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2004, 23 (15): -2489 doi:
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STUDY ON CONVENTIONAL TRIAXIAL COMPRESSION TEST OF COMPLETE PROCESS FOR MARBLE AND ITS CONSTITUTIVE EQUATION

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2004, 23 (15): -2489 doi:
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[PDF 223 KB] (1370)

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Using the RMB-150B，the rock mechanics test system，the complete stress-strain curves of marble from Ya¢an，Sichuan province，and the relationship among the yield strength，peak strength，residual strength and the confining pressure are obtained. Based on the plastic theories，the bilinear elastic-linear strain softening- residual ideal plastic model is put forward and applied to marble，and the constitutive equation of marble is obtained. The constitutive equation of strain softening is discussed especially. The results indicate that the theoretic model fits well with the test.

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BEHAVIOR OF SOFT ROCK UNDER MULTIAXIAL COMPRESSION AND ITS EFFECTS ON DESIGN OF ARCH DAM

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2004, 23 (15): -2494 doi:
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[PDF 209 KB] (886)

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The strength and rigidity of soft rock are improved under multiaxial condition compared with those under uniaxial condition. In the paper，nonlinear model is adopted，multiaxial experiment results of soft rock are applied to practice，and the numerical simulation agrees better with the reality. The calculation result is safer by considering the improvement of rock rigidity under confining pressure，but the improvement can not make up the loss of rock rigidity caused by immersion. In addition，comparison of the results of biaxial and normal triaxial experiments shows that in low stress zones the former can replace the latter. This conclusion simplifies experiment and facilitates measurement.

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STUDIES ON ACOUSTIC EMISSION CHARACTERISTICS OF UNIAXIAL COMPRESSIVE ROCK FAILURE

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2004, 23 (15): -2499 doi:
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[PDF 204 KB] (1685)

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Experiments on acoustic emission (AE) characteristics of full-regime rock failure are carried out on stiffness test machine (MTS). The mechanical properties of rocks and acoustic emission characteristics，including full-regime curves，AE counts and AE rate，are obtained. The relations among AE counts，AE rate，stress levels，and time are analyzed in detail. The results show that the Kaiser effect does not occur for every rock samples subjected to simple loading. During the initial and late stages of elastic domains，AE counts increase rapidly with the increase of stress level. But when the curve is near to the peak，AE counts obviously drop，which means that there is a relatively tranquil period. The AE rates change dramatically in different stages. In post-peak region，AE events stay evident and the AE characteristics depend on the failure type of rocks.

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MINI-CRACK DEVELOPMENT FROM A CEMENTED FRACTURE IN MARBLE SPECIMEN UNDER UNIAXIAL COMPRESSION

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2004, 23 (15): -2504 doi:
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The mini-crack development around a prefabricated fracture cemented with grout in a plate specimen subjected to uniaxial compression is tested and studied under direct SEM observation. The rock used for the test is Fangshan marble，which is relatively homogeneous in texture. Its grain size is 0.05～0.35 mm，its elastic modulus is about 78.9 GPa，Poisson¢s ratio is 0.35 and uniaxial compressive strength is 160 MPa. The specimen is a plate 25 mm×12 mm ×1.6 mm in size with a central slot about 0.6 mm wide and 6.0 mm long cemented with grout. The compressive strength of the cement grout is about one fifth of that of the marble. The major axis of the cemented fracture is inclined to the loading direction at 30°，45° and 60°. The tests are carried out in the vacuum chamber of a SEM using a vise-type loading frame. Its loading capacity is 2 000 N and the load on the specimen is measured by the piezoelectric transducer with a resolution of 0.5 N. The initiation，coalescence and recovery of mini-cracks are photographed and analyzed. The mini-cracks extend during the formation of a shear band composed of paralleled cracks，and then merge to form the fracture. The test results are compared with those with open fracture in the specimen from the previous study. It is observed that not only the load required for the crack initiation is higher，but also the crack initiation points move closer to the fracture ends in cemented fracture specimen. There are more multiply developed mini-cracks at the neighborhood of the fracture. The real fracture or fault system in earth，no matter at what scale，has lower strength，if it is filled with fault gouge or fault clay. Therefore，the test results in this paper gives a comprehensive picture for understanding and simulating the fracturing process in earth crust.

