水泥/石灰和土壤固化剂复合改良膨胀土试验研究

Experimental Study on Composite Improvement of Expansive Soil by Cement/Lime and Soil Solidifying Agent

采用水泥/石灰和BJ-W土壤固化剂对安徽地区膨胀土进行了改良试验研究。依据液限、塑限和自由膨胀率试验初步选定改良膨胀土的配合比范围,并通过胀缩总率、无侧限抗压强度和稳定性试验,进一步分析了改良膨胀土的性能变化规律。试验结果表明,掺入水泥/石灰和BJ-W土壤固化剂复合改良中、弱膨胀土时,液限逐渐减小,塑限逐渐增大,自由膨胀率降低到40%以下,且胀缩总率低于0.7%;无侧限抗压强度和稳定性试验中,改良膨胀土的强度和水稳系数(>80%)显著增加,且经过5次干湿循环后,改良膨胀土的强度衰减率小于20%,膨胀土的反复胀缩特性显著改善。综合考虑改良膨胀土的胀缩和强度特性,采用水泥和BJ-W土壤固化剂复合改良膨胀土效果最佳,中膨胀土最优配合比为7%水泥和0.02%BJ-W土壤固化剂,弱膨胀土最优配合比为6%水泥和0.02%BJ-W土壤固化剂。

The expansive soil was improved by cement/lime and BJ-W soil stabilizer in Anhui Province.According to the liquid limit,plastic limit and free expansion rate test,the mix ratio range of the improved expansive soil was preliminarily selected.The performance change law was further analyzed by the total expansion and contraction rate,unconfined compressive strength and stability test.The test results show that when the cement/lime and BJ-W soil stabilizer were mixed to improve the medium and weak expansive soil,the liquid limit decreased gradually,the plastic limit increased gradually,the free expansion rate decreased to below 40%,and the total expansion and contraction rate was less than 0.7%;In the unconfined compressive strength and stability test,the strength and water stability coefficient(>80%)of the improved expansive soil increased significantly.After 5 dry-wet cycles,the strength attenuation rate was less than 20%,and the repeated expansion and contraction characteristics were significantly improved.Considering the expansion-shrinkage and strength characteristics,the effect of composite improvement by cement and BJ-W soil stabilizer is the best.The optimal mix ratio of medium expansive soil is 7%cement and 0.02%BJ-W soil stabilizer.The one of weak expansive soil is 6%cement and 0.02%BJ-W soil stabilizer.