Influence of Freezing-Thawing Cycles on Mechanical Properties of Tailing Soil at Yunnan-Guizhou Plateau
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摘要: 为研究尾矿力学指标在冻融循环过程中的弱化规律，基于冻融尾矿土的常规三轴固结不排水剪切试验，对冻融前后尾矿土的各项力学指标进行了分析. 首先对尾矿土试样进行开放条件下的冻融试验，设置0、1、5、10、15次冻融；然后对不同冻融次数下的尾矿土进行常规三轴固结不排水剪切试验，设置50、100、200、300 kPa 4组围压；最后基于试验结果，对抗剪强度、峰值抗剪强度及弹性模量等力学指标进行分析. 研究表明：冻融对尾矿土的力学性质影响显著，随着冻融次数的增加，其应力-应变关系曲线由应变软化型逐渐向加工硬化型发展；破坏形式由脆性剪切破坏转变为延性破坏，剪切过程中孔压负增长的趋势逐渐减弱至消失；抗剪强度指标、峰值抗剪强度及弹性模量逐渐降低，其中，尾矿土受第1次冻融的扰动最大，表现为有效凝聚力和有效内摩擦角分别降低了30.55%和6.33%；峰值抗剪强度下降比的平均值达42.66%，弹性模量下降比的平均值达33.61%；10次冻融后尾矿土的力学指标趋于稳定，从第10次到第15次冻融，有效凝聚力和有效内摩擦角分别降低2.94%和0.37%；峰值抗剪强度下降比的平均值和平均弹性模量下降比的平均值分别为2.53%和4.03%，建议采用冻融10次的力学指标作为工程设计的依据.Abstract: In order to study how the mechanical properties of tailing soil evolve during the freezing-thawing process in open environment, a series of triaxial consolidated undrained (CU) shear tests were carried out with different numbers of freezing-thawing cycles and confining pressures. In the tests, 0, 1, 5, 10 and 15 freezing-thawing cycles were set and the groups of confining pressures including 50, 100, 200 and 300 kPa were applied. Based on test results, the mechanical indexes, including the shear strength, the peak value of shear strength and elastic modulus are finally analyzed. The results indicate that the influence of freezing-thawing on mechanical properties of tailing soils is significant. As the number of freezing-thawing cycles increases, the stress-strain curves gradually transform from the strain-softening type into the work-hardening one, whereas the brittle failure pattern turns into plastic failure, and the negative growth of pore pressure during the shearing process becomes weak till disappears; the peak shear strength, cohesion, internal friction angle and elastic modulus gradually decrease; during the process, tailing soils are affected most by the first cycle of freezing-thawing, of which the effective cohesion and effective internal frictional angle is reduced by 30.55% and 6.33%, respectively; and the average reduction ratios of the peak shear strength and elastic modulus are 42.66% and 33.61%, respectively. The mechanical indexes of tailing soils tend to stabilize after 10 freezing-thawing cycles, and from 10 to 15 cycles of freezing-thawing, the effective cohesion and effective internal frictional angle are reduced by 2.94% and 0.37% respectively; and the average reduction values of the peak shear strength and elastic modulus are 2.53% and 4.03%, respectively. The mechanical indexes of 10 freezing-thawing cycles are proposed as the reference for engineering design.
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图 2 未经室内冻融处理的重塑尾矿土试样的电镜扫描图像
Figure 2. SEM images of remoulded tailing soil without indoor freezing-thawing treatment
图 3 冻融循环对试样体积的影响
Figure 3. Influence of freezing-thawing cycles on volume expansion of tailing soil
图 4 冻融循环次数对应力-应变关系曲线的影响
Figure 4. Influence of freezing-thawing cycles on stress-axial strain curve
图 5 冻融循环对尾矿土破坏形式的影响
Figure 5. Influence of freezing-thawing cycles on failure form of tailing soils
图 6 围压对孔压-轴向应变关系曲线的影响
Figure 6. Influence of confining pressure on pore pressure-axial strain curve
图 7 冻融循环次数对峰值抗剪强度的影响
Figure 7. Influence of freezing-thawing cycles on peak shear strength
表 1 尾矿土主要物理参数
Table 1. Mail physical parameters of tailing soils
比重 干密度/
（g•cm−3）孔隙比 液限 /% 塑限/% 天然含水
率/%塑限指数 /% 液限指数 可溶性盐
含量/%3.0 1.492 1.01 71 32 35 39 0.07 2～3 
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表 2 尾矿土X射线能谱分析结果
Table 2. EDS analysis results of tailing soil
% 项目 O C S Ca Si Fe Zn Al K Mg Mn 质量百分数 56.28 5.28 10.51 10.46 6.03 5.61 2.74 1.37 0.61 0.37 0.75 原子数目百分数 70.38 8.80 6.56 5.22 4.30 2.01 0.84 1.01 0.31 0.3 0.27
