Select

STUDY ON YIELD SURFACES IN GENERALIZED PLASTIC MECHANICS

Duan Jianli，Chen Yuyao，Zheng Yingren

2002, 21 (05): 617-620 doi:

[PDF] 665 KB (750)

[HTML]

+

Show Abstract

The generalized plastic mechanics developed from the traditional plastic mechanics can reflect the real deformation mechanism of geomaterials. According to the generalized plastic mechanics，the constitutive model is composed of three plastic potential surfaces and three corresponding yield surfaces. The relationship between the yield surface and the plastic potential surface is discussed systematically，and the basic characters of yield surface，especially of volume yield surface that can calculate dilatant volume strain and shear yield surface in stress Lode angle direction，are also discussed.

Select

STUDY ON DAMAGE CONSTITUTIVE RELATION OF #br# THREE-DIMENSIONAL STRATIFIED COMPOSITE ROCK #br#

Liu Li，Qiu Xiande，Yan Zongling

2002, 21 (05): 621-625 doi:

[PDF] 1359 KB (765)

[HTML]

+

Show Abstract

The damage structure and constitutive relation of common bedded composite rock are researched. The micrcoscopic study of rock by SEM shows the characteristic of their microstructure and micropore. The damage constitutive equations and damage evolution equation in three dimensional nonlinear state are derived under different conditions，such as unequal biaxial stress，different effective stress，different mechanical parameters and damage evolution processes for every stratification. The study results are well testified by experiments.

Select

CONSTITUTIVE MODEL OF ROCK UNDER TRIAXIAL LOADING AND UNLOADING

Zhao Mingjie1，Xu Xibin1，Xu Rong2

2002, 21 (05): 626-631

[PDF] 944 KB (0)

+

Show Abstract

Based on the linear elastic fracture mechanics theory，a constitutive model of rock with microcracks under triaxial loading and unloading is developed. In the developed model，rock is assumed to be made of homogeneous，isotropic，linear elastic material containing a lot of random“ellipse-shaped” microcracks. The deformation of rock is decomposed of the deformations of rock matrix and microcracks. The calculation formulae of microcrack deformation are given. In order to check the proposed theoretical model，the testing study is made for gypsum model. The testing results are well consistent with the theoretical predictions.

Select

RHEOLOGIC CONSTITUTIVE RELATIONSHIP OF ROCKS #br# AND A MODIFICAL MODEL #br#

Cao Shugang，Bian Jin，Li Peng

2002, 21 (05): 632-634 doi:

[PDF] 390 KB (769)

[HTML]

+

Show Abstract

The adhesion factors in adhesion model of rocks are changed with the non-linear relations through analyzing the mechanical experiment curves of rocks. Therefore，a new ahead model of rocks is proposed through the change：H-(H‖N)-(M‖St.V)，where M is a modified model about the I. Newton’s model. The model is of the feature of the non-linear accelerative creep of rocks.

Select

CHARACTERISTICS OF BIFURCATION，CHAOS AND SELF-ORGANIZATION OF EVOLUTION OF MICRO-CRACKS IN ROCK

Yin Guangzhi，Dai Gaofei，Wan ling，Zhang Dongming，Wei Zuoan

2002, 21 (05): 635-639

[PDF] 963 KB (0)

+

Show Abstract

On the basis of test results of micro-fracturing process and evolution of micro-cracks in rock under uniaxial compression，the theory of bifurcation，chaos and self-organization in the nonlinear dynamics are applied in the research on micro-crack property. The results show that the evolution of micro-cracks could be described by the Logistic equation，so that the evolution of micro-cracks of rock is of the characteristics of bifurcation and chaos. Meanwhile，the relationship between length and number of micro-cracks at each stress level is studied. The results show that the evolution of micro-cracks follows power law，and the system of micro-cracks in rock is of the feature of self-organization.

Select

ANALYTICAL STUDY ON FRACTURE OF JOINTED ROCK MASS UNDER INTERNAL PRESSURES

Wang Cheng1，Deng Anfu2

2002, 21 (05): 640-643

[PDF] 539 KB (0)

+

Show Abstract

There are often water or soft in joints of rock masses. It is an important problem in the geotechnical engineering that the internal pressure leads to the fracture of joints. The problem is simplified as one of a joint under I mode internal pressure in the finite rock mass，and solved by the near-joint-line method based on the failure criterion of rock bridge material and equilibrium equations. The relationship between the internal pressure and cracked region length along the joint line is obtained.

