bluuebunny/crossref_metadata_2025 huggingface dataset:
Function of Latent Crack in the Fracture Process of Deep Rock
Authors: Wang Hong Fang , Hu Jiang Chun , Cui Jin Jing
Published: June 2011

Latent crack has no obvious effect on fracture process in the shallow rock engineering. As the project entered into deep part, there appeared many phenomenon which is different from that in the shallow rock engineering, and latent crack plays a more and more important role. By analysis of micro defects of rock and numerical method, potential paths of crack propagation are prefabricated, and adjust the quantity and spreading direction of latent cracks, then by using the numerical test result and mathematical statistics, the paper analyzes the function of latent crack of different level in the process of fracture. The results show that fracture strength and latent crack of rock have close relationship with each other, and rock fracture strength is related to the spreading direction of latent crack, and the smaller the angle between latent crack and major fracture crack is, the greater effect it is on rock fracture strength. As the number of latent crack increase, the effect of the spreading direction of latent crack on rock fracture strength decreases, and the influence degree is depends on their connectivity degree among latent cracks.
Study on Earth Pressure of Foundation Pit Excavation by Model Test
Authors: Wang Gui He , Yang Yu You
Published: June 2011

As there are more and more high-rise buildings in the big cities, some new foundation pits are usually near old high-rise construction. In this case, foundation pit excavation is an engineering problem which needs to be solved urgently. This paper aims at the problem where the new foundation pit is closing to a high-rise building with a cement fly-ash grave (CFG) composite foundation, though cantilever retaining pile model test, simulate the excavate process, and make a testing system to measure datum in order to research on the characteristics of the earth pressure.
An Innovation Simulation Method for Flow State Evolution Laws of Water Inflow and Inrush in Course of Tunnel Excavation (Part II: Applications)
Authors: Xu Zhen Hao , Li Shu Cai , Li Li Ping , Shi Shao Shuai
Published: June 2011

In order to avoid heavy casualties and economic losses, and to get an insight into flow state evolution laws of water inflow and inrush in course of tunnel excavation, simulations were done with COMSOL Multiphysics. By coupling and linking different kinds of sub domain governing equations with boundary conditions and possibly initial conditions, three kinds of water flow state, Darcy’s law for water flow in the limestone aquifer, Brinkman equations for fast fluid in the karst conduit; and incompressible Navier-Stokes equations for freely moving of water in the excavated tunnel, are interacted and coupled with each other. Water pressure and velocity were studied and analyzed in course of tunnel excavation. It is proved that there will be no disastrous water inrush when the seepage deformation of the karst conduit is small, and that it is of vital importance to protect and support the clastic medium of karst conduit, and to strictly guard against any change of the permeability of the karst fillings.
Study on Fatigue Life of Lime Fly-Ash Treated Aggregate Based on SHRP Standard
Authors: Yu Si Xin , Wei Jin Cheng , Ma Shi Jie
Published: June 2011

A new method for fatigue test is developed for semi-rigid pavement materials in this paper, which is much more reliable than the current method in domestic. The max deflection and max tensile strain among different specimens are compiled in flexural bending strength test. And the fatigue equation for lime fly-ash treated aggregate (LFTA) is established.
The Mechanics Analysis and Feedback Design for Shallow Multi-arch Tunnel under Unsymmetrical Pressure
Authors: Pan Hong Ke , Zhang Yu Guo , Hu Jiang Chun , Yang Lin De
Published: June 2011

Shallow multi-arch tunnel under unsymmetrical pressure has complex mechanical behavior to which further study is lacking at present. The existing design methods are thoughtless about the features of shallow and partial pressure. The phenomena of cracks, collapse or other diseases in tunnel lining structure are often seen during the construction or after the completion. Combining one tunnel example, this paper presented scientific feedback design method that suited for Shallow multi-arch tunnel under unsymmetrical pressure: made load back analysis with collected information during construction, then averaged the above load and field monitoring load to make forward analysis and internal force calculation, which was used as reference of reinforcement and sectional design for lining structure.
Activity Degree Evaluation of Glacial Debris Flow along International Karakorum Highway (KKH) Based on Fuzzy Theory
Authors: Yang Zhi Quan , Zhu Ying Yan , Zou D.H.Steve , Liao Li Ping
Published: June 2011

The area of international Karakorum Highway(KKH), is an area with dense and frequent glacial debris flow disasters due to unique geology, geomorphology and landform conditions,which connects northern Pakistan with northwestward China. After in situinvestigation and analyze the present data of these glacier debris flow, by using the fuzzy evaluation method, we selected seven factors,such as occurrence frequency,catchment areas,volumes of alluvial fan,estimated outflow of every time,vegetation coverage, slope and altitude, as main factors for evaluating the activity degree of 8 chosen representative glacier debris flows along KKH. According to the evaluation results,which are showed a good correspond with the practical situation, it can conclude that the fuzzy evaluation method based on the fuzzy mathematics theory is an very effective evaluation method in dealing with glacial debris flow with lots of fuzzy factors,i.e. this method is available for evaluating the activity degree of glacier debris flows.
Study on Modification of Rammed Earth Material in Mountain Areas
Authors: Wang Yun
Published: June 2011

