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2005, 24 (12): 0-0 doi:

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2005-12期目录

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EXPERIMENTAL STUDY ON BREAKING PROCESS OF BAR-LIKE STRUCTURAL BODIES

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2005, 24 (12): 2003-2003 doi:

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The plane strain compression experiments of the samples assembling of bar-like structural bodies are conducted to study the failure and breakage mechanisms of geological materials. Under different confining pressures，the breaking processes of bar-like structural bodies with two different arrangements are observed. During the breaking process of structural bodies，it is found by experiment that the structural bodies not only slide and rotate，but also break. When the confining stress is small，strain softening，rapid stress drop，volume inflation and lateral extrusion can be observed；while the confining stress is large，strain hardening，volume contraction and lateral intrusion become prevalent.

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THEORETICAL ANALYSIS AND EXPERIMENTAL STUDY ON RELATION BETWEEN ROCK PERMEABILITY AND TEMPERATURE

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2005, 24 (12): 2009-2009 doi:

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The physicochemical and structure properties of rock will change obviously under high temperature，which causes extending of fracture，dehydrating and vaporizing of mineral and changes of rock porosity and permeability. Based on thermo-elastic theory and column test results，the positive index relationship between rock permeability and temperature was deduced，and temperature threshold value was validated theoretically. When temperature begins to increase，the rock permeability increases slowly. When the temperature increases to a certain value，the speed of permeability rising increases rapidly；and this temperature is called initiation threshold value. After the temperature initiation threshold，the permeability of the rock rises quickly. The study of the relationship between rock permeability and temperature offers the theoretical foundation for the studying of multi-field coupling question under the high temperature. It gives theoretical support for permeability of petroleum thermal exploitation and for nuclear waste safety disposal.

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A NEW EMPIRICAL FORMULA MODEL FOR SETTLEMENT PREDICTION OF EMBANKMENTS

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2005, 24 (12): 2013-2013 doi:

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Lots of engineering examples show that the exponential curve models，for either single-stage loading or multi-stage loadings，can well predict foundation settlement，but they have shortcomings. A new type of exponential curve model，coupled with rheological term for soft soils，is put forward based on the calculation formula of modified secondary compression under absolute time coordinates. The parameters are back-analyzed with the optimization technology according to the measured settlements. It is proved that the new model holds higher prediction accuracy and can reasonably reflect the creep course of soil framework. Hence，it has referential value to practical engineering.

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DEFORMATION AND FAILURE MODES AND REINFORCEMENT METHODS OF ANCIENT CAVERN GROUP IN LONGYOU COUNTY

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2005, 24 (12): 2018-2018 doi:

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An ancient cavern group was found in Longyou County of Zhejiang Province. It consists of 24 caverns. The finding of it evokes attentions of many scholars in the world. Field investigations were carried out；and it is found that there are many failures in the caverns. The common failures occurs at vault and pillars. There are also some cracks in the sidewalls，vaults and pillars in the integrity caverns No.1–No.5. The vault around 1–1 pillar of cavern No.1，the common wall between cavern No.1 and No.2 and the vault of cavern No.2 etc. all need to be reinforced. In order to protect the caverns，numerical analyses were also done to study the failure mechanism of the caverns. According to the field investigations and numerical analyses and on the basis of“safety first”and “rehabilitation but not change the natural form”，the reinforcement methods were proposed.

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PHENOMENOLOGY RESEARCH ON DEFORMATION AND FAILURE MODES OF SLOPES COMPOSED OF ARGILLACEOUS LIMESTONE OF THE THIRD NUMBER OF BADONG GROUP (T2b3) IN NEW SITE OF FENGJIE COUNTY OF THREE GORGES RESERVOIR AREA

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2005, 24 (12): 2029-2029 doi:

