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2002, 21 (11): 0-0

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DYNAMIC MESO- DAMAGE MODEL OF JOINTED ROCKMASS

Li Ning1，2，Zhang Ping1，Duan Qingwei1，Swoboda G3

2002, 21 (11): 1579-1584

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Based on the wave propagation theory on the jointed media，a dynamic damage model of the cracked medium is developed with the theoretical analysis and model test to investigate the jointed rockmass behavior under the blasting pulse. The presented model is capable of capturing the meso-behavior of dynamic response of the joints and the wave propagation properties under the blasting pulse，as well as the consideration of the degradation of the material stiffness and strength by the classical continuum damage mechanics theory. Comparisons between the proposed model and the test results are also discussed. The proposed model is checked by the model test and much better correlation between the theory and the test is obtained compared with the model of Chen or Valliappan. The dynamic meso-damage tensor model and the meso-damaged damping tensor model are also proposed based on the propagation model.

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QUANTITATIVE STUDY ON THE THERMAL INFRARED RADIATION OF DARK MINERAL ROCK IN CONDITION OF UNIAXIAL LOADING

Liu Shanjun1，2，Wu Lixin1，Wu Huanping1，Wu Yuhua1，Cheng Tao2，Li Guohua1

2002, 21 (11): 1585-1589

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The quantitative characteristics of thermal infrared radiation (TIR) of rocks(granodiorite，gneiss and gabbro)around the capital area，Beijing，China，in condition of uni-axial loading，were experimentally studied. It was discovered that (1) the relationship between the rock samples average infrared radiation temperature (AIRT) and its axial stress is positive linearly related before peak stress，(2) the relationship-curve between the rock samples AIRT and its accepted mechanical energy is cubic before peak stress，(3) the IRT rises inside the samples shearing zone，while drops in its lax zone after peck stress，and (4) the tendency of the AIRT variation of pre-damaged rock samples is similar to that of intact rock samples except its fluctuation. Finally，the functions between the samples AIRT and its axial stress，and the relationship between the samples AIRT and its accepted mechanical energy，are quantitatively given. Besides，the physico-mechanical mechanism of earthquake remote sensing as well as its TIR precursors is discussed.

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ANALYSIS ON THE RELATIONSHIP BETWEEN STRESS DISTRIBUTION ON INTERGATED COAL BESIDE ROADWAY DRIVING ALONG NEXT GOAF AND DAMAGE OF SURROUNDING ROCKS

Wang Weijun1，Feng Tao1，Hou Chaojiong2， Zhang Ximei2

2002, 21 (11): 1590-1593

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The high abutment pressure on the integrated coal beside the roadway is one of the reasons to lead to floor heave and affect the stability of the roadway driving along next goaf . On the basis of analyzing stress situation of the roadway，the abutment pressure distribution of the integrated coal beside the roadway under given deformation is studied by damage theory. And the relationship between abutment pressure distribution and some parameters such as the thickness of immediate roof and coal seam，the elastic modulus of the strata，is analyzed. The presented result is important for the study of heave mechanism and control.

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UNSYMMETRY OF SCALE TRANSFORMATION OF ROCK MASS ANISOTROPY

Zhao Yangsheng1，2，Wang Xiaohai3，Duan Kanglian2，Yang Dong2

2002, 21 (11): 1594-1597

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On the basis of fractal observation and research results for fracture strike grouping distribution，a scale transformation expression of rock mass anisotropy is presented for linear density of fracture and permeability. And a vital conclusion is put forward：that is，the unsymmetry of scale transformation of rock mass anisotropy is proved by numerical and analytical analyses. Only under very few conditions with a single group fracture or the fractal dimensions equal for all of group fractures，there is an invariable of scale transformation of rock mass anisotropy. This natural law will help us to study rockmass mechanics of anisotropy and macro or micro- mechanics.

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TIME-EFFECTIVE MODEL OF SEDIMENTARY ROCKS

Yu Tiantang1，Lu Yingfa2，Shao J F 3

2002, 21 (11): 1598-1601

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A time-effective model of sedimentary rocks is presented. The inherent anisotropy of this kind of materials is described with a scalar anisotropy parameter. The time effect is considered with a damage factor. The uniaxial compressive strength is the function of time，microstructure tensor and stress. A complete plasticity model describing the deformation process in anisotropic sedimentary rocks is given. Several triaxial tests are simulated with the presented model，the results show the inherent anisotropy and time-dependent behavior in sedimentary rocks can be efficiently described with the model.

