土力学教材(Word版）.doc

三、土的结构
    土的结构是指土粒（或团粒）的大小、形状、互相排列及联结的特征。
土的结构是在成土的过程中逐渐形成的，它反映了土的成分、成因和年代对土的工程性质的影响。土的结构按其颗粒的排列和联结可分为图1-3所示的三种基本类型。
 
                                                                                        图1-3 土的结构的基本类型
1．单粒结构
单粒结构是碎石土和砂土的结构特征。其特点是土粒间没有联结存在，或联结非常微弱，可以忽略不计。疏松状态的单粒结构在荷载作用下，特别在振动荷载作用下会趋向密实，土粒移向更稳定的位置，同时产生较大的变形；密实状态的单粒结构在剪应力作用下会发生剪胀，即体积膨胀，密度变松。单粒结构的紧密程度取决于矿物成分、颗粒形状、粒度成分及级配的均匀程度。片状矿物颗粒组成的砂土最为疏松；浑圆的颗粒组成的土比
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