湘南红黏土公路路基压实度标准研究

Study on Compaction Degree Criterion of Red Clay Highway Subgrade in Southern Hunan

为了探究湘南红黏土公路路基压实标准降低的依据和具体幅度,对红黏土开展了一系列室内土工试验,分析了压实度、含水率对红黏土物理力学特性的影响,获取了渗透率、压实系数、CBR等指标与压实度的关系曲线,最终根据上述指标随压实度的变化规律给出了压实度降低的建议值。研究表明:压实度对红黏土收缩性和膨胀性的影响较小,随着压实度的提高,红黏土的渗透系数和压缩系数均明显降低,而内摩擦角和黏聚力则逐渐增加,但黏聚力在压实度由93%增加到96%过程中没有明显变化,当初始含水率控制在30%左右,压实度大于93%时,红黏土的CBR值均符合规范要求。综合各指标的变化规律,建议湘南地区红黏土路基的压实度可总体降低至93%,且填筑时的含水率应略大于最优含水率。

In order to research the basis and the specific range of lowering southern Hunan red clay highway subgrade＇ s compaction degree,a series of indoor soil mechanic tests on the red clay is carried out. The influence of compaction degree and water content on red clay ＇ s physical and mechanical properties is analyzed. The curves of the indicators（ permeability coefficient,compression coefficient,CBR,etc.）varying with compaction degree are acquired. Based on these trends,the suggested value of lowering compaction degree is proposed at last. The result shows that（ 1） compaction degree has little influence on red clay＇ s swelling and shrinkage;（ 2） with the increase of compaction degree,permeability coefficient and compression coefficient decrease significantly,while internal friction angle and cohesion rise gradually,but cohesion does not change obviously when compaction degree increases from 93% to 96%;（ 3） when compaction degree is more than 93% and initial water content retains nearly 30%,CBR value is within the demanded range of specification. In conclusion,it is suggested that the compaction degree of southern Hunan red clay subgrade can be reduced to 93%,and the water content should be slightly higher than the optimum water content when filling the subgrade.