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Slopes in the new site of Fengjie County，Three Gorges Reservoir area，are the most concerned problems among prevention of geological hazards and protection of slopes，because of their occurrence mechanism of deformation and failure and special property of their deposits. The stratum of the argillaceous limestone of the third number of Badong Group (T2b3)，is one of the argumentative focuses among scientific and engineering domain. The following viewpoints on the occurrence mechanism of deformation and failure of argillaceous limestone are obtained with phenomenology research：(1) Property of argillaceous limestone is fragile and rock mass strength decreases and crisp structure are formed by infiltrative weathering；(2) Slope rock mass，by compression cracking and sliding along the steep and moderate steep plane，produces the gravitational bend phenomena of loose structure，one by one cascade，resulting in remarkable decrease of rock structural strength；(3) The deposit composed of argillaceous limestone is almost homogeneous，irregular arrangement，without uniform sliding belt. It is not deposit of landslide or rock mass falling，but the product of slope structural decomposition in certain range；(4) Deformation and failure process of argillaceous limestone are resulted from weakness of rock mechanical property caused by weathering and from loose structure caused by gravitational bend；and finally，the whole structure of rock mass is entirely collapsed.

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CHARACTERISTICS AND MECHANISM OF SLOPE DEFORMATION AT INTAKE OF FLOOD-DISCHARGE TUNNEL NO.2 OF ZIPINPU HYDROPOWER STATION

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2005, 24 (12): 2035-2035 doi:

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The geological condition of high rock slope at the intake of flood-discharge tunnel No.2 at Zipinpu hydropower station in Sichuan is very complex. There appears evidently the toppling deformation above the soft rock strata (L9，L10) in the lower part of slope，and collapses took place many times. Through studying lots of factors，such as different substantial components of slope，character of geological structure，excavation etc.，this paper illuminates mechanism of deformation at the intake of flood-discharge tunnel No.2. Meanwhile，the mode of deformation and destruction of this kind of anti-inclined slope，which is composed of a series of soft rock layers in its lower part and hard rock layers in its upper part，is the compressed-toppling going with sliding. It is demonstrated that the deformation of this slope is always initiated by the non-uniform compression of the soft rock layer，leading to toppling of the upper hard rock layer；finally，the tensile fracture of sliding appears along discontinuities paralleling with slope. Besides，two-dimensional finite element calculation is used to analyze the regularities of stress field and displacement during the excavation and to demonstrate the mechanism of this deformation.

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DYNAMIC STABILITY ANALYSIS OF HIGH EARTH-ROCKFILL DAM ON THICK MORAINE COVER FOUNDATION

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2005, 24 (12): 2041-2041 doi:

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To build high earth-rockfill dam on thick moraine cover foundation in high earthquake intensity region will face many new problems such as dynamic stability，dam foundation liquefaction etc. As an example，three-dimensional dynamic consolidation FEM is employed to analyze the reaction of high earth-rock fill dam with clay core and cat-off wall. The dynamic stability is researched. An equivalent quasi-elastoplastic constitutive model which can express nonlinear viscid and un-recoverable deformation of soil is employed in the new dynamic consolidation FEM，while dynamic pore water pressure model is abandoned. The generation，diffusion and scatter of dynamic pore water pressure in a complete earthquake process are tracked. It is a real coupling of dynamic seepage and dynamic reaction. The calculation results show that the static stress and displacement of the dam on thick moraine cover foundation are bigger；the dynamic stress，displacement and acceleration are smaller；the ratio of pore water pressure in the dam base is smaller than the dam on rock foundation. The dam is safe.

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RESEARCH OF MULTI-CHANNEL MICROSEISMIC MONITORING SYSTEM AND ITS APPLICATION TO FANKOU LEAD-ZINC MINE

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2005, 24 (12): 2048-2048 doi:

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Microseismic monitoring technique is a main means of ground pressure monitoring for deep mines. The occurrence，the ground pressure characteristics and hazards of deep orebody at Fankou mine are summarized briefly. The composition and performance of 16-channel microseismic monitoring system established recently in the mine and the monitoring area are introduced in detail. Optimal analysis of layout of sensors gives the optimized results of sensors positions presented through an isogram of the source location. Source location errors are tested through artificial blasts. The test data and the monitoring source location figure are presented. The tested results are compared with those of theoretical results determined by the monitoring system. The compared results show a smaller locating error of less than 5 meters within sensors array and the perfect source locating performance of the system. Large blasts aftershocks in deep mining area are monitored by this system. The results show that all monitored aftershocks occur in a few minutes after blasts，which means rock mass surrounding the mining area has a good stability condition at present.