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INVESTIGATION ON CREEP DAMAGE CONSTITUTIVE THEORY OF SALT ROCK

Yang Chunhe1，Chen Feng1，Zeng Yijin2

2002, 21 (11): 1602-1604

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The damaged behaviors induced by creep of salt rock are analyzed by creep experiment and damage constitutive theory proposed by H.P. Xie. The non-liner creep constitutive equation is given to represent the whole process of salt rock creep.

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VISCO-ELASTIC CONSTITUTIVE MODEL RECOGNITION OF ROCK MASS AND ITS ENGINEERING APPLICATION

Zhu Zhende，Xu Weiya

2002, 21 (11): 1605-1609

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Determining the best model from many visco-elastic constitutive models is studied. In the case of rock mass as acomplex system，rock deformations with time as output response，the best visco-elastic model is obtained with general principle of complex system model，such as least square method，nonlinear optimum technology and simulation method. Furthermore，the optimum model is applied to stability analysis of high ship-lock slope of Three Gorges. The numerical results show that the recognition of constitutive model can be used to predict engineering behaviours. These can achieve the goal for combination of theory analysis with engineering practice，and this research method may be applied for other engineering.

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WHOLE-PATH ITERATIVE RAY TRACING IN 3D MEDIA

Gao Ergen1，Xi Daoying1，Zeng Zhaofa2

2002, 21 (11): 1610-1614

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Based on Fermats principle，two-point ray tracing is studied on three-dimensional arbitrary interface. By means of one order Taylor's incompletion expansion，the algorithm of whole-path iterative ray tracing in three dimensional media is obtained. The numerical tests based on this method in three dimensional media show that this algorithm is fast in random interface velocity distribution and the results are accurate enough. At the mean time，its precision can be controlled according to requirement of ray-tracing. It offers a new kind of efficient ray-tracing method for three dimensional seismic migration and tomography.

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3D ELASTO-PLASTIC FEM ANALYSIS ON LAYERED ROCKMASS

Zhang Yujun1，Liu Yiping2

2002, 21 (11): 1615-1619

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The layered rockmass is of obvious anisotropic mechanical behavior，and its shear strength should be a function of inclination with respect to the layered planes. An empirical expression of c， waw suggested by the authors before for layered rockmass，and in good agreement with the test results. On the basis of this analysis，the constitutive equation of transversely isotropic medium and Mohr-Coulomb criteria in which c， vary with directions are employed，and a relative 3-D elasto-plastic FEM code is developed. Taking an underground opening as example，the numerical analyses are carried out by using the FEM code for two cases of transversely isotropic rockmass and isotropic rockmass，respectively，and the computation results are compared. Finally，some valuable conclusions are obtained according to this research.

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NUMERICAL SIMULATION ON THE PROGRESSIVE PROCESSES OF THE EARTH SURFACE SUBSIDENCE CAUSED BY THE EXCAVATION OF SUBWAY

Yang Tianhong1，Liang Zhengzhao1，Liu Hongyuan1，Tan Chunan1， Lu Peiyan 2

2002, 21 (11): 1620-1626

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The accident of surface subsidence at Haizhu Square，Guangzhou caused by the construction of Guangzhou Subway No. 2 tunnel is analyzed by numerical simulation code，Flow-Rock Failure Process Analysis (F-RFPA2D)，which is developed by the authers. The evolution process of rockmass failure and falling are obtained by the numerical simulation. The numerical simulation is helpful to explain the cause of the surface subsidence accident and find the correct measure to control the further failure and falling.

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Stability analysis and design considerations for the intersection opening of two tunnels

Zhang Xiqian，Wan Liangyong，Li Ning

2002, 21 (11): 1627-1632

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The numerical simulation analysis and optimal design for the intersection of diversion tunnel and discharge tunnel are conducted. The stability and strength of the bolt and shotcrete of the tunneling are simulated and checked firstly，and then the stresses in the final lining system are calculated and checked for the diversion tunnel. The later excavated discharge tunnel to intersect the former diversion tunnel is also simulated and the safety behavior is checked with the construction sequences of bolting and shotcreting and final lining. The optimal shotcreting timing and the size and the thickness of lining are proposed finally.

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INFLUENCE OF IN-SITU STRESS RELEASE ON THE STABILITY OF SURROUNDING ROCK MASSES AND GROUND SURFACE SETTLEMENT FOR SHIELD-DRIVEN TUNNEL

Ding Chunlin1，Zhu Shiyou2，Zhou Shunhua1

2002, 21 (11): 1633-1638

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Based on the running tunnel of Yuexiu park and Sanyuanli in Guangzhou metro line 2，the influence of in-situ stress release on the stability of surrounding rock masses and ground surface settlement for shield-driven tunnel is analysed by using the elastoplastic finite element method. Calculated results show that，the deformation of crown，springing and soffit around the tunnel face，and the plastic zone of the surrounding rock masses increase obviously with release of in-situ stress. As a result，the surrounding rock masses are turned from stable state to instable one，and the ground surface settlement increases greatly.

