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| 1 | 固液耦合模式下含断层缺陷煤层回采诱发底板损伤及断层活化突水机制研究显示文摘针对具体地质条件,以现场试验数据为基础,采用相似材料试验及数值模拟相结合的分析方法,对含断层缺陷煤层回采过程中底板损伤破坏及断层活化规律进行研究,研究得出:采用内径不同的水管能够很好地反映底板岩层渗透性的空间差异性,通过采用调节注水管水柱高度的方式可以控制水压以满足设计要求;煤层埋深、承压水水压及断层落差越大越易突水,断层防水煤柱宽度越大越不易突水;通过试验及模拟计算再现了不同因素影响下煤层回采过程中底板采动裂隙形成、断层活化到突水通道形成的全过程,揭示了含断层构造底板突水通道的形成机制;研究结果对承压水上含断层缺陷煤层回采时防水煤柱的留设具有重要的参考价值。 | 张培森 颜伟 张文泉 SHEN Baotang 王浩 | 2016 | 岩土工程学报2016，38，5： | 25 |
| 2 | Investigation of overburden behaviour for grout injection to control mine subsidence显示文摘This paper describes a field and numerical investigation of the overburden strata response to underground longwall mining, focusing on overburden strata movements and stress concentrations.Subsidence related high stress concentrations are believed to have caused damage to river beds in the Illawarra region, Australia. In the field study, extensometers, stressmeters and piezometers were installed in the overburden strata of a longwall panel at West Cliff Colliery. During longwall mining, a total of1000 mm tensile deformation was recorded in the overburden strata and as a result bed separation and gaps were formed. Bed separation was observed to start in the roof of the mining seam and gradually propagate toward the surface as the longwall face advanced. A substantial increase in the near-surface horizontal stresses was recorded before the longwall face reached the monitored locations. The stresses continued to increase as mining advanced and they reached a peak at about 200 m behind the longwall face. A numerical modelling study identified that the angle of breakage(i.e., the angle of the boundary of caved zone) behind the longwall face and over the goaf was 22–25° from vertical direction. This is consistent with the monitoring results showing the high gradient of stresses and strains on the surface150–320 m behind the mining face. | Shen Baotang Poulsen Brett | 2014 | International Journal of Mining Science and Technology2014，24，3： | 8 |
| 3 | An approximate nonlinear modified Mohr-Coulomb shear strength criterion with critical state for intact rocks显示文摘In this paper, the Mohr-Coulomb shear strength criterion is modified by mobilising the cohesion and internal friction angle with normal stress, in order to capture the nonlinearity and critical state concept for intact rocks reported in the literature. The mathematical expression for the strength is the same as the classical form, but the terms of cohesion and internal friction angle depend on the normal stress now,leading to a nonlinear relationship between the strength and normal stress. It covers both the tension and compression regions with different expressions for cohesion and internal friction angle. The strengths from the two regions join continuously at the transition of zero normal stress. The part in the compression region approximately satisfies the conditions of critical state, where the maximum shear strength is reached. Due to the nonlinearity, the classical simple relationship between the parameters of cohesion, internal friction angle and uniaxial compressive strength from the linear Mohr-Coulomb criterion does not hold anymore. The equation for determining one of the three parameters in terms of the other two is supplied. This equation is nonlinear and thus a nonlinear equation solver is needed. For simplicity, the classical linear relationship is used as a local approximation. The approximate modified Mohr-Coulomb criterion has been implemented in a fracture mechanics based numerical code FRACOD,and an example case of deep tunnel failure is presented to demonstrate the difference between the original and modified Mohr-Coulomb criteria. It is shown that the nonlinear modified Mohr-Coulomb criterion predicts somewhat deeper and more intensive fracturing regions in the surrounding rock mass than the original linear Mohr-Coulomb criterion. A more comprehensive piecewise nonlinear shear strength criterion is also included in Appendix B for those readers who are interested. It covers the tensile, compressive, brittle-ductile behaviour transition and the critical state, and gives smooth transitions. | Baotang Shen Jingyu Shi Nick Barton | 2018 | Journal of Rock Mechanics and Geotechnical Engineering2018，10，4： | 6 |
| 4 | Modelling fracture propagation and failure in a rock pillar under mechanical and thermal loadings显示文摘The spPillar Stability Experiment (APSE) was conducted to study the rock mass response in a heated rock pillar between two large boreholes. This paper summarizes the back calculations of the APSE using a two-dimensional (2D) fracture propagation code FRACOD. To be able to model all the loading phases of the APSE, including the thermal loading, the code was improved in several ways. A sequential excavation function was developed to model promptly the stepwise changing loading geometry. Prior to the mod-elling, short-term compressive strength test models were set up aiming to reproduce the stress-strain behaviour observed for the sp diorite in laboratory. These models simulate both the axial and lateral strains of radial-controlled laboratory tests. The volumetric strain was calculated from the simulations and compared with the laboratory results. The