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EXPERIMENTAL STUDIES ON TEMPERATURE DEPENDENT PROPERTIES OF CREEP OF ROCK SALT

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2005, 24 (12): 2054-2054 doi:

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Experimental studies are made on the creep properties of rock salt after undergoing different high temperatures；the effect of stress level and temperature on creep of rock salt is analyzed. Through the creep characteristic curves and parameters，the steady state creep strain rate constitutive equation of rock salt is obtained by regression. The results indicate that the effects of deviatoric stress and temperature on the steady state creep strain rate of rock salt are obvious. The steady state creep strain rate is a power function of deviatoric stress and exponential function of temperature and energy. Based on the relation of creep modulus and creep time for rock salt，the creep damage evolution and creep damage constitutive equation are established.

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A NEW GLOBAL OPTIMIZATION ALGORITHM FOR ANALYSIS OF NON-CIRCULAR SLIP SURFACE

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2005, 24 (12): 2060-2060 doi:

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A new approach based on the method of slices to analyze the stability of slopes with non-circular slip surface is presented. Generally，when a sliding body is discretized to slices，the slices¢ nodes represent the slip surface. So the basic approach of this algorithm is to move the nodes randomly and uses a non-numerical method，such as simulated annealing(SA) to induct the current surface to the most potential critical slip surface. There are several merits of this method：it doesn¢t need to configure searching domains；it can figure out the shape of slip surfaces naturally even under the geometrically and geologically complicated realistic situation without presuming the surface shape previously and it performs with high efficiency since each time the change focuses on only one node. Several test problems are listed and demonstrate that this algorithm can pick out the global critical surface. It also testifies that the shape of potential failure surface can be circular arc，straight lines，or combination of them. Finally，more effective searching strategies are discussed.

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ENRICHED MESHLESS MANIFOLD METHOD

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2005, 24 (12): 2065-2065 doi:

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In meshless manifold method，finite cover technology is employed. The mathematical finite cover approximation theory is used to model cracks that lead to displacement discontinuity. The discontinuity is treated mathematically instead of empirically by the existing methods such as：(1) the diffraction method；(2) the transparency method；and (3) the see-through method. One cover of a node is divided into two irregular sub-covers when the meshless manifold method is used to model the discontinuity. However the method sometimes causes numerical errors at the tip of a crack. To improve the precision of the meshless manifold method，the enriched methods are introduced. The enrichment of solution of the meshless manifold method near the tip of a linear- elastic crack is achieved by expanding the basis functions with special functions. The validity and accuracy of the enriched meshless manifold method are illustrated by numerical examples.

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INTERACTIONAL MECHANICAL CHARACTERISTICS OF ROCK-SUBSTRATE-ROOT SYSTEM

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2005, 24 (12): 2074-2074 doi:

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Substrate-root system complex (SRSC) is the main functional part of the eco-engineering for rock slope protection. It is important content for eco-engineering mechanism exploration to evaluate the interactional characteristics of SRSC quantification ally by mechanics. This paper discusses the interactional mechanics characteristics of SRSC from experiment. The shear and tensile strength of SRSC and the shear strength between complex and rock are both studied；the relationship of shear and tensile strength and factors of root amount and water content are also researched；the effects of time scale is discussed in the end. The results show that the shear resistance between SRSC and rock consists of friction and biotic force. The shear strength decreases with water content increasing while reduces with root amount increasing. They represent logarithm functional relationship. Water content influences on both friction and biotic force，but the latter is the main influenced aspect. The complex has tensile strength due to root system. The tensile strength increases with root amount enhancing while decreases with water content increasing. They represent relatively notable functional relationship. The reinforced effect and friction enhance with root amount increasing，whereas reduce with water content increasing. The relationship between shear strength(τ) and vertical pressure(s) accords to Coulomb law. Besides general physical significance of shear strength indexes，j and c include the effect of root system. In the case of the same water content and vertical pressure，shear strength and root amount represent exponential functional relationship. The values of j and c increase with the total amount of root system enhancing. So the shear strength of complex will be elevated markedly. In the case of the same root amount and vertical pressure，shear strength and water content represent power functional relationship. The values of j and c decrease with water content enhancing. So the shear strength of complex will decline. The interactional mechanical characteristics of the rock-substrate-root system exhibit a significant time scale effect with plant developing，and it gets stable after 5 months of seeding when Cynodon dactylon is concerned. It is an essential support to renew the theory of the eco-engineering for rock slope protection and to apply it.

