Geological hazard investigation

Now the prevention and control of geological disasters has entered the practical stage. How to do this work? At present, it is a vivid situation in which a hundred flowers blossom and a hundred schools of thought contend. Based on the author's experience in this field for more than ten years, this paper briefly discusses this issue. The key link of geological disaster prevention and control is geological disaster investigation.

1. Practice field of geological science

First of all, talk about the position of geological disaster prevention in geological work. 1983 The author pointed out at the academic meeting of the annual meeting of the Geological Society of Henan Province that geological science has two practical fields. The first is to find treasure, which is the work that geological science has been doing since its formation, including solid mineral resources, liquid mineral resources and gas mineral resources; The second is disaster prevention, including three aspects: ① prevention of geological disasters induced by engineering activities, and design in engineering construction is disaster prevention measures; (2) The prevention and control of natural geological disasters has many contents; (3) Preventing and controlling environmental damage and deterioration is a chronic hazard, but it threatens human survival and needs to be prevented. With the development of human engineering economic activities, geological disasters are becoming more and more serious, and there is a trend of doubling. It is very important to know this, and we can take the initiative to prevent and reduce the losses caused by disasters. 1989 The author once put forward that "reducing disaster means increasing production", and only tangible increase in production, without intangible disaster prevention, was offset. Therefore, disaster prevention has great economic benefits. "Disaster reduction means increasing production". Disaster reduction is now attracting worldwide attention.

Principles of geological engineering

2. Definition of geological disasters

What is a geological disaster? There are different definitions. The definition given by the author is that geological events that cause loss of human life and property are geological disasters, and only geological events that do not cause loss of human life and property do not constitute geological disasters. Natural geological processes themselves are constantly developing, and geological events that cause loss of human life and property constitute geological disasters. Our task is to avoid the harm of geological disasters and minimize the losses caused by geological disasters through our work. To do this, we must first understand geological disasters. Only by understanding geological disasters can we prevent geological disasters, that is, only by understanding the world can we transform the world and prevent geological disasters. Geological hazard investigation is to understand geological hazards. If we don't do this work and control geological disasters, it is likely to get twice the result with half the effort.

3. Geological survey types and service objects

In order to understand geological disasters, we have carried out a large number of geological disasters investigations, discussed the formation law, mechanism and theory of geological disasters, and provided theoretical basis for identifying geological disasters. We should make full use of the basic theory and technology we have mastered to identify whether it is a geological disaster, its formation process, mechanism, harm and prevention plan. How do we carry out this series of work? The main means is geological disaster investigation. To understand geological disasters, it is necessary to carry out geological disaster investigation, but the current geological disaster investigation reports are various, many of which do not meet the requirements of geological disaster investigation. In order to understand the concept of geological disaster investigation, we must understand the types and contents of geological survey. In order to explain this problem concisely, it is summarized as table 14- 1.

Table 14- 1 Types and Contents of Geological Survey

The regional geological survey listed in table 14- 1 is also called regional geological survey. This work is to explore the regional laws of geological structures, and it must be carried out on the basis of understanding the development laws of regional geological structures in order to serve the planning, planned prospecting, planned engineering construction and planned land remediation. The purpose of mineral resources exploration is to find some mineral resources, evaluate their occurrence conditions, reserves and mining conditions, and serve industrial construction. Engineering geological survey is the most familiar work for engineering geologists. Its work content is to investigate engineering geological conditions, especially bad engineering geological conditions, to serve the planning, design and construction of engineering construction and to prevent man-made geological disasters caused by engineering construction. The geological disaster investigation proposed recently serves the prevention and control of geological disasters.

4. The basic contents of geological disaster investigation

The basic contents of geological disaster investigation include six types:

(1) Investigate the distribution scope and scale of geological disasters and pregnant bodies; Geological disasters have occurred, and their distribution scope and scale can be directly investigated. For those with precursors that haven't happened yet, we should make predictions. If they happen, how big the impact scope and scale may be, so as to prepare for disaster assessment and prediction.

(two) to investigate the geological disasters that have occurred, and to predict and evaluate the geological disasters that will occur;

(3) investigation and study on the causes of geological disasters, and prediction of the structure, movement mechanism and deformation trend (stability and influence range) of deformed bodies or disaster bodies;

(4) Study on the possibility of engineering governance (external dynamic action-treatable; Internal dynamic action-refractory period).

