Liu, G. F. (State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences) | Feng, X. T. (State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences) | Feng, G. L. (State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences) | Zhang, Y. J. (State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences) | Zhao, Z. N. (Northeastern University) | Chen, D. F. (Northeastern University)
Based on the background of deep-buried tunnels project in Jinping II hydropower station, focusing on the prominent problems, such as casualties, equipment and facility damage caused by rockburst hazard, this paper attempts to provide a security risk assessment methodology during deep-buried tunnel excavation by drilling and blasting method. The results of previous research regarding the prediction of rockburst by means of real-time microseismic monitoring technique, in combination with the relevant statistical data from a large number of rockburst samples, have been used to propose the implementation procedures of dynamic risk assessment of rockburst during tunnel construction, which involves identifying and dividing risk region, analyzing the probability of risk, estimating the consequences of risk, determining the level of risk, evaluating and controlling the risk. Finally, one case study is given of the use of this method in the process of tunnel construction.
In recent years, casualties, equipment and facility damage caused by rockburst have occurred more frequently, which requires our urgent attention. Can we accurately predict its likelihood before it occurs? How to anticipate the consequences of a possible rockburst? What measures should we take to avoid or minimize the occurrence of rockburst, and its negative consequences on workers, equipments, and facilities to an acceptable level? The problems associated with rockburst have attracted a great deal of attention of late, and although researches have been focusing on mechanism, prediction and control measures for rockburst, this still can’t answer all of the above questions. Actually, this comes down to the research of security risk assessment. Since the 1970s, many scholars (Einstein, 1974; 1996; Schubert, 2011; Sousa et al., 2012; Huang, 2006) have made great contributions to the field of risk assessment in tunnel engineering. However, previous research mainly focused on road tunnels, subway tunnels and other shallow-buried tunnels. As for rockburst in deep-buried tunnels, the studies on risk assessment are quite few. Because of the specific peculiarities, such as concealed geologic conditions and high geostress, deep-buried tunnels are quite different from conventional tunnels. Present methods of risk assessment in tunnel engineering can not necessarily be applied to rockburst.
Li, Q. P. (State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, The Chinese Academy of Sciences) | Chen, B. R. (State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, The Chinese Academy of Sciences)
The micro-seismic monitoring work during linear excavation process of deep tunnel has the following characteristics: many working faces are constructed simultaneously; the sensor arrays are located in the rear of the working face; the vertical direction coordinate gap of all sensors is small. Due to the above characteristics, traditional Geiger’s location method cannot work out stable solution. With the micro-seismic monitoring work of Jinping II hydropower station, this article forms Newton second order method and Newton downhill method to improve former method. The rock-burst location results with three methods are proposed and their calculation abilities are compared. The results show that computational accuracy of the second method is influenced by initial value and the third method has the global convergence; At last, the last two methods together are adopted for source location of five rock-bursts. The conclusion indicates that that improves the accuracy and stability of algorithm convergence.
With deep exploitation of mineral resources and development of underground space, there are more and more underground engineering with increasing rock-burst accidents caused by high geostress . Therefore effective monitoring and prediction for rock-burst is one of the most important approaches to guarantee the safety of deep geotechnical engineering and micro-seismic monitoring technology plays a pivotal role in it for it can effectively monitor the position of rock fracture  and begin to be used in some fields like mine safety monitoring and hydropower underground engineering.
3D position of micro-seismic source is an important parameter in the monitoring research, and how to locate the seismic source accuracy and efficiency has always been an important content. Most of the location methods are extended from earthquake location, such as classic Geiger method, relative positioning method, double residual method, Bayesian method  . These methods have greatly promoted the progress of the study on micro-seismic source location.
In the field of mine micro-seismic monitoring, Chen  applies particle swarm algorithm to improve the positioning accuracy; Lin  utilizes linear positioning algorithm to determine the iterative initial value and employs Geiger method for accurate position, which receives the desired effect; Dong  combines epicenter coordinates with wave velocity as unknown, which effectively avoids the influence of inaccurate velocity. The studies above is all belong to mine micro-seismic monitoring field, however, little research is known on source location during linear tunnel excavation process.
