玄武岩残积土环剪试验研究
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摘要
为准确了解土体大剪切位移下的力学特性,利用环剪仪对不同剪切方式、剪切速率下玄武岩残积土的峰值强度与残余强度进行研究,找到适合玄武岩残积土的剪切方式和剪切速率,并在此基础上分析干密度与含水率对峰值强度和残余强度的影响。试验结果表明:已经形成剪切面的试样,能很快达到残余强度状态,预剪与多级剪所得试验结果偏大,应选用单级剪;剪切速率对峰值强度影响较大,而对残余强度影响相对较小,剪切速率大的试样出现"漏水"与"挤土"现象,容易对结果造成偏差;随着干密度的增大,峰值强度增大,残余强度先减小后不变;含水率越大,峰值强度和残余强度越小,玄武岩残积土存在明显的遇水软化现象。研究结果可为玄武岩残积土坡的稳定性分析与灾害防治提供参考。
To accurately understand the mechanical properties of soil with large shear displacement, we examined the peak strength and residual strength of basalt residual soil under different shear modes and shear rates using ring shear apparatus to obtain the shear mode and the shear rate suitable for basalt residual soil, and on this basis analyzed the impacts of dry density and moisture content on peak strength and residual strength. Results unveil that specimens with existing shearing surface could reach residual strength state rapidly. As the results of pre-shear and multistage shear are large, we should select single-stage shear. Shear rate has a great influence on peak strength, but the influence on the residual strength is relatively small. Specimens under large shear rate would experience water leakage and soil squeezing, which is liable to cause deviation to the result. Moreover, with the increase of dry density, peak strength increases, while residual strength decreases first and then remains unchanged. The greater the water content, the smaller the peak strength and residual strength. Residual soil of basalt softens obviously when contacting with water. The research results offer reference for the stability analysis and treatment of basalt residual soil slope.
To accurately understand the mechanical properties of soil with large shear displacement, we examined the peak strength and residual strength of basalt residual soil under different shear modes and shear rates using ring shear apparatus to obtain the shear mode and the shear rate suitable for basalt residual soil, and on this basis analyzed the impacts of dry density and moisture content on peak strength and residual strength. Results unveil that specimens with existing shearing surface could reach residual strength state rapidly. As the results of pre-shear and multistage shear are large, we should select single-stage shear. Shear rate has a great influence on peak strength, but the influence on the residual strength is relatively small. Specimens under large shear rate would experience water leakage and soil squeezing, which is liable to cause deviation to the result. Moreover, with the increase of dry density, peak strength increases, while residual strength decreases first and then remains unchanged. The greater the water content, the smaller the peak strength and residual strength. Residual soil of basalt softens obviously when contacting with water. The research results offer reference for the stability analysis and treatment of basalt residual soil slope.
引文
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[15] SKEMPTON A V. Long-term Stability of Clay Slopes[J]. Geotechnique, 1974, 14(2):77-101.
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[17] 张俊峰,王协群,邹维列,等.土-格栅界面强度参数和剪切刚度试验研究[J]. 长江科学院院报,2014,31(3):77-83.
[2] MATHONEY J,COFFIN M. Large Igneous Provinces:Continenta1,Oceanic, and Planetary Flood Volcanism[M]. Washington D C: American Geophysical Union, 1997.
[3] 戴福初,王思敬,李焯芬.香港大屿山残坡积土的残余强度试验研究[J]. 工程地质学报,1998,6(3):223-229.
[4] SKEMPTON A V.Residual Strength of Clays in Landslides,Folded Strata and the Laboratory[J].Geotechnique,1985, 35(1):3-18.
[5] 丁树云, 毕庆涛, 蔡正银,等.环剪仪的试验方法研究[J]. 岩土工程学报,2013,35(增2):197-201.
[6] 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.
[7] 胡显明.不同剪切速率下碎石土滑坡滑带土残余强度特性研究[D].武汉:中国地质大学,2012.
[8] 孙涛,洪勇,栾茂田,等.采用环剪仪对超固结黏土抗剪强度特性的研究[J]. 岩土力学,2009,30(7):2000-2004.
[9] 尹占巧,许成顺,刘海强, 等. 环剪仪在超固结土残余强度分析中的应用[J]. 防灾减灾工程学报,2013,33(5):556-560.
[10] 温明星,骆亚生,刘紫韦,等.掺粉煤灰压实黄土环剪试验研究[J]. 长江科学院院报,2016,33(3):70-74.
[11] 许成顺,王馨,杜修力,等. 不同黏性土的残余强度及其抗剪强度指标特性研究[J]. 岩土工程学报,2017,39(3):436-443.
[12] STARKT D,CHOI H,MCCONE S.Drained Shear Strength Parameters for Analysis of Landslides[J]. Journal of Geotechnical and Geoenvironmental Engineering, 2005, 131(5): 575-588.
[13] BISHOP A W, GREEN G E, GARGA V K, et al. A New Ring-shear Apparatus and Its Application to the Measurement of Residual Strength[J]. Geotechnique, 1971, 21(4):273-328.
[14] 吴迪,简文彬,徐超. 残积土抗剪强度的环剪试验研究[J]. 岩土力学,2011,32(7):2045-2050.
[15] SKEMPTON A V. Long-term Stability of Clay Slopes[J]. Geotechnique, 1974, 14(2):77-101.
[16] 张明,胡瑞林,殷跃平,等.滑坡型泥石流转化机制环剪试验研究[J].岩石力学与工程学报,2010,29(4):822-832.
[17] 张俊峰,王协群,邹维列,等.土-格栅界面强度参数和剪切刚度试验研究[J]. 长江科学院院报,2014,31(3):77-83.