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| 1 | Instability mechanism and control technology of soft rock roadway affected by mining and high confined water显示文摘Based on deformation and failure characteristics of the second belt conveyor roadway at level II of Zhuxianzhuang coal mine, laboratory experiments, numerical calculation and field test were adopted to analyze the composition and microstructure of mudstone, the law of mudstone hydration and its strength weakening induced by water, the characteristics of surrounding rock deformation and failure under the action of confined water. Results showed that montmorillonite clay minerals accounted for as much as 76% of mudstone, with a large number of pores existing in the microstructure. Besides, as the molecular structure of montmorillonite changed, mudstone microstructure damage occurred with the macroscopic manifestation of its rheological instability. Weakening degree of confined water on residual strength of mudstone was almost 50%. The instability mechanism of soft rock roadway caused by high confined water is that surrounding rock circulates the process of ‘‘fracture-seepage-mud ding-closed'' twice, which weakens its strength and leads to roadway instability. A combined support technology, namely the, ‘‘high-toughness sealing layer + hollow grouting cables + full-length anchoring bolts with deep borehole'' was proposed. Based on field observation, the soft rock roadway was controlled effectively, which also verified the effectiveness of new control technology for surrounding rock. | Li Guichen Jiang Zuohan Lv Chuangxin Huang Chao Chen Gui Li Mingyuan | 2015 | International Journal of Mining Science and Technology2015，25，4： | 11 |
| 2 | Creep characteristics of coal and rock investigated by nanoindentation显示文摘In coal mining industry,with the depth growing of coal mines,the creep behaviours of coal and rock can extensively affect the mining safety,coalbed methane recovery and geo-sequestration.To acquire a better insight into their creep characteristics,an efficient and robust researching technique,nanoindentation,was applied to investigate the creep performances of coal and rock samples obtained from two coal mines in the east of China.Creep characteristics were reflected by evaluating the curves of creep depth versus creep time of nanoindentation tests during the load-holding period at the peak load of 30 mN.These curves can be divided into two stages:transient stage and steady stage;and the time of load-holding period of 5 s,which is the dividing point between two stages,can efficiently avoid the influence of creep displacement on the unloading curves.The exponential function can perfectly fit creep curves and Kelvin model can be used to calculate the rheological parameters of coal and rock samples.Calculated results yield values for the creep modulus and viscosity terms of coal and rock.This study also settled a particular emphasis on the selection of the positions of indentations to obtain the rheological properties of mineralogical constituents in heterogonous coal and rock samples and their elastic aftereffect. | Changlun Sun Guichen Li Mohamed Elgharib Gomah Jiahui Xu Yuantian Sun | 2020 | International Journal of Mining Science and Technology2020，30，6： | 8 |
| 3 | Development of ensemble learning models to evaluate the strength of coal-grout materials显示文摘In the loose and fractured coal seam with particularly low uniaxial compressive strength(UCS),driving a roadway is extremely difficult as roof falling and wall spalling occur frequently.To address this issue,the jet grouting(JG)technique(high-pressure grout mixed with coal particles)was first introduced in this study to improve the self-supporting ability of coal mass.To evaluate the strength of the jet-grouted coal-grout composite(JG composite),the UCS evolution patterns were analyzed by preparing 405 specimens combining the influential variables of grout types,curing time,and coal to grout(C/G)ratio.Furthermore,the relationships between UCS and these influencing variables were modeled using ensemble learning methods i.e.gradient boosted regression tree(GBRT)and random forest(RF)with their hyperparameters tuned by the particle swarm optimization(PSO).The results showed that the chemical grout composite has higher short-term strength,while the cement grout composite can achieve more stable strength in the long term.The PSO-GBRT and PSO-RF models can both achieve high prediction accuracy.Also,the variable importance analysis demonstrated that the grout type and curing time should be considered carefully.This study provides a robust intelligent model for predicting UCS of JG composites,which boosts JG design in the field. | Yuantian Sun Guichen Li Nong Zhang Qingliang Chang Jiahui Xu Junfei Zhang | 2021 | International Journal of Mining Science and Technology2021，31，2： | 6 |
