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Time-dependent squeezing deformation mechanism of tunnels in layered soft-rock stratum under high geo-stress

Journal of Mountain Science 2021年第5期18卷 1371-1390页

作者： CHEN Zi-quan HE Chuan WANG Jun ma chun-chi Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China Sichuan Highway Planning Survey Design and Research Institute Ltd Chengdu 610041China Key Laboratory of Engineering Structures of Heavy Haul Railway Ministry of EducationCentral South UniversityChangsha 410075China

Large squeezing deformation of layered soft rock tunnel under high geo-stress has a significant time-dependent deformation *** this paper,we studied the deformation mechanism during the construction period of deep-buried softrock tunnel by means of a combination of field observations and a numerical ***,a new classification criterion for large deformations based on the power exponent variation law between the deformation and the strength-stress ratio is ***,the initial damage tensor reflecting the bedding plane(joint)distribution and an equivalent damage evolution equation derived from the viscoplastic strain are introduced based on the geometric research method,i.e.,a new rheological damage model(RDL model)of layered soft rock is established consisting of elastic,viscous,viscoelastic,viscoplastic and plastic elements.A field test was conducted on the maoxian tunnel in Sichuan province,southwestern china,which is in broken phyllite(layered soft rock)under high *** tunnel has experienced large deformation due to serious squeezing pressure,thus we adopted double primary support method to overcome the supporting structure failure *** rheological parameters of phyllite in the maoxian tunnel were recognized by using SA-PSO optimization,and the RDL model does a good job in describing the time-dependent deformation behavior of a layered soft-rock tunnel under high ***,the RDL model was used to investigate the supporting effect and bearing mechanism of the double primary support *** with the single primary support method,the surrounding rock pressure,secondary lining force,surrounding rock deformation,and the depth of the damage to the rock mass was reduced by 40%-60%after the double primary support method was used.

关键词： Deformation mechanism Layered soft rock tunnel High geostress Large squeezing deformation Rheological damage model

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Effect of stress paths on failure mechanism and progressive damage of hard-brittle rock

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Journal of Mountain Science 2021年第9期18卷 2486-2502页

作者： CHEN Zi-quan HE Chuan HU Xiong-yu ma chun-chi Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China Key Laboratory of Engineering Structures of Heavy Haul Railway Ministry of EducationCentral South UniversityChangsha 410075China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China

During deep buried hard-brittle rock tunnel excavation,the surrounding rock experiences a complicated stress path and stress adjustment *** the adjusted stress exceeds the ultimate bearing capacity of rockmass,a rock failure mode defined as stress-cracking type will *** order to investigate the effect of stress paths on failure mechanism and progressive damage of deep-buried rockmass,the cyclic loading-unloading,loading-unloading,uniaxial,conventional and unloading triaxial compression tests on samples of hard-brittle sandstone were *** to the experimental results,increase in the confining pressure was beneficial to improve the mechanical parameters of rock,but it will reduce the brittle failure *** with conventional triaxial compression,the sandstone under unloading state had more remarkable stress drop and unstable failure ***,it was found that the energy dissipation and energy release in the whole process of rock deformation were the internal power of driven rock progressive *** the increase of confining pressure,the energy hardening and energy accumulation features of rock were weakened,while the progressive damage evolution characteristics could be *** unloading state,more energy could be converted into elastic energy in the energy softening phase(σeb-σP),so that the prepeak damage rate of rock was lower than that of conventional triaxial compression ***,the energy dissipation rate of rock after peak strength decreased linearly with the increase of confining pressure under conventional triaxial compression state,while in unloading state it showed the opposite law.

关键词： Hard-brittle rock Stress path Confining pressure Failure mechanism Progressive damage

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Seepage field distribution and water inflow laws of tunnels in water-rich regions

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Journal of Mountain Science 2022年第2期19卷 591-605页

作者： LI Zheng CHEN Zi-quan HE Chuan ma chun-chi DUAN Chao-ran School of Civil Engineering Chongqing UniversityChongqing 400045China Key Laboratory of Transportation Tunnel Engineering Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China Chongqing University Industrial Technology Research Institute Chongqing 401329China Chongqing City Construction Investment(Group)Co. LtdChongqing 400023China State Key Laboratory of Geohazard Prevention and Geoenvironment Protection Chengdu University of TechnologyChengdu 610059China School of Civil Engineering Changzhou Institute of TechnologyChangzhou 213032China

