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1The Hoeke-Brown failure criterion and GSI-2018 edition显示文摘The HoekeBrown criterion was introduced in 1980 to provide input for the design of underground excavations in rock.The criterion now incorporates both intact rock and discontinuities,such as joints,characterized by the geological strength index(GSI),into a system designed to estimate the mechanical behaviour of typical rock masses encountered in tunnels,slopes and foundations.The strength and deformation properties of intact rock,derived from laboratory tests,are reduced based on the properties of discontinuities in the rock mass.The nonlinear HoekeBrown criterion for rock masses is widely accepted and has been applied in many projects around the world.While,in general,it has been found to provide satisfactory estimates,there are several questions on the limits of its applicability and on the inaccuracies related to the quality of the input data.This paper introduces relatively few fundamental changes,but it does discuss many of the issues of utilization and presents case histories to demonstrate practical applications of the criterion and the GSI system.E.Hoek E.T.Brown 2019Journal of Rock Mechanics and Geotechnical Engineering2019,11,3:85
2Dynamic rock tests using split Hopkinson (Kolsky) bar system - A review显示文摘Dynamic properties of rocks are important in a variety of rock mechanics and rock engineering problems.Due to the transient nature of the loading, dynamic tests of rock materials are very different from and much more challenging than their static counterparts. Dynamic tests are usually conducted using the split Hopkinson bar or Kolsky bar systems, which include both split Hopkinson pressure bar(SHPB) and split Hopkinson tension bar(SHTB) systems. Signi fi cant progress has been made on the quanti fi cation of various rock dynamic properties, owing to the advances in the experimental techniques of SHPB system.This review aims to fully describe and critically assess the detailed procedures and principles of techniques for dynamic rock tests using split Hopkinson bars. The history and principles of SHPB are outlined,followed by the key loading techniques that are useful for dynamic rock tests with SHPB(i.e. pulse shaping, momentum-trap and multi-axial loading techniques). Various measurement techniques for rock tests in SHPB(i.e. X-ray micro computed tomography(CT), laser gap gauge(LGG), digital image correlation(DIC), Moiré method, caustics method, photoelastic coating method, dynamic infrared thermography) are then discussed. As the main objective of the review, various dynamic measurement techniques for rocks using SHPB are described, including dynamic rock strength measurements(i.e.dynamic compression, tension, bending and shear tests), dynamic fracture measurements(i.e. dynamic imitation and propagation fracture toughness, dynamic fracture energy and fracture velocity), and dynamic techniques for studying the in fl uences of temperature and pore water.Kaiwen Xia Wei Yao 2015Journal of Rock Mechanics and Geotechnical Engineering2015,7,1:72
3The influence of microwave irradiation on rocks for microwaveassisted underground excavation显示文摘Demand is growing for explosive-free rock breakage systems for civil and mining engineering, and spaceindustry applications. This paper highlights the work being undertaken in the Geomechanics Laboratoryof McGill University to make a real application of microwave-assisted mechanical rock breakage to fullfacetunneling machines and drilling. Comprehensive laboratory tests investigated the effect of microwaveradiation on temperature profiles and strength reduction in hard rocks (norite, granite, and basalt)for a range of exposure times and microwave power levels. The heating rate on the surface of the rockspecimens linearly decreased with distance between the sample and the microwave antenna, regardlessof microwave power level and exposure time. Tensile and uniaxial compressive strengths were reducedwith increasing exposure time and power level. Scanning electron micrographs (SEMs) highlightedfracture development in treated basalt. It was concluded that the microwave power level has a strongpositive influence on the amount of heat damage induced to the rock surface. Numerical simulations ofelectric field intensity and wave propagation conducted with COMSOL Multiphysics software generatedtemperature profiles that were in close agreement with experimental results.Ferri Hassani Pejman M.Nekoovaght Nima Gharib 2016Journal of Rock Mechanics and Geotechnical Engineering2016,8,1:69