| 4 | On the γ' precipitates of the normal and inverse Portevin-Le Chatelier effect in a wrought Ni-base superalloy显示文摘The Portevin-Le Chatelier(PLC) effects in a wrought Ni-base superalloy with different γ' precipitates contents have been investigated. Detailed analysis on the serration type of the tensile curves indicates that the γ' precipitates have a decisive influence on the transformation from normal to inverse PLC behavior, which is rarely proposed in other works. It is considered that the γ' precipitates play the same role in PLC effect as temperature and strain rate for the investigated wrought Ni-base superalloy. | Xinguang Wang Guoming Han Chuanyong Cui Shuai Guan Jinguo Li Guichen Hou Yizhou Zhou Xiaofeng Sun | 2019 | Journal of Materials Science & Technology2019，35，1： | 3 |
| 5 | Experimental investigation on the nanoindentation viscoelastic constitutive model of quartz and kaolinite in mudstone显示文摘The creep behaviors in deep underground engineering structures,especially in soft rocks,have a remarkable impact on the long-term stability of the excavations,which finally leads to the high risk and failure of it.Accordingly,it is essential to recognize the time-dependent deformation through the investigation of this phenomenon.In this study,the creep behaviors of soft rocks were examined to help understand the underlying mechanism of the extended time-dependent deformation.Due to the limited results about the time-dependent properties of the constituents of the rock that reveal their heterogeneity,the targeting nanoindentation technique(TNIT),was adopted to investigate the viscoelastic characteristics of kaolinite and quartz in a two-constituent mudstone sample.The TNIT consists of identifications of mineralogical ingredients in mudstone and nanoindentation experiments on each identified constituent.After conducting experiments,the unloading stages of the typical indentation curves were analyzed to calculate the hardness and elastic modulus of both elements in mudstone.Additionally,the 180 s load-holding stages with the peak load of 50 mN were transformed into the typical creep strain-time curves for fitting analysis by using the Kelvin model,the standard viscoelastic model,and the extended viscoelastic model.Fitting results show that the standard viscoelastic model not only can perfectly express the nanoindentation creep behaviors of both kaolinite and quartz but also can produce suitable constants used to measure their creep parameters.The creep parameters of kaolinite are much smaller than that of quartz,which causes the considerable time-dependent deformation of the soft mudstone.Eventually,the standard viscoelastic model was also verified on the quartz in a sandstone sample. | Changlun Sun Guichen Li Mohamed Elgharib Gomah Jiahui Xu Haoyu Rong | 2021 | International Journal of Coal Science & Technology2021，8，5： | 2 |
| 6 | Analysis on mechanism and key factors of surrounding rock instability in deeply inclined roadway affected by argillation and water seepage显示文摘Based on the characteristics of surrounding rocks for deeply inclined roadway affected by argillation and water seepage, a structure model of layer crack plate was established to analyze the shear sliding instability mechanism. Through solid mechanics analysis of anchored surrounding rock with defect from water seepage, combined with numerical analysis for instability mechanism under water seepage in deeply inclined roadway, key factors were proposed. Results show that with increasing height of layer crack plate, lateral buckling critical load value for high wall of the roadway decreases; there is a multistage distribution for tensile stress along the anchor bolt with defect under pulling state condition;groundwater seepage seriously affects the strength of surrounding rock of the roadway, to some extent the plastic zone of the high side rises up to 8 m. Finally some support strategies were proposed for the inclined roadway and successfully applied to Haoyuan coal mine in Tiela mining area,western China. | Ma Rui Li Guichen Zhang Nong Liu Cong Wei Yinghao Zhang Ming | 2015 | International Journal of Mining Science and Technology2015，25，3： | 2 |
| 7 | Machine learning-based constitutive models for cement-grouted coal specimens under shearing显示文摘Cement-based grouting has been widely used in mining engineering;its constitutive law has not been comprehensively studied.In this study,a novel constitutive law of cement-grouted coal specimens(CGCS)was developed using hybrid machine learning(ML)algorithms.Shear tests were performed on CGCS for the analysis of stress-strain curves and the preparation of the dataset.To maintain the interpretation of the trained ML models,regression tree(RT)was used as the main technique.The effect of maximum RT depth(Maxdepth)on its performance was studied,and the hyperparameters of RT were tuned using the genetic algorithm(GA).The RT performance was also compared with ensemble learning techniques.The optimum correlation coefficient on the training set was determined as 0.835,0.946,0.981,and 0.985 for RT models with Maxdepth=3,5,7,and 9,respectively.The overall correlation coefficient was over 0.9 when the Maxdepth≥5,indicating that the constitutive law of CGCS can be well described.However,the failure type of CGCS could not be captured using the trained RT models.Random forest was found to be the optimum algorithm for the constitutive modeling of CGCS,while RT with the Maxdepth=3 performed the worst. | Guichen Li Yuantian Sun Chongchong Qi | 2021 | International Journal of Mining Science and Technology2021，31，5： | 1 |
