment on the north bank of the Yangtze River is one of the zones with piping hazard in flooding seasons. Seepage fields of ground water at different river water levels are simulated by using the software of Visual Modflow developed by US geological survey. Different treatment models，such as models of presence of scuttle，seepage-proof walls，pressure-reducing wells and chaning the seepage coefficiency of artificial filling，are studied at high water levels. The results show that (1) a decrease in seepage coefficiency of artificial filling will reduce the seepage damage significantly in the high water level，(2) reducing of pressure wells has significant effect on preventing piping if ponds or scuttles are present，and (3) seepage-proof walls are effective against seepage damage if the walls reach the clay layer in the middle (about 20m in depth).

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ELASTO-PLASTIC ANALYTICAL SOLUTION OF DEEP-BURIED CIRCLE TUNNEL CONSIDERING FLUID FLOW FIELD

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2004, 23 (08): -1291 doi:
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It is assumed that all the influence factors surrounding deep-buried circle tunnel are axially symmetrical. Firstly，the solution of fluid flow field is resolved. Secondly，analytical formulae of elastic stress and displacement are obtained considering the body force of seepage. Thirdly，applying Mohr-Coulomb yield criterion，analytical formulae of plastic stress and plastic radius are obtained. An example is analyzed and contrasted with and without considering fluid flow field. The research shows that the influence of seepage field on stress field is intensive along with the gradient increment of inner and outer water head of tunnel，and the influence degree on tangent stress is more than that on radial stress. The distribution law of stress is not coincide with and without considering fluid flow. The compressive stresses and plastic radius are gradually decreased along with the increasing inner head，and the plastic radius may be zero if the inner head increases continually to some extent. The influence with considering influence of fluid flow is larger than that without considering the influence.

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NUMERICAL ANALYSIS ON LINING STRUCTURE OF RESTRICTED CYLINDRIC SURGE CHAMBER IN ROCK MASSES WITH STEEP OBLIQUITY

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2004, 23 (08): -1296 doi:
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The stability of lining structure of Langyashan restricted cylinder surge chamber in the rock masses with steep obliquity is analysed by using three-dimensional nonlinear FEM. The analytical method of surge chamber’s lining and surrounding rock stressed jointly is presented，and the computing formulae and methods of crack width and reinforcement rate are alse given. By computing for various schemes，the force-bearing state of the lining structure of cylinder surge chamber with bifurcation is illustrated，and a better numerical analysis method for similar cases is presented.

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RESEARCH ON COMBINED MOTION CHARACTERISTICS OF OVERLYING ROCK STRATUM AND POSITION OF KEY STRATUM

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2004, 23 (08): -1301 doi:
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[PDF 281 KB] (976)

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The combined motion of the overlying rock stratum of coal mine is regarded as a motion of the compound key stratum sustained by stiff rock stratum. The stress of the compound key stratum is discussed by using the elastic thin plate theory and the laminated plate theory of the compound material mechanics. The collapsing load of the key stratum is obtained by adopting the plastical limit analysis method structure. Based on the collapsing load，the posotion of key stratum can be estimated approximatively.

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VARIATION LAW OF QUANITY OF COAL DUST IN DRILL HOLE AND ITS APPLICATION TO DETERMINATION OF REASONABLE WIDTH OF
COAL PILLARS

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2004, 23 (08): -1307 doi:
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The relationship between variation law of quanity of coal dust in drill hole and distribution of abutment pressure is researched，and it is demonstrated that the distribution regulation of abutment pressure and support time of mining face can be calculated according to the quanity of coal dust in drill hole. Accordingly，the distribution of abutment pressure on the block coal pillar is measured at working face with a steeply inclined seam of the12010 face，NO.13 coalmine of Pingtingshan Coal Mine Group，which provides a basic data for persevering reasonable width of coal pillar.

