摘要
针对上海某桩基施工现场产生的工程废弃泥浆,将传统的固化剂生石灰作为添加药剂,在静置沉降阶段测试了不同添加量时浑液面沉降随时间的变化;对于静置沉降后不同添加量的泥浆絮体进行了真空预压试验,研究了真空预压过程中的排水量变化特性及试验结束后模型箱内的颗粒分布特性,采用MIP试验研究了真空预压前、后不同位置处孔隙的分布变化规律;基于SEM试验解释了生石灰在废浆处理中的水化作用。研究结果表明:(1)加入生石灰不仅能加快静置沉降阶段浑液面的沉降速率,而且由于生石灰水化物结晶体能将土颗粒联接起来,形成体积较大、结构松散、可以起到骨架作用的土团粒,后期的增渗作用十分明显;(2)在0.2%、0.5%、0.8%生石灰的3种添加量中,掺量为0.5%时,静置沉降和真空预压阶段泥面沉降速度均为最快;(3)经药剂真空预压法处理后,废浆中的孔隙孔径由处理前的3 184~11 308 nm为主减小至681~3 244 nm为主,孔隙总量减小约60%~79%。
To improve the waste slurry discarded from a pile foundation project in Shanghai, the curing agent（calcium lime） is used as an additive material. The deformation on the waste slurry surface with various additives is measured during settlement at rest. The vacuum preloading tests are conducted for the slurry flocculation. The variation in water discharge during vacuum preloading and the particle distribution in the slurry flocculation at various locations as the tests completed are then investigated. The changes in the size distributions of the pores in the waste slurry are also explored using MIP tests before and after the vacuum preloading tests. The hydration mechanism of the calcium lime on the improvement of waste slurry is illustrated using the scanning electron microscope image processing. It shows that the settlement rate on the waste slurry surface accelerated after adding calcium lime, and soil particles are joined together by lime hydrate crystals to form the skeletonized soil-flocculation aggregates with larger volume, looser structure, and enhanced permeability. Among the calcium lime contents of 0.2%, 0.5% and 0.8%, the surface settlement of the waste slurry with the content of 0.5% is fastest both during the settlement at rest and in the vacuum preloading test. Most of the pore sizes of waste slurry decrease from between 3,184 to 11,308 nm before improvement to between 681 to 3,244 nm after vacuum preloading with flocculation, indicating that the total pore volume decreased by 60% to 79%.
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2017年第12期3453-3461,共9页
Rock and Soil Mechanics
基金
国家自然科学基金(No.41772303)
上海市自然科学基金(No.17ZR1410100)~~
关键词
药剂真空预压法
废弃泥浆
生石灰
增渗作用
扫描电镜
压汞试验
vacuum preloading with flocculation
construction waste slurry
calcium lime
enhanced permeability effect
scanningelectron microscope
mercury intrusion test
