Alteration rock tunnel excavation risk index calculation and risk identification method

Abstract

The invention discloses an alteration rock tunnel excavation risk index calculation and risk identification method, and aims at solving the problems that clay alteration rock tunnel excavation disasters caused by the combined action of a long-term structure and a hydrothermal solution frequently occur, and risk identification and disaster prevention and control are difficult. Therefore, altered rocks are divided into a rock vein type and a full-section type according to tunnel surrounding rock characteristics. Aiming at the rock vein type, providing a rock vein type excavation risk index calculation and risk grading method based on alteration zone spatial occurrence, width density, an included angle with the axial direction of a tunnel and underground water development characteristics; the overall alteration degree is calculated based on the rock powder plasticity index and the fine grain weight percentage content after altered rock is fully disintegrated when meeting water for a full-section type, and the risk index calculation and risk grading method of the full-section type is provided by combining the crushing degree of surrounding rock and the development characteristics of underground water. And a scientific basis is provided for clay altered rock tunnel excavation risk identification and prevention and control.

Description

Technical Field

[0001] The invention relates to the technical field of preventing rock collapse, and in particular to a method for calculating a risk index of altered rock tunnel excavation and identifying the risk. Background Art

[0002] Strong tectonic activities and hydrothermal effects have given birth to many deep clay-altered rock belts [1-3], resulting in frequent disasters of different types, degrees and ranges during tunnel construction. Clay-altered rocks are the product of long-term tectonic compression and hydrothermal replacement. Their mineral composition and microstructure have undergone significant changes under the influence of internal and external dynamic geological effects such as late diagenetic tectonic, hydrothermal and superficial transformation.

[0003] Under the dual effects of physics and chemistry, most altered rock masses have loose structures, developed cracks, low strength, poor stability, and are rich in viscous minerals such as kaolin, montmorillonite, and chlorite, which are very easy to absorb water, soften, and disintegrate. Therefore, during the excavation of long and deep-buried tunnels in clay-altered rock, engineering problems such as large soft rock deformation, landslides, water and mud inrush occur to varying degrees. The larger the cross-section, the higher the ground stress, and the more abundant the groundwater, the higher the difficulty and engineering risk of underground engineering excavation.

[0004] The alteration index can effectively reflect the impact of alteration on rock mass strength, help to subdivide clay-altered rock mass, and effectively carry out risk assessment and prevention of altered rock mass excavation. "Shear deformation failure characteristics and statistical damage model of medium-altered structural surface" (Ding Xiuli, Liu Tongling, Huang Shuling, etc.) used CIA to evaluate the alteration of the structural surface in the underground powerhouse area of ​​Fengning Pumped Storage Power Station in Hebei Province, but the CIA measurement cost is relatively high.

[0005] In the book Research on Engineering Classification and Physical and Mechanical Properties of Altered Rocks (Dong Jinyu, Shi Shang, Li Jianyong, etc.), the mass percentage of clay minerals in the XRD test of altered rocks was defined as the alteration index, and the relationship between the alteration index and the macroscopic mechanical properties and microscopic pore development characteristics was studied. However, XRD testing is also expensive and time-consuming, which is not conducive to on-site promotion.

[0006] In "Study on the Development Law and Engineering Properties of Altered Rocks" (Pan Xuwei), referring to the Hoek_Brown criterion, short-wave infrared spectroscopy (SWIR) was used for rapid identification of altered rocks on site, and the rock alteration geological intensity index AGIS was proposed. However, the current alteration indexes all start from the altered mineral content, which makes it difficult to grasp the overall impact of alteration on the rock as a whole and to effectively reflect its engineering properties. Summary of the invention

[0007] In view of the shortcomings of the existing technology, the present invention proposes a method for calculating the risk index of altered rock tunnel excavation and identifying the risk, which can effectively evaluate the development risk of altered rock tunnel. The specific technical solution is as follows:

[0008] According to the characteristics of tunnel surrounding rock, altered rock is divided into two types: vein type and full section type; the full section type altered rock mass is broken and loose, with severe clay alteration, no obvious dominant structural surface, and the exposed surrounding rock shows obvious sandification and mudification. The vein type is usually associated with structural structural surfaces or basic intrusive veins, with a small scale (width ranging from 0.1 to 5m), and the rock blocks are easy to slide along the structural surface.