In order to explore the proper modified materials of the raw-soil building in mountain area, the raw-soil modified materials now being used commonly are analyzed effectively at first, and the natural reborn starch resource is thought which has a promising application prospect. In the end, experiments on compressive properties and shear properties of raw-soil material modified by quicklime, slaked lime and starch with different incorporation rates are carried out, and the tests show starch is applicable to modify raw-soil in mountain area.
Numerical Analysis on Deformation of Adjacent Structures due to Metro Station Construction by Enlarging Large-Diameter Shield Tunnel
Authors: Ding De Yun , Yang Xiu Ren , Lu Wei Dong , Liu Wei Ning , Yan Mei
Published: June 2011

Constructing a metro station by enlarging an existing large-diameter shield tunnel can be considered as an attempt to build metro engineering efficiently, safely and economically. To Take the Gaojiayuan station of Beijing metro line 14 as an object of study, two-dimensional finite element models are used to simulate metro station construction by enlarging a large-diameter shield tunnel with an outer diameter of 10 m, based on the soil-tunnel-pipeline-building interaction. According to the theory of orthogonal experimental design, four different supplementary construction measures are considered to study the influence of whether or not adopting the measures on deformation of adjacent structures during enlarging construction. The deformation of adjacent structures is predicted on the basis of adopting four supplementary construction measures. The numerical results can be regarded as a reference for the design and construction of metro station by enlarging large-diameter shield tunnel.
Long-Term Safety Analysis of Tunnel Structure Based on the Performing Degree of Support Strength
Authors: Lai Jin Xing , Liu Xiao Wei , Zhou Fei
Published: June 2011

At present, the new Austrian tunneling method is basically used as the theoretical guidance for domestic tunnel design, which shows that the primary support is not progressed by durability design in the light of service life in the practical work generally acting as the temporary support structure during the period of construction. After the long-term tunnel operation, owing to the erosion of groundwater and the changes of internal stress and external load of surrounding rock, the reinforced of primary support system will be rusted; the bolt, grille arch frame and I-beam will be partially invalidated; the stress of tunnel structure system will be readjusted gradually from the original load-bearing state with dominant position of primary support into the load-bearing state by secondary lining. The Long-term safety analysis refers to the analysis of secondary lining internal force and safety coefficient by load structure model, and the long-term safety analysis of Qingshashan tunnel which is in season frozen zone with complex geological conditions is very necessary.
Experimental Bond Behavior of Mortar Grouted GFRP Rock Bolt
Authors: Weng Qi Neng , Yuan Yong , Zhang Qian Guan
Published: June 2011

Bolts are widely used in slope engineering, tunnel and large cave supporting structures, as well as restoration of engineering structures. They can improve the strength and stability of ground, rock mass, and other structures. The traditional steel bolt has some disadvantages, such as easy corrosion, heavy weight, and difficult operation. Glass Fiber Reinforced Polymer (GFRP) is more resistant to chloride, stronger and lighter than steel. Those advantages make it a better alternative in some fields of engineering. To utilize GFRP bars as rock bolt, some aspects of its behavior, such as bond strength in mortar, bearing capacity, and bond stress distributing along its interface, have to be examined. This paper presents a research on bond behavior of GFRP rock bolts. A concrete block is used to represent rock mass in laboratory. Modified pull out tests were conducted on selected GFRP bars and compared with steel ones that were grouted with mortar in concrete blocks. Bond characteristics of mortar grouted GFRP rock bolts with diameter 16mm were mainly evaluated and other specs of bolts were also discussed.
Numerical Simulation Research on the Settlement Regularity in Pile-Net Composite Foundation
Authors: YU Jin Jiang , Cheng Qian Gong , Li Cheng Hui , Wen Hua
Published: June 2011

Based on the foundation treatment for deep soft soil in Chaoshan station district, this paper studied the engineering characteristics of soft soil in Chaoshan and the settlement regularity of pile-net composite foundation, etc. by numerical simulation. The results show: the reduction of pile spacing and the settings of pile cap can decrease the settlement of soil among the piles on foundation plane.
Research on the United Supporting Structure of Piled Anchor and Reinforced Concrete Internal Bracing for City Deep Foundation Pit under Complex Surroundings
Authors: Hu Jing You , Xie Jian Bin , Li Wei , Li Cheng Hui
Published: June 2011

