The mechanism of strengthening collapsible loess by small dynamic compaction machine: loess is composed of gravel, coarse silt and macroporous rubber structure, and collapsibility of loess is a significant additional subsidence caused by water and external force. Dynamic compaction is to lift the heavy hammer of large tonnage to a certain height and drop it freely.

在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。

In a short period of time, a huge impact energy is applied to the foundation soil. The repeated impact and the generated compression wave, shear wave and Rayleigh wave make the soil subject to the repeated action of instantaneous loading (compression), unloading (tension) and shear. The pores in the soil are compressed. At the same time, cracks are generated around the soil, the pore water is discharged smoothly, and the soil is consolidated rapidly, So that the original contact form of soil particles will be destroyed and displacement will be produced, which will become a new and more stable contact form, so as to increase the density and strength of soil.

小型强夯机对回填土要求较高，小型强夯机，要考虑回填土中是否含有膨胀物质。小型强夯机施工的目的是为了提高地基土的承载力，降低土体的压缩度，避免后期出现不均匀沉降。

Small dynamic compaction machine has higher requirements for backfill soil. Small dynamic compaction machine should consider whether the backfill soil contains expansive material. The purpose of small dynamic compaction machine construction is to improve the bearing capacity of foundation soil, reduce the compressibility of soil, and avoid the late uneven settlement.

如果回填土中含有膨胀体的话，小型强夯机出租，地基的不稳定性增加，对后期建筑物的基础结构有着严重的影响。小型强夯机施工时考虑震动，小型强夯机施工会产生较大的震动，小型强夯机租赁，如地下水较浅，震动会以水为介质传播。震动的衰减较小，会让震动的破坏性增加。

If the backfill soil contains expansive body, the small dynamic compaction machine will increase the instability of the foundation, which has a serious impact on the foundation structure of later buildings. Vibration is considered in the construction of small dynamic compaction machine. The construction of small dynamic compaction machine will produce large vibration. If the underground water is shallow, the vibration will be transmitted by water. The attenuation of vibration is small, which will increase the destructiveness of vibration.

考虑抗浮。地下水位较浅，在结构设计时需要考虑抗浮。在小型强夯机处理地下水较浅的回填层时，需要考虑到降水强夯机方案，将地下水位降低到地下2-5米，再开始小型强夯机施工，会有较好的效果。

Consider anti floating. Due to the shallow groundwater level, anti floating should be considered in structural design. When the small dynamic compaction machine is used to treat the backfill layer with shallow groundwater, it is necessary to consider the scheme of dewatering dynamic compaction machine. It will have a good effect to reduce the groundwater level to 2-5M underground and then start the construction of small dynamic compaction machine.

对强夯机效果的影响，特别是细颗粒土，含水较高饱和后，小型强夯机效果会降低，无法大道设计的要求。如果形成淤泥会造成橡皮土。对强夯机施工有非常大影响。

The impact on the effect of dynamic compaction machine, especially for fine-grained soil, when the water content is high and saturated, the effect of small dynamic compaction machine will be reduced, which can not meet the design requirements. If silt is formed, it will cause rubber soil. It has a great influence on the construction of dynamic compaction machine.