摘要
在已有氧化镁碳化固化软弱土试验研究的基础上,通过整体碳化固化技术进行了淤泥质土的室内模型试验。采用常宜高速公路现场河塘淤泥质土进行活性氧化镁的整体碳化试验,并对碳化处理土的温度、含水率和pH值进行测试,以分析氧化镁处理土的碳化反应程度;通过微型贯入试验和压缩试验以评价碳化固化土的承载力和压缩特性。结果表明,当淤泥质软土的初始含水率为35%时,MgO碳化后能取得良好的处理效果,土的状态由软塑全部变为硬塑,由微型贯入试验换算所得的允许承载力可达300 k Pa以上;当初始含水率为46%时,二氧化碳的运移距离受到限制,整体碳化程度降低,承载力提高并不显著,仅达到可塑状态,而只有在通气孔附近以及土体表面等有限区域能得到有效加固;碳化法处理对淤泥土的压缩性有显著改善:即使只进行简单压实,也可以通过氧化镁碳化法使处理后土的压缩性降低。与其他淤泥质土处理方法对比,在施工要求低、排水不便的条件下可通过添加减水剂、细砂等辅助措施增大淤泥质土的透气性,使氧化镁碳化法处理淤泥土取得更好的处理效果。
Based on the existing studies of the MgO-carbonated soft soils,model tests of mucky soils are conducted through the carbonation stabilization technology. The mucky soil taken from Chang-Yi highway(from Yixing to Changzhou) is used for the reactive Mg O-mass carbonation and stabilization experiments. Some parameters including temperature,moisture content and pH are measured to analyze the degree of carbonization. Laboratory micro penetration test(MPT) and compression tests are conducted to evaluate the bearing capacity and compressibility of carbonated mucky soil. The results indicate that(1) the mucky soil can achieve the better treatment effect after MgO carbonation when its initial moisture content is 35%,its state is hard plastic state transformed from its soft plastic state,and its bearing capacity reaches 300 kPa.(2) When the initial water content of mucky soil is 46%,the migration distance of carbon dioxide is restricted,resulting in that its carbonization degree and bearing capacity improvement are limited and the soil state is still the plastic state except that the limited areas near the surface and vents can be effectively improved.(3) Carbonation can obviously reduce compression of mucky soil even only through simple compaction measures. Comparing with other treatment methods of mucky soil,it is considered that the air permeability of mucky soil can be increased by some auxiliary measures,e.g.,adding water reducer or fine sand under the conditions of low construction requirements and inconvenient drainage,the better treatment effect may be obtained by magnesium oxide carbonation method.
作者
秦川
刘松玉
杜广印
蔡光华
QIN Chuan;LIU Songyu;DU Guangyin;CAI Guanghua(Institute of Geotechnical Engineering,Southeast University,Nanjing 210096;School of Civil Engineering,Nanjing Forestry University,Nanjing 210037)
出处
《工程地质学报》
CSCD
北大核心
2019年第6期1302-1310,共9页
Journal of Engineering Geology
基金
国家自然科学基金项目(51279032,41330641)
江苏省交通厅科技项目(2018T01)资助~~
关键词
活性氧化镁
碳化
淤泥质土
承载力
压缩性
Reactive magnesia
Carbonation
Mucky soil
Bearing capacity
Compression