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2009, 28 (06): -0 doi:
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REAL-TIME REMOTE MONITORING AND FORECASTING SYSTEM FOR GEOLOGICAL DISASTERS OF LANDSLIDES AND ITS ENGINEERING APPLICATION

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2009, 28 (06): -1081 doi:
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It is meaningful for researching on monitoring and forecasting technology of slope stability in open pit mine to prevent landslide geological disasters. Based on the mechanical principle of interaction among landslide body，landslide bed and monitoring anchor cable of slope，the mechanical principle of relative movement between landslide body and landslide bed is proposed；and the multi-factor monitoring is transformed into single landslide mechanical monitoring. The relationship between sliding force of slope and pretightening force is provided. According to the physical model experiment of landslide，the stress will change continually inside the landslide mass before the occurrence of landslide. When the sliding force is greater than the anti-sliding force，the deformation and landslide will take place，which means the change of stress will be ahead of displacement. Consequently，monitoring the alteration of stress in the sliding mass is better than that of the displacement. Based on above principle and experiment，the system of real-time remote monitoring and forecasting for geological disasters of landslide is developed，which can realize the real-time remote monitoring of perturbation. Four types of forecasting models corresponding to the system of remote monitoring are also presented. According to the field application to opencast mines slope，this new technology successfully implements monitoring and forecasting for stable condition of slopes.

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RESEARCH ON UNLOADING AND ZONATION OF ROCK MASS DAM FOUNDATION EXCAVATION—A CASE STUDY OF XIAOWAN HYDROPOWER STATION

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2009, 28 (06): -1091 doi:
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The excavation has induced a series of unloading deformations and failure phenomena of rock mass including loosening and shearing deformation of existing discontinuities，and outburst and flaky failure of intact rock. The attitudes of the new failure planes are nearly parallel to the excavation surface；and the planes mostly are distributed within the depth of 4–6 m. The unloading deformation and failure have led to a notable decrease of integrality of rock mass，however，the main courses of relaxation are completed in several months. Since the excavation unloading is actually an energy release course whether it is provoked by excavation of rock mass or natural cutting of rivers. There is a clear distribution regulation for the deformation and failure phenomena，so it is suitable for investigating the unloading zones by the energy analysis method. A strain energy method for unloading zonation is presented，and the application of Xiaowan Hydropower Station has confirmed its feasibility and efficiency.

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RESEARCH ON ACCELERATION VARIATION CHARACTERISTICS OF CREEP LANDSLIDE AND EARLY-WARNING PREDICTION INDICATOR OF CRITICAL SLIDING

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2009, 28 (06): -1099 doi:
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The process of the landslide from beginning deformation to global sliding failure generally includes the initial deformation，constant speed deformation and accelerated deformation. Different deformation stages have their own different characteristics. The understanding of inherent characteristics of various stages to provide the basis for landslide warning and forecasting is the hot issue for scholars. Based on a large number of landslide deformation monitoring data，the change laws of accumulative displacement，deformation rate，acceleration，etc. are researched；and it is found that the changes of acceleration performance have different characteristics with accumulative displacement and deformation rate. Over the period before the landslide reaches critical sliding stage，the acceleration value is basically around 0. While landslide is under critical sliding stage，the acceleration is suddenly increased and shows significantly catastrophic characteristics. In other words，the acceleration before and after the landslide is under critical sliding stage shows completely different characteristics. Aiming at the above characteristics，the early-warning prediction indicator d for critical landslide sliding is proposed based on the acceleration. According to the indicator，automatic early-warning predication of critical landslide sliding is expected to achieve.

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DISPLACEMENT FRACTAL PARAMETER HURST INDEX AND ITS APPLICATION TO PREDICTION OF DEBRIS LANDSLIDES

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2009, 28 (06): -1107 doi:
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Based on systematic analysis of the composition and destabilized law of displacements of the debris landslides，a detailed research is performed on the dynamic features of the nonlinearity，catastrophe and fractal dimension decrease in the destabilized process in terms of the basic principle of fractals. Firstly，the displacement dynamic parameter of fractals—displacement Hurst index is determined by means of R/S analysis method. Secondly，taking the typical debris landslides—the Xintan landslide and the Huanglashi landslide as the practical examples，the correlation between the Hurst index of displacement and the stability of the Huanglashi slope is carried out；and the computation of the Hurst index of displacement during the destabilized process of the Xintan landslide is completed. It is found that the Hurst index of displacement of the Xintan landslide decreases before the destabilized time of the landslide；and the occurrence time of the Hurst index decrease agrees well with the destabilized time of the landslide. The above computational results show that the Hurst index of displacement is an effective nonlinear parameter of fractals for evaluating debris slope stability and it can be used in the nonlinear dynamic prediction for the destabilized trend of the debris landslides.

