铅污染土固化体冻融循环效应和微观机制  

Effect of freeze-thaw cycle on engineering properties and microstructure of stabilized/solidified lead contaminated soil treated by cement

作　　者：李江山[1] 王平[1] 张亭亭[1] 李振泽[1] 薛强[1] LI Jiang-shan WANG Ping ZHANG Ting-ting LI Zhen-ze XUE Qiang(State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhen 430071)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071

出　　处：《岩土工程学报》2016年第11期2043-2050,共8页Chinese Journal of Geotechnical Engineering

基　　金：国家自然科学基金项目(41602315;51479194);中国科学院学科交叉与合作创新团队项目(Y426011C01);武汉市高新技术成果转化及产业化项目(2013060803010403);岩土力学与工程国家重点实验室课题(Z015003)

摘　　要：为了研究冻融循环对铅污染土固化体工程特性的影响规律及其作用机制,开展了不同压实度试样(90%,96%)的冻融循环试验。通过对经历不同冻融循环次数(0,3,6,10次)作用后的试样进行无侧限抗压强度、渗透和溶出特性试验,探讨了冻融循环作用对铅污染土固化体工程特性的影响规律。试验结果表明,冻融循环作用对不同压实度试样有着不同的影响规律。随着冻融循环次数增加,90%压实度试样的抗压强度降低、渗透性增大、铅浸出浓度增大,而96%试样呈现出相反的规律,即冻融循环对高压实度试样影响不大。为了探索冻融循环作用对铅污染土固化体工程特性影响的微观机制,开展了不同冻融循环作用下试样微观结构试验。试验结果表明,冻融循环对高压实度(96%)试样微观结构影响不大,随着时间的延长,试样内颗粒团聚,孔隙减小,试样内孔隙以颗粒间和团粒内孔隙为主;而冻融循环作用使低压实度试样(90%)孔隙增大,试样内颗粒团聚,团粒间大孔隙占主要比重,这是导致低压实度铅污染土固化体工程特性的劣化的根本原因。Freeze-thaw cycle tests are conducted to investigate the engineering properties and mechanisms of cementstabilized/solidified（S/S） lead-contaminated soils with different compaction degrees（90% and 96%）. After different freeze-thaw cycles（0, 3, 6 and 10 times）, the unconfined compressive strength tests, penetration tests and leaching tests are conducted on samples to investigate the effect of freeze-thaw cycles on engineering properties of S/S samples. The results showed that the freeze-thaw effect depends on the compaction degrees of samples. For the samples with compaction degree of 90%, the permeability and Pb leaching concentration increase with the freeze-thaw cycles, while the unconfined compressive strength decreases. However, little variation is observed for the samples with compaction degree of 96% as the freeze-thaw cycle increases. Scanning electron microscope（SEM） and mercury intrusion porosity（MIP） tests are also conducted to study the micro-mechanism. The results show that the freeze-thaw cycles pose little influence on the microstructure of S/S samples with compaction degree of 96%. Soil particles aggregate and porosity decreases with the freeze-thaw cycles. The inter-particular pores and intra-aggregate pores occupy a fairly large proportion. However, the freeze-thaw cycles enlarge the pore of samples with compaction degree of 90%, and the inter-aggregate pores take large proportion, which is the reason that the engineering properties of S/S samples with low compaction degree is weakened during the freeze-thaw cycles.

关 键 词：铅污染土 固化/稳定化 冻融循环 微观机制 

分 类 号：TU43[建筑科学—岩土工程]