pillar models include vertical and horizontal 2D models from where the stress in the pillar wall was investigated. The vertical model assesses the stability of the experimental rock volume and suggests the resultant stress below the tunnel floor in the pillar area. The horizontal model considers cross-sections of the pillar between the two large boreholes. The horizontal model is used to simulate the evolution of the stress in the rock mass during the excavation of the boreholes and during and the heating phase to give an estimation of the spalling strength. The modelling results suggest that the excavation-induced stresses will cause slight fracturing in the pillar walls, if the strength of the APSE pillar is set to about 123 MPa. Fracture propagation driven by thermal loading leads to minor spalling. The thermal evolution, elastic behaviour and brittle failure observed in the experiment are well reflected by the models. | Mikael Rinne Baotang Shen Tobias Backers | 2013 | Journal of Rock Mechanics and Geotechnical Engineering2013，5，1： | 6 |
| 5 | Risk of shear failure and extensional failure around over-stressed excavations in brittle rock显示文摘The authors investigate the failure modes surrounding over-stressed tunnels in rock.Three lines of investigation are employed:failure in over-stressed three-dimensional(3D) models of tunnels bored under 3D stress,failure modes in two-dimensional(2D) numerical simulations of 1000 m and 2000 m deep tunnels using FRACOD,both in intact rock and in rock masses with one or two joint sets,and finally,observations in TBM(tunnel boring machine) tunnels in hard and medium hard massive rocks.The reason for 'stress-induced' failure to initiate,when the assumed maximum tangential stress is approximately(0.4-0.5)σ_c(UCS,uniaxial compressive strength) in massive rock,is now known to be due to exceedance of a critical extensional strain which is generated by a Poisson's ratio effect.However,because similar 'stress/strength' failure limits are found in mining,nuclear waste research excavations,and deep road tunnels in Norway,one is easily misled into thinking of compressive stress induced failure.Because of this,the empirical SRF(stress reduction factor in the Q-system) is set to accelerate as the estimated ratio σ_(θmax)/σ_c >> 0.4.In mining,similar 'stress/strength' ratios are used to suggest depth of break-out.The reality behind the fracture initiation stress/strength ratio of '0.4' is actually because of combinations of familiar tensile and compressive strength ratios(such as 10) with Poisson's ratio(say0.25).We exceed the extensional strain limits and start to see acoustic emission(AE) when tangential stress σθ≈ 0.4σc,due to simple arithmetic.The combination of 2D theoretical FRACOD models and actual tunnelling suggests frequent initiation of failure by 'stable' extensional strain fracturing,but propagation in 'unstable' and therefore dynamic shearing.In the case of very deep tunnels(and 3D physical simulations),compressive stresses may be too high for extensional strain fracturing,and shearing will dominate,both ahead of the face and following the face.When shallower,the concept of 'extensional strain initiation but propagation' in shear is suggested.The various failure modes are richly illustrated,and the inability of conventional continuum modelling is emphasized,unless cohesion weakening and friction mobilization at different strain levels are used to reach a pseudo state of yield,but still considering a continuum. | Nick Barton Baotang Shen | 2017 | Journal of Rock Mechanics and Geotechnical Engineering2017，9，2： | 5 |
| 6 | 3D morphology and formation mechanism of fractures developed by true triaxial stress显示文摘As main part of underground rock mass,the three-dimensional(3D)morphology of natural fractures plays an important role in rock mass stability.Based on previous studies on 3D morphology,this study probes into the law and mechanism regarding the influence of the confining pressure constraints on 3D morphological features of natural fractures.First,fracture surfaces were obtained by true triaxial compression test and 3D laser scanning.Then 3D morphological parameters of fractures were calculated by using Grasselli’s model.The results show that the failure mode of granites developed by true triaxial stress can be categorized into tension failure and shear failure.Based on the spatial position of fractures,they can be divided into tension fracture surface,S-1 shear fracture surface,and S-2 shear fracture surface.Micro-failure of the tension fracture surface is dominated by mainly intergranular fracture;the maximum height of asperities on the fracture surface and the 3D roughness of fracture surfaces are influenced by σ_(3) only and they are greater than those of shear fracture surfaces,a lower overall uniformity than tension fracture surface.S-1 shear fracture surface and S-2 shear fracture surface are dominated by intragranular and intergranular coupling fracture.The maximum height of asperities on the fracture surface and 3D roughness of fracture surface are affected by σ_(1),σ_(2),and σ_(3).With the increase of σ_(2) or σ_(3),the cutting off of asperities on the fracture surface becomes more common,the maximum height of asperities and 3D roughness of fracture surface further decrease,and the overall uniformity gets further improved.The experimental results are favorable for selecting technical parameters of enhanced geothermal development and the safety of underground mine engineering. | Bing Chen Baotang Shen Shichuan Zhang Yangyang Li Haiyang Jiang | 2022 | International Journal of Mining Science and Technology2022，32，6： | 4 |
