赵家琛 吕江 赵晖 孙宏磊

摘 要：高能级强夯的加固效果显著，应用范围越来越广泛，有效加固深度是评判加固效果和确定强夯方案的重要指标。以10 000 kN·m高能级强夯加固某抛填路基工程为背景，采用FLAC 3D有限差分软件进行单点多次夯击的强夯数值模拟，以夯击后的应力为标准来计算有效加固深度。结果表明：随夯击次数的增加，有效加固深度先增大后稳定，6击后有效加固深度的增幅极小。经正交试验和极差分析得到土体参数对强夯有效加固深度的敏感性排序。落距和锤重与有效加固深度呈正相关关系，锤径则为负相关关系。锤重对有效加固深度的影响大于落距，在夯击能相同时，重锤低落所得到的累计夯沉量与有效加固深度均更大。提出强夯有效加固深度估算公式，并实现了量纲统一，该公式与模拟结果偏差较小。

关键词：路基工程;抛填路基;高能级强夯;有限差分法;加固深度

Abstract： The reinforcement effect of high energy dynamic compaction is remarkable and its application is more and more widely. The effective reinforcement depth is an important index for evaluating the reinforcement effect and determining the dynamic consolidation plan. In this paper， taking a project of 10 000 kN·m high energy dynamic compaction for filled subgrade as a background， the finite difference software FLAC 3D was used to carry out numerical simulation of dynamic compaction at a single point multiple times. The effective reinforcement depth was calculated according to the stress after tamping. The results show that the effective reinforcement depth increases first and then becomes stable with the increase of tamping times. The growth rate of effective reinforcement depth after 6 times of tamping is extremely small. The sensitivity ranking of soil parameters to the effective reinforcement depth of dynamic compaction has been obtained by orthogonal test and extreme difference analysis. The drop distance and hammer weight are positively correlated with the effective reinforcement depth， while the hammer diameter is negatively correlated. The impact of hammer weight on the effective reinforcement depth is greater than the drop distance. The combination of heavy hammer and low drop distance has greater cumulative settlement and effective reinforcement depth under the same tamping energy. The formula for estimating the effective reinforcement depth of high energy dynamic compaction has been proposed and the dimensional unification has been realized. The deviation between the formula and the simulation results is small， which can be used as a reference for the same type of dynamic compaction projects.

Keywords：subgrade engineering; filled subgrade; high energy dynamic compaction; finite difference method; reinforcement depth

隨着交通运输工程建设持续发展，沿河流、山谷修建的公路日益增加，水下路基填筑及其强夯加固也成为必然研究的课题，对于此类工程，一般采用就地取材、开山填谷的方式回填并进行高能级强夯处理[1-2]。强夯法是一种效果显著、经济易行的地基处理及路基加固方法，自1969年Menard等[3]首创强夯法以来，发展迅速，现已推广应用到从粘性土到块石的各类地基中[4-6]。强夯有效加固深度是体现加固效果的重要指标，也是选定强夯处理方案的重要依据。对于夯击能大于6 000 kN·m的高能级强夯，相关规范[7]指出，有效加固深度需通过现场试夯或当地经验确定，同时给出了梅纳公式修正系数的参考范围，但在应用中还存在参数选取困难、结果与实际偏差较大等问题。……