Select

SEEPAGE EQUATION OF COALBED GAS IN GEOPHYSICAL FIELD

Wang Hongtu1，Du Yungui1，Xian Xuefu1，Luo Pingya2

2002, 21 (05): 644-646

[PDF] 302 KB (0)

+

Show Abstract

According to the seepage properties of coalbed gas affected by in-situ stress field，geothermal tempe- rature field and geo-electric field，the coalbed gas permeability is investigated and obtained in geophysical field. The results indicate that coalbed gas permeability is related to the effect stress with a negative index，to the geothermal temperature T with a power function and proportional to the geo-electric field strength E. By establishing coalbed gas flow equation，coalbed gas flow continuity equation，coalbed state equation and coalbed gas content，the coalbed gas seepage equation is gotten in geophysical field. The coalbed gas seepage equation contains common influence of in-situ stress field，geothermal temperature field and geo-electric field on coalbed gas seepage properties. As a new theory，the coalbed gas seepage equation will be as a theoretic basis to discuss coalbed gas flow law in geophysical field under certain conditions.

Select

RESEARCH ON THE MECHANISM AND PREDICTION OF DELAY OUTBURST OF COAL AND GAS

Liu Baoxian，Xian Xuefu，Jiang Deyi

2002, 21 (05): 647-650 doi:

[PDF] 606 KB (676)

[HTML]

+

Show Abstract

The menace of delay outburst of coal and gas is very serious. The mechanism of delay outburst of coal and gas is studied with nonlinear theory，catastrophe theory，and some useful conclusions are drawn. It is concluded that the delay time of coal and gas delay outburst is obtained by the combination of geostresses，gas inside the coal，physico-mechanical characteristics of coal and external action，e.g. explosion. According to above research，the way to predict delay outburst of coal and gas is discussed.

Select

SITE TESTING AND MONITORING OF INDUCED STRESS FIELD IN SURROUNDING ROCKS OF UNDERGROUND ENGINEERING

Jin Xiaoguang 1，Wang Lansheng 2，Li Xiaohong 1

2002, 21 (05): 651-653 doi:

[PDF] 459 KB (1009)

[HTML]

+

Show Abstract

Combined with the underground engineering practice in high geo-stress area，the stress restitution testing and lag monitoring are made to determine the induced stress field of surrounding rocks for underground engineering. The correctness of testing results is checked by elastic mechanics theory and individual hole stress rescission testing，and satisfying results are obtained.

Select

STUDY ON THE COMPOSED ROCK BEAM THEORY OF STRATA MOVEMENT AND ITS APPLICATION

Liang Yunpei，Sun Dongling

2002, 21 (05): 654-657 doi:

[PDF] 569 KB (821)

[HTML]

+

Show Abstract

The composed rock beam model for movement of overlying strata in stope is proposed. The key stratum of strata movement，the strata combinations of ground control and the separated bed are unified in this model，and a unitive criterion for determining the key stratum，the strata combinations and the separated bed is founded with an example analyzed. The applications of the composed rock beam model in ground control，surface subsidence control and gas prevention in coalmine are studied deeply. This model provides a unified idea and method for study of pressure in longwall mining and strata movement.

Select

EVOLUTIONARY NEURAL NETWORK MODEL ON PREDICATION OF LOOSEN ZONE AROUND ROADWAY

Gao Wei，Zheng Yingren

2002, 21 (05): 658-661 doi:

[PDF] 565 KB (890)

[HTML]

+

Show Abstract

In view of the shortcomings of the simple genetic algorithm(SGA)，such as slow convergence and premature character，a new algorithm with fast convergence，good performance is proposed by improving the encoding，generation of initial population and genetic operators. And the new algorithm is tested and verified by experiments. An evolutionary neural network(ENN) model is constructed by using this algorithm to evolve the architecture and parameters of neural network. At last，the prediction on the thickness of the loosen zone around roadway is made with this ENN model，and the results show that the convergence and the forecasting capability are all good.

Select

PHYSICAL SIMULATION ANALYSIS ON CONSTRUCTION MECHANICS BEHAVIOR OF ROAD TUNNEL

Jiang Shuping1，Huang Lunhai1，Song Congjun2

2002, 21 (05): 662-666 doi:

[PDF] 1537 KB (748)

[HTML]

+

Show Abstract

Through large-span physical simulation experiment for a road tunnel engineering under different surrounding rock mass conditions，the analysis is carried out on displacement and stability of surrounding rock mass of road tunnel. Then the construction of road tunnel is guided by this analysis.

