(1) This standard is recommended as "recommended standard". As a "standard", it is different from a monograph and achievement, as long as the monograph and achievement have their scientific level. For a standard, it must have a certain maturity. This maturity does not lie in its framework, its guiding ideology, but in the maturity of the indicators of the grades it stipulates. Now it is very enough for you to demonstrate with the information you have collected. Professor Lin's argument on the basis of the proposed formula makes people feel full. But the rock mass is very complicated. You used many examples in your argument, but whether the rock mass type you chose is comprehensive enough, whether you have collected enough engineering types, and then connecting a series of problems such as the scale of the project, you can see that this problem is very complicated and a big one. I'm not saying that you collect less data, but that there were no standards to guide your work in the past. As a result, the content of data accumulated in existing projects is very different, and there is not much available data. You collected more than 500 data, only 103, which fully illustrates this problem. In other words, the data obtained at present show that the maturity of this standard is not enough. In terms of maturity, I still feel a little lacking. The deficiency is that these indicators are still lack of practical test. So I think it's better to be a recommendation standard from a big perspective. As a mandatory "standard" of a country, it may cause trouble because it is not mature enough at once. I feel that the maturity has not been tested. This is my first opinion.
(2) Definition of structural plane. A very important feature of rock mass is its discontinuity, which is caused by the cutting of various structural planes. Here's a problem. The definition of structural plane is given in the appendix. This definition is very important, because if you define it this way, you have to follow the definition. We must distinguish between geological interface and structural plane. All joints and fractures, whether cemented or not, are geological interfaces, but not all structural planes. Structural plane refers to the geological interface that is not cemented, cracked or easy to crack. Strictly speaking, it is the discontinuity of strength. It is very important that cemented joints and cracks do not belong to structural planes. The definition of structural plane is very important. I suggest you modify the definition of structural plane. Your definition is "structural plane refers to a mechanical discontinuous geological interface with a certain orientation, a certain shape, a certain scale and characteristics, including bedding planes, joints and faults." In the history of geological development. I suggest that it be amended as: "Structural plane refers to the fractured, easily fractured and mechanically discontinuous geological interface with a certain orientation, a certain shape, a certain scale and characteristics formed in the history of geological development, including bedding plane, joints and faults". It is very important to add the words "cracking and easy to crack", which is the main symbol of structural plane I talked about in rock mass mechanics. Without the description of these words, it cannot be called structural plane. According to this definition, it is a bit inappropriate to look at the primary and secondary arrangement method of elements used in rock mass integrity division in Table 3.3. 1. I think the first two should be placed in one position, that is, the "combination degree of main structural planes" should be placed in front of the "development degree of structural planes", that is to say, those geological interfaces with good cementation will not be treated as structural planes, and those without cementation will be treated as structural planes. This is an important basis for the concept of structural plane. On this basis, the degree of combination is divided. The combination you use includes cementation and cementation. This is not right. I think it should refer to the degree of false cementation and unconsolidation. On this basis, it is better to divide the integrity of rock mass by the development degree of structural plane. It is very important to identify structural planes, but some people often make mistakes and treat geological interfaces and structural planes equally. Cemented joint surface can not be called structural surface, and geological interface and structural surface can not be confused. Therefore, I suggest that the first two elements in Table 3.3. 1 should be changed, and the degree of cementation should be considered first. If the geological interface is cracked, it is very important for us to consider the development degree of structural plane. Please think about this problem. There is another problem here, that is, the scale of structural plane. Can joints and faults be treated equally? In your report this morning, there is a table (Figure 4 on page 9 of the National Standard for Classification of Engineering Rock Mass), which contains joints and small faults. What scale faults can you include in your standard classification? The main types of structural planes proposed in Figure 4 on page 9 of the report include: joint cracks, structural joints, minor faults and structural fractures. This is serious, including structural fractures. Structural fracture cannot be expressed by the degree of cracking. Different structural planes have different mechanical functions. The mechanical function of small-scale structural plane is mainly to weaken the mechanical properties of rock mass. When the width of large structural plane is more than 20 ~ 30cm, it will not only weaken the mechanical properties of rock mass, but also form a weak structural plane alone, which is easy to induce collapse under its cutting. This special mechanical action must be distinguished. At present, the structural planes used for engineering rock mass classification or classification mainly refer to low-order and small-scale structural planes. These low-order and small-scale structural planes cut rock mass into different degrees of fragmentation. However, high-order and weak structural planes cannot be considered. My experience in tunnel work is that when I meet a structural plane with a width greater than 30cm, it will collapse. Obviously, its function is not only to cut, but also to collapse together or alone with smaller structural planes around it. No matter how many joints there are, landslides will not occur under high stress conditions; However, the geostress of weak structural plane with width greater than 30cm has no transformation effect on it. In particular, the weak structural plane can be combined with the upward growing hard structural plane to form a wedge-shaped block, thus forming a block collapse. This is the most common type of landslide in underground engineering construction.
