Table of Content

    24 August 2009
    Volume 39 Issue 4
    Fluid-solid coupling analysis of surrounding rock mass stability and water inflow forecast of a tunnel in a karst zone
    LI Xin-Ping, DAI Yi-Fei, HU Jing
    Abstract ( 334 )   PDF (1144KB) ( 1573 )   Save
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    Taking Wuchiba tunnel as the engineering background, a three-dimensional geological model of tunnels in karst regions was established. Characteristics of rock stress around the tunnel in the direction of tunnel axes and vertical tunnel direction of the axes  were analyzed, based on the conditions of fuid-solid coupling. Relations of the stress around the tunnel and the distance between the cross sections and the underground river, and the surface karst depressions as well as the relationship between working conditions were discussed. Displacement variation of a typical crosssection under a variety of working conditions of the tunnel wall was analyzed. Water inflow to the tunnel was analyzed and forecasted by means of the finite element method. The obtained results can provide references for the analysis of rock mass stability and prediction of water inflow of tunnels in karst zones.

    Integrated advanced geological prediction methods and engineering application of karst tunnels
    ZHANG Qing-Song, HU Zhen-Hao, LI Shu-Cai
    Abstract ( 309 )   PDF (2064KB) ( 1361 )   Save
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    Engineering geological and hydro-geological conditions are highly changing and complex in karst developing district of tunnels. Water inrush, mad (sand) flush, collapse and some other geological hazards often occur in the construction of karst tunnels, which often bring about great casualties, economic losses and environmental destruction of karst hydrogeology. According to the applicable scope, merits and drawbacks of different geological prediction methods, an integrated advanced geological prediction methods wasput forth to  predict  water inrush, mad flush, fault fracture zones, karst classification and stability analysis of rock mass. A multi-step warning and prediction system was established, which included macroscopic, long-term, short-term geological prediction methods and geological precursory prediction methods. The multi-step warning and prediction system was successfully applied in the construction of the Qiyueshan Tunnel and others.

    The mechanism and prevention technology of the inrush  water disaster warning of karst tunnels
    MA Shi-Wei, MEI Zhi-Rong, ZHANG Jun-Wei, DU Jun
    Abstract ( 305 )   PDF (562KB) ( 2118 )   Save
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    The formation and occurrence of inrush water disaster of karst tunnels must have four basic conditions: special geological structure, sufficient filled material, abundant groundwater resources and manmade excavation disturbance. A three-grade monitoring warning scheme of inrush water disaster of karst tunnels was first presented  based on the analysis of water pressure, water quality, rock displacement, and stress of steel arches. Then, the inrush water disaster warning system of karst tunnels was also developed. In-situ experimental results in the Liuyang River tunnel of Wuhan-Guangzhou railway and the  Dazhiping tunnel of the Yichang-Wanzhou railway showed that, the inrush water disaster warning system of karst tunnels adapts well to the complicated environment  with good stability. Popularization and application of the system are conducive to safe construction of large tunnel. Finally, the regulation principle of inrush water disaster of karst tunnels was presented.

    Application of the land sonar method in tunnel defective geological advanced prediction
    QIU Dao-Hong, ZHONG Shi-Hang, LI Shu-Cai, ZHANG Le-Wen, SU Mao-Xin, SUN Huai-Feng
    Abstract ( 348 )   PDF (1775KB) ( 1956 )   Save
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    Unexpected geological disasters such as faults, karst caves, water and slurry gushes often happen during tunnel construction, which can bring momentous disaster and un-estimated economic loss to construction. The precise and immediate forecast in advance about geological conditions in front of the tunnel face has an important practical value in engineering. As a variation of the seismicreflection method, the land sonar method is a kind of advanced geology prediction method ahead of the tunnel face. Compared with ordinary detection methods, this method hasmany merits such as high resolution ratio,avoiding lots of disturbed waves,continuous collection for single trace, high energy of reflection waves and minimum offset distance. Based on the detailed investigation of engineering geological conditions along a tunnel, the land sonar method was applied to detect  faults and karst caves in front of the tunnel face. The results show that the land sonar method has a high accuracy to find faults and karst caves, which can also be an assistant method to the water detection.