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APPLICATION OF ROCK STRAIN SOFTENING MODEL TO NUMERICAL ANALYSIS OF DEEP TUNNEL

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2009, 28 (06): -1116 doi:
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Along with the construction of underground caverns in depths，the stability of deep underground cavern excavation is a hot issue. According to the special mechanical behaviors of rock in deep tunnel，the strain-softening model is more suitable for numerical analysis. First，the mechanical properties of surrounding rock in deep tunnel and rock strain-softening model are simply analyzed；and through a simple numerical loading example of rock，the stress-strain computation results of Mohr-Coulomb elastoplastic model and strain-softening model are analyzed. Then，a simple circle deep tunnel numerical analysis is carried out；and the comparative analysis of computation results of Mohr-Coulomb elastoplastic model and strain-softening are analyzed；mainly for the analysis of the surrounding deformation，plastic zone and factor of safety. Finally，the strain-softening model is used to the deep underground caverns of Liangjiaren Hydropower Station；and the stability of underground caverns is evaluated. The results show that the deformations of both sides of main cavern and the junction cavern are larger，more dangerous than other places. The support of the both sides of main cavern and junction cavern should be considered.

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LARGE-SCALE SHAKING TABLE TEST FOR VIBRATION-ABSORPTION MEASURES OF PORTAL SECTION OF HUANGCAOPING TUNNEL NO.2

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2009, 28 (06): -1128 doi:
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In order to study the effects of vibration-absorption measures in mountainous tunnel during earthquake，the entry portal area of Huangcaoping Tunnel No.2 located on National Highway No.318 is selected as the prototype to conduct large-scale shaking table test. Firstly，the whole test scheme is systematically introduced，including the test facility，the design of similarity ratio，the design of mould case，the similarity materials，the layout of measure sensors，the wave input and the load subsequence. Then，combining the test result analysis，the sector of the portal area that needs seismic protection is researched；and the effects of vibration-absorption measures such as lateral buffer layer，longitudinal buffer layer，and reinforcing surrounding rock with systematic bolts are analyzed. The results show that from the entry to the deep locations，the earthquake-induced effect decreases step by step，and gets stable at the distance of 120–150 cm in model(48–60 m in prototype)，which can be considered as the most important zone for aseismic design. The results also show that setting lateral buffer layer and reinforcing surrounding rock with bolts are both effective ways to decrease the dynamic earth pressure and the liner acceleration；but the latter is relatively weaker than the former. Properly setting longitudinal buffer layer can effectively reduce the dynamic strain to an acceptable level for project safety. Finally，the some suggestions are put forward that synthetical measures for vibration-absorption should be adopted for aseismic safety design of mountainous tunnel portal area on the basis of the above results.

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ASYMMETRIC DEFORMATION MECHANISM WITHIN INCLINED ROCK STRATA INDUCED BY EXCAVATION IN DEEP ROADWAY AND ITS CONTROLLING COUNTERMEASURES

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2009, 28 (06): -1137 doi:
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The asymmetric deformation characteristics of surrounding rock after excavating and supporting of deep roadway within inclined rock strata，its failure mechanism and coupling control countermeasure are investigated by numerical simulations. Some typical applications of engineering cases are also presented. It is indicated that the deformation failure is significantly influenced by a key position of obtuse angle between roadway sections and incline directions of rock strata. Its failure mechanism can be explained by the discrepancy of deformation between interlayer shearing slip and high-stress squeezing，which is induced by the asymmetric structure of rock masses. For reducing the effect of asymmetric deformation，the asymmetric coupling control countermeasure is put forward based on the research result，which means that the key position of surrounding rock that may produce deformation discrepancy should be reinforced by anchor cable and floor bolt after bolt-net- anchor coupling support. Through numerical simulations and engineering applications，it is demonstrated that the strategy of asymmetric coupling support can definitely decrease the discrepancy deformation at the key position of surrounding rock and effectively enhance the stability of roadway surrounding rock masses.