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ANALYSIS OF BRITTLE DYNAMIC DAMAGE IN DAM AND ROCK FOUNDATION DUE TO EARTHQUAKE

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2004, 23 (08): -1311 doi:
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In this paper，a brittle damage-failure mechanism for rock structures subject to earthquake loading is adopted for analysis of dynamic responses of damaged concrete gravity dams and rock foundation. The concept of the modified net effective stress which involves the coupling affects among damage，pore pressure and porosity evolution in cracked rock mass and concrete is introduced into the modified Mohr-Coulomb failure criterion in order to express the brittle dynamic damage growth and propagation phenomenon. The developed brittle dynamic damage model is based on the localization of damaged failure in brittle materials. Therefore，the brittle dynamic damage process is considered as the process of local fractures in material without plastic deformations. The dissipations of energy during the dynamic process consist of dissipations of the local damage development，the local changes of seepage flow velocity and the local evolution of porosity within the networks of crack-damaged porosity only; no energy is dissipated with the everlasting deformation. The numerical results of the brittle dynamic damage analysis for the concrete dam and the rock foundation show that the significant damage growth starts in the upstream side at the corner between the dam and rock foundation where a high stress concentration area exists. Damage growth is found to be more susceptible in the softer rock foundation than that in the intact rock foundation.

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FINITE ELEMENT ANALYSIS ON SLOPE STABILITY OF EARTH-ROCK DAM UNDER EARTHQUAKE

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2004, 23 (08): -1318 doi:
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The problem of slope stability under earthquake is not yet solved because of complexity and nonlinear properties of soil and rock. The earthquake ground motion is of the stochastic nature，and the failure of earth rock dam under earthquake greatly depends on the details of ground motion. Based on definite stochastic seismic response and time-history seismic response analysis，the slope stability of earth-rock dam is studied by finite element method combining with Hook-Jevees searching method. First，based on time-history response analysis of a sand dam model excited by sine wave，the time-history of the limit sliding surface and the minimum safety coefficient of slope are obtained. Then，with input of equivalent power spectrum of the sine wave，the dam model is analyzed with the definite stochastic seismic response method，and the properties of slope stability and the location of sliding surface are determined. The results of the two analyses agree well with those of the dam model test. It can be concluded that the location and the stability of sliding surface are effected by the factors，such as the maximum value of acceleration，the predominant periods and the types of earthquake records. It should be noted that，the location of limit sliding surface of the dam model excited by sine wave is different from that of earth-rock dam under earthquake.

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MECHANISM STUDY OF BLAST-INDUCED INFLUENCE ON
VICINAL CURTAIN GROUTING

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2004, 23 (08): -1325 doi:
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The vibration induced by blasting in the vicinity of a dam foundation can induce some adverse effect on the curtain grouting. The peak particle velocity(PPV) caused by blasting is always adopted as the criterion in control of the blasting influence and few theoretical study has ever been carried out on this problem. The theory of stress wave is adopted in this paper to analyze the interaction between blast-induced stress wave and curtain grouting. The safe PPV in the vicinity of the curtain grouting is then theoretically derived by analyzing the breakage of the bound between curtain grouting and rock.

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STUDY ON RESPONSE SPECTRUM CHARACTERISTICS OF EARTHQUAKE ACCELERATION FOR ROADBED ON
PERMAFROST SITE

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2004, 23 (08): -1330 doi:
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At present，the aseismic problem of roadbed and other relevant earth structure on permafrost site has become a key problem that is not studied sufficiently in the past and needs to be solved urgently. Based on several typical cases of roadbeds of Qinghai-Tibet Railway Project，the response spectrum characteristics of earthquake acceleration for roadbed on permafrost site are studied by using two-dimensional dynamic FEM. The high-frequency El Centro wave and low-frequency Tianjin wave are input as an excitation. The result indicates that whether there is frozen layer，earthquake acceleration response spectrum is mostly the type of high frequency impulse，and the soil failure is bump type. In the mid and low frequency stage，the values of earthquake acceleration response spectrum for roadbed with frozen soil are larger than that without frozen soil when input is El Centro wave. But for Tianjin wave，there is no significant difference. Compared to different topography conditions，the frequence of input earthquake wave has great influence on earthquake acceleration response spectrum of roadbed. Especially，the existence of thawed basin ground enhances the effect of earthquake acceleration response for roadbed.

