玄武岩残积土环剪试验研究

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。

Ring-shear Test of Basalt Residual Soil

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.