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2004, 23 (15): -2510 doi:
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[PDF 325 KB] (1101)

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ANALYSIS OF VOID CHARACTERISTICS IN SHEAR BAND OF POROUS MEDIA (1)：LOCALIZED POROSITY

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2004, 23 (15): -2514 doi:
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[PDF 188 KB] (777)

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Based on gradient-dependent plasticity，the non-homogeneous porosity and void ratio in shear band after initiation of shear localization is investigated in the paper. In order to deduce the analytical solution on local porosity，a typical micro-element body in shear band is analyzed with the assumption that the local plastic shear strain is proportional to local plastic volumetric strain. The analytical results show that porosity，void ratio，increment of porosity，increment of void ratio，rate of porosity and rate of void ratio are non-homogeneous in shear band. In the center of the shear band extremely large voids exist and in the boundary of the shear band the void ratio approaches to the initial void ratio. In the strain softening process，the maximum porosity in shear band increases gradually. Rate of porosity apparently increases with decrement of shear stress rate. Moreover，influences of shear softening modulus and internal length parameter of void ratio are investigated. Smaller internal length parameter leads to larger void ratio gradient，and the internal length parameter has no influence on maximum void ratio in shear band. However，void ratio gradient and maximum void ratio are dependent on shear softening modulus.

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ANALYSIS OF VOID CHARACTERISTICS IN SHEAR BAND OF POROUS MEDIA (2)：MAXIMUM VOID RATIO

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2004, 23 (15): -2519 doi:
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[PDF 149 KB] (835)

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Local void ratio and average void ratio in shear band are investigated as residual shear strength is reached. For quasi-brittle materials that dilate，some experimental results show that maximum void ratio occurs in critical state of the shear band. Further discussion is made based on gradient-dependent plasticity with consideration of the effect of microstructures. Local maximum void ratio is different from average maximum void ratio. Local means are dependent on coordinates，while the average stands for the whole shear band. Influences of dilation angle，initial void ratio with shear localization initiated，residual shear strength，shear elastic modulus and shear softening modulus on the average maximum porosity and on the maximum porosity are analyzed. In the process of residual deformation，maximum void ratio is reached and remains constant. The presented contclusion lays a foundation for problem of instability involved in coupling of fluid and porous media.

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3D FEM ANALYSIS ON DEFORMATION OF PERPENDICULARLY CROSSING BURIED PIPELINE IN PIPE JACKING

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2004, 23 (15): -2523 doi:
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[PDF 259 KB] (1204)

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The neighborhood buried pipelines will be damaged by movements of soil around the pipes induced by pipe jacking. The deformation of perpendicularly crossing buried pipeline in pipe jacking is analyzed by 3D FEM in the paper. The effects of the distance from pipeline to pipe jacking axis，injection slurry，alignments，material of buried pipeline，depth of buried pipeline and the elastic modulus ratio between buried pipeline and soil on the displacements of buried pipeline are studied. The analytical results show that the vertical displacements of buried pipeline are larger than its horizontal displacements. The vertical displacements of buried pipeline will reach maximum value when the pipe jacking excavation face overpasses the buried pipeline with their distance about 2 m. The main cause of the deformation of perpendicularly crossing buried pipeline is the alignments of shield towards buried pipeline. The less the elastic modulus of buried pipeline is，the larger the displacements of underground pipeline is. The elastic modulus of soil around the buried pipeline has great influence upon the displacements of buried pipeline，and the displacements of buried pipeline can be reduced through reinforcing the soil by grouting.

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NUMERICAL SIMULATION AND CONSTRUCTION TECHNIQUES OF TRANSITIONAL TRUMPET-LIKE TUNNEL OF METRO

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2004, 23 (15): -2528 doi:
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[PDF 479 KB] (857)

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The transitional trumpet-like tunnel in Line No.3 of Rail Transit System of a given city lies at the intersection between the left line and the connection line. The cross section of the tunnel is large and has many variation points，and the top of the tunnel is close to the pile foundation of Building No.30. In order to reduce the disturbance induced by the embedded excavation on stratum and control the ground settlement，it is necessary to adopt reasonable execution techniques. Based on characteristics of the trumpet-like tunnel，spectacle and auxiliary techniques are proposed，and the elastoplastic finite element method is used to simulate the process in the construction sequences.

