By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instr...By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.展开更多
Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ter...Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ternary CuO-PbO-Ag system,there is a eutectic reaction CuO+PbO+Ag=L at 750℃ and a composition of 12.04 mol.% Ag,16.35 mol.% CuO and 71.61 mol.% PbO.Two miscibility gaps near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in the ternary system.SEM and energy dispersive spectroscopy(EDS) confirm the presence of two liquid phases and the eutectic point.展开更多
目的探究H型原发性高血压(高血压)患者血清诱骗受体3(decoy receptor 3,DcR3)、含1型血小板反应蛋白基序的去整合素金属蛋白酶13(A disintegrin and metalloproteinase with A thrombospondin type 1 motif member 13,ADAMTS13)浓度与...目的探究H型原发性高血压(高血压)患者血清诱骗受体3(decoy receptor 3,DcR3)、含1型血小板反应蛋白基序的去整合素金属蛋白酶13(A disintegrin and metalloproteinase with A thrombospondin type 1 motif member 13,ADAMTS13)浓度与其心血管功能及预后的关系。方法选取大庆市人民医院2020年6月至2022年6月收治的132例高血压患者作为观察对象,根据同型半胱氨酸(homocysteine,Hcy)浓度分为非H型高血压组40例和H型高血压组92例,根据预后情况将H型高血压患者分为预后良好组和预后不良组,并选择同期来大庆市人民医院健康体检的成年人70名作为对照组。采用酶联免疫吸附试验法检测受试者血清中DcR3、ADAMTS13浓度,Pearson法分析血清中DcR3、ADAMTS13浓度与心血管功能指标的相关性,多因素Logistic回归分析H型高血压患者1年预后不良的影响因素。绘制受试者工作特征曲线(receiver operating characteristic curve,ROC)分析血清DcR3、ADAMTS13浓度对H型高血压患者1年预后不良的预测价值。结果与对照组[(122.28±32.34)mmHg(1 mmHg=0.133 kPa)、(48.16±8.65)mmHg、(8.59±1.25)mm、(118.34±34.25)g/m2、(1.48±0.34)g/L、(57.15±14.94)mg/L、(1.45±0.31)、70.28%±15.21%]比较,H型高血压组患者的收缩压[(139.35±38.21)mmHg]、脉压[(57.37±11.75)mmHg]、左心室后壁厚度(posterior wall thickness,PWT)[(11.69±2.00)mm]以及左心室质量指数(left ventricular mass index,LVMI)[(148.54±38.22)g/m2]显著升高,DcR3[(0.74±0.19)g/L]、ADAMTS13浓度[(14.13±4.62)mg/L]、二尖瓣舒张早期血流峰值/二尖瓣舒张晚期血流峰值(E-peak to A-peak of the mitral flow spectrum,E/A)(0.65±0.13)、左心室射血分数(left ventricular ejection fraction,LVEF)(64.26%±12.75%)显著降低,差异有统计学意义(P<0.05);与非H型高血压组患者组比较,H型高血压组患者的DcR3、ADAMTS13浓度及E/A显著降低,LVMI显著升高,差异有统计学意义(P<0.05)。H型高血压组患者血清中DcR3、ADAMTS13浓度均与收缩压、脉压和LVMI呈负相关(P<0.05),而与E/A、LVEF呈正相关(P<0.05)。预后不良组患者的年龄显著高于预后良好组,E/A(0.38±0.07)、DcR3[(0.45±0.13)g/L]、ADAMTS13浓度[(8.45±2.11)mg/L]显著低于预后良好组[0.75±0.11、(0.85±0.27)g/L、(16.25±4.85)mg/L],差异有统计学意义(P<0.05)。DcR3、ADAMTS13是H型高血压患者预后不良的保护因素(P<0.05)。血清DcR3、ADAMTS13浓度单独及二者联合预测H型高血压患者1年发生预后不良的曲线下面积(area under the curve,AUC)分别为0.906、0.844、0.950。结论H型高血压疾病患者血清DcR3、ADAMTS13浓度降低,与心血管功能及预后密切相关,对该疾病的预后评估有重要价值。展开更多
A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating...A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating geological disasters.This study conducted shear experiments on rough rock joints under displacement-controlled dynamic normal loads,investigating the shear behaviors of joints across varying initial normal loads,normal loading frequencies,and normal loading amplitudes.Experimental results showed that the peak/valley shear force values increased with initial normal loads and normal loading frequencies but showed an initial increase followed by a decrease with normal loading amplitudes.Dynamic normal loading can either