(3) Explain that "this standard is applicable to rock mass quality evaluation of low-order structural plane cutting". The order and scale of structural planes must be divided. Dividing high-order and weak structural planes does not participate in rock mass quality classification. For those high-order weak structural planes, block combination and block stability analysis should be carried out. This type should be treated specially and should not be included in the rock mass quality grading standard. Therefore, I suggest that Article 2 of the General Rules "This standard is applicable to rock mass classification of all kinds of rock engineering" be amended as "This standard is applicable to the classification of rock mass quality standards cut by low-order structural planes, and the stability evaluation of blocks cut by high-order and weak structural planes or themselves should be specially studied". It should also be emphasized that a large fault zone with a width exceeding 30cm will also cause landslides, which cannot be equated with ordinary joints. This Standard is only applicable to the quality evaluation of rock mass cut by structural planes less than a few centimeters or more than ten centimeters, and is not applicable to large-scale high-order weak structural planes with widths greater than 20 and 30cm. You can change the second article of this standard, that is, article 65438 +0.0.2, which will be better used. When encountering a small fault with a width greater than 20cm, warn the user not to treat it like an ordinary joint. I believe that the coincidence rate between this standard and the actual situation can be greatly improved. The revision of this article is very important. This revision did not reduce the reputation of this standard, but improved the quality of this standard. At the same time, it tells users that when they encounter high-order large and weak structural planes, they cannot be simply treated as low-order. In addition to the general rock mass quality evaluation, the stability of composite blocks and fault zones should also be analyzed to ensure the stability evaluation of rock mass. As for how to divide the boundary between high-order sequence and low-order sequence, structural planes with a width less than 30cm can be classified by the number of structural planes, and weak structural planes with a width greater than 5cm should all be included in the block combination analysis. When the width of structural plane is more than 30cm, the stability of fault zone should be analyzed to make the results more reliable. A few years ago, I drilled many holes in water conservancy and hydropower, mines, railways, national defense, industrial and civil buildings, which gave me a prominent impression that the biggest probability of collapse was the collapse of blocks and fault zones themselves. Some caves are granite, and there is no deformation in them, but they collapse when they meet the intersection of faults, and the caves are buried and all scrapped. The problem lies in the fault zone. Therefore, I suggest that this problem be specifically explained, and it should be made clear in the general rules that it is not applicable to all kinds of projects, but more importantly, what kind of rock mass is suitable for cutting structural planes.
(4)Rc and Kv are product relations. In order to choose the "BQ" formula, you have dealt with so many combinations. Have you made another combination, that is, the product of Rc (rock strength) and Kv (fracture degree), then it can be written as:
Principles of geological engineering
The form of. Why? Because the function of Kv is to attenuate the strength of rocks. Rock strength can be high, but there are cracks in it, so the strength can be attenuated, so I think these two indicators are multiplied, not added. Addition is ok, but it is not suitable for two reasons. One is that the mechanism of action is inconsistent; The other is that it doesn't work in dimensions. The treatment of statistical formulas can not be considered purely mathematically, but more importantly, it should be considered from the mechanism and dimension combination. Please reconsider the problem.
