泡沫泥浆在防渗墙泥浆护壁中的应用

Application of Foam Mud in the Construction of Cut-off Wall

在土体粒径大、渗透性能好的地层中开挖防渗墙或打桩时经常会出现槽(孔)壁坍塌、泥浆渗漏量大和卡钻等问题。而利用泡沫密度小、黏度大的特性,在护壁泥浆中加入泡沫有助于防渗堵漏,具有较好的应用效果。阐述了为寻求泡沫泥浆的合理配比、探讨其护壁效果,选择α-烯基磺酸钠(AOS)、脂肪醇聚氧乙烯醚硫酸钠(AES)、十二烷基硫酸钠(K12)和复合植物蛋白发泡剂(HT)等4种发泡剂进行的发泡体积、半衰期测定并开展了泡沫泥浆基本性质试验和渗透试验,结果表明:4种发泡剂中,HT泡沫半衰期为500 min,保持稳定的时间最长,在泥浆中加入泡沫后可以提高泥浆的黏度,降低泥浆的动切力和静切力,使泥浆黏滞阻力减小并可减少环空能量损失;相同条件下,泡沫泥浆比普通泥浆渗漏量小,其渗漏量随着泡沫掺比的增加先减小、后增大,泡沫掺比为20%时渗漏量最小。

When excavating cut-off wall or driving pile in strata with large soil particle size and good permeability,problems such as trough(hole)wall collapse,large mud leakage and stuck drilling are common.Due to the characteristics of low density and high viscosity of foam,adding foam to wall protection mud is helpful to prevent seepage and reduce leakage,which has a good application prospect.Therefore four kinds of foams such as a-alkenyl sulfonate(AOS),sodium polyoxyethylene ether sulfate(AES),sodium dodecyl sulfate(K12)and complex vegetable protein foaming agent(HT)were selected to test the foaming volume and half-life,and the basic properties of foam mud and foam mud penetration test were carried out.The results showed that the half-life of HT foam was 500min,and whose stable time was the longest;Foam can greatly improve the viscosity of mud,reduce the dynamic shear force and static shear force of mud,which can reduce the mud viscosity resistance and the annular energy loss.Under the same conditions,the leakage of foam mud is smaller than that of ordinary mud,and the leakage increases first and then decreases with the proportion of foam.When the proportion of foam is 20%,the permeability is the minimum.