大厚度黄土地区单击夯击能影响强夯加固效果的试验研究

Experimental Study on the Effect of Single Tamping Energy onDynamic Compaction Reinforcement inLarge-Thickness-Loess Area

摘要:

针对黄土丘陵地区高填方下大厚度黄土地基强夯加固参数及效果开展了系列试验研究，分析了强夯前、后各试验区平均夯沉量和土体主要物理力学指标的变化规律，并给出6 000、8 000、10 000、12 000 kN·m能级条件下强夯加固的夯点中心距、击数、有效加固深度等主要参数，在此基础上确定了强夯有效加固深度的估算方法。试验结果表明，加固后黄土的孔隙比、干密度和湿陷系数可作为强夯加固效果的评价指标；强夯处理后地基土的物理力学指标在满足设计要求时其下限深度即为有效处理深度；在湿陷性大厚度黄土地区，以夯点土和夯间土湿陷性均消除的地基土下限深度可作为有效处理深度。

Abstract:

A series of tests was carried out to study the dynamic compaction parameters of a large-thickness-loess foundation in a loess hilly region. The average settlement of each test area before and after dynamic compaction and the change law of the main physical and mechanical indexes of soil were analyzed. The main parameters were gained, such as the center distance of dynamic compaction points, impact number, and the effective reinforcement depth under energy levels of 6 000, 8 000, 10 000, and 12 000 kN·m. Hence, the empirical method of determining the effective reinforcement depth of dynamic compaction was given. The test results showed that the void ratio, dry density, and collapsibility coefficient of the reinforced loess can be used as the evaluation indexes of the reinforcement effect. If the physical and mechanical indexes of the ground soil after dynamic compaction meet the design requirements, the lower limit depth is the effective reinforcement depth. In the collapsible loess area with large overburden thickness, the lower limit depth of foundation soil after eliminating the collapsibility can be used as the effective reinforcement depth