In this paper, according to the hydrogeology and the surrounding of a 20 meters depth city deep foundation pit which has complex surrounding, the united supporting structure of piled anchor and reinforced concrete internal bracing for this foundation pit was proposed based on the reality that some underground space in surrounding of the foundation pit can not be used. Then according to the possible construction process for foundation pit, the stability of the united supporting structure was calculated and analyzed based on the characteristics of piled anchor and internal bracing. And a case project to support a deep foundation pit by using the united supporting structure of piled anchor and reinforced concrete internal bracing was introduced subsequently. The study results show that the 20 meters depth city deep foundation pit stabilizes integrally when the foundation pit is supported by the united supporting structure. The results also show that settlement of the pit’s surrounding shallow ground is very small, and water-stop curtain of this pit has good performance on piping resistance. It is also certified that the united supporting structure of piled anchor and reinforced concrete internal bracing can meet to the operating requirements of underground space in surrounding.
Thermodynamic Dissolution Model of Limestone and Dolomite and Their Geotechnical Engineering Signification
Authors: Xiao Lin Ping , Li Yong Shu
Published: June 2011

The dissolution of limestone and dolomite is simulated by experiments. The thermodynamic equations are established to study quantitatively the dissolution under the kind of three temperature and pressure conditions, namely 348.15K and 20MPa, 373.15K and 25MPa, 403.15K and 30MPa. Dissolution of the dolomite is much easier and formed porosities or holes than the limestone is .The porosities and holes lead to deposition of oil and natural gas. The Geotechnical Engineering signification of the study is that geological conditions should be considered for the location of new city, highway, railway, tunnel, and so on, to avoid the risk of Geotechnical Engineering disasters.
Numerical Simulation Analysis on a Construction Method of Ultra-Closing Over-Cross Transportation Tunnels
Authors: Yu He Ran , Zhou Xiao Jun , Wang Xiao Bo
Published: June 2011

By numerical simulation approach, this paper analyzed a new construction method for over-cross tunnel. In this method one concrete framework and two connecting walls were used in the intersection zone to meet the requirement of ultra-close distance between the two tunnels: the lining of upper tunnel rode through on the lower one’s via two connecting walls. This paper conducted a series of study on the mechanical behavior of rocks and structures during the construction period. The stability of the structure and the feasibility of construction method were evaluated.
Liquefaction-Induced Ground Deformation of Slopes Using Geostudio2007 Software Program
Authors: Hussain Maula Baydaa , Zhang Ling
Published: June 2011

Liquefaction phenomenon which has produced severe damage all over the world was studied under earthquake record of 0.5g; one of the major effects of liquefaction is lateral spreading. Lateral spreading occurs in sloping grounds and can cause serious damage to structures and lifelines. The objective of this paper is to study the effect of earthquake shaking on soils and slope stability using Geo Studio software 2007. The applicability of the analysis is demonstrated by analysis various slope and embankments subjected to earthquake shaking. This study investigated the effect of embankment slope angle and its geometry on liquefaction. Pore water pressure can be increased by 100% to 35% as β ranged from 35ͦ to 45ͦ respectively, it can see that liquefaction zone induced by earthquake can eliminate as flattering slope and mean while reduced lateral speared displacement. Three case studies are providing to evaluation cyclic stress ratio (CSR) due to earthquake and lateral speared for soils.
Study on Engineering Characteristics of Highly Weathered Weak Rock
Authors: Chen Xiang Yang , Yan Heng Zhen , Liu Xin Xi
Published: June 2011

When highly weathered weak rock used to fill embankment, compaction character and wetting deformation character are major evaluation indexes. Based on California Bearing Ratio (CBR) test for highly weathered weak rock under different compaction degree, it was shown that the value of CBR increased as the increase of compaction degree. By means of dry-wet double curve parallel tests and wetting deformation experiments of different compaction degree of highly weathered weak rock under complex stress, the results indicated that when the degree of compaction is 90%, under rather high deviatoric stress, wetting can not only generate high additional axial deformation, but also cause fairly high additional volumetric strain and partial strain. And wetting cause shear intensity of soil reducing. So increasing the compactions of subgrade filling is the important way to reduce wetting deformation and to enhance slope stability of subgrade.
The Study and Applications on Fiber Bragg Grating (FBG) Monitoring System for Deep and Large Deformed Soft Ground
Authors: Zhang Hong , Liu You Ping , Li Jian Hua , Xiong Mao Dong
Published: June 2011

The fiber Bragg grating (FBG) technology is studied based on the current monitoring status of the highway soft ground settlement, for instance, the low degree of automation, the unsatisfied accuracy of the device, the slow data transmission and the greater measurement errors. The limited measuring range and the difficult situations of the soft ground burying and installing of the fiber optic sensor still need to be addressed. This thesis has analyzed the development of the long range optical fiber displacement sensor as well as its burying techniques which are suitable for soft ground settlement monitoring. Both of them have been successfully applied to De Chang Highway D10 subject. The study also shows that the long range optical fiber displacement sensor is able to meet the requirements of the soft ground monitoring. And data can be accurately monitored by means of real-time or on-line continuously. This is of great significance in pushing forward the development of the fiber optical monitoring technology in the field.
Strain Localization of Sand Based on a State-Dependent Critical State Model
Authors: Hu Ping , Huang Mao Song , Ma Shao Kun , Qin Hui Lai
Published: June 2011

