Research on Mechanical Properties of Glacial Tills in Purang Region of Xizang
-
摘要:
为揭示西藏普兰地区冰碛土的力学行为,对天然状态表层冰碛土开展法向压力为100~400 kPa的现场直剪试验,对96%压实度冰碛土开展法向压力为100~400 kPa的室内大型直剪试验及围压为100~400 kPa的室内大型三轴试验. 试验结果表明:西藏普兰地区冰碛土91.7%压实度的天然状态下内聚力为11.0 kPa,内摩擦角为41.0°;在96%压实度时,内聚力为9.4~11.2 kPa,内摩擦角在45.3°~46.7°,且室内大型三轴试验所得强度参数高于大型直剪试验;96%压实度下冰碛土峰值强度高于天然状态,但初始阶段模量小于天然状态冰碛土;各级围压下,冰碛土应力-应变曲线均呈现软化特性,峰值应变随围压的增加先增大后减小;修正的邓肯-张模型可以较好地描述冰碛土偏应力与轴向应变关系,并体现普兰地区冰碛土的应变软化特性.
Abstract:To reveal the mechanical properties of glacial tills in the Purang region of Xizang, in-situ direct shear tests with normal pressures from 100 kPa to 400 kPa were carried out on surface glacial tills in a natural state, and laboratory large-scale direct shear tests with normal pressures from 100 kPa to 400 kPa and large-scale triaxial tests with confining pressures from 100 kPa to 400 kPa were carried out on glacial tills with the compaction degree of 96%. The results show that the cohesion of surface glacial tills with a compaction degree of 91.7% is 11.0 kPa, and the internal angle of friction is 41.0°. The cohesion of glacial tills with a compaction degree of 96% is between 9.4 kPa and 11.2 kPa; the internal angle of friction is between 45.3° and 46.7°; the strength parameters obtained from laboratory large-scale triaxial tests are higher than those from large-scale direct shear tests. The peak strengths of glacial tills with a compaction degree of 96% are higher than those in a natural state, but the initial moduli are lower than those in a natural state. The stress–strain curve of glacial tills exhibits softening characteristics under various confining pressures, and the peak strain shows a trend of an increase followed by a decrease with the increase of confining pressures. The modified Duncan-Chang model can well describe the relationship between deviatoric stress and axial strain of glacial tills and reflect the strain softening characteristics of glacial tills in the Purang region.
-
Key words:
- glacial till /
- mechanical property /
- compaction degree /
- shear strength
-
表 1 各地区冰碛土强度参数
Table 1. Strength parameters of glacial tills in different regions
-
[1] 蒋德旺,崔鹏,王姣,等. 细粒含量对冰碛土抗剪强度影响的实验研究[J]. 冰川冻土,2019,41(1): 129-139.JIANG Dewang, CUI Peng, WANG Jiao, et al. Experimental study on the effect of shear strength of moraine soil with fine grain content[J]. Journal of Glaciology and Geocryology, 2019, 41(1): 129-139. [2] 牛向东,侯克鹏,孙华芬. 基于关键块理论的井下泥石流机理力学模型研究[J/OL]. 西南交通大学学报,2024:1-12. (2024-03-29). http://kns.cnki.net/KCMS/detail/detail.aspx?filename=XNJT20240326005&dbname=CJFD&dbcode=CJFQ. [3] 梁俊岩,王成汤,陈娱,等. 降雨诱发作用下太和镇冰碛土古滑坡变形特征及其复活机制[J]. 