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SEISMIC RESPONSE ANALYSIS OF SEASONALLY FROZEN GROUND OF ZHANGYE AREA

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2005, 24 (12): 2082-2082 doi:

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A test site in a seasonally frozen region in Zhangye City，Gansu Province，China is taken to investigate the ground motion features in different seasons. Micro-tremors are measured and analyzed. Undisturbed samples are taken from the site and triaxial dynamic tests are performed in their unfrozen and frozen states in order to obtain the dynamic parameters，such as shear modulus ratio and damping ratio of the soils. The input for the ground motion analysis，such as boundary conditions，seismic records and soil parameters are discussed. Together with the results from previous seismic risk analysis，the parameters are input into a one-dimensional shear beam model so that ground motion parameters are calculated for the site in seasons with and without frozen layer. Furthermore，different depths of the frozen layer are assumed and peak ground motion parameters and response spectra are calculated. Calculation shows that the seasonal existence of frozen layer can restrain the strong motion to some extent，therefore，the frozen layer has positive effect on the site subjected to seismicity，and the effect increases with the increase of frozen depth；at the same time，the predominant period of the ground decreases with the increase of the depth of frozen layer. The results obtained can also be applied to other regions with similar ground conditions.

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PHYSICAL MODEL STUDIES ON STABILITY OF ZHAOSHULING LANDSLIDE IN AREA OF THREE GORGES RESERVOIR

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2005, 24 (12): 2089-2089 doi:

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Three small-scale 2D physical model experiments were conducted on a model table with the goals of investigating the potential deformation features and failure mechanics of a landslide in the Three Gorges Reservoir under conditions of reservoir impounding，water level fluctuation，building load on the surface of slope and potential seismicity，and evaluating its whole stabilities in the future. Dial gauges，gridding lines and digital camera were used to monitor quantitatively and write down qualitatively the deformations and displacements of the models. High/low unit weight model materials were used to simulate self-weight of sliding mass above groundwater level and sliding mass below groundwater level respectively. According to seepage force theory and similarity laws，the resultant hydrodynamic force was obtained by concentrated loading. The loading owing to the buildings was simulated by some Barite-gypsum blocks placed on the surface of the model. The seismic loading was simulated by raising the inclined plane on which the landslide model was placed. The research results show the slope on which a seven-floor building locates was stable when the water level is 145 m or 175 m，or under a rapid drawdown condition from 175 m to 145 m. While the intensity of earthquake is greater than a certain value，it must be of instability；and its stability must be the worst when the water level in the reservoir drawdown rapidly from 175 m to 145 m；and its stability must be better under condition of the water level 175 m than that of the water level 145 m. If the landslide would happen，the failure mechanism must be pull-type.

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APPLICATION OF PRESTRESSED GROUND ANCHORS IN RECTIFICATION AND REINFORCEMENT OF FOUNDATION

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2005, 24 (12): 2096-2096 doi:

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Prestressed ground anchor has been used widely in all kinds of geotechnical engineering reinforcement such as hydropower，highway，railway，mine and city planning etc.，and remarkable economic and society benefits have been achieved with ground anchor reinforcement in these fields. Now ground anchors have become the main method in these engineering reinforcements. But，there is hardly literature report and engineering practice about prestressed anchor cable used in rectification of foundation. The west gate of GuoHua Garden in Luoyang city is mainly a steel structure，with total weight of 600 kN. The soil conditions underlying the bases are fills in the range of 7–8 m in the depth，which are mainly composed of clayey silt and a little building waste. Non-uniform settlement of the ground has appeared since the west gate of the garden was built because of not compacted of foundation soil during the ground treatment. Prestressed ground anchors have been used successfully in the rectification and reinforcement. The practice shows that prestressed anchor cable technique can play unique advantage in rectification of foundation，offer reference for similar engineering，and find more application range.

