冻土变形破坏过程与其局部应变特征发展规律有着密切联系,研究应变局部化发展规律有助于揭示其变形破坏机理,为实际工程提供理论依据。本文结合冻土平面应变试验结果及离散单元法,研究土体细观参数对其局部应变特征的影响。根据不同温度和应变速率条件下平面应变试验数据结果,采用“试错法”确定接触黏结模型在不同条件下的细观参数,结果表明:应力–应变曲线的峰值应力及其对应的轴向应变值基本一致,但在应变软化阶段,数值模拟结果相较于试验结果发展较快,这主要是由于接触黏结模型中不考虑土颗粒间胶结冰对转动的抵抗作用所致;剪切带的宽度、倾角及残余强度的试验和模拟值基本一致,结合库伦解的基本形式建立的细观摩擦系数与内摩擦角的量化关系能够准确描述土体的剪切带倾角,这表明细观参数中的摩擦系数是影响土体最终破坏形态的主要因素。
The deformation and failure process of frozen soil is closely related to the development law of its local strain characteristics. Studying the law of strain localization helps to reveal its deformation and failure mechanism, providing more theoretical basis for practical engineering. This article combines the results of plane strain tests on frozen soil and the Discrete Element Method to study the influence of soil microscopic parameters on its local strain characteristics. Based on the results of plane strain test data under different temperature and strain rate conditions, the microscopic parameters of the linear contact bond model under different conditions are determined through the "trial and error method". Comparative analysis of experimental and numerical simulation results show that the peak stress and corresponding axial strain values of the macroscopic stress-strain curve are the same. Due to the fact that the interface of the linear contact bond model does not consider the resistance of frozen soil particles to rotation, the curve obtained by numerical simulation develops faster in the strain softening stage. The measured and simulated values of the width, inclination angle of the shear band and residual strength are basically consistent, indicating that the friction coefficient in the microscopic parameters is the main factor affecting the final failure form of the soil. By comparing the experimental and simulation results, it is further shown that the relationship between the friction coefficient and the internal friction angle can be described by establishing the quantitative relationship between the friction coefficient and the Shear band inclination angle in the basic form of Mohr-Coulomb solution.
[1] 陈曦,刘宗祺,崔柳生,等.一种用于PFC的砂土剪切带宽度自动识别方法[J].岩土工程学报,2022,44(增2):179-182. (Chen Xi, Liu Zongqi, Cui Liusheng, et al. An automatic identification method for width of shear band of sand in PFC simulations[J], Chinese Journal of Geotechnical Engineering, 2022,44(Supp.2):179-182.(in Chinese))
[2] 马巍, 王大雁. 冻土力学[M]. 北京: 科学出版社, 2014. (Ma Wei, Wang Dayan. Frozen soil mechanics[M]. Beijing: Science Press. 2014.(in Chinese))
[3] 吴紫汪, 马巍, 张长庆, 等. 冻结砂土的强度特性[J]. 冰川冻土, 1994(1):15-20.(Wu Ziwang, Ma Wei, Changqing Zhang, et al. Strength characteristics of frozen sandy soil[J]. Journal of Glaciology and Geocryology, 1994(1):15-20.(in Chinese))
[4] 雷乐乐, 谢艳丽, 王大雁, 等. 冻土静力学室内试验研究进展[J]. 冰川冻土, 2018, 40(4):802-811. (Lei Lele, Xie Yanli, Wang Dayan, et al. Laboratory studies of frozen soil statics: recent progress and prospect[J]. Journal of Glaciology and Geocryology, 2018, 40(4):802-811.(in Chinese))
[5] 吴超, 张淑娟, 周志伟,等. 围压路径对冻结粉质砂土变形行为及强度的影响研究[J].冰川冻土,2016,38(6):1575-1582. (Wu Chao, Zhang Shujuan, Zhou Zhiwei, et al. A study of the effect of confining pressure path on strength and deformation of frozen silty sand[J]. Journal of Glaciology and Geocryology, 2016, 38(6):1575-1582.(in Chinese))
[6] 齐吉琳, 马巍. 冻土的力学性质及研究现状[J]. 岩土力学, 2010, 31(1):133-143. (Qi Jilin, Ma Wei. State-of-art of research on mechanical properties of frozen soils[J]. Rock and Soil Mechanics, 2010, 31(1):133-143.(in Chinese).)