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3D VISUAL MODELING TECHNIQUE OF NON-CONTINUOUS NON-FOLDED ROCK-MASS AND ITS APPLICATION

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2004, 23 (15): -2534 doi:
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[PDF 216 KB] (949)

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Through analysis of geometrical characteristics，engineering rock-mass is divided into three basic types，continuous non-folded rock-mass，non-continuous non-folded rock-mass and folded rock-mass. An appropriate spatial data model for 3D modeling of non-continuous non-folded rock-mass is proposed，and its corresponding data structure is constructed. A surface modeling technique is developed for building this kind of rock-mass. By using the OpenGL technique，a visual modeling system is developed and used to construct the 3D visual model of rock-mass for a given geotechnical engineering.

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FEM ANALYSIS ON COAL PILLARS IN LONGWALL MINING OF SHALLOW COAL SEAM

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2004, 23 (15): -2539 doi:
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[PDF 461 KB] (1077)

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According to the mining of shallow seam in Guojiawan Mine in northern Shannxi，China，the different schemes for remaining partition of coal pillars and regional coal pillars in practice are studied by using FEM numerical simulation. The stability of pillars in the stope and overlying strata is studied. The mechanism of the large area caving is explored. The important aspects of reasonable，safe and economic exploitation are provided for shallow seams in northern Shannxi and for similar medium-sized and small-sized mines in the west China as well.

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DETERMINATION OF HYDROGEOLOGICAL PARAMETERS BY WATER PRESSURE TEST OF STEADY-PRESSURE AND NON-STATIONARY FLOW

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2004, 23 (15): -2543 doi:
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[PDF 188 KB] (1021)

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Water pressure test is a special type of groundwater flow test with feature of short duration and test segment. The mathematical model of water pressure test with steady-pressure and non-stationary three-dimensional flow is proposed by considering the segment action as superposition of numerous point-source actions. The hydrogeological parameters are determined by using water pressure test. Even in the Lugeon¢s packer permeability test，a test of non-stationary flow is still useful. By using the observed data corresponding to time and flow，the hydro-geological parameters can also be obtained by the proposed method.

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RESEARCH ON PERIONDIC ROOF CAVING REGULARITY OF SHORTWALL HYDRO-MECHANICAL MINING ALONG STRIKE

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2004, 23 (15): -2547 doi:
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[PDF 184 KB] (768)

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Through three-dimensional similarity experiment，periodic roof caving regularity of shortwall hydro- mechanical mining along strike is obtained. The shapes of initial roof caving and periodic caving are of triangle and parallelogram plate texture. There is a certain angle between caving line and coal layer strike. The mechanical model of periodic roof caving is established and used to determine functional relationship between allowable area of hanging roof and ratio p of its span along dip to that along strike during periodic caving by approximate analytical method. The application of obtained results yielded good technological and economical benefits and has a guiding significance to the production practice of hydro -mechanized mine.

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SIMULATION AND MECHANISM ANALYSIS OF WATER INRUSH FROM KARSTIC COLLAPSE COLUMNS IN COAL FLOOR

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2004, 23 (15): -2551 doi:
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[PDF 343 KB] (1216)

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Karstic collapse columns are a kind of vertical structures typically found in Carboniferous-Permian coalfields in north China，and are widely distributed in 45 coal mine areas of 20 coalfields. Because of its hidden characteristics of the outburst and natural relationship with karstic groundwater，the water inrush caused by karstic collapse columns is more harmful to mining safety. In order to study the failure characteristics of surrounding rock masses and mechanism of water inrush caused by karstic collapse columns in coal seam floor，several situations of movements of mining work face are simulated with FLAC3D when a collapse column exists in the coal floor. Numerical simulations and experiments show that the rock failure mechanism under hydraulic pressure is of a shear-tension-pressure complex with shear as the control factor. Because of the karstic collapse column，the geological environment and rock structure in the coal floor will change，and the effective thickness of the protective layers as well as the strength of rock mass will be reduced. In addition，the stress and strain distributions are asymmetrical，and local stress concentration coefficients become larger，so that minor principal stresses of key stratum decrease further. When hydraulic pressure is larger than that of the minor principal stress of the key stratum，mining pressure and seepage as well as dilation will cause fractures to expand along the weaker directions. Fractures eventually transfix and water inrush takes place. When the border cliff of the collapse column and division line of compressive and expansive section of coal floor are coincident on the same line，the shear yield and water inrush from coal floor are most likely to take place.

