海水环境下硫酸盐侵蚀钙质砂注浆体试验研究

Experimental study on sulfate erosion of calcareous sand grouting in seawater environment

为研究硫酸根离子侵蚀效应对钙质砂吹填岛礁注浆加固钙质砂地基服役性能的影响,采用耦合温度和离子浓度的加速侵蚀方法,基于海水侵蚀试验装置开展不同水泥类型、侵蚀时间、水灰比条件下硫酸根离子对于注浆结石体性能的弱化试验。获得海水中硫酸根离子对注浆结石体力学性能及渗透性能的影响规律,并对侵蚀后的注浆结石体进行微观测试,揭示硫酸根离子对钙质砂注浆结石体的侵蚀弱化机理。试验结果表明,硫酸根离子渗透注浆结石体内部与水化反应产物发生反应生成石膏以及钙矾石等产物引发注浆结石体发生侵蚀破坏,而动水环境会加剧硫酸根离子对注浆结石体的侵蚀弱化效应,动水侵蚀组结石体在侵蚀时间为3.28 a时,抗压强度为5.41 MPa,较淡水对照组降低23.9%;渗透系数为7.159×10^(-5)cm/s,较淡水对照组增大6.691×10^(-5)cm/s。

In order to study the effect of sulfate ion erosion on the service performance of calcareous sand foundation reinforced by grouting on the islands and reefs,the accelerated erosion method of coupling temperature and ion concentration was adopted.Through the simulation of seawater flow characteristics test device,the weakening test of sulfate ions on grouting stone body under different cement types,erosion time and water-cement ratio was carried out.The influence of sulfate ions in seawater on the mechanical properties and permeability of grouting stone body was studied,and the microscopic test of grouting stone body after erosion was carried out,so as to obtain the erosion and weakening mechanism of sulfate ions in seawater on calcareous sand grouting stone body.The test results showed that sulfate ions penetrated into grouting stone bodies and reacted with hydration products to form gypsum and ettringite,which leads to erosion and destruction of grouting stone bodies.The dynamic water environment aggravated the erosion weakening of sulfate ions on grouting stone bodies.The compressive strength of the stone body in the hydrodynamic erosion group was 5.41 MPa and the permeability coefficient was 7.159x10^(-5) cm/s when the erosion time was 3.28 years,which was 23.9%lower and 6.691×10^(-5) cm/s higher than that in the fresh water erosion group.