increase or decrease shear strength,while this study demonstrates that higher frequencies lead to enhanced friction.Increased initial normal loading and normal loading frequency result in a gradual decrease in joint roughness coefficient(JRC)values of joint surfaces after shearing.Positive correlations existed between frictional energy dissipation and peak shear forces,while post-shear joint surface roughness exhibited a negative correlation with peak shear forces through linear regression analysis.This study contributes to a better understanding of the sliding responses and shear mechanical characteristics of rock joints under dynamic disturbances.展开更多
基金support of the National Basic Research 973 Program of China (No.2013CB036003)the National Natural Science Foundation of China (No.51374198)the National Natural Science Foundation young investigator grant program of China (Nos.51204163,51504247,and 51404255)
文摘By applying experimental method, the bolt stress and supporting mechanism is studied during the deformation process of a rock mass containing a weak interlayer. The force measuring bolt is installed manually and instrumented five pairs of symmetrical strain gauges. The experimental results show that the fully grouted bolt suffers tensile, compressive, bending and shear stress at the same time. The bolt stress evolution is closely related to the deformation stages of the rock mass which are very gradually varying stage, gradually varying stage at the pre-peak and suddenly varying stage at the post peak stage.The axial compressive stress in the bolt is mainly induced by the moment. Thus, in most cases the axial compressive stress is distributed on one side of the bolt. For axial stresses, induced by the axial force and the bending moment at the post-peak stage, three types of changing are observed, viz. increasingincreasing type, decreasing-increasing type and increasing-decreasing type. The stress characteristics of the bolt section in the weak interlayer are significantly different from those in the hard rock. The failure models of the anchored bolt are tensile failure and shear failure, respectively. The bolt not only provides constraints on the free surface of the rock mass, but also resists the axial and lateral loading by the bending moment. This study provides valuable guidelines for bolting support design and its safety assessment.
文摘Phase equilibrium in the ternary CuO-PbO-Ag system has been investigated using differential thermal analysis(DTA),thermogravimetry(TG),scanning electron microscopy(SEM) and X-ray diffraction(XRD) techniques.In the ternary CuO-PbO-Ag system,there is a eutectic reaction CuO+PbO+Ag=L at 750℃ and a composition of 12.04 mol.% Ag,16.35 mol.% CuO and 71.61 mol.% PbO.Two miscibility gaps near the two binary tie lines PbO-Ag and CuO-Ag were detected. No binary or ternary compound was detected in the ternary system.SEM and energy dispersive spectroscopy(EDS) confirm the presence of two liquid phases and the eutectic point.
