Nowadays, the foundation of construction projects need to be compacted, which is inseparable from ramming. Small construction projects can be tamped with small electric rammer. Large construction projects usually have rigid indexes for the foundation, which need to be tamped to a certain extent before they are qualified. In this way, the rammer has certain index requirements, Therefore, we need to use dynamic compaction machine.

强夯法即强力夯实法，又称动力固结法。是利用大型履带式强夯机将8-30吨的重锤从6-30米高度自由落下，对土进行强力夯实，迅速提高地基的承载力及压缩模量，形成比较均匀的、密实的地基，在地基一定深度内改变了地基土的孔隙分布。

Dynamic compaction method is also called dynamic consolidation method. It is to use large crawler dynamic compaction machine to drop 8-30 tons of heavy hammer freely from 6-30 meters to tamp the soil strongly, rapidly improve the bearing capacity and compression modulus of the foundation, form a relatively uniform and dense foundation, and change the pore distribution of the foundation soil within a certain depth of the foundation.

强夯法施工已广泛运用到高速公路铁路，机场、核电站、大工业区、港口填海等基础加固工程。优点工期短、效果好、造价低。

Dynamic compaction method has been widely used in highway, railway, airport, nuclear power station, large industrial area, port reclamation and other foundation reinforcement projects. The utility model has the advantages of short construction period, good effect and low cost.

强夯法适用于处理碎石土、砂土、低饱和度的粉土与粘性土、湿陷性黄土、素填土和杂填土等地基。强夯施工前，应在施工现场有代表性的场地上选取一个或几个试验区，进行试夯或试验性施工。试验区数量应根据建筑场地复杂程度、建设规模及建筑类型确定。

The dynamic compaction method is suitable for the treatment of gravel soil, sandy soil, silt and cohesive soil with low saturation, collapsible loess, plain fill and miscellaneous fill. Before dynamic compaction, one or several test areas should be selected on the representative site of the construction site for trial compaction or trial construction. The number of test areas should be determined according to the complexity of construction site, construction scale and building type.

强夯法的三种不同加固机理

Three different reinforcement mechanisms of dynamic compaction

1、动力固结：当强夯法应用于处理细颗粒饱和黏土时，其加固机理则是动力固结理论。强夯时，巨大的冲击能量在土中产生很大的应力波，破坏土体的原有结构，使土体局部发生液化并产生许多裂隙，增大了排水通道，使孔隙水顺利逸出，待超孔隙水压力消散后，土体固结。由于软土的触变性，强度得到恢复。（安利一下，触变性是指含水率不变情况下黏土因为重塑而软化，强度降低，软化后随着静置时间延长而硬化，强度增长的性质）

1. Dynamic consolidation: when dynamic consolidation method is used to treat fine-grained saturated clay, its reinforcement mechanism is dynamic consolidation theory. During dynamic compaction, the huge impact energy produces a large stress wave in the soil, destroys the original structure of the soil, liquefies the soil locally and produces many cracks, increases the drainage channel, and makes the pore water escape smoothly. After the excess pore water pressure dissipates, the soil consolidates. Because of the thixotropy of the soft soil, the strength is restored（ Amway: thixotropy refers to the property that clay softens due to remolding and its strength decreases under the condition of constant moisture content. After softening, it hardens with the extension of standing time and its strength increases.)

2、动力密实：采用强夯法加固多孔隙、粗颗粒、非饱和黏土是基于动力密实的机理，即冲击型动力荷载，使土体中的孔隙减小，土体变得密实，从而提高地基土强度。非饱和土的夯实过程，就是土中的气相（空气）被挤出的过程，其夯实变形主要是由于土颗粒的相对位移引起。

2. Dynamic compaction: the dynamic compaction method is used to reinforce porous, coarse-grained and unsaturated clay based on the mechanism of dynamic compaction, that is, the impact dynamic load reduces the pores in the soil and makes the soil dense, so as to improve the strength of foundation soil. The compaction process of unsaturated soil is the process in which the gas phase (air) in soil is squeezed out, and the compaction deformation is mainly caused by the relative displacement of soil particles.

3、动力置换：动力置换可分整式置换和桩式置换。整式置换是采用强夯将碎石整体挤入淤泥中，其作用机理类似于换土垫层。桩式置换是通过强夯将碎石填入土中，部分碎石桩（或墩）间隔地夯入软土中，形成桩式（墩式）的碎石桩（墩），其作用机理类似于振冲法形成的碎石桩，整体形成复合地基。

3. Dynamic replacement: dynamic replacement can be divided into integral replacement and pile replacement. Integral replacement uses dynamic compaction to squeeze the gravel into the silt, and its mechanism is similar to that of soil replacement cushion. Pile replacement is to fill gravel into soil by dynamic compaction, and part of gravel piles (or piers) are rammed into soft soil at intervals to form pile (pier) gravel piles (piers). Its mechanism is similar to that of gravel piles formed by vibroflotation method, forming composite foundation as a whole.