A state-dependent critical state model is employed to analyze strain localization of sand in this paper. The sand model is developed based on the concept of the state-dependent critical state for sands, and an analysis of strain localization is performed on the drained plane strain tests of Hostun sand. The results show that the state-dependent critical state model is capable of simulating the effect of initial state on strain localization compatibly.
Simulation on Triaxial Compression Creep Deformation of Reticulate Red Clay
Authors: Li Jian Zhong , Tang Xi Qing , Yan Lu Chao
Published: June 2011

Triaxial compression creep tests were performed on the undisturbed specimens of reticulate red clay from Dongting Lake area (China) under different confined stress. By analyzing the laboratory test results, following conclusions were drawn: (1) creep deformation occurred in all compression tests; (2) creep deformation increases as the increasing of the creep stress (compress stress) slightly; (3) the creep deformation occurred in the triaxial compression creep tests can be well simulated with Singh-Mitchell model.
Research of Instrument Erecting in the Settlement Observation when Slope Changed
Authors: Li Xian Ju , Peng Chong , Chen Gang
Published: June 2011

The settlement observation usually adopts precision geometric leveling method, to improve the accuracy, generally requiring the value of central cross-hair to be in the range of 0.5m to 2.8m. However, it may easily exceed the range in the regions that have big value of slope. After analyzing, the conclusion is as follow: when the value of slope is certain, we can adjust the height of instrument, sighting distance and distance of slope, so as to make the value of central cross-hair in the range of our requirement. Thus make a compromise of the measurement efficiency and accuracy of measurement. When the values of slope are in the range of 10 degree to 20 degree, the critical values of sighting distance and distance of slope vary greatly. In the process of actual field measurement, combining with the slope acquisition method, taking the critical values of sighting distance and distance of slope as experience values, and it achieves a good effect.
Settlement and Consolidation Mechanism of Cohesive Sedimentation in Estuarine Environment
Authors: Guo Shuai Jie , Wang Bao Tian , Zhang Fu Hai , Chen Liang
Published: June 2011

Estuarine area is the intersection zone of river estuary, coastal and land-phase. Cohesive sediment deposition for mutation affects estuary channel transport and brings great challenges to dredging project. Consolidation indicators are closely related to sedimentation and dredging, and there are apparent errors in application of Terzaghi theory in cohesive sediment consolidation evaluation for large stain characteristics. Then it is necessary to modify some consolidation parameters to extend Terzaghi theory in cohesive sediment consolidation. Considering a whole process of sedimentation and consolidation, a unified equation can be established based on sediment deposition and consolidation theory. Equation parameters can be determined by the simulation test (settlement column experiment). According to the settlement curves and volume fraction distribution curves by simulation experiment, modified consolidation coefficient and the trends can be determined, and modified consolidation coefficient can apply in dredging and deposition project.
Based on Three-Dimensional Limit Equilibrium Slope Stability Analysis of Open Pit
Authors: Jia Lan , Cao Lan Zhu , Song Zi Ling
Published: June 2011

As the complexity and the tall of open pit slope, two-dimensional slope stability analysis methods have been unable to meet the needs of the accuracy of stability analysis. Therefore, for the complex situation of Pingzhuang open pit slope, use with three-dimensional rigid body limit equilibrium method to analysisstability of slope.slope3D system, which consists of pre-treatment, limit equilibrium analysis solver and post-processing, the first processing core is to construct three-dimensional geological model of the slope, post-processing mainly results analysis and visualization graphics. The system combined organically the slope engineering geological information three-dimensional visualization and the analysis of stability, which make us to determine the landslide model, reveal the mechanism of landslide more accurately. Make an important contribution for ensuring safety in open pit production, a good foundation for slope stability analysis of other open pit.
Study of Analytical Solution on Starting Shaft Disaster in Shield Launching
Authors: Wei Xin Jiang , Wei Gang , Hong Jie
Published: June 2011

The causes of water inflow and sand bursting on starting shaft disaster in shield tunnel were analyzed. The analytical model that groundwater seepage from substratum of the reinforced soil to gap in shaft wall on starting shaft in shield tunnelling was established. Using the semi-confined aquifer seepage theory, a practical calculation example was given. The result shows: under the assumption that the reinforced soil was complete exclusion of water, the accidents of water inflow and sand bursting in portal part were influenced by many factors including the length of reinforced soil, groundwater level and so on. The cost and safety of starting shaft engineering had positive correlation with the length of reinforced soil. Lowering the groundwater can significantly reduce water inflow disaster. Comprehensively considered factors of safety, economy, construction period and so on, the reasonable construction parameters can be determined.
Prevention Logic of Rock Burst for Brittle Rock under High Geo-Stress
Authors: Chen Guo Qing , Su Guo Shao , Li Tian Bin
Published: June 2011