Currently,the water inrush hazards during tunnel construction,the water leakage during tunnel operation,and the accompanying disturbances to the ecological environment have become the main problems that affect the structural safety of tunnels in water-rich *** this paper,a tunnel seepage model testing system was used to conduct experiments of the grouting circle and primary support with different permeability *** influences of the supporting structures on the water inflow laws and the distribution of the water pressure in the tunnel were *** the decrease in the permeability coefficient of the grouting circle or the primary support,the inflow rate of water into the tunnel showed a non-linear decreasing *** comparison,the water inflow reduction effect of grouting circle was much better than that of primary *** the increase of the permeability coefficient of the grouting ring,the water pressure behind the primary lining increases gradually,while the water pressure behind the grouting ring ***,the grouting of surrounding rock during the construction of water-rich tunnel can effectively weaken the hydraulic connection,reduce the influence range of seepage,and significantly reduce the decline of ***,the seepage tests at different hydrostatic heads and hydrodynamic heads during tunnel operation period were also *** the hydrostatic head decreased,the water pressure at each characteristic point decreased approximately linearly,and the water inflow rate also had a gradual downward *** the action of hydrodynamic head,the water pressure had an obvious lagging effect,which was not conducive to the stability of the supporting structures,and it could be mitigated by actively regulating the drainage *** with the hydrostatic head,the hydrodynamic head could change the real-time rate of water inflow to the tunnel and broke the dynamic balance between the water pressure and water inflow

关键词： Water-rich tunnel Seepage field distribution Water inflow law Construction period Operation period

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Identifying crack initiation stress threshold in brittle rocks using axial strain stiffness characteristics

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Journal of Mountain Science 2018年第6期15卷 1371-1382页

作者： GAO Mei-ben LI Tian-bin MENG Lu-bo ma chun-chi XING Hui-lin state key laboratory of geohazard prevention and geoenvironment protection chengdu university of technologyChengdu 610059China college of environment and civil engineering chengdu university of technologyChengdu 610059China centre for geoscience computing school of earth sciencesthe university of queenslandSt Lucia.QLD 4072Australia

As an estimate for the in-situ spalling strength around massive underground excavations to moderately jointed brittle rocks, crack initiation stress marks the initiation of rock micro fracturing. It is crucial to accurately identify crack initiation stress level by proper method. In this study, confined compression tests of sandstone samples are used to examine the validity/applicability of proposed axial strain stiffness method. The results show that by highlighting the minuscule changes in stress-strain curve, the axial strain stiffness curve provided further insight into rock failure process and revealed five stages:(a) irregular fluctuation,(b) nearly horizontal regular fluctuation,(c) irregular fluctuation gradually decreasing to zero,(d) extreme fluctuation, and(e) near zero, which mainly correspond to five stages of stress–strain curve. The ratio of crack-initiation stress to peak strength determined using this approach is 0.44–0.51, similar to the ranges previously reported by other researchers. In this method, the key is to accurately detect the end point of the stage(b), "nearly horizontal regular fluctuation" characterized by a sudden change in axial strain stiffness curve, and the sudden change signifies crack initiation in rock sample. Finally, the research indicates that the axial strain stiffness curve can provide a mean to identify the crack-initiation stress thresholds in brittle rocks.

关键词： Brittle rock fracture Rock failure Sandstone Crack initiation stress Axial strain-stiffness Triaxial test

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乡村振兴战略与国家治理能力现代化的耦合机理

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江苏行政学院学报 2018年第6期 63-70页

作者：马华马池春山西大学城乡发展研究院太原030000

改革开放以来,中国的国家治理实践与国家治理能力现代化之间存在高度耦合,乡村振兴战略同国家治理能力现代化之间同样存在强耦合性。一方面,乡村振兴战略的实施过程包含了一定的国家治理能力需求,包括顶层设计与制度供给能力、资源配置... 详细信息