Select

STUDY ON DEFORMATION CHARACTER OF SURROUNDING ROCK MASSES AND NUMERICAL MODELING OF XISHANPING TUNNEL THROUGH COAL AND WORKING OUT AREA

Li Xiaohong，Jin Xiaoguang，Lu Yiyu，Kang Yong，Lei Xiangyang

2002, 21 (05): 667-670 doi:

[PDF] 1415 KB (847)

[HTML]

+

Show Abstract

According to the NATM construction monitoring practice of Xishanping tunnel of Yuhe-freeway (from Chongqing to Hechuan)，the deformation character of surrounding rock masses of the tunnel through coal and working out area is analysed，The dynamic construction state is modeled by FEM，and the calculation result is verified with the displacement monitoring data.

Select

RESEARCH ON OBJECT RELIABILITY INDEX AND PARTIAL COEFFICIENT OF BOLT-SHOTCRETE LINING FOR TUNNEL

Xu Jun，Zheng Yingren，Liu Dongsheng

2002, 21 (05): 671-674

[PDF] 306 KB (0)

+

Show Abstract

Underground support engineering is considered as an uncertain system. Response surface FEM is used to calculate the expected values and its variance of shotcrete’s stress，and Kuper failure criterion is employed as limit state function. The reliability of blot-shotcrete support is analyzed by the reliability theory，and the object reliability index is analyzed by the “calibration method”. Finally，the partial coefficients of the design formula are analyzed by the “fractile method”.

Select

MONITORING DURING THE ACCESS CONSTRUCTION OF YANGPENG RIGHT TUNNEL

Xu Linsheng 1，Sun Jun 2，Jiang Shuping 3

2002, 21 (05): 675-678

[PDF] 971 KB (0)

+

Show Abstract

The site monitoring was made during the access construction of Yangpeng right tunnel with CRD excavation method. By means of the monitoring and detailed analysis for each construction stage，feedback controlling design is realized and the construction is controlled.

Select

OPTIMUM ANALYSIS ON THE CONSTRUCTION PROCESS FOR JOINT ARCH TUNNELS IN PARTIAL PRESSURE

Zhou Yuhong1，Zhao Yanming1，Cheng Chongguo2

2002, 21 (05): 679-683

[PDF] 1681 KB (0)

+

Show Abstract

The construction process of joint arch tunnels of Yuan-Mo expressway is simulated with FEM program ANSYS V5. 61. The stress state of surrounding rocks，ground settlement and internal forces of tunnel support structure during each period of construction are obtained by 2D computation. The calculated results are analyzed and compared with the measured data in site. The analysis results provide a scientific basis and technical guidance for the construction optimization of joint arch tunnels in partial pressure.

Select

ANALYSIS ON SAFETY FACTOR OF ANCHORED ROCK MASSES

Peng Wenxuan 1，Liu Dongyan 1，Yang Jianguo 2

2002, 21 (05): 684-687 doi:

[PDF] 740 KB (677)

[HTML]

+

Show Abstract

Constitutive model is established to take the slide surface，tear or yield of the layer into account comprehensively. With this model，the safety factor of anchored rock masses is determined against integrate slide and compared with that obtained by limit equilibrium theory.

Select

DISASTER ANALYSIS ON SHILIUSHUBAO LANDSLIDE MASS IN THE HUANGLASHI LANDSLIDE GROUP IN THREEGORGES OF YANGTZE RIVER

Yang Xuetang 1，2，Zhang Yongxing1

2002, 21 (05): 688-692

[PDF] 630 KB (0)

+

Show Abstract

The sliding velocity，sliding distance and the wave due to landslides are calculated for Shiliushubao landslide mass of the Huanglashi landslides group in Three Gorges of Yangtze River. And analyses are made on the calamity of blocking on Yangtze River and the calamity to the circumstance of the towns along the river and the security of Three Gorges Dam during its construction and operating. Based on the analyses，it is believed that the landslides may block shipping way when the water level is low. The wave would not influence seriously the Three Gorges Dam，while landslide will harm the Badong and Guandu County.