Rock burst hazard is the main problem of hard rock deep tunnel under high ground stress conditions. The prevention logic of prevention and control of rock burst is proposed by combining local energy release rate index based on the brittle Hoek-Brown model. Stress releasing holes are adopted to lead some energy to release actively and eliminate burst potential of rock burst. Supporting opportunity and parameters were studied by contrasting the magnitude of released energy in FLAC3D numerical software, and then the prevention logic of rock burst is presented. Stress releasing holes relieve stress concentration of the working face, transfer the stress to the deep and reduce the risk of rock burst near the working face. At last, the prevention and control of rock burst for sinping II Hydropower tunnel was analyzed, the results are in good agreement with the actual situations. The proposed method could benefit other deep tunnel projects which have brittle failure.
Strength Design of Reinforced Soil in the Front of Shield Departure Shaft
Authors: Yang Xian , Zhang Ke Neng
Published: June 2011

In the construction of shield tunnel, the strength of reinforced soil in the front of departure shaft concerns directly the security of construction. Based on Mechanics of Elastic Structures theory, a thin plate model about reinforced soil is introduced, the maximum stress on reinforced soil is calculated. The security of strength in reinforced area is discussed. With the derived formulas, the needed bending and shear strength of reinforced soil in the project of Beijing Metro Line No. 4 is calculated beforehand, and appropriate material and construction parameters are selected in reinforcement according to the calculate result.
Mechanism Study on Transformation of Landslide into Debris Flow based on Coulomb Particle Flow Theory
Authors: Ni Zhen Qiang , Kong Ji Ming , Fayou A.
Published: June 2011

The initiation is the core issue in debris flow study, it’s the basis of debris flow disaster prevention, and the research on transformation of landslide into debris flow is fundamental in debris flow study. Transformation of landslide into debris flow was a new topic which proposed in recent years, although it contained the previous areas of landslide-debris flow, something developed, it was more emphasis on the transformation process of landslide to debris flow. This paper proposed an ideal model from practical disaster, based on Coulomb Particle Flow Theory, we used large-scale finite difference software FLAC3D to analyze. From soil mechanics, to study on excess pore water pressure and the instability mechanism of slope, we got several laws. The results showed that, (a) the maximum excess pore water pressure occurred in the lower part of gravel slope body, with the increase of external load increasing, here would be the first liquefaction area; (b) crushed gravel soil had been largely destroyed when the slope in critical state, and at the same time internal energy of particles increased, cement ability decreased. With the rock sheared, gravitation energy of rock was released, high-speed gravel slope spilled into debris.
Effect Factors Analysis for the Lateral Stability of the Slab Track
Authors: Xu Gui Hong , Li Pei Gang , Zhao Ping Rui , Liu Xue Yi
Published: June 2011

In the paper, a mechanical model for the slab track was established. The mechanical characteristics and the deforming rule of slab track were analyzed using some parameters such as temperature load, the length and radius of circular curve, alignment irregularities, defects of fastening, etc. The results indicate that the lateral displacement of rails is periodically changed under the thermal force. The length and radius of circular curve has influence on the lateral displacement of rail. The lateral displacement of rails mainly influenced by resin’s elastic modulus, and has little relation with the length of circular curve. The mainly influence of resin’s elastic modulus is to the whole lateral displacement of track structure. alignment irregularities had a significant effect on the lateral displacement and track.
Determination of Critical Height of Slope Filled by Red-Bed Soft Rock under Seismic Loading
Authors: Wu Guo Xiong , Chen Xiang Shou , Ding Jing Sheng , Ding Wang Fei
Published: June 2011

The combined influence of the earthquakes and the widespread red-bed soft rock as fill material necessitates the increasing attention on the slope stability in the west region of Yunnan province. To determine the critical height of slope filled by such soft rock under seismic loading, this paper establishes a model simulating a fill slope based on the finite element method and the strength reduction theory. The influence of different slope configurations, including different slope ratios, heights, and side forms on the slope stability is analyzed, and with the stability factor equal or greater than 1.1 as designated in the specifications, the slope critical heights are back calculated. The results show: (1)seismic loading has a significant influence on the slope stability, although its decreasing magnitude slows down with the increase of the slope height.; (2)the fill slope 16m in height is most instable under seismic loading, so the slope at or greater than 16m high is not recommended; (3)whatever the loading forms on the slope, either under the gravity loading only or the combined gravity and seismic loadings, the linear slope is most instable, with increasing stability for concave and step slopes.
Determination of Critical Height of Cut Slope of Red-Bed Soft Rock under Seismic Loading
Authors: Wu Guo Xiong , Cheng Gao Yun , Ding Jing Sheng , Luo Jie
Published: June 2011

The widespread red-bed soft rock, characterized by its poor engineering properties as road building materials, plus the frequent large intensity earthquakes necessitates growing attention on the seismic design of cut slope in the west region of Yunnan province, China. To calculate the critical heights of the slope under seismic loading, a slope model is established and its dynamic response under seismic loading is analyzed by using Fast Lagrangian Analysis of Continua (FLAC3D)based on three-dimensional finite difference method .The reliability of the model is verified by comparing the analytical results with other relevant research results. The stability factors at different slope heights and ratios are gained; accordingly, back calculate the critical heights of the slope at different slope ratios under either the gravity loading only or combined with seismic loading, when the stability factor is equal or greater than 1.1. The above analysis helps provide seismic design guidance for the cut slopes of red soft rock in Yunnan province.
Construction Technology of Geogrid with Simplified Wrapped Face to Reinforce Swelling Rock Slope
Authors: Tan Feng Yi , Zou Rong Hua , Hu Han Bing , Lin Zu Kai
Published: June 2011