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赵芹1 何江达2 梁照江2

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2004, 23 (08): -1336 doi:
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The favorable influence of friction resistance，caused by the deformation of the concrete plug，is generally ignored in the design of plug for diversion tunnel，which makes the length of the plug over-conservative. In accordance with the working mechanism of plug，the formula of resistance is deduced. Then a real project case is taken to verify that the safety factor can be improved and the design length of plug can be decreased considering the resistance under some conditions，such shortening the construction period and reducing investment.

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STUDY OF SEEPAGE IN LOW-DIP BEDDED STRUCTURE OF XIAOLANGDI DAM ABUTMENT BY TRACER METHOD

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2004, 23 (08): -1339 doi:
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The bedded structure of the left abutment of the Xiaolangdi Reservoir Dam on Yellow River has a low dip and the quantity of seepage into the 30# drainage gallery is quite large even with grouting curtain. The permeability of the bedded structure is analyzed and the modern tracer theory and analysis method are applied to get the result of seepage，which shows that the seepage pathway to the 30# drainage gallery is quite different. The seepage from the drainage boreholes at the north side of the gallery is very large，and the seepage penetrates the impervious layer through bed-cutting fissures，flows into the permeable layer and finally reaches the drainage bore holes. According to water connection tests between boreholes，it is confirmed that flow in the fissure network has formed a concentrated seepage pathway. The water inflow from other drainage bore holes is relatively small. It is recommended to apply this modern tracer theory and method to solve complex seepage and leakage problems in the key hydraulic projects.

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STUDY ON EFFECT OF IN-SITU STRESSES ON PLASTIC REGION INDUCED BY EXCAVATIONS OF UNDERGROUND OPENINGS

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2004, 23 (08): -1344 doi:
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IN-SITU STRESS MEASUREMENT OF FANGSHAN GRANITE

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2004, 23 (08): -1349 doi:
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A borehole was drilled in granodiorite rockmass at Fangshan，Beijing. The depth of the borehole is 301 m with diameter of 110 mm. From about 30～301 m，all cores were oriented by cement end cap method. AE Kaiser effect tests on oriented core at depth of 270 m and 294 m were carried out. In horizontal plane，the orientation of larger horizontal principal stress is about the NS. Comparison of the result of AE Kaiser effect tests with that of hydrofracturing shows that they are consistent fundamentally on the whole.

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SOLUTION OF NONLINEAR CONSOLIDATION PROBLEM BY RADIAL POINT INTERPOLATION METHOD WITH UNEQUAL-RANK
POLYNOMIAL BASIS

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2004, 23 (08): -1353 doi:
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The famous Duncan-Chang model is adopted to make nonlinear numerical analysis on Biot’s consolidation problem by a new type of meshless method，the radial point interpolation method with unequal- rank polynomial basis (URPIM). This method uses one-rank higher polynomial interpolation for displacement than that for pore water pressure，but the rank of radial basis for them is the same. The results display that URPIM can decrease or even avoid the curve fluctuating phenomenon resulting from numerical ripple when the same time steps，mode of point distribution and integral scheme are adopted. Furthermore，the solutions are in good agreement with those of finite element method and are of higher accuracy compared with those of the radial point interpolation method with equal-rank polynomial basis.

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SIMULATION ON SOLUTE TRANSPORT IN FRACTURED ROCKS BASED ON FRACTAL THEORY

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2004, 23 (08): -1358 doi:
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Rough fracture surface is of characteristics of fractal and can be considered as congruence of the upper and lower fracture surfaces. The rough fracture surface and the distribution of fracture apertures can be simulated by fractal theory. The simulation is made on solute transport in rough fractures by characteristic FEM based on the fracture face and fracture apertures simulated by using fractal theory. The result of simulation shows that it is more actual to simulate solute transport in fractures with its roughness considered. In contrast with the solute transport in smooth fractures with average aperture，the frontal surface of concentration in a rough fracture is more behindhand and is of characteristics of nonuniformity and anisotropy.

