高速公路宕碴路堤超深软基的真空联合堆载预压加固

Improvement of super deep and soft ground under embankment of expressway with combination method of vacuum and preloading

某高速公路路堤由抗变形能力极差的宕碴料填筑 ,填高大于 6m;地基主要由厚 2 0 m左右、含水量为 43 %～ 70 %的淤泥质土组成。为了解决高速公路主要的土工问题——路堤的稳定与沉降 ,工程采用了真空联合堆载预压法加固高填方宕碴路堤的超深软弱土地基。结果表明加固效果相当明显 ,与堆载预压法相比 ,采用真空联合堆载预压法工期节省一半 ,路基沉降量却减少 1 0 % ;地基土强度平均增长 2倍以上 ;实际填高 6.7m的路基在填筑完成抽真空结束再预压 2个月后地基土固结度大于 95 %。路堤填筑期的地基土侧向挤出日均位移量小于 1 .0 mm/d,路堤与地基一直处于稳定状态。预测的路基工后沉降小于 2 0 cm。

The embankment of an expressway is constructed by material whose anti deformation ability is very bad, and its fill height is larger than 6 m. The ground contains a muddy clay with thickness of 20 m and water content of 43%~70%. For the stability and settlement of embankment, combination method of vacuum and preloading is adaped to improve the foundation. It is indicated that the improvement effect is very obvious. Compared with preloading, the period of construction can be decrease halfly, the settlement of roadbed reduced 10%. The strength of soil is increased by more than 2 times. The consolidation degree of soil is larger than 95% after the embankment of height of 6.7 m is filled and vacuum preloading is constructed for 2 months. The displacement of foundation soil is smaller than 1.0 mm/d during the construction of embankment, and the embankment and ground soil is stable. The settlement of roadbed is smaller than 20 cm during the operation. The experience can be referenced to the other and similar engineerings.