[0009] In a first aspect, a method for calculating the risk index of full-section altered rock tunnel excavation is provided. In a first achievable manner of the first aspect, the method comprises: obtaining the rock powder plasticity index and fine particle weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area;

[0010] The overall alteration degree of the full-section altered rock is calculated based on the rock powder plasticity index and the percentage of fine particle weight. The specific calculation formula is as follows:

[0011]

[0012] Among them, GAI is the overall alteration degree, α is the clay plasticity index, IP is the rock powder plasticity index, and λ is the percentage of fine particle weight;

[0013] Determine the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock respectively according to the overall alteration degree, surrounding rock block size and groundwater development characteristics;

[0014] The excavation risk index of the full-section altered rock is calculated by combining the overall alteration risk index, block risk index and groundwater development risk index.

[0015] In combination with the first implementable manner of the first aspect, in a second implementable manner of the first aspect, obtaining the rock powder plasticity index of the full-section altered rock in the tunnel excavation area after full disintegration includes:

[0016] Testing the liquid limit and plastic limit of rock powder after the full-section altered rock is fully disintegrated;

[0017] The rock powder plasticity index is calculated based on the liquid limit and plastic limit of the rock powder.

[0018] In combination with the first implementable manner of the first aspect, in a third implementable manner of the first aspect, the specific calculation formula of the excavation risk index of the full-section altered rock is as follows:

[0019] R=A 1 A 2 η;

[0020] Among them, A 1is the overall alteration risk index, A 2 is the block risk index, and η is the groundwater development risk index.

[0021] In a second aspect, a method for calculating a risk index of clay-altered rock tunnel excavation is provided. In a first achievable manner of the second aspect, the method includes: determining the altered rock type to which the clay-altered rock in the tunnel excavation area belongs;

[0022] Collect corresponding influencing factors according to the altered rock type, and calculate the excavation risk index of the clay-altered rock tunnel;

[0023] When the altered rock type is a full-section type, the excavation risk index of the clay-altered rock tunnel is calculated by using the full-section altered rock tunnel excavation risk index calculation method as described in any one of the first to third achievable methods of the first aspect.

[0024] In combination with the first implementable manner of the second aspect, in a second implementable manner of the second aspect,

[0025] When the altered rock is a vein-type altered rock, the spatial occurrence, vein width, number of veins, axial angle of the vein relative to the tunnel and groundwater development characteristics of the altered vein are obtained;

[0026] The risk index of altered dyke type occurrence is determined based on the axial angle and spatial occurrence; the risk index of dyke width density is determined based on the dyke width and number of dykes; and the risk index of groundwater development is determined based on the groundwater development characteristics;

[0027] Calculate the excavation risk index of the clay-altered rock tunnel according to the vein type occurrence risk index, vein width density risk index and groundwater development risk index;

[0028] R 2 =D 1 D 2 D 3 η;

[0029] Among them, R 2 is the excavation risk index of dyke-type altered rock, D 1 is the risk index of the vein-type altered rock, D 2 is the risk index of vein width density of vein-type altered rocks, D 3 It is the clay alteration index.

[0030] In a third aspect, a method for identifying risks in tunnel excavation in clay-altered rock is provided, which is characterized by comprising:

[0031] The excavation risk index of the clay-altered rock tunnel is calculated by using the clay-altered rock tunnel excavation risk index calculation method described in the second aspect;

[0032] The risk level and risk type of clay-altered rock tunnel excavation are determined based on the excavation risk index.

[0033] In a fourth aspect, a full-section altered rock tunnel excavation risk index calculation system is provided, comprising:

[0034] The influencing factor acquisition module is configured to obtain the rock powder plasticity index and fine particle weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area;

[0035] The alteration degree calculation module is configured to calculate the overall alteration degree of the full-section altered rock according to the rock powder plasticity index and the fine particle weight percentage. The specific calculation formula is as follows:

[0036]

[0037] Among them, GAI is the overall alteration degree, α is the clay plasticity index, IP is the rock powder plasticity index, and λ is the percentage of fine particle weight;

[0038] A risk index determination module is configured to respectively determine the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock according to the overall alteration degree, surrounding rock block size and groundwater development characteristics;

[0039] The excavation risk index calculation module is configured to calculate the excavation risk index of the full-section altered rock by combining the overall alteration risk index, the block risk index and the groundwater development risk index.

