气候变化领域集成服务门户(CCPortal): A temperature-and stress-controlled failure criterion for ice-filled permafrost rock joints

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DOI	10.5194/tc-12-3333-2018
	A temperature-and stress-controlled failure criterion for ice-filled permafrost rock joints
	Mamot P.; Weber S.; Schröder T.; Krautblatter M.
发表日期	2018
ISSN	19940416
卷号	12 期号:10
英文摘要	Instability and failure of high mountain rock slopes have significantly increased since the 1990s coincident with climatic warming and are expected to rise further. Most of the observed failures in permafrost-affected rock walls are likely triggered by the mechanical destabilisation of warming bedrock permafrost including ice-filled joints. The failure of ice-filled rock joints has only been observed in a small number of experiments, often using concrete as a rock analogue. Here, we present a systematic study of the brittle shear failure of ice and rock-ice interfaces, simulating the accelerating phase of rock slope failure. For this, we performed 141 shearing experiments with rock-ice-rock q sandwich samples at constant strain rates (10-3s-1) provoking ice fracturing, under normal stress conditions ranging from 100 to 800kPa, representing 4-30m of rock overburden, and at temperatures from-10 to-0.5°C, typical for recent observed rock slope failures in alpine permafrost. To create close to natural but reproducible conditions, limestone sample surfaces were ground to international rock mechanical standard roughness. Acoustic emission (AE) was successfully applied to describe the fracturing behaviour, anticipating rock-ice failure as all failures are predated by an AE hit increase with peaks immediately prior to failure. We demonstrate that both the warming and unloading (i.e. reduced overburden) of ice-filled rock joints lead to a significant drop in shear resistance. With a temperature increase from-10 to-0.5°C, the shear stress at failure reduces by 64%-78% for normal stresses of 100-400kPa. At a given temperature, the shear resistance of rock-ice interfaces decreases with decreasing normal stress. This can lead to a self-enforced rock slope failure propagation: as soon as a first slab has detached, further slabs become unstable through progressive thermal propagation and possibly even faster by unloading. Here, we introduce a new Mohr-Coulomb failure criterion for ice-filled rock joints that is valid for joint surfaces, which we assume similar for all rock types, and which applies to temperatures from-8 to-0.5°C and normal stresses from 100 to 400kPa. It contains temperature-dependent friction and cohesion, which decrease by 12%°C-1 and 10%°C-1 respectively due to warming and it applies to temperature and stress conditions of more than 90% of the recently documented accelerating failure phases in permafrost rock walls. © 2018 Author(s).
学科领域	bedrock; cohesion; concrete; friction; joint; limestone; permafrost; shear stress; slope failure; unloading; wall rock; warming
语种	英语
scopus关键词	bedrock; cohesion; concrete; friction; joint; limestone; permafrost; shear stress; slope failure; unloading; wall rock; warming
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119047
作者单位	Department of Landslide Research, Technical University of Munich, Munich, 80333, Germany; Department of Geography, University of Zurich, Zurich, 8057, Switzerland; Computer Engineering and Networks Laboratory, ETH Zurich, Zurich, 8092, Switzerland
推荐引用方式 GB/T 7714	Mamot P.,Weber S.,Schröder T.,et al. A temperature-and stress-controlled failure criterion for ice-filled permafrost rock joints[J],2018,12(10).
APA	Mamot P.,Weber S.,Schröder T.,&Krautblatter M..(2018).A temperature-and stress-controlled failure criterion for ice-filled permafrost rock joints.Cryosphere,12(10).
MLA	Mamot P.,et al."A temperature-and stress-controlled failure criterion for ice-filled permafrost rock joints".Cryosphere 12.10(2018).