Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stre...Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.展开更多
目的:观察化瘀通络灸对血管性痴呆大鼠Ras同源物基因组成员A(Ras homolog gene family member A,RhoA)/Rho激酶(Rho associated protein kinase, ROCK)轴突生长抑制性信号通路相关蛋白的影响,探讨其治疗血管性痴呆的机制。方法:使用Mor...目的:观察化瘀通络灸对血管性痴呆大鼠Ras同源物基因组成员A(Ras homolog gene family member A,RhoA)/Rho激酶(Rho associated protein kinase, ROCK)轴突生长抑制性信号通路相关蛋白的影响,探讨其治疗血管性痴呆的机制。方法:使用Morris水迷宫筛除贴壁、原地旋转或溺水的Wistar大鼠,将符合条件大鼠分为假手术组、造模组。假手术组暴露大鼠颈总动脉;造模组用改良的双侧颈总动脉永久结扎术制备血管性痴呆大鼠模型,术后3 d用水迷宫对大鼠进行模型鉴定,将合格者随机分为模型组、艾灸组和西药组。于鉴定次日对大鼠进行治疗,艾灸组悬灸百会、大椎、神庭,20 min/次,1次/d, 1周为1疗程,2个疗程间休息1 d,共3个疗程;西药组用吡拉西坦溶液灌胃,2次/d;假手术组、模型组行灸架固定。治疗结束,取大鼠脑组织,用免疫荧光单染法、蛋白免疫印迹法检测其脑内目的蛋白RhoA、Rho相关螺旋卷曲蛋白激酶Ⅱ(Rho protein-related curl spiral kinase-Ⅱ,ROCKⅡ)、肌球蛋白轻链磷酸化(Phosphorylation of myosin light chain, P-MLC)的阳性表达。结果:模型组大鼠海马、皮质RhoA、ROCKⅡ、P-MLC蛋白表达高于假手术组(P<0.01);艾灸组、西药组海马和皮质RhoA、ROCKⅡ、P-MLC蛋白表达较模型组低(P<0.05);艾灸组皮质ROCKⅡ蛋白表达较西药组稍低(P<0.05);艾灸组与西药组海马ROCKⅡ、海马与皮质RhoA、P-MLC蛋白表达差异无统计学意义(P>0.05)。结论:化瘀通络灸可能是通过下调RhoA/ROCK轴突生长抑制性信号通路相关蛋白的表达提高血管性痴呆大鼠的记忆力,从而发挥治疗血管性痴呆的作用。展开更多
The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress.Under such sof...The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress.Under such soft rock geological conditions,the large deformation of the surrounding rock can easily lead to the failure of supporting structures,including shotcrete cracks,spalling,and steel arch distortion.To improve the lining support performance during the large deformation of squeezed surrounding rock,this work selects aluminum foam with densities of 0.25 g/cm3,0.42 g/cm3 and 0.61 g/cm3 as the buffer layer material and carries out uniaxial confined compression tests.Through the evaluation and analysis of energy absorption and the comparison of the yield pressure of aluminum foam with those of other cushioning materials and yield pressure support systems,the strength,deformation and energy absorption of aluminum foam with a density of 0.25 g/cm3 meet the yield pressure performance requirements.The numerical model of the buffer layer yielding support system is then established via the finite element analysis software ABAQUS,and the influence of the buffer layer setting on the lining support is analyzed.Compared with the conventional support scheme,the addition of an aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining.The maximum and minimum principal stresses of the primary support are reduced by 13%and 15%,respectively.The maximum and minimum principal stresses of the secondary lining are reduced by 15%and 12%,respectively,and the displacement deformation of the secondary lining position is reduced by 15%.In summary,the application of aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining,improve the stress safety of the support and reduce the deformation of the support.展开更多
In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of st...In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of strip footing placed on the rock mass.By taking into account the various boundary constraints across the surface of crack edges,the study investigates the presence of two categories of surface cracks,namely(1)separated crack,and(2)fine crack.The lower bound limit analysis is employed in conjunction with the finite element method(LBFELA)to conduct the numerical analysis.In order to evaluate rock mass yielding,the power conic programming(PCP)method is utilized to implement the generalized Hoek-Brown(GHB)failure criterion.The stability of the strip footing is analyzed by determining the bearing capacity factor(Nσγ),which is presented in the form of design charts by varying the strength parameters of rock,including the Geological Strength Index(GSI),Hoek-Brown material parameter(mi),Disturbance factor(D),and Normalised Uniaxial Compressive Strength(σci/γB),whereγis the unit weight of rock mass,and B is the width of strip footing.The study also investigates the impact of cracks on strip footings,considering different positions of the crack(LC)and depths of the crack(DC).The results demonstrate that the influence of the fine crack is only noticeable until the LC/B ratio reaches 6.However,for the separated crack,its impact remains significant even when the LC/B ratio exceeds 16.The appearance of fine crack at the edge of the footing results in a decrease in the magnitude Nσγof up to 45%,indicating a substantial reduction in the stability of the footing.The failure patterns are presented and discussed in detail for various cases in this study to examine the effect of surface cracks on the strip footing and to address the extent of the plastic collapse.展开更多