The swelling rock slope reinforced by geogrid with wrapped face was one of reinforced methods in the swelling rock test region of main canal in South-to-North Water Division Project, the key step was the geogrid with wrapped face in layer by layer, which was not only the core step to make sure the reinforced swelling rock slope with geogrid as a integrality, but also the most complex, time consuming and cost in the whole process. From the in situ test, the construction technology and related construction parameters of geogrid of simplified face to reinforce the swelling rock slope was obtained, in which the construction of geogrid with wrapped face was optimized, the construction progress was improved and its cost was reduced, which contributed to the generalization and application of geogrid with simplified wrapped face to reinforce swelling rock slope in the middle-route of South-to-North Water Division Project, meanwhile, it was provided as a references for similar engineering.
Study on Section Shape and Support Parameters of Guanjiao Tunnel under Carbonaceous Slate Stratum of the 2nd Line between Xining and Golmud
Authors: Han Xian Min , Sun Ming Lei , Zhu Yong Quan
Published: June 2011

Guanjiao tunnel being reconstructed is the key engineering in the 2nd line between Xingning and Golmud. It is 32.645km long. Carbonaceous slate stratum thereinto is nearly 300m long. The rock mass was suffered tectonic movement and crushed, and its physical and mechanical properties are poor. So large deformation will occur while tunnelling under high horizontal tectonic stress. Numerical simulation along with field experiments were utilized to study the mechnical effect of tunnel section shape. Two kinds of section shapes were considered, that are horseshoe-shaped section and large curvature wall, quasi-circle-shape section. Results show that quasi-circle-shape section could effectively lessen the deformation of tunnel and minish stress concentration of support. Field experiments of different support forms were also conducted. Support forms include Grid steel frame (4×ф22mm)with 0.5m span, I 20a steel frame with 0.67m span and I 20a steel frame with 0.5m span. Pressure of surrounding rock, axial force of anchor, stress of steel frame and shotcrete under different support form were measured and analysed. Because composite lining was adopted in the tunnel, the contact pressure shared by secondary lining and stress of molded concrete under different primary support stiffness were also analysed. Results showed stress of support are rational under support form of I20a. Deformation of tunnel measured in situ under different support forms showed that support form of I20a could control deformation of surrounding rock. Synthetically considering the above and economic benefit, support form of I 20a steel frame with 0.67m span was deemed to be optimal in carbonaceous slate stratum. That could offer engineering experience to tunneling in soft rock under high tectonic stress.
Influences of Loading Mode and Construction Speed on Position of Phreatic Line of a Tailings Dam
Authors: Lei Wei Dong , Fu Tie Lin , Chen Rui , Luo Wen Bin
Published: June 2011

The location of phreatic line of a tailings dam is of significant importance on the stability of the tailings dam. In this study, extensive numerical analysis in ABAQUS have been performed to study the influences of loading mode and construction speed on position of the phreatic line of tailings dam in the process of construction from the existing elevation of 59 m to the final elevation of 100 m. The results show that the location of the phreatic line changes very little at the lower part of the dam; by contrast, the location of phreatic line dramatically changes at the upper part of the dam. At a certain construction speed, loading mode has negligible influence on the position of the phreatic line during the duration of one rising round for the tailings dam. The construction speed has more significant influences on the position of phreatic line in the middle term in the service duration of the tailings dam than in the later period.
Improved Watershed Segmentation Method in Rock Fragmentation Analysis on Digital Photos
Authors: Lei Wei Dong , Li Kai , Wang Xue Ping
Published: June 2011

Reasonable distribution of the rock fragmentation can reduce the overall cost in a mining industry. Digital image processing technique can be used to determine the rock fragmentation distribution function. This paper proposes an improved watershed segmentation method in digital image processing technique. The seven key steps in the new method are presented. Meanwhile, the detailed rock fragmentation analysis is performed on an example digital photo of fragmented rock pile taken from a practical underground mine, to further explain the mechanism of the new method. It is found that the new method can overcome the phenomenon of over-segmentation and over-lapping in digital photos, and exactly detect boundaries for every individual target in the photo.
Mechanism and Prevention of Urban Land Subsidence
Authors: Li Yu Qi , Weng Tian Quan , Liu Yi Ran
Published: June 2011

This paper introduces the hazards of urban land subsidence which caused by excessive extraction of groundwater, the construction of high-rise buildings and excavation, then analyses their mechanisms. It is considered that the essence of land subsidence is due to the soil compaction caused by effective stress augment and the soil loss caused by excavation. Through further analysis of current works, we suggest that regional differences in geological conditions, building loads, repeated action of groundwater withdrawal and recharge, and meso-mechanism of soil particles should be considered when establishing land subsidence model.
Consolidation Process and Triaxial Shear Test of Consolidation Coefficient for Saturated Soft Soil in Marsh
Authors: Liu Hong Jun , Guo Ying , Shan Wei , Tao Xia Xin
Published: June 2011