4The Beishan underground research laboratory for geological disposal of high-level radioactive waste in China:Planning, site selection,site characterization and in situ tests显示文摘With the rapid development of nuclear power in China, the disposal of high-level radioactive waste(HLW) has become an important issue for nuclear safety and environmental protection. Deep geological disposal is internationally accepted as a feasible and safe way to dispose of HLW, and underground research laboratories(URLs) play an important and multi-faceted role in the development of HLW repositories. This paper introduces the overall planning and the latest progress for China's URL. On the basis of the proposed strategy to build an area-specific URL in combination with a comprehensive evaluation of the site selection results obtained during the last 33 years, the Xinchang site in the Beishan area,located in Gansu Province of northwestern China, has been selected as the final site for China's first URL built in granite. In the process of characterizing the Xinchang URL site, a series of investigations,including borehole drilling,geological mapping, geophysical surveying,hydraulic testing and in situ stress measurements, has been conducted. The investigation results indicate that the geological,hydrogeological, engineering geological and geochemical conditions of the Xinchang site are very suitable for URL construction. Meanwhile, to validate and develop construction technologies for the Beishan URL, the Beishan exploration tunnel(BET), which is a 50-m-deep facility in the Jiujing sub-area, has been constructed and several in situ tests, such as drill-and-blast tests, characterization of the excavation damaged zone(EDZ), and long-term deformation monitoring of surrounding rocks, have been performed in the BET. The methodologies and technologies established in the BET will serve for URL construction.According to the achievements of the characterization of the URL site, a preliminary design of the URL with a maximum depth of 560 m is proposed and necessary in situ tests in the URL are planned.Ju Wang Liang Chen Rui Su Xingguang Zhao 2018Journal of Rock Mechanics and Geotechnical Engineering2018,10,3:62
5Failure mechanism and coupled static-dynamic loading theory in deep hard rock mining: A review显示文摘Rock failure phenomena,such as rockburst,slabbing(or spalling) and zonal disintegration,related to deep underground excavation of hard rocks are frequently reported and pose a great threat to deep mining.Currently,the explanation for these failure phenomena using existing dynamic or static rock mechanics theory is not straightforward.In this study,new theory and testing method for deep underground rock mass under coupled static-dynamic loading are introduced.Two types of coupled loading modes,i.e.'critical static stress + slight disturbance' and 'elastic static stress + impact disturbance',are proposed,and associated test devices are developed.Rockburst phenomena of hard rocks under coupled static-dynamic loading are successfully reproduced in the laboratory,and the rockburst mechanism and related criteria are demonstrated.The results of true triaxial unloading compression tests on granite and red sandstone indicate that the unloading can induce slabbing when the confining pressure exceeds a certain threshold,and the slabbing failure strength is lower than the shear failure strength according to the conventional Mohr-Column criterion.Numerical results indicate that the rock unloading failure response under different in situ stresses and unloading rates can be characterized by an equivalent strain energy density.In addition,we present a new microseismic source location method without premeasuring the sound wave velocity in rock mass,which can efficiently and accurately locate the rock failure in hard rock mines.Also,a new idea for deep hard rock mining using a non-explosive continuous mining method is briefly introduced.Xibing Li Fengqiang Gong Ming Tao Longjun Dong Kun Du Chunde Ma Zilong Zhou Tubing Yin 2017Journal of Rock Mechanics and Geotechnical Engineering2017,9,4:68
6A review of discrete modeling techniques for fracturing processes in discontinuous rock masses显示文摘The goal of this review paper is to provide a summary of selected discrete element and hybrid finitee discrete element modeling techniques that have emerged in the field of rock mechanics as simulation tools for fracturing processes in rocks and rock masses. The fundamental principles of each computer code are illustrated with particular emphasis on the approach specifically adopted to simulate fracture nucleation and propagation and to account for the presence of rock mass discontinuities. This description is accompanied by a brief review of application studies focusing on laboratory-scale models of rock failure processes and on the simulation of damage development around underground excavations.A.Lisjak G.Grasselli 2014Journal of Rock Mechanics and Geotechnical Engineering2014,6,4:58