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MINING-INDUCED INFLUENCES ON STABILITY OF FLOOR HAULAGE ROADWAY IN TECTONIC STRESS FIELD

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2005, 24 (12): 2101-2101 doi:

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A three-dimensional computational model is applied to analyze the stability of rock-bolting and shotcreting support in the floor haulage roadway. The mining sequence effects in different working faces on stability of floor haulage roadway in high tectonic stress field in Fangezhuang Coal Mine are discussed. The main factor causing destruction of roadway in tectonic stress field is found to be the high tensile strain, which appears after the coal seam above haulage roadway is mined. In addition，the key principle of laying floor haulage roadway in high-level stress field is proposed in this paper to keep pillars above the haulage roadway unmined. In this way, the obvious influences of high abutment pressure induced by coal mining can be alleviated or avoided for the roadway is at nearly equal pressure on both directions. It is proved by engineering practices in Fangezhuang Coal Mine of Kailuan Group Limited Liability Company that the key principle is capable of reducing maintenance of haulage roadway in service and maintaining the stability of the roadway.

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STUDY ON CONTROLLING MECHANISM OF SURROUNDING ROCKS OF GOB-SIDE ENTRY WITH COMBINATION OF ROADSIDE REINFORCED CABLE SUPPORTING AND ROADWAY BOLT SUPPORTING，AND ITS APPLICATION

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2005, 24 (12): 2107-2107 doi:

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The gob-side entry retaining technology is widely used in the thin or medium thick coal seam，but rarely employed in the over-3-meter mining-height working face. The reasons mainly lie in the following two aspects: firstly，the traditional mechanical model for the gob-side entry is unsatisfactory and secondly，the roadway and roadside supports are unreasonably placed. By taking into consideration of the bearing capacity of rocks，this paper presents a reinforced active supporting technique，consisting of the cable-reinforced roadside supporting technique and the roadway bolt-supporting technique. For practical purpose，a new mechanical model is established，taking into account both the roadside coal bearing capacity and the reinforcing effects of the roadside cable-support. The improved supporting mechanism with the combination of the roadway bolt-supporting technology and the reinforced roadside cable supporting technology is analyzed. The results are applied successfully to the design and engineering practice in the airway of the high working face No. 3625 of Zhuzhuang Mine，Huaibei. The research result provides a theoretical basis and some useful experience for the gob-side entry retaining work of large mining-height working faces.

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FIELD TESTING STUDY ON LOAD DISTRIBUTION MECHANISM OF PRESTRESSED ANCHORAGE CABLE

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2005, 24 (12): 2113-2113 doi:

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Based on field testing results and numerical simulation of prestressed anchor cable of tunnel anchorage system of suspension bridge，the ultimate anti-pulling capacity and failure mode affected by anchor-length，free- length，grouting quality and interface mode between grout-cable and rock mass are analyzed. Stress distribution modality in rock mass and root effect are also introduced. And the concept of safety storage coefficient is put forward. It indicates that the increase of ultimate anti-pulling capacity increase principally depends on synthetical functions of the variables mentioned above. Free-length has key effect on effectively transferring and dispersing stress to wall rock. The failure mode of anchor cable is controlled by free and anchor length. The contribution value and occasion of anchor cable are determined by its free-length and initial stress.

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SELECTING ARCH SHAPE OF LARGE CAVERNS UNDER HIGH IN-SITU STRESS BY METHOD OF GRAY CONDITION CRITERION

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2005, 24 (12): 2119-2119 doi:

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Based on rock geological data of a large cavern under high in-situ stress，the effects of three arch shapes，single center arch and three-center arch and elliptical arch，of large caverns under high in-situ stress on stress effect in rockmass of arch are analyzed by the elastoplastic finite element；The results reveal that this effect is very obvious，and some stress concentration factor reaches 3.33；whichever arch shapes are adopted，stress intensity neighborhood of arch seat is unavoidable. Gray condition criterion is developed with plastic region and stress concentration factor；and each gray condition value is calculated. According to gray condition value，by synthetically judging，no matter what in-situ stress side pressure coefficient is，the elliptical arch is the best with the three-center arch the second.

