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The improvement of density measurement method of loose sedimentary based on large sample method in gravity survey |
GENG Tao1,2( ), FENG Fan3, DU Hui1,2, FENG Zhi-Han1,2, GUO Pei-Hong1,2 |
1. Xi’an Center of Geological Survey of CGS, Xi’an 710054,China 2. Northwest Geological Science and Technology Innovation Center, Xi’an 710054 3. Xi’an Northwest Nonferrous Geophysical and Geochemical Exploration Co., Ltd., Xi’an 710068,China |
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Abstract In the gravity survey, especially in the gravity survey of the Quaternary cover areas, it is of great significance to accurately determine the density of loose sediments for the correction, processing, inversion, interpretation and study of gravity data. For a long time, the density of loose sediments has always been determined by regular bulk sample method in the field of gravity survey. However, it is difficult for this method to obtain a regular sampling pit in field work. Therefore, there is a large error between the volume of sampling pit obtained from the calculation formula of regular shape and the volume of actual sampling pit, which leads to inaccurate measurement of density value of loose sediments. This paper presents a method which is the irregular hexahedron volume calculation method. This method is more suitable for the actual situation in the field, and can improve the traditional regular bulk sample method. This method can determine the density of loose sediments more precisely and raise the working efficiency.
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Received: 31 July 2020
Published: 01 March 2021
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Schematic diagram of large sample method
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Diagram of difference between actual sampling pit and theoretical sampling pit
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The numbering of the corner nodes and the surfaces of a hexahedral element, and the definition of the shape parameters
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Degeneration forms of hexahedral elements
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Coordinate system used to calculate the volume of tetrahedron
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A parallelepiped can be divided into six equal tetrahedrons
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Need to measure parameters in field work
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The known conditions of irregular quadrilateral and the side length to be calculated
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Interface of calculation program for large sample density
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Correct method of measuring side length
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