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ANALYSIS OF DEFORMATION AND STRESS CHARACTERISTICS OF HIGHWAY TUNNELS ABOVE MINED-OUT REGIONS

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2009, 28 (06): -1144 doi:
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It is of challenge and emergent problems for hazardous assessment and treatment technology for the mined-out regions under the highway with bridges and tunnels. Based on the Fanshuigou bridge—Shipogou tunnel project which is through the mined-out regions in Liulin section of Qingdao—Yinchuan highway，the three- dimensional computation models have been built by using the MIDAS/GTS finite element program；and numerical analyses of the ground deformation response，and tunnel lining and bridge structural deformation as well as their structural forces using FLAC3D are performed. The processes are generated in the step-by-step mining region for treatment after mining coal in Tongde area. And then，the double-layered Shipogou tunnel is excavated and Fanshuigou bridge is constructed. The surface deformations under different working conditions have been revealed；and the ground subsidence basin characteristics and the central subsidence position have been determined. Also，the deformations and forces of key bearing parts of tunnel lining and bridge have also been predicted. Based on the hyperbolic model and grey model，a new combined weighting model of subsidence for highway tunnel through mine-out regions is built with the technique of minimal absolute values of errors，in which the weighting average is calculated with MATLAB. The engineering measurement results show that the predicted error with combining weighting model is reduced；and the acceptable results are obtained. The above-mentioned results have important theoretical meaning for guiding the practice of grouting mined-out regions and supporting of tunnels and bridges to meet the requirements of strength，stiffness and stability of tunnels and bridge structures.

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STABILITY EVALUATION OF HIGH SLOPE FOR HIGHWAYS AND OPTIMIZED SUPPORT DESIGN

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2009, 28 (06): -1152 doi:
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The high slopes of highways have many features，such as the large number，the complicated geological conditions，the high-speed construction，etc.. Based on the feature that deformation occurs frequently during construction period，a perfect operation method of optimized design is proposed with a specific case of Tangkou—Tunxi expressway construction in Southern Anhui Province. Through the work flowchart of general survey of high slope→proposing advices on partitions of optimizing design→choosing key slope→optimized analysis of key slope，the research results of optimized design for high slope are achieved. With the efforts of employer，designer and constructer，the scientific research results are employed quickly in engineering construction. Based on the combination of deformation theory and strength theory for slope engineering，the stability evaluation and geohazard controlling methods for key high slope are performed on the basis of geologic process principle. Through the stability analysis of deformation theory for slope，the modes of slope deformation and failure，the development processes of deformation and failure can all be determined. Combining with feedback of construction and monitoring data，both the present stability state and potential position of sliding surface can be analyzed. Afterwards，using the analytical method of strength stability，the required data for the design of slope support can be achieved；then the design can be optimized. Subsequently，in terms of deformation theory and the feedback information of construction and monitoring，the support results can be verified；and the further optimization can be realized. The detailed practice shows that the proposed method can realize high-speed excavation of high slope and normal service for highways.

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RESEARCH ON ABUTMENT ASEISMIC PERFORMANCE CONSIDERING INTERACTION OF SOIL，SUPERSTRUCTURE AND ABUTMENT

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2009, 28 (06): -1162 doi:
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Exciting earthquakes always cause larger displacement and settlement in abutment，which induce relative displacement between the superstructures and the bearing capacity of abutment. When the relative displacement is large enough，the superstructure will fall down and the bridge will lose its normal performance. In the past，the effects of soil-structure interaction such as uplift of foundation and yielding of underlying soil are not considered in the aseismic design of bridges. In order to evaluate the aseismic performance，the response of an abutment supported by spread foundation is analyzed under earthquake with time-dependent Newmark analysis. By utilizing discrete element method，the soil，superstructure and abutment systems are simulated by mass-spring models. In the discrete model，the pounding between the superstructure and the abutment，the elastoplastic responses of the backfill soil and the underlying soil are modeled by nonlinear springs. Moreover，the Winkler soil spring is used to simulate the interaction between the foundation of abutment and the underlying soil. The results show that the seismic isolation effect of foundation uplift is significant by alleviating pounding between the superstructure and abutment，and the plastic deformation of the plastic hinge regions at the bottom of the abutment stem is reduced. At the same time，the yielding of underlying soil also reduces the plastic deformation of abutment stem，and increases the effect of foundation uplift. However，the settlement induced by the yielding of underlying soil will make the tilt of abutment. Therefore，the soil，superstructure and abutment interaction such as foundation uplift and yielding of underlying soil should be considered in the aseismic design of bridges.

