Residual strength of loess-gravel interface under snowmelt in Ili valley, Xinjiang
-
摘要: 为研究融雪作用下黄土-卵砾石接触面残余强度,以新疆伊犁谷地某黄土-卵砾石接触面滑坡为例,通过自制模具,制作黄土-卵砾石接触面环剪试样,开展不同含水率黄土-卵砾石接触面环剪试验,并通过扫描电镜(SEM),从微观结构角度探究水对黄土-卵砾石接触面残余强度的影响。试验结果表明:黄土-卵砾石接触面抗剪强度随着含水率的增加而减小,剪切过程中存在应变软化现象,随着正应力及含水量的增加,应变软化现象越不明显;黄土-卵砾石接触面残余强度随着法向应力的增大而增大,且存在较好的线性关系,符合摩尔库伦强度准则;黄土-卵砾石接触面残余强度参数随着含水率的增加而降低,以含水率w=18%为界(塑限含水率19.1%附近),当含水率为10%~18%时,残余内摩擦角φr变化较小(Δφr=5.4°),当含水率为18%~26%时,残余内摩擦角φr变化较大(Δφr=9.0°);微观结构方面,随着含水率的增加,黄土-卵砾石接触面形成软化"泥膜",部分填充了卵砾石凹凸部分,剪切面较为光滑,在剪切过程中,黏粒更加分散,附着在黄土颗粒表面,部分填充孔隙,起润滑作用,降低了残余强度。本文的研究成果可以为新疆伊犁谷地黄土-卵砾石接触面型滑坡形成机理研究及工程防治提供科学参考。Abstract: In order to study the residual strength of the loess-gravel interface, this paper investigated the residual strength of the loess-gravel interface with different water content by improved ring shear tests, what's more, the scanning electron microscopy (SEM) was taken to study the microstructure of the loess-gravel interface.The results show that residual strength of the loess- gravel interface decreased with increasing of the water content, and strain softening occurred during tests.With the increase of normal stress and water content, the strain softening phenomenon became less obvious; The residual strength of the loess-gravel interface increased with the normal stress, and there was a good linear relationship, which met the Mohr-Coulomb strength criterion, The residual strength parameters of the loess-gravel interface decreased with water content increasing.There was a critical water content w=18% (near the plastic limit water content 19.1%), when the water content ranged from 10%-18%, the residual friction angle φr changed slightly (Δφr=5.4 °).Respectively, when the water content ranged from 18%-26%, the residual friction angle φr changed greatly (Δφr=9.0 °).In terms of microstructure, with the water content increasing, the soft "mud film" was formed on the loess-gravel interface and partially filled with uneven surface.Thus the shearing surface was smooth.Meanwhile, during the shearing process, the clay was dispersed and absorbed to the surface of the loess particles and partially filled the pores which lubricated the loess particles and reduced the residual strength.The research results of this paper could provide scientific reference for the formation mechanism and engineering protection of loess-gravel interface landslide in Ili Valley.