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METHOD OF ELASTIC FOUNDATION BEAM FOR DOUBLE
SPAN TUNNEL PASSING THOUGH BIG WATER-ERODED GROOVE

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2004, 23 (15): -2557 doi:
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[PDF 272 KB] (1011)

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In excavation of double span tunnel，there exists a big water-eroded groove. The method of elastic foundation beam is used to cope with the situation. Acting load，calculating pattern and elastic foundation coefficient are discussed. The analytical results indicate that it is feasible to consider properly the support capacity of water-eroded groove filling. Reasonable tunnel structure and its corresponding construction method are given. The tunnel has passed though the big water-eroded groove successfully by using this method.

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STUDY ON MECHANISM OF PRESTRESSED ANCHORING CABLE
BASED ON MODIFIED SHEAR LAG MODEL

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2004, 23 (15): -2562 doi:
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[PDF 212 KB] (951)

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Shear lag model is employed to study the mechanism of prestressed anchoring cable considering the damage of rock mass and grouting material. By defining the shear damage variables of rock mass and grouting body，the damage evolvement equations corresponding to the basic principles of damage mechanics are proposed in the paper. The modified shear lag model is also given in the paper by combining the general shear lag model with shear damage of rock mass and grouting body. The model is applied to the research of resistance distribution and loading-deformation relationship of bond section of pre-stressed anchoring cable. Experimental results are in good coincidence with the theoretical prediction.

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IMPROVED METHOD FOR COMPUTING ANTI-SLIDING PILE WITH PRESTRESSED ANCHORING CABLE

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2004, 23 (15): -2568 doi:
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[PDF 197 KB] (1272)

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Aiming at the existing problems in the method for computing anti-sliding pile with prestressed anchoring cable，an improved method is proposed in this paper. According to the actual construction process and mechanical condition of the pile and the prestressed anchoring cable，the internal force of the structure should be computed in two steps. Firstly，the pile under the prestress of the anchoring cable and a part of sliding thrust will be taken into account in computation. It should be pointed out that the subgrade reaction over the slip surface behind the pile should also be taken into consideration in the calculation of the prestress. Secondly，the pile under the computed sliding thrust should be calculated and the concerted deformation of the pile and the anchoring cable must be considered. A model test on the character of the internal force of prestressed anti-sliding pile is conducted，and the pile is calculated using the improved method and the existing method. The comparison between the computation results and the test results shows that the satisfying results can be obtained by the improved method.

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SIMULATION ON FOUNDATION PIT EXCAVATION WITH FRACTURE STRENGTH THEORY AND INTERPRETATION OF OBSERVED DATA

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2004, 23 (15): -2573 doi:
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[PDF 242 KB] (1010)

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A large commercial center has been built in Tianjin，China，and the main building is 218 m high. To construct the building，a pit of 15.3 m deep，60 m wide and 150 m long has to be excavated. During foundation pit excavation，the developed cracks will affect the stress and deformation of the retaining structure. The fracture strength theory is taken into account in the constitutive relation of cracked soils. An elastoplastic finite element computer program is developed in order to simulate foundation pit excavation procedure. The calculation results are compared with the observed data from a construction site. The analysis results show that during pit excavation，tensile stress zones are developed in the ground surface behind the retaining structure. Once the tensile stress becomes larger than the tensile strength of the soil，fracture will arise in the tensile stress zone. To some extents，the existence of these cracks may decrease the stress and stiffness of the retaining structure. At the same time，the passive earth pressure increases and the active earth pressure decreases. In the crack range the active earth pressure even decreases to zero. Under this condition，the fracture strength theory is more fit for the soils than the other conventional theories and the calculated results agree well with the test data.

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RESEARCH ON COMPARATIVE TESTS OF REINFORCEMENT FOR BRIDGE-SLOPE SUBGRADE BY VACUUM WELL-POINT DEWATERING COMBINED WITH EQUAL PRELOAD

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2004, 23 (15): -2579 doi:
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[PDF 206 KB] (883)

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Based on the analysis of stress path characteristics，influence depth of reinforcement and mechanism of consolidation deformation，this paper reveals the characteristics of stress and deformation in the bridge-slope subgrade reinforced by vacuum well-point dewatering combined with equal preload. By comparison of the settlements determined by conventional grouting method and by proposed method，it is proved that the proposed method is reasonable and economical.