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STUDY ON LANDSLIDE EROSION BY DISCRETE ELEMENT METHOD

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2005, 24 (12): 2124-2124 doi:

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The principle of discrete element analysis method is introduced and applied to simulate a real case of the No.2 landslide on Tong—Wang highway. The geological model is built up with consideration of vertical joints and strata planes as discrete discontinuities in loess. Then the landslide body is meshed into 297 units by the two sets of structural planes，while the units under the sliding bed which is bed rock are treated as fixed. Furthermore，discrete element method is used to analyze the typical characters of the erosion evolution process of landslide. The average velocity，average acceleration，resultant forces and moment in back，middle and front portion of the landslide are calculated. The results suggest that the evolution process of landslide can be divided into five stages，i. e. initial breaking stage，extensive accelerating stage，high speed moving stage，bumping deceleration stage and slow braking stage.

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ERRORS STUDY ON Q-s CURVE OF PILE SIMULATED BY HIGH STRAIN DYNAMIC TESTING METHOD

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2005, 24 (12): 2129-2129 doi:

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Based on the test results of pressed piles by static load test and high strain dynamic test in an engineering test，as well as the analysis of mechanical behaviors of pile shaft material and developing behaviors of soil resistance and the load transfer behavior，an analysis of errors of Q-s curve simulated by high strain dynamic testing method is made. The settlement of pile calculated by high strain dynamic testing method is higher than that of pile tested by load test when load is smaller；and it is bigger than the result of load test when load is higher. These errors are relative with the mathematical model about pile shaft concrete and soil resistance in high strain testing. Concrete is thought as elastic body in high strain testing，but actually it is nonlinear，this brings about some errors in Q-s curve of pile simulated by high strain dynamic testing method. The model of static soil resistance in high strain testing，which is thought as elasto plastic model，is not the same as the actual developing behaviors of soil resistance；and the settlement of pile in high strain testing is smaller than that in static loading test；these are major factors which bring about errors in Q-s curve of pile simulated by high strain dynamic testing method. These factors should be considered when the Q-s curve is simulated by high strain dynamic testing method.

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MODEL TESTING RESEARCH ON DEFORMATION AND FRACTURE MECHANISM OF LANDSLIDE AND ITS HARNESSING ENGINEERING

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2005, 24 (12): 2136-2136 doi:

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To analyze the deformation and fracture mechanism and the harness effects of the landslide， by large scale model testing，the authors select several different materials to simulate corresponding rocks and structure for the model of the landslide with a model scale of 1∶200. The model has size of 240 cm×120 cm×20 cm. Based on the geomechanical model test，the deformation and fracture course of the landslide of four different states：natural state，excavating state and two different reinforcement state，are simulated；and the displacement of landslide，the stress state of anti-slide pile and bolt of different testing procedures are studied. On the basis of the testing results，the deformation and fracture mechanism of the landslide are analyzed；and harnessing effects of two different reinforcement designs are compared and optimized. The study result provides a scientific basis for mechanism study and treatment of the landslide.

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EXPERIMENTAL STUDY ON TIME-DEPENDENT DEFORMATION OF SOFT SOIL

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2005, 24 (12): 2142-2142 doi:

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Time-dependence is one of the most important deformation behaviors of soft soil. It brings on post-construction settlement of soft soil engineering. For the need of practical engineering，a series of laboratory tests were done with undisturbed samples and disturbed samples respectively. And the deformation mechanism of soft soil was investigated，including stress-strain behavior，consolidation effect，secondary consolidation characteristics，creep effect，and so on. Based on the results，some special properties are systematically analyzed： (1) the influence of initial consolidation on stress-strain curve；(2) the relationship between secondary consolidation coefficient and consolidation pressure，as well as the influence of stress history on secondary consolidation coefficient；(3) the relationship between secondary consolidation coefficient and compression index；(4) the deformation characteristics of drained shear creep and undrained shear creep；(5) influencing factors on creep and technology of decreasing creep deformation. The study results show that time-dependent deformation of soft soil issues from the coupling effect of consolidation characteristics and creep characteristics. The deformation course of soft soil is actually the process of consolidation and creep concurrently. The ratios of two deformations to total deformation depend on many factors，among which stress level and drainage condition are the most important.

