TBM surrounding rock classification method

Abstract

The invention relates to the field of tunnel engineering, and provides a TBM surrounding rock classification method in order to facilitate acquisition of evaluation indexes under a TBM working condition to realize rapid classification of surrounding rock, seismic wave velocity, tunneling parameters and rock slag content are adopted as surrounding rock classification evaluation indexes, and the three characteristics are convenient to acquire and high in accuracy. And the quality of the surrounding rock can be represented from the three aspects of rock, machine and slag, and rapid classification of the TBM construction surrounding rock is achieved.

Description

Technical Field

[0001] The invention relates to the field of tunnel engineering, and in particular to a TBM surrounding rock classification method. Background Art

[0002] Surrounding rock classification in tunnel construction is an important comprehensive indicator for evaluating the quality of surrounding rock mass. In the nearly 100 years of research, more than 100 classification methods have been proposed. Traditional surrounding rock classification methods (represented by BQ, HC, etc.) generally adopt a multi-factor method and score each single factor separately, and classify the surrounding rock in a certain way by summarizing and comprehensively evaluating. The indicators selected by this type of surrounding rock classification method are similar, and all contain basic lithology and structural information, joint and fissure information, and groundwater information. However, under the double shield TBM working conditions, the above information is difficult to collect effectively, or the collected information is seriously distorted. Therefore, this type of surrounding rock classification evaluation method is difficult to apply to TBM tunnels. The other type is the surrounding rock classification method represented by the evaluation of the working conditions of the tunnel boring machine. Specifically, it should be classified as the evaluation of the suitability of TBM tunneling, rather than the evaluation of the objective surrounding rock conditions. Therefore, it is particularly urgent to find a surrounding rock classification method suitable for TBM tunnel construction. Summary of the invention

[0003] In order to facilitate the collection of evaluation indicators to achieve surrounding rock classification under TBM working conditions, the present application provides a TBM surrounding rock classification method.

[0004] The technical solution adopted by the present invention to solve the above problems is: TBM surrounding rock classification methods include: Step 1, determining the factors for distinguishing surrounding rock classification, wherein the factors include excavation parameters, rock slag content and seismic wave velocity; Step 2: Establish a comprehensive classification model based on the discriminant factors. The comprehensive classification model is as follows: determine the surrounding rock classification level according to each discriminant factor respectively. If the surrounding rock classification levels determined by each discriminant factor are the same, then this classification level is the final level. If the surrounding rock level determined by a certain discriminant factor is different from that determined by the other two discriminant factors, then the final level is the surrounding rock level determined by the other two discriminant factors reduced by one level. Step 3: Install a seismic wave excitation and receiving device on the TBM, and install a slag screening device at the slag discharge position at the rear of the TBM; Step 4: Excite the seismic wave source during the TBM excavation process, and record the seismic wave velocity and excavation parameters of the rock mass in front of the tunnel face: penetration and thrust, and slag content; Step 5: Determine the surrounding rock classification based on the comprehensive classification model.

[0005] Furthermore, the slag content is specifically flaky slag content.

[0006] Furthermore, the tunneling parameter is specifically the penetration-thrust ratio.

[0007] Furthermore, the specific method for determining the surrounding rock classification level by each discriminant factor in the comprehensive classification model is as follows: When the penetration-thrust ratio is less than 0.3, it is Class II; when 0.3≤thrust ratio<0.8, it is Class III; when 0.8≤thrust ratio<1.4, it is Class IV; when 1.4≤thrust ratio, it is Class V; When the flaky rock content is greater than 75%, it is Class II; when the flaky rock content is 75 ≥ and greater than 50%, it is Class III; when the flaky rock content is 50 ≥ and greater than 10%, it is Class IV; when the flaky rock content is 10 ≥ and greater than 10%, it is Class V; When the seismic wave velocity is greater than 3800, it is Class II; when the seismic wave velocity is 3800≥ and greater than 3200, it is Class III; when the seismic wave velocity is 3200≥ and greater than 2500, it is Class IV; and when the seismic wave velocity is 2500≥, it is Class V.

[0008] Furthermore, in step 3, a seismic wave excitation and receiving device is installed on the TBM cutterhead.

