Soil mechanics is a discipline that applies principles of engineer－ ing mechanics，e．g，kinematics，dynamics，fluid mechanics，and mechanics of material，to predict the mechanical behavior of soils． Together with Rock mechanics，it is the basis for solving many engi－ neering problems in civil engineering（geotechnical engineering），ge－ ophysical engineering and engineering geology．Some of the basic the－ ories of soil mechanics are the basic description and classification of soil，effective stress，shear strength，consolidation，lateral earth pres－ sure，bearing capacity，slope stability，and permeability．Founda－ tions，embankments，retaining walls，earthworks and underground o－ penings are all designed in part with theories from soil mechanics
土力学是一门应用工程力学原理的学科，例如运动学、动力学、流体力学和材料力学，来预测土壤的力学行为。它与岩石力学一起，是解决土木工程（岩土工程）、地质物理工程和工程地质学中许多工程问题的基础。地基、堤防、挡土墙、土方工程和地下 open 结构在一定程度上都设计了土壤力学理论

Soil is usually composed of three phases：solid，liquid，and gas． The mechanical properties of soils depend directly on the interactions of these phases with each other and with applied potentials（e．g．， stress，hydraulic head，electrical potential，and temperature differ－ ence）．
土壤通常由三个相组成：固体、液体和气体。土壤的机械性能直接取决于这些相彼此之间的相互作用以及与施加的电位（例如，应力、水力水头、电位和温差）的相互作用。

The solid phase of soils contains various amounts of crystalline clay and non－clay minerals，noncrystalline clay material，organic mat－ ter，and precipitated salts．These minerals are commonly formed by
土壤的固相包含不同数量的结晶粘土和非粘土矿物、非结晶粘土材料、有机材料、沉淀盐。
atoms of elements such as oxygen, silicon, hydrogen, and aluminum, organized in various crystalline forms. These elements along with calcium, sodium, potassium, magnesium, and carbon comprise over $99\mathrm{\%}$$99\mathrm{\%}$99%99 \% of the solid mass of soils. Although, the amount of non-clay material is greater than that of clay and organic material, the latter have a greater influence in the behavior of soils. Solid particles are classified by size as clay, silt, sand, gravel, cobbles, or boulders.
氧、硅、氢和铝等元素的原子，以各种晶体形式组织。这些元素与钙、钠、钾、镁和碳一起构成了 $99\mathrm{\%}$$99\mathrm{\%}$99%99 \% 土壤的固体质量。虽然非粘土材料的数量大于粘土和有机材料的数量，但后者对土壤行为的影响更大。固体颗粒按大小分为粘土、淤泥、沙子、砾石、鹅卵石或巨石。

The liquid phase in soils is commonly composed of water containing various types and amounts of dissolved electrolytes. Organic compounds, both soluble and immiscible are present in soils from chemical spills, leaking wastes, and contaminated groundwater.
土壤中的液相通常由含有各种类型和数量的溶解电解质的水组成。有机化合物，包括可溶性和不混溶性，都存在于化学品泄漏、泄漏废物和受污染的地下水的土壤中。

The gas phase, in partially saturated soils, is usually air, although organic gases may be present in zones of high biological activity or in chemically contaminated soils ${}^{[1]}$${}^{[1]}$^([1]){ }^{[1]}.
在部分饱和土壤中，气相通常是空气，尽管有机气体可能存在于高生物活性区域或化学污染的土壤 ${}^{[1]}$${}^{[1]}$^([1]){ }^{[1]} 中。

Soil mineralogy controls the size, shape, and physical and chemical properties of soil particles and thus its load-carrying ability and compressibility.
土壤矿物学控制土壤颗粒的大小、形状和物理化学性质，从而控制其承载能力和可压缩性。

