襄荆高速公路软弱地基高路堤填筑控制试验研究

Experimental study on control of high embankment construction on soft foundation in Xiang-jing Expressway

软弱地基路堤填筑高度一般小于 5 m,需时较长而影响工期,襄荆高速公路软弱地基路堤填筑高达 8 m,加快施工进度与保证施工安全成为一大技术难题,为此进行了一系列的试验研究。现场详勘和试验表明该软弱地基存在 1～1.5 m 厚的硬壳层及下卧砂卵石层且原状土十字板剪切强度较高(Su= 44 kPa),有利于加快填土速率;选取了塑料排水板及砂垫层加土工格栅的软弱地基处理方案;基于排水条件得到了较大改善,经试验,证明适当降低规范要求的沉降控制标准是可行的。据此,根据监测数据进行动态调整后,填土速率得到了较大提高,施工安全也得到了保证;路堤填筑到设计高度后,通过堆载预压试验,对工后沉降预测值进行了验证,取得了良好的效果。

The construction of 8-meter high embankment on soft foundation in Xiang-jing Expressway in Hubei Province, about 3 meters higher than general one, had the technical difficulty to hasten progress and ensure embankment constructing quality and safety, thus a series of field researches such as kinds of field tests, deformation controlling standards test, preloading treatment test, etc, was done. Firstly, field exploring and tests revealed the existence of 1.0-1.5m-thickness dry crust, sand and gravel strata, and relatively higher strength of vane shear test, which is benefit for accelerating speed of embankment constructing; Secondly, a disposal scheme is selected with combination of prefabricated strip, sand cushion and geogrid; a looser deformation controlling standard which can lead to higher speed of constructing, was successfully tested based on improving condition of drainage in soft foundation; Thirdly, a preloading treatment test was carried out to verify the reliability of prediction of settlement after construction.