| 8 | De-stressed mining of multi-seams:Surrounding rock control during the mining of a roadway in the overlying protected seam显示文摘在 overlying 的包围岩石控制保护的煤缝接是为缝接得多的煤的强调 de 的采矿的一个挑战性的话题。车道控制上的当前的研究调查结果在有变化厚度的一个复杂粗糙的房顶的一个物理模型的设计被使用。模型被用来学习动态压力引起的车道不稳定性和倒塌。结果证明当房顶的厚度超过固定深度时,车道安全是最少的,房顶为倒塌有最大的可能性。数字模拟也被执行在内在的保护的缝接采矿期间在车道挖掘前后学习压力再分配。车道排水量和骨折的进化由支持方法影响了很好被学习了。为采矿的一系列支持原则和技术影响了车道在 Huainan 矿在成功的实际申请的示范以后被建议了。这些原则和技术具有到在中国的深煤采矿支持的扩大价值。 | Wang Cheng Zhang Nong Li Guichen Zhang Nianchao | 2011 | Mining Science and Technology2011，21，2： | 1 |
| 9 | Determination of long-chain fatty acids in bryophyte plants extracts by HPLC with fluorescence detection and identification with MS显示文摘 | Jinmao You Xianen Zhao Yourui Suo Yulin Li Honglun Wang Guichen Chen | 2007 | Journal of Chromatography B2007，848，： | 1 |
| 10 | Evolution of TCP Phase During Long Term Thermal Exposure in Several Re-Containing Single Crystal Superalloys显示文摘The application and component designs of single crystal superalloys are restricted by the precipitation of topologically closed packed(TCP)phases,which can deteriorate the microstructural stability of the alloys severely.Limited researches concerning the type and morphology evolution of TCP phases under elevated temperature conditions have been reported previously.In the present work,three Re-containing single crystal alloys were designed to investigate TCP phase evolution via long term isothermal exposure tests at 1120℃while the effects of Re on the microstructural characteristic and elements segregation were also clarified.The results showed that the addition of Re increased the instability of the alloys and the volume fraction of the TCP phases exceeded 5 vol%when the Re content reached 3 wt%.The increasing Re content had also raised the precipitation temperature of TCP phases but it did not change the type of them after long term aging;all the TCP particles were identified asμphase in this study.Moreover,the elements segregation became considerably serious as Re addition increased constantly,which brought about various morphologies of theμphase in the experimental alloys.In particular,the rod-like and needle-likeμphases demonstrated the typical orientation withinγmatrix while the blockyμphase was dispersedly distributed in the space.No specific orientation relationship could be observed in theμphase when the addition of Re exceeded certain threshold value. | Zihao Tan Lin Yang Xinguang Wang Yunling Du Lihua Ye Guichen Hou Yanhong Yang Jinlai Liu Jide Liu Jinguo Li Yizhou Zhou Xiaofeng Sun | 2020 | Acta Metallurgica Sinica(English Letters)2020，33，5： | 1 |
| 11 | Unprecedented differences in the diamond nucleation density between carbon-and silicon-faces of 4H-silicon carbides显示文摘4H-silicon carbides deposited by diamond films have wide applications in many fields such as semiconductor heterojunction,heat sink and mechanical sealing.Nucleation plays a critical role in the deposition of the diamond film on 4H-silicon carbides.Nevertheless,as a typical polar material,the fundamental mechanism of diamond nucleation on different faces of 4H-silicon carbides has not been fully understood yet.In this contribution,nucleation of diamond was performed on the carbon-and silicon-faces of 4H-silicon carbides in a direct current chemical vapor deposition device.The nucleation density on the carbon-face is higher by 2-3 orders of magnitude compared to the silicon-face.Transmission electron microscopy verifies that there are high density diamond nuclei on the interface between the carbon-face and the diamond film,which is different from columnar diamond growth structure on the silicon-face.Transition state theory calculation reveals that the unprecedented distinction of the nucleation density between the carbon-face and the silicon-face is attributed to different desorption rates of the absorbed hydrocarbon radicals.In addition,kinetic model simulations demonstrate that it is more difficult to form CH2(s)-CH2(s)dimers on silicon-faces than carbon-faces,resulting in much lower nucleation densities on silicon-faces. | Bo Wang Pitsiri Sukkaew Guichen Song Andreas Rosenkranz Yunxiang Lu Kazhihito Nishimura Jia Wang Jilei Lyu Yang Cao Jian Yi Lars Ojamae He Li Nanjiang | 2020 | Chinese Chemical Letters2020，31，7： | 0 |
| 12 | Synergistic effects of PtFe/CeO_(2)catalysts afford high catalytic performance in selective hydrogenation of cinnamaldehyde显示文摘Selective hydrogenation of unsaturated aldehydes remains a grand challenge in controlling chemoselectivity up to now.We synthesized a series of PtFex/CeO_(2)catalysts,which were characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)as well as temperature-programmed-reduction by hydrogen(H2-TPR).The catalytic performance of PtFex/CeO_(2),including cinnamaldehyde(CAL)conversion and selectivity toward cinnamyl alcohol(COL),is improved remarkably by introduction of Fe species in the Pt particles in the selective CAL hydrogenation under mild conditions.XPS results indicate that the electron transfer from Fe to Pt promotes CAL adsorption,resulting in the enhanced CAL conversion.And the COL selectivity is improved by CAL adsorption via an interaction of C=O group with surface oxygen defect sites because of interaction between PtFe and CeO_(2)support.In all,this study may provide some hints to design efficient nano Pt particles for the selective hydrogenation. | Xia Gong Quanquan Shi Xinyu Zhang Jinmei Li Guichen Ping Hui Xu Hongjing Ding Gao Li | 2023 | Journal of Rare Earths2023，41，2： | 0 |