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New Method for Calculating Geostresses IN FEM ANALYSIS OF UNDERGROUND HOUSES

2002, 21 (11): 1639-1644

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A new method for calculating geostresses in FEM analysis of underground houses is presented. With this method，a continuous displacement field and a reasonable geostress field can be obtained simultaneously to satisfy the compatibility equations and equilibrium equations，and the unexpected influence of the boundary restraints on the modeled region，which is required by FEM program，is avoided. The results of 3D nonlinear FEM analysis on Ertan project are given with this method.

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NUMERICAL SIMULATION ON LAYER-CRACK AND FAILURE OF LAMINATED ROCK MASSES

Zhang Xiaochun1，Miao Xiexing2

2002, 21 (11): 1645-1650

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Non-homogeneity is the basical feature of rock material. The different mechanics feature and failure form of rock can be put up under different homogeneous degree. A numerical simulation on layer-crack and failure of surrounding laminated rock masses is processed. The thickness of layer-cracked plate is gained when layer-cracked structure is formed. At the same time，the results show that the homogeneous degrees play a key action for crack evolution in rock masses. Two failure ways，layer-cracked and local weakened failures，will be appeared in different homogeneous degree range.

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FINITE ELEMENT ANLYSIS ON SUPER-HIGH REINFORCED EARTH RETAINING WALL OF THREE STEPS

Lin Tong1，2

2002, 21 (11): 1651-1654

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By using finite element method，the major strain and stress，the minor strain and stress，shear stress，deformation and plastic zone of super height reinforced earth retaining wall of three steps are analyzed，and some valuable conclusions are obtained. The conclusions are also compared with the results obtained from in-site investigation and centrifuge modeling test of the reinforced earth retaining wall.

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REAL-TIME CT TEST OF HYDRAULIC FRACTURE PROCESS FOR JOINTED ROCKMASSES

Jian Hao1，2，Zhu Weishen2，Li Shucai2，Pu Yibin1，Qi Liangfeng3

2002, 21 (11): 1655-1662

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Using the special loading equipment made by authors for CT machine，the real-time CT testing is made on the whole process of fracture development and bifurcation of specimen with single fracture. The failure process of hydraulic fracture of rock under triaxial and hydraulic pressure is simulated. Under different hydraulic pressure，the propagation of old fracture leads to the development of new micro-fracture，and the failure of specimen finally. At the same time，the grains around fracture are compacted. The CT images，CT values and their square differences of different part of specimen are obtained. With study on the test data，the laws of damage evolution and fracture propagation are given. The threshold values of damage and fracture are defined，and a new CT-vaule-based damage variable of hydraulic fracture is derived.

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FRACTAL SIMULATION OF JOINT PROFILES AND RELATIONSHIP BETWEEN JRC AND FRACTAL DIMENSION

Xu Hongfa1，2，Li Yanru1，3，Liu Xinyu1，Liao Tieping1

2002, 21 (11): 1663-1666

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Joint profiles of natural rock can be considered as fractal curves. The curves generated by random fractal method simulating natural joint profiles in analysis will bring great convenience in researches. The fractal profiles of rock joints are simulated on the basis of Hurst exponent method，and the relationship between JRC and fractal dimension D is analysed. Furthermore，two empirical formulas with high fit accuracy are suggested，which can be used according to the specific case in practice.

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SIMULATION Testing study on roof strata displacement OF top-coal caving face

Zhai Xinxian

2002, 21 (11): 1667-1671

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Based on similarity theory，the middle-scale similar material models are repeatedly used for testing study on the characteristics of roof strata displacement during excavation of the upper-seam of contiguous coal seams. The Changcun colliery mining condition of Yima Mining Group is taken as geological model. The special emphasis is put on studying the changes of caving zone height and rock-fracture zone position in top-coal caving face of the down-seam after excavation of the upper-seam. The brick-strata-beam structure developed to higher position and rock-waste like arch-structure existing are revealed. Finally it is explained why the amount of dead load in top-coal caving face is larger and dynamic load coefficient is less.

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STABILITY ANALYSIS OF U-STEEL YIELDABLE SUPPORT

You Chunan

2002, 21 (11): 1672-1675

[PDF] 400 KB (197)

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The load-bearing capacity of the U-steel yieldable support is investigated in view of its stability，and the influence of support overlap parts is studied on stability. Some important conclusions are obtained.