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EXPERIMENTAL RESEARCH ON TOP COVER OF SHALLOW-BURIED RADIOACTIVE WASTE DISPOSAL REPOSITORY

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2009, 28 (06): -1169 doi:
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The top cover is the important protection barrier for low-intermediate radioactive waste disposal repository near ground surface，and it will exert the important function for the long-term security of the disposal repository. Taking a proposed radioactive waste shallow-buried disposal repository as an example，combining with the local natural features and geological conditions，the issues of functionality and practicality of the top cover are discussed by the methods of geological analog and test. Based on analyzing the top cover of surface vegetation layer and aquifuge lithology characteristics，the experimental studies of anti-natural stresses corrosion and rock mechanical properties，water physical properties，and its permeability，etc. are carried out. The test results show that the natural sandy gravel can be used as the top cover surface vegetation layer；and the clay gravel can be used as the aquifuge layer，which can make the top cover structure simple，increase volumetric storage and reduce engineering cost. It can also significantly improve the strength，stability and the protection performance.

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EXPERIMENTAL RESEARCH ON TIME EFFECTS OF NEGATIVE SKIN FRICTION BEHAVIORS OF VERTICAL-LOADED PILES

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2009, 28 (06): -1177 doi:
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Under the action of the ground surcharges，field measurements for time effects of negative skin friction behaviors of three piles with different vertical loads on the pile top are adopted. Test results show that negative skin friction behaviors change with the extension of time under the action of surcharges. Ground surcharges will cause the soil settlement surrounding the piles；and the soil settlement surrounding the piles can induce negative skin friction in piles. At the initial stage of surcharges，the additional settlement rate of piles caused by negative skin friction gets rapidly；and the final additional settlement in piles increases with the increase of load on the pile top. Drag forces caused by negative skin frictions in piles increase gradually with the extension of surcharges loading time；and final drag forces in piles decrease gradually with the increase of load on the pile top in both vertically loaded and unloaded piles. Under the action of surcharges，the load on the pile top postpones the arrival of negative skin friction in piles. The larger of the load on the pile top is，the later the appearance of the neutral point in pile is，and the smaller the length between the neutral point and the pile top is. The time of the neutral point in piles is delayed with the increase of the load on the pile top. Increase of load acted on pile top would promote above-mentioned phenomena. It may be useful for the research of negative skin friction behaviors of piles.

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FAILURE MODE AND STABILITY ANALYSIS OF LEFT BANK ABUTMENT HIGH SLOPE AT JINPING I HYDROPOWER STATION

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2009, 28 (06): -1183 doi:
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Because of complex geological structure，the deformation failure mechanism and instability mode of high rock slope are usually very complicated. The deformation and failure mode are analyzed by the base friction experiment during the excavation of left bank slope at Jinping I Hydropower Station. The experimental results show that：(1) the failure mode is sliding and fracturing；and (2) rock masses are cut into instable blocks by lamprophyre veins X and fault f42–9，and then fail. Based on above-mentioned results，a numerical model of the high rock slope in left bank is built with FLAC3D；and the joints and faults are modeled with low-strength material. The results of numerical simulation in the excavation process show that the controlling factors for rock cracking and slope failure can be observed for the faults f5，f8，f42–9，SL44–1 and lamprophyre veins X. Then，factors of safety are calculated through the strength reduction method with numerical model of the high rock slope. Under natural state，the factor of safety of rock slope is 1.277；after excavation，the factor of safety equals 1.152；and the factor of safety will be 1.385 after anchorage cables being applied. The study shows that the potential instable zones of the slope by physical and numerical simulation methods are consistent；and the results are acceptable.

