Appropriate rock characterization is beneficial in providing a reliable judgment on rock properties which is crucial for the design process of rock engineering applications.However,it can be difficult to obtain consis...Appropriate rock characterization is beneficial in providing a reliable judgment on rock properties which is crucial for the design process of rock engineering applications.However,it can be difficult to obtain consistent mechanical parameters due to substantial variations in rock properties.In this research,uniaxial compression tests on dolerite specimens collected from a gold mine in Western Australia showed substantial scatter in the results.Rock categorization based on the P-wave velocities is as accurate as the thin section analysis,which suggests that they can be used together to gain a more accurate initial understanding of the rock types before any laboratory testing.The quality of specimen preparation and rockemachine interaction greatly affect the test results.For instance,non-parallelness of loading platens can lead to considerable scatter of the testing results,which would be perceived as rock variability.It is suggested that the current testing standards should be modified towards a better control of the loading machine performance and equipment precision.Finally,the possibility of pre-existing microcracks in rock,neither detected by the thin section analysis nor by the ultrasonic measurement,must be examined by computed tomography(CT)scanning as they can affect the test results.This study will enhance our knowledge about the sources of variability in laboratory test results of rock which is essential for obtaining reliable data.展开更多
The purpose of this paper is to present a novel topology optimization approach to control precisely the output loads under static loads and harmonic excitations.We introduce the Artificial Bar Element(ABE)at the desig...The purpose of this paper is to present a novel topology optimization approach to control precisely the output loads under static loads and harmonic excitations.We introduce the Artificial Bar Element(ABE)at the designated output positions,where the output loads are equivalently measured and constrained with the nodal displacements of ABE.Optimization model is then formulated considering the output load constraints as well as the minimization of strain energy and dynamic displacement responses respectively under the static and dynamic conditions.The influences of the ABEs stiffness,different material usages of the design domain,widths of the output loads constraint intervals and variation ratios of output loads are discussed in detail.The proposed method is verified with several numerical examples with clear and reasonable load transfer paths.展开更多
基金the Curtin Strategic International Research Scholarship(CSIRS)and Mining Research Institute of Western Australia(MRIWA)-project M474 scholarshipthe Australian Research Council through project DP190103260.
文摘Appropriate rock characterization is beneficial in providing a reliable judgment on rock properties which is crucial for the design process of rock engineering applications.However,it can be difficult to obtain consistent mechanical parameters due to substantial variations in rock properties.In this research,uniaxial compression tests on dolerite specimens collected from a gold mine in Western Australia showed substantial scatter in the results.Rock categorization based on the P-wave velocities is as accurate as the thin section analysis,which suggests that they can be used together to gain a more accurate initial understanding of the rock types before any laboratory testing.The quality of specimen preparation and rockemachine interaction greatly affect the test results.For instance,non-parallelness of loading platens can lead to considerable scatter of the testing results,which would be perceived as rock variability.It is suggested that the current testing standards should be modified towards a better control of the loading machine performance and equipment precision.Finally,the possibility of pre-existing microcracks in rock,neither detected by the thin section analysis nor by the ultrasonic measurement,must be examined by computed tomography(CT)scanning as they can affect the test results.This study will enhance our knowledge about the sources of variability in laboratory test results of rock which is essential for obtaining reliable data.
基金supported by National Key Research and Development Program(No.2017YFB1102800)NSFC for Excellent Young Scholars(No.11722219)Key Project of NSFC(Nos.51790171,5171101743)
文摘The purpose of this paper is to present a novel topology optimization approach to control precisely the output loads under static loads and harmonic excitations.We introduce the Artificial Bar Element(ABE)at the designated output positions,where the output loads are equivalently measured and constrained with the nodal displacements of ABE.Optimization model is then formulated considering the output load constraints as well as the minimization of strain energy and dynamic displacement responses respectively under the static and dynamic conditions.The influences of the ABEs stiffness,different material usages of the design domain,widths of the output loads constraint intervals and variation ratios of output loads are discussed in detail.The proposed method is verified with several numerical examples with clear and reasonable load transfer paths.