The Hefei Basin of eastern China developed in response to uplift of the Dabie Orogen,and zircon dating can be used to assess the exhumation history of the orogen.Zircons were collected from samples of the Lower Jurass...The Hefei Basin of eastern China developed in response to uplift of the Dabie Orogen,and zircon dating can be used to assess the exhumation history of the orogen.Zircons were collected from samples of the Lower Jurassic Fanghushan Formation and Middle Jurassic Sanjianpu Formation in the southern Hefei Basin,and mica-quartz schist and biotite granite gneiss from the Susong Complex of the Dabie Orogen.The zircon U-Pb dating was undertaken using laser ablation-inductively coupled plasma-mass spectrometry.The detrital zircons from conglomerates of the Fanghushan Formation and from clasts within the conglomerates have age-frequency distributions with the main clusters between 2.0 and 1.8 Ga,similar to age data of the Susong Complex.On the other hand,the zircons of the Fanghushan Formation do not show the age cluster at 1000–900 Ma that characterizes zircons in the underlying metasediments of the lower Paleozoic Foziling Group.A cluster of Triassic zircon ages also appears in the arkosic sandstones of the Fanghushan Formation.These data indicate that the provenance of the Fanghushan Formation was a mixture of high-pressure(HP)and ultrahigh-pressure(UHP)Triassic metamorphic rocks,Paleozoic magmatic rocks,and the Susong Complex,but not the lower Paleozoic Foziling Group even though it directly underlies the sediments of the Hefei Basin.Two samples from the Sanjianpu Formation show zircon age clusters at 797 and 791 Ma(middle Neoproterozoic)and 226 Ma(Triassic),and again,these are markedly different from the age clusters that characterize the Foziling Group.It seems,therefore,that despite the Foziling Group being at the surface in the underwater depositional area of the Hefei Basin,it was not exposed in the source area of the Hefei basinal sediments during the Jurassic,and there are two possible reasons for this.First,the exhumation of the Dabie Orogen was directed partly towards the north,in the process of which some of the Foziling Group was covered.Second,the Susong Complex rocks became involved in the development of an accretionary wedge,thus covering some of the Foziling Group during the process of subduction.展开更多
This article reviews the current status on the dynamic behavior of highly stressed rocks under disturbances.Firstly,the experimental apparatus,methods,and theories related to the disturbance dynamics of deep,high-stre...This article reviews the current status on the dynamic behavior of highly stressed rocks under disturbances.Firstly,the experimental apparatus,methods,and theories related to the disturbance dynamics of deep,high-stress rock are reviewed,followed by the introduction of scholars’research on deep rock deformation and failure from an energy perspective.Subsequently,with a backdrop of highstress phenomena in deep hard rock,such as rock bursts and core disking,we delve into the current state of research on rock microstructure analysis and residual stresses from the perspective of studying the energy storage mechanisms in rocks.Thereafter,the current state of research on the mechanical response and the energy dissipation of highly stressed rock formations is briefly retrospected.Finally,the insufficient aspects in the current research on the disturbance and failure mechanisms in deep,highly stressed rock formations are summarized,and prospects for future research are provided.This work provides new avenues for the research on the mechanical response and damage-fracture mechanisms of rocks under high-stress conditions.展开更多
The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(R...The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(RCZ) is built. The formula for an ultimate cutting force is established based on the limit equilibrium principle. The relationship between digital drilling parameters(DDP) and the c-φ parameter(DDP-cφ formula, where c refers to the cohesion and φ refers to the internal friction angle) is derived, and the response of drilling parameters and cutting ratio to the strength parameters is analyzed. The drillingbased measuring method for the c-φ parameter of rock is constructed. The laboratory verification test is then completed, and the difference in results between the drilling test and the compression test is less than 6%. On this basis, in-situ rock drilling tests in a traffic tunnel and a coal mine roadway are carried out, and the strength parameters of the surrounding rock are effectively tested. The average difference ratio of the results is less than 11%, which verifies the effectiveness of the proposed method for obtaining the strength parameters based on digital drilling. This study provides methodological support for field testing of rock strength parameters.