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STABILITY ANALYSIS OF HIGH SLOPE SUBJECTED TO HEAVY RAINFALL IN PINGTOU VILLAGE OF WUYI COUNTY，ZHEJIANG PROVINCE

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2009, 28 (06): -1193 doi:
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Based on the theorem of saturated-unsaturated infiltration，the numerical model of slope stability subjected to rainfall is developed；and the codes named USLOPE-FEM are programmed to consider the influence of increase of gravity and infiltration forces and the decrease of shear strength. Taking a high slope in Pingtou Village of Wuyi County in Zhejiang Province for example，the transient seepage and stability of this slope subjected to heavy rainfall infiltration are simulated；and the slope stability is quantitatively evaluated according to the transient pore water pressure，the stress and displacement. Numerical results show that the slope is stable in normal conditions；but after the heavy rainfall(magnitude of 20 mm/h) for 24 h，the increase of water content and the moving of zero pressure surface into slope will result in local collapsing. The results are in good agreement with the actual collapse，which verifies the reliability and rationality of the numerical model and program USLOPE-FEM. All above-achieved results are acceptable for evaluating the stability of slope subjected to heavy rainfall；and a general technique idea and references for slope treatment are also provided.

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RESEARCH ON SELECTION OF STRESS VARIABLES OF CONSTITUTIVE MODEL FOR UNSATURATED SOILS

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2009, 28 (06): -1200 doi:
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Stress variable is one of the basic elements in constitutive modeling. The debates in choosing the appropriate stress variables of constitutive model severely hinder the development of unsaturated soils. A single stress variable，i.e. Bishop stress，and its modified expression，or the recently proposed suction stress，can be used to simulate the strength of unsaturated soil，but they are incapable of deformation simulating because of their incapability reflect swelling or collapse after being wetted. There are many different forms of double-stress variables，such as the skeleton stress(or modified net stress) or the meniscus stress，which considers the influences of pore water pressure on the mechanical behaviors of unsaturated soils. Net stress and suction are most frequently used. Other forms of variables are also adopted，the common used one is the function of stress，and the other is the function of suction(or saturation)，which can preferably simulate the characteristics of strength and deformation of unsaturated soils. They are often chosen randomly without any theoretical deduction. Therefore，it is noted that stress variables should satisfy the Houlsby power equation；meanwhile，the strain variables corresponding to the stress variables should be selected carefully. The confused concept is clarified；and suitable stress variables in establishing the constitutive model of unsaturated soils are proposed.

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KARST ROCK CLASSIFICATION FOR WEST ANCHOR TUNNEL OF BALINGHE BRIDGE

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2009, 28 (06): -1208 doi:
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Karst is fully developed in the surrounding rock of west anchor tunnel of Balinghe Bridge. The rock classification is considered as grades II to IV during the survey. In accordance with the actual karst excavation，advanced and initial supporting parameters should be adjusted for construction safety of the anchor tunnel. On the basis of karst geological forecast and general underground engineering rock mass classification，the physical and mathematical models of karst rock classification for the anchor tunnel are established，aiming at amending rock mass classification for different kinds of karst rocks. According to the tests of rock velocity，rock strength，as well as the extent of karst correction factor and other parameters，the karst rock classification for this anchor tunnel is determined as grade V. In fact，throughout the construction process，these measures are adopted as strong support of the anchor tunnel，such as advanced small pipe，advanced anchoring，steel frame，steel wire，shotcrete，etc.. And the bench cut method is also taken for the anchor tunnel excavation. In addition，the fractured rock and the surrounding cave are reinforced by grouting after the excavation of anchor tunnel. In other words，the parameters for initial support of the anchor-tunnel are taken by considering the rock mass as grade V. In practice，it indicates that the karst rock classification for this tunnel is reasonable，which can be taken as a reference for other similar projects.

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BENDING MOMENT CALCULATION OF CUTOFF WALL

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2009, 28 (06): -1213 doi:
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In the design of cutoff wall，it is important to get the wall¢s internal forces，especially the bending moment. Generally，the stresses and displacements with finite element method are obtained. So it is necessary to investigate the indirect calculation of bending moments with stress and displacement. The analytical results of a cutoff wall with different element types and mesh partitions show that shear locking is not so significant for the cutoff wall embedded in soil. First-order solid element and second-order solid element can get similar results of displacements；and the results are insensitive to mesh partition. Therefore，high-order elements are not always necessary in the computation. The bending moment can be well calculated both by stress and displacement. Enough grids are necessary across the cross-section if bending moment is calculated with stress. Computing bending moment with displacement needs fewer grids，but it sometimes results in fluctuation of the results. Additionally，the computed results of bending moment are sensitive to mesh partition and element type；i.e. the displacements can agree well with each other，whereas bending moments have great discrepancies with different element types and mesh partitions.

