强夯法加固粉土路基现场试验研究

Field Test Study on Consolidation of Silty Subgrade by Dynamic Compaction

摘要: 依托典型黄泛区高速公路工程，开展了松铺高度为4 m的粉土路基强夯填筑试验研究，通过试验路测试，优化了相关工艺参数，分析了强夯法加固粉土路基的效果。结果显示，采用1500 kN∙m的夯击能填筑松铺高度为4 m的黄泛区粉土路基是可行的，其合理设计和工艺参数为夯击能采用1500 kN∙m，夯击数为10击，夯间距为3.2 m，土的含水率宜控制在最佳含水率的−5%~3%范围内；经多点夯、满夯之后，强夯路基的空间密度仍呈现不均匀分布，其中夯锤下的土体压实度略高于夯间2个百分点，上部土体的压实度则显著高于下部土体约6个百分点；夯后路基的平均静回弹模量约为52 MPa，其中夯间承载能力略低于夯锤以下约2.7 MPa；为保证路基支撑的均匀性，强夯路基上部应该设置一定厚度的均匀过渡层，强夯路基上部设置2 × 20 cm石灰处置土过渡层后，路基静回弹模量约提高1倍，路基支撑均匀。

Abstract: This paper performed experimental investigation on the dynamic compaction of a typical expressway silt roadbed with a height of 4 m in the Yellow River flooding area. Based on experimental achievement, relevant technological parameters were optimized and the effect of the dynamic compaction method on strengthening the silt roadbed was characterized. The results indicated that the lamping of 1500 kN·m is feasible to fill silt roadbed in Yellow River flooding area with the height of 4 m. The optimized tamping energy is 1500 kN·m with the tamper spacing of 3.2 m. The tamping number is controlled at 10 and the soil moisture content should be controlled in the optimal moisture content −5%~3% range. After multi-point compaction and full compaction, the spatial density of the dynamic compaction roadbed still presents an uneven distribution, among which the compaction degree of the soil under the rammer is slightly higher than 2%, while the compaction degree of the upper soil is 6% higher than that of the lower soil. The average static resilient modulus of the rammed roadbed is about 52 MPa, among which the load capacity between rammers is slightly lower than that under the rammer, about 2.7 MPa. In order to ensure the uniformity of subgrade support, a uniform transition layer of a certain thickness should be set at the upper part of the dynamic compaction subgrade. After setting a 2 × 20 cm lime treated soil transition layer at the upper part of the dynamic compaction subgrade, the static resilient modulus of the subgrade would be increased by about one time, and the subgrade support would be uniform.