Dispersive soil is easy to be lost when it is in contact with water, and it is easy to cause engineering disasters. For its dispersibility, lime, fly ash and other materials are often used to modify it, but the traditional soil solidifying materials are easy to pollute the environment. The influence of enzyme-induced karst calcium bicarbonate solution (enzyme-induced CFPK) on dispersibility of the modified chemically dispersive soil was investigated through mud ball disintegration test, pinhole test, mud column water erosion test and triaxial test. The results show that the dispersion of soil can be effectively inhibited by enzymatic CFPK. With the increase of liquid-solid ratio of CFPK, the shear strength of CFPK modified soil increased as a whole, which mainly showed that the cohesion of soil increased. The partial stress of the dispersive soil and the modified soil with the enzyme CFPK increased or tended to be gentle with the increase of axial strain, showing a strain hardening type. Duncan-zhang hyperbola model was used to fit the soil, and the fitting correlation was greater than 0.95, indicating a good fitting effect. It can be seen that enzymatic CFPK can effectively modify dispersive soil and improve its shear strength.
HUO Jiang-ru, FAN Heng-hui, ZHANG Zhuo, PANG Shuai, ZHANG Shuo, WANG Peng-wei.
Experiment on Mechanical Modification of Chemically Dispersed Soil by Enzyme-simulated Karst Calcium Bicarbonate Solution[J].
Science Technology and Engineering, 2026, 26(2): 735-744 DOI:10.12404/j.issn.1671-1815.2408899
樊恒辉等[14]基于溶洞钟乳石的形成机理提出一种仿岩溶碳酸氢钙(calcium bicarbonate from pseudo-karstification,CFPK)加固技术。邱维钊等[15]和蔡东廷等[16]分别研究了CFPK改良膨胀土、风积沙,发现CFPK通过填充和胶结作用对膨胀土和风积沙具有良好的改性与加固作用。高策等[17]研究了CFPK改性分散土,发现CFPK可改善土体分散性,但是对于CFPK改性分散土的力学性质没有做深入的研究。
(1)酶促CFPK改性化学性分散土分散性试验。液固比的定义为酶促CFPK的质量与干土质量的比值[17],判别其分散性设置4∶1、5∶1、6∶1、7∶1、8∶1共5种配比。针孔试验按照美国试验与材料协会(American Society for Testing and Material,ASTM)提出的D4647-20[24]标准进行,泥球崩解试验和泥柱水蚀试验按照标准[25-26]进行。
分散土和不同酶促CFPK含量试样放大2 000倍的扫描电镜(scanning electron microscope, SEM)图片如图12所示,可以看出,分散土黏土颗粒较为松散且细小孔隙分布较多,主要为块状与碎屑状,土颗粒间以点对点连接。添加了酶促CFPK后,土样的颗粒形态、孔隙分布和表面结构特征发生了明显的变化,生成的碳酸钙晶体附着在土颗粒表面,土颗粒间的接触面积显著增大,由松散土颗粒的点对点接触转变为碳酸钙晶体面对面接触,生成的碳酸钙胶结土壤颗粒,填充孔隙,使得土壤结构变得更加致密。
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