-
Key words:
- Ili Valley /
- loess-gravel interface /
- residual strength /
- ring shear test /
- SEM
-
表 1 伊犁黄土基本物理指标
Table 1. Physical indices of the Ili loess
相对密度Gs 干密度ρd/(g·cm-3) 天然含水率wB/% 液限含水率LL/% 塑限含水率PL/% 塑性指数PI 2.64 1.59~1.63 14.1 28.2 19.1 9.15 表 2 伊犁黄土矿物成分
Table 2. Mineral composition contents of the Ili loess
矿物 石英 伊利石 钠长石 绿泥石 方解石 wB/% 37.77 28.80 12.03 11.53 9.87 表 3 不同含水率试验应变软化系数
Table 3. Strain softening coefficient of different samples of water content
含水率/% 正应力/kPa 应变软化系数IB 10 100 0.24 200 0.23 300 0.15 400 0.12 14 100 0.19 200 0.18 300 0.12 400 0.11 18 100 0.16 200 0.12 300 0.10 400 0.08 22 100 0.12 200 0.08 300 0.05 400 0.03 26 100 0.05 200 0.04 300 0.02 400 0.02 表 4 不同含水率试样残余强度参数
Table 4. Residual strength parameters of different water content samples
含水率/% 残余内摩擦角φr/(°) 残余黏聚力cr/kPa 10 32.9 30.5 14 29.6 28.7 18 27.5 27.0 22 23.4 26.7 26 18.5 25.4 -
[1] 刘小丽, 邓建辉, 李广涛.滑带土强度特性研究现状[J].岩土力学, 2004, 25(11):1849-1854. http://www.cqvip.com/Main/Detail.aspx?id=10867719 [2] Sassa K, Hiroshi F, Gonghui W, et al.Undrained dynamic-loading ring-shear apparatus and its application to landslide dynamics[J].Landslides, 2004, 1(1):7-19. doi: 10.1007/s10346-003-0004-y [3] 汪发武.高速滑坡形成机制:土粒子破碎导致超孔隙水压力的产生[J].长春科技大学学报, 2001, 31(1):64-69. [4] 蒋树, 王义锋, 唐川, 等.基于环剪试验的复活型低速滑坡活动机理[J].地质科技情报, 2019, 38(2):256-261. http://www.cqvip.com/QK/93477A/20192/68907581504849574850485148.html [5] 王炜, 骆亚生.剪切方式对重塑黄土残余强度的影响[J].水土保持通报, 2018, 38(6):177-181. [6] 张昆, 郭菊彬.滑带土残余强度参数试验研究[J].铁道工程学报, 2007, 13(8):13-15. http://d.wanfangdata.com.cn/Periodical/tdgcxb200708004 [7] 汤罗圣, 殷坤龙, 刘艺梁, 等.万州区典型堆积层滑坡滑带土抗剪强度参数间关系研究[J].地质科技情报, 2013, 32(6):191-195. [8] Skempton A W.Residual strength of clays in landslides, folded strata and the laboratory[J].Géotechnique, 1985, 35(1):3-18. doi: 10.1680/geot.1985.35.1.3 [9] Bromhead E N, Dixon D.The field residual strength of London clay and its correlation with loboratory measurements, especially ring shear tests[J].Géotechnique, 1986, 36(3):449-452. doi: 10.1680/geot.1986.36.3.449 [10] Tiwari B, Brandon T L, Marui H.Comparison of residual shear strengths from back analysis and ring shear tests on undisturbed and remolded specimens[J].Journal of Geotechnical and Geoenvironmental Engineering, 2005, 131(9):1071-1079. doi: 10.1061/(ASCE)1090-0241(2005)131:9(1071) [11] Vithana S B, Shinya N, Sho K, et al.Effects of overconsolidation ratios on the shear strength of remoulded slip surface soils in ring shear[J].Engineering Geology, 2012, 131/132:29-36. doi: 10.1016/j.enggeo.2012.01.015 [12] Gibo S, Egashira K, Ohtsubo M.Residual strength of smectite-dominated soils from the Kamenose landslide in Japan[J].Canadian Geotechnical Journal, 1987, 24(3):456-462. doi: 10.1139/t87-057 [13] 洪勇, 岳玉秋, 郑孝玉, 等.