吉舒高速公路过湿土路基生石灰处治技术研究

发布时间：2018-04-18 19:14

本文选题：季冻区 + 过湿土　；参考：《吉林建筑大学》2017年硕士论文

【摘要】：本文依托《过湿土公路地基处理技术研究》科技项目,针对吉舒高速公路实际工程应用技术,开展了过湿土路基生石灰处治技术的研究,取得如下成果:1.石灰处治土的液塑限随着石灰掺入比的增大而增加,而塑性指数的变化规律正好相反。土中掺入石灰后,土颗粒比重呈逐渐增长趋势,其颗粒粒径大小发生了明显变化。随着石灰掺量的增加,土中粉粒与粘粒的含量均呈减小的趋势,但粘粒的变化更加明显。2.随着石灰掺量的增加,石灰处治土的最佳含水率呈逐渐增大的趋势,而最大干密度呈现逐渐减小的趋势。石灰处治土的抗剪强度随着石灰掺量以及压实度的增大呈现出比较明显的增长趋势。3.在路基路面力学结构体系中,构建了过湿土路基顶面石灰处治土加强层结构,通过分析加强层对土基强度、土基顶面压应力分布、土基内动力偏应力以及路面结构力学响应的影响规律得出:土基加强层的厚度与模量,对土基强度提高作用显著,但在土基强度较差的情况下,一味地增加加强层的厚度或模量,并不能很好的改善土基的强度。铺筑加强层的过湿土路基,其顶面压应力减小,压应力分布更加平缓。随着加强层厚度及模量的增加,土基表面压力应力与土基内动力偏应力均呈现逐渐减小的趋势,同时路面基层与底基层底部弯拉应力与弯拉应变逐渐减小,且厚度与模量越大,其减小的幅度越大。终上所述,增加生石灰处治过湿土加强层厚度与模量有利于延长路面结构使用寿命。4.随着石灰掺量的增加,石灰处治土的高度与体积冻胀率呈现减小而逐渐趋于稳定的趋势,石灰的掺入能够有效提高路基的整体抗冻性。经若干次冻融循环作用后,石灰处治土的强度虽有所衰减,但仍远大于素土强度;无论是素土还是石灰处治土,随着压实度的增大,其冻融前后的强度均有所增加,说明提高土基的压实度,是保证路基整体强度与稳定性的最经济、最有效的措施之一。提高路基的压实度,亦可以改善冻融后土基的CBR值,从而确保冻融后路基的承载能力。考虑经济方面的因素,研究认为石灰掺入比控制在3~5%比较理想。5.从吉舒高速公路路基水温状况监测数据可以看出,路基内部的温度随着大气温度的变化而变化。且深度愈大,其变化幅度愈小,即路基内部温度受大气温度影响愈小。通过比较日温差变化可以发现,5%生石灰处治路基内部日温差变化幅度小于换填山皮石路基,说明石灰处治土路基具有更好的保温性能,其路基最大冻结深度小。另外,同一埋置深度下,5%生石灰处治路基体积含水量变化幅度小于换填山皮石路基,说明其具有一定的隔水性能。研究表明,在吉舒高速公路,采用生石灰处治过湿土修筑路基在技术上是可行的。
[Abstract]:In this paper, based on the project of "Research on Foundation treatment Technology of overwet soil Highway", aiming at the practical engineering application technology of Jishu Expressway, the research on the treatment technology of quicklime for overwet soil subgrade has been carried out, and the following results have been obtained: 1.The liquid-plastic limit of lime treated soil increases with the increase of lime ratio, but the change of plasticity index is just the opposite.When lime was added into the soil, the specific gravity of soil particles increased gradually, and the particle size changed obviously.With the increase of lime content, the content of silt and clay in soil decreased, but the change of clay was more obvious.With the increase of lime content, the optimum moisture content of lime treated soil increases gradually, while the maximum dry density decreases gradually.The shear strength of lime treated soil shows an obvious increasing trend with the increase of lime content and compaction degree.In the mechanical structure system of roadbed and pavement, the structure of lime treating soil strengthened layer on top of overwet soil subgrade is constructed. The strength of strengthening layer to soil foundation and the distribution of compressive stress on top surface of soil foundation are analyzed.The influence of dynamic deflection stress in soil foundation and the mechanical response of pavement structure shows that the thickness and modulus of strengthening layer of soil foundation have a significant effect on improving the strength of soil foundation, but when the strength of soil foundation is poor,Only increasing the thickness or modulus of the strengthening layer can not improve the strength of soil foundation.The compressive stress of overwetted soil subgrade is reduced and the distribution of compressive stress is more gentle.With the increase of the thickness and modulus of the strengthening layer, the surface pressure stress of the soil foundation and the dynamic deflection stress of the soil foundation gradually decrease, and the bending tension stress and the bending tension strain at the bottom of the pavement base and the bottom of the base gradually decrease, and the thickness and modulus increase.The greater the extent of the decrease.In the end, increasing the thickness and modulus of the strengthening layer of quicklime treatment of overwetted soil is beneficial to prolong the service life of pavement structure .4.With the increase of lime content, the frost heave ratio of lime treated soil decreases and tends to be stable gradually. Lime mixing can effectively improve the overall frost resistance of roadbed.After several freeze-thaw cycles, the strength of lime treated soil decreases, but it is still much larger than that of plain soil, and the strength of lime treated soil increases with the increase of compaction degree.It shows that increasing the compaction degree of soil foundation is one of the most economical and effective measures to ensure the overall strength and stability of subgrade.Increasing the compaction degree of roadbed can also improve the CBR value of soil foundation after freeze-thaw, so as to ensure the bearing capacity of roadbed after freeze-thaw.Considering the economic factors, it is considered that the lime blending ratio should be controlled at 3 ~ 5%.From the monitoring data of subgrade water temperature in Jishu Expressway, it can be seen that the temperature inside the subgrade changes with the change of atmospheric temperature.The greater the depth, the smaller the variation, that is, the temperature inside the roadbed is less affected by atmospheric temperature.By comparing the daily temperature difference, it can be found that the range of daily temperature difference within the subgrade treated with 5% quicklime is smaller than that of replacing the embankment with rock filling, which indicates that the lime treatment of soil subgrade has better thermal insulation performance, and the maximum freezing depth of the roadbed is small.In addition, the change range of volume water content of subgrade treated with 5% quicklime at the same buried depth is smaller than that of replacement embankment, which indicates that it has certain water insulation performance.The research shows that it is technically feasible to use quicklime to construct roadbed on Jishu Expressway.
【学位授予单位】：吉林建筑大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U416.1

【相似文献】