The structure of a soil is the combined effects of fabric (particle association, geometrical arrangement of particles, particle groups, and pore spaces in a soil), composition, and interparticle forces. The structure of soils is also used to account for differences between the properties of natural (structured) and remolded soils (destructured). The structure of a soil reflects all facets of the soil composition, history, present state, and environment. Initial conditions dominate the structure of young deposits at high porosity or freshly compacted soils; whereas older soils at lower porosity reflect the post-depositional changes more.
土壤的结构是织物（土壤中颗粒的关联、颗粒的几何排列、颗粒组和孔隙空间）、成分和颗粒间力的综合作用。土壤的结构也用于解释天然（结构性）和重塑土壤（解构性）特性之间的差异。土壤的结构反映了土壤成分、历史、现状和环境的所有方面。初始条件在高孔隙度或新压实土壤的年轻矿床的结构中占主导地位;而孔隙度较低的老土壤更能反映沉积后的变化。

Soil, like any other engineering material, distorts when placed under a load. This distortion is of two kinds - shearing, or sliding,
与任何其他工程材料一样，土壤在承受负载时会变形。这种变形有两种 - 剪切或滑动，
distortion and compression. In general, soils cannot withstand tension. In some situations the particles can be cemented together and a small amount of tension may be withstood, but not for long periods.
失真和压缩。一般来说，土壤不能承受张力。在某些情况下，颗粒可以粘合在一起，并且可以承受少量的张力，但不能长时间。

Particles of sands and many gravels consist overwhelmingly of silica. They can be rounded due to abrasion while being transported by wind or water, or sharp-cornered, or anything in between, and are roughly equi-dimensional ${}^{[2]}$${}^{[2]}$^([2]){ }^{[2]}. Clay particles arise from weathering of rock crystals like feldspar, and commonly consist of aluminosilicate minerals. They generally have a flake-shape with a large surface area compared with their mass. As their mass is extremely small, their behavior is governed by forces of electrostatic attraction and repulsion on their surfaces. These forces attract and adsorb water to their surfaces, with the thickness of the layer being affected by dissolved salts in the water.
沙子颗粒和许多砾石绝大多数由二氧化硅组成。它们在被风或水运输时可能会因磨损而变圆，或者是尖角的，或者介于两者之间的任何东西，并且大致是等维 ${}^{[2]}$${}^{[2]}$^([2]){ }^{[2]} 的。粘土颗粒由长石等岩石晶体的风化产生，通常由铝硅酸盐矿物组成。它们通常呈片状，与质量相比表面积较大。由于它们的质量非常小，因此它们的行为受其表面的静电吸引力和排斥力的控制。这些力将水吸引并吸附到它们的表面，层的厚度受水中溶解的盐分的影响。

The concept of effective stress is one of Karl Terzaghi’s most important contributions to soil mechanics. It is a measure of the stress on the soil skeleton (the collection of particles in contact with each other), and determines the ability of soil to resist shear stress. It cannot be measured in itself, but must be calculated from the difference between two parameters that can be measured or estimated with reasonable accuracy ${}^{[3]}$${}^{[3]}$^([3]){ }^{[3]}.
有效应力的概念是 Karl Terzaghi 对土壤力学最重要的贡献之一。它是土壤骨架（相互接触的颗粒集合）上应力的量度，并确定土壤抵抗剪切应力的能力。它本身不能测量，但必须根据两个参数之间的差异来计算，这些参数可以以合理的精度 ${}^{[3]}$${}^{[3]}$^([3]){ }^{[3]} 进行测量或估计。

Effective stress ( ${\sigma }^{\prime }$${\sigma }^{\prime }$sigma^(')\sigma^{\prime} ) on a plane within a soil mass is the difference between total stress ( $\sigma$$\sigma$sigma\sigma ) and pore water pressure ( $u$$u$uu ):
土体内平面上的有效应力 （ ${\sigma }^{\prime }$${\sigma }^{\prime }$sigma^(')\sigma^{\prime} ） 是总应力 （ $\sigma$$\sigma$sigma\sigma ） 与孔隙水压力 （ ） 之间的差 $u$$u$uu 值：

The total stress $\sigma$$\sigma$sigma\sigma is equal to the overburden pressure or stress,
总应力 $\sigma$$\sigma$sigma\sigma 等于覆盖层压力或应力