[0040] In a fourth aspect, a risk index calculation system for clay-altered rock tunnel excavation is provided, comprising:

[0041] a type analysis module configured to determine the altered rock type to which the clay-altered altered rock in the tunnel excavation area belongs;

[0042] A risk index module, configured to collect corresponding influencing factors according to the altered rock type and calculate the excavation risk index of the clay-altered rock tunnel;

[0043] When the altered rock is a vein-type altered rock, the spatial occurrence, vein width, number of veins, axial angle of the vein relative to the tunnel and groundwater development characteristics of the altered vein are obtained;

[0044] The risk index of altered dyke type occurrence is determined based on the axial angle and spatial occurrence; the risk index of dyke width density is determined based on the dyke width and number of dykes; and the risk index of groundwater development is determined based on the groundwater development characteristics;

[0045] Calculate the excavation risk index of the clay-altered rock tunnel according to the vein type occurrence risk index, vein width density risk index and groundwater development risk index;

[0046] R 2 =D 1 D 2 D 3 η;

[0047] The excavation risk identification module is configured to determine the risk level and risk type of clay-altered rock tunnel excavation according to the excavation risk index.

[0048] Beneficial effect: By adopting the method for calculating the risk index and identifying the risk of altered rock tunnel excavation of the present invention, the overall alteration degree of the altered rock can be obtained by analyzing the particle size of the product after the surrounding rock is fully hydrolyzed. The overall alteration degree can quantitatively characterize the impact of the alteration on the entire surrounding rock, and better reflect the engineering characteristics of the altered rock. Combined with the groundwater development characteristics and the scale of the surrounding rock blocks, the development risk and risk type of the altered rock tunnel can be effectively evaluated, providing a scientific basis for the risk identification and prevention and control of clay-altered rock tunnel excavation. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] In order to more clearly illustrate the specific implementation of the present invention, the following will briefly introduce the drawings required for use in the specific implementation. In all the drawings, each element or part is not necessarily drawn according to the actual scale.

[0050] Figure 1 A flow chart of a method for identifying risks in tunnel excavation in clay-altered rock provided in one embodiment of the present invention;

[0051] Figure 2 A system block diagram of a full-section altered rock tunnel excavation risk index calculation system provided by an embodiment of the present invention;

[0052] Figure 3 A system block diagram of a clay-altered rock tunnel excavation risk index calculation system provided by an embodiment of the present invention;

[0053] Figure 4 A system block diagram of a clay-altered rock tunnel excavation risk identification system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0054] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0055] It should be understood that the inventors conducted statistical analysis on a large number of clay-altered rock excavation cases and ultimately classified the altered rocks into two types: vein type and full-section type according to the characteristics of the tunnel surrounding rock.

[0056] Embodiment 1

[0057] like Figure 1 As shown, a method for calculating the risk index of full-section altered rock tunnel excavation includes:

[0058] Step 1: Obtain the rock powder plasticity index and fine particle weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area;

[0059] Step 2: Calculate the overall alteration degree of the full-section altered rock according to the rock powder plasticity index and the fine particle weight percentage. The specific calculation formula is as follows:

[0060]

[0061] Among them, GAI is the overall alteration degree, α is the clay plasticity index, IP is the rock powder plasticity index, and λ is the percentage of fine particle weight. The overall alteration degree can characterize the overall alteration level of the surrounding rock, and the measurement cycle is short and the cost is low, which is convenient for promotion in engineering sites.

[0062] Step 3, determining the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock respectively according to the overall alteration degree, surrounding rock block size and groundwater development characteristics;

[0063] Step 4: Calculate the excavation risk index of the full-section altered rock by combining the overall alteration risk index, block risk index and groundwater development risk index.

[0064] Specifically, first, the surrounding rock block size and groundwater development characteristics of the full-section altered rock can be obtained. And select local surrounding rock samples of the full-section altered rock in the excavation area. Soak the surrounding rock samples in water for a long time. After the surrounding rock is fully disintegrated, the disintegrated products of the surrounding rock samples are screened to obtain the weight percentage of rock blocks with different particle sizes, so as to determine the fine particle weight percentage. In this embodiment, the disintegration products with a particle size of less than 0.1 mm can be defined as rock powder, that is, fine particles, those between 0.1 mm and 30 mm are defined as rock chips, and those above 30 mm are defined as rock blocks.