[7] Esmaeili-Falak M,Katebi H, Vadiati M, et al. Predicting triaxial compressive strength and Young's Modulus of frozen sand using artificial intelligence methods[J]. Journal of Cold Regions Engineering, 2019, 33(3):04019007.
[8] Tounsi H,Rouabhi A, Jahangir E, et al. Mechanical behavior of frozen metapelite: Laboratory investigation and constitutive modeling[J]. Cold Regions Science and Technology, 2020, 175: 103058.
[9] Sun, Z Z, Zhang, S J, Wang, Y P, et al. Mechanical behavior and microstructural evolution of frozen soils under the combination of confining pressure and water content[J]. Engineering Geology, 2022, 308(36):106819
[10] 马巍, 吴紫汪. 冻土三轴蠕变过程中结构变化的CT动态监测[J]. 冰川冻土, 1997, 19(1):52-57. (Ma Wei, Wu Ziwang. Monitoring the change of structures in frozen soil in triaxial creep process by CT[J]. Journal of Glaciology and Geocryology, 1997, 19(1):52-57. (in Chinesee))
[11] 张革,刘恩龙.基于CT动态扫描的冻土细观二元介质本构模型[J].岩土工程学报, 2023, 45(9): 1888-1896. (Zhang Ge, Liu Enlong. Binary-medium constitutive model for frozen soil Based on CT dynamic scanning[J]. Chinese Journal of Geotechnical Engineerinng. 2023, 45(9): 1888-1896. (in Chinese))
[12] Chen S J, Ma W, Li G Y. A novel approach for characterizing frozen soil damage based onmesostructure[J]. International Journal of Damage Mechanics, 2022, 31(3):444-463.
[13] Wen D Y, Jiang N S, Liu, C K, et al. Study of the Influence of Temperature Rise on the Microstructure of frozen soil based on SEM and MIP[J]. Journal of Materials in Civil Engineering, 2023, 35(13):05023001
[14] Li S Z, Tang L, Tian S, et al. Mechanical Modeling of Frozen Coarse-Grained Materials Incorporating Microscale Investigation[J]. Advances in Materials Science and Engineering, 2021(37):6639428.
[15] 周凤玺,赖远明.冻结砂土力学性质的离散元模拟[J].岩土力学, 2010, 31(12):4016-4020. (Zhou Fengxi, Lai Yuanming. Simulation of mechanical behavior for frozen sand clay by discrete element method[J]. Rock and Soil Mechanics, 2010, 31(12):4016-4020. (in Chinese))
[16] 尹楠,李双洋,裴万胜,等.冻结黏土三轴试验微观变形机理的离散元分析[J].冰川冻土, 2016, 38(1):178-185. (Yin Nan, Li Shuangyang, Pei Wansheng, et al. Microscopic deformation mechanisms of triaxial test of frozen clay analyz-ed by discrete element method[J]. Journal of Glaciology and Geocryology, 2016, 38(1):178-185. (in Chinese))
[17] 袁伟,姚晓亮,王文丽.基于离散元的冻结砂土三轴力学特性研究[J].冰川冻土, 2019, 41(6):1388-1396.(Yuan Wei, Yao Xiaoliang, Wang Wenli. Study on triaxial mechanical behaviors of frozen sand based on discrete element method[J]. Journal of Glaciology and Geocryology, 2019, 41(6):1388-1396. (in Chinese))
[18] 朱纪斐. 冻结砂土单轴试验的离散元模拟[D]. 安徽: 安徽理工大学, 2018. (Zhu Jifei. Discrete element simulation of Frozen Sandy Soil uniaxial test[D]. Anhui: Anhui University of Science and Technology. 2018(in Chinese))
[19] Yao X L, Wang W L, Zhang M Y, et al. Strain localization of a frozen sand under different test conditions[J]. Cold Regions Science and Technology,2021, 183(6):103226.
[20] Yang B D, Jiao Y, Lei S T.A study on the effects of microparameters on macroproperties for specimens created by bonded particles[J]. Engineering Computations, 2006, 23(6):607-631.
