腐殖酸对污泥固化土长期强度的劣化效应

Degradation Effect of Humic Acid on Long-term Strength of Solidified Sludge Soil

研究腐殖酸对污泥固化土长期强度的影响具有重要意义。对有机质含量较低的污泥分别添加0.5%,1.5%,3%,4.5%,6%的腐殖酸,基于水泥、偏高岭土、石灰等固化剂进行固化,得到标准养护状态下240 d污泥固化土的抗弯强度、应力-应变关系及破坏应变的发展规律。研究结果表明:在外加腐殖酸和污泥固有有机质缓释腐殖酸的协同作用下,固化土初期抗弯强度急剧增加,随后有不同程度的降低;腐殖酸添加量从0.5%到6%,各龄期固化土抗弯强度几乎都有一定程度劣化,固化作用和腐殖酸侵蚀作用平衡点由180 d提前到60 d;高含量腐殖酸固化土的破坏模式呈"塑性→脆性→偏塑性"变化规律,腐殖酸含量越大,塑性破坏作用越明显。

Studies on the effect of humic ac id on th e long-term strength of solidified sludge soil , a re of great impor-tance. In this research , sludge with low organic m a t te r co n ten t was solidified by mixtures of cemen t , m e ta /a o l in , and lime , etc. On this bas is , humic ac id in proportion of 0.5% , 1.5% , 3% an d 4.5% , 6% , respe ctively , was added into the sludge. The development laws of b en d in g strength , s tre s s -s tra in rela tio n sh ip an d failure strain of so-lidified sludge soil under standa rd cu r in g condi tion for 240 days were o b ta in e d. R e su lts rev e aled th a t 1） u n d e r thejoint actions of humic acid and in h e re n t humic a c id slowly re le a sed from organic matters of th e sludge , th e in it ialbending strength of solidified soil in c re a se d rap id ly an d th en d e c re a s ed to different e x te n ts; 2） when humic ac id content increased from 0.5% to 6% , th e b en d in g s trength of solidified soil a t d ifferent ages almost d eg rad ed to a certain degree , and the ba lance between solidification an d humic a c id erosion o ccu r red in ad v an c e , from th e 180 th day to the 60th day; 3 ） the failure mode of solidified soil with high co n ten t of humic a c id ex p e r ien c ed th e ten d en cy from plastic failure to br i t t le fa ilu re , an d th en to p a r t ia l p la s t ic fa ilu re , an d th e b igge rmore obvious the action of p la s t ic fa i lu re i s.