液压强夯法补强黄土路基压实质量控制方法

Quality control method of hydraulic dynamic compaction reinforcing loess subgrade

为提出一种黄土路基施工时不同深度处压实质量实时监测方法,依托黄延(黄陵—延安)高速公路扩能工程,首先引入液压加力系数,建立液压强夯法的夯击模型,进行液压强夯法补强黄土路基的室内足尺模型试验研究。考虑液压夯实机的夯锤落距和夯击次数对路基压实度的影响,通过在夯锤顶面中心处布置加速度传感器并在补强结束后分层开挖路基,获取夯锤单击峰值加速度和路基的分层沉降量,分析不同工况下夯锤峰值加速度与表层土体沉降量之间的关系,以土体分层沉降量达到表层土体沉降量5%处的路基深度为研究对象,通过线性内插法和回归分析法,分析不同工况下液压强夯法补强黄土路基的有效加固深度,确定路基分层压实度与夯锤峰值加速度的关系式。研究结果表明:夯锤峰值加速度与表层土体沉降量均随夯击次数和夯锤落距的增加而增加,在夯击次数达到6击和7击以上时,其增长趋势都显著放缓,从定性上说明夯锤峰值加速度可以实时反映路基的压实质量;液压夯实机有效加固深度受夯锤落距的影响较夯击次数大,当夯击次数达到12击时,对应夯锤落距为2.2、1.6、0.7 m的有效加固深度分别为1.49、1.18、1.10 m;考虑有效加固深度范围,定量说明不同工况下夯锤峰值加速度与路基分层压实度间存在二次函数关系,将路基分层压实度按填筑深度加权平均得到了路基的平均压实度。

To provide a real-time monitoring method of the degree of compaction at different depths during the construction of the loess subgrade,the hydraulic force coefficient was introduced,and the hydraulic dynamic compaction model was established,rely on the capacity expansion project of Huangling to Yan’an Expressway,and the indoor full-scale model test of the hydraulic compactor reinforcing the loess subgrade was carried out.Considering the impact of the dropping distance and the dropping numbers of the hydraulic rammer on the degree of compaction of the subgrade,the peak acceleration of rammer and the layered settlement of the subgrade were obtained,by arranging acceleration sensors in the center of the top surface of the rammer and excavating the subgrade layer by layer after the reinforcement.The correlation between the settlement of surface soil and the peak acceleration of hydraulic rammer under different working conditions were analyzed.The subgrade depth which settlement was 5%of the soil surface settlement was used as the research object,the effective reinforcement depth of hydraulic compactor in different working conditions were analyzed through linear interpolation method and regression analysis method.And the relationship between the degree of compaction of subgrade in layers and the peak acceleration of rammer was determined.The results show that the peak acceleration of rammer and the settlement of surface soil increase with the increase of dropping numbers and dropping distance,and the increase trend slows down obviously after 6 and 7 dropping numbers,which qualitatively indicates that the peak acceleration of rammer can reflect the compaction quality of subgrade in real time.The effective reinforcement depth of hydraulic compactor is more affected by the dropping distance than dropping numbers of rammer.When dropping numbers reaches 12,the effective reinforcement depth corresponding to the dropping distance of 2.2,1.6 and 0.7 m is 1.49,1.18 and 1.10 m,respectively.Considering the range of effective reinforcement depth,there is a quadratic function relationship between the peak acceleration of rammer and the degree of compaction of subgrade in layers under different working conditions.The average degree of compaction of subgrade is obtained by weighted average of the layered degree of compaction.4 tabs,13 figs,29 refs.