[0065] It should be understood that rock powder includes altered clay minerals and surrounding non-clay minerals affected by them, and can therefore effectively represent the degradation of the rock mass by alteration. Therefore, the rock powder plasticity index can be obtained by performing liquid limit and plastic limit tests on the screened rock powder. Then, the overall alteration degree of the full-section altered rock can be calculated using the above calculation formula based on the rock powder plasticity index and the percentage of fine particle weight. Afterwards, the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock can be determined based on the overall alteration degree of the full-section altered rock, the block size of the surrounding rock and the groundwater development characteristics.

[0066] Finally, the excavation risk index of the altered rock of the entire section can be calculated by combining the overall alteration risk index, block risk index and groundwater development risk index. The specific calculation formula is as follows:

[0067] R 1 =A 1 A 2 η;

[0068] Among them, R 1 is the excavation risk index of the full-section altered rock, A 1 is the overall alteration risk index of the altered rock in the entire section, A 2 is the block risk index of the altered rock in the whole section, and η is the groundwater development risk index of the altered rock in the whole section.

[0069] In this embodiment, the overall alteration risk index of the entire section altered rock can be determined according to the overall alteration degree through the following Table 1:

[0070] GAI Risk Index 20 1.2 20-50 1.6 >50 1.8

[0071] Table 1

[0072] The block risk index of the full-section altered rock can be determined according to the block size of the surrounding rock, that is, the degree of fragmentation of the surrounding rock, through the following Table 2:

[0073] Degree of damage Risk Index Chimerism 1.2 Shatter 1.6 Bulk 1.8

[0074] Table 2

[0075] According to the groundwater development characteristics, the groundwater development risk index of the full-section altered rock can be determined through the following Table 3:

[0076] Groundwater development characteristics Groundwater development risk index Dry without basement 1 Wet, small amount of drops 1.1 Drop-shaped 1.2 strands 1.4

[0077] Table 3

[0078] In this embodiment, optionally, in step 1, obtaining the rock powder plasticity index of the full-section altered rock in the tunnel excavation area after full disintegration includes:

[0079] Testing the liquid limit and plastic limit of rock powder after the full-section altered rock is fully disintegrated;

[0080] The rock powder plasticity index is calculated based on the liquid limit and plastic limit of the rock powder.

[0081] Specifically, when obtaining the rock powder plasticity index, the liquid limit and plastic limit test can be used to obtain the critical water content of the rock powder formed after the surrounding rock sample is fully disintegrated, which changes from a plastic state to a flowing state, that is, the liquid limit, and the critical water content of the rock powder transitioning from a plastic state to a semi-solid state, that is, the plastic limit. Finally, the rock powder plasticity index can be calculated based on the liquid limit and plastic limit. The specific calculation formula is as follows:

[0082] IP=ω L -ω P ;

[0083] Among them, ω L is the liquid limit, ω P For plastic limit.

[0084] Embodiment 2

[0085] like Figure 1 As shown, a method for calculating the risk index of clay-altered rock tunnel excavation includes:

[0086] Step S1, determining the altered rock type to which the clay-altered rock in the tunnel excavation area belongs;

[0087] Step S2, collecting corresponding influencing factors according to the altered rock type, and calculating the excavation risk index of the clay-altered rock tunnel;

[0088] When the altered rock type is a full-section type, the above-mentioned full-section altered rock tunnel excavation risk index calculation method is used to calculate the excavation risk index of the clay-altered altered rock tunnel.

[0089] Specifically, first, the altered rock type to which the altered rock belongs can be determined based on the surrounding rock characteristics during the excavation process. Among them, the lamellae-distributed layers in the vein-type altered rock have high clay mineral and pore contents. The surrounding rock of the full-section altered rock is loose and broken, the block size is diverse, and the water sensitivity is high. Then, based on the altered rock type to which the surrounding rock of the excavation area belongs, the corresponding influencing factors can be collected, and the excavation risk index of the excavation area can be calculated using the corresponding algorithm. When the surrounding rock of the excavation area belongs to the full-section altered rock, the calculation method described in Example 1 can be used to calculate the excavation risk index of the excavation area, providing a scientific basis for the identification and prevention of the excavation risks of clay-altered rock tunnels.