Principles of geological engineering

The author has seen some geological disaster investigation reports, especially those provided by geological departments, which are uncertain about disaster assessment and prediction. Some of them have done a lot, while others have done little. At present, there are still some methods to evaluate the stability of deformed bodies, but the scope of their influence in future disasters is not studied at present, which affects the investigation and prediction of disasters. Therefore, the scale and influence range of disasters is one of the important contents of geological disaster investigation. Disaster investigation and prediction evaluation are the main differences between geological disaster investigation and other types of geological exploration, and they are one of the important contents of geological disaster investigation. Without this disaster, it is hard to say whether it should be prevented. Disaster includes economic loss, social impact and environmental damage, which are usually called three major benefits. Disaster assessment should include these three aspects, which are unique in geological disaster investigation and must be done well.

The third aspect is the analysis of the conditions of pregnancy, the characteristics of pregnancy, the causes of disasters, the structure, movement mechanism and deformation trend prediction (stability and influence range) of deformed or disaster bodies. This is the core work of geological disaster investigation and a very important link in studying disaster prevention schemes. With these contents, we can study the possibility of engineering governance. The possibility of engineering control should be treated separately. For example, geological disasters induced by external forces, including human activities and geological external forces, can be controlled through engineering; Generally speaking, geological disasters caused by internal forces, such as fault activities and earthquakes, are difficult to control, and some are uncontrollable. We can take measures to prevent disasters, such as earthquakes, and hide, sometimes there is no way to hide. We can take seismic fortification to prevent disasters. Not all geological disasters caused by external dynamic action are to be treated or worthy of treatment. There are two disaster prevention schemes. One is to resist Tibet, strengthen projects and relocate residential areas. In this case, the economic and social benefits are generally low. Because of the large investment in governance, it is better to relocate and properly strengthen the project. For example, Dongdajing landslide in Yunyang County, Sichuan Province, the disaster situation is very serious, but the governance benefit is very low. Besides, when the Three Gorges Reservoir is completed in 2000, the village will be submerged. Obviously, relocation, refuge and project management mainly depend on prevention and control benefits. As mentioned above, the control benefits include economic benefits, social benefits and environmental benefits. Economic benefits are more specific and easier to demonstrate. Social interests are complex, involving politics and culture. For example, there is a Qiongjie county in Tibet, which is threatened by mudslides. The economic benefits of prevention and control are not great, but the social benefits are great. Many places of interest in Tibet are there, and the tomb where Songzan Gampo and Princess Wencheng were buried together is also there. Social benefits are very important, and this must be prevented. There are also environmental benefits, which are also very important. Comprehensive judgment is needed to determine whether treatment should be given.

Another investigation content is deformation monitoring. The author has talked about this problem many times, and his opinion is that this work should be carried out at the beginning of geological disaster investigation. It takes at least one year to investigate geological disasters. It is very valuable for us to use this year to monitor deformation, collect deformation data and evaluate the activity of disaster bodies or deformation bodies. In many cases, the calculation results are stable, but the observation results show that the cracks are still developing. For example, the stability of Lianziya dangerous rock mass, some calculated safety factors are 3.7, and some calculated safety factors are 1.7. No one has calculated that it is unstable, but the observation result is that the deformation continues to develop. The reason is that it is difficult to choose your calculation model and calculation parameters correctly. The calculation results can only be used for reference. What should I do? We should respect the monitoring results. Deformation is still developing, indicating instability. This conclusion is reliable, which shows that deformation monitoring is very important. The second importance of deformation monitoring is to monitor the safety of the construction process and prevent accidents in the construction process. The third important significance is to check the governance effect. Whether the governance is good or not depends on the actual effect of governance. The effect test is not a matter of one and a half years, and it needs to be tested for a period of time. For example, the deformation of the bean sprout shed landslide has been obviously reduced after treatment, but it is still moving weakly and is now rebounding. Is it the end of transformation? We must continue to observe it. After the treatment of Hancheng power plant was completed, it did not move, and then it moved. This problem should be paid attention to, which is the basic content of geological disaster investigation.

Let's talk about the contents of the geological disaster investigation report first. 1995, the author consulted six geological disaster investigation reports, and only one of them met the requirements because there was no standard. The author believes that the basic contents of the geological disaster investigation report can still be put forward, mainly including the following parts:

Part I: Expounding the process and history of geological disasters, and the results of disaster investigation, prediction and evaluation (direct and indirect losses, economic, social and environmental losses and damages);

Part II: Expounding the environmental geological conditions (meteorology, hydrology, geography, geology, etc.). ) is the formation of geological disasters;

The third part: the regional characteristics of geological disasters, the scale of possible geological disasters, the structure of disaster-prone bodies (deformed bodies), boundary conditions, physical and mechanical parameters, the causes of geological disasters, disaster-causing factors, deformation mechanism, stability analysis, movement process and influence range prediction;

The fourth part discusses the necessity of governance: analysis and demonstration according to the economic, social and environmental benefits of governance; Discuss the possibility of governance; Demonstrate the disaster prevention plan;

Part V: Conclusion.