    Numerical simulation study on influence factors of  the seepage volume of  submarine tunnels
    FENG Xian-Da, LI Shu-Chen, XU Bang-Shu
    Abstract ( 326 )   PDF (963KB) ( 1539 )   Save
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    The influence factors of the seepage volume in  submarine tunnels were studied by means of numerical simulation. A large number of models with different model scales and boundary conditions were built for the numerical simulation. The computed results showed that when the distance from the boundary to the tunnel profile was at least 7 times  the tunnel diameter, an accurate seepage volume could  obtained, and the fixed boundary makes the seepage volume be overestimated, while the free pore pressure boundary was  underestimated.

    Research in  field tests  of the influence factors of the TSP system signal collection quality
    ZHANG Xiao, LI Shu-Cai, ZHANG Qiang-Song, LIU Qin, ZHANG Ning, LIU Bin
    Abstract ( 293 )   PDF (1097KB) ( 1804 )   Save
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    Effectiveness of seismic wave signal collection is the precondition for ensuring the accuracy in TSP forecast. In order to improve the signalto noise ratio,  the main factors  affecting TSP signal collection quality were studied by field test, comparative analysis of field test results, and theoretical analysis method. The influence mode of the fault belt, Rayleigh wave and theanchor coupling of the detecting rod on signal collection were studied. Different coupling methods  and anchor strength of the detecting rod have different interferences on signal reception. The single-trace signal method was first  applied  to analyze the interference characteristics, and the weakening or eliminating interference method of detecting rod coupling methods  were also studied. The interference principle of the Rayleigh wave to signal collection was analyzed with the Rayleigh wave theory, and a conclusion was obtained that the Rayleigh wave influence can be significantly weakened with increasing anchorage depth.

    Impact of abnormal stress distribution near the alteration belt on rock-burst risk strength
    ZHANG Le-Wen, LI Gao, QIN Jie
    Abstract ( 259 )   PDF (456KB) ( 1715 )   Save
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    The inference of alteration zone thickness and side pressure coefficient to abnormal stress distribution was studied by systematic numerical simulation. Using the test design method of orthogonal and uniformity and  applying the analysis method of finite difference method produced regular results. On the basis of the riverside hydropower station tunnel,  the influences of the alteration zone to the distribution of ground stress and rockburst degrees were studied, and  some useful conclusions were obtained.

    Analysis of Rayleigh wave velocity criterion  for the surrounding  rock classification change of road tunnels
    ZHAO Cun-Ming, SHEN Fei-Min
    Abstract ( 314 )   PDF (1319KB) ( 1580 )   Save
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    The accurate surrounding rock classification and forecast are the important basis for properly selecting support parameters and deciding on the work  method in the process of road tunnel construction. In order to solve the problems of how to forecast the surrounding rock classification by the characteristics of Rayleigh wave velocity changes on the Raleigh wave frequency-disperse curve, the changes of surrounding rock were divided into three types, the same grade, the lower grade and the higher grade compared to the present surrounding rock condition. On the basis of the geological work principle, the Rayleigh wave velocity criterion for surrounding rock classification was given using the variety rate of the Rayleigh wave speed to depth as the surrounding rock classification. The regulations for using these criteria were also discussed. Then, the accuracy of the criterion was verified by the forecast results. An efficient in-situ test method for surrounding rock classification in tunnel construction was put forth.

    The application of TSP203 advanced geological predication about  f2-1 watery fault of the Jiaozhouwan subsea tunnel
    ZHAOYan, LI Shu-Cai, XUE Yi-Guo, LI Wei-Teng, DING Zhi-Hai
    Abstract ( 315 )   PDF (833KB) ( 1129 )   Save
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    The geological condition of the Qingdao Jiaozhouwan subsea tunnel is very complex for having plenty of high inclination-angle faults. The key point of the engineering construction is the safety when passing a watery faulu under the sea. As a mature means of advanced geology predication applied to tunnel in recent years, the TSP advance geological forecast system has advantages, such as long forecast distance, sensitivity to faults, easy of use and less affected  construction. The TSP advanced geological forecast system was used to detect the f2-1 watery fault of the Jiaozhouwan subsea tunnel. The pictures of depth migration, reflector extraction, 2D figure of result and 3D figure of result were obtained, and finally the scale and location of the f2-1 fault were determined. The obtained data about quantity and length of the fault could provide parameters for pre-grouting. The geological record of this section proved the accuracy and effectiveness of this prediction.

