The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is c...The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.展开更多
From the geological structure of the columnar jointed rock mass, a visual model was established in software AUTOCAD by programming based on the algorithm of the Voronoi diagram. Furthermore, a program to convert the A...From the geological structure of the columnar jointed rock mass, a visual model was established in software AUTOCAD by programming based on the algorithm of the Voronoi diagram. Furthermore, a program to convert the AUTOCAD model into 3DEC (3-dimensional distinct element code) model was developed, and a numerical model was established in 3DEC. Moreover, the results of triaxial compression tests of columnar jointed rock masses were simulated numerically. The REV (representative element volume) scale was studied, and the result shows that the REV size is 3 m × 3 m. The proposed approach, the established model and the numerical simulation were applied to study the macro-mechanical properties and the equivalent strength parameters of the columnar jointed rock mass. The numerical simulation results are in good accordance with the in-situ test results.展开更多
Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume cont...Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume contraction during cooling.In this paper,substantial field work was performed to study the geological characteristics of irregular columnar jointed basalt on the left bank dam foundation in the Baihetan Hydropower Station,where the columnar jointed rock mass is extensively exposed due to excavation.The quantitative measurements of the sizing of polygonal crack pattern of columnar joints and assessment of their degree of irregularity were summarized.Considering the irregularity of polygonal crack pattern,a modified Voronoi polygon(MVP)method was developed to model the special polygonal crack pattern of columnar joints.The new polygonal pattern obtained by the MVP method consists of a large number of irregular polygons,of which the degree of irregularity is consistent with the field measurement results.This method can reproduce the rapid evolution from an initial ideal regular hexagonal pattern to a final actual irregular polygonal pattern as the degree of irregularity increases.The compression tests of columnar jointed rock mass with different irregularity show that the geometric irregularity has a great influence on its mechanical properties.This numerical construction method provides a reliable way to reconstruct columnar joint structure with specific polygonal crack pattern,which is consistent with onsite columnar jointed basalt.展开更多
Irregular columnar jointed structure is a primary irregular columnar morphological tensile fracture. In order to study the geometric features of irregular columnar joints and the new problems in geotechnical engineeri...Irregular columnar jointed structure is a primary irregular columnar morphological tensile fracture. In order to study the geometric features of irregular columnar joints and the new problems in geotechnical engineering, hydraulic and hydropower engineering caused by columnar jointed basaltic mass, Voronoi graph from geometry was introduced to simulate the irregular columnar jointed basaltic mass at Baihetan hydraulic station. Discrete element software UDEC was used to simulate the whole process of rigid bearing plate test. Anisotropic constitutive of columnar joints was adopted to analyze the stress diffusion of rock mass at dam base of Baihetan. The results show that, the compaction property and hysteresis effect are well simulated based on discrete element simulation of Voronoi joint structure by UDEC. Four stages of cyclic loading and unloading process are imaged clearly. The results from in situ rigid bearing plate tests are explicated and the stress diffusion rule of anisotropic body is affected by structure surface. The elements in the stress state of 4-5 MPa are the most, about more than 35% of the total. Appropriate constitutive must be proposed to columnar jointed rock mass with different styles. It has important significance to realize the nonlinear mechanical behavior of irregular columnar jointed basaltic mass.展开更多
Columnar joints are regular columnar primary magmatic structure with polygonal cross sections developed in volcanic rocks which are commonly induced in cooling basaltic larva with low viscosity and high fluidity.In re...Columnar joints are regular columnar primary magmatic structure with polygonal cross sections developed in volcanic rocks which are commonly induced in cooling basaltic larva with low viscosity and high fluidity.In recent years,typical columnar joints in acidic volcanic rocks have been discovered in many other regions in China,including Quzhou area in Zhejiang Province,Siping and Shanmen area in Jilin Province.The latest studies on columnar joints revealed a different point of view on the展开更多