[0009] Compared with the prior art, the present invention has the following beneficial effects: the present application adopts seismic wave velocity, excavation parameters and rock slag content as surrounding rock classification evaluation indicators. These three characteristics are not only easy to collect, but can also characterize the quality of surrounding rock from three aspects: rock, machine and slag, respectively, and can realize the rapid classification of surrounding rock in TBM construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a flow chart of the TBM surrounding rock classification method; Figure 2 is the distribution trend relationship between the content of flaky rock slag and the quality of rock mass; Figure 3 is the distribution trend relationship between the massive rock slag content and the rock mass quality; Figure 4 The distribution trend relationship between the content of rock fragments and the quality of rock mass; Figure 5 is the distribution trend relationship between rock powder content and rock mass quality; Figure 6 is the correlation curve between the content of flaky rock slag and the quality of rock mass; Figure 7 The excavation parameters and surrounding rock classification corresponding to pile numbers K8+900~K9+500; Figure 8 The excavation parameters and surrounding rock classification corresponding to pile numbers K11+000~K11+500; Fig. 9 The excavation parameters and surrounding rock classification corresponding to pile numbers K13+000~K13+500; Fig.10is the correlation between seismic wave velocity and rock mass quality. DETAILED DESCRIPTION

[0011] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0012] like Figure 1 As shown in the figure, the TBM surrounding rock classification method includes: Step 1: Determine the factors for classifying surrounding rock, wherein the factors include excavation parameters, rock slag content and seismic wave velocity.

[0013] Whether it is traditional surrounding rock classification or TBM construction surrounding rock classification, the core is the selection and influence of surrounding rock classification indicators. For TBM construction in a closed environment, traditional evaluation indicators are difficult to obtain. This application comprehensively analyzes the selection basis of various factors that characterize the quality of TBM construction surrounding rock from the three aspects of "rock-machine-slag" surrounding rock mass characteristics (seismic wave velocity), excavation parameters and slag conditions.

[0014] ① Rock slag According to the analysis of the characteristics of rock slag in TBM tunnel construction, the rock slag of intact rock mass is generally mainly in the form of flakes, the rock slag of fractured rock mass is significantly increased in the form of blocks, and the rock slag of broken rock mass is mainly in the form of fragments. Therefore, there is a certain correlation between the morphological characteristics of rock slag and the integrity and quality of the rock mass in macroscopic judgment.

[0015] like Figure 2-5 As shown in the figure, through the analysis of the trend relationship between rock mass quality and the content of different forms of slag, it is found that there is a certain positive correlation between rock mass quality and the content of flaky slag. For rock masses with better rock mass quality, the content of flaky slag is generally around 60-80%, and the corresponding flaky slag content of rock masses with poor rock mass quality is significantly reduced, generally below 10%; there is a certain negative correlation between rock mass quality and the content of block, fragment and rock powder slag. The corresponding content of block, fragment and rock powder slag for rock masses with better rock mass quality is low, and the corresponding content of block, fragment and rock powder slag for rock masses with poor rock mass quality increases sharply.

[0016] The correlation between the content of flaky slag and the quality of rock mass is fitted as follows: Figure 6 As shown, the correlation between rock mass quality and flaky slag content is the highest, and the reliability of the fitting curve can reach 0.906. Therefore, this embodiment uses flaky slag content to characterize the rock mass quality during TBM tunneling to obtain higher accuracy.

[0017] ② Excavation parameters Excavation parameters are generated during TBM excavation. While reflecting the current TBM status, they are closely related to the surrounding rock conditions and are important parameters for characterizing the quality of the tunnel surrounding rock mass.

[0018] Figure 7-9 The following are the excavation parameters and surrounding rock classification of a typical tunnel section. The light gray in the figure represents Class III surrounding rock, and the dark gray represents Class IV surrounding rock. The three excavation parameters of total thrust, penetration, and penetration-thrust ratio all change with the change of surrounding rock conditions. The penetration-thrust ratio, that is, the penetration under unit thrust, has a better correspondence with the surrounding rock conditions. When this value is less than the normal excavation value, it means that the surrounding rock conditions are good and excavation is difficult, reflecting the suitability of TBM excavation; and when this value is greater than the normal excavation value, the discreteness is large. Therefore, this embodiment uses the penetration-thrust ratio to characterize the quality of the surrounding rock mass during TBM excavation.