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表 3 不同冻融循环次数下有效黏聚力和有效内摩察角
Table 3. Effective cohesion and effective internal friction angle under different freezing-thawing cycles
N/次 c/kPa φ/（°） c'/kPa φ'/（°） 0 254.20 11.00 120.70 38.25 1 104.20 10.79 83.83 35.83 5 60.00 6.33 44.50 24.18 10 39.74 6.30 30.36 19.76 15 31.67 6.24 26.81 19.62
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表 4 不同冻融循环次数和围压下的弹性模量
Table 4. Elastic modulus under different freezing-thawing cycles and confining pressures
MPa N/次 围压 50 kPa 100 kPa 200 kPa 300 kPa 0 425 583 618 638 1 235 340 413 543 5 108 155 170 174 10 55 115 138 143 15 50 98 100 105
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尹光志,杨作亚,魏作安,等. 羊拉铜矿尾矿料的物理力学性质[J]. 重庆大学学报(自然科学版),2007,30(9): 117-122.YIN Guangzhi, YANG Zuoya, WEI Zuoan, et al. Physico-mechanical properties of YangLa-copper's tailing[J]. Journal of Chongqing University (Natural Science), 2007, 30(9): 117-122. 田文旗,谢旭阳. 我国尾矿库现状及安全对策的建议[J]. 中国矿山工程,2009,38(6): 42-49. doi: 10.3969/j.issn.1672-609X.2009.06.014TIAN Wenqi, XIE Xuyang. Tailing pond situation in China and safety countermeasures suggestion[J]. China Mine Engineering, 2009, 38(6): 42-49. doi: 10.3969/j.issn.1672-609X.2009.06.014 徐学祖, 王家澄, 张立新. 冻土物理学[M]. 北京: 科学出版社, 2001: 9-18. 刘庭发, 张鹏伟, 胡黎明. 含硫铜矿尾矿料的工程力学特性试验研究[J]. 岩土工程学报, 2013, 35(增刊1): 166-169.LIU Tingfa, ZHANG Pengwei, HU Liming. Experimental study on mechanical characteristics of copper tailing materials with sulfur content[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(S1): 166-169. ZHANG Q, YIN G, FAN X, et al. Loading capacity and deformation characteristics of tailings based on a fractal geometrical analysis of the particle microstructure[J]. Minerals, 2015, 5(1): 86-103. doi: 10.3390/min5010086 AUBERTIN M, RICARD J F, CHAPUIS P R. A predictive model for the water retention curve: application totailings from hard-rock mines[J]. Canadian Geotechnical Journal, 1999, 35(1): 55-69. RASSAM D W, WILLIAMS D J. Unsaturated hydraulic conductivity of mine tailings under wetting and drying conditions[J]. Geotechnical Testing Journal, 1999, 22(2): 138-146. HU L, WU H, ZHANG L, et al. Geotechnical properties of mine tailings[J]. Journal of Materials in Civil Engineering, 2016, 29(2): 04016220.1-04016220.10. ZHANG Z, MA W, FENG W, et al. Reconstruction of soil particle composition during freeze-thaw cycling:a review[J]. Pedosphere, 2016, 26(2): 167-179. doi: 10.1016/S1002-0160(15)60033-9 HAZIRBABA K, GULLU H. California bearing ratio improvement and freeze-thaw performance of fine-grained soils treated with geofiber and synthetic fluid[J]. Cold Regions Science & Technology, 2010, 63(1): 50-60. CHANG D, LIU J K. Review of the influence of freeze-thaw cycles on the physical and mechanical properties of soil[J]. Sciences in Cold and Arid Regions, 2013, 5(4): 457-460. doi: 10.3724/SP.J.1226.2013.00457 PARDINI G, GUIDI G V, PINI R, et al. Structure and porosity of smectiticmudrocks as affected by experimental wetting-drying cycles and freezing-thawing cycles[J]. Catena, 1996, 27(27): 149-165. 王伟, 池旭超, 张芳, 等. 冻融循环对滨海软土三轴应力应变曲线软化特性的影响[J]. 岩土工程学报, 2013, 35(增刊2): 140-144.WANG Wei, CHI Xuchao, ZHANG Fang, et al. Effect of freeze-thaw circles on softening behaviors of triaxial stress-strain curve of costal soft soils[J]. Chinese Journal of Geotechnical Engineering, 2013, 35(S2): 140-144. SHIBI T, KAMEI Takeshi. Effect of freeze-thaw cycles on the strength and physical properties of cement-stabilised soil containing recycled bassanite and coal ash[J]. Cold Regions Science and Technology, 2014, 106/107: 36-45. doi: 10.1016/j.coldregions.2014.06.005 严晗, 刘建坤, 王天亮. 