Select

COMPREHENSIVE TREATMENT AND STABILITY ANALYSIS FOR A SLOPE

Yan Changwu1，Deng Anfu1，Gao Dashui2，Wu Hongjun3

2002, 21 (05): 693-697

[PDF] 1714 KB (0)

+

Show Abstract

On the bottom of a limestone slope，rocks were excavated，and three interlayers appear in the face of slope. The rock mass above interlayer is most likely sliding. The limit equilibrium method and elasto-plastic finite element method were applied in the analysis on slope stability after and before comprehensive treatment. Anti-slide mass and pre-stress anchor cable technique were applied in the project to keep the slope stable.

Select

STABILITY ANALYSIS ON STEP-SHAPED SLOPE

Shi Weimin1，Ye Xiaoming2，Zheng Yingren1

2002, 21 (05): 698-701 doi:

[PDF] 611 KB (741)

[HTML]

+

Show Abstract

Based on the assumption of straight slip surface，a general expression of safety factor for step-shaped slope is deduced by using the traditional concept of safety factor. Since the deduced expression is analytical equation that is simple and easy to use，the effect of analysis and design of slope stability is improved .

Select

STUDY ON THE CUT SLOPE REINFORCED BY COMPOSITE ANCHORED SYSTEM IN EXPRESSWAY

Tang Shuming1，Lu Changxin2，Deng Anfu3

2002, 21 (05): 702-704

[PDF] 581 KB (0)

+

Show Abstract

The composite anchored system is widely used to reinforce the cut slope of expressway. Some problems in design of this technique are analyzed through a deep cut slope lying in Yuqian expressway in Chongqing. The design methods on determining the distance of ground anchor and selecting the active and passive anchor are proposed.

Select

COMPARISON STUDY ON SOIL NAILING TECHNIQUES IN SLOPE ENGINEERING BETWEEN HONG KONG AND CHONGQING

Yin Ke，Zhang Yongxing

2002, 21 (05): 705-711

[PDF] 399 KB (0)

+

Show Abstract

After twenty years’ research and practice，a series of perfect methods and specifications of design and construction of soil nailing in slope engineering have been developed in Hong Kong. In Chongqing there are many experiences and methods to support weathered mudstone or sandstone slope using soil nails. The technical specification for retaining structure in slope construction，including soil nail technique has been published by Chongqing municipality. These two cities are both mountainous ones. Comparisons study is made on the resemblances and differences of soil nailing in slope support between the two cities and some suggestions are presented.

Select

MULTI-FUNCTIONAL ANCHOR METHOD—— #br# SELF DRILLING-GROUTING ANCHOR #br#

Lin Chenggong 1，2，Wu Delun1

2002, 21 (05): 712-716 doi:

[PDF] 2427 KB (694)

[HTML]

+

Show Abstract

a multi-functional anchor method，that is called self drilling-grouting anchor，is presented. The action mechanism of this method is analysed to grouting results for soil-reinforcement and preloading of anchor. With unique features of the presented method，it can be used to improve the soil strength，and increase the stability of slope during excavation.

Select

STUDY ON DEFORMATION AND STRENGTH CHARACTERISTIC OF EXPANSIVE SOIL WITH TRIAXIAL TESTS

Lu Zaihua，Chen Zhenghan，Sun Shuguo

2002, 21 (05): 717-723 doi:

[PDF] 2071 KB (800)

[HTML]

+

Show Abstract

The triaxial tests of Nanyang unsaturated expansive soil are carried out under four kinds of stress paths，that is isotropic loading tests at various controlled suction，shrinkage tests at various controlled net mean stress，swelling tests at various controlled net mean stress and drained shear tests under controlled cell pressure and suction. Many meaningfull results are obtained. The yield behaviour under isotropic loading of expansive soil can be described by the LC curve，The yield suction of shrinkage test decreases as the net mean stress increasing. The friction angle under unsaturated state is close to that under saturated condition. The total cohesion increases with suction. The water content changes linearly with the net mean stress at isotropic loading test and triaxial shear test. The relationship between water content and suction is also linear under shrinkage test and swelling test.

Select

STUDY ON THE PROPERTY OF ACOUSTIC EMISSION STRAIGHT SHEARING TEST OF ROCK JOINT IN DACHANG TONGKENG MINE

Zhou Xiaoping，Zhang Yongxing

2002, 21 (05): 724-727

[PDF] 650 KB (0)

+

Show Abstract

During the straight shear test of rock joint，the relationship between power-rate and number of acoustic emission events in case of joint failure is studied. It is found that the different stages of deformation and failure of the rock are easily determined by the power-rate.

