Đang chuẩn bị liên kết để tải về tài liệu:
SOIL MECHANICS - CHAPTER 27

Nhấn mạnh, biến dạng đàn hồi Một lớp quan trọng của vấn đề cơ học đất là việc xác định những căng thẳng và sự biến dạng trong một cơ thể đất, bởi các ứng dụng của một tải trọng nhất định. Tải có thể là kết quả của việc xây dựng một đường, đê điều, hoặc là nền tảng của một tòa nhà. Tải thực tế có thể là trọng lượng của cấu trúc, nhưng nó cũng có thể bao gồm các lực lượng do lưu lượng truy cập, tải trọng sóng, hoặc trọng lượng của hàng hoá được lưu. | Chapter 27 ELASTIC STRESSES AND DEFORMATIONS An important class of soil mechanics problems is the determination of the stresses and deformations in a soil body by the application of a certain load. The load may be the result of construction of a road a dike or the foundation of a building. The actual load may be the weight of the structure but it may also consist of the forces due to traffic wave loads or the weight of the goods stored in a building. The stresses in the soils must be calculated in order to verify whether these stresses can be withstood by the soil i.e. whether the stresses remain below the failure criterion or in order to determine the deformations of the soil which must remain limited. 27.1 Stresses and deformations A three dimensional computation of stresses and deformations in general involves three types of equations equilibrium constitutive relations and compatibility. For soils the main difficulty is that the constitutive relations are rather complicated and that their accurate description and formulation requires a large number of parameters which are not so easy to determine and which must be determined for every soil anew. In principle this should include the non-linear behavior of soils both in compression and in shear and possible effects such as time dependence creep dilatancy contractancy and anisotropy. The calculation of the real stresses and deformations in a soil is a well nigh impossible task for which advanced numerical models are being developed. Such models usually based upon the finite element method are applied very often in engineering practice and it can be expected that their use will be further expanded. As an introduction into the methods of analysis the problem will be severely schematized here and will be kept as simple as possible by assum ing that the material is isotropic linear elastic. This means that it is assumed that the relation between stresses and strains is described by Hooke s Figure 27.1 Load. law. This .