首页|正融冰川碎屑冰冻体剪切强度劣化机制研究

正融冰川碎屑冰冻体剪切强度劣化机制研究

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受到气候变暖的影响,青藏高原冰川剪切滑动带中的碎屑冰冻体存在融化风险,这严重影响了冰川的抗剪强度和稳定性.为了研究融化过程对碎屑冰冻体剪切力学特性的影响,引入融冰率定量评估融化程度,对正融碎屑冰冻体试样开展了室内直剪试验.基于试验结果提出了正融碎屑冰冻体的有限-离散元数值模型并进行了对比验证,研究了融冰率和碎石含量对碎屑冰冻体剪切力学行为的影响规律.结果表明:融化过程显著降低了峰值剪切强度、黏聚力和内摩擦角;强度参数与融冰率的关系可用线性准则表达;正碎屑冰冻体剪切强度急剧劣化的主因是孔隙冰融化导致的冻土-孔隙冰界面黏聚力降低;当融冰率从2％增加到4％,试样变形模式由应变软化过渡为应变硬化,破坏模式由粗糙的"锯齿状"过渡为平滑的"圆弧状";随着碎石含量增加,碎屑冰冻体剪切强度明显降低,降低幅度随融冰率的增加而减小.该研究可作为冰川稳定性评价的有益补充.
Mechanism of shear strength degradation of subglacial debris under thawing
Affected by global warming,the subglacial debris on the Qinghai-Xizang Plateau in China is transforming from a frozen state into a thawing state,seriously affecting the glacier shear strength and glacier stability.In order to study the influence of thawing on the shear properties of subglacial debris,this paper introduced a new variable,the thawing rate,to quantitatively evaluate the amount of melted ice,and direct shear tests were carried out on thawing samples.Subsequently,a numerical model was established based on the finite-discrete element method to study the effects of thawing rate and gravel content on the shear behavior of subglacial debris.The results show that the thawing process significantly reduces the peak shear stress,cohesion,and inner friction angle.The relationship between shear strength parameters and thawing rate can be expressed using a linear relationship.The analysis of the factors affecting the shear strength parameters of thawing subglacial debris suggests that the reduction in the contribution of cementitious force can be responsible for strength degeneration.As the thawing rate increases from 2％to 4％,the deformation mode transitions from strain-softening to strain-hardening,and the failure mode shifts from rough serrated mode to smooth circular arc mode.Additionally,an increase in gravel content leads to a significant decrease in the shear strength of subglacial debris.However,the reduction range decreases as the thawing rate increases.This study provides valuable insights for evaluating the stability of glaciers by considering the effects of thawing on the shear properties of subglacial debris.

subglacial debristhawingdirect shear testshear behaviorfinite-discrete element

孟秋杰、宋宜祥、黄达、马文著、钟助、岑夺丰

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河北工业大学土木与交通学院,天津 300401

长安大学地质工程与测绘学院,陕西西安 710064

北京科技大学土木与资源工程学院,北京 100083

碎屑冰冻体 融化 直剪试验 剪切力学行为 有限-离散元

国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金国家自然科学基金河北省自然科学基金河北省自然科学基金

42272331U23A202579422771874197229742007276D2021202001D2020202002

2024

10.16285/j.rsm.2023.1013

岩土力学
中国科学院武汉岩土力学研究所

岩土力学

CSTPCD北大核心
影响因子：1.614
ISSN：1000-7598
年,卷(期)：2024.45(1)
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