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MECHANICAL CHARACTERISTICS OF RED CLAY UNDER TRIAXIAL IMPACT LOADING

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2009, 28 (06): -1220 doi:
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The mechanical properties of red clay under impact loading are studied by triaxial dynamic test system. The test schemes include various impact loadings，various confining pressures and various numbers of impacts. The deformation and shear strength of red clay samples after impact loading are analyzed. The studies show that the stress-strain curves of clay samples subjected to impact loading are higher than those before subjected to the numbers of impacts，which show the increase of shear strength. With the increase of confining pressure，the increased values of shear strength are more obvious by increasing the numbers of impacts；namely，the reinforcement effect of red clay foundation by dynamic compaction is more obvious for deep soil layers. With the increase of impact loading in the range of testing confining pressure，the shear strength of the red clay correspondingly increases.

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DYNAMIC CENTRIFUGE MODELING TEST OF COHESIVE SOIL SLOPES REINFORCED WITH SOIL NAILING

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2009, 28 (06): -1226 doi:
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In order to prevent earthquake-induced hazards，many countermeasures are developed to improve the stability of slopes，among which the soil nailing reinforcement is widely used. The behaviors of the cohesive soil slopes reinforced with soil nailing during earthquake are investigated using centrifuge modeling tests；and the unreinforced slope is also investigated for comparison. The responses of the slope reinforced with soil nailing are measured during the test，including the time-history curves of displacements and accelerations of the slope. On the basis of the responses of the slope reinforced with soil nailing and the unreinforced slope by the comparison，the deformation rules and reinforcement mechanisms are discussed. The test results show that the nailing arrests a landslide that occurs in the unreinforced slope during earthquake. The displacement of the slope exhibits an evidently irreversible deformation accumulation that is dependent on the magnitude of seismic input amplitudes. The soil nailing reinforcement mechanism is analyzed based on the comparison of displacement distribution of the lateral sides of both slopes with introducing strain analysis of a soil element within the slope. It can be concluded that the soil nailing can significantly change the displacement distribution and reduce the shear deformation of the slope. Thus，the possible sliding can be prevented in the reinforced slope during the earthquake and the slope stability can be increased significantly.

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EXPERIMENTAL RESEARCH ON REINFORCEMENT EFFECT OF COMPOUND GROUTING ON DIABASE DIKES

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2009, 28 (06): -1231 doi:
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Selecting the representative test area，the technology of high-pressure cement-chemical compound grouting is adopted to carry out experimental research on grouting reinforcement treatment of diabase dikes for determining grouting technique，and the effect and mechanism of reinforcement，etc.. During the test，microcracks are developed in the diabase dikes；and the high-pressure cement grouting has been adopted firstly. The material of cement slurry adopts ordinary Portland cement；and the material of chemical grouting is epoxy resin with super consolidation performance，which belongs to the CW series. After the compound grouting，the single P-wave velocity of diabase dikes can reach 5 153 m/s；and its deformation modulus is in the range of 11.4–21.8 GPa；the continuity，entirety and uniformity of rock mass in the test area are improved significantly. The compound grouting achieves the desired results；and the mechanical parameters of dikes satisfy the demands of dam construction. The parameters of grouting technique are also reasonable，which can directly guide the foundation treatment construction of Dagangshan hydropower station. After some preliminary explorations，the essence of the cement- chemical compound grouting for reinforcing the rock mass can be summarized as follows. After consolidation grouting，both the mechanical characteristics of structural plane of rock mass and its combination relationship are improved；and then its integral rigidity is enhanced. It is the fine cementation of microcracks so as to reduce or eliminate the stress concentration on their ends intensively. Thus，the limit yield of rock mass and its strength are both enhanced.