    Studies on combined blasting method of the TSP advanced  geological prediction
    XU Zhen-Hao, LI Shu-Cai, ZHANG Qiang-Song, LI Li-Ping, ZHANG Xiao, GAO Yang, YUAN Xiao-Shuai
    Abstract ( 338 )   PDF (1031KB) ( 1696 )   Save
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    In order to simultaneously get long distance and better precision of tunnel seismic prediction(TSP), the combined blasting method was adopted to ameliorate trigger modes of seismic signals in the TSP advanced geological preeiction. The empirical formula of the center distance between the trigger boreholes was brought forward.In addition, when the time delay errors of instantaneous detonators were  controlled under several micro-seconds or even several tenths of one micro second, and the measuring instrument was introduced to measure the  time delay error, the errors of seismic travel time information and geological predictions could be reduced. By means of the combined blasting method, seismic waves with the characteristic of both highenergy and high frequency, as well as long distance and better precision of predictions could be obtained at the same time. This method was successfully applied at the Yunwushan tunnel of the Yiwan Railway, and the Qiyueshan Tunnel and the Longtan tunnel of the Hu-Rongxi Expressway.

    The effect analysis of advanced detection of water interbed by TEM
    SUN Liang
    Abstract ( 276 )   PDF (740KB) ( 1098 )   Save
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    During   tunnel excavation processes,some geological diseases such as  water-filled or mud filled cracks and other geological faults, often occur  in front of the working face, which usually exist in a form of the water interlayer. By means of apparent longitudinal conductance quadratic differential coefficient imaging  based on the equivalent conductive plane method,the response characteristics  and the identify method of the apparent longitudinal conductance quadratic differential coefficient imaging were obtained  through the “H”type geoelectricity model. Then,  the effect of water interbed advance detection  was analyzed by way of apparent longitudinal conductance quadratic differential coefficient imaging. The conclusions can be used to direct the transient electromagnetic method in  tunnel geological forecast and to  improve the accuracy of TEM detection.

    Abnormal seismic signals in the TSP advanced geological prediction
    YUAN Xiao-Shuai, ZHANG Qing-Song, XU Zhen-Hao, GAO Yang
    Abstract ( 319 )   PDF (1307KB) ( 1305 )   Save
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    As one of the most commonly used long-term geological forecasting methods,  theTSP advanced geological prediction system, is now used successfully in many tunnels at home and aboard, which plays a tremendous role in tunnel construction and geological prediction. A variety of surrounding rock and site conditions will be encountered in the collection process of the TSP data, so the collections of the original seismic waveforms are different in many ways. Research was made  on the characteristics and causes of several common abnormal original waveforms. By adopting corresponding measures, it can  avoid  triggering and accepting abnormal signals, and more rational seismicwaves can be obtained, and the accuracy and reliability interpretation of the TSP data can be improved.

    Discussion on interface error regularity of inclined  stratum predicted by TSP
    DING Wan-Tao, LI Shu-Cai, ZHANG Qing-Song
    Abstract ( 312 )   PDF (905KB) ( 1714 )   Save
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    Based on the detection principle of TSP,the reason to produce errors of the interface of the inclined stratum predicted by TSP was analyzed. Combined with comparative analysis of engineering examples, the regularity of angle and error of inclined stratum predicted was discussed. The result showed that the  interface  of the predicted  inclined stratum would always appear later than the real interface, which had no relation with the angle between the inclined stratum and the axis of tunnels.