| 7 | Gvomechanics and highwall mining显示文摘 | Baotang Shen Mary Duncan fama | 2001 | World Coal2001，1，2： | 1 |
| 8 | Remediation and monitoring of abandoned mines显示文摘paper describes a recent study on using fly ash for backfilling abandoned room and pillar mines.Detailed investigations on fly ash properties such as the strength and stiffness of settled fly ash, flowability of fly ash grout, as well as chemistry and environmental aspects of fly ash backfill have been undertaken in the laboratory. Numerical modelling was also conducted to quantify the effects of fly ash backfill on the stability of underground pillars. The laboratory tests showed that with a solid concentration of approximate 50%, fly ash grout has an excellent flowability and very low viscosity. It is capable of penetrating and filling almost any voids underground if designed properly and settling as a reasonably stiff solid to provide support to the pillars. Several different types of strength tests proved that a consolidated fly ash should exhibit a friction angle above 42°. 3D numerical modelling on interaction between fly ash backfill and underground pillars has shown that fly ash backfill to 90% roadway height can raise the factor of safety(Fo S) of a marginally stable area to above 1.6, which is the number often used in rock engineering design for long term stability. Chemistry and leachate analysis of representative fly ash samples from a local power station showed that the elemental concentrations in the fly ash solid sample are lower than the allowed contaminant threshold and specific contaminant concentration levels. Geotechnical monitoring in the high risk areas of an abandoned mine has been carried out as part of the risk management and control for potential subsidence. The monitoring has been very helpful in understanding the ground behaviour around the abandoned mine which can provide timely information to the parties concerned in order to make correct decisions to control the subsidence risk. | Shen Baotang Brett Poulsen Luo Xun Qin Johnny Ramesh Thiruvenkatachari Duan Yi | 2017 | International Journal of Mining Science and Technology2017，27，5： | 1 |
| 9 | Field investigation of long-term bearing capacity of strip coal pillars显示文摘 | Shao-jie Chen Wei-jia Guo Hui Zhou Baotang Shen Jiang-bo Liu | 2014 | International Journal of Rock Mechanics and Mining Sciences2014，，： | 1 |
| 10 | Geomechanics and Highwall Mining显示文摘 | Baotang Shen Mary Duncan Fama | 2001 | World Coal2001，1，2： | 1 |
| 11 | Effect of faulting on coal burst——A numerical modelling study显示文摘Coal burst occurrence on roadways has always been a major concern in deep underground coal mines,especially under complex geological conditions. To evaluate the effect of faulting on coal burst, the stress concentration in the vicinity a reverse fault was analysed considering the geological history of the fault formation where high horizontal stresses led to the initiation and propagation of the reverse fault.Various in situ stresses and mechanical parameters of the fault, including the ratio of horizontal stress to vertical stress were used to analyse the state of fault. Numerical modelling was conducted using two and three dimensional distinct element models(UDEC and 3 DEC) based on a geotechnical conditions of an Australian underground coal mine. The formation process of reverse fault was simulated to evaluate the stress characteristics in the coal seam and the immediate roof and floor near the fault. The results show that, both the horizontal and vertical stress in footwall were higher than those in hanging wall after the formation of the reverse fault. The stress condition near fault was complicated due to complex geology in the coal measures, and the vertical stress peaked in the footwall at a distance of about 160 m from the fault. When a roadway was excavated, stress concentration occurred at both the roadway face and ribs, which reached as high as 38 MPa in the ribs at a depth of 500 m. This will significantly elevate the risk of dynamic instability of the roadway such as coal burst. The stress concentration zone in the footwall can be considered as a hazardous zone near the reverse fault. This study provides a general reference for analysis of roadway stability affected by faults. | Lu Chen Baotang Shen Bongani Dlamini | 2018 | International Journal of Mining Science and Technology2018，28，5： | 1 |