改革开放以来,中国的国家治理实践与国家治理能力现代化之间存在高度耦合,乡村振兴战略同国家治理能力现代化之间同样存在强耦合性。一方面,乡村振兴战略的实施过程包含了一定的国家治理能力需求,包括顶层设计与制度供给能力、资源配置能力、乡村治理体系建构能力等,当实践过程出现治理能力需求同治理能力供给低匹配困境时,这种需求便转化为国家治理能力现代化的直接动力,进而推动国家在制度建设与制度执行、全面深化改革、综合发展与协调发展、国家与乡村社会关系协调等方面的治理能力变革。另一方面,国家治理能力的现代化建设则为乡村振兴战略顺利实施提供了治理能力保障,具体体现在激发主体活力、提升发展的有序性、增强资源配置效率、减少政策执行阻滞。

关键词：乡村振兴战略国家治理能力国家治理现代化

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中国乡村治理四十年变迁与经验

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理论与改革 2018年第6期 21-29页

作者：马池春马华山西大学政治与公共管理学院山西大学中国城乡发展研究院

回顾四十年来中国乡村治理实践的演进历程,可以将其分为以下几个时期:乡村治理自我探索时期、乡村治理制度化建设时期、乡村治理组织化建设时期、农民主体能力建设时期以及新时代乡村治理国家整合时期。进一步研究发现,中国乡村治理四... 详细信息

回顾四十年来中国乡村治理实践的演进历程,可以将其分为以下几个时期:乡村治理自我探索时期、乡村治理制度化建设时期、乡村治理组织化建设时期、农民主体能力建设时期以及新时代乡村治理国家整合时期。进一步研究发现,中国乡村治理四十年变迁蕴含着鲜明的中国经验:(1)中国政治体制优势下的国家高位推动;(2)改革进程中始终坚持农民主体地位,尊重农民群众首创精神;(3)遵循试点到整体的渐进性改革路线,构建了改革、发展与稳定三角平衡格局。中国乡村治理四十年实践所蕴含的宝贵经验对推进新时代乡村治理改革创新具有重要启示和意义。

关键词：乡村治理四十年变迁经验

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基于EMS微震参数的岩爆预警方法及探讨

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岩土力学 2018年第2期39卷 765-774页

作者：马春驰李天斌张航王剑锋成都理工大学环境与土木工程学院四川成都610059 成都理工大学地质灾害防治与地质环境保护国家重点实验室四川成都610059

一系列深埋长大隧道工程在我国西部涌现,深埋隧道围岩的岩爆成因机制及监测预警成为亟待解决的课题。微震监测作为岩体微破裂空间监测技术在隧道工程岩爆预警上发挥了重要作用。由于微震数据存在的波动性(时间序列)、离散性(空间分布)... 详细信息

一系列深埋长大隧道工程在我国西部涌现,深埋隧道围岩的岩爆成因机制及监测预警成为亟待解决的课题。微震监测作为岩体微破裂空间监测技术在隧道工程岩爆预警上发挥了重要作用。由于微震数据存在的波动性(时间序列)、离散性(空间分布)和误差,利用震源参数随施工循环的演化特征评估岩爆发育过程并非足够稳定、有效。基于3种微震监测易于获取且紧密联系的震源参数(地震能量、地震矩和视应力),扩展建立了用于岩爆评估与预警的EMS方法。该方法定义了地震能量、地震矩、视应力3种评价指标,并获得了3种评价指标间的关系;将3种评价指标用于岩爆预测,并进行了岩爆等级评估;同时还给出了微震路径与震源参数空间的概念。最后,将EMS方法应用于巴陕高速米仓山隧道的岩爆灾害实例,对岩爆里程段微震事件簇(微震事件聚集区域)内岩体累进破裂和岩爆发育过程进行了评估,实现了简易有效的微震数据日常处理与岩爆灾害评估预警。

关键词：岩石力学微震监测震源参数岩爆评估岩爆预警

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Small extracellular vesicles derived from human induced pluripotent stem cell-differentiated neural progenitor cells mitigate retinal ganglion cell degeneration in a mouse model of optic nerve injury

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Neural Regeneration Research 2025年第2期20卷 587-597页

作者： Tong Li Hui-Min Xing Hai-Dong Qian Qiao Gao Sheng-Lan Xu Hua ma Zai-Long chi State Key Laboratory of Ophthalmology Optometry and Visual ScienceEye HospitalWenzhou Medical UniversityWenzhouZhejiang ProvinceChina National Clinical Research Center for Ocular Diseases Eye HospitalWenzhou Medical UniversityWenzhouZhejiang ProvinceChina