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MODELING STUDY ON COMPOSITE SOIL NAILING FOR DEEP EXCAVATION

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2004, 23 (15): -2585 doi:
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[PDF 331 KB] (1127)

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The composite soil nailing is a new technique developed from soil nailing for retaining excavation or improving stability of existing slope. A modeling test of the composite soil nailing is carried out in laboratory to study its behaviors and working mechanism and hence facilitate its development. The retaining structures are modeled according to the similarity rule in which the geometric length of the structure is in inverse proportion to the duration of the structure deformation and the adopted similarity ratio was one to ten. The sequential excavation and retaining are conducted during the experiment to simulate the actual construction procedures in situ. Three cases，including composite soil nailing，soil nailing and excavation without any retaining，are executed in the modeling test to compare and analyze their behaviors. Ground subsidence，rebound deformation and horizontal deflection are measured by means of displacement transducers，and the displacements inside the excavated slope are monitored by a network of surface movement markers installed inside the transparent glass side of the modeling device. The measured results show that (1) the distribution of deformations of composite soil nailing is different from those of general soil nailing and excavation without any retaining because of the cooperation of the nails and the soil-cement piles，and among the deformations，those of composite soil nailing are the smallest and those of excavation without any retaining are the largest，(2) the cooperation of the nail and the soil-cement piles in the composite soil nailing causes more subsoil participating in retaining action than in the soil nailing due to the uniform stress distribution near the slope. The deformation induced by excavation is controlled effectively and the stability of the excavated slope is improved.

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COMPARATIVE LABORATORY STUDY ON TYPICAL RED CLAY AND EXPANSIVE SOIL

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2004, 23 (15): -2593 doi:
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A comparative laboratory study is presented on the physical and mechanical indexes，strength changes of intact samples during the process of dehydration，strength changes of compacted samples after saturating，as well as the dehydration and humidity absorption capability for the red clay in Guigang，Guangxi，and weak-expansive soil and mid-expansive soil in Jingmen，Hubei. The results show that the strength of the three kinds of soils possesses different rules during the process of dehydration due to the double effects of matrix suction and fissure. Because of the different swelling properties of red clay and expansive soil，the water contents of compacted samples corresponding to the maximum of dry density and CBR after saturation are higher in different extents than those corresponding to the optimum water content. The properties of dehydration and humidity absorption of tested soils are different due to the difference in mineral compositions. Even though there are some similarities between red clay and expansive soil on the physical and mechanical indexes，but the mechanical behaviors and water-sensitivity of these two special soils are obviously different. Hence，enough attention should be paid to these problems in the practical engineering projects.

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MECHANICAL PROPERTIES OF RED CLAY UNDER
DIFFERENT STRESS PATHS

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2004, 23 (15): -2599 doi:
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[PDF 211 KB] (1418)

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Mechanical properties of red clay are related to stress variation and stress state. By using the conventional direct shear test and triaxial shear test，the original stress state，relationship of stress-strain and strength of natural clay can not be reflected actually. Instead，by adopting test with different stress paths，the stress and strain relationship of the real loading process is analyzed. The study results show that in an actual project，the stress paths should be determined according to load case and stress state so that the mechanical parameters of red clay can be measured correctly and reasonably.

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STUDY ON VARIATION OF SHEAR WAVE VELOCITY CAUSED BY SAMPLING DISTURBANCE

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2004, 23 (15): -2604 doi:
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[PDF 166 KB] (1079)

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In order to study the impact of sample disturbance on shear-wave velocity，a comparative survey was carried out both in situ and in laboratory. The results show that variation levels of shear-velocity differ according to the property of soil. For cohesive soil，the differences between the two sets of results are generally less than 11 percent with the utmost value about 13 percent. For sandy soil，the indoor shear-wave velocity is smaller than that of the in-situ test and the differences are generally under 14 percent with the utmost value of 20 percent. Such conclusion offers an objective reference to estimate the in-situ shear wave velocity through indoor test. In the same time，the differences between the two sets of results provide useful reference parameters to evaluate the disturbance level during sampling.

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APPLICATION OF KEY BLOCK THEORY TO ANALYSIS OF ROCK STABILITY FOR UNDERGROUND PLANT IN BAISE
HYDRAULIC PROJECT

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2004, 23 (15): -2609 doi:
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[PDF 232 KB] (1095)

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Key block methods are applied to analysis of rock stability for underground plant in Baise hydraulic project，including analysis of unlocated，located and random blocks，block visualization，block stability analysis and reinforcement measures. In unlocated block analysis，the geometric figure of block is analyzed by determing the maximum edge length of block according to the average joint length obtained from investigation. The location of maximum key block in cavern is analyzed and displayed，so as to determine those blocks which should be considered in reinforcement design. Based on block geometry and joint shear strength，block stability is evaluated and anchor force is suggested to assure block safety. In located block analysis，actual geometry of blocks，including concave blocks are analyzed and shown by investigation of joints in underground plant. Then the anchor reinforcement program is checked accordingly. In random block analysis，joint net simulation and random block search are introduced. In the study of key block theory applied to rock engineering，some new techniques are developed，such as block geometry analysis by assuming maximum edge length of block，concave block analysis and visualization，block stability analysis and reinforcement suggestions.