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CASE STUDY ON COUNTER-MEASURE OF FOUDATION ON THICK MUCK BY METHOD OF OVERLOADING AND REMOVING SILT

Cao Yang1，Yan Ronggui1，2，Wang Guanghua3，Li Jianhua1，4，Zhan Jianbo4

2002, 21 (11): 1676-1680

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Taking the engineering in the 2nd jail of Zhongshan as an example with slide-resistance piles on thick muck foundation，the dilapidation and coast disasters there are described. The mechanism，counter-measure and handling method are discussed by overloading and removing silt. All the experience from this case can be widely used in the alluvial thick muck area.

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APPLICATION OF SOIL NAILING IN SLOPE ENGINEERING OF WEATHERED ROCKS

Chen Shiyong，Wang Yuanhan

2002, 21 (11): 1681-1684

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Taking the slope engineering of Wuhan Conference and Exhibition Center for Science and Technology as an example，the mechanism and design method of soil nailing are presented. Compared with the retaining wall of reinforced concrete which was proposed firstly，the soil nailing technique is of distinct advantage.

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USE OF HKU DRILLING PROCESS MONITOR IN SLOPE STABILIZATION

Yue Z Q，Lee C F，Law K T，Tham L G，Sugawara J

2002, 21 (11): 1685-1690

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The research and development of an innovative prototype digital drilling process monitor (DPM) are presented. DPM can automatically objectively and continuously measure and record the drilling process while a hole is being drilled in the ground. The drilling process is defined by the parameters including the drilling chunk positions，head positions，deformation and rotation，and the dynamic pressures. The prototype DPM is portable and can be easily mounted to a drilling machine. The prototype DPM is applied to slope upgrading works in Hong Kong. The factual data and results are presented from the monitoring of drilling holes for the installation of soil nails in weathered soil and rock slopes. The results show that the variations of the drilling parameters with time can provide rich and useful factual data and information for geotechnical design and verification，construction management and quality control.

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ANALYSIS ON INSTABILITY MECHANISM OF SLOPE K24 OF GUANG-LIN EXPRESS WAY

Liu Fengxuan1，Xu Dexi1，He Yan1，Yao Yong2，Li Zhen2

2002, 21 (11): 1691-1695

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Based on the geological conditions of engineering slope K24 of Guang-Lin express way，the slope sliding process and landslide form are described. According to the cause and mechanism of landslide，the rational treatment plan is proposed. It is summarized that pre-treatment and synchronous treatment are more advantageous than post-treatment for slope instability.

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STUDY ON IN-SITU STRESS AND ROCK BURST FOR SURROUNDING ROCKMASS OF HUAYINGSHAN TUNNEL OF GUANG-YU EXPRESSWAY

Zeng Jiquan，Lei Chengdi

2002, 21 (11): 1696-1701

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The measurement method and results of in-situ stresses and rock burst for surrounding rockmass of Huayingshan tunnel of Guang-Yu expressway are presented. The relationship between stress state and rock burst is discussed，and the stability of surrounding rockmass of the tunnel analysed.

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INTEGRATED ANALYSIS APPROACHES TO ROCK MECHANICS PROBLEMS*

Feng Xiating1，Hudson J A2

2002, 21 (11): 1702-1707

[PDF] 211 KB (115)

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Abstract In order to effectively cope with exponent increase of the complexity faced to the rock mechanics analysis problems and the large incompatibility existing between the information level required to model the rock mass and engineering and our obtainable information level at hand，the integrated approaches with intelligent characters are proposed. Many previous standard methods，such as precedent type analysis，rock classification，analytic method stress-based，basic numerical methods (BEM，FEM，DEM，hybrid)，and their extended numerical methods (fully coupled) to be developed，can be selected respectively or integrated accordingly. It is alternative to develop basic/fully integrated system，and internet-based approaches. These novel methods can also be selected or integrated each other or with the standard methods to perform rock mechanics analysis. Some key techniques to develop these alternative methods are discussed. It may focus in future on developing fully integrated systems and internet-based approaches. Developing an environmental，virtual facility/space shall be firstly done for this collaborative research on internet.

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NEW IDEAS AND METHODS ON GEOMECHANICAL SAFETY ANALYSIS OF TOXIC AND RADIOACTIVE WASTE REPOSITORIES IN SALT MINE

Hou Zhengmeng1 Wu Wen2

2002, 21 (11): 1708-1713

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In view of the need for geomechanical safety analysis of repositories in salt rock， failure criteria，creep rupture criteria，material models，pillar design methods and criteria for the assessment of barrier efficiency as well as investigations of the interaction between hydraulics and mechanics for the case of uncontrolled flooded repositories are necessary. The introduction of damage mechanics and of the Hou/Lux material model including damages into geomechanical safety analysis of repositories in salt rock can reduce some previous deficits in knowledge and modelling. This article will be as a part of geotechnical assessment to introduce the Hou/Lux material model，a new concept of hydro-mechanical coupling and a pillar design method as well as criteria for the assessment of efficiency of geological barriers.