    The application of the TEM 3D imaging technique in geological forecasts
    SU Mao-Xin, LI Shu-Cai, LI Xiu, ZHANG Qing-Song, XUE Yi-Guo, QIU Dao-Hong
    Abstract ( 278 )   PDF (895KB) ( 1250 )   Save
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    The 2D section of apparent resistivity contour lines are usually  used in the interpretation result of transient electromagnetic (TEM). However, the 3D image is  straighter, and has more abundant information and comprehensive interpretation compared to the 2D image, which can improve the interpretation accuracy of the TEM geological forecast.  The 3D curved surface continuation method was adopted to discuss the TEM 3D imaging technique and its application in tunnel geological forecasts. [JP2]First, the 3D curved surface continuation imaging method principle was introduced. Second, the 3D curved surface continuation imaging technique characters and its application effect analysis was discussed. Finally,  some conclusions and laws were summed up in order to guide the transient electromagnetic method in  tunnel geological forecasts in order to improve the accuracy of the TEM detection.

    Application of ground penetrating radar to the geological forecast for water-bearing faults in the  Jiaozhou Bay subsea tunnel construction
    LI Wei-Teng, LI Shu-Cai, XUE Yi-Guo, ZHAO Yan, DING Zhi-Hai
    Abstract ( 280 )   PDF (861KB) ( 1272 )   Save
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    The geological conditions of the Qingdao Jiaozhou Bay subsea tunnel are complex, which include many groups of faults with a large dip angle, and therefore how to ensure the security of the tunnel in fault rich  water is a key problem in engineering construction. The application of geological radar  was introduced for detecting the fragmented rock and fissure water in F4-5 waterbearing faults in the left line of the Jiaozhou Bay subsea tunnel. For the influencing factors during data gathering and data analysis,  some measures were used to reduce the interference, and the achievements such as pseudo-color survey line graph and survey line oscillogram were obtained. The achievements depict the growth scale, position and water situation of the F4-5 fault. The parameter of the exact location and size of the fracture and the location of fracture and cracks in the fault zone were also provided. At the same time the geological forecast provided parameters for advanced grouting. The later geological compilation after the excavation confirmed the accuracy and validity of this geological radar forecast and the mentioned measures  certainly have reference mearing to ground penetrating radar application on subsea tunnels.

    Application of comprehensive geological predictionin open-cut tunnel detection
    SUN Huai-Feng, LI Shu-Cai, CUI Wei, QIU Dao-Hong, LIU Qin
    Abstract ( 284 )   PDF (1751KB) ( 1555 )   Save
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    Collapse or roof fall usually occurs at the open cut part. To solve this problem, comprehensive geological prediction is necessary.The basic principles of two widely used geological prediction methods (TSP and GPR) were introduced. These two methods were applied in detection of an opencut tunnel. The basic position of the gully and the water cut condition were determined according to  advanced geology prediction using TSP203. An opposite conclusion was  obtained that opencut tunnel would not show here. In addition, the thickness of bedrock was tracking detected using GPR, and a comparasion with the excavation was given.

    Design and implementation of a tunnel detector based on  the two time-difference method
    LI Hai-Dong, TIAN Lan, LI Shu-Chen
    Abstract ( 294 )   PDF (381KB) ( 1831 )   Save
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    Based on the two time-difference induced polarization method, a tunnelgushing detector design was proposed. A specific realization of the receive system design in the PC+MCU mode was described. A series of optimization technology in IP-voltage collection was also discussed. Finally, a measurement result of the detector based on this design was shown.

    Advanced geological prediction of filled caverns and  control of geological disasters
    ZHANG Guang-Xian
    Abstract ( 263 )   PDF (983KB) ( 985 )   Save
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    Unknown geological disasters, such as water inrush and mud gushing, are often triggered by disclosing filling cavities in the constructions of karst developing tunnels. Advanced geological prediction methods, drilling boreholes surveying and TSP were adopted for the prediction of filling cavities. And a former designed supporting program was adjusted and optimized according to the prediction conclusions. Other advanced supporting measures were also taken to support the dangerous districts, such as advanced curtain grouting, small-pipe grouting and pipe-shed grouting. In addition,  pile-cap-bridges were in troduced to handle the filling cavities under the tunnel. By this method,  geological disasters were prevented, and  construction loss was reduced, so that the construction safety of the tunnel was guaranteed.