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THEORETICAL STUDY AND APPLICATION OF WEAKENING TOP COAL USING WATER PRE-INFUSION IN FULLY MECHANIZED SUBLEVEL CAVING MINING

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2004, 23 (15): -2615 doi:
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[PDF 251 KB] (948)

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It is key problem to raise the top coal recovery rate of the fully mechanized sublevel caving mining. Weakening top coal by using water pre-infusion is one effective method to solve this problem. The mechanism of permeation movement in cracks and porosity of water infused into the coal mass ahead of the working face and the weakening of the coal mass is theoretically studied. By laboratory test，the law of weakening of the coal mass deformation modulus from the water pressure are obtained and the law of weakening of the coal mass compression strength from the water-bearing ratio are obtained. The method to determine the water infusion engineering parameters，such as relative position of water infusion to the working face，the start and stop times of infusion，water-bearing ratio of water infusion，infusion volume，wetting radius，interval of infusion holes，infusion duration，infusion pressure and the hole layout，is proposed. The remarkable technical and economical effects and social benefit have been achieved by application of the study results to the working face 4309 of fully mechanized sublevel caving mining in Lu¢an Wangzhuang Mine.

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IMPLEMENTATION OF NUMERICAL MANIFOLD METHOD BY USING 3D TWENTY-NODE ISO-PARAMETRIC ELEMENT MESHES OF FEM

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2004, 23 (15): -2622 doi:
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[PDF 259 KB] (878)

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The numerical manifold method (NMM) has been widely used for 2D problems. The construction of numerical manifold covers and weight functions on traditional 3D twenty-node iso-parametric element meshes of FEM is proposed in the paper. With Lagrange multiplier，Dirichlet boundary conditions are imposed along the essential boundaries. Formulae for static analysis are given. Then it is easier to model 3D problems with curved boundary surfaces by using the NMM without fine meshing in common FEM. Linear dependency of the approximation space is studied，and a method of applying enhanced cover functions only at physical covers connected to corner vertices is proposed to resolve this problem. Thus the scale of discrete system decreases more significantly than that in conventional implementations of the NMM. Example analyses show that the error energy norms decrease dramatically to about ten percent of the corresponding FEM results both in common and volume-locking cases. Convergence rates are also studied with examples and they are approximately equal in the NMM and the conventional FEM analyses for both material cases. The compatibility of the conventional FEM procedure with the 3D NMM analytical procedure is considered from the scratch of its design，which ensures a smooth and easy interface for developing an NMM analytical system from the existing FEM procedures.

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MODIFICATION OF GOODMAN INTERFACE ELEMENT

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2004, 23 (15): -2628 doi:
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[PDF 173 KB] (1656)

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To the defects of existing Goodman interface element，a better modification method is proposed. This element is connected by innumerous springs in tangent direction and by innumerous rigid rods in normal direction. In this way，the problems of considerable large error in stress calculation and large element overlapping in the existing Goodman interface element can be avoided. The implementation of the modified Goodman interface element is given in detail in the paper to facilitate the FEM application.

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Dai Zihang1，2，Shen Pusheng2，Zhang Jianwei1

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2004, 23 (15): -2632 doi:
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[PDF 257 KB] (1053)

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In order to improve the design and calculation of laterally loaded piles，numerical analytical method of finite difference is proposed which can calculate displacements and internal forces of piles under lateral load of trapezoid distribution based on biparameter mode of foundation coefficient. The finite difference formulations of displacements of piles are deduced in details. Based on these formulations，computation and visualization programs of displacements，internal forces of piles and soil reaction are developed for design calculations of anti-sliding piles and cantilever soil retaining piles for deep foundation pits. The examples show that this method is convenient and reliable. Numerical solutions are close to real solutions when differential segments are small enough. Calculation results of displacements and internal forces can perfectly coincide with measurements and practical values by trial computations with foundation coefficients adjusted. This method is used to obtain the foundation resistant coefficients by back-calculation with the data of testing piles given. The automatic visualization by the computer program is helpful to the optimization of structural design and hence the economic benefits.