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BLAST PLANNING AND VIBRATION EVALUATION IN QUARRIES

Tangchawal S

2002, 21 (11): 1714-1719

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Rock excavation in quarries is normally carried out by using explosives. The steps in planning of cutting face are based on the appropriate design for angles of cut and the optimum consumption of charge weights. Priority procedures in planning are the stability of bench excavation，vibration evaluation，and the selection for the blast patterns. The methods of analysis are described and compared with field results. From several cases of trial cut angles and changing geometry of blast dimensions，the result of an optimum pattern in a specific quarry，with respect to the acceptable global unit cost is achieved.

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SEISMIC RESPONSES OF THE SUPERSTRUCTURE-PILE FOUNDATION-SOIL INTERACTION SYSTEM

Xu Lihua1，Liu Zude1，Qian Pingyi2

2002, 21 (11): 1720-1723

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Based on model testing，the seismic responses of the superstructure-pile foundation-soil system are studied taking the dynamic soil-structure interaction into consideration. The dynamic responses of the interaction system under El-Centro (N-S，1940) ground motion excitation are evaluated by using the large general structure analysis software ANSYS. The results obtained by testing and computation are well consistent with each other，and ANSYS can be applied to the analysis on superstructure-foundation-soil interaction system.

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Self-organized criticality of liquefaction in saturated granules

Sun Yezhi，Wu Aixiang，Li Jianhua

2002, 21 (11): 1724-1728

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Utilizing the dissipative structure theory，the evolutionary process of vibrating liquefaction in saturated granules is analyzed. When the irreversible force increases to some degree，the system will be in a state far from equilibrium，and the new structure probably occurs. According to synergetics，the equation of liquefaction evolution is deduced，and the evolutionary process is analyzed by dynamics. The evolutionary process of vibrating liquefaction is the process in which the period doubling accesses to chaos，and the fluctuation is the original driving force of system evolution. The liquefaction process is also analyzed by fractal geometry. The steady process of vibrating liquefaction obeys the scaling form，and shows self-organized criticality in the course of vibration. With the increment of the recurrence number，the stress of saturated granules will decrease rapidly or lose completely，and the strain will increase rapidly，so that the granules can not sustain load and the “avalanche” phenomenon takes place.

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SIMULATION ON SEEPAGE FIELD OF UNDERGROUND WATER IN YANGJIAWANG，A DANGEROUS PIPING ZONE IN THE JINGJIANG GREAT EMBANKMENT

Yi Chaolu1，2，Guo Zhigao3，Wang Binguo4，Li Ling1，Xu Guilai5

2002, 21 (11): 1729-1734

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The seepage field of underground water in Yangjiawang of Jianli county，one of the dangerous piping zone in flooding season，on the north bank of the Yangtze River，is simulated for different water levels of the Yangtze River and different treatment models，such as model in different water levels，model of pond in high water level，model of seepage-proof walls，model of reducing-pressure wells，model to control soak and model in changing the seepage coefficiency of artificial filling，with the software of Visual Modflow developed by US geological survey. The simulation results show that the decrement of the seepage coefficiency of artificial filling will reduce the seepage damage significantly in high water level，and the reducing-pressure wells are of significant effect to prevent the bank from piping if ponds or scuttles are present.

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APPLICATION OF WAVELET TRANSFORM IN INTEGRITY TESTING OF PILES

Zhang Liangjun，Wang Jingtao，Li Guocheng

2002, 21 (11): 1735-1738

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A new“energy-fault”identifiable method is presentded for integrity detection of piles. This method is based on the energy distribution in different frequency bands and using wavelet transform. The low strain tests are carried out for various model piles with different defects. Through the multiresolution analysis of test signals，different kinds of defects could be identified. Therefore，the wavelet transform paves a new way for the signal process of pile integrity testing.

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ENGINEERING PRACTICE IS THE SOURCE OF NUMERICAL METHODS

Shi Genhua

2002, 21 (11): 1739-1739

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TECHNOLOGY ESENTIALS OF BOTTOM GROUTING OF BORED PILES

Zhang Zhongmiao，Tang Chaowen

2002, 21 (11): 1740-1743

[PDF] 551 KB (185)