粉土改良膨胀土的路用性能与现场试验  

Road performance and field test of expansive soil improved by silt

作　　者：张艺 李永强 章定文[1] 侯爵[3] 樊晓军 唐紫琼 ZHANG Yi;LI Yong-qiang;ZHANG Ding-wen;HOU Jue;FAN Xiao-jun;TANG Zi-qiong(School of Transportation,Southeast University,Nanjing,Jiangsu 211189,China;No.Three Engineering Co.,Ltd.of CCCC First Highway Engineering Co.,Ltd.,Beijing 100000,China;Transportation Engineering Construction Bureau of Jiangsu Province,Nanjing,Jiangsu 210017,China)

机构地区：[1]东南大学交通学院,江苏南京211189 [2]中交一公局第三工程有限公司,北京100000 [3]江苏省交通工程建设局,江苏南京210017

出　　处：《岩土力学》2023年第10期2942-2952,共11页Rock and Soil Mechanics

摘　　要：为探究粉土对膨胀土的改良效果,对不同粉土占比改良膨胀土进行了胀缩特性、路用性能和微观结构测试。研究表明:掺入粉土改变了膨胀土土体颗粒成分及结构,抑制了膨胀土的胀缩潜势;随着粉土颗粒的增加,膨胀土的密实度和无侧限抗压强度均先增大后减小,最大干密度在粉土占比为40%时达到1.889 g/cm^(3),无侧限抗压强度在粉土占比为10%时最大,加州承载比(CBR)值持续显著提高,回弹模量呈下降趋势,均满足规范要求;验证了粉土改良膨胀土的可行性,确定了最佳配合比为粉土掺量40%。为便于现场施工,并考虑现场拌和均匀程度,先掺入3%低剂量石灰对膨胀土进行“砂化”,降低膨胀土黏性使其破碎。在此基础上,采用粉土掺量40%对膨胀土进行改良后用于高速公路路堤填筑,并开展了现场压实度、CBR值、弯沉值等测试。现场试验结果表明:现场填筑联合改良试验段和单一石灰改良对照段整体压实质量良好,但试验段压实度易受粉土均匀程度影响而降低;试验段路基CBR值和路基弯沉与对照段相当,粉土改良有效弥补了相对于对照段减少的2%石灰所提供的强度。To explore the improvement effect of adding silt on expansive soil,the swelling-shrinkage characteristics,road performance and microstructure of expansive soil with different proportions of silt were tested.The results show that the incorporation of silt changes the composition and structure of soil particles,and inhibits the expansion and contraction potential of expansive soil.With the increase of silt particles,the compactness and unconfined compressive strength of expansive soil increase first and then decrease.The maximum dry density reaches 1.889 g/cm^(3)when the proportion of silt is 40%,and the unconfined compressive strength reaches the maximum when the proportion of silt is 10%.The California bearing ratio(CBR)value continues to increase significantly,and the rebound modulus shows a downward trend.All of these indexes meet the requirements of the specification.The feasibility of using silt to improve expansive soil is verified,and the optimum dosing ratio of silt is determined to be 40%.In order to facilitate onsite construction and consider the uniformity of onsite mixing,3%low-dosage lime is first added to causes the performance of expansive soil to tend towards those of sandy soil so as to reduce the viscosity of the expansive soil and break it.On this basis,the expansive soil is applied to highway embankment filling after improved with 40%silt content,and onsite compaction degree,CBR value,deflection and other tests are carried out.The field test results show that the overall compaction quality of the experimental section improved by silt and lime and the control section treated by the single lime are controlled well,but the compaction degree of the test section is reduced due to the influence of the uniformity of the silt.The CBR value and subgrade deflection of the test section are comparable to those of the control section,and the silt improvement effectively compensates for the strength provided by the 2%lime reduced relative to the control section.

关 键 词：膨胀土 粉土 改良 胀缩特性 路用性能 

分 类 号：TU443[建筑科学—岩土工程]