土壤壓實建設中的重要性[避免錯誤]

壓實是施工任務之一，實際上發生在每個建築項目中。無論是在地麵上致密地致密土壤還是壓縮土壩的粘土核心，你將需要壓實。

Therefore, it is important that we understand how compaction works, what it really is, how we can do it and monitor its quality and what mistakes, we should avoid while doing it. You will find answer to all these question in this article.

Contents

What is Compaction

壓實被定義為通過去除空隙來增加土壤密度的過程。它是通過機械手段完成的。壓實不應與合並混淆，這是由於利用土壤的水分含量的土壤密度的增加。A是一種受土壤滲透率控製的時間依賴過程。

Projects Where We Need Compaction

土壤壓實很重要，因為它為不同類型的項目提供了必要的平底基礎。壓實提供穩定性和堅實地支持建築，構建在它們上方。它還增加了土壤的剪切力量。

Compaction is frequently used on following projects:

建築物（基金會）
高速公路（基地，子巴士，路基，堤防）
Pavements
地球水壩
溝渠和回填

The Risks of Not Compacting

在網站上跳過壓實，基本要求它可能導致嚴重問題。

由於承載能力減少，土壤可以在負荷下沉降。土壤也可以滑下，使水在基礎表麵下方通過。

This movement, of course, can cause damage to building foundations in the form of erosion and can also cause additional uplift pressure.

Ultimately this would lead to building settling down and can also collapse. Similarly, in roads, an improper compaction can result is settlements of pavements and cracking in the pipes underneath the road.

Compaction and Moisture Content

水分含量

在解釋壓實和水分含量之間的關係之前，了解真正的水分含量是重要的。要在單句中定義它，水分含量是土壤中含有的水量。

Compaction and Moisture Content

在壓實中，主要目標是通過去除空隙來保持土壤顆粒盡可能接近。這導致土壤幹燥密度改善。

However, the maximum dry density in soil can only be achieved at a certain moisture content in soil, which is called optimum moisture content.

Hence compaction of soil depends on the relationship between its dry density and moisture content.

最優米oisture Content

When dry soil is compacted, the soil particles start to come close to each other and the soil becomes stiff and cracks and gaps are formed. These cracks are due to improper contact of dry soil particles.

如果我們將水加入土壤，水將在土壤顆粒周圍形成薄層，這有助於顆粒正確地彼此接觸。因此，土壤變得壓實濃度。

在某種程度上，土壤中的空氣量變為最小，幹密度將變得最大。這稱為最大幹燥密度點。在此目的之外，不應添加更多的水，並且在該階段土壤的水分含量是最佳的水分含量。

土壤壓實測量

通過以下技術可以測量土壤中的壓實

核心測試
Sand replacement
核衡量

95% Compaction

在建築項目中，您還在從現場采取的實驗室中測試小土壤樣品。從測試開始，您可以獲得最大幹密度的值。讓我們稱之為D.

Then you go to the construction sites and measure the compaction there. You also obtain a value of maximum dry density at site. It should not be less than the 90-95 % of the maximum dry density computed in laboratory (D).

因此，95％壓實意味著土壤壓實最多95的最大幹重（在實驗室計算為最大幹密度）。

不同類型的土壤壓實

Four different techniques are used to achieve compaction: Vibration, impact, kneading and applying pressure. These four techniques can use either static or vibratory force. Static force uses the weight of machine while vibratory force uses the mechanically driven force.

For topsoil layers, static techniques like kneading and pressure are well suited.
更深的土壤需要動態技術，如振動和影響方法。

用於壓實的機器類型

The type of machines we can use for compaction depends on the types of soils, we are compacting and the site conditions. Soils are categorized into different types based on their grain sizes. As a result, these soils have different densities and moisture contents.

Soils can be grouped into following types:

凝聚力的土壤

Soil particles stick together. High impact compaction is the best choice. Clay is a type of cohesive soil.

Granular Soils

Soil particles are bigger in size than the clay particles. These soils offer good drainage. Shaking or vibratory compaction technique is the best choice. Sand or gravel is a type of granular soil

Granular and Cohesive Soils

A combination of both types of soils (granular and cohesive). Most of the soil particles type (either granular or cohesive) determine the best strategy for their compaction.

Compaction Equipment

Following types of compaction equipment are available in market.

Plate compactors
馴服夯
Sheepsfoot compactors
Smooth wheel rollers
Vibratory rollers
氣動輪胎滾筒
溝槽滾筒
Reversible plate compactors
Tow behind compactors
前板壓實工具
Grid rollers

Compaction Mistakes You Should Avoid

Two most common compaction mistakes you should avoid are over compaction and under compaction. They are usually the result of untrained or careless work.

過度壓實

A general idea in our minds is that we can not over compact the soil. As we increase the compaction it will become more and stronger.

但這種情況並非如此。除了需要的壓縮會導致土壤顆粒分解。由於土壤混合中發生的分離，它將降低其支持能力。這將導致土壤中的弱點，而不是力量。

To make it further clear, you can perceive it like this. Let’s suppose, you have a pile of small rocks and you try to hammer them down into small pieces. You can do it with the correct amount of force.

但是，如果你堅持你想要的岩石的大小，你將最終讓它們在非常小的尺寸粒子上，如沙子，完全不同於你想要的

Over compaction breaks down the materials to such extent that their composition is changed.

在壓實下

Under compaction can happen as result of certain mistakes:

Not using large enough piece of equipment that can handle the job will result in under compaction.
Not making enough passes with the compactor may also result in under compaction.

在壓縮下會導致不均勻的定居點。由於土壤不正確壓實，因此它將無法承受高於它的重量，這可能導致結構問題。