科学技术与工程,2025,25(4): 1370-1377. doi: 10.12404/j.issn.1671-1815.2309686Liang Junyan, Wang Chengtang, Chen Yu, et al. Deformation characteristics of moraine soil ancient landslide and its resurrection mechanism in Taihe Town under rainfall-induced effects[J]. Science Technology and Engineering, 2025, 25(4): 1370-1377. doi: 10.12404/j.issn.1671-1815.2309686 [4] 李奇龙,周佳庆,李长冬,等. 气候变化环境下青藏高原含冰冰碛土斜坡水热力耦合特性与长期稳定性[J]. 地质科技通报,2025,44(1): 112-125.LI Qilong, ZHOU Jiaqing, LI Changdong, et al. Coupling characteristics and stability evolution of ice-rich moraine soil slopes on the Tibetan Plateau under climate change[J]. Bulletin of Geological Science and Technology, 2025, 44(1): 112-125. [5] 刘佳诺,李明俐,姜元俊,等. 基于PFC2D的冻融循环作用下冰碛土微观损伤研究[J]. 地球科学,2025:1-18.Liu Jianuo, Li Mingli, Jiang Yuanjun, et al. Microscopic damage evolution of moraine soils under freeze-thaw cycles based on PFC2D simulation[J]. Earth Science, 2025: 1-18. [6] 刘振兴,王姣,崔鹏,等. 藏东南地区冰碛土强度特性对温度响应试验研究[J]. 地球科学,2025,50(1): 322-335.Liu Zhenxing, Wang Jiao, Cui Peng, et al. Experimental study on response of strength characteristics of glacier tills to temperature in southeast Tibet. Earth Science, 50(1): 322-335. [7] INSLEY A E, HILLIS S F. Triaxial shear characteristics of a compacted glacial till under unusually high confining pressures[C]//Sixth International Conference On Soil Mechanics and Foundation Engineering. 1965, 1: 244−248. [8] 蒙进,屈智炯. 高压下冰碛土的颗粒破碎及应力应变关系[J]. 成都科技大学学报,1989,21(1): 17-22,56.MENG Jin, QU Zhijiong. Stress-strain behaviour of glacial till under high confining pressure[J]. Advanced Engineering Sciences, 1989, 21(1): 17-22,56. [9] 谢春庆,刘都鹏. 冰碛层中架空块碎石成因及处理分析[J]. 路基工程,2006(6): 34-37. doi: 10.3969/j.issn.1003-8825.2006.06.016XIE Chunqing, LIU Dupeng. Cause and treatment analysis of overhead block gravel in moraine layer[J]. Subgrade Engineering, 2006(6): 34-37. doi: 10.3969/j.issn.1003-8825.2006.06.016 [10] MCGOWN A, MCARTHUR A A. Morainic soil deposits and their use in lower cost roads[J]. Roads and Road Construction London, 1971, 49(587): 88-96. [11] 屈智炯,刘开明,肖晓军,等. 冰碛土微观结构、应力应变特性及其模型研究[J]. 岩土工程学报,1992,14(6): 19-28. doi: 10.3321/j.issn:1000-4548.1992.06.003QU Zhijiong, LIU Kaiming, XIAO Xiaojun, et al. Study of microstructure, stress-strain behavior and constitutive model of till[J]. Chinese Journal of Geotechnical Engineering, 1992, 14(6): 19-28. doi: 10.3321/j.issn:1000-4548.1992.06.003 [12] SPRINGMAN S M, JOMMI C, TEYSSEIRE P. Instabilities on moraine slopes induced by loss of suction: a case history[J]. Géotechnique, 2003, 53(1): 3-10. [13] 徐鼎平,汪斌,江龙剑,等. 冰碛土三轴数值模拟试验方法探讨[J]. 岩土力学,2008,29(12): 3466-3470. [14 吕士展,汪稔,胡明鉴,等. 玉龙雪山西麓原状冰碛土CT扫描试验研究[J]. 