Uniaxial compressive strength(UCS)of rock is an essential parameter in geotechnical engineering.Point load strength(PLS),P-wave velocity,and Schmidt hammer rebound number(SH)are more easily obtained than UCS and are e...Uniaxial compressive strength(UCS)of rock is an essential parameter in geotechnical engineering.Point load strength(PLS),P-wave velocity,and Schmidt hammer rebound number(SH)are more easily obtained than UCS and are extensively applied for the indirect estimation of UCS.This study collected 1080 datasets consisting of SH,P-wave velocity,PLS,and UCS.All datasets were integrated into three categories(sedimentary,igneous,and metamorphic rocks)according to lithology.Stacking models combined with tree-based models and linear regression were developed based on the datasets of three rock types.Model evaluation showed that the stacking model combined with random forest and linear regression was the optimal model for three rock types.UCS of metamorphic rocks was less predictable than that of sedimentary and igneous rocks.Nonetheless,the proposed stacking models can improve the predictive performance for UCS of metamorphic rocks.The developed predictive models can be applied to quickly predict UCS at engineering sites,which benefits the rapid and intelligent classification of rock masses.Moreover,the importance of SH,P-wave velocity,and PLS were analyzed for the estimation of UCS.SH was a reliable indicator for UCS evaluation across various rock types.P-wave velocity was a valid parameter for evaluating the UCS of igneous rocks,but it was not reliable for assessing the UCS of metamorphic rocks.展开更多
This research examines optimization of blasting parameters for economic production of granite aggregates in Ratcon and NSCE quarries located atIbadan,OyoState. Samples were collected from the study areas for the deter...This research examines optimization of blasting parameters for economic production of granite aggregates in Ratcon and NSCE quarries located atIbadan,OyoState. Samples were collected from the study areas for the determination of rock density and porosity. Schmidt hammer was used for in situ determination of rock hardness. Uniaxial compressive strength of in situ rock was estimated from the values obtained from Schmidt hammer rebound hardness test and density determined from laboratory test. Blasting data were collected from the study areas for optimization. Multiple regression analysis using computer aided solution SPSS (Statistical Package for the Social Sciences) was used to analyse data obtained from the laboratory test, field test and the study areas. The estimated mean uniaxial compressive strength value of NSCE is 240 MPa and that of Ratcon is 200 MPa and their average densities and average porosities are2.63g/cm3,2.55g/cm3, 1.88% and 2.25% respectively. Eleven parameters were input into the multiple regression analysis to generate the models. Two parameters out of eleven input parameters such as geometric volume of blast (Y1) and number of boulders generated after blasting (Y2) were dependent variables and the remaining nine such as X1 (Drill hole diameter), X2 (Drill hole depth), X3 (Spacing), X4 (Burden), X5 (Average charge per hole), X6 (Rock density), X7 (Porosity), X8 (Uniaxial compressive strength) and X9 (Specific charge) were input as independent variables. The results of the models show that out of the nine independent variables seven of them that is X1 (Borehole diameter), X2 (Borehole depth), X3 (Spacing), X4 (Burden), X5 (Average charge per hole), X8 (Uniaxial compressive strength) and X9 (Specific charge) have significant contribution to the models while X6 (Rock Density) and X7 (Porosity) have insignificant contribution they are therefore automatically deleted by the SPSS. The result of the models developed for the optimization reveals that blasting number 5 gives the required product at lowe展开更多