7Longwall mining “cutting cantilever beam theory” and 110 mining method in China——The third mining science innovation显示文摘With the third innovation in science and technology worldwide, China has also experienced this marvelous progress. Concerning the longwall mining in China, the 'masonry beam theory'(MBT) was first proposed in the 1960 s, illustrating that the transmission and equilibrium method of overburden pressure using reserved coal pillar in mined-out areas can be realized. This forms the so-called '121mining method', which lays a solid foundation for development of mining science and technology in China. The 'transfer rock beam theory'(TRBT) proposed in the 1980 s gives a further understanding for the transmission path of stope overburden pressure and pressure distribution in high-stress areas. In this regard, the advanced 121 mining method was proposed with smaller coal pillar for excavation design,making significant contributions to improvement of the coal recovery rate in that era. In the 21 st century,the traditional mining technologies faced great challenges and, under the theoretical developments pioneered by Profs. Minggao Qian and Zhenqi Song, the 'cutting cantilever beam theory'(CCBT) was proposed in 2008. After that the 110 mining method is formulated subsequently, namely one stope face,after the first mining cycle, needs one advanced gateway excavation, while the other one is automatically formed during the last mining cycle without coal pillars left in the mining area. This method can be implemented using the CCBT by incorporating the key technologies, including the directional presplitting roof cutting, constant resistance and large deformation(CRLD) bolt/anchor supporting system with negative Poisson's ratio(NPR) effect material, and remote real-time monitoring technology. The CCBT and 110 mining method will provide the theoretical and technical basis for the development of mining industry in China.Manchao He Guolong Zhu Zhibiao Guo 2015Journal of Rock Mechanics and Geotechnical Engineering2015,7,5:57
8Shear strength criteria for rock,rock joints,rockfill and rock masses:Problems and some solutions显示文摘Although many intact rock types can be very strong,a critical confining pressure can eventually be reached in triaxial testing,such that the Mohr shear strength envelope becomes horizontal.This critical state has recently been better defined,and correct curvature or correct deviation from linear Mohr-Coulomb(MC) has finally been found.Standard shear testing procedures for rock joints,using multiple testing of the same sample,in case of insufficient samples,can be shown to exaggerate apparent cohesion.Even rough joints do not have any cohesion,but instead have very high friction angles at low stress,due to strong dilation.Rock masses,implying problems of large-scale interaction with engineering structures,may have both cohesive and frictional strength components.However,it is not correct to add these,following linear M-C or nonlinear Hoek-Brown(H-B) standard routines.Cohesion is broken at small strain,while friction is mobilized at larger strain and remains to the end of the shear deformation.The criterion 'c then σn tan φ' should replace 'c plus σn tan φ' for improved fit to reality.Transformation of principal stresses to a shear plane seems to ignore mobilized dilation,and caused great experimental difficulties until understood.There seems to be plenty of room for continued research,so that errors of judgement of the last 50 years can be corrected.Nick Barton 2013Journal of Rock Mechanics and Geotechnical Engineering2013,5,4:41
9Fracture initiation and propagation in intact rock—A review显示文摘The initiation and propagation of failure in intact rock are a matter of fundamental importance in rock engineering. At low confining pressures, tensile fracturing initiates in samples at 40%e60% of the uniaxial compressive strength and as loading continues, and these tensile fractures increase in density, ultimately coalescing and leading to strain localization and macro-scale shear failure of the samples. The Griffith theory of brittle failure provides a simplified model and a useful basis for discussion of this process. The HoekeBrown failure criterion provides an acceptable estimate of the peak strength for shear failure but a cutoff has been added for tensile conditions. However, neither of these criteria adequately explains the progressive coalition of tensile cracks and the final shearing of the specimens at higher confining stresses. Grain-based numerical models, in which the grain size distributions as well as the physical properties of the component grains of the rock are incorporated, have proved to be very useful in studying these more complex fracture processes.E.Hoek C.D.Martin 2014Journal of Rock Mechanics and Geotechnical Engineering2014,6,4:43
