风积沙压实特性试验研究

风积沙是一种特殊的筑路材料,其压实特性是影响沙漠公路施工质量的重要因素。为了研究风积沙的压实特性,进行了筛分试验、标准重型击实试验和振动试验及野外现场试验。筛分试验结果表明:风积沙级配不良,沙粒均匀,粒径主要分布在0.25～0.074 mm之间,属于细砂;击实曲线与常规工程材料显著不同,呈一个特殊的横写S型,干密度随含水率变化有两个峰值,揭示了风积沙在含水率为0和最佳含水率下,均可以达到最佳密实度的特有性质。振动试验表明:风积沙的最佳振动频率为45～50 Hz。现场试验进行机械优化配置,采用干压实工艺,试验压实度代表值达到了96%,效果良好。沙样的电镜扫描图显示,振动干压实后,风积沙微观结构良好,达到了预期的效果。

Experimental research on compaction characteristics of aeolian sand

Unlike the other road materials, aeolian sand had some compaction characteristics that were key factors of influence on construction qualities of highway in the desert. In order to study the characteristics, a series of laboratory and field tests were performed, which included the experiments of sieve analysis, modified standard compaction, vibrating compaction and field test. By analyzing the sieve analysis test data. it was found that the gradation of aeolian sand was bad, with even fine grains with diameters mostly ranged from 0.25mm to 0.074mm. Then, based on the laboratory compaction test results, a compaction curve was plotted, which was quite different to the other kinds of road materials, and similar to a horizontally-written letter S. There were two peak values in the special curve with the increase of water content, which was the special character of aeolian sand could be well compacted whatever it was dry or wet. Also, according to the laboratory vibrating test results, the best vibrating frequency range was proposed, which was from 45 to 50 Hertz. Moreover, some field compaction tests were carried out. On the construction site of highway, the aeolian sand subgrade was compacted in the condition of natural water content, with optimized construction machines, obtain an acceptable degree of compaction, 96%, meeting the current specifications. At last, comparative studies were carried out with electron microscope pictures of aeolian sand, which indicated that the microstructure of compacted dry aeolian sand was much denser than that of natural one.