This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including fo...This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including foliated phyllite, schist, gneiss and marble(calcschist) were selected and examined.Discontinuity surveys were made along lines for each rock and evaluated with DIPS program. L-type Schmidt hammer was applied in the directions parallel and perpendicular to foliation during the field study. Several hand samples and rock blocks were collected during the field study for measurements of dry and saturated densities, dry and saturated unit weights and porosity, and for petrographic analysis and strength determination in laboratory. L-and N-type Schmidt hammers were applied in the directions perpendicular(anisotropy angle of 0°) and parallel(anisotropy angle of 90) to the foliation on selected blocks of phyllite, schist, gneiss and marble(calcschist). The phyllite and schist have higher porosity and lower density values than the other rocks. However, coarse crystalline gneiss and marble(calcschist) have higher rebound values and strengths, and they are classified as strong-very strong rocks. Generally, the rebound values in the direction perpendicular to the foliation are slightly higher than that in the direction parallel to foliation. Rebound values of N-type Schmidt hammer are higher than the L-type values except for phyllite. Sometimes, the rebound values of laboratory and field applications gave different results. This may result from variable local conditions such as minerals differentiation,discontinuities, water content, weathering degree and thickness of foliated structure.展开更多
The most heavily glacierized tropical range in the world– the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA).In this study,the decline of the Churup glacier(9°28’18"...The most heavily glacierized tropical range in the world– the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA).In this study,the decline of the Churup glacier(9°28’18"S;77°25’02"W)and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images(1948-2016),the Schmidt hammer rock test and lichenometric dating.It is shown that Churup glacier has lost the vast majority of its estimated LIA extent(1.05±0.1 km^2;45.0×10^6-57.4×10^6 m^3).The rate of glacier retreat is documented to vary in space(SE,SW and NW-facing slopes)and time,with the peak between 1986 and 1995.With an area of 0.045 km^2 in 2016,it is expected that the complete deglaciation of the Churup valley is inevitable in the near future.Recently(post-LIA)exposed bedrock surfaces have shown higher R-values(54.2-66.4,AVG 63.3,STDEV 2.9)compared to pre-LIA exposed surfaces(46.1-59.3,AVG 50.1,STDEV 4.9),confirming the links to the duration of rock weathering.The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l.,revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment.展开更多
6个团队将争夺世界最大垃圾焚烧发电厂的设计权近日,6个团队入围位于中国深圳的世界最大垃圾焚烧发电厂的设计竞赛。他们分别是Arup,Atkins,AECOM,Gerber Architekten,Schmidt Hammer Lassen with Gottlieb Paludan Architects以及深圳...6个团队将争夺世界最大垃圾焚烧发电厂的设计权近日,6个团队入围位于中国深圳的世界最大垃圾焚烧发电厂的设计竞赛。他们分别是Arup,Atkins,AECOM,Gerber Architekten,Schmidt Hammer Lassen with Gottlieb Paludan Architects以及深圳本地的汤桦建筑师事务所。展开更多
基金supported by the National Natural Science Foundation of China (No.52374153 and No.52074349)the Fundamental Research Funds for the Central Universities of Central South University (No.2023zzts0726).
文摘Uniaxial compressive strength(UCS)of rock is an essential parameter in geotechnical engineering.Point load strength(PLS),P-wave velocity,and Schmidt hammer rebound number(SH)are more easily obtained than UCS and are extensively applied for the indirect estimation of UCS.This study collected 1080 datasets consisting of SH,P-wave velocity,PLS,and UCS.All datasets were integrated into three categories(sedimentary,igneous,and metamorphic rocks)according to lithology.Stacking models combined with tree-based models and linear regression were developed based on the datasets of three rock types.Model evaluation showed that the stacking model combined with random forest and linear regression was the optimal model for three rock types.UCS of metamorphic rocks was less predictable than that of sedimentary and igneous rocks.Nonetheless,the proposed stacking models can improve the predictive performance for UCS of metamorphic rocks.The developed predictive models can be applied to quickly predict UCS at engineering sites,which benefits the rapid and intelligent classification of rock masses.Moreover,the importance of SH,P-wave velocity,and PLS were analyzed for the estimation of UCS.SH was a reliable indicator for UCS evaluation across various rock types.P-wave velocity was a valid parameter for evaluating the UCS of igneous rocks,but it was not reliable for assessing the UCS of metamorphic rocks.
