The main contents of engineering geology research include: determining the composition, microstructure, physical, chemical and mechanical properties (especially strength and strain) of geotechnical engineering and its influence on the stability of building engineering, classifying geotechnical engineering geology, and putting forward methods to improve the performance of geotechnical engineering buildings; Study the natural environment balance destroyed by human engineering activities, the hazards of natural physical and geological processes such as collapse, landslide, debris flow and earthquake to engineering buildings, and their prediction, evaluation and prevention measures; Study and solve the foundation stability in various engineering buildings such as slopes, subgrade, dam foundation, piers and caves, as well as the collapse of loess and the destruction of rock cracks, and formulate a set of scientific investigation procedures, methods and means to directly provide geological basis for the design and construction of various projects; Study the movement law of groundwater in construction site and its influence on engineering buildings, and formulate necessary utilization and protection schemes; Study the characteristics of regional engineering geological conditions, predict the changes caused by human engineering activities, evaluate regional stability, and carry out engineering geological zoning and mapping. With the development of large-scale engineering construction, its research field is expanding day by day. In addition to geotechnical and engineering dynamic geology, specialized engineering geology and regional engineering geology, some new sub-disciplines are gradually forming, such as mine engineering geology, marine engineering geology, urban engineering geology and environmental engineering geology, engineering seismology and so on.

1 Difference between engineering geology and geotechnical engineering

Engineering Geology is a science that studies geological problems related to engineering construction (Zhang et al., China Engineering Geology). Engineering geology has a strong application. The planning, design, construction and operation of all kinds of projects should be well studied in engineering geology, so that the engineering and geology can coordinate with each other, which not only ensures the safety, reliability, economic rationality and normal operation of the project, but also ensures that the geological environment will not deteriorate due to the construction of the project and cause harm to the project itself or the geological environment. The contents of engineering geology research include: soil engineering geology research, rock engineering geology research, engineering dynamic geological function and geological disaster research, engineering geological exploration theory and technical method research, regional engineering geology research, environmental engineering geology research and so on.

Geotechnical engineering is a science and technology involving the utilization, treatment or improvement of rocks and soil in civil engineering (national standard "Basic Terminology Standard of Geotechnical Engineering"). The theoretical basis of geotechnical engineering is mainly engineering geology, rock mechanics and soil mechanics; The research content involves many aspects such as engineering carrier, engineering load, engineering materials, conductive medium or environmental medium. Including geotechnical engineering survey, design, construction, testing and monitoring.

It can be seen that engineering geology is a branch of geology and its essence is an applied science. Geotechnical engineering is a branch of civil engineering, and its essence is an engineering technology. Geological experts (geologists) are engaged in engineering geology, focusing on geological phenomena, geological causes and evolution, geological laws and the interaction between geology and engineering; Engineers are engaged in geotechnical engineering, and they are concerned about how to build a project or part of a project that meets the use requirements and safety requirements according to the engineering objectives and geological conditions, and solve geotechnical technical problems in engineering construction.

2 the relationship between engineering geology and geotechnical engineering

Although engineering geology and geotechnical engineering belong to both geology and civil engineering, it goes without saying that they are closely related. Some people say that engineering geology is the foundation of geotechnical engineering, and geotechnical engineering is the extension of engineering geology, which makes sense.

Engineering geology originates from the needs of civil engineering, and geotechnical engineering, as a branch of civil engineering, is developed on the basis of traditional mechanical theory. But simple mechanical calculation can't solve practical problems, and it has an indissoluble bond with engineering geology from the beginning. Compared with structural engineering, structural engineering is faced with artificial materials such as concrete and steel, which are relatively unified, and the materials and structures are selected or designed by engineers themselves and controllable. The calculation conditions are very clear, so the calculation based on material mechanics and structural mechanics is credible. However, geotechnical materials, both in performance and structure, are naturally formed and are the products of long geological history and various complex geological processes. Engineers can't choose and control their own materials and structures at will, but they can only understand them through investigation, and in fact they can't fully understand them. Geotechnical engineers can't trust simple calculation results, and simple calculation is unreliable. The reason lies in the uncertainty of engineering geological conditions and geotechnical parameters, the fuzziness of calculation conditions and the incompleteness of information to varying degrees. Therefore, although soil mechanics, rock mechanics and calculation technology have made great progress and played an important role in geotechnical engineering design, there are many inconsistencies between calculation assumptions, calculation modes, calculation methods and calculation parameters and the actual situation, and the calculation results are always quite different from the actual situation, which requires comprehensive judgment.