| 13 | Numerical modeling on strain energy evolution in rock system interaction with energy-absorbing prop and rock bolt显示文摘The interaction mechanism between coal and rock masses with supporting materials is significant in roadway control, especially in deep underground mining situations where dynamic hazards frequently happened due to high geo-stress and strong disturbed effects. This paper is to investigate the strain energy evolution in the interaction between coal and rock masses with self-designed energy-absorbing props and rock bolts by numerical modeling with the finite difference method. The interaction between rock and rock bolt/prop is accomplished by the cables element and the interface between the inner and outer props. Roadway excavation and coal extraction conditions in deep mining are numerically employed to investigate deformation, plastic zone ranges, strain energy input, accumulation, dissipation,and release. The effect on strain energy input, accumulation, dissipation, and release with rock deformation, and the plastic zone is addressed. A ratio of strain energy accumulation, dissipation, and release with energy input a, β, γ is to assess the dynamic hazards. The effects on roadway excavation and coal extraction steps of a, β, γ are discussed. The results show that:(1) In deep high geo-stress roadways, the energyabsorbing support system plays a dual role in resisting deformation and reducing the scope of plastic zones in surrounding rock, as well as absorbing energy release in the surrounding rock, especially in the coal extraction state to mitigate disturbed effects.(2) The strain energy input, accumulation is dependent on roadway deformation, the strain energy dissipation is relied on plastic zone area and disturbed effects, and strain energy release density is the difference among the three. The function of energyabsorbing rock bolts and props play a key role to mitigate strain energy release density and amount, especially in coal extraction condition, with a peak density value from 4×10^(4) to 1×10^(4)J/m^(3), and amount value from 3.57×10^(8) to 1.90×10^(6)J.(3) When mining is advanced in small steps, the strain energy accumulation is dominated. While in a large step, the released energy is dominant, thus a more dynamic hazards proneness. The energy-absorbing rock bolt and prop can reduce three times strain energy release amount, thus reducing the dynamic hazards. The results suggest that energy-absorbing props and rock bolts can effectively reduce the strain energy in the coal and rock masses, and prevent rock bursts and other hazards.The numerical model developed in this study can also be used to optimize the design of energyabsorbing props and rock bolts for specific mining conditions. | Yang Hao Chunhui Liu Yu Wu Hai Pu Yanlong Chen Lingling Shen Guichen Li | 2023 | International Journal of Mining Science and Technology2023，33，10： | 0 |
| 14 | Numerical study on the heat transfer performance of coaxial shallow borehole heat exchanger显示文摘In the present work,a numerical investigation on the coaxial shallow borehole heat exchanger based on Com-putational Fluid Dynamics(CFD)technique in Hefei city of China has been performed.The effects of design parameters,including inlet flow rate,inlet fluid temperature,inner pipe material and outer pipe diameter,on the heat transfer performance were systematically studied.Besides,the thermal behavior along the pipe has been carefully examined with focus on the thermal short-circuiting phenomena.When the fluid inlet velocity is less than the critical value,the turbulence intensity increases and the Nusselt number increases with the inlet flow rate increasing.However,there is sufficient time for heat transfer between the fluid in inner pipe and outer pipe because of low flow rates,leading to large heat loss,i.e.,thermal short-circuiting phenomenon.It is found that with the inlet flow rate increasing,the heat transfer increases first and then decreases,and the rate of reduction slows down gradually.When the inlet flow rate increases,the pumping power undergoes exponential growth.As the inlet temperature increasing,the heat transfer decreases almost linearly.Moreover,when the soil temperature at the top of the casing is lower than that of the fluid in the casing,heat is transferred from the fluid in the casing to the soil,and the heat loss increases with the increase of the inlet fluid temperature.The material of inner pipe with high heat conductivity would result in large heat loss under the influence of thermal short-circuiting.The heat load increases while the pumping power required decreases with the increasing of outer pipe diameter.This study is very beneficial for the coaxial shallow borehole exchanger designs and energy conservation of buildings. | Guichen Li Jianzhi Yang Xiaowei Zhu Zhihe Shen | 2021 | Energy and Built Environment2021，2，4： | 0 |
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