| 12 | Shear behavior of intact granite under thermo-mechanical coupling and three-dimensional morphology of shear-formed fractures显示文摘The shear failure of intact rock under thermo-mechanical(TM)coupling conditions is common,such as in enhanced geothermal mining and deep mine construction.Under the effect of a continuous engineering disturbance,shear-formed fractures are prone to secondary instability,posing a severe threat to deep engineering.Although numerous studies regarding three-dimensional(3D)morphologies of fracture surfaces have been conducted,the understanding of shear-formed fractures under TM coupling conditions is limited.In this study,direct shear tests of intact granite under various TM coupling conditions were conducted,followed by 3D laser scanning tests of shear-formed fractures.Test results demonstrated that the peak shear strength of intact granite is positively correlated with the normal stress,whereas it is negatively correlated with the temperature.The internal friction angle and cohesion of intact granite significantly decrease with an increase in the temperature.The anisotropy,roughness value,and height of the asperities on the fracture surfaces are reduced as the normal stress increases,whereas their variation trends are the opposite as the temperature increases.The macroscopic failure mode of intact granite under TM coupling conditions is dominated by mixed tensileeshear and shear failures.As the normal stress increases,intragranular fractures are developed ranging from a local to a global distribution,and the macroscopic failure mode of intact granite changes from mixed tensileeshear to shear failure.Finally,3D morphological characteristics of the asperities on the shear-formed fracture surfaces were analyzed,and a quadrangular pyramid conceptual model representing these asperities was proposed and sufficiently verified. | Bing Chen Baotang Shen Haiyang Jiang | 2023 | Journal of Rock Mechanics and Geotechnical Engineering2023，15，3： | 1 |
| 13 | Mining-induced strata stress changes, fractures and gas flow dynamics in multi-seam longwall mining显示文摘 | Hua Guo Liang Yuan Baotang Shen Qingdong Qu Junhua Xue | 2012 | International Journal of Rock Mechanics and Mining Sciences2012，，： | 1 |
| 14 | Simulation of the interactions between hydraulic and natural fractures using a fracture mechanics approach显示文摘HYDROCK method aims to store thermal energy in the rock mass using hydraulically propagated fracture planes.The hydraulic fractures can interact with the pre-existing natural fractures resulting in a complex fracture network,which can influence the storage performance.This study investigates the interactions between hydraulic and natural fractures using a fracture mechanics approach.The new functionality of the fracture mechanics modelling code FRACOD that enables crossing of hydraulically driven fracture by a pre-existing fracture is presented.A series of two-dimensional numerical models is prepared to simulate the interaction at different approach angles in granitic rock of low permeability.It is demonstrated that multiple interaction mechanisms can be simulated using the fracture mechanics approach.The numerical results are in agreement with the modified Renshaw and Pollard analytical criterion for fracture crossing.The results show that for large approach angles,the hydraulic fracture crosses the natural fracture,whereas for small approach angles,the hydraulic fracture activates the natural fracture and the wing-shaped tensile fractures are propagated from its tips.Thus,the presence of fractures with low dip angles can lead to the growth of more complex fracture network that could impair the thermal performance of the HYDROCK method. | Mateusz Janiszewski Baotang Shen Mikael Rinne | 2019 | Journal of Rock Mechanics and Geotechnical Engineering2019，11，6： | 0 |
| 15 | Simulation of Supercritical Carbon Dioxide Fracturing in Shale Gas Reservoir显示文摘In order to fracture shale gas reservoir with carbon dioxide as the working fluid,laboratory experiments were firstly conducted to measure the influence of carbon dioxide immersion on shale rock's properties,and then the coupling mechanism between stress and seepage during hydraulic fracturing was simulated based on cohesive zone model.The fracturing ability of carbon dioxide and water was also compared under the same working conditions,and finally sensitivity analysis(including elastic modulus of shale,filtration coefficient,pump rate and viscosity of carbon dioxide)were conducted based on field application.The results show that,the elastic modulus of shale increased by 32.2%,the Poisson's ratio decreased by 40.3%and the compressive strength decreases by 22.9%after geothermal reaction with carbon dioxide under 30 MPa and 335.15 K for 2 hours.Compared with water fracturing,carbon dioxide fracturing induces longer fracture(increased by 25.3%)and narrower fracture(decreased to 40.8%).The fracture tends to get longer and narrower with increasing elastic modulus of shale.As filtration coefficient increases,the maximum width of fracture decreases significantly,whereas the length changes little.Both the length and maximum width of fracture increase with increasing pump rate,however the changing rate of length tends to decrease.The influence of viscosity of carbon dioxide on both fracture width and length is negligible,which validates the stable feasibility of carbon dioxide fracturing in different formation conditions. | SONG Weiqiang NI Hongjian TANG Peng ZHANG Shichuan GAO Jichao ZHANGJunming SHEN Baotang | 2021 | Journal of Thermal Science2021，30，4： | 0 |
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