灌注桩绿色泥浆制备及泥皮的渗透特性

泥浆在地基处理、泥水盾构等工程中起重要角色，增稠剂是泥浆质量的关键所在。传统泥浆使用的增稠剂主要为羧甲基纤维素钠(CMC)，这种泥浆降解难度大，很容易污染环境。针对以上问题，采用瓜尔胶和黄原胶来取代传统泥浆添加剂进行绿色泥浆配置。通过配比实验和改进滤失实验研究泥浆的最优配比以及其新型泥皮的渗透特性。结果表明：瓜尔胶：黄原胶最优配比为1：5。通过增加试验压力，可以减小泥皮孔隙比，从而有效降低泥皮的渗透系数。CMC和新型添加剂对泥浆改性效果大致相同，在膨润土添加2.5g瓜尔胶与0.5g黄原胶得到的泥皮渗透系数比同质量分数纯膨润土泥浆小3个数量级。新型天然添加剂对泥浆的改性效果较好，添加高分子材料会使形成的泥皮厚度变小。试验和理论分析结果证明了新型绿色泥浆在桩基工程应用的可行性，可推广应用。

Study on the preparation of green mud skin and the permeability characteristics of mud skin for grouted piles

Mud plays an important role in foundation treatment, mud-water shield and other projects, and the thickener is the key to the quality of mud. The thickening agent used in traditional mud is mainly sodium carboxymethyl cellulose (CMC), which is difficult to degrade and easily pollutes the environment. To address the above problems, guar gum and xanthan gum were used to replace the traditional mud additives for green mud configuration. The optimal ratio of the mud and the permeability characteristics of its new mud skin were studied through proportioning experiments and improved filtration loss experiments. The results show that the optimal ratio of guar gum to xanthan gum is 1:5, and the permeability coefficient of the mud skin can be effectively reduced by increasing the test pressure.The effect of CMC and the new additives on the mud modification is roughly the same, and the permeability coefficient of the mud skin obtained with the addition of 2.5g of guar gum to the bentonite clay and 0.5g of xanthan gum is three orders of magnitude smaller than that of the same quality fraction of the pure bentonite clay slurry. The modification effect of the new natural additives on the mud is better, and the addition of polymer materials will make the thickness of the mud skin formed smaller. The results of the test and theoretical analysis proved the feasibility of the new green mud in the application of pile foundation engineering, which can be widely used.