Rock engineering design of post-tensioned anchors fordams e A review
摘要：High-capacity, post-tensioned anchors have found wide-spread use, originally in initial dam design andconstruction, and more recently in the strengthening and rehabilitation of concrete dams to meetmodern design and safety standards. Despite the advances that have been made in rock mechanics androck engineering during the last 80 years in which post-tensioned anchors have been used in dam engineering,some aspects of the rock engineering design of high-capacity rock anchors for dams havechanged relatively little over the last 30 or 40 years. This applies, in particular, to the calculations usuallycarried out to establish the grouted embedment lengths required for deep, post-tensioned anchors.These calculations usually make simplified assumptions about the distribution and values of rockegroutinterface shear strengths, the shape of the volume of rock likely to be involved in uplift failure under theinfluence of a system of post-tensioned anchors, and the mechanism of that failure. The resulting designsare generally conservative. It is concluded that these aspects of the rock engineering design of large, posttensionedrock anchors for dams can be significantly improved by making greater use of modern,comprehensive, numerical analyses in conjunction with three-dimensional （3D） models of the rock massstructure, realistic rock and rock mass properties, and the results of prototype anchor tests in the rockmass concerned. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.Tests and analysis of mechanical behaviours of rock bolt componentsfor China＇s coal mine roadways
摘要：A series of laboratory tests were performed to study the mechanical behaviours of newly developed highstrength rock bolt components, including rebar, thread, plate, and domed washer. The characteristics ofdeformation and damage of each component were presented. The stress distribution of plate and domedwasher was investigated through finite element modelling. The numerical results show that the yieldand tensile strengths of the developed high strength rebar are 33.6%e58.3% and 17.2%e28.7% greaterthan those of the conventional rebar, respectively. The increase in yield strength was higher than that intensile strength, suggesting an increase in yield to tensile strength ratio and a decrease in elongation. It iswell-known that the thread processing may not be of high precision and accuracy as expected, which ischaracterised as rough thread surface, non-identical tooth height, toe stripping, and cracks in the surface.Hardening during thread processing tends to increase the thread yield and tensile strengths. In thispaper, the typical deformation process of arch-shaped plate is classified into five stages. The tested platesexhibited distinct deformation characteristics and bearing capacities due to variations in shape, size,material and presence of washer. It was observed that uneven bottom surface, low bearing arch and largeradius of the transitional arc connecting bearing arch and bottom surface were the major reasons accountingfor low load-bearing capacity of plates. The performance of domed washer has a close relationwith the shape, size, strength, and deformation compatibility with plate. Stress concentration wasobserved on the periphery of the contact surface between domed washer and plate, which is significantlyinfluenced by the strength of domed washer and is considered to be 20%e30% higher than that of plate.Finally, a case study in the Datong coal mining district was presented, and the support pattern and effectof the developed rock bolt were described. 2015 Institute of Rock and Soil Mechanics, Chinese AcadDynamic rock tests using split Hopkinson （Kolsky）bar system e A review
摘要：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 andmuch more challenging than their static counterparts. Dynamic tests are usually conducted using thesplit Hopkinson bar or Kolsky bar systems, which include both split Hopkinson pressure bar （SHPB） andsplit Hopkinson tension bar （SHTB） systems. Significant progress has been made on the quantification ofvarious 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 techniquesfor 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. pulseshaping, momentum-trap and multi-axial loading techniques）. Various measurement techniques for rocktests 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 measurementtechniques 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. dynamicimitation and propagation fracture toughness, dynamic fracture energy and fracture velocity）, and dynamictechniques for studying the influences of temperature and pore water. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.Numerical estimates of the maximum sustainable pore pressure inanticline formations using the tensor based concept of porepressure-stress coupling