(5) Low geostress problem. In the fourth chapter, you talked about the correction of in-situ stress and groundwater factors. This is an improvement on the classification or grading of surrounding rocks. I have no problem with the correction of groundwater factors. My view on geostress correction is that you emphasize the correction of high geostress in geostress correction, which is correct. However, during the construction of Jundushan Tunnel from 1986 to 1989, I found that Jundushan is located in the Yanshan fold belt, which should be a high stress area, but the landslide is so serious. Why is this? Professor Yang Zhifa used the deformation monitoring results to carry out back analysis of in-situ stress. The analysis results show that the lateral pressure coefficient is only 0. 1, that is, the lateral stress is only 10% of the maximum (vertical) principal stress, which is less than half of the elastic lateral expansion coefficient ξ. This shows that this area is a low geostress area. In this way, I understand that the lateral stress is small, and of course the landslide is serious. Obviously, low geostress is also a big problem. The correct understanding should be to divide the geostress into three grades, namely, high geostress zone, medium geostress zone and low geostress zone. The main geological disasters of underground engineering buildings in high stress areas are rockburst, spalling, plate cracking and plastic convergence deformation. The main geological disasters of underground engineering buildings in low geostress areas are landslides and water inrush, which are more harmful than those in high geostress areas. In this area, landslides may collapse to the top of the cave. Jundushan Tunnel is a good example. I only knew the landslide before, but I didn't know the reason, so I said it was very important to know the fact of low geostress. Now I put more emphasis on low geostress. I specifically talked about the problem of low geostress in Engineering Geology and Geological Engineering published this year, and also gave the geological signs of low geostress areas. It is hoped that full attention will be paid to the problem of low geostress in this standard. I suggest that the standard of division can be based on the lateral stress coefficient of self-weight. If it is greater than it, it is medium geostress, if it is less than it, it is low geostress area. Please study it. This problem is very prominent in underground engineering, but not very big in surface engineering. Therefore, I hope that the geological indicators in low geostress areas can be added to the standard, and I can refer to the contents of my book Engineering Geology and Geological Engineering. It is very important to divide the geostress into three grades. There are special problems in underground engineering buildings in high and low geostress areas, and the medium geostress area is better.
(6) This standard should be regarded as the basic standard of rock mass quality classification, and it does not involve practical classification standards of various projects for the time being. I quite agree with you that the basic quality classification standard of rock mass is given in the Classification Standard of Rock Mass at first, but it will not be classified for all kinds of engineering rock mass for the time being, because there are many factors related to rock mass stability for specific projects. If we talk about this here, it doesn't mean anything. It is best not to talk about it. For example, underground engineering, ranging from a small hole to an underground space group, spans tens of meters to hundreds of meters, and high side walls range from tens of meters to hundreds of meters. It is incomprehensible to explain only a few. At present, in the general classification, the size of the monorail tunnel, that is, 5m, is used as the standard to determine the classification standard. Therefore, it is necessary to make a special study on the double-track tunnel. Because the space of the double-track tunnel reaches 10m, the blocks cut by the weak structural plane in the space of 10m have more chances to collapse, so the stability cannot be simply evaluated by the quality standard. Because the blocks cut by weak structural plane play a role in it, especially in underground engineering, self-weight and in-situ stress play a role, and it is easy to collapse when the local stress is low; Different from dam foundation, gravity in dam foundation has a good effect on the stability of rock mass, and only weak structural plane with gentle dip angle can be unstable under the push of horizontal force. The problem of high-rise buildings is even less serious, and its horizontal thrust is very small. Therefore, my opinion is that this standard does not mention the classification of rock mass quality of various projects, and it may be more appropriate to take geostress and groundwater as the revised contents of rock mass quality evaluation and formulate some general revision methods into this standard. In this standard, you use the method of coefficient correction to correct geostress and groundwater, which may be more accurate than the method of degradation. This method is an improvement. I agree to use the correction coefficient to correct the influence of in-situ stress and groundwater factors on the basic quality of rock mass. It is wise not to consider the project here for the time being. At present, there are many experiences in underground engineering, but few experiences in rock mass quality classification in surface engineering. Although the research on rock mass quality of dam foundation has been very detailed at present, it can not be put forward as a grading standard of rock mass quality. For example, in-situ stress is not considered in dam foundation, but actually should be considered. For any engineering evaluation of rock mass quality, the ground stress groundwater should be corrected, but for underground engineering, the size of the project should also be considered, and the slope height is also a very important factor. There are many engineering factors, only a few of which are difficult to explain in this standard. It may be better to leave this issue to professional standards. I suggest that the title of Chapter 4 should be changed to "Environmental factor correction of engineering rock mass classification".
There is one small problem. I appreciate your innovative spirit. It is good to change classification into classification. The concept of basic quality of rock mass is put forward, and the quality coefficient (Q) of rock mass is given. However, there are contradictions in this standard. Why do the words "rock engineering" and "rock mass classification" appear in this standard? I suggest that it is better to change "rock engineering" into "rock mass engineering".
Generally speaking, I think this standard is well compiled, with clear thinking, reliable theoretical basis and high quality. It can be issued and implemented as a recommended standard, and it is appropriate to summarize the experience and further revise it in the implementation, and then issue and implement it as a mandatory standard.