The lithologic composition of beds, their geometry, their trajectory, stacking patterns and hierarchies are used to interpret their depositional setting. The sedimentary " bed" is the basic unit,or fundamental building block of stratigraphy (Campbell, 1967). Nuclear engineering: Materials of engineering and construction.These are commonly layers of sedimentary rock separated by breaks called bedding planes. Published in Advances in Materials Science and Engineering ISSN 1687-8434 (Print) 1687-8442 (Online) Publisher Hindawi Limited Country of publisher United Kingdom LCC subjects Technology: Electrical engineering. This paper leads to a better understanding of the load transfer mechanism for the anchoring system in soft and hard composite strata and provides a reference for scientific support design and evaluation method. Under the same anchor length, the peak load and the displacement at the peak load decrease with the increase of layer numbers, but the reduction magnitude decreases. The greater the hard rock thickness, the larger the peak load. Therefore, the closer the hard rock is to the loading end, the greater the initial stiffness of the load-displacement curve is. As the hard to soft thickness ratio increases, the load peak and the displacement at the peak load increase.
The load-displacement curve shows the same initial stiffness for different hard to soft thickness ratios in HSCRS. As the soft-to-hard thickness ratio in SHCRS increases, the initial stiffness of the load-displacement curve and peak load decreases continuously. Under the same layer number, the shallower-soft and deeper-hard composite rock strata (SHCRS) have a higher bearing capacity and deformation resistance than the shallower-hard and deeper-soft composite rock strata (HSCRS). Lithological sequence, layer thickness ratio, and layer numbers are taken into consideration in numerical simulation models. The numerical result shows a close match with the experiment tests and the proposed model. Then, the nonlinear bond-slip relationship is put into the numerical model.
The nonlinear bond-slip relationship of bolt-grout interface that is anchored in soft rock and hard rock is obtained from laboratory test, respectively. A numerical study is presented in this paper on the pull-out behavior of fully grouted rock bolts in soft and hard composite rock strata. However, most of the current support is designed for homogeneous rock masses, which ignores the different anchoring effect in soft and hard composite rock strata. Soft and hard composite rock strata are frequently encountered in transportation, geotechnical, and underground engineering. Ning Li State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining & Technology, Xuzhou 221116, China Zhanguo Ma State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining & Technology, Xuzhou 221116, China Peng Gong State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining & Technology, Xuzhou 221116, China Fuzhou Qi State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining & Technology, Xuzhou 221116, China Tuo Wang State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining & Technology, Xuzhou 221116, China Shixing Cheng State Key Laboratory for Geomechanics and Deep Underground Engineering, School of Mechanics and Civil Engineering, China University of Mining & Technology, Xuzhou 221116, China DOI Journal volume & issue
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