酸碱及可溶盐溶液对桂林红黏土压缩性影响实验研究

Experimental study of compressibility of red clay affected by acid-base and soluble salt solutions

为探讨水环境对红黏土工程地质性质的影响,以桂林岩溶地区典型地段的红黏土为研究对象,对浸泡于不同浓度的HCl、NaOH、Fe(NO3)3和Al(NO3)3溶液中的试样进行固结实验。结果显示:(1)在HCl和NaOH溶液中浸泡后,红黏土的压缩模量都降低,压缩系数都增大,且溶液浓度越大其值降低或增大的幅度越大;(2)浸泡在NaOH溶液中的红黏土的压缩模量比浸泡在HCl溶液中的大,且压缩模量值随着溶液浓度的增加而减小,压缩系数则相反;(3)在Fe(NO3)3和Al(NO3)3溶液中浸泡后,红黏土的压缩模量会随着溶液浓度的增大而增大,压缩系数随着溶液浓度的增大而降低,且Fe(NO3)3溶液对红黏土的压缩性影响作用比Al(NO3)3溶液的大。

Guilin is located in the southwest of NE-SW trend Xiang-Gui lowland corridor with coordinates of longitude 110＆#176;17′and latitude 25＆#176;14′.It has a subtropical monsoon climate with abundant annual rainfall,and is hot,humid and rainy.Guilin is in the Lijiang River valley plain,which has well-developed karst and large areas of red clay.The engineering properties of red clay in Guilin are very complex,making the water stabili-ty poor.The chemical activity is closely related with the chemical composition of groundwater.To study the effects of the water environment on engineering geological properties,the red clay was taken from a typical karst area in Guilin.The samples were soaked in different concentration solutions of HCl,NaOH,Fe （NO3 ）3 and Al（NO3 ）3 .Experimental results showed that：（1）The compression modulus of the red clay de-creased and the compression coefficient increased when it was soaked in different concentration of HCl and NaOH solution,and that the greater the solution concentration was,the larger the decrease in range would be;（2）The compression modulus of the red clay was greater when the red clay was soaked in a solution of NaOH than that soaked in a solution of HCl,and the compression modulus value decreased with the increase of solution concentration,the opposite of the compression coefficient;（3）The compression modulus of the red clay increased and the compression coefficient decreased with the increase of solution concentration when the red clay was soaked in solutions of Fe（NO3 ）3 and Al（NO3 ）3 ,and the effect of the Fe（NO3 ）3 solution was greater than that of the Al（NO3 ）3 solution.