某特高土石坝高海拔料场防渗土料现场碾压试验研究

Field Experimental Study on Compaction Performance of Impervious Soil Material in High Altitude Borrow of an Ultra-high Earth-rockfill Dam

某特高土石坝防渗土料场位于3500 m高海拔地区,为获取防渗土料压实工艺参数,开展了现场碾压试验研究。试验内容包括土料碾压参数选择、变含水率对土料碾压特性的影响以及不同碾压方式压实效果对比研究。试验研究表明,碾压遍数相同情况下,铺土厚度为35 cm时压实效果最优,综合土料压实度设计指标与经济性等方面考虑,确定了防渗土料碾压参数:铺土厚度为30~35 cm、碾压设备为26 t自行式振动碾压机、碾压遍数为10遍。试验发现,土料铺填厚度较薄时,碾压遍数越多,对其造成的扰动效应越大,压实效果反而越差。结合料场气候条件,发现从装土至碾压完毕,土料含水率损失为1.2%。通过改变土料含水率,探究了含水率对土料压实效果的影响,确定了本工程土料的可碾含水率区间范围。不同碾压方式对比试验研究表明,不同铺土厚度、碾压遍数下,振动平碾所获得的压实度均要高于振动凸块碾。

An impervious soil material borrow of an ultra-high earth rock dam is located at an altitude of 3500 m.In-site compaction test of soil was carried out at this elevation.The tests include the selection of compaction parameters,the influence of variable moisture content on soil compaction characteristics,and the comparative study of compaction effects of different compaction methods.The experimental research shows that when the paving thickness of soil is 35 cm,the greatest degree of compaction is acquired.Considering the design index of soil compaction and cost,the paving thickness is determined as 30~35 cm and rolling times is 10.It is found that when the thickness of soil material is thin,the more rolling times,the greater the disturbance and the worse the compaction degree.Combined with the climatic conditions of the soil borrow,it is found that the loss of soil moisture content is 1.2%in the whole process from soil loading to compaction.By changing the moisture content of soil,the influence of moisture content on the compaction effect is explored,and the range of compactable moisture content of soil in the project is determined.The comparative experimental study of different compaction methods shows that the compaction degree obtained by vibratory flat roller is higher than that by vibratory bump roller under different paving thickness and rolling times.