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52204084)the Open Research Fund of the State Key Laboratory of Coal Resources and safe Mining,CUMT,China(No.SKLCRSM 23KF004)+3 种基金the Interdisciplinary Research Project for Young Teachers of USTB(Fundamental Research Funds for the Central Universities),China(No.FRF-IDRY-GD22-002)the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange and Growth Program,China(No.QNXM20220009)the National Key R&D Program of China(Nos.2022YFC2905600 and 2022 YFC3004601)the Science,Technology&Innovation Project of Xiongan New Area,China(No.2023XAGG0061)。
文摘Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude.To investigate the correlation between the rock mass properties and maximum horizontal stress,the three-dimensional(3D)stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted,a newly defined characteristic parameter C_(ERP)was proposed as an indicator for evaluating the structural properties of rock masses,and a fuzzy relation matrix was established using the information distribution method.The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth.There is no remarkable correlation between the elastic modulus,Poisson's ratio and depth,and the distribution of data points is scattered and messy.Moreover,there is no obvious relationship between the rock quality designation(RQD)and depth.The maximum horizontal stress σ_(H) is a function of rock properties,showing a certain linear relationship with the C_(ERP)at the same depth.In addition,the overall change trend of σ_(H) determined by the established fuzzy identification method is to increase with the increase of C_(ERP).The fuzzy identification method also demonstrates a relatively detailed local relationship betweenσ_H and C_(ERP),and the predicted curve rises in a fluctuating way,which is in accord well with the measured stress data.
基金the support of the National Natural Science Foundation of China(Grant No.42207199)Scientific Research Project of Education of Zhejiang Province(No.Y202351343)+1 种基金Zhejiang Postdoctoral Scientific Research Project(Grant Nos.ZJ2022155,ZJ2022156)Zhejiang Province International Science and Technology Cooperation Base Open Fund Project(IBGDP-2023-01)。
文摘The squeezing deformation of surrounding rock is an important factor restricting the safe construction and long-term operation of tunnels when a tunnel passes through soft strata with high ground stress.Under such soft rock geological conditions,the large deformation of the surrounding rock can easily lead to the failure of supporting structures,including shotcrete cracks,spalling,and steel arch distortion.To improve the lining support performance during the large deformation of squeezed surrounding rock,this work selects aluminum foam with densities of 0.25 g/cm3,0.42 g/cm3 and 0.61 g/cm3 as the buffer layer material and carries out uniaxial confined compression tests.Through the evaluation and analysis of energy absorption and the comparison of the yield pressure of aluminum foam with those of other cushioning materials and yield pressure support systems,the strength,deformation and energy absorption of aluminum foam with a density of 0.25 g/cm3 meet the yield pressure performance requirements.The numerical model of the buffer layer yielding support system is then established via the finite element analysis software ABAQUS,and the influence of the buffer layer setting on the lining support is analyzed.Compared with the conventional support scheme,the addition of an aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining.The maximum and minimum principal stresses of the primary support are reduced by 13%and 15%,respectively.The maximum and minimum principal stresses of the secondary lining are reduced by 15%and 12%,respectively,and the displacement deformation of the secondary lining position is reduced by 15%.In summary,the application of aluminum foam buffer layer can reduce the stress and deformation of the primary support and secondary lining,improve the stress safety of the support and reduce the deformation of the support.