Select

YIELD ACCELERATION OF REINFORCED EARTH RETAINING WALLS IN EARTHQUAKE ANALYSIS

Yang Ming，Wu Delun，Yan Zhixin

2002, 21 (05): 728-731

[PDF] 1304 KB (0)

+

Show Abstract

Based on the experimental data of reinforced earth retaining walls，the Newmark sliding-block model is used to account for the dynamic behaviour of the reinforced earth retaining walls. The formulation of yield acceleration of the reinforced earth retaining walls is given by the upper bound method of limit analysis. Sensitive analysis shows that the yield acceleration of the reinforced earth retaining walls is affected by wall geometry as well as strength of soil and reinforcements significantly. The obtained conclusions are of good reqularity and can be the foundation of the displacement-controlled design method of the reinforced earth retaining walls.

Select

FINITE ELEMENT METHOD OF UPPER BOUND THEOREM BASED ON THE GENERALIZED PLASTIC THEORY AND ITS APPLICATION

Wang Jinglin1，Deng Chujian1，Zheng Yingren1，Chen Yuyao2

2002, 21 (05): 732-735

[PDF] 593 KB (0)

+

Show Abstract

The associated flow rule for trandional plastic theory is not in accordance with the geotechnical experiment and the non-associated flow rule should be adopted. The finite element method of upper bound theorem based on the generalized plastic theory and its application are presented. The linear programming method is applied to search the minimum upper bound solution. It is proved that the presented method is reasonable and practicable by comparison with classical solution.

Select

NEW ALGORITHM FOR CALCULATION OF RELIABILITY #br# INDEXES OF STRUCTURES #br#

Lei Yong，Wang Ping，Liu Dongsheng

2002, 21 (05): 736-739 doi:

[PDF] 906 KB (850)

[HTML]

+

Show Abstract

Based on the computer seeking，a new algorithm is proposed to calculate the reliability indexes of structures. This method avoids the disadvantages of traditional JC method and has no need to search for the derivatives of limit state functions. So it can be used widely in the reliability indexes of nonlinear limit state functions of structures.

Select

NEW APPROACH OF LANDSLIDE ACTIVITY MONITORING—— PROBING INTO TDR TECHNOLOGY

Wu Xiaolan，Tu Yaqing

2002, 21 (05): 740-744

[PDF] 809 KB (0)

+

Show Abstract

The development of TDR technology is briefly introduced at first. Then the principle of landslide activity monitoring using TDR system is elaborated，and TDR system is analysed in detail. Finally，the advantages and disadvantages of TDR system is discussed compared with traditional monitoring instruments.

Select

FORMATION CONDITION OF HORIZONTAL UNLOADING ARCH IN SOIL LAYER

Ye Xiaoming，Meng Fantao，Xu Nianchun

2002, 21 (05): 745-748

[PDF] 580 KB (0)

+

Show Abstract

The formation condition of horizontal unloading arch in the column-slab structure system is analyzed for slope support. The relation among the horizontal unloading arch，soil parameters c，，coefficient of friction，plane thrust，intercolumnar distance and the width of the column are derived. The quantitative computation method is supplied，and the result is satisfying.

Select

INTERACTION OF PILE，BASE-BEAM AND FRAME UNDER VERTICAL LOAD

Zhu Aijun1，Deng Anfu1，Wang Xiaomin2，Yang Shizhong2

2002, 21 (05): 749-754

[PDF] 1321 KB (0)

+

Show Abstract

Aiming at the circumstances where the face of rock base of southwestern mountain area in China rises and falls seriously，the internal forces of frame structures with the various rock foundations are computed with interaction method and traditional method，and the comparison is made on the two groups of data. The calculation indicates that the pile-top stiffness coefficients differ greatly from each other for the given case，and the inferior stress in the upper structure becomes quite large because of the uneven pile-top settlements.

Select

PREDICTION OF LIMIT BEARING CAPACITY OF BOLT USING ARTIFICAL NEURAL NETWORKS

Xu Ming，Zhang Yongxing，Yin Ke

2002, 21 (05): 755-758

[PDF] 574 KB (0)

+

Show Abstract

Sonoprobe method has been applied in non-destructive inspect of bolt-supported engineering. The fundament of sonoprobe method is that dynamic transient excitation causes the elastic vibration of bolt，and the limit bearing capacity can be estimated or deduced by determining the transient response of the bolt. As a non-linear dynamic system，artifical neural networks are applied to predict the limit bearing capacity of bolt and good result is obtained.