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STUDY ON MEASUREMENTS OF EARTH PRESSURE AND WATER-SOIL PRESSURE ACTING ON RETAINING WALL

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2005, 24 (12): 2149-2149 doi:

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Using homemade test box，the study on measurements of the earth pressure and the water-soil pressure acting on rigid retaining wall in modes of active wall translation，rotation around its top and rotation around its bottom，is performed. The measured results show that the value and the position of action point of the earth pressure and that of the water-soil pressure vary with different wall movement modes，so the interval estimation of the earth pressure and the water-soil pressure is presented.

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RESEARCH ON IN-SITU TEST OF MECHANICAL BEHAVIORS OF LINING IN NEW-STYLE RAILWAY TUNNEL PORTAL

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2005, 24 (12): 2155-2155 doi:

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Railway tunnel portal is always designed according to the standard drawing with experience. Research on new-style tunnel portal is necessary. Besides a new-style tunnel portal should have aesthetic effect and be beneficial to protect environment，it should be ensured security of the structure. Surrounding rock pressure and mechanical behaviors of lining in the new-style tunnel portal had been tested in-situ. The distributed characters of surrounding rock pressure and mechanical behaviors of lining are discussed，by comparing the test results with model experiment and finite element analysis results. The results show that the surrounding rock pressure and internal force of lining increase from the tunnel entrance to inside in the bamboo-truncating tunnel portal. The value increases with the depth of cover. The pressure of surrounding rock is maximal at the invert arch. And the lining is in complicated three-dimensional mechanical state. There are not only circumferential axial force and bending moment but also longitudinal axial force and bending moment. The mechanical behaviors of lining are similar to those of shell structure. So it is reasonable to design lining for the tunnel portal as a shell structure.

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TESTING STUDY ON REINFORCING SOFT FOUNDATION OF HIGHWAY BRIDGE-HEAD BY VACUUM COMBINED WITH SURCHARGE PRELOADING

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2005, 24 (12): 2160-2160 doi:

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The observation results of the Jialichen bridge-head experiment site such as pore water pressure，settlement of soil at various depths，surface settlement，and horizontal displacement are analyzed. The results show that the combined excessive pore water pressure in the soft ground is relatively small，usually less than zero，which is produced by negative excessive pore water pressure and positive excessive pore water pressure through the process of vacuum combined with surcharge preloading，so that it is advantageous for rapid embankment construction. The results also show that the settlement can be eliminated greatly；and settlement after completion of construction is less than 100 mm，meeting the requirement of bridge-head soft ground. The soil horizontal displacement is little in the influence area 20 m away from the improvement area border. The effect of soil improvement is evaluated；and the result shows that the effective influence depth of vacuum preloading can be deeper than 10 m. The improvement effect is checked；and the results show that the strength of soil in the improvement area is improved obviously；and the soft foundation treated by vacuum combined with surcharge preloading is very effective. Combined with the observation results，the mechanism of vacuum combined with surcharge preloading is analyzed；and the superimposed stress distribution diagram is given.

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CONSOLIDATION STATE OF SOFT SOIL DIFFERENTIATED BY STATIC CONE SOUNDING

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2005, 24 (12): 2166-2166 doi:

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The consolidation state of soft soil is of significance for evaluation of deformation and strength of foundation soil. The consolidation state of soft soil in the coastal area of Fujian Province is differentiated by static cone sounding. For the normal consolidation state，the fitting beeline of static cone sounding of soft soil between cone resistance and test depth intersects the x-coordinate at the origin approximately；for the overconsolidation state，intersects the positive x coordinate；and for the underconsolidation state，intersects the negative x coordinate. The consolidation state of soft soil can be differentiated by the intercept of the line. The consolidation state of soft soil，tested by in-situ static cone sounding，fits the actual condition of soft soil；and the method can be used for the evaluation of the consolidation state of soft soil.

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FLEM FOR GROUND SUBSIDENCE CALCULATION AND DATA FIELD EXPRESSION MODEL BASED ON GIS

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2005, 24 (12): 2170-2170 doi:

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GIS building up by geoscience digitalization and visualization is widely used in geotechnical engineering. Ground subsidence due to underground tunnel excavation and mining is a kind of drastic engineering disaster. It is valuable to conduct real-time prediction and evaluation of ground subsidence and its damage based on GIS，GPS，and RS technology. This paper provides a semi-analytic method，finite layer element method (FLEM)，which is used in underground mining subsidence calculation and geological body stress analysis and gives out the displacement pattern，the strain matrix，the elastic matrix，the stiffness matrix of the element and the stress matrix of this method. It also presents the data model for this method integrated with GIS and data organization approach. Meanwhile，the multilingual integrated pattern and data visualization method based on GIS subsidence damage evaluation system are proposed；and the reliability of the method through the application of engineering examples is verified.