    Application of geological radar to geological forecast in karst tunnel
    GAO Yang, ZHANG Qing-Song, YUAN Xiao-Shuai, XU Zhen-Hao, LIU Bin
    Abstract ( 357 )   PDF (1357KB) ( 2129 )   Save
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    Geological radar is one kind of the electromagnetic wave technologies with high frequency, which is widely used in geological exploration. According to the Zijingshan karst tunnel engineering during the Daguangnan Highway construction in Hubei, a continuous mode was adopted to collect signals by geological radar in order to detect an  adverse geological body. Signals collected were processed by gain control and filtering processing. Combining with the typical examples of fissure, karstcave and water-bearing rock mass, the specific characteristics of their radar reflection were analyzed, such as unorganized events in reflection of joint fissure, zonal distribution in reflection of karst fissure, hyperbola in reflection of karst caves, the decrease of frequency and energy in reflection of water-bearing rock mass. These characters are helpful for estimating the concrete position and scale of an adverse geological body and can provide a basis to protect the safety of tunnel construction.

    Research on the suitable support form of deep gob-side entry in fully mechanized top coal caving mining
    JING Hong-Wen, XU Guo-An, QU Tian-Zhi, ZHANG Chun-Yu
    Abstract ( 297 )   PDF (1424KB) ( 1198 )   Save
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    To provide guidance and basis for the selection of support form and  the design of support parameters of deep gob-side entry,the action mechanisms of two support forms, i.e. I-steel set support and bolt support with wire mesh, bar and cable were analyzed from the aspect of structural mechanics, and then  their supporting effects were investigated by physical simulation in the laboratory. The supporting principle of cable was analyzed based on the interrelation between the key bearing layer and the secondary one. The results showed  that the bolt support with wire mesh, bar and cable was  the perfect support form because it can well meet the requirement of deep gob-side entry for support, and  the primary role of the roof cable is to link the key bearing layer and the secondary one, which can greatly increase the stability of surrounding rocks.

    The laws of strata behavior for the gob-side tailgate in the  Jining No.3 Coal Mine
    ZHAI Xin-Xian, CHEN Dong-Hai, GUO Nian-Bo, GOU Pan-Feng
    Abstract ( 339 )   PDF (800KB) ( 1821 )   Save
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    Based on the surrounding rock geological conditions of fully mechanized coal face with sublevel caving and hard roof under fault affected zone in the Jining No.3 Coal Mine, the  supporting parameters of rebar-bolt and cable-bolt supporting for the gob-side tailgate with narrow pillar were designed. With roof-strata-separation instruments and borehole-peep ones, the law of strata behaviors as follows was systematically studied in the process of the driving tailgate. Roof convergence and roof strata separation between inside and outside anchored zone were much smaller. The affected zone in the process of the driving tailgate was about 50 meters. Because of serious floorheave and obvious two ribs convergence, tailgate cross-section has become reversetrapezoid shaped from the  original rectangle  after tailgate deformation. Since there are many more joints and fissures in the pillar of the gob-side tailgate, the coal body was compressed into loose material with block structure from the elastic material with bedded structure. The tailgate cross-section could meet its service requirement and coal face advancement, which demonstrated that the industrial test on rebar-bolt and cable-bolt supporting was successful. Therefore the obtained results were widely applied in the gob-side tailgate of the coal faces in the JNCM


    The inverse analysis of the vertical additional force and stability  forecast of shaft lining for thick alluvium
    WANG Zai-Quan, LUZe-Yang, ZHANG Li-Ming
    Abstract ( 338 )   PDF (1049KB) ( 1593 )   Save
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    With  exploitation, mining and  artificialprecipitation, the consolidation settlement of the soil around the shaft lining creates a vertical additional force in the thick alluvium, which is the key reason for  the rupture of the concrete shaft lining. Therefore, the determination of the additional force has important meaning to analyze and predict the stability state of the shaft lining. A new established method of  vertical additional force was put forth by the inverse analysis of strain optimization based on monitored information in-situ, and the vertical additional force in a concrete shaft lining was determined, then the developed process of mechanical state from elastic to plastic in the concrete shaft lining and the change laws of  stress and strain were gained, and a limit strain value was put forward for the purpose of monitoring an alarm in-situ.