10Reservoir-induced landslides and risk control in Three Gorges Project on Yangtze River,China显示文摘The Three Gorges region in China was basically a geohazard-prone area prior to construction of the Three Gorges Reservoir(TGR).After construction of the TGR,the water level was raised from 70 m to 175 m above sea level(ASL).and annual reservoir regulation has caused a 30-m water level difference after impoundment of the TGR since September 2008.This paper first presents the spatiotemporal distribution of landslides in six periods of 175 m ASL trial impoundments from 2008 to 2014.The results show that the number of landslides sharply decreased from 273 at the initial stage to less than ten at the second stage of impoundment.Based on this,the reservoir-induced landslides in the TGR region can be roughly classified into five failure patterns,i.e.accumulation landslide,dip-slope landslide,reversed bedding landslide,rockfall,and karst breccia landslide.The accumulation landslides and dip-slope landslides account for more than 90%.Taking the Shuping accumulation landslide(a sliding mass volume of 20.7 × 10~6 m^3) in Zigui County and the Outang dip-slope landslide(a sliding mass volume of about 90 × 10~6 m^3) in Fengjie County as two typical cases,the mechanisms of reactivation of the two landslides are analyzed.The monitoring data and factor of safety(FOS) calculation show that the accumulation landslide is dominated by water level variation in the reservoir as most part of the mass body is under 175 m ASL,and the dip-slope landslide is controlled by the coupling effect of reservoir water level variation and precipitation as an extensive recharge area of rainfall from the rear and the front mass is below 175 m ASL.The characteristics of landslide-induced impulsive wave hazards after and before reservoir impoundment are studied,and the probability of occurrence of a landslide-induced impulsive wave hazard has increased in the reservoir region.Simulation results of the Ganjingzi landslide in Wushan County indicate the strong relationship between landslide-induced surge and water variation with high potential risk to shipping and residential areas.Regarding reservoir regulation in TGR when using a single index,i.e.1-d water level variation,water resources are not well utilized,and there is also potential risk of disasters since 2008.In addition,various indices such as 1-d.5-d,and 10-d water level variations are proposed for reservoir regulation.Finally,taking reservoir-induced landslides in June2015 for example,the feasibility of the optimizing indices of water level variations is verified.Yueping Yin Bolin Huang Wenpei Wang Yunjie Wei Xiaohan Ma Fei Ma Changjun Zhao 2016Journal of Rock Mechanics and Geotechnical Engineering2016,8,5:45
11Energy analysis and criteria for structural failure of rocks显示文摘The intrinsic relationships between energy dissipation,energy release,strength and abrupt structural failure are key to understanding the evolution of deformational processes in rocks.Theoretical and experimental studies confirm that energy plays an important role in rock deformation and failure.Dissipated energy from external forces produces damage and irreversible deformation within rock and decreases rock strength over time.Structural failure of rocks is caused by an abrupt release of strain energy that manifests as a catastrophic breakdown of the rock under certain conditions.The strain energy released in the rock volume plays a pivotal role in generating this abrupt structural failure in the rocks.In this paper,we propose criteria governing(1) the deterioration of rock strength based on energy dissipation and(2) the abrupt structural failure of rocks based on energy release.The critical stresses at the time of abrupt structural failure under various stress states can be determined by these criteria.As an example,the criteria have been used to analyze the failure conditions of surrounding rock of a circular tunnel.Heping Xie Liyun Li Ruidong Peng Yang Ju 2009Journal of Rock Mechanics and Geotechnical Engineering2009,1,1:39
