黄土是由沙砾、粗粉粒、大孔隙胶结构组成，黄土湿陷性是由于水和外力的作用产生的显著附加下沉。强夯是将大吨位重锤起吊到一定高度后自由落下，在极短时间内对地基土体施加一个巨大的冲击能量，反复冲击及其产生的压缩波、剪切波和瑞利波，使土体受到瞬间的加荷（受压）、卸荷（受拉）及剪切的反复作用，土中孔隙压缩，同时土体周围产生裂隙，孔隙水顺利排出，土体迅速固结，使土粒原有的接触形式破坏而产生位移，变为新的较为稳定的接触形式，从而达到增加土体密度、提高强度的目的。
Loess is composed of gravel, coarse silt and macroporous glue. The collapsibility of loess is due to the significant additional subsidence caused by the action of water and external forces. Dynamic compaction is to lift a heavy hammer of large tonnage to a certain height and then drop freely. In a very short period of time, it exerts a huge impact energy on the foundation soil. The repeated impact and the compression wave, shear wave and Rayleigh wave produced by the repeated impact make the soil subjected to instantaneous loading (compression), unloading (tension) and shear, and the pore in the soil is compressed. At the same time, cracks and voids are formed around the soil. The water is discharged smoothly and the soil is consolidated rapidly, which destroys the original contact form of the soil and causes displacement, and becomes a new and more stable contact form, thus achieving the purpose of increasing the density and strength of the soil.