    Numerical simulation of the energy dissipation characteristics of an excavated circular tunnel under high stress conditions
    CUI Lan, WANG Shu-Ren
    Abstract ( 286 )   PDF (640KB) ( 1358 )   Save
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    It is the key important problems in the world for research on rockburst disaster mechanism and control countermeasure of the deep mining tunnel under high stress conditions. The principal stresses distribution and energy dissipation was analyzed according to the cases of  the excavated radius, the stress level, and the non-uniform stress field of the tunnel with the  UDEC technique.The growth curves of the energy dissipation quantity and the energy dissipation ratio were concave with stress level increasing and the non-uniform stress field aggravating. The growth curve of the energy dissipation quantity was  also concave, but the energy dissipation ratio with the excavated radius increasing was almost holding constant. The concentrating zones of  principal stress difference were extended and gradually migrated from the outside to the inside in the tunnel surroundings with the non-uniform stress field aggravating. When the horizontal stresses are greater than vertical stresses,the concentrating zones of  principal stress difference in the roof usually have more serious consequences than those in both sides of the tunnel.

    Application of the high density resistivity method to surrvey huge empty water  outside of a coal mine
    MA Qi-Hua, WANG Yi-Tai
    Abstract ( 342 )   PDF (1084KB) ( 1837 )   Save
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    According to the engineering problem that the empty water seriously affected mine safety production in the Wennan coal mine, it was explored by using the high density resistivity method. Based on the study on the basic principle, the job of field data collection and trim and the analysis of these data of the high density resistivity method,  the seam mining condition could be judged by using the resistivity changes. And then the water-bearing condition of goaf to the minied coal seam (goaf) was judged  according to the size of resistivity. According to the detected result of huge empty water  outside of the Wennan coal mine, the high density resistivity method has the advantages of high accuracy rate and  strong visibility, and has  some reference value for  practical engineering.

    Study on failure mechanism and supporting technology of soft rock  roadaway in a kilometer deep mine
    LI Hai-Yan, LIU Duan-Ju, SUN Qing-Guo, WANG Huai-Xin, LIU Yu-Ping
    Abstract ( 373 )   PDF (517KB) ( 1695 )   Save
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    With the gradual deep exploitation of the mine, the surrounding rock mass in the roadway has such characteristics as high ground pressure, large distortion and  is difficult to support, which can cause difficulties to control the distortion of surrounding rock with anchor-net support and not be able to meet the demand of safe production. By means of a study on failure mechanism of the 1100 horizontal roadway in the  Huafeng coal mine, the conceptions of U-shaped supporting section and closed support were put forward, and the carrying capacity of floor and the resistance to creep of roadway were strengthened. According to the research on rheological characteristics of surrounding rock mass in a kilometer deep mine, a longer time and distance can be obtained for permanent  support, while the ground pressure around the roadway was released and became stable. Then the incompact rock block was  consolidated to unity with anchoring and grouting in permanent support, and the cohesive strengths and internal friction angles of the surrounding rock were also improved, which make the surrounding rock mass change from soft to hard and nosupported effect to support structure.Meanwhile, the bole  strengthened and the reinforcement effect achieved the purpose of  permanent safety support for the  roadway.

    Example analysis for landslide hazard remote monitoring at  the Pingzhuang west open-pit mine
    HAN Xue
    Abstract ( 368 )   PDF (1212KB) ( 1611 )   Save
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    On the basis of previous research and development of a remote real-time monitoring system, a case study of the open-pit mine slope in Ping Village was carried out, and  field tests on  landslide monitoring and forecasting were implemented. Under the conditions of working on the open-pit mine slope, remote real-time monitoring was put forth for the whole landslide process. The day of the landslide was  Months 14, 2007. According to the precious data of large-scale field test, comparative analysis was conducted to the sliding destruction characteristics, displacement and monitoring curve of the slope, which indicated that the slope increase of the monitoring curve could forecast the decrease of the stable coefficient, moreover, a sudden increase point of the monitoring curve was the feature point ofprediction. The tests showed that these methods were  scientific and effective for landslide hazard monitoring and forecasting. Comparedwith the traditional horizontal displacement monitoring method, these methods could also achieve remote wireless monitoring, and could significantly advance the forecasting time of a landslide.