文摘This research examines optimization of blasting parameters for economic production of granite aggregates in Ratcon and NSCE quarries located atIbadan,OyoState. Samples were collected from the study areas for the determination of rock density and porosity. Schmidt hammer was used for in situ determination of rock hardness. Uniaxial compressive strength of in situ rock was estimated from the values obtained from Schmidt hammer rebound hardness test and density determined from laboratory test. Blasting data were collected from the study areas for optimization. Multiple regression analysis using computer aided solution SPSS (Statistical Package for the Social Sciences) was used to analyse data obtained from the laboratory test, field test and the study areas. The estimated mean uniaxial compressive strength value of NSCE is 240 MPa and that of Ratcon is 200 MPa and their average densities and average porosities are2.63g/cm3,2.55g/cm3, 1.88% and 2.25% respectively. Eleven parameters were input into the multiple regression analysis to generate the models. Two parameters out of eleven input parameters such as geometric volume of blast (Y1) and number of boulders generated after blasting (Y2) were dependent variables and the remaining nine such as X1 (Drill hole diameter), X2 (Drill hole depth), X3 (Spacing), X4 (Burden), X5 (Average charge per hole), X6 (Rock density), X7 (Porosity), X8 (Uniaxial compressive strength) and X9 (Specific charge) were input as independent variables. The results of the models show that out of the nine independent variables seven of them that is X1 (Borehole diameter), X2 (Borehole depth), X3 (Spacing), X4 (Burden), X5 (Average charge per hole), X8 (Uniaxial compressive strength) and X9 (Specific charge) have significant contribution to the models while X6 (Rock Density) and X7 (Porosity) have insignificant contribution they are therefore automatically deleted by the SPSS. The result of the models developed for the optimization reveals that blasting number 5 gives the required product at lowe
文摘This paper aims to study the effect of anisotropy on strengths of several metamorphic rocks of southern(Cine) submassif of Menderes metamorphic massif in southwest Turkey. Four different metamorphic rocks including foliated phyllite, schist, gneiss and marble(calcschist) were selected and examined.Discontinuity surveys were made along lines for each rock and evaluated with DIPS program. L-type Schmidt hammer was applied in the directions parallel and perpendicular to foliation during the field study. Several hand samples and rock blocks were collected during the field study for measurements of dry and saturated densities, dry and saturated unit weights and porosity, and for petrographic analysis and strength determination in laboratory. L-and N-type Schmidt hammers were applied in the directions perpendicular(anisotropy angle of 0°) and parallel(anisotropy angle of 90) to the foliation on selected blocks of phyllite, schist, gneiss and marble(calcschist). The phyllite and schist have higher porosity and lower density values than the other rocks. However, coarse crystalline gneiss and marble(calcschist) have higher rebound values and strengths, and they are classified as strong-very strong rocks. Generally, the rebound values in the direction perpendicular to the foliation are slightly higher than that in the direction parallel to foliation. Rebound values of N-type Schmidt hammer are higher than the L-type values except for phyllite. Sometimes, the rebound values of laboratory and field applications gave different results. This may result from variable local conditions such as minerals differentiation,discontinuities, water content, weathering degree and thickness of foliated structure.
基金the Ministry of Education, Youth and Sports of the Czech Republic within the framework of the National Sustainability Programme Ⅰ(NPU Ⅰ), Grant No. LO1415
文摘The most heavily glacierized tropical range in the world– the Peruvian Cordillera Blanca-has been losing ice since the end of the Little Ice Age(LIA).In this study,the decline of the Churup glacier(9°28’18"S;77°25’02"W)and associated processes were documented employing multi-proxy approach including the analysis of remotely sensed images(1948-2016),the Schmidt hammer rock test and lichenometric dating.It is shown that Churup glacier has lost the vast majority of its estimated LIA extent(1.05±0.1 km^2;45.0×10^6-57.4×10^6 m^3).The rate of glacier retreat is documented to vary in space(SE,SW and NW-facing slopes)and time,with the peak between 1986 and 1995.With an area of 0.045 km^2 in 2016,it is expected that the complete deglaciation of the Churup valley is inevitable in the near future.Recently(post-LIA)exposed bedrock surfaces have shown higher R-values(54.2-66.4,AVG 63.3,STDEV 2.9)compared to pre-LIA exposed surfaces(46.1-59.3,AVG 50.1,STDEV 4.9),confirming the links to the duration of rock weathering.The Lichenometric dating is applied to recently exposed areas and elevations above 4800 m a.s.l.,revealing only limited reliability and agreement with the age of deglaciation estimated from remotely-sensed images in such an environment.
文摘6个团队将争夺世界最大垃圾焚烧发电厂的设计权近日,6个团队入围位于中国深圳的世界最大垃圾焚烧发电厂的设计竞赛。他们分别是Arup,Atkins,AECOM,Gerber Architekten,Schmidt Hammer Lassen with Gottlieb Paludan Architects以及深圳本地的汤桦建筑师事务所。