基金Projects(51504247,52174092,51904290,52074259)supported by the National Natural Science Foundation of ChinaProject(BK20220157)supported by Natural Science Foundation of Jiangsu Province,China。
文摘目的探究H型原发性高血压(高血压)患者血清诱骗受体3(decoy receptor 3,DcR3)、含1型血小板反应蛋白基序的去整合素金属蛋白酶13(A disintegrin and metalloproteinase with A thrombospondin type 1 motif member 13,ADAMTS13)浓度与其心血管功能及预后的关系。方法选取大庆市人民医院2020年6月至2022年6月收治的132例高血压患者作为观察对象,根据同型半胱氨酸(homocysteine,Hcy)浓度分为非H型高血压组40例和H型高血压组92例,根据预后情况将H型高血压患者分为预后良好组和预后不良组,并选择同期来大庆市人民医院健康体检的成年人70名作为对照组。采用酶联免疫吸附试验法检测受试者血清中DcR3、ADAMTS13浓度,Pearson法分析血清中DcR3、ADAMTS13浓度与心血管功能指标的相关性,多因素Logistic回归分析H型高血压患者1年预后不良的影响因素。绘制受试者工作特征曲线(receiver operating characteristic curve,ROC)分析血清DcR3、ADAMTS13浓度对H型高血压患者1年预后不良的预测价值。结果与对照组[(122.28±32.34)mmHg(1 mmHg=0.133 kPa)、(48.16±8.65)mmHg、(8.59±1.25)mm、(118.34±34.25)g/m2、(1.48±0.34)g/L、(57.15±14.94)mg/L、(1.45±0.31)、70.28%±15.21%]比较,H型高血压组患者的收缩压[(139.35±38.21)mmHg]、脉压[(57.37±11.75)mmHg]、左心室后壁厚度(posterior wall thickness,PWT)[(11.69±2.00)mm]以及左心室质量指数(left ventricular mass index,LVMI)[(148.54±38.22)g/m2]显著升高,DcR3[(0.74±0.19)g/L]、ADAMTS13浓度[(14.13±4.62)mg/L]、二尖瓣舒张早期血流峰值/二尖瓣舒张晚期血流峰值(E-peak to A-peak of the mitral flow spectrum,E/A)(0.65±0.13)、左心室射血分数(left ventricular ejection fraction,LVEF)(64.26%±12.75%)显著降低,差异有统计学意义(P<0.05);与非H型高血压组患者组比较,H型高血压组患者的DcR3、ADAMTS13浓度及E/A显著降低,LVMI显著升高,差异有统计学意义(P<0.05)。H型高血压组患者血清中DcR3、ADAMTS13浓度均与收缩压、脉压和LVMI呈负相关(P<0.05),而与E/A、LVEF呈正相关(P<0.05)。预后不良组患者的年龄显著高于预后良好组,E/A(0.38±0.07)、DcR3[(0.45±0.13)g/L]、ADAMTS13浓度[(8.45±2.11)mg/L]显著低于预后良好组[0.75±0.11、(0.85±0.27)g/L、(16.25±4.85)mg/L],差异有统计学意义(P<0.05)。DcR3、ADAMTS13是H型高血压患者预后不良的保护因素(P<0.05)。血清DcR3、ADAMTS13浓度单独及二者联合预测H型高血压患者1年发生预后不良的曲线下面积(area under the curve,AUC)分别为0.906、0.844、0.950。结论H型高血压疾病患者血清DcR3、ADAMTS13浓度降低,与心血管功能及预后密切相关,对该疾病的预后评估有重要价值。
基金Projects(52174092,51904290)supported by the National Natural Science Foundation,ChinaProject(BK20220157)supported by the Natural Science Foundation of Jiangsu Province,China+1 种基金Project(232102321009)supported by Henan Province Science and Technology Key Project,ChinaProject(2022YCPY0202)supported by Fundamental Research Funds for the Central Universities,China。
文摘A comprehensive understanding of the dynamic frictional characteristics in rock joints under high normal load and strong confinement is essential for ensuring the safety of deep engineering construction and mitigating geological disasters.This study conducted shear experiments on rough rock joints under displacement-controlled dynamic normal loads,investigating the shear behaviors of joints across varying initial normal loads,normal loading frequencies,and normal loading amplitudes.Experimental results showed that the peak/valley shear force values increased with initial normal loads and normal loading frequencies but showed an initial increase followed by a decrease with normal loading amplitudes.Dynamic normal loading can either increase or decrease shear strength,while this study demonstrates that higher frequencies lead to enhanced friction.Increased initial normal loading and normal loading frequency result in a gradual decrease in joint roughness coefficient(JRC)values of joint surfaces after shearing.Positive correlations existed between frictional energy dissipation and peak shear forces,while post-shear joint surface roughness exhibited a negative correlation with peak shear forces through linear regression analysis.This study contributes to a better understanding of the sliding responses and shear mechanical characteristics of rock joints under dynamic disturbances.