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NUMERICAL SIMULATION OF STRATUM DEFORMATION ABOVE OVERLAPPING METRO TUNNEL

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2005, 24 (12): 2176-2176 doi:

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Taking the overlapping tunnel of Shenzhen Metro Phase I project for example，the FLAC3D (fast Lagrangian analysis of continua)codes was adopted to model the stratum 3D deformation regularity caused by four-step shallow tunnel construction method(STCM). By comparing with the in-situ monitor data of the test section，the value of stratum deformation caused by tunnel excavation or seepage of groundwater was obtained，and the environment control standard of general stratum is differentiated from that of aqueous sand stratum. According to the standard，the maximum value of ground settlement of general soft stratum of Shenzhen Metro is 60 mm and that of aqueous sand stratum is 120 mm. For some position with high standard of ground settlement control requirement，second reinforcement measures are taken to decrease stratum deformation，such as ground vertical jet grouting reinforcement which costs more than the general reinforcement measures. The technique has been applied successfully in Shenzhen Metro Phase I project. The research result will provide reference for controlling the construction environment of the construction of Shenzhen Metro and the project with the similar stratum. It will also offer theoretical reference for the application of shallow tunnel construction method(STCM) to aqueous soft sand stratum.

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STUDY ON EXCAVATION PARAMETERS FOR HIGH ROCK SLOPE OF SCATTERED STRUCTURE

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2005, 24 (12): 2183-2183 doi:

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The parameters of rock slope excavation are mostly selected by analogy method of engineering geology at present. However，the selected parameters are chiefly determined by experience of the user and comparability between the newly designed slope and the slopes ranked in reference table，the theory is lack of reliability，and the newly-designed slope is over-safe or under-safe. Therefore，with respect to the rock slope of scattered structure，the slope excavation process is modeled by numerical simulation；and the variation of displacement and stress for various sidestep ratio，height and platform width are compared，the stability and economy of the slope excavation are fully considered；and the optimization parameters of slope excavation are proposed. The research will provide theoretical basis for slope excavation.

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NUMERICAL MODELING ANALYSIS OF SETTLEMENTS OF HIGH FILL FOUNDATION FOR JIUZAI—HUANGLONG AIRPORT

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2005, 24 (12): 2188-2188 doi:

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Jiuzai—Huanglong airport is located on the eastward slope of Zhangla basin in Songpan County in the northwest of Sichuan. By using FLAC3D program to simulate real construction process，the settlement of the high fill foundation especially differential settlement，which has the most powerful influence on Jiuzai-Huanglong airport is quantitatively analyzed and evaluated. The results indicate：(1) The calculation results coincide with the monitoring results. (2) The settlement center lies in the place of slope shoulder with the maximum settlement amounting to 2.8 m；and the settlement gradually decreases on the runway and the base of slope. (3) The total after-construction settlements have close relations with thickness of the fill and soft layer，i.e. the bigger settlement often presents at the places with thicker fill or thicker fill and soft layer.

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OBJECT-ORIENTED DEEP-SEARCHING GENETIC ALGORITHM AND ITS APPLICATIONS TO ENGINEERING(II)—ALGORITHM VALIDATION AND ITS APPLICATIONS TO ENGINEERING

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2005, 24 (12): 2194-2194 doi:

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The deep-searching strategy of the object-oriented genetic algorithm is validated by comparing its optimum results with the corresponding results obtained by the nonlinear constrained programming tools“constr”of Matlab through thousands of optimum calculation examples. The results indicate that the deep-searching strategy of the genetic algorithm is valid；and it can get the best optimum result of the problem to the most extent. The programs of optimizing the landslide support structure and deep foundation pit support structure are applied to many practical engineering to check up their performance of optimizing the structure and selecting the reasonable structure type. The result indicates that the single program can well optimize the corresponding structure；and the combined programs can help engineers to select reasonable type of support structure.