    Research on supporting scheme and failure mechanism of roadway surrounding rock under complicated conditions
    HE Shan, YOU Xiao-Chun
    Abstract ( 291 )   PDF (301KB) ( 1122 )   Save
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    The complicated conditions caused by a complicated geologic structure were analyzed by starting with the  Xuchang mine′s  complicated geologic structure. The deformation and failure of surrouning  rock masses characteristics and failure mechanism were analyzed combined with physical and mechanical characteristics of surrounding rock. Safety support technology measures were proposed under the condition of complicated geological structure and high stress. The results have important reference value to the design and construction of the same type engineering.

    The detection of  gushing water in deep wells  and  the research of engineering government
    LIU Ren-Tai, LI Shu-Cai, PAN Guang-Ming, ZHANG Qing-Song, WU Wen-Dong, LI Hai-Yan, LIN Ming-Yuan
    Abstract ( 285 )   PDF (1247KB) ( 2088 )   Save
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    In the government of karst water, the law of fissure development and water-power cross-connection are  key to  engineering management. For identifying  the engineering management, the geophysical prospecting method was adopted into the engineering. The position, scale and  space law of the fissure was obtained through the geophysical prospecting method. The information ofthe water-bearing formation and the character of the containing water  were  obtained by a boring test. On the base of composite geophysical prospecting and boring test, the space law of the fissure and water-power crossconnection inside the karst was concluded, and  the proper position for grouting and drilling were chosen.This research can provide a reference  for slurry diffusion. The law of slurry diffusion was  obtained by hydraulic connectivity experiment and water-power isobar drawing. This research can direct the choosing of the grouting materials and grouting technology. The engineering efficiency can be increased and the cost can be reduced with the help of this method to choose the grouting materials and grouting technology.

    Sensitivity analysis of additional stress fields for a  circular lined tunnel subjected to the coupled action of mechanical and thermal load
    WANG Ming-Bin, LI Shu-Cai, WEI Li-Yuan, QIN Hao
    Abstract ( 226 )   PDF (691KB) ( 994 )   Save
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    According to the current situation of the coupled action of mechanical and thermal load occurring in the disposal engineering of nuclear wastes,the problem of additional stress fields for a circular lined tunnel considering the effect of the thermal response was investigated. By considering the stressdeformation characteristic of the total fields and applying the technique of series expansion, the appropriate stress functions were constructed and accordingly the complex potentials for every region were obtained. The sensitivity analyses for the hole stresses of the tunnel indicated that, compared with the unlined case, the existence of a soft liner can effectively weaken the hole stresses which will obtain a minimal value when the liner thickness reaches a  certain magnitude for a fixed liner rigidity. For a stiff liner, the stress concentration will take place when the liner thickness gets up to certain value for  fixed liner rigidity, and an  increment of the liner thickness is needed in order to decrease the hole stresses. To a certain extent, stresses resulting from  thermal expansion can counteract the hole stresses.

    Numerical simulation of rockburst on the drain tunnel in  the Jinping Second Level Hydropower Station
    XU Nu-Wen, TANG Chun-An, ZHOU Ji-Fang, TANG Lie-Xian, LIANG Zheng-Shao
    Abstract ( 319 )   PDF (1576KB) ( 1741 )   Save
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    Rock-burst is a very complicated dynamical instability phenomenon. High ground stress and its induced frequent rockbursts are major influences of tunnel instability during the survey and design and construction stages. As an important and casual construction of the Jinping Second Level Hydropower Station on the Yalongjiang River, Sichuan Province, when the drain tunnel was excavated at the depth of 1600m, there frequently occurred plenty of rockbursts, which  restricted the development of construction. Aiming to investigate the relationship between the rock-burst mechanism and high ground stress, and to effectively predict the location of rock-bursts in the drain tunnel, a progressive failure progress numerical analysis code-RFPA was used to analyze the stress, and the fitting curves of the initial stress were obtained corresponding to the site measurement. Meanwhile, on the basis of RFPA simulation, the disturbed zones in the surrounding rock mass induced by stress redistribution resulting from excavation agreed with the  rock-burst fields, which indicated that RFPA can virtually simulate the mechanism of rock-burst. 