Several studies have found that transplantation of neural progenitor cells(NPCs)promotes the survival of injured ***,a poor integration rate and high risk of tumorigenicity after cell transplantation limits their clinical *** extracellular vesicles(sEVs)contain bioactive molecules for neuronal protection and *** studies have shown that stem/progenitor cell-derived sEVs can promote neuronal survival and recovery of neurological function in neurodegenerative eye diseases and other eye *** this study,we intravitreally transplanted sEVs derived from human induced pluripotent stem cells(hiPSCs)and hiPSCs-differentiated NPCs(hiPSC-NPC)in a mouse model of optic nerve *** results show that these intravitreally injected sEVs were ingested by retinal cells,especially those localized in the ganglion cell *** with hiPSC-NPC-derived sEVs mitigated optic nerve crush-induced retinal ganglion cell degeneration,and regulated the retinal microenvironment by inhibiting excessive activation of *** analysis further revealed that hiPSC-NPC derived sEVs transported neuroprotective and anti-inflammatory miRNA cargos to target cells,which had protective effects on RGCs after optic nerve *** findings suggest that sEVs derived from hiPSC-NPC are a promising cell-free therapeutic strategy for optic neuropathy.

关键词： exosome miRNA neural progenitor cell neurodegeneration neuroinflammation neuroprotection optic nerve crush optic neuropathy retinal ganglion cell small extracellular vesicles

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不同应力路径下砂岩能耗变化规律试验研究

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工程力学 2016年第6期33卷 120-128页

作者：陈子全李天斌陈国庆马春驰成都理工大学地质灾害防治与地质环境保护国家重点实验室成都610059

为研究不同应力路径下岩石的能耗变化规律,采用MTS815岩石力学试验系统开展了砂岩的单轴压缩、常规三轴和卸荷三轴试验。结果表明:耗散能曲线变化是岩石内部损伤和破裂产生的表现,在弹塑性变形阶段,常规三轴耗散的能量占岩石吸收总能量... 详细信息

为研究不同应力路径下岩石的能耗变化规律,采用MTS815岩石力学试验系统开展了砂岩的单轴压缩、常规三轴和卸荷三轴试验。结果表明:耗散能曲线变化是岩石内部损伤和破裂产生的表现,在弹塑性变形阶段,常规三轴耗散的能量占岩石吸收总能量的比例最大,卸荷三轴次之,单轴压缩最小;岩石的储能极限与围压具有明显的线性关系,单轴压缩试验中岩石的储能极限最低,卸荷三轴次之,常规三轴试验岩石的储能极限最高;岩石峰前和峰后的能量耗散速率与围压也具有良好的线性关系,峰后应力跌落阶段能量耗散速率明显较峰前能量耗散速率大数倍至数十倍,说明岩石峰前损伤速率较小,而峰后却快速损伤破裂,耗散能曲线的突然变陡表明岩石破坏发生。

关键词：应力路径总能量弹性应变能耗散能能量释放

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Hydration, Microstructure, and Properties of Sulphoaluminate Cement in Pure Water and Simulated Seawater

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Journal of Wuhan University of Technology(materials Science) 2025年第1期40卷 187-193页

作者： ma Jie china Railway Design Corporation Tianjin 300250China

Paste and mortar specimens were prepared with sulfoaluminate cement(SAC),P⋅O 42.5 ordinary Portland cement(OPC),and standard sand,and mixed and cured with pure water and artificial seawater,*** mechanical properties of mortar specimens were *** and microstructure of paste specimens were also investigated using X-ray diffraction(XRD),scanning electron microscope(SEM),and 27Al nuclear magnetic resonance(NMR),*** results indicate that SAC mortar samples mixed and cured by seawater have faster strength growth before 28 d and higher compressive strength than OPC mortar *** to curing in deionized water,the hydration products of SAC are somewhat coarser when cured in simulated *** evolution of aluminum phase hydration products during the hydration process of SAC mixed and cured in simulated seawater is quite different from that of *** 3 to 28 d,the content of each aluminum phase hydration product in SAC paste cured in simulated seawater changed little,while that in OPC paste changed significantly;for example,from 7 to 28 d,the content of ettringite(AFt)in OPC paste increased *** type of AFt formed loosely,harming the mortar's microstructure.

关键词： sulfoaluminate cement seawater mixing and curing 27Al NMR AFt

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