1. Coulomb's Eq.(1) is generally used to solve the equiblium equations of traction in soil. Such Coulomb's equation as is based on frictional phenomena could not be applied to all cases of mechanical behaviors. Soils, except sandy soil, in ordinary conditions are signified as viscoelastic bodies, which written in the form (Burgers' model) e=P0/G1+P0t/η1+p0/G2 [1-exp(-t/τυ)] where τυ, is time of retardation, and visualized with mechanical models in Fig. 13. For example, the model constants of the soil at pF=2.0 are showed in page 34. The flow of soil paste in the range of -1.5 < pF <1.5 is written in the form of Eq.(10), in which thixotropy flow generally occures. 2. Energy concept of soil water was studied by Schofield or Derjaguin which are written in the form of Eq.(12). In mechanical phenomena external force pe is equivalent to phase pressure, to soil water and equals to p in υΔp=Δμ, where μ is chemical potential of soil water. Therefore mechanical properties of soil is classified from the view-point of pF as showed in the Table (page 35). 3. Ultimate bearing strength of ground or foundation and trafficability of vihicles correspond to yield value θ of Bingham model linked in series to Burgers model. It is very useful in practical engineering that log θ is equivalent to pF value. Such mechanical constants as elasticity G and viscosity η are reduced in order of the increase of external force. The behavior of land slide may be treated as plastic flow (Eq.10). In the case of earthquake, ground surface of back marsh is suffered from thinning action and differential settlements are occured.