The pure Mg with columnar crystals was prepared by directional solidification,and the effect of process parameters on the crystal orientation and tensile properties was studied.Moreover,the microstructure evolution du...The pure Mg with columnar crystals was prepared by directional solidification,and the effect of process parameters on the crystal orientation and tensile properties was studied.Moreover,the microstructure evolution during tensile deformation was analyzed by electron backscatter diffraction(EBSD)technology.Furthermore,the slip within adjacent grains and grain boundary strain were discussed using the bicrystal model theory.The results show that the microstructure of the pure Mg at a pulling rate of 200μm/s is columnar polycrystal with growth orientation concentrated in<022ˉ5>,and no transverse grain boundaries can be seen.In addition,the Schmid factors(SFs)of basalslips in columnar crystals are higher than 0.43 under tensile stress.Moreover,the geometric compatibility factor of slip systems on both sides of grain boundaries is greater than 0.7,showing good strain coordination ability of grain boundaries.Therefore,the elongation of the directionally solidified pure Mg is as high as 53%at room temperature.展开更多
目的观察评估直肠黏膜柱状缝合(Block)术联合聚桂醇注射在治疗女性直肠前突中的临床疗效和安全性。方法该研究回顾性分析2022年1月至2023年12月在南京医科大学附属逸夫医院接受治疗的90例女性直肠前突患者。按手术治疗方式分为三组:Bloc...目的观察评估直肠黏膜柱状缝合(Block)术联合聚桂醇注射在治疗女性直肠前突中的临床疗效和安全性。方法该研究回顾性分析2022年1月至2023年12月在南京医科大学附属逸夫医院接受治疗的90例女性直肠前突患者。按手术治疗方式分为三组:Block术联合聚桂醇注射术(BP组)30例、单纯Block术(B组)30例和传统吻合器痔上黏膜环切术(procedure for prolapse and hemorrhoids,PPH)术(H组)30例。比较三组患者的一般临床资料,围术期各项指标、围术期患者Longo′s排便梗阻综合征(Longo′s ODS)评分、手术前后直肠前突程度、手术前后肛门直肠测压相关指标、手术疗效及围术期并发症情况。结果H组患者术中出血量显著高于B组和BP组(P<0.05)。BP组在术后24 h VAS评分和住院时间方面优于H组和B组(P<0.05)。术前三组患者的Longo′s ODS评分、直肠前突深度、肛管静息压和残余压差异无统计学意义(P>0.05);术后BP组的Longo′s ODS评分和直肠前突深度显著优于B组和H组(P<0.05)。术后肛管静息压和残余压在三组间差异无统计学意义(P>0.05),但BP组更接近正常范围。BP组的总体显效率为93.3%,高于B组的73.3%和H组的66.7%(P<0.05);三组患者并发症发生率差异无统计学意义(P>0.05)。结论Block术联合聚桂醇注射术是治疗女性直肠前突的安全有效的方法,疗效优于单纯行PPH术及Block术,可有效恢复女性直肠生理解剖形态,改善患者临床症状。展开更多
基金Projects(42307192,41831278)supported by the National Natural Science Foundation of ChinaProject(CKWV20231175/KY)supported by the CRSRI Open Research Program,China。
文摘The special columnar jointed structure endows rocks with significant anisotropy,accurately grasping the strength and deformation properties of a columnar jointed rock mass(CJRM)under complex geological conditions is crucial for related engineering safety.Combined with the irregular jointed networks observed in the field,artificial irregular CJRM(ICJRM)samples with various inclination angles were prepared for triaxial tests.The results showed that the increase in confining pressure can enhance the ability of the ICJRM to resist deformation and failure,and reduce the deformation and strength anisotropic degrees.Considering the field stress situation,the engineering parts with an inclination angle of 30°−45°need to be taken seriously.Four typical failure modes were identified,and the sample with an inclination angle of 15°showed the same failure behavior as the field CJRM.Traditional and improved joint factor methods were used to establish empirical relationships for predicting the strength and deformation of CJRM under triaxial stress.Since the improved joint factor method can reflect the unique structure of CJRM,the predictive ability of the empirical relationship based on the improved method is better than that based on the traditional joint factor method.
基金Projects(50911130366, 50979030) supported by the National Natural Science Foundation of China
文摘From the geological structure of the columnar jointed rock mass, a visual model was established in software AUTOCAD by programming based on the algorithm of the Voronoi diagram. Furthermore, a program to convert the AUTOCAD model into 3DEC (3-dimensional distinct element code) model was developed, and a numerical model was established in 3DEC. Moreover, the results of triaxial compression tests of columnar jointed rock masses were simulated numerically. The REV (representative element volume) scale was studied, and the result shows that the REV size is 3 m × 3 m. The proposed approach, the established model and the numerical simulation were applied to study the macro-mechanical properties and the equivalent strength parameters of the columnar jointed rock mass. The numerical simulation results are in good accordance with the in-situ test results.
基金Projects(51621006,51779251)supported by the National Natural Science Foundation of China。
文摘Columnar jointed rock mass with unique geometric and geological properties is one spectacular example of geometrical order in nature.Columnar joints are generally accepted to be formed by spatially uniform volume contraction during cooling.In this paper,substantial field work was performed to study the geological characteristics of irregular columnar jointed basalt on the left bank dam foundation in the Baihetan Hydropower Station,where the columnar jointed rock mass is extensively exposed due to excavation.The quantitative measurements of the sizing of polygonal crack pattern of columnar joints and assessment of their degree of irregularity were summarized.Considering the irregularity of polygonal crack pattern,a modified Voronoi polygon(MVP)method was developed to model the special polygonal crack pattern of columnar joints.The new polygonal pattern obtained by the MVP method consists of a large number of irregular polygons,of which the degree of irregularity is consistent with the field measurement results.This method can reproduce the rapid evolution from an initial ideal regular hexagonal pattern to a final actual irregular polygonal pattern as the degree of irregularity increases.The compression tests of columnar jointed rock mass with different irregularity show that the geometric irregularity has a great influence on its mechanical properties.This numerical construction method provides a reliable way to reconstruct columnar joint structure with specific polygonal crack pattern,which is consistent with onsite columnar jointed basalt.
