The improved granular mixtures are widely used as the fillings of railway 8ubgrade, and in order to investigate the effect of coarse grain content on granular mixtures, a series of field tests were conducted. The expe...The improved granular mixtures are widely used as the fillings of railway 8ubgrade, and in order to investigate the effect of coarse grain content on granular mixtures, a series of field tests were conducted. The experimental results indicate that the permeability coefficient increases significantly with the increment of granite gravel content, especially in the range of 60%-70%. Thcrc exists a coarse grain content limit defined as 53%-58.5% to reform the permeable granular skeleton. Beyond this limit, the permeable granular skeleton is efficiently formed, and the macro pores between the separate gravels are partially filled, which is the explanation lbr the permeability increase. The investigations indicate the subgrade resistance modulus （ks0, Ev2, and Evd） depends on the granite gravel content, and the resistance modulus increases significantly beyond granite gravel content of 50%. The skeletons of granitc gravel clayey sand mixture change in the long-term deformation objected to the train-induced dynamic load, which involves three main repeated and circular deformation stages. Generally, the long-time deformation is explained as the gravel crushing and filling the internal porous space with crushed gravel fragments. Through these investigations, the C40-G60 or C30-G70 is recommended as an optimum soil mixture for the good permeability and high resistance modulus.展开更多
In this paper, we report an integrated study of trace element, U-Pb age and Hf isotopic composition of zircons from alkali feldspar granites, granodiorites and diorite enclaves in a recently discovered ring complex at...In this paper, we report an integrated study of trace element, U-Pb age and Hf isotopic composition of zircons from alkali feldspar granites, granodiorites and diorite enclaves in a recently discovered ring complex at Lianghe in western Yunnan, Chi na. The granitoids showed identical U-Pb ages of 127, 115 and 122 Ma, from felsic to mafic, but had different zircon trace el ements and Hf isotopic compositions. Trace element content decreased with a gradual increase in εHf(t) values of ?9.1 to ?5.4, ?4.5 to 0, and 3.6 to 6.2, respectively. Results indicate that changes in zircon trace elements generally correlate with changes in Hf isotope signatures within single samples and among various granitoids. These relationships reflect the mixing of felsic and mafic magmas. Evidence indicates that depleted mantle-derived mafic magma underplating caused ancient crustal melting, and then formed large-scale granites in Lianghe during the Early Cretaceous. These granodiorites were formed mainly by the mix ing of mafic magma and granitic magma.展开更多
基金Project(51378514)supported by the National Natural Science Foundation of China
文摘The improved granular mixtures are widely used as the fillings of railway 8ubgrade, and in order to investigate the effect of coarse grain content on granular mixtures, a series of field tests were conducted. The experimental results indicate that the permeability coefficient increases significantly with the increment of granite gravel content, especially in the range of 60%-70%. Thcrc exists a coarse grain content limit defined as 53%-58.5% to reform the permeable granular skeleton. Beyond this limit, the permeable granular skeleton is efficiently formed, and the macro pores between the separate gravels are partially filled, which is the explanation lbr the permeability increase. The investigations indicate the subgrade resistance modulus （ks0, Ev2, and Evd） depends on the granite gravel content, and the resistance modulus increases significantly beyond granite gravel content of 50%. The skeletons of granitc gravel clayey sand mixture change in the long-term deformation objected to the train-induced dynamic load, which involves three main repeated and circular deformation stages. Generally, the long-time deformation is explained as the gravel crushing and filling the internal porous space with crushed gravel fragments. Through these investigations, the C40-G60 or C30-G70 is recommended as an optimum soil mixture for the good permeability and high resistance modulus.
基金supported by China Geological Survey (Grant No. 1212010784007)
文摘In this paper, we report an integrated study of trace element, U-Pb age and Hf isotopic composition of zircons from alkali feldspar granites, granodiorites and diorite enclaves in a recently discovered ring complex at Lianghe in western Yunnan, Chi na. The granitoids showed identical U-Pb ages of 127, 115 and 122 Ma, from felsic to mafic, but had different zircon trace el ements and Hf isotopic compositions. Trace element content decreased with a gradual increase in εHf(t) values of ?9.1 to ?5.4, ?4.5 to 0, and 3.6 to 6.2, respectively. Results indicate that changes in zircon trace elements generally correlate with changes in Hf isotope signatures within single samples and among various granitoids. These relationships reflect the mixing of felsic and mafic magmas. Evidence indicates that depleted mantle-derived mafic magma underplating caused ancient crustal melting, and then formed large-scale granites in Lianghe during the Early Cretaceous. These granodiorites were formed mainly by the mix ing of mafic magma and granitic magma.