大连滨海粉质黏土剪切力学特性环剪试验[J].吉林大学学报:地球科学版, 2016, 46(5):1475-1481. http://d.wanfangdata.com.cn/Periodical/cckjdxxb201605019 [14] 李文可.泾阳南塬黄土环剪强度特性试验研究[J].水利与建筑工程学报, 2016, 14(1):184-187. [15] 王顺, 项伟, 崔德山, 等.不同环剪方式下滑带土残余强度试验研究[J].岩土力学, 2012, 33(10):2967-2972. [16] 黄宏翔, 陈育民, 王建平, 等.钙质砂抗剪强度特性的环剪试验[J].岩土力学, 2018, 39(6):2082-2088. http://www.cnki.com.cn/Article/CJFDTotal-YTLX201806021.htm [17] 丁红丽, 骆亚生.环剪试验条件下不同地区黄土的残余强度研究[J].地下空间与工程学报, 2017, 13(6):1511-1516. [18] 张荣, 吴益平, 李小伟, 等.不同含水率下滑带土抗剪强度特性研究[J].科学技术与工程, 2015, 15(15):195-199. http://d.wanfangdata.com.cn/Periodical/kxjsygc201515036 [19] Ma C, Zhan H, Zhang T, et al.Investigation on shear behavior of soft interlayers by ring shear tests[J].Engineering Geology, 2019, 254:34-42. doi: 10.1016/j.enggeo.2019.04.002 [20] 洪勇, 周蓉, 郑孝玉, 等.不同排水条件下砂-黄土界面的剪切力学特性[J].吉林大学学报:地球科学版, 2019, 49(4):1073-1081. http://www.cnki.com.cn/Article/CJFDTotal-CCDZ201904014.htm [21] 朱俊高, Shakir R R, 杨有莲, 等.土-混凝土接触面特性环剪单剪试验比较研究[J].岩土力学, 2011, 32(3):692-696. http://d.wanfangdata.com.cn/Periodical/ytlx201103009 [22] 王晓明, 买振军.新疆伊犁典型特大型黄土滑坡群成因机制及变形特征[J].水利与建筑工程学报, 2016, 14(4):195-200. http://d.wanfangdata.com.cn/Periodical/fsjs201604038 [23] 南京水利科学研究院.SL237-1999土工试验规程[S].北京: 中国水利水电出版社, 1999. [24] 柴寿喜, 韩文峰, 王沛, 等.用冻干法制备微结构测试用土样的试验研究[J].煤田地质与勘探, 2005, 33(2):46-48. [25] Bishop A W.Progressive failure-with special reference to the mechanism causing it[Z].:, 1967. [26] 卢肇钧, 张惠明, 陈建华, 等.非饱和土的抗剪强度与膨胀压力[J].岩土工程学报, 1992, 14(3):1-8. http://www.cqvip.com/Main/Detail.aspx?id=918283 [27] 陈传胜, 张建敏, 文仕知.基于有效垂直应力水平的滑带土强度参数适用性研究[J].岩石力学与工程学报, 2011, 30(8):1705-1711. http://www.cnki.com.cn/Article/CJFDTotal-YSLX201108025.htm [28] 王炜.重塑黄土残余强度的环剪试验研究[D].陕西杨凌: 西北农林科技大学, 2014. [29] 张浪, 雷学文, 孟庆山, 等.玄武岩残积土环剪试验研究[J].长江科学院院报, 2019, 36(4):93-97. http://www.cnki.com.cn/Article/CJFDTotal-CJKB201904021.htm [30] 王腾飞, 李远耀, 曹颖, 等.降雨型浅层土质滑坡非饱和土-水作用特征试验研究[J].地质科技情报, 2019, 38(6):181-188. [31] 段钊, 彭建兵, 冷艳秋.泾阳南塬Q_2黄土物理力学特性[J].长安大学学报:自然科学版, 2016, 36(5):60-66. [32] 王炜, 骆亚生.重塑黄土抗剪强度的环剪试验研究[J].水土保持通报, 2017, 37(5):110-113. [33] 谢辉辉, 刘清秉, 胡桂阳.基于环剪试验的滑带土抗剪强度特性研究[J].人民长江.2018, 49(11):108-113. [34] 邓华锋, 原先凡, 李建林, 等.土石混合体直剪试验的破坏特征及抗剪强度取值方法研究[J].岩石力学与工程学报, 2013, 32(S2):4065-4072. -