高铁路堤中改性膨胀土工程应用特性试验研究

Experimental study on application characteristics of improved expansive soil in high-speed railway embankment

用南宁高铁建设中常遇到的弱性膨胀土及水泥改性膨胀土作路堤填料,填筑1:1高铁路堤模型,依托自行设计的监测系统,对自然降雨蒸发条件下路堤内的含水率、温度、吸力与土压力4种特征参数的变化规律以及沉降变形量进行监测。研究结果表明:膨胀土路堤边坡大气急剧影响深度集中在0.5 m内,最大影响深度可达2~3 m;最大工后沉降量膨胀土路堤面约为5.7 mm,水泥改良土仅约2.5 mm,水泥改良膨胀土可用作高铁路堤建设填料;路堤边坡坡面侧向变形以收缩变形为主,呈现"上部大,下部小"的特点,相同位置处,膨胀土断面变形量大于改良土断面。

A high speed railway embankment model equaling to prototype was built by using weak expansive soil and cement-treated expansive soil, which were taken from the high-speed railway construction in Nanning. Under natural rainfall and evaporation conditions, based on the self-designed monitoring system, the changing regularities of moisture content, temperature, suction and soil pressure in the embankment as well as the settlement deformation were monitored. The experiment results indicated： Expansive soil embankment slope atmosphere influence depth sharply concentrated within 0.5 m, the maximum influence depth could reach 2-3 m; the maximum settlement impact depth of the expansive soil embankment surface was about 4.5 mm, while the cement-treated soil was only about 2.5 mm, thus, cement-treated expansive soil can be used as a kind of high-railway embankment filling material. Furthermore, the lateral deformation of embankment slope was mainly shrinkage deformation, showing the characteristics of large on upper part and small in the lower part; and in the same position, the deformation of the expansive soil section was larger than that of the improved soil section.