12High-level radioactive waste disposal in China: update 2010显示文摘For geological disposal of high-level radioactive waste (HLW), the Chinese policy is that the spent nuclear fuel (SNF) should be reprocessed first, followed by vitrification and final disposal. The preliminary repository concept is a shaft-tunnel model, located in saturated zones in granite, while the final waste form for disposal is vitrified high-level radioactive waste. In 2006, the government published a long-term research and development (R&D) plan for geological disposal of high-level radioactive waste. The program consists of three steps: (1) laboratory studies and site selection for a HLW repository (2006–2020); (2) underground in-situ tests (2021–2040); and (3) repository construction (2041–2050) followed by operation. With the support of China Atomic Energy Authority, comprehensive studies are underway and some progresses are made. The site characterization, including deep borehole drilling, has been performed at the most potential Beishan site in Gansu Province, Northwestern China. The data from geological and hydrogeological investigations, in-situ stress and permeability measurements of rock mass are presented in this paper. Engineered barrier studies are concentrated on the Gaomiaozi bentonite. A mock-up facility, which is used to study the thermo-hydro-mechano-chemical (THMC) properties of the bentonite, is under construction. Several projects on mechanical properties of Beishan granite are also underway. The key scientific challenges faced with HLW disposal are also discussed.Ju Wang 2010Journal of Rock Mechanics and Geotechnical Engineering2010,2,1:35
13Design of rock support system under rockburst condition显示文摘As mining and civil tunneling progresses to depth, excavation-induced seismicity and rockburst problems increase and cannot be prevented. As an important line of defense, ground control measures and burst-resistant rock support are used to prevent or minimize damage to excavations and thus to enhance workplace safety. Rock support in burst-prone ground differs from conventional rock support where controlling gravity-induced rockfalls and managing shallow zones of loose rock are the main target. Rock support in burst-prone ground needs to resist dynamic loads and large rock dilation due to violent rock failure. After reviewing the rockburst phenomenon, types of rockbursts, damage mechanisms, and rockburst support design principles and acceptability criteria, this paper describes that the support selection process in burst-prone ground is iterative, requiring design verification and modification based on field observations. An interactive design tool for conducting rockburst support design in underground tunnels is introduced to facilitate cost-effective design.Peter K. Kaiser 2012Journal of Rock Mechanics and Geotechnical Engineering2012,4,3:32
14Preliminary engineering application of microseismic monitoring technique to rockburst prediction in tunneling of Jinping Ⅱ project显示文摘Monitoring and prediction of rockburst remain to be worldwide challenges in geotechnical engineering.In hydropower,transportation and other engineering fields in China,more deep,long and large tunnels have been under construction in recent years and underground caverns are more evidently featured by 'long,large,deep and in group',which bring in many problems associated with rock mechanics problems at great depth,especially rockburst.Rockbursts lead to damages to not only underground structures and equipments but also personnel safety.It has been a major technical bottleneck in future deep underground engineering in China.In this paper,compared with earthquake prediction,the feasibility in principle of monitoring and prediction of rockbursts is discussed,considering the source zones,development cycle and scale.The authors think the feasibility of rockburst prediction can be understood in three aspects:(1) the heterogeneity of rock is the main reason for the existence of rockburst precursors;(2) deformation localization is the intrinsic cause of rockburst;and(3) the interaction between target rock mass and its surrounding rock mass is the external cause of rockburst.As an engineering practice,the application of microseismic monitoring techniques during tunnel construction of Jinping II Hydropower Station was reported.It is found that precursory microcracking exists prior to most rockbursts,which could be captured by the microseismic monitoring system.The stress concentration is evident near structural discontinuities(such as faults or joints),which shall be the focus of rockburst monitoring.It is concluded that,by integrating the microseismic monitoring and the rock failure process simulation,the feasibility of rockburst prediction is expected to be enhanced.Chun'an Tang Jimin Wang Jingjian Zhang 2010Journal of Rock Mechanics and Geotechnical Engineering2010,2,3:32
15A semi-spring and semi-edge combined contact model in CDEM and its application to analysis of Jiweishan landslide显示文摘Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.Chun Feng Shihai Li Xiaoyu Liu Yanan Zhang 2014Journal of Rock Mechanics and Geotechnical Engineering2014,6,1:34