冻融对粉砂土力学性能影响的试验研究[J]. 北京交通大学学报, 2013, 37(4): 73-77YAN Han, LIU Jiankun, WANG Tianliang. Experimental research of influences of freeze-thaw on the mechanical properties of silty sand[J]. Journal of Beijing Jiaotong University, 2013, 37(4): 73-77. 于琳琳,徐学燕,邱明国,等. 冻融作用对饱和粉质黏土抗剪性能的影响[J]. 岩土力学,2010,31(8): 2448-2452. doi: 10.3969/j.issn.1000-7598.2010.08.016YU Linlin, XU Xueyan, QIU Mingguo, et al. Influence of freeze-thaw on shear strength properties of saturated silty clay[J]. Rock and Soil Mechanics, 2010, 31(8): 2448-2452. doi: 10.3969/j.issn.1000-7598.2010.08.016 王大雁, 马巍, 常小晓, 等. 冻融循环作用对青藏粘土物理力学性质的影响[J]. 岩石力学与工程学报, 2005, 24（23）: 4313-4313.WANG Dayan, MA Wei, CHANG Xiaoxiao, et al. Physical-mechanical properties changes of Qinghai−Tibet clay due to cyclic freezing and thawing[J]. Chinese Journal of Rock Mechanics and Engineering, 2005. 24（23）: 4313-4319. 王林,张爽,彭少波. 冻融循环条件下武汉红土物理力学性质试验研究[J]. 安全与环境工程,2012,19(3): 138-142. doi: 10.3969/j.issn.1671-1556.2012.03.034WANG Lin, ZHANG Shuang, PENG Shaobo. Experimental studies on red clay soil in Wuhan under freeze-thaw cycle condition[J]. Safety and Environmental Engineering, 2012, 19(3): 138-142. doi: 10.3969/j.issn.1671-1556.2012.03.034 常丹, 刘建坤, 李旭, 等. 冻融循环对青藏粉砂土力学性质影响的试验研究[J]. 岩石力学与工程学报, 2014, 33(7): 1496-1502.CHANG Dan, LIU Jiankun, LI Xu, et al. Experiment study of effects of freezing-thawing cycles on mechanical properties of Qinghai−Tibet silty sand[J]. Chinese Journal of Rock Mechanics and Engineering, 2014, 33(7): 1496-1502. 卜建清,王天亮. 冻融及细粒含量对粗粒土力学性质影响的试验研究[J]. 岩土工程学报,2015,37(4): 608-614. doi: 10.11779/CJGE201504005BU Jianqing, WANG Tianliang. Influences of freeze-thaw and fines content on mechanical properties of coarse-grained soil[J]. Chinese Journal of Geotechnical Engineering, 2015, 37(4): 608-614. doi: 10.11779/CJGE201504005 BEIER N A, SEGO D C. Cyclic freeze-thaw to enhance the stability of coal tailings[J]. Cold Regions Science & Technology, 2009, 55(3): 278-285. PROSKIN S, SEGO D, ALOSTAZ M. Oil sands MFT properties and freeze-thaw effects[J]. Journal of Cold Regions Engineering, 2012, 26(2): 29-54. doi: 10.1061/(ASCE)CR.1943-5495.0000034 艾凯明,周科平,胡建华,等. 寒区尾矿力学特性的环境响应试验[J]. 矿冶工程,2004,34(3): 4-8.AI Kaiming, ZHOU Keping, HU Jianhua, et al. Experiment on environmental response of tailings’ mechanical properties in cold regions[J]. Mining and Meatallurgical Engineering, 2004, 34(3): 4-8. 潘宝峰,王琰,张铁志. 无机结合料稳定铁尾矿砂冻融特性的研究[J]. 低温建筑技术,2010,32(1): 8-10. doi: 10.3969/j.issn.1001-6864.2010.01.003PAN Baofeng, WANG Yan, ZHANG Tiezhi. Research on freezing-thawing characteristics of inorganic binders stabilized iron tailings[J]. Low Temperature Architecture Technology, 2010, 32(1): 8-10. doi: 10.3969/j.issn.1001-6864.2010.01.003 南京水利科学研究院. 土工试验规程: SL237—1999[S]. 北京: 中国水利水电出版社, 1999. 肖小文, 阳军生, 王树英, 等. 第三系粉质黏土地层隧道围岩大变形分析及控制研究[J]. 铁道学报, 2015, 37(10): 110-116.XIAO Xiaowen, YANG Junsheng, WANG Shuying, et al. Mechanism analysis and control of large deformation of tunnel excavated in the tertiary silty clay deposit[J]. Journal of the China Railway Society, 2015, 37(10): 110-116. 王永忠, 艾传井, 刘雄军. 冻融作用对南方粉质黏土物理力学性质的影响[J]. 地质科技情报, 2010, 29(5): 107-111.WANG Yongzhong, AI Chuanjing, LIU Xiongjun. Physical and mechanical properties changes of silty clay in Southern China due to freeze-thaw action[J]. Geological Science and Technology Information, 2010, 29(5): 107-111. LEE W, BOHRA N C, ALTSCHAEFFL A G, et al. Resilient modulus of cohesive soils and the effect of freeze-thaw[J]. Canadian Geotechnical Journal, 1995, 32(4): 559-568. doi: 10.1139/t95-059 -
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