Xu, Jiangbo (Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences) | Wu, Faquan (Key Laboratory of Engineering Geomechanics, Institute of Geology and Geophysics, Chinese Academy of Sciences) | Zheng, Yingren (Department of Civil Engineering, Logistical Engineering University)
In recent years, embedded anti-slide pile was applied widely in the slope protection, and it becomes the major method in this field. So far, the research was well developed under the static situation, but the dynamic situation. In this article, according to the dynamic strength reduction method and utilization of finite difference soft ware (FLAC), a new embedded anti-slide pile anti-seismic design method was put up. Comparing the internal force value of pile before and after earthquake effects, the bigger value was adopted to be the value which is designed internal anti-seismic value, as well as the internal force distribution of the pile was analyzed. After the calculation and analysis of the particular slope, the result shows that: the embedded anti-slide pile not only can protect the slope under the static situation, but also can satisfy the requirements of the anti-seismic design.
In landslide support, as a newand economic reinforcement measure, embedded anti-slide pile can save a lot of engineering materials, and reduce the project’s cost. However, the design of majority embedded anti-slide pile is based on experience or some rough calculation. It is great risk, but also difficult to give full play to the potential ability of the embedded anti-slide pile, therefore the pile hasn’t been widely used. In recent years, Zheng et al. (2002) take the finite element strength reduction method, and put forward the systematic calculation and design method of the embedded antislide pile. This method can accurately calculate the length, thrust, resistance force and internal force of the buried pile. They also have conducted the large-scale physical model test study on the embedded anti-slide pile (Lei 2006; Song et al. 2007), combined with numerical simulation to verify the accuracy of theoretical calculation, and this method has been used in some engineering. But in these projects, the dynamic response to seismic action hasn’t been considered, or some projects use rough pseudo-static method, so the research on the seismic design of the anti-slide pile is very necessary.
In this paper, base on the dynamic strength reduction method which has been proposed by Zheng Yingren, we put forward the dynamic calculation and design method on embedded anti-slide pile, this method can fully consider the dynamic effect to make the seismic design is more scientific, reasonable and economic.
Xie, N. (Faculty of Engineering, China University of Geosciences) | Yang, J. B. (Key Laboratory of Earthquake Geodesy, Institute of Seismology, CEA) | Tang, H. M. (Wuhan Institute of Seismologic Engineering)
This paper aims to take a review on the modeling of damage in quasi-brittle rocks based upon continuum micromechanics. The basic idea of continuum micromechanics is a representation of brittle porous rocks as a material with distributed microcracks. With a crack density parameter identified as the governing state variable for the description of damage, methods of continuum micromechanics, namely the Eshelby-based homogenization schemes, are used to obtain macroscopic quantities such as elastic stiffness tensor and stress and strain, respectively. A thermodynamics approach is finally employed to obtain a macroscopic elastoplactic damage model, in which the frictional dissipation on the lips of closed cracks and its coupling with damage can be treated. Overall, the approach is to substitute constitutive parameters, which have been defined a priori on macroscopic level, by micromechanically motivated parameters, which have more sound physical interpretations. Discussions on the future work related to micromechanics-based damage modeling are also carried out.
As a natural composite material, the formation of rocks can be treated as a multiphase and multiscale material system. The most complicated phase in natural composite materials is the porosity, i.e. the space left in between the different solid phases at various scales, ranging from interlayer spaces in between minerals filled by a few water molecules, to the macropore space in between microstructural units of the material in the micrometer to millimeter range (Coussy, 2004). This porosity is the key to understanding and predicting macroscopic behavior of the material, ranging from diffusive or advective transport properties to stiffness, strength and fracture behavior (Dormieux et al., 2006a).