16Safety risk management of underground engineering in China:Progress, challenges and strategies显示文摘Underground construction in China is featured by large scale, high speed, long construction period,complex operation and frustrating situations regarding project safety. Various accidents have been reported from time to time, resulting in serious social impact and huge economic loss. This paper presents the main progress in the safety risk management of underground engineering in China over the last decade, i.e.(1) establishment of laws and regulations for safety risk management of underground engineering,(2) implementation of the safety risk management plan,(3) establishment of decision support system for risk management and early-warning based on information technology, and(4) strengthening the study on safety risk management, prediction and prevention. Based on the analysis of the typical accidents in China in the last decade, the new challenges in the safety risk management for underground engineering are identified as follows:(1) control of unsafe human behaviors;(2) technological innovation in safety risk management; and(3) design of safety risk management regulations. Finally, the strategies for safety risk management of underground engineering in China are proposed in six aspects, i.e. the safety risk management system and policy, law, administration, economy, education and technology.Qihu Qian Peng Lin 2016Journal of Rock Mechanics and Geotechnical Engineering2016,8,4:28
17Protection against water or mud inrush in tunnels by grouting:A review显示文摘Grouting is a major method used to prevent water and mud inrush in tunnels and underground engineering.In this paper,the current situation of control and prevention of water and mud inrush is summarized and recent advances in relevant theories,grout/equipment,and critical techniques are introduced.The time-variant equations of grout viscosity at different volumetric ratios were obtained based on the constitutive relation of typical fast curing grouts.A large-scale dynamic grouting model testing system(4000 mm × 2000 mm × 5 mm) was developed,and the diffusions of cement and fast curing grouts in dynamic water grouting were investigated.The results reveal that the diffusions of cement grouts and fast curing grouts are U-shaped and asymmetric elliptical,respectively.A multiparameter real-time monitoring system(φ = 1.5 m,h = 1.2 m) was developed for the grouting process to study the diffusion and reinforcement mechanism of grouting in water-rich faulted zone.A high early strength cream-type reinforcing/plugging grout,a high permeability nano-scale silica gel grout,and a high-expansion filling grout were proposed for the control of water hazards in weak water-rich faulted zone rocks,water inrush in karst passages,and micro-crack water inrush,respectively.Complement technologies and equipment for industrial applications were also proposed.Additionally,a novel full-life periodic dynamic water grouting with the critical grouting borehole as the core was proposed.The key techniques for the control of water inrush in water-rich faulted zone,jointed fissures and karst passages,and micro-crack water inrush were developed.Shucai Li Rentai Liu Qingsong Zhang Xiao Zhang 2016Journal of Rock Mechanics and Geotechnical Engineering2016,8,5:27
18Innovation and future of mining rock mechanics显示文摘The 121 mining method of longwall mining first proposed in England has been widely used around the world.This method requires excavation of two mining roadways and reservation of one coal pillar to mine one working face.Due to considerable excavation of roadway,the mining roadway is generally destroyed during coal mining.The stress concentration in the coal pillar can cause large deformation of surrounding rocks,rockbursts and other disasters,and subsequently a large volume of coal pillar resources will be wasted.To improve the coal recovery rate and reduce excavation of the mining roadway,the 111 mining method of longwall mining was proposed in the former Soviet Union based on the 121 mining method.The 111 mining method requires excavation of one mining roadway and setting one filling body to replace the coal pillar while maintaining another mining roadway to mine one working face.However,because the stress transfer structure of roadway and working face roof has not changed,the problem of stress concentration in the surrounding rocks of roadway has not been well solved.To solve the above problems,the conventional concept utilizing high-strength support to resist the mining pressure for the 121 and 111 mining methods should be updated.The idea is to utilize mining pressure and expansion characteristics of the collapsed rock mass in the goaf