煤矸石换填膨胀土路基的沉降研究

Replacing Expansive Soil with Coal Gangue in Subgrade Settlement

针对广西合山市八二路膨胀土路基,考虑采用其附近溯河矿区内煤矸石对膨胀土进行换填。通过对溯河矿区煤矸石及八二路膨胀土进行现场试验及室内实验,研究了其物理力学性质,采用数值模拟技术,探讨了煤矸石换填比例对不同含水率的膨胀土路基路面沉降的影响,取得了以下研究成果:合山地区膨胀土力学性质受其含水率的影响较大,需对膨胀土进行换填;合山市煤矸石散体级配良好,易于压实,适合用作路基填充材料;膨胀土路基在荷载作用下,路面沉降曲线整体上呈对称形式,中间部位相对于两边沉降量更大,对于半路堑路基断面形式,距道路中线同样距离的位置,路面靠近下部边坡的一侧沉降量更大;随着换填比例的增加,路面最大沉降量和差异沉降量明显减小,根据模拟结果建议将合山市八二路膨胀土路基换填3.5m厚的煤矸石。

Aiming at expansive soil subgrade of Road 82, Heshan City, Guangxi, we considered using the near Suhe mining area coal gangue to replace the expansive soil. Through field test and laboratory experi- mentsof the coal gangue and expansive soil, the physical and mechanical properties were studied. Using numerical simulation method, we discussed the influence of coal gangue replacement ratio on settlement of expansive soil roadbed with different moisture content. The following results are achieved. The mechanical properties of expansive soil in Heshan area are affected by water greatly, so the expansive soil needs to be replaced. The gangue gradation in Heshan area is well-distributed, easy to be compacted, and suitable for subgrade filling materials. Under the action of load, the settlement curve of the expansive soil is symmetri- cal in the whole, and the settlement in the middle part is larger than that in the two sides. For semi-cut subgrade cross-section form, from the same distance from the center line of the road location, the settle- ment of the road near the lower side of the slope is larger. With the increase of replacement ratio, the fluc- tuation range of road settlement and road surface subsidence in the same location is gradually reduced. Ac- cording to the simulation results, it is suggested that the roadbed of expansive soil in Heshan City should be filled with 3.5 m thick coal gangue.