微生物拌和渗滤砂土固化试验研究

Experimental study on solidification of microorganism-mixing-improved percolating sand

河道崩岸现象频发,严重威胁河流航运和两岸人民的生命安全。微生物矿化技术作为一种新型的土体改良技术,在河道护岸方面具有一定的应用前景。本文选用3种不同颗粒粒径范围的砂土进行微生物拌和渗滤固化,并基于无侧限抗压强度试验、碳酸钙含量、崩解率及吸水率测试,分析颗粒粒径、渗滤次数及拌和配比对微生物固化效果的影响,探究拌和法和渗滤法结合的固化机制。研究结果表明:拌和法在砂土试样中生成的碳酸钙大多起填充作用,胶结程度较低,而后续渗滤固化能够显著改善土体特性。拌和配比为2:8、粒径为0.3~0.6 mm时试样的固化效果较好,抗压强度最高可达1.86 MPa;试样的碳酸钙含量和抗压强度随渗滤次数增加呈非线性增长,而强度上限随粒径增大呈上升趋势。试验得出崩解率最低为2%,吸水率最低降至9.26%,较一般黏性土而言,固化试样抵抗水的侵蚀性较强且具有一定的渗水性,在河道护岸及施工工艺方面具有一定应用价值。

Microbially induced calcite precipitation method,a new soil improvement technology,has a good application prospect in river bank revetment.This study chooses three different particle size ranges of sandy soil for microbial mixture-improved infiltration curing,and conducts unconfined compression tests along with the tests of calcium carbonate content,breakdown rate,and water absorption.Then,we analyse the effects of particle size,infiltration times,and mixing ratio on the curing effect,and investigate the curing mechanism of the mixing method combined with the percolation method.Results show that most of the calcium carbonate generated in the mixing stage plays a pore-filling role and the resulting degree of cementation is low,while the subsequent infiltration and solidification improve soil properties significantly.With a mixing ratio of 2:8 and a particle size range of 0.3-0.6 mm,the samples manifest a better curing effect and their compressive strength is increased up to 1.86 MPa.Their calcium carbonate content and compressive strength are increased nonlinearly with the increase in filtration times,while the upper limit of strength increased with particle size.The test results reveal that the lowest disintegration rate is 2%and the lowest water absorption rate is 9.26%.Compared with typical clay soils,the solidified samples have stronger water erosion resistance and certain permeability,indicating a certain application value for river bank protection and construction technology.