to automatically form roadways,avoiding roadway excavation and waste of coal pillar.Based on the basic principles of mining rock mechanics,the“equilibrium mining”theory and the“short cantilever beam”mechanical model are proposed.Key technologies,such as roof directional presplitting technology,negative Poisson’s ratio(NPR)high-prestress constant-resistance support technology,and gangue blocking support technology,are developed following the“equilibrium mining”theory.Accordingly,the 110 and N00 mining methods of an automatically formed roadway(AFR)by roof cutting and pressure releasing without pillars are proposed.The mining methods have been applied to a large number of coal mines with different overburdens,coal seam thicknesses,roof types and gases in China,realizing the integrated mode of coal mining and roadway retaining.On this basis,in view of the complex geological conditions and intelligent mining demand of coal mines,an intelligent and unmanned development direction of the“equilibrium mining”method is prospected.Manchao He Qi Wang Qunying Wu 2021Journal of Rock Mechanics and Geotechnical Engineering2021,13,1:28
19Predicting geological hazards during tunnel construction显示文摘The complicated geological conditions and geological hazards are challenging problems during tunnel construction,which will cause great losses of life and property.Therefore,reliable prediction of geological defective features,such as faults,karst caves and groundwater,has important practical significances and theoretical values.In this paper,we presented the criteria for detecting typical geological anomalies using the tunnel seismic prediction(TSP) method.The ground penetrating radar(GPR) signal response to water-bearing structures was used for theoretical derivations.And the 3D tomography of the transient electromagnetic method(TEM) was used to develop an equivalent conductance method.Based on the improvement of a single prediction technique,we developed a technical system for reliable prediction of geological defective features by analyzing the advantages and disadvantages of all prediction methods.The procedure of the application of this system was introduced in detail.For prediction,the selection of prediction methods is an important and challenging work.The analytic hierarchy process(AHP) was developed for prediction optimization.We applied the newly developed prediction system to several important projects in China,including Hurongxi highway,Jinping II hydropower station,and Kiaochow Bay subsea tunnel.The case studies show that the geological defective features can be successfully detected with good precision and efficiency,and the prediction system is proved to be an effective means to minimize the risks of geological hazards during tunnel construction.Shucai Li Shuchen Li Qingsong Zhang Yiguo Xue Bin Liu Maoxin Su Zhechao Wang Shugang Wang 2010Journal of Rock Mechanics and Geotechnical Engineering2010,2,3:25
203D random Voronoi grain-based models for simulation of brittle rock damage and fabric-guided micro-fracturing显示文摘A grain-based distinct element model featuring three-dimensional(3D) Voronoi tessellations(random poly-crystals) is proposed for simulation of crack damage development in brittle rocks. The grain boundaries in poly-crystal structure produced by Voronoi tessellations can represent flaws in intact rock and allow for numerical replication of crack damage progression through initiation and propagation of micro-fractures along grain boundaries. The Voronoi modelling scheme has been used widely in the past for brittle fracture simulation of rock materials. However the difficulty of generating 3D Voronoi models has limited its application to two-dimensional(2D) codes. The proposed approach is implemented in Neper, an open-source engine for generation of 3D Voronoi grains, to generate block geometry files that can be read directly into 3DEC. A series of Unconfined Compressive Strength(UCS) tests are simulated in3 DEC to verify the proposed methodology for 3D simulation of brittle fractures and to investigate the relationship between each micro-parameter and the model's macro-response. The possibility of numerical replication of the classical U-shape strength curve for anisotropic rocks is also investigated in numerical UCS tests by using complex-shaped(elongated) grains that are cemented to one another along their adjoining sides. A micro-parameter calibration procedure is established for 3D Voronoi models for accurate replication of the mechanical behaviour of isotropic and anisotropic(containing a fabric) rocks.E.Ghazvinian M.S.Diederichs R.Quey 2014Journal of Rock Mechanics and Geotechnical Engineering2014,6,6:24
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