基金Projects(50979030, 50911130366) supported by the National Natural Science Foundation of ChinaProject(2009B14014) supported by the Fundamental Research Funds for the Central Universities in China
文摘Irregular columnar jointed structure is a primary irregular columnar morphological tensile fracture. In order to study the geometric features of irregular columnar joints and the new problems in geotechnical engineering, hydraulic and hydropower engineering caused by columnar jointed basaltic mass, Voronoi graph from geometry was introduced to simulate the irregular columnar jointed basaltic mass at Baihetan hydraulic station. Discrete element software UDEC was used to simulate the whole process of rigid bearing plate test. Anisotropic constitutive of columnar joints was adopted to analyze the stress diffusion of rock mass at dam base of Baihetan. The results show that, the compaction property and hysteresis effect are well simulated based on discrete element simulation of Voronoi joint structure by UDEC. Four stages of cyclic loading and unloading process are imaged clearly. The results from in situ rigid bearing plate tests are explicated and the stress diffusion rule of anisotropic body is affected by structure surface. The elements in the stress state of 4-5 MPa are the most, about more than 35% of the total. Appropriate constitutive must be proposed to columnar jointed rock mass with different styles. It has important significance to realize the nonlinear mechanical behavior of irregular columnar jointed basaltic mass.
文摘Columnar joints are regular columnar primary magmatic structure with polygonal cross sections developed in volcanic rocks which are commonly induced in cooling basaltic larva with low viscosity and high fluidity.In recent years,typical columnar joints in acidic volcanic rocks have been discovered in many other regions in China,including Quzhou area in Zhejiang Province,Siping and Shanmen area in Jilin Province.The latest studies on columnar joints revealed a different point of view on the
基金Projects(51775099,51675092)supported by the National Natural Science Foundation of ChinaProjects(E2021501019,E2022501001,E2022501006)supported by the Natural Science Foundation of Hebei Province,China。
文摘The pure Mg with columnar crystals was prepared by directional solidification,and the effect of process parameters on the crystal orientation and tensile properties was studied.Moreover,the microstructure evolution during tensile deformation was analyzed by electron backscatter diffraction(EBSD)technology.Furthermore,the slip within adjacent grains and grain boundary strain were discussed using the bicrystal model theory.The results show that the microstructure of the pure Mg at a pulling rate of 200μm/s is columnar polycrystal with growth orientation concentrated in<022ˉ5>,and no transverse grain boundaries can be seen.In addition,the Schmid factors(SFs)of basalslips in columnar crystals are higher than 0.43 under tensile stress.Moreover,the geometric compatibility factor of slip systems on both sides of grain boundaries is greater than 0.7,showing good strain coordination ability of grain boundaries.Therefore,the elongation of the directionally solidified pure Mg is as high as 53%at room temperature.
文摘目的观察评估直肠黏膜柱状缝合(Block)术联合聚桂醇注射在治疗女性直肠前突中的临床疗效和安全性。方法该研究回顾性分析2022年1月至2023年12月在南京医科大学附属逸夫医院接受治疗的90例女性直肠前突患者。按手术治疗方式分为三组:Block术联合聚桂醇注射术(BP组)30例、单纯Block术(B组)30例和传统吻合器痔上黏膜环切术(procedure for prolapse and hemorrhoids,PPH)术(H组)30例。比较三组患者的一般临床资料,围术期各项指标、围术期患者Longo′s排便梗阻综合征(Longo′s ODS)评分、手术前后直肠前突程度、手术前后肛门直肠测压相关指标、手术疗效及围术期并发症情况。结果H组患者术中出血量显著高于B组和BP组(P<0.05)。BP组在术后24 h VAS评分和住院时间方面优于H组和B组(P<0.05)。术前三组患者的Longo′s ODS评分、直肠前突深度、肛管静息压和残余压差异无统计学意义(P>0.05);术后BP组的Longo′s ODS评分和直肠前突深度显著优于B组和H组(P<0.05)。术后肛管静息压和残余压在三组间差异无统计学意义(P>0.05),但BP组更接近正常范围。BP组的总体显效率为93.3%,高于B组的73.3%和H组的66.7%(P<0.05);三组患者并发症发生率差异无统计学意义(P>0.05)。结论Block术联合聚桂醇注射术是治疗女性直肠前突的安全有效的方法,疗效优于单纯行PPH术及Block术,可有效恢复女性直肠生理解剖形态,改善患者临床症状。