The consolidation coefficient is the important parameters for soft soil foundation to predict its consolidation settlement. At present, one-way compression test is mainly used to study consolidation process and consolidation coefficient of soft soil. For saturated soft soil in marsh, through triaxial shear test, the dissipation of pore water pressure and consolidation process can be observed during the course of soil sample drainage. This study got test result bellow through above triaxial test. Firstly, pore water pressure has hysteresis effect during the consolidation process, and the reason for this is analyzed. Secondly, consolidation degree in different consolidation time can be got according to the change of discharged water volume. Thirdly, according to Terzaghi consolidation theory, consolidation coefficients can be got under different consolidation pressures. Consolidation coefficient first increases with the increasing of consolidation degree, when consolidation degree is between 40% and 80%, saturated soft soil has larger consolidation coefficient, consolidation coefficient of saturated soft soil in marsh is between 2Ч10-4 cm2 / s and 10Ч10-4cm2 / s.
The Influence of Water Content on the Parameters of Geogrid-Soil Interface
Authors: Liu Hong Jun , Guo Ying , Shan Wei , Wang Pi Xiang
Published: June 2011

The method of evaluating the effect of geogrid reinforcement mainly is the finite element method at present. The interface between geogrid and soil is set to contacting element normally. The tangential stiffness expression has five parameters totally. The interaction characteristics of geosynthetics and filled soil are related to the soil type and water content. We designed the experimental research program, using direct shear friction test, study the five parameters of the interface between geogrid and soil varied with water content and soil type. The experimental results show that: Whether weathered sands or silty clay, the value of the parameters (k1,n,c,φ) increase with the increase of water content, when reaching the peak point, then the value of the parameters (k1,n,c,φ) will decreases with the increase of water content. The water content corresponding to the peak is near the optimum water content. The value of the parameters (Rf) decreases with the increase of water content, when reaching a minimum, the value of the parameters (Rf) will increase with the increase of water content. The water content corresponding to the minimum also is near the optimum water content. The research results can provide reliable basis for the selection of evaluation parameters.
Effect of Crushed Clay Brick as Coarse Aggregate on Creep Behavior of Concrete
Authors: Syed Ishtiaq Ahmad , Sushanta Roy
Published: June 2011

Difference between creep behaviors of concrete made from stone chips and crushed clay bricks, i.e. brick chips as coarse aggregate are examined by means of creep testing on their representative samples. Two different grades of concrete 17.2 and 27.5 N/mm2 are prepared from brick chips and stone chips using appropriate mix design and are tested for creep for up to 50 days. Stone chips and brick chips aggregates used are selected in a way so that their gradation and fineness modulus remains as close as possible. Results from creep testing shows that concrete made from brick chips as coarse aggregate having same strength as that of concrete made from stone chips shows higher creep strain. As concrete strength increases, the difference in creep strain becomes more pronounced. Also, at initial loading condition, concrete made from brick chips shows higher rate of creep strain than that of concrete made from stone chips.
Time Series Forecasting of Tunnel Surrounding Rock Displacement
Authors: Mao Guang Xiang , Xia Yuan You , Liu Ling Wei
Published: June 2011

In the process of tunnel construction, because the rock stress redistribute, the vault and the two groups will generate displacement constantly. This paper adopts the genetic algorithm to optimize the weight and threshold of BP neural network, taking the tunnel depth, rock types and part measured values of displacement as input parameters to construct a neural network time series prediction model of tunnel surrounding rock displacement. The method proposed in the paper has been applied in the Ma Tou Tang tunnel construction successfully, and the results show that the model can predict the displacement of the surrounding rock quickly and accurately.
Study on Stress Difference-Strength Ratio Rockburst Classification by Rock Unloading Test
Authors: Zhang Li Ming , Wang Zai Quan
Published: June 2011

Rockburst happened during underground excavation caused by stress re-distribution of surrounding rocks. Stress difference was critical factor to determine whether rockburst happened or not. The stress difference-strength ratio method of rockburst classification was put forward. Rockburst intensities of the same size and different cave shapes were calculated without considering the influence of excavation unloading and considering the influence of excavation unloading by finite element method. Results showed that the grade of rockburst predicted by the stress difference-strength ratio method was lower than by stress-strength ratio method. Rockburst grade was lower one grade for not considering the excavation unloading.
A Modified Shear Displacement Method for Calculating Settlement of Single Pile
Authors: Zhang Qian Qing , Zhang Zhong Miao
Published: June 2011

A modified shear displacement method is presented to analyze the load-settlement response of a single pile in homogenous soil using two models. One model adopts a hyperbolic model to simulate the stress-strain relationship of soil under shear stress before failure occurs, and the other model uses a non-linear stress-strain relationship to evaluate the load-displacement behavior of the soil beneath the pile base. Comparisons of the load-settlement responses between the present modified model and the model suggested by Randolph and Wroth are given to demonstrate the effectiveness and accuracy of the proposed modified method.
Damage Model of Concrete Durability under Coupled Action of Stress and Freeze-Thaw Cycles
Authors: Zheng Dan , Zhou Jian Ting
Published: June 2011

