土力學教材(Word版）.doc

三、土的結構
    土的結構是指土粒（或團粒）的大小、形狀、互相排列及聯結的特征。
土的結構是在成土的過程中逐漸形成的，它反映了土的成分、成因和年代對土的工程性質的影響。土的結構按其顆粒的排列和聯結可分為圖1-3所示的三種基本類型。
 
                                                                                        圖1-3 土的結構的基本類型
1．單粒結構
單粒結構是碎石土和砂土的結構特征。其特點是土粒間沒有聯結存在，或聯結非常微弱，可以忽略不計。疏松狀態的單粒結構在荷載作用下，特別在振動荷載作用下會趨向密實，土粒移向更穩定的位置，同時產生較大的變形；密實狀態的單粒結構在剪應力作用下會發生剪脹，即體積膨脹，密度變松。單粒結構的緊密程度取決于礦物成分、顆粒形狀、粒度成分及級配的均勻程度。片狀礦物顆粒組成的砂土最為疏松；渾圓的顆粒組成的土比
Third, the structure of soil
    Soil structure refers to the soil particle (or aggregate) size, shape, mutual arrangement and connection features.
The structure of soil into the soil in the process of evolving, it reflects the soil composition, origin and age of the engineering properties of soil. The structure of soil particles according to the arrangement and connection can be divided into as shown in Figure 1-3 are three basic types.
 
                                                                                        Figure 1-3 The structure of the basic types of soil
1. Single grain structure
Single grain structure is the stone structure of soil and sand. It features no connection exists between Soil Particles, or association is very weak, negligible. Loose state of the single grain structure under load, particularly in vibration loads will tend to compact, Soil particles move to a more stable position, and have a greater deformation; dense state of single grain structure will occur under shear stress dilatancy, that is, volume expansion, density loose. Single grain structure depends closely mineral composition, particle shape, particle size composition and size distribution uniformity. Sheet composed of mineral particles in the most loose sand; rounded than the particle composition of the soil

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