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RESEARCH ON STRESS-STRAIN BEHAVIOUR OF SOIL CORE ROCKFILL DAM

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2004, 23 (08): -1363 doi:
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FAULT ACTIVITY AND ITS EFFECT ON THE WEST LINE OF WATER DIVERSION PROJECT FROM SOUTH TO NORTH OF CHINA

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2004, 23 (08): -1370 doi:
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Based on field investigations of fault activity in the project region of the first stage of the west line of Water Diversion Project from South to North of China，following viewpoints are presented. (1) The NW directional faults mainly twist laevogyrately，and the SN directional ones are well developed and twist dextrorsely. (2) Because of the confining of Maerkang floor boming and Nianbao granite，the activity of faults shows a weakening trend towards SE direction. The activity and its engineering effect of regional faults such as Qingshuihebei fault present a trend of weakening，or a tend to terminating. (3) The influences of fault activity on the project are mainly the influences of the deformation of faults and fault belt and tectonic stress field on the deep tunnels，and the influences of fault on the earthquake induced by reservoir.

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STUDY ON REMEDIATION STRATEGY FOR SLOPES OF NANPANJIANG BRIDGE ON JIUXIANG-SHILIN-ALUGUDONG SECOND-GRADE ROAD

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2004, 23 (08): -1375 doi:
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Nanpanjiang Bridge，a huge bridge under construction on the Jiuxiang-Shilin-Alugudong second-grade road，is located on the gorge terrain in Yiliang County of Kunming City，Yunnan Province，China. The two sides of the Nanpan River where the main piers are located are consisted of cliffs of dolomite rock matrix. The rock masses are decomposed into rock blocks of different sizes with lot of joints and fissures，and some of them have become dangerous ones. Having taken the engineering geological conditions of the slopes of the bridge into sufficient considerations，many kinds of measures are used in the remediation works，such as pre-stressed anchored cables with connection beam，pre-stressed cables net，combined bolting and shotcrete，combined piles and sheeting crushed-stone-retaining wall，drain trench，seeding works，etc. Pre-stressed cable net is used to control the dangerous rock mass in this project，and the concept，design and construction methods of it are creatively presented. This technique can be used effectively in the remediation works for dangerous rock mass，especially when size of the rocks is big enough and strength of them is high as well. Meanwhile the design method of pre-stressed anchored cables with connection beam is also introduced in details. The slops remediation works are now under construction.

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STUDY ON MECHANISM OF DEEP FRACTURES OF JINPING FIRST STAGE HYDROPOWER STATION BY ENGINEERING
GEOLOGY ANALOGY

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2004, 23 (08): -1380 doi:
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Jinping hydropower station is located at the middle stream of Yalongjiang River and the west side of Jinpingdahewan on the boundary of the Yanyuan County and the Muli Zang autonomous county of Sichuan Province. The deep fractures are well developed at the left abutment slope. By comparing engineering geology conditions of four slopes near the dam area，it is concluded that the regional crustal movement and magnitude of the tectonic stress are the essential causes and prerequisite for deep fractures. The slope structure and rock property provide material foundation for deep fractures. From viewpoint of mechanics，the mechanism of the deep fractures is similar to the deformation mechanism of left slope of Santan，which belongs to typical toppling deformation.

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ANALYSIS ON INFLUENCE OF ROCK INTERLAYER ON BLASTING

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2004, 23 (08): -1385 doi:
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In rock blasting，the rock interlayer has great influence on the quality and effect of blasting. The stress wave induced by the explosion may change during spreading through different interfaces，which is one of the reasons of the influence of rockinterlayer on blasting. With theoretic analysis and engineering example，some methods are introduced to improve the quality and effect of blasting for different rock interlayers.

