复合型固化剂加固黄土物理力学特性试验研究

Experimental Study on Physical and Mechanical Properties of Loess Reinforced byCompound Curing Agent

为研究复合型固化剂对兰州黄土的加固效果,通过一系列物理力学特性试验和微观结构分析,对不同配合比的复合型固化剂加固黄土的击实特性、无侧限抗压强度、抗剪强度参数、破坏模式和微观结构展开研究。结果表明:复合型固化剂可显著改善黄土的击实特性和水敏性,增大无侧限抗压强度和抗剪强度参数,0.2 L/m^(3)F1+3%水泥是复合型固化剂加固黄土的最佳配合比;与天然黄土相比,最佳配合比的复合型固化剂加固黄土的无侧限抗压强度、内摩擦角和黏聚力分别增大了633.26%、19.41%和421.18%,无侧限条件和围压为200 kPa时,试样的破坏应变分别减小了15.79%和25.00%,破坏应力分别增大了633.84%和127.66%;复合型固化剂通过F1离子交换作用和水泥水化反应,改变了粒间接触和排列方式,显著减小黄土中小孔隙和孔隙度,促进土颗粒团聚,提高密实度和强度。与天然黄土相比,最佳配合比的复合型固化剂加固黄土后孔隙度减小了5.91%。

In order to study the reinforcement effect of compound curing agent on loess in Lanzhou,the compaction characteristics,unconfined compressive strength,shear strength parameters,failure mode and microstructure of compound curing agent were studied through a series of physical and mechanical characteristic tests and microstructure analysis.The test results show that the composite curing agent can significantly improve the compaction characteristics and water sensitivity of loess,and increase the unconfined compressive strength and shear strength parameters.0.2 L/m^(3)F1+3%cement is the best mixture ratio of composite curing agent to strengthen loess.Compared with the natural loess,the unconfined compressive strength,internal friction angle and cohesion of the loess reinforced with the optimum mixture of compound curing agent increased by 633.26%,19.41%and 421.18%,respectively.When the unconfined condition and confining pressure were 200 kPa,the failure strain of the specimen decreased by 15.79%and 25.00%,respectively.The failure stress increases 633.84%and 127.66%respectively.By means of F1 ion exchange and cement hydration reaction,the compound curing agent can change the contact and arrangement mode between grains,significantly reduce the small and medium pores and porosity of loess,promote the agglomeration of soil particles,and improve the compactness and strength.Compared with the natural loess,the porosity of the loess strengthened by the best combination of curing agent decreased by 5.91%.