文摘In hilly regions,the existence of surface cracks in rock mass induces a potential threat to structural stability.Thus,the present research aims to explore the impact of surface cracks on the loadbearing capacity of strip footing placed on the rock mass.By taking into account the various boundary constraints across the surface of crack edges,the study investigates the presence of two categories of surface cracks,namely(1)separated crack,and(2)fine crack.The lower bound limit analysis is employed in conjunction with the finite element method(LBFELA)to conduct the numerical analysis.In order to evaluate rock mass yielding,the power conic programming(PCP)method is utilized to implement the generalized Hoek-Brown(GHB)failure criterion.The stability of the strip footing is analyzed by determining the bearing capacity factor(Nσγ),which is presented in the form of design charts by varying the strength parameters of rock,including the Geological Strength Index(GSI),Hoek-Brown material parameter(mi),Disturbance factor(D),and Normalised Uniaxial Compressive Strength(σci/γB),whereγis the unit weight of rock mass,and B is the width of strip footing.The study also investigates the impact of cracks on strip footings,considering different positions of the crack(LC)and depths of the crack(DC).The results demonstrate that the influence of the fine crack is only noticeable until the LC/B ratio reaches 6.However,for the separated crack,its impact remains significant even when the LC/B ratio exceeds 16.The appearance of fine crack at the edge of the footing results in a decrease in the magnitude Nσγof up to 45%,indicating a substantial reduction in the stability of the footing.The failure patterns are presented and discussed in detail for various cases in this study to examine the effect of surface cracks on the strip footing and to address the extent of the plastic collapse.
基金supported by the National Natural Science Foundation of China(Grant Nos.41572186&41872216)。
文摘The Hefei Basin of eastern China developed in response to uplift of the Dabie Orogen,and zircon dating can be used to assess the exhumation history of the orogen.Zircons were collected from samples of the Lower Jurassic Fanghushan Formation and Middle Jurassic Sanjianpu Formation in the southern Hefei Basin,and mica-quartz schist and biotite granite gneiss from the Susong Complex of the Dabie Orogen.The zircon U-Pb dating was undertaken using laser ablation-inductively coupled plasma-mass spectrometry.The detrital zircons from conglomerates of the Fanghushan Formation and from clasts within the conglomerates have age-frequency distributions with the main clusters between 2.0 and 1.8 Ga,similar to age data of the Susong Complex.On the other hand,the zircons of the Fanghushan Formation do not show the age cluster at 1000–900 Ma that characterizes zircons in the underlying metasediments of the lower Paleozoic Foziling Group.A cluster of Triassic zircon ages also appears in the arkosic sandstones of the Fanghushan Formation.These data indicate that the provenance of the Fanghushan Formation was a mixture of high-pressure(HP)and ultrahigh-pressure(UHP)Triassic metamorphic rocks,Paleozoic magmatic rocks,and the Susong Complex,but not the lower Paleozoic Foziling Group even though it directly underlies the sediments of the Hefei Basin.Two samples from the Sanjianpu Formation show zircon age clusters at 797 and 791 Ma(middle Neoproterozoic)and 226 Ma(Triassic),and again,these are markedly different from the age clusters that characterize the Foziling Group.It seems,therefore,that despite the Foziling Group being at the surface in the underwater depositional area of the Hefei Basin,it was not exposed in the source area of the Hefei basinal sediments during the Jurassic,and there are two possible reasons for this.First,the exhumation of the Dabie Orogen was directed partly towards the north,in the process of which some of the Foziling Group was covered.Second,the Susong Complex rocks became involved in the development of an accretionary wedge,thus covering some of the Foziling Group during the process of subduction.