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STUDY ON CHARACTERISTICS AND ENGINEERING EFFECTS OF HIGH SLOPE IN DAM REGION OF A HYDROPOWER STATION IN
SOUTHWEST CHINA

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2004, 23 (08): -1388 doi:
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The high slope on both banks in the region of lock site of a hydropower station in southwest China，has the surface with severe weathering and relief，and has predominant flexure-tension fracture distortion. So the disaster，such as falling，desquamation，happens from time to time. Thus it appears especially important to accurately evaluate the characteristics，stability and hazard degree of the slope. Based on the site survey of engineering geological environmental condition and comprehensive analysis，firstly，the characteristics of the high slope on both banks are detailedly studied，such as structure types，combination between structural plane and slope surfaces，weathering of rock mass and the physical and mechanical property. Then the quantitative grades are given to the quality of rock mass. Accordingly the stability and the potential engineering effects are synthetically evaluated combined with actual slope. Finally，It is concluded that the stability of the slope on both banks is poor，especially on right bank. This situation will have a strong influence on lock site and water intake under the slope.

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REVIEW ON DAM CT TECHNIQUE

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2004, 23 (08): -1394 doi:
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After introducing the principle and classification of computerized tomography (CT) technique，the applications and progresses are discussed of elastic wave tomography，electromagnetic wave tomography and resistivity tomography in detection of incipient fault for dam. The practical examples demonstrate its application effects and show that there is a broad prospect for tomography technique in detection of incipient fault for dam.

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LOAD TRANSFER METHOD FOR DETERMINING VERTICAL BEARING CAPACITY OF ROCK-SOCKETED FILLING PILE

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2004, 23 (08): -1398 doi:
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The analytical method of load transfer is adopted to study the load transfer mechanism of rock-socketed filling pile in this paper. According to the different behaviors of work-softing or work-hardening of soil in engineering practice，a uniform load transfer model is established for various types of soil or rock. Based on this model，the relation formula between the settlement and load of pile top is deduced，which can consider side resistance force of soil (rock) along the pile shaft，the end resistance at the bottom and the influence of slime. As a result，the vertical bearing capacity of rock-socketed filling pile may be determined by the settlement of pile top. The calculated results by the presented method show a good agreement with those measured from test pile.

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TESTING STUDY ON RATIO OF DYNAMIC SHEAR MODULI AND RATIO OF DAMPING FOR RECENTLY DEPOSITED SOILS IN NANJING
AND ITS NEIGHBORING AREAS

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2004, 23 (08): -1403 doi:
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Through analyzing the test results of free vibration column apparatus on recently deposited soils of flood plain including clay，silty clay，mucky silty clay，silty clay and fine sand interbedded strata，silt and fine sand in Nanjing and its neighboring areas，the effect of confining pressure，shear strain and soil structure property on dynamic shear modulus G and damping ratio l is investigated in detail. The confining pressure has a significant influence on the dynamic shear modulus ratio. The more the effective confining pressure increases，the less the dynamic shear modulus ratio G/Gmax reduces with shear strain increasing. After normalized by Gmax，the values G/Gmax of different confining pressure scatter in a narrow band and their discreteness is small. Compared with the test results of Seed and Idriss for silty clay and fine sand interbedded strata，the value of shear modulus ratio changes between lower boundary of sand and saturated clay curve proposed by Seed and Idriss. Those values are close to lower boundary of sand and keep away from Seed-Idriss saturated clay curve，so it may be concluded that the dynamic shear modulus of silty clay and fine sand interbedded strata is similar to that of sand. For sand soil and silty sand including mucky silty clay，the value of damping ratio approaches the lower boundary of sand l-g curve proposed by Seed and Idriss. Damping ratio is smaller than that of sand soil when the shear strain is the same. However，for silty clay and fine sand interbedded strata，the date of damping ratio falls between upper boundary of sand and Seed-Idriss mean curve. So，the damping ratio of silty clay and fine sand interbedded strata is higher than that of general sand. By comparison between the test results and the variation range of G/Gmax-g and l-g curves of sand recommended by Seed and Idriss，it is concluded that the silty clay and fine sand interbedded strata should not be simply treated as sandy soil or silty clay. Based on the test results and theoretical analysis，the average curves，recommended values and envelopes of dynamic shear modulus ratio G/Gmax and damping ratio l versus dynamic strain g for recently deposited soils in Nanjing and its neighboring areas are presented. But the proposed values can only be used as reference because of the complexity of l and. G