摘要
以南水北调中线工程南阳膨胀土为研究对象,在保持含水率20%和干密度1.7g/cm^3不变的条件下,基于磷尾矿最佳掺量为7.5%,分别将EPS颗粒、聚丙烯纤维按不同比例掺入膨胀土中进行无荷膨胀率、无侧限抗压强度和三轴CU试验。试验结果表明:EPS颗粒能有效抑制膨胀土的膨胀性,但会降低膨胀土的强度和延性,当掺量不为0%时,复合改良土应力应变曲线均随围压的增加,由应变软化型向应变硬化型过渡,15%为最佳掺量。进一步分析发现黏聚力和内摩擦角与掺量均呈线性负相关,并得到与掺量有关的抗剪强度公式。聚丙烯纤维对复合改良土抗压强度峰值影响较小,但能提高其延性和残余强度,使土体由脆性破坏转变为塑性破坏。最终得到磷尾矿、EPS颗粒和聚丙烯纤维最佳掺量分别为7.5%、15%、0.4%。
The expansive soil in the middle route of South-to-North Water Diversion Project in Nanyang was taken as the research object.Under the condition of keeping moisture content and dry density unchanged at 20%and 1.7 g/cm^3,respectively,based on the 7.5%optimum dosage of phosphate tailings,we mixed EPS particles and polypropylene fibers in different proportions and added them into the expansive soil for tests of unloaded swelling ratio,unconfined compressive strength,and triaxial CU.The results showed that EPS particles can effectively restrain the expansion and shrinkage of expansive soil,but will reduce the strength and ductility of the expansive soil.With the increase of confining pressure,the stress-strain curves of the modified soils with more than 0%dosage will all increase and change from strain softening type to strain hardening type,with 15%as the best dosage.Further analysis showed that the cohesion and internal friction angle are both linearly negatively correlated with the dosage.A formula of shear strength related to dosage was obtained.Polypropylene fiber has smaller effects on the peak compressive strength of the composite modified soil,but it can increase the ductility and residual strength of the latter,so that the soil can be transformed from brittle failure to plastic failure.After comprehensive analysis,we found the optimum dosages of phosphorus tailings,EPS particles and polypropylene fibers to be 7.5%,15%,and 0.4%,respectively.
作者
庄心善
王康
王俊翔
李凯
ZHUANG Xinshan;WANG Kang;WANG Junxiang;LI Kai(College of Civil Architecture and Environment,Hubei University of Technology,Wuhan 430068,China)
出处
《南水北调与水利科技》
CSCD
北大核心
2018年第6期164-170,共7页
South-to-North Water Transfers and Water Science & Technology
基金
国家自然科学基金(41772332)~~
关键词
膨胀土
磷尾矿
EPS
聚丙烯纤维
抗剪强度
expansive soil
phosphorous tailings
EPS
polypropylene fiber
shear strength