The breakthrough with pioneering work that relates macroscopic laws to microstructural properties was achieved in the 1970s. Auriault and Sanchez-Palencia (1977) were the first to develop appropriate averaging schemes for poroelastic materials under the assumption that the microstructure of porous material has a periodic pattern. Since these early works, various methods have been applied in order to determine the macroscopic behavior of a saturated porous medium starting from the microscopic scale. A reformulation of the equations of anisotropic poroelasticity was proposed by Thompson and Willis (1991). The relationships between the macroscopic poroelastic constants and the properties of porous medium constituents at microscopic level have been established.
This paper provides a brief summary of a continuous research programme by the authors since 2004, and highlights the research approach, achievements and outstanding issues for conceptual understanding, laboratory testing and mathematical modeling of the coupled stress-shear-fluid flow-solute transport processes of rock fractures. The focuses are put on stress and shear induced fluid flow anisotropy, transport pass channeling, and impact of considering different retardation mechanisms in single fractures of crystalline rocks, typically granites, due to its importance for the performance and safety assessments of geological radioactive waste disposal projects.
Rocks are natural geological materials containing fractures of different origins, sizes, mineral fillings, weathering degrees, orientations, termination patterns, thickness and shapes, and especially surface roughness features. In addition, rocks in-situ are under stress, caused by dynamicmovements in the upper crust of the Earth, such as tectonic plate movements, earthquakes, land uplifting/subsidence, glaciation cycles and tides, in addition to gravity. A rock mass is also a fractured porous medium containing fluids in either liquid or gas phases (e.g. water, oil, natural gases and air), under complex in-situ conditions of stresses, heating or cooling, freezing or thawing, fluid pressures, and complicated geochemical reactions, with connected fractures most often serve as the major energy and mass transport pathways and most active areas of geochemical reactions, especially for fractured hard crystalline rocks. This is the reason why the coupled thermal (T), hydraulic (H), mechanical (M) and chemical (C) processes is an issue of importance in the field of rock mechanics.
The terms “discontinuity” and “fracture” are used interchangeably in the rock mechanics literature. The term “fracture” is adopted throughout this paper as a collective term for all types of natural or artificial discontinuities such as faults, joints, dykes, fracture zones and other types of weakness surfaces or interfaces, unless specifically stated otherwise. The rock fractures are usually not just open voids with fresh and smooth surfaces. Their surfaces (or walls) are often rough, weathered and fully or partially filled with precipitated minerals, and their relative positions are often modified by geological history and loading conditions, such as opening, closing, faulting or shearing, with large or small relative displacements. The complexity in the surface topography makes understanding and quantitative representation of the physical-chemical behavior and rock fracture properties difficult issues.
This paper discusses the purposes of, and the processes involved in, the several types of technical audit and/or review of aspects of rock engineering projects carried out in an international consulting practice. The reviews discussed relate to the investigation, design and construction of surface and underground rock engineering projects in the civil engineering, mining and energy resource industries. Eleven categories of review carried out in the authors’ consulting practice are identified and discussed. Some, but not all, of these types of review are similar to the technical audits detailed by Hudson & Feng (2010) and Feng & Hudson (2011) as part of the work of the ISRM’s Commission on Rock Engineering Design Methodology. Case examples are given of the authors’ recent experience in carrying out three of the 11 types of rock engineering review identified.
This paper discusses the purposes of, and the processes involved in, the several types of technical audit and/or review of aspects of rock engineering projects carried out in an international consulting practice.The reviews discussed relate to the investigation, design and construction of surface and underground rock engineering projects in the civil engineering, mining and energy resource industries.
The impetus for preparing this paper was provided by the seminal publications on the technical auditing of rock mechanics modelling and rock engineering design by Hudson & Feng (2010) and Feng & Hudson (2011) arising out of their work for the Commission on Rock Engineering Design Methodology of the International Society for Rock Mechanics (ISRM) in the period 2007–2011. The several types of technical review customarily carried out by the authors include reviews similar to the technical audits detailed by Hudson&Feng (2010) and Feng&Hudson (2011), but they sometimes have different purposes, emphases and reporting requirements.