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MECHANISM AND GEOMECHANICAL MODES OF LANDSLIDE HAZARDS TRIGGERED BY WENCHUAN 8.0 EARTHQUAKE

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2009, 28 (06): -1239 doi:
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Due to the extremely high magnitude，long duration of vibration and the complicated geo-environment in disastrous area，the Wenchuan 8.0 earthquake produces not only a huge number of landslides and rockfalls，but also a series of complicated dynamic processes involved in their occurrence，such as very common loosing and cracking of mountains，unique shattering-sliding，extremely powerful dynamic process of large-scale or individual rock block ejection，long distance motion etc.. They are quite different from the characteristics of landslides and rockfalls under general gravity force，and present knowledge is very limit in this field. In order to describe above-mentioned special dynamic processes of shattering-cracking，the shattering-sliding，shattering-falls and ejection are defined. Combining with the slope structures，a mechanism classification system of strong earthquake-triggered landslide and rockfall are suggested，which includes 5 categories and 14 types. In addition，the basic characteristics，dynamic processes and geomechanical conceptual models of some typical types are analyzed，especially the type of shattering-sliding for most large-scales landslides is involved. The formation mechanism，geomechanical models and dynamic features of landslides and rockfalls triggered by Wenchuan 8.0 earthquake are revealed.

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ANALYSIS OF TYPICAL SEISMIC DAMAGES OF HIGHWAYS IN WENCHUAN EARTHQUAKE-INDUCED HAZARD AREAS IN SICHUAN PROVINCE

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2009, 28 (06): -1250 doi:
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A comprehensive summary of the various damages on the national and provincial highways in Sichuan Province after the Wenchuan 8.0 earthquake is presented. Typical features of the damages on highway bridges，tunnels，subgrade and pavement have been given. The reasons of earthquake-induced damages have also been outlined from the geological and engineering viewpoints. There is close relation between the destructive degree of bridge and the distance of the earthquake fault. The destructive degree of tunnels is not only related to the distance of the earthquake fault，but also related to tunnel surrounding rock lithology. The soft-hard alternant sediment rock tunnels near the earthquake fault have been seriously destroyed while the granite tunnel has slight damage. The seismic damage of the side slope is closely related to the distance of the earthquake fault，the rock lithology of the side slope and the slope angle. The secondary geological disaster is very serious，which is caused by collapse and landslide of steep slopes formed by granite rock，lime rock and sand rock near earthquake fault.

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EFFECT ANALYSIS OF STRUCTURAL SAFETY OF TYPICAL LARGE DAMS IN WENCHUAN 8.0 EARTHQUAKE

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2009, 28 (06): -1261 doi:
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Based on a field investigation on large hydropower engineering of seismic region after Wenchuan 8.0 earthquake，the main earthquake-induced hazards types of large dams are analyzed. The influence of the distance between dam and seismic center，foundation reinforcement and structural types of dams on structural safety of typical large dams including Baozhushi gravity dam，Shapai arch dam and Zipingpu concrete faced rockfill dam，are studied. The standards of aseismic performance for super high dams of 300 m and reservoir-induced seism(RIS) are also discussed. The main results of this research can be summarized as follows. (1) The damages and behaviors of dams in the area affected by the earthquake prove that codes for aseismic design of dam are appropriate；however，aseismic design of super high dams needs further studies. (2) After proper foundation reinforcement，the strength of rock mass could be increased for improving aseismic performance. (3) Under extreme condition，the design and management of emergency preplan of large dam should be improved；and emergent platform system of valley for hydropower engineering should be developed as soon as possible. (4) How to evaluate the effect of the reservoir-induced earthquake is still the major challenge for Chinese engineers in aseismic design of large dams.

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EARTHQUAKE REACTIVATION EFFECTS AND STABILITY STUDY OF MALINGYAN LANDSLIDE IN TANGJIASHAN DAMMED LAKE