文摘目的 探讨七味白术散对糖尿病模型大鼠海马组织RhoA/ROCK2通路的作用,并探讨其改善糖尿病脑病的作用机制。方法 以高脂饲料结合STZ复制并筛选出符合条件的DE大鼠模型,随机分为模型组、七味白术散低、中、高剂量组、西药组。另设不造模的正常组。采用Morris水迷宫实验观察各组大鼠学习和空间记忆能力,用ELISA法检测海马组织中β-淀粉样蛋白42(β-amyloid protein 42,Aβ42)与磷酸化Tau蛋白(p-tau)含量,用RT-PCR法和Western blot检测海马样本中突触相关蛋白Syn、突触后致密物质PSD95(Postsynaptic density protein-95,PSD95)、RhoA、ROCK2的表达水平。结果 在检测各海马样本中Syn、PSD95、RhoA及ROCK2相对表达后,发现七味白术散干预4周后,模型组与正常组比较:RhoA、ROCK2表达水平显著升高,Syn、PSD95表达水平显著下降,差异有统计学意义(P<0.01),提示DE大鼠海马组织中的RhoA/ROCK2信号通路被抑制。中剂量组与模型组比较后发现:RhoA、ROCK2表达水平显著下降,Syn、PSD95表达水平显著上升,差异有统计学意义(P<0.01),表明七味白术散可能通过抑制RhoA/ROCK2通路,并调节突触可塑性。结论 七味白术散可能是通过抑制RhoA/ROCK2信号通路并上调突触可塑性来改善患有DE的大鼠。
基金supported by the National Natural Science Foundation of China(Nos.52004015,51874014,and 52311530070)the fellowship of China National Postdoctoral Program for Innovative Talents(No.BX2021033)+1 种基金the fellowship of China Postdoctoral Science Foundation(Nos.2021M700389 and 2023T0025)the Fundamental Research Funds for the Central Universities of China(No.FRF-IDRY-20-003,Interdisciplinary Research Project for Young Teachers of USTB).
文摘This article reviews the current status on the dynamic behavior of highly stressed rocks under disturbances.Firstly,the experimental apparatus,methods,and theories related to the disturbance dynamics of deep,high-stress rock are reviewed,followed by the introduction of scholars’research on deep rock deformation and failure from an energy perspective.Subsequently,with a backdrop of highstress phenomena in deep hard rock,such as rock bursts and core disking,we delve into the current state of research on rock microstructure analysis and residual stresses from the perspective of studying the energy storage mechanisms in rocks.Thereafter,the current state of research on the mechanical response and the energy dissipation of highly stressed rock formations is briefly retrospected.Finally,the insufficient aspects in the current research on the disturbance and failure mechanisms in deep,highly stressed rock formations are summarized,and prospects for future research are provided.This work provides new avenues for the research on the mechanical response and damage-fracture mechanisms of rocks under high-stress conditions.
基金supported by the National Key Research and Development Program of China(No.2023YFC2907600)the National Natural Science Foundation of China(Nos.42077267,42277174 and 52074164)+2 种基金the Natural Science Foundation of Shandong Province,China(No.ZR2020JQ23)the Opening Project of State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology(No.KFJJ21-02Z)the Fundamental Research Funds for the Central Universities,China(No.2022JCCXSB03).
文摘The technology of drilling tests makes it possible to obtain the strength parameter of rock accurately in situ. In this paper, a new rock cutting analysis model that considers the influence of the rock crushing zone(RCZ) is built. The formula for an ultimate cutting force is established based on the limit equilibrium principle. The relationship between digital drilling parameters(DDP) and the c-φ parameter(DDP-cφ formula, where c refers to the cohesion and φ refers to the internal friction angle) is derived, and the response of drilling parameters and cutting ratio to the strength parameters is analyzed. The drillingbased measuring method for the c-φ parameter of rock is constructed. The laboratory verification test is then completed, and the difference in results between the drilling test and the compression test is less than 6%. On this basis, in-situ rock drilling tests in a traffic tunnel and a coal mine roadway are carried out, and the strength parameters of the surrounding rock are effectively tested. The average difference ratio of the results is less than 11%, which verifies the effectiveness of the proposed method for obtaining the strength parameters based on digital drilling. This study provides methodological support for field testing of rock strength parameters.