摘要：The advanced tensor based concept of pore pressure-stress coupling is used to provide pre-injection analytical estimates of the maximum sustainable pore pressure change, APo for fluid injection sce- narios into generic anticline geometries. The heterogeneous stress distribution for different prevailing stress regimes in combination with the Young＇s modulus （E） contrast between the injection layer and the cap rock and the interbedding friction coefficient, μ, may result in large spatial and directional differences of △Pc. A single value characterizing the cap rock as for horizontal layered injection scenarios is not obtained. It is observed that a higher Young＇s modulus in the cap rock and/or a weak mechanical coupling between layers amplifies the maximum and minimum △Pc values in the valley and limb, respectively. These differences in △Pc imposed by E and μ are further amplified by different stress re- gimes. The more compressional the stress regime is, the larger the differences between the maximum and minimum △Pc values become. The results of this study show that, in general compressional stress regimes yield the largest magnitudes of △Pc and extensional stress regimes provide the lowest values of △Pc for anticline formations. Yet this conclusion has to be considered with care when folded anticline layers are characterized by flexural slip and the friction coefficient between layers is low, i.e. μ = 0.1. For such cases of weak mechanical coupling, △Pc magnitudes may range from 0 MPa to 27 MPa, indicating imminent risk of fault reactivation in the cap rock. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. All rights reserved.Review of methods for predicting in situ volume change movementof expansive soil over time
摘要：The soil movement information over time is required for the design of foundations placed in expansivesoils. This information is also helpful for the assessment of pre-wetting and controlled wetting mitigationalternatives for expansive soils. Several researchers during the past fifteen years have proposed differentmethods for the prediction of the soil movements over time. The available methods can be categorizedinto （i） consolidation theory-based methods, （ii） water content-based methods, and （iii） suction-basedmethods. In this paper, a state-of-the-art of the prediction methods is succinctly summarized. Themethods are critically reviewed in terms of their predictive capacity along with their strengths andlimitations. The review highlights the need for prediction methods that are conceptually simple yetefficient for use in conventional engineering practice for different types of expansive soils. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.Stability analysis of large-scale stope using stage subsequent fillingmining method in Sijiaying iron mine
摘要：To improve mining production capacity, a stage subsequent filling mining （SSFM） method is employedfor Sijiaying iron mine. The height of the stage stope is approximately 100 m. As there are farmlands andvillages on the surface of the mine, the surface deformation should be controlled when the ore is minedout for the purpose of stope stability and minimizing surface subsidence. In this paper, according to thesite-specific geological conditions, the self-stability of the stage-filling body was analyzed, and the failuremechanism of backfilling body was defined. Thus the relationship between the exposed height of fillingbody and the required strength was obtained. Next, the stability of backfilling body and the characteristicsof surface subsidence due to mining of 450 m level were analyzed using physical modeling.Finally, a three-dimensional numerical model was established using FLAC3D, with which the surfacesubsidence and the stability of stope were achieved. The results show that the stope basically remainsstable during the two-step recovery process. The maximum magnitude of the incline is 10.99 mm/m, alittle larger than the permissible value of 10 mm/m, and the horizontal deformation is 5.9 mm/m,approaching the critical value of 6.0 mm/m, suggesting that the mine design is feasible for safety mining. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.Some modifications to the process of discontinuous deformationanalysis
摘要：This paper presents a modified method of discontinuous deformation analysis （DDA）. In the presentedmethod, open-close iteration may not be needed, small penetration is permitted among blocks, andsprings are added between contacting block pairs only when a penetration takes place. The three contactpatterns （i.e. sliding, locking and opening） in original DDA method are not involved, and the recognitionof these contact patterns and treatment of transformation among patterns are not required either,significantly saving the computing time. In a convex to concave contact, there are two candidate entranceedges which may cause uncertainty. In this case, we propose the angle bisector criterion to determine theentrance edge. The spring stiffness is much larger than Young＇s modulus in the original DDA, however wefind that the correct results can still be obtained when it is much smaller than Young＇s modulus. Finally,the penetrations by using penalty method and augmented Lagrangian method are compared. Penetrationof the latter is 1/4 of the former. The range of spring stiffness for the latter is wider than the former,being 0.01e1 of the former. Both methods can lead to correct contact forces. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.Modeling and numerical analysis of granite rock specimen undermechanical loading and fire
摘要：The effect of ISO 834 fire on the mechanical properties of granite rock specimen submitted to uniaxialloading is numerically investigated. Based on Newton＇s second law, the rate-equation model of graniterock specimen under mechanical load and fire is established. The effect of heat treatment on the mechanicalperformance of granite is analyzed at the center and the ends of specimen. At the free end ofgranite rock specimen, it is shown that from 20 C to 500 C, the internal stress and internal strain areweak; whereas above 500 C, they start to increase rapidly, announcing the imminent collapse. At thecenter of specimen, the analysis of the internal stress and internal strain reveals that the fire reduces themechanical performance of granite significantly. Moreover, it is found that after 3 min of exposure to fire,the mechanical energy necessary to fragment the granite can be reduced up to 80%. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.
