Giáo trình cơ học đất - Chương 1

Soil, a fundamental material in geotechnical engineering, is a complex product of geological weathering processes, encompassing physical, chemical, and biological transformations. Its inherent variability and complex nature necessitate a rigorous scientific approach, forming the core of soil mechanics—an applied field dedicated to understanding its behavior. This introductory chapter lays the groundwork by defining the scope of soil mechanics, detailing the origins and characteristics of various soil types. It emphasizes the critical role of experimental methods in determining soil properties due to its dynamic and ever-changing nature. The objective is to establish a foundational understanding of soil as an engineering material, paving the way for advanced studies in its mechanical properties, classification, and practical applications in construction and infrastructure development.

Sinh viên kỹ thuật xây dựng, kỹ thuật địa kỹ thuật, hoặc các ngành liên quan, cũng như kỹ sư và nhà nghiên cứu cần nắm vững các nguyên lý cơ bản về cơ học đất và tính chất vật lý của đất.

This document provides a comprehensive overview of Cơ học đất (Soil Mechanics), beginning with its definition as an applied engineering science focused on understanding soil behavior. It elaborates on the genesis of đất through various phong hóa processes—physical, chemical, and biological—and describes the resulting fundamental characteristics such as granularity, porosity, and weak inter-particle bonds. A core emphasis is placed on the necessity of thí nghiệm đất (soil testing) to accurately determine its properties, given its inherent variability. The text then delves into Chương 1: Các tính chất vật lý của đất và phân loại đất, systematically covering soil formation, transportation, and deposition, which delineate different soil types like cohesive (sét) and non-cohesive (cát). It details phân loại đất based on geological origin, particle size distribution, and sedimentation methods, including the application of uniformity (Cu) and curvature (Cc) coefficients. The multi-phase nature of soil—comprising solid particles, water, and air—is thoroughly discussed, alongside the unique physicochemical properties of fine particles (e.g., surface area, electrical charges) that influence tính dính (cohesion) and soil structure. Key tính chất vật lý đất such as natural unit weight, moisture content, specific gravity, and void ratio are explained, serving as critical parameters for engineering analysis. The document outlines methods to assess the trạng thái đất (soil state) for both coarse-grained soils (using độ chặt indices) and fine-grained soils (via Atterberg limits). Furthermore, it introduces standardized phân loại đất systems like the USCS and TCVN. Finally, the text addresses peculiar soil phenomena highly relevant to geotechnical engineering, including tính co và nở (shrinkage and swelling), hiệu ứng Tiksotropi (thixotropy), and biến loãng cát (liquefaction of saturated sands), underscoring their practical implications for earthworks, foundation design, and overall geotechnical stability. This foundational knowledge is crucial for predicting soil response under various loading and environmental conditions, thereby ensuring safe and sustainable infrastructure development.