[0019] ③ Seismic wave velocity of surrounding rock mass The rock mass seismic wave velocity is the propagation speed of seismic waves in the rock mass, which can comprehensively reflect the characteristics of the rock mass structure and integrity. Fig.10 The figure shows that there is a linear relationship between the seismic wave velocity of the surrounding rock of a certain TBM tunnel and the rock mass quality score. When the fitting is y=0.0365x-78, the reliability of the fitting line can reach 0.66. At the same time, it can be seen from the analysis that when the wave velocity is greater than 2800m / s, the linear relationship is more consistent, while when the wave velocity is less than 2800m / s, the rock mass quality is poor and the corresponding relationship is weak. Analysis shows that this may be related to the large discreteness when the hole location is selected and the surrounding rock stability is poor. In general, the rock mass seismic wave velocity can still characterize the rock mass quality relatively well.

[0020] Step 2: Establish a comprehensive classification model based on the discriminant factors. The comprehensive classification model is as follows: determine the surrounding rock classification level according to each discriminant factor respectively. If the surrounding rock classification levels determined by each discriminant factor are the same, then this classification level is the final level. If the surrounding rock level determined by one discriminant factor is different from that determined by the other two discriminant factors, then the final level is the surrounding rock level determined by the other two discriminant factors reduced by one level.

[0021] Based on a large amount of data statistics, the comprehensive classification model of this embodiment is expressed in a table form as follows: Comprehensive classification table of three factors of surrounding rock in TBM construction

[0022] The surrounding rock classification in the above table starts from Class II. When an item is not in this class of surrounding rock, the surrounding rock classification is one level lower. Since Class I surrounding rock has good rock mass quality, complete structure, stable cave surrounding rock, and low excavation efficiency when using TBM excavation, it is necessary to analyze it in combination with specific circumstances. This type of surrounding rock is not included in the classification of this embodiment.

[0023] Step 3: Install a seismic wave excitation and receiving device on the TBM. In this embodiment, the seismic wave excitation and receiving device is arranged at the cutter head, and a slag screening device is installed at the slag discharge position at the rear of the TBM.

[0024] Step 4: After installation, start the TBM and excavate normally. During the TBM excavation process, stimulate the seismic wave source, record the seismic wave velocity of the rock mass in front of the face, the slag content, and the penetration and thrust during the excavation process; calculate the penetration-thrust ratio based on the penetration and thrust.

[0025] Step 5: Determine the surrounding rock classification based on the comprehensive classification model.

Claims

1. TBM surrounding rock classification method, characterized by: include: Step 1, determining the factors for distinguishing surrounding rock classification, wherein the factors include excavation parameters, rock slag content and seismic wave velocity; Step 2: Establish a comprehensive classification model based on the discriminant factors. The comprehensive classification model is as follows: determine the surrounding rock classification level according to each discriminant factor respectively. If the surrounding rock classification levels determined by each discriminant factor are the same, then this classification level is the final level. If the surrounding rock level determined by a certain discriminant factor is different from that determined by the other two discriminant factors, then the final level is the surrounding rock level determined by the other two discriminant factors reduced by one level. Step 3: Install a seismic wave excitation and receiving device on the TBM, and install a slag screening device at the slag discharge position at the rear of the TBM; Step 4: During the TBM excavation process, a seismic wave source is excited to record the seismic wave velocity of the rock mass in front of the tunnel face, excavation parameters: penetration and thrust, and rock slag content; Step 5: Determine the surrounding rock classification based on the comprehensive classification model.

2. The TBM surrounding rock classification method according to claim 1, characterized in that: The slag content is specifically the flaky slag content.

3. The TBM surrounding rock classification method according to claim 2, characterized in that: The excavation parameter is specifically the penetration-thrust ratio.

4. The TBM surrounding rock classification method according to claim 3, characterized in that: The specific method for determining the surrounding rock classification level by each discriminant factor in the comprehensive classification model is as follows: When the penetration-thrust ratio is less than 0.3, it is Class II; when 0.3≤thrust ratio<0.8, it is Class III; when 0.8≤thrust ratio<1.4, it is Class IV; when 1.4≤thrust ratio, it is Class V; When the flaky rock content is greater than 75%, it is Class II; when the flaky rock content is 75 ≥ and greater than 50%, it is Class III; when the flaky rock content is 50 ≥ and greater than 10%, it is Class IV; when the flaky rock content is 10 ≥ and greater than 10%, it is Class V; When the seismic wave velocity is greater than 3800, it is Class II; when the seismic wave velocity is 3800≥ and greater than 3200, it is Class III; when the seismic wave velocity is 3200≥ and greater than 2500, it is Class IV; and when the seismic wave velocity is 2500≥, it is Class V.

5. The TBM surrounding rock classification method according to any one of claims 1 to 4, characterized in that: In step 3, a seismic wave excitation and receiving device is installed on the TBM cutterhead.

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