气候变化领域集成服务门户(CCPortal): A Weakening Rheology of Dry Granular Flows With Extensive Brittle Grain Damage in High-Speed Rotary Shear Experiments

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DOI	10.1029/2020GL087763
	A Weakening Rheology of Dry Granular Flows With Extensive Brittle Grain Damage in High-Speed Rotary Shear Experiments
	Hu W.; Chang C.S.; McSaveney M.; Huang R.; Xu Q.; Zheng Y.; Yu J.
发表日期	2020
ISSN	0094-8276
卷号	47 期号:11
英文摘要	The puzzle of the unexpectedly high mobility of large geophysical flows has been reported as solved many times since Albert Heim drew attention to it after a disastrous landslide at Elm, Switzerland. Many hypotheses have been proposed to explain the hypermobility; however, no consensus position has emerged in more than a century, and debate rages on. We show a new trend of dense granular flow behavior above average normal stress of 0.3 MPa with weakening at high strain rate, which may be explained by shear-thinning thixotropy. Experimental results for a given shear rate at normal stresses between 0.3 and 1 MPa show a bifurcation in shear-resistance behavior. The trend of all our data deviates obviously from the traditional rheological model. We identified three regions of dense granular flow: a static region, an inertial region, and a weakening region at increasing strain rate in grain flows that results in widespread grain breakage. The former two regions agree with the traditional rheological model established at lower normal stresses; however, instead of entering a collisional region, a weakening region appeared. For gravity flows, it is possible for unstable flows to occur for certain combinations of normal stress and shear strain rate. An underlying mechanism of grain crushing and grain crushing-induced special grain structure may greatly reduce the shear resistance due to thixotropy. The profound weakening provides a natural explanation for the observed high mobility in such geophysical behavior as the long runout of rock avalanches, fault weakening, impact-crater evolution, and pyroclastic flows. ©2020. American Geophysical Union. All Rights Reserved.
英文关键词	Confined flow; Crushing; Geophysics; Granular materials; Shear flow; Shear strain; Shear thinning; Average normal stress; Dense granular flows; Dry granular flows; Geophysical flows; High strain rates; Pyroclastic flows; Rheological modeling; Shear resistances; Strain rate; experimental design; experimental study; geophysical method; gravity flow; landslide; pyroclastic flow; rheology; rock avalanche; shear strain; strain rate; thixotropy; Elm; Glarus [Switzerland]; Switzerland; Ulmus
语种	英语
来源期刊	Geophysical Research Letters
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/170280
作者单位	State Key Laboratory of Geo-Hazard Prevention and Geo-Environment Protection, Chengdu University of Technology, Chengdu, China; Department of Civil Engineering, University of Massachusetts, Amherst, MA, United States; GNS Science, Lower Hutt, New Zealand
推荐引用方式 GB/T 7714	Hu W.,Chang C.S.,McSaveney M.,et al. A Weakening Rheology of Dry Granular Flows With Extensive Brittle Grain Damage in High-Speed Rotary Shear Experiments[J],2020,47(11).
APA	Hu W..,Chang C.S..,McSaveney M..,Huang R..,Xu Q..,...&Yu J..(2020).A Weakening Rheology of Dry Granular Flows With Extensive Brittle Grain Damage in High-Speed Rotary Shear Experiments.Geophysical Research Letters,47(11).
MLA	Hu W.,et al."A Weakening Rheology of Dry Granular Flows With Extensive Brittle Grain Damage in High-Speed Rotary Shear Experiments".Geophysical Research Letters 47.11(2020).