酸性环境下Q_(2)黄土压缩特性试验研究

Experimental Study on Compression Characteristics of Q_(2) Loess in Acidic Environment

针对酸性污染土物理力学性质恶化的现象,采用室内人工模拟受酸液污染土样的方法,开展土常规试验、压缩试验探究Q2黄土在酸液浸泡时间和酸液浓度双因素作用下,试样孔隙比、含水率等基本物理及压缩系数、压缩模量等指标和压缩e—p曲线的变化规律,以及水-酸耦合作用对黄土压缩性的影响规律。结果表明:浸泡时间一定时,随酸液浓度增大,含水率、孔隙比、压缩系数在逐渐增大,压缩模量在减小。浸泡12 d时,酸液浓度0.1 mol/L增加至3 mol/L,压缩系数a1-2由0.355 MPa-1增大到1.275 MPa-1,压缩模量Es1-2由5.580 MPa减小至1.855 MPa;酸液浓度一定时,随浸泡时间延长,含水率、孔隙比、压缩系数在逐渐增大,压缩模量在减小。酸液浓度3 mol/L时,浸泡时间从1 d至12 d,压缩系数a1-2由0.308 MPa-1增大到1.275 MPa-1,压缩模量Es1-2由6.301 MPa减小至1.855MPa;水-酸耦合作用提高了黄土压缩性,且在充分浸泡条件下,酸液对黄土压缩性的影响远大于水的影响。研究结果可为酸蚀黄土区工程建设提供相关参考。

In view of the deterioration of physical and mechanical properties of soil due to acidic pollution,laboratory routine and compression tests have been conducted on artificial acid samples of Q2 loess soil to investigate double factors of acid soaking time and acid concentration on the void ratio,moisture content and other basic physical parameters,as well as the variation of compression coefficient,compression modulus and the compression curve of e-p.Meanwhile,the water-acid coupling effect on the compressibility of loess is studied.The results show that under the same acid soaking time,the moisture content,void ratio,and compression coefficient gradually increased with the increase of acid concentration,while the compressibility modulus reduced.After soaking for 12 days,the acid concentration increased from 0.1 mol/L to 3 mol/L,and the compression coefficient a1-2 increased from 0.355 MPa-1 to 1.275 MPa-1,accompanied with the decrease of compression modulus Es1-2 from5.580 MPa to 1.855 MPa.When the acid concentration is constant,with the extension of soaking time,the moisture content,void ratio and compression coefficient increased gradually,and the compression modulus decreased.At the acid concentration of 3 mol/L,with the increase of the soaking time from 1 d to 12 d,the compression coefficient a1-2 increased from 0.308 MPa-1 to 1.275 MPa-1,and the compression modulus Es1-2 decreased from 6.301 MPa to 1.855 MPa.The coupling effect of water and acid improves the loess compressibility,and the effect of acid solution on the loess compressibility is much greater than that of water under the condition of full immersion.The results can be used as a reference for construction activities in acid etched loess areas.