镍铁渣加筋路堤填筑方法及足尺试验

通过室内试验和现场足尺试验研究了镍铁渣加筋路堤的填筑方法及应用效果。首先，通过现场取样测试了广青镍铁渣的化学成分、环境影响特性及其工程材料特性。其次，提出了基于土工格栅加筋和改性土包边的镍铁渣路堤断面形式，总结了施工工艺。然后，开展了镍铁渣加筋路堤现场足尺试验，获得了镍铁渣加筋路堤施工期及工后的沉降量、水平位移、土压力及孔隙水压力的变化规律曲线。结果表明：土工格栅加筋填筑后的镍铁渣密度为1.76~1.88 g·cm^-3，平均压实度可达93.0%。各层镍铁渣的沉降主要发生在施工期，工后沉降和沉降速率均较小。施工期最大沉降为26.24 mm，发生在路堤中部第2层镍铁渣处，小于预测值40.60 mm；实测路堤总沉降最大值为55.51 mm，小于预测值73.50 mm。上路堤施工导致第5层镍铁渣局部产生了29.64 mm水平位移，但工后各层镍铁渣的水平位移几乎为0。各层镍铁渣底的土压力呈阶梯形变化，土压力实测值与理论值吻合较好；上路堤施工对第4，5层镍铁渣影响较大，可在下路堤顶面以下1.5 m范围内增设土工格栅。厂区重车荷载传递到各层镍铁渣底的附加应力较小，路堤安全稳定性较好。上述研究表明，广青镍铁渣属于一般固体废弃物，排水性良好，浸水膨胀率低，对环境无毒害，经加筋处治后，可直接入场（非预处理）填筑，其变形和稳定性均满足路用要求。

Construction Methodology of Full-scale Experimental Ferronickel Slag in Reinforced Embankment

The construction methodology and quality of a ferronickel slag reinforced embankment were studied using laboratory tests and full-scale experiments. First, the chemical composition, environmental impact, and engineering properties of Guangqing ferronickel slag were sampled and tested. Second, a typical section of a Ferronickel slag embankment, reinforced by a geogrid and covered using modified soil, was proposed. The construction strategy was summarized accordingly, followed by full-scale field tests of a ferronickel slag reinforced embankment. The development of settlement, horizontal displacement, earth pressure, and pore water pressure in each layer during construction and in-service were measured. The monitoring results indicate that the density of Ferronickel slag ranges between 1.76 and 1.88 g·cm^-3, and achieves an average compaction degree of 93.0%. The settlement in each layer is mainly observed during construction, as settlement and its rate during in-service stage is negligible. During construction, the second layers of ferronickel slag indicated the largest settlement values of 26.24 mm. These values are less than the predicted settlement value of 40.60 mm. The maximum total settlement measured in the embankment is 55.51 mm, which is less than the predicted value of 73.50 mm. The construction of the upper embankment resulted in 29.64 mm of horizontal displacement in the fifth layer of the Ferronickel slag, which is close to zero after construction. The earth pressure at the bottom of each layer develops in steps, and agrees with the calculated results. The construction of the upper embankment has a significant influence on the lower layers; thus, it is recommended that a geogrid be adopted at 1.5 m below the upper embankment. The stress incurred from heavy vehicle loading at the bottom of each layer is insignificant; therefore, the embankment is considered safe and stable. The research indicates that Guangqing ferronickel slag can be termed general solid waste with free drainage and low swelling index, and is environmentally friendly. While ferronickel slag usually has poor particle size distribution, it can be reinforced and adopted as fill (non-pretreated), hence meeting the requirements of deformation and stability in road engineering.