Based on damage mechanics and thermo, the mechanical degradation of concrete material under the coupled action of stress and freeze-thaw cycles was analyzed in this paper. The tensile stress in concrete during freeze-thaw cycles was obtained considering freezing-induced pore pressure variation with the change of temperature. A revised fatigue fracture model is proposed for the reliability analysis of concrete durability, which can evaluate damage status and the remaining service life of concrete structure after freeze-thaw cycles with different loading levels. The present model can serve as references for design and safety assessment for concrete structures in cold regions.
Experimental Study of Compressive Bearing Capacity of Pile-Bucket Foundation
Authors: Liu Wen Bai , Li Ye , Wang Da Shan
Published: June 2011

By combining indoor model experiment and numerical simulation, the analysis of pile-bucket foundation bearing capacity under pressure load was conducted, and the bearing capacity can be enhanced by enlarging the three main dimensions of pile-bucket foundation: diameter of bucket, height of bucket and length of pile. By enlarging the diameter of bucket by 1.5 times while maintaining the two other dimensions, the bearing capacity can be enhanced by 140%;the bearing capacity can be enhanced by 15% when the height of bucket is enlarged by 2 times; the bearing capacity can be enhanced by 14% when the pile length is enlarged by 30% ,that means the variation of bucket diameter affects the pile-bucket foundation bearing capacity most, apart from that the variation of bucket diameter also holds the most obvious effect on the ground foundation soil body in crosswise scope, the bucket diameter of 3# pile-bucket was 1.5 times that of 1# pile-bucket, after the surrounding soil broke, the influence scope on crosswise soil surface was enhanced by the size 3.8 times breadth of bucket diameter; and the pile-length variation keeps the largest effect on surrounding soil body in-depth, the depth of effect on grounding soil of 1#pile-bucket is enlarged by 925mm comparing by 2#pile-bucket (approximately 9 times of bucket diameter) ; By conducting indoor-model pressure bearing capacity experiment on pile –bucket foundation,bucket foundation and circular-shape shallow foundation with same diameter, the limiting bearing capacity of pile-bucket foundation is 3.2 times that of circular-shape shallow foundation and 1.26 times that of bucket foundation, a manifestation of the bearing capacity advantage of pile-bucket foundation.
Experimental Research on Main Properties of New Recycled Coarse Aggregate Concrete
Authors: Qian Da Xing , Yun Ying Wei , Jang Ii Young , Kim Jong Hoe
Published: June 2011

Recently reutilization of waste concrete becomes one of the hottest issues in civil engineering field throughout the world. However, most of the concerned research focuses on the RCA (recycled coarse aggregate) by simply crushing waste concrete. In this paper shucking technique is developed to secondary process the simply crushing waste concrete for improving the performance of RCA concrete. Test has been done to demonstrate that performances such as strength, elastic modulus et al. of shucking RCA concrete is better than those of common recycled concrete. Simultaneously, beam specimens are made to test the flexural behavior of shucking RCA concrete. Results showed that the deflection of shucking RCA concrete beam is approximately same with that of natural coarse aggregate concrete beam, which solves current problem that recycled aggregate concrete beam has bigger deflection than common concrete beam. The new shucking technique developed in this paper has many advantages to be applied in practical engineering and it has obvious economic benefits and social effect.
Experimental Investigation on Stress-Strain Curves of Reactive Powder Concrete under Uniaxial Compression
Authors: Ju Yan Zhong , Wang De Hong , Jiang Fei
Published: June 2011

Based on experiments of uniaxial compression and flexural experiments, the basic mechanical properties (compressive strength and flexural strength) of reactive powder concrete (RPC) were investigated, the effect of the steel fiber content on mechanical properties of RPC was studied in this work. The resu1ts indicate that the axial compressive strength of RPC had no obvious change with the change of steel fiber content. When the steel fiber content varied from 1.0% to 2.0%, the flexural strength of RPC had no obvious change.When the steel fiber content varied from 2.0% to 5.0%, the flexural strength of RPC increased dramaticlly with the increase of steel fibers content. According to experiment curves, an equation for the compressive stress-strain curve of RPC was deduced with different stee1 fiber content.
Multi-Objective Optimized Design of High-Performance Concrete Based on Matlab
Authors: Xie Xian Song , Zheng Yue Zhai , Tian Fang
Published: June 2011

Based on the Compressive strength, workability and raw material consumption of concrete, a mathematical model is established for mix proportion design of high performance concrete (hereinafter referred to as HPC) with chlorine ion’s diffusion coefficient and per cubic meter cost as its optimized objectives. Matlab’s Sequential Quadratic Programming method is used for the solution of constrained nonlinear problems, with which the calculation and optimization of mix proportion of concrete are solved satisfactorily. HPC with optimized design can meet all requirements for its type and has obvious economic benefit.