Progresses in understanding, analysis and control of rock slope movements have been the result of interdisciplinary efforts involving engineering geologists and rock engineers. In addition to rock engineering methodologies, the input from engineering geology is absolutely a fundamental to any rock slope design. This paper aims to emphasize the importance of harmonizing engineering geology with rock engineering on stability of rock slopes. Main engineering geological factors featured in the design and construction of rock slopes, role of engineering geological model and their combination with the stability analysis methods used in rock slope engineering are briefly discussed with their advantages and limitations, and finally current and near future needs related to stability of rock slopes are also described.
The construction, design, remediation and maintenance of rock slopes have always been an important area of geo-engineering. Particularly, in the last two decades, increasing demand for ultra deep open pits and large civil engineering constructions in rocks such as expressways, highways, railways and dams, and the effects of earthquake-triggered slope failures on settlements located in mountainous regions resulted in more attention to be paid to rock slope stability. Progresses in understanding, analysis and control of rock slope movements have been the result of interdisciplinary efforts mainly involving engineering geologists and rock engineers.>/p>
IAEG states that engineering geology is the discipline of applying geologic data, techniques and principles to the study of rock and soil materials, surface and subsurface fluids, and interactions of introduced materials and processes with the environment so that geologic factors are adequately recognized, interpreted and presented for use in engineering and related practice (Keaton 2010). The engineering geologist, as a predictor, translates the scientific facts, observed or measured, into engineering data to identify areas of significant physical constraint that will adversely affect the design, construction and maintenance of any intended engineering project (Mathewson 1981) (Figure 1).
Akutagawa, S. (Department of civil engineering, Graduate School of Engineering, Kobe University) | Zhang, H. (Department of civil engineering, Graduate School of Engineering, Kobe University) | Terashima, M. (Department of civil engineering, Graduate School of Engineering, Kobe University) | Tsujimura, K. (SK Laboratory Co., Ltd.)
There is an urgent need of new strategy for the monitoring of ground movement ahead of mountain tunnel face to improve the safety management. A new sensor is under development for the monitoring based on the concept of “On Site Visualization”. This method is different from the conventional field measurement techniques in that deformation is measured on site and visualized by different colors of light in real-time. Since this method makes use of optical fibers as the light propagation medium, it could keep on visualizing the displacement of measuring points even if its front part is cut as needed during excavation. The paper presents some laboratory experiments to demonstrate the applicability of this scheme. By doing this, it is found possible to monitor the ground deformation by the proposed sensor. Finally, some work in future is discussed briefly.
In the field of mountain tunneling, the frequency of accidents remains a considerable level due to the collapse or water inflow at the tunneling face during construction, though many efforts have been made to ensure the stability of tunneling face. Monitoring is thought to take an important part in tunneling and other disaster risk reduction project. However, because of the problem of cost and operability of exiting approaches, the monitoring measures cannot be taken to cover all the places of risk.
Recently, a new concept called “On Site Visualization” (S. Akutagawa et al. 2011b) has been proposed originally in Japan to provide a new scheme of monitoring for structures on site. It is capable of monitoring the displacement or force, and visually outputting the measurement results in real-time for workers and all concerned. It uses the color of light as a key technology to demonstrate the risk condition of construction directly. Based on this concept, a series of sensors with low cost and power consumption are developed or under development for monitoring and visualization on site, some of which have already been employed in practice. Since the new sensors could provide not only the basic monitoring but also the function of visualization of result at low cost, it makes possible to carry out monitoring in wider areas to improve the risk management practices.
In this paper, a new sensor for monitoring ground deformation ahead of mountain tunneling face is introduced. The sensor consists of plastic optical fiber, color filter film, sliding stopper and so on, using LED as the light source. Laboratory experiments were conducted to verify the applicability of the measurement scheme. By doing the primary experiments, it is found possible to monitor and visually present the ground movement by this sensor.