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2009, 28 (06): -1270 doi:
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Malingyan Landslide is located in the left bank of Tongkou River，which is 4 km away from the upstream of Tangjiashan dammed lake. Because of its special location，it receives much concern in the process of dealing with an emergency of the dammed lake. Based on the field geological investigations of basic landslide geological conditions，deformation and failure characteristics before and after Wenchuan 8.0 earthquake，stability of Malingyan landslide，especially after the formation of dammed lake，is analyzed. The results show that the landslide is generally stable after earthquake，but part of the former section of the upriver is possibly instable because of earthquake and water storage of the dammed lake and so on. Malingyan landslide will not put against Tangjiashan dammed lake and the comprehensive treatment at a disadvantage in the future can be saved，but more attention should be put on the former section of the landslide as it may be partially instable as a result of continuous rainfalls as well as the earthquakes. And then，the potential sliding on the upside may be harmful to some residents on the slope body. Based on analytical stability results of Malingyan and the other landslides in earthquake areas，the overall reactivation of the large-scale ancient landslide caused by earthquake is mainly controlled by its terrain slope and micro-geomorphic characteristics. The whole or part ancient landslides triggered by earthquake will be instable if it satisfies the sufficient condition，in which the terrain slope is above 40° as well as slow part changes into steep one. Not all ancient landslides are possibly reactivated by the earthquake，and this will tremendously change the common misunderstanding in the past that the earthquake will trigger the whole ancient landslide reactivated inevitably.

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MONITORING ANALYSIS OF INFLUENCE OF WENCHUAN 8.0 EARTHQUAKE ON TALUS SLOPE STABILITY AT LEFT BANK IN FRONT DAM OF ZIPINGPU HYDRAULIC PROJECT

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2009, 28 (06): -1279 doi:
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The borehole inclinometer monitoring results indicate that the talus slope at the left riverbank in front of the dam of Zipingpu hydraulic project is stable until Wenchuan 8.0 earthquake，for no significant changes of displacements are observed in the slope and no obvious direction is found in the calculated displacement vectors. The Wenchuan 8.0 earthquake has brought negative effect on Zipingpu hydraulic project，which is only 17 km from the epicenter. According to the monitoring results and field investigation，the influence of the earthquake on the talus slope can be summarized as follows. Some local collapses and cracks appear on the surface of the front slope of Dengzhanping plateau，and an obvious dislocation was produced in the joint surface between bedrock and overlying talus. The maximum offset of the joint surface is 60 to 70 mm；above the surface，the displacement increases as the elevation and reaches ground with a range of 55 to 100 mm，and the maximum value is 206 mm. The displacement is formed at a specific direction due to the earthquake；and the vector is vertical approximately to the fault of Wenchuan 8.0 earthquake. The inclination of the observed hole is remarkable with a maximum rate of 1.873‰. The deformation was influenced mainly by main shock and hardly by the aftershock. The continuous monitoring data of post-earthquake show the talus slope is globally stable.

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PRELIMINARY RESEARCH ON LIQUEFACTION CHARACTERISTICS OF WENCHUAN 8.0 EARTHQUAKE

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2009, 28 (06): -1288 doi:
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Considering the limited knowledge on the liquefaction behaviors in the Wenchuan 8.0 earthquake，the liquefaction characteristics are discussed through detailed site investigation and analyses of corresponding hydrological，geologic and in-situ tests for the specific sites. The analytical results indicate that the distribution of the liquefaction phenomena in the event is vast with the region covered by length of 500 km and width of 200 km，but the liquefaction distribution is rather nonuniform. The liquefaction is mainly located in the area of a rectangle with 160 km in length and 60 km in width；and it is distributed principally in the 6 belts，which are consistent with the local hydrological and geotechnical conditions. Moreover，three salient characteristics of the liquefaction behaviors that are different from the previous earthquakes are discovered by the investigation. It is shown that：(1) Liquefaction phenomena are observed within the regions of seismic zone with intensity VI，which has not been documented previously in Mainland of China. 10 such liquefaction sites in 5 different areas are confirmed and in 2 liquefaction sites among which the buildings are damaged directly due to the liquefaction. (2) The liquefaction phenomena in deep soils，i.e. more than 20 m in depth，occur in the shock，and the macrophenomena of more than 10 m water ejection in 4 different villages are observed；and the in-situ tests for the specific sites verify the judgment. (3) The characteristics show that the gravel soils liquefy in the shock；and the in-situ tests for the specific sites verify the reality of such behaviors. Also the synthetic analyses of sand ejection，duration of waterspout and corresponding geotechnical information all demonstrate that the gravel soil liquefaction behaviors are considerable in this earthquake.

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2009, 28 (06): -1297 doi:
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2009, 28 (06): -1298 doi:
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[PDF 82 KB] (1156)

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