改良粉土在高速公路路基中的适用性研究

Research on the applicability of improved silt in highway subgrade

为扩大粉土在高速公路路基中的应用,对粉土分别采用水泥、石灰和含有黏粒的粉质土进行改良。结合高速公路路基填料的要求,从改良粉土的击实特性、压缩模量、加州承载比和渗透性方面分析了其在高速公路路基工程中的适用性。研究表明,在粉土中掺入石灰、水泥均能提升粉土的压缩模量和CBR值,且相同条件下,水泥相比石灰的提升作用更显著,对承载力较低的粉土、变形要求较高的路基,可优先采用水泥改良粉土;掺入含有黏粒的粉质土因掺入黏粒少而使粉土的压缩模量和CBR值降低,不满足高速公路路基填料的要求;在粉土中掺入石灰可降低粉土的渗透性,石灰改良土可优先用于路基需要隔水、封水的部位和雨水较多地区的路基工程。根据上述研究结果,对粉土作为填料的高速公路路基设计给出了建议。

In order to expand the application of silt in highway subgrade,cement,lime and silty soil with clay were used to improve the silt.Combined with the requirements of subgrade filling for expressway,the applicability of improved silt in expressway subgrade engineering was analyzed in terms of compaction characteristics,compression modulus,California bearing ratio and permeability.The research shows that the compression modulus and CBR value of silt can be improved by adding lime and cement into silt,and under the same conditions,cement has more significant lifting effect than lime.For silt with lower bearing capacity and subgrade with higher deformation requirements,cement can be preferred to improve silt.The compression modulus and CBR value of the original silt are decreased because of less clay after being mixed with silty soil containing clay,which doesn’t meet the requirements of subgrade filling of expressway.The permeability of silt can be reduced by adding lime into the silt.Lime improved soil can be used in subgrade works where water separation and sealing are needed and where there is much rain.According to the research results,some suggestions are given for the design of highway subgrade with silt as filler.