Based on a three-dimensional non-linear constitutive model, this study investigates the anisotropic deformation of a tunnel excavated in jointed rock masses and associate supporting effects of rockbolts. Using a numerical model capable of describing the influence of mechanical behavior of intact rock, the spatial configuration of joint sets, and mechanical behavior of the joint plane on the non-linear behavior of a rock mass, this manuscript reveals the joint-induced anisotropy in failure zone and deformation surrounding a tunnel. The support effects of a rockbolt are generally limited. However, when the rockbolt is pre-stressed and acts perpendicular to a joint plane, the shear displacement and associated dilation of the plane is constrained. And the joint sliding failure caused by tunnel excavation can be reduced. The rockbolt provides a beaming effect. Such an effect is significant in locations where the joint planes parallel to tunnel wall and influenced by the numbers of joint sets and joint strength.
A rockbolt is an innovative support element in modern tunneling, providing active pre-stress support and associated constraining effects to sustain a potential falling rock wedge and to minimize shear dilation on fractural planes, which benefits the limitation on the development of excavation disturbance zone (Spang& Egger, 1990; Huang et al., 2002; Bobeta & Einsteinb, 2011). However, conventional mechanical models and numerical modeling generally simplify rock masses as homogeneous isotropic medias and stipulate the behavior after excavating a tunnel for support design, which disregard the discontinuity induced anisotropic behavior in rock strength and deformation, neither insufficiently access the effect of tunnel supports. The support effects of modern tunneling have not beenwell evaluated yet.
Focusing on a rockbolt, this study aims to elucidate its diverse mechanism for supporting a rock tunnel using numerical approach. The two-dimensional numerical implementation, which embedding the three-dimensional non-linear constitutive model for a rock mass containing ubiquitous joint sets, is utilized. The constitutive model (Wang & Huang, 2009) takes the mechanical behavior of intact rock, the orientations of joint sets, and the mechanical behavior of joint planes into account, and therefore the adopted numerical code is capable of describing complete stress-strain relationship and strength and deformability anisotropies of rock masses induced by joint sets. Thus, the rock support effects can be quantitatively analyzed and well elucidated.
Salt caverns are utilized widely as natural gas storage and compressed air energy storage because of rheology and low-permeability of salt. For both natural gas storage or energy storage, gas injection and gas withdrawal are carried on alternately, two cycles one year for natural gas storage while one cycle every day for compressed air energy storage. For investigation of mechanical characteristics of rock salt under injection and withdrawal cycles, triaxial cyclic loading tests were conducted using a MTS test system. Linear relationships between stress and strain under unloading and reloading were observed. The linear character of the stress-strain response during reloading and unloading is more apparent at an increased confining pressure. Confining pressure reduces the difference of deformation modulus between unloading and reloading. The constitutive relationship for loading and unloading was constructed and proved by fatigue testes.
Because of the rheology, low-permeability, and damage recovery of rock salt, salt caverns were widely used as natural gas storage and compressed air energy storage. The creep property of salt rock has been studied in many view points for several decades (Hunsche, 1984, Cristescu, 1996, Hampel, 1996). Several constitutive models have been constructed (Cristescu, 1993, Chan, 1996, Hou, 2003). Permeability values derived by laboratory measurements on undisturbed rock salt samples are generally less than 10-20m2 (Schulze, 2001). Even on a large scale in the field, measured permeability is less than 10-18m2 (Berest, 1996).
Salt caverns have been used for gas storage for several decades in Europe and America. Gas storage in Germany has a history of more than 35 years, and more than 106m3 volume of storage has been designed and constructed(Lux, 2009).
In China, underground gas storage (UGS) in rock salt is still at the primary stage. Jintan UGS,which provides service forWest-East Pipeline Project I, started gas injection in the end of 2007, and about 60 salt caverns (2.5×105 m3 volume per cavern) are planning to constructed in the future to supply about 1.8×109m3 volume of natural gas. Till 2013, there are 10 salt caverns constructed and 20 salt caverns under construction. One salt cavern is leaching out by now at Yunying UGS, which is to provide service for West-East Pipeline Project II, and will have 15 salt caverns (1.0×105 m3 volume per cavern) in the future. The working volume ofYunying UGS is 0.6×109 m3 or so. Qianjiang UGS, which is intended to service for Sichuan-East Pipeline Project, is in the leaching stage. Qianjiang gas storage is also the deepest rock salt underground storage in China, which is about 1 900~2 080m in depth.