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PROCESSING OF MONITORING DATA OF BUILDING DEFORMATION BASED ON WAVELET TRANSFORM

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2004, 23 (15): -2639 doi:
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[PDF 192 KB] (1032)

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Based on the theory of wavelet transform，a new method by using wavelet transform to eliminate the noise in observed data is introduced and a calculation example is also given. The results show that denoise using wavelet transform is efficient and reliable and is particularly suitable for processing monitoring data of building deformation due to its sensitivity to the noise of data and the ability to identify useful information. At the same time it is also indicated that the key problem of obtaining good analytical results is to choose a proper wavelet function，and the decision of denoise threshold is also very important. It is proved by the results that using db3 wavelet function and soft threshold in the denoising of monitoring data of building deformation is appropriate and wavelet transform provides a new and efficient method in this field. Some problems worth noticing in practical application are briefly explained.

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SIMULATION STUDY ON DEFORMATION CHARACTERISTICS OF GROUND SURFACE IN HORIZONTAL FREEZING CONSTRUCTION OF METRO TUNNEL

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2004, 23 (15): -2643 doi:
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[PDF 177 KB] (1000)

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Freezing construction is an auxiliary method in soft and water-bearing ground. The horizontal freezing construction was firstly applied in Dabeiyao Station of Beijing metro tunnel. On the basis of the prototype engineering and the simulation theory，a set of physical model test system was established，and the freezing and thawing phenomena were studied by experiments. In the meantime，studies on the deformation of ground surface in both freezing and thawing cases were conducted. The empirical formula and the variation law are presented in the paper.

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SUBSISDENCE ANALYSIS AND CONSTRUCTION TECHNIQUE OF COMPLEX CUT WATER CURTAIN CONSTRUCTION OF YITAI PLAZA

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2004, 23 (15): -2647 doi:
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[PDF 208 KB] (1170)

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Yitai Plaza is a secondary and high-class business building invested and constructed by foreign investors. The building is located at the east of Yuexiu Park Station of second line of Guangzhou Metro. The construction of Yuexiu Park Station caused subsisdence distortion of Yitai Plaza followed by rupture of the interior hall floor of the Plaza and the rupture of the ground in front of the Plaza. According to the monitored data，such as water level variation，subsisdence and horizontal displacement of the building during construction，the effect of construction on subsisdence of Yitai Plaza is analyzed. A brief introduction is given for different complex water curtain construction techniques，such as pendular jet curtain and grouting curtain，to cope with different geological conditions.

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DETERMINATION OF BEARING CAPACITY OF DEEP CEMENT MIXING COMPOSITE FOUNDATION BY TEST

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2004, 23 (15): -2652 doi:
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[PDF 150 KB] (1626)

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It is important to reasonably determine the bearing capacity of deep cement mixing composite foundation for the safety of building. The existing methods for bearing capacity determination of deep cement mixing composite foundation by static load test are discussed in the paper. Some valuable advices are proposed based on the discussion on both static load tests of single pile and composite foundation. The static load tests of both single pile and composite foundation should be made for testing pile，but only static load tests of composite foundation made for engineering piles.

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ANALYSIS ON ACTIVE EARTH PRESSURE OF SOFT SOIL IN NAIL-ROW PILE COMPOSITE RETAINING SYSTEM

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2004, 23 (15): -2655 doi:
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[PDF 200 KB] (857)

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Soil-nail and the grouting materials enhance continuity of soft soil along soil-nail，and soil-nailed soft soil has lower active earth pressure. The nail-row pile composite retaining system preserves the above characters. The row pile will pull soft soil outside through nail when the system displacement is large. These opposite effects may lead to additional lateral pressure and make active earth pressure of soft soil bigger than the theoretical value. Based on the above analysis，the paper suggests a new calculation method of active earth pressure of soft soil according to the displacement of nail-row pile composite retaining system. The relation between system displacement and real rupture angle of soil is established to calculate real active earth pressure with the help of classical equation. Considering soft soil being harden by soil-nails，the paper makes active earth pressure discounted，and discount coefficient is related to system displacement. The analysis result is tested in the stability evaluation of a retaining structure of foundation pit.

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2004, 23 (15): -2659 doi:
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Show Abstract