    Study of prediction on feedback caculation of excavatedmonitor to the underground powerhouse of Xiluodu
    HAN Rong-Rong, ZHANG Jian-Hai, ZHANG Xiao, JIANG Feng, LI Jie, ZHANG En-Bao, HOU Pan
    Abstract ( 352 )   PDF (888KB) ( 1302 )   Save
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    The Xiluodu underground powerhouse cavern’s scope is huge, and the main plantand the transformer room are 28.4m and 25.0m in span. Based on the relaxation coefficient function, a new calculation algorithm of the parametric regression of the surrounding rocks was  presented to simulate the disturbance and relaxation phenomena of the surrounding rocks caused by excavation. Based on the above feedback analysis theory, the tracing feedback and prediction analysis of the staging excavation between the 1st to 10thexcavation were performed.After the parameter adjustment and feedback analysis of the 1stto10thexcavation, the precision of the prediction of the typical sections canreach asatisfactory level, which proved the availability of this method in actual construction.

    Analysis and control of pre-stressing loss in construction  techniques of anchor-eye
    WANG Qing-Biao
    Abstract ( 293 )   PDF (344KB) ( 1010 )   Save
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    The mechanism of the anchoring effect of the anchorage cable is very complicated because there are many factors including the materials, the anchor clamping, the quality of anchorage cable and the construction techniques. The effects and control method of the construction techniques on the prestressing loss were studied. Based on the analysis of anchor eye bending and its deviation, a theoretical formula of prestressing loss of friction was deduced, which accords with the  practice of engineering and has more practical meaning. The results showed that the pore theory formula for calculating friction loss works more in line with engineering practice. The hole slope of the drilling anchor holes had relativity with the loss of power, that was, when the hole slope became larger, the power loss of the anchoring cable gets larger. With the same slope  n, anchor pullloading (P) became greater as the loss of anchoring force became larger.The anchor force loss caused by channel pore forming could be reduced by the adoption of appropriate measures.

    Development of a new rock similar material
    ZHANG Ning, LI Shu-Cai, LI Ming-Tian, YANG Lei
    Abstract ( 368 )   PDF (1137KB) ( 3001 )   Save
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    Based on the introduction of research status of similar materials commonly used in recent decades years at home and abroad, and advantages and shortcomings of these similar materials were analyzed. The physical properties of modified rubber powder cement mortar, including apparent density, uniaxial compressive strength, elastic modulus and splitting tensile strength, were studied. Variation of the physical parameters with replacement rate of rubber powder and water cement ratio was summarized, and a new rock similar material was produced. The results showed that the new rock similar material can well satisfy the requirements of similar material, and it was an ideal rock similar material and worth to be popularized in other model tests.

    Analysis of structural performance on friction of bearing of the third bridge of the Jinan Yellow River
    ZHANG Hui-Qin, GAO Jian-Jun, LV Chang-Rong
    Abstract ( 363 )   PDF (379KB) ( 1392 )   Save
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    For the analysis of structural performance on friction of bearing of the bridge, this paper adopts different longitudinal restraint conditions simulating longitudinal friction of bearing by setting different longitudinal rigidity, in different conditions of dead load and live load, such as the internal force of the control section of the main beam and the bottom of the bridge tower, thelongitudinal displacement of the top of the bridge tower, and the cable-stayed cable force. The changing rule of bridge stress performance under different longitudinal restraint conditions was summerized. Then, according to the result of the bridge’s loading test, the relatively reasonable longitudinal restraint conditions of this bridge were determined. Finally, according to the actual situation of this bridge bearing,  the question that needed to be paid attention to whenwe design this type bearing was proposed. This research can provide technical reference for calculation and analysis of  a bridge by  using the type of bearing.