岩土力学,2014,35(6): 1593-1599,1622.XU Dingping, WANG Bin, JIANG Longjian, et al. Study of methods of triaxial numerical simulation test of glacial till[J]. Rock and Soil Mechanics, 2008, 29(12): 3466-3470. LÜ Shizhan, WANG Ren, HU Mingjian, et al. Computerized tomography(CT) scanning test research on intact moraine soil on west side of Yulong snow mountain[J]. Rock and Soil Mechanics, 2014, 35(6): 1593-1599, 1622. [14] 王杜江. 藏东南察达沟谷冰碛堤工程适宜性研究[J]. 铁道工程学报,2021,38(6): 21-25,74. doi: 10.3969/j.issn.1006-2106.2021.06.005WANG Dujiang. Research on the engineering suitability of moraine dike in chada valley of southeast Tibet[J]. Journal of Railway Engineering Society, 2021, 38(6): 21-25,74. doi: 10.3969/j.issn.1006-2106.2021.06.005 [15] 冯俊德,李建国,汪稔,等. 云南某铁路冰碛土大型直剪强度特性试验研究[J]. 岩土力学,2008,29(12): 3205-3210. doi: 10.3969/j.issn.1000-7598.2008.12.005FENG Junde, LI Jianguo, WANG Ren, et al. Large scale direct shear test on strength behavior of railway moraine soils in Yunnan[J]. Rock and Soil Mechanics, 2008, 29(12): 3205-3210. doi: 10.3969/j.issn.1000-7598.2008.12.005 [16] 郭喜峰,王中豪. 冰碛土现场大尺寸蠕变试验研究[J]. 岩土工程学报,2023,45(增1): 144-147.GUO Xifeng, WANG Zhonghao. Large-scale field creep tests on moraine soil[J]. Chinese Journal of Geotechnical Engineering, 2023, 45(S1): 144-147. [17] 程强,郭喜峰. 泸定大渡河桥冰碛土的结构及现场剪切试验研究[J]. 水文地质工程地质,2019,46(4): 126-133.CHENG Qiang, GUO Xifeng. Soil structure and in-site shear test of moraine soil near the Xingkang Bridge over the Daduhe River in Luding[J]. Hydrogeology & Engineering Geology, 2019, 46(4): 126-133. [18] 程强,郭喜峰,杨莹辉. 泸定大渡河桥冰碛土剪切蠕变特性试验研究[J]. 工程科学与技术,2019,51(3): 26-35.CHENG Qiang, GUO Xifeng, YANG Yinghui. Experimental study of shear creep characteristic of moraine soil in Dadu River bridge in Luding[J]. Advanced Engineering Sciences, 2019, 51(3): 26-35. [19] 中华人民共和国工业和信息化部. 现场直剪试验规程:YS/T 5221—2019[S]. 北京:中国计划出版社,2020. [20] 中华人民共和国住房和城乡建设部. 土工试验方法标准:GB/T 50123—2019[S]. 北京:中国计划出版社,2019. [21] 中国民用航空局. 3民用机场岩土工程设计规范:MH/T 5027−201 [S]. 北京:中国民航出版社,2013. [22] 姜程程,范文,苑伟娜. 基于环剪试验的含钙质结核古土壤剪切特性[J]. 西南交通大学学报,2021,56(4): 809-817.JIANG Chengcheng, FAN Wen, YUAN Weina. Shear properties of paleosol containing calcareous concretions based on ring shear tests[J]. Journal of Southwest Jiaotong University, 2021, 56(4): 809-817. [23] 余云燕,罗崇亮,崔文豪,等. 冻融循环下盐渍土热质传递及盐冻胀机理[J/OL]. 西南交通大学学报,2023:1-8. (2023-10-07). http://kns.cnki.net/KCMS/detail/detail.aspx?filename=XNJT20230926009&dbname=CJFD&dbcode=CJFQ. [24] 赖远明,程红彬,高志华,等. 冻结砂土的应力-应变关系及非线性莫尔强度准则[J]. 岩石力学与工程学报,2007,26(8): 1612-1617. doi: 10.3321/j.issn:1000-6915.2007.08.011LAI Yuanming, CHENG Hongbin, GAO Zhihua, et al. Stress-strain relationships and nonlinear Mohr strength criterion of frozen sand clay[J]. Chinese Journal of Rock Mechanics and Engineering, 2007, 26(8): 1612-1617. doi: 10.3321/j.issn:1000-6915.2007.08.011 -