[0090] In this embodiment, optionally, when the altered rock is a vein-type altered rock, the spatial occurrence of the altered vein, the vein width, the number of veins, the axial angle of the vein relative to the tunnel, and the groundwater development characteristics are obtained;

[0091] The risk index of altered dyke type occurrence is determined based on the axial angle and spatial occurrence; the risk index of dyke width density is determined based on the dyke width and number of dykes; and the risk index of groundwater development is determined based on the groundwater development characteristics;

[0092] According to the vein type occurrence risk index, vein width density risk index and groundwater development risk index, the excavation risk index of the clay-altered rock tunnel is calculated.

[0093] Specifically, when the surrounding rock of the excavation area is a vein-type altered rock, the width and number of veins in the excavation area, as well as the axial angle of the vein relative to the excavation tunnel and the groundwater development characteristics can be detected. Among them, the vein-type occurrence risk index of the surrounding rock can be determined according to the axial angle and spatial occurrence of the vein relative to the excavation tunnel through the following Table 4:

[0094]

[0095] Table 4

[0096] The vein width density risk index of the surrounding rock can also be determined according to the vein width and the number of veins through the following Table 5:

[0097]

[0098] Table 5

[0099] The groundwater development risk index of the surrounding rock can also be determined according to the groundwater development characteristics through Table 3 above.

[0100] Finally, the excavation risk index of the vein-type altered rock can be calculated based on the vein-type occurrence risk index, vein width density risk index and groundwater development risk index. The specific calculation formula is as follows:

[0101] R 2 =D 1 D 2 D 3 η;

[0102] Among them, R 2 is the excavation risk index of dyke-type altered rock, D 1 is the risk index of the vein-type altered rock, D 2 is the risk index of vein width density of vein-type altered rocks, D 3 is the clay alteration index, which can be set to 1.1.

[0103] Embodiment 3

[0104] like Figure 1 As shown, a method for identifying risks in tunnel excavation in clay-altered rock is provided, and the identification method comprises:

[0105] The excavation risk index of the clay-altered rock tunnel is calculated by using the above-mentioned clay-altered rock tunnel excavation risk index calculation method;

[0106] The risk level and risk type of clay-altered rock tunnel excavation are determined based on the excavation risk index.

[0107] Specifically, first, the excavation risk index of the surrounding rock of the excavation area can be calculated using the calculation method described in Example 2. Then, based on the calculated excavation risk index, the risk level and risk type of the excavation area can be determined through the corresponding risk level comparison table.

[0108] Among them, the risk level comparison table corresponding to the full-section altered rock is as follows:

[0109] Risk Level <![CDATA[Risk Index R 1 > Risk Type I <1 Large deformation II 1 Large deformation of soft rock III 1～2 Landslide / / Close-door landslide IV 2>3 Mud and water surge V >3 Large-scale mud and water outburst

[0110] Table 6

[0111] The risk level comparison table corresponding to vein-type altered rocks is as follows:

[0112]

[0113]

[0114] Table 7

[0115] By matching the risk index with the corresponding risk level comparison table, the excavation risk level and risk type of clay-altered rock tunnels can be determined, providing a scientific basis for the prevention and control of clay-altered rock tunnel excavation.

[0116] Embodiment 4

[0117] like Figure 2 The system block diagram of the full-section altered rock tunnel excavation risk index calculation system shown in FIG. 1 includes:

[0118] The influencing factor acquisition module is configured to obtain the rock powder plasticity index and fine particle weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area;

[0119] The alteration degree calculation module is configured to calculate the overall alteration degree of the full-section altered rock according to the rock powder plasticity index and the fine particle weight percentage. The specific calculation formula is as follows:

[0120]

[0121] Among them, GAI is the overall alteration degree, α is the clay plasticity index, IP is the rock powder plasticity index, and λ is the percentage of fine particle weight;

[0122] A risk index determination module is configured to respectively determine the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock according to the overall alteration degree, surrounding rock block size and groundwater development characteristics;

[0123] The excavation risk index calculation module is configured to calculate the excavation risk index of the full-section altered rock by combining the overall alteration risk index, the block risk index and the groundwater development risk index.

[0124] Specifically, the index calculation system is composed of an influencing factor acquisition module, an alteration degree calculation module, a risk index determination module, and an excavation risk index calculation module. Among them, the influencing factor acquisition module can obtain the rock powder plasticity index and fine particle weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area. The alteration degree calculation module can calculate the overall alteration degree of the full-section altered rock using the above calculation formula based on the rock powder plasticity index and weight percentage. The risk index determination module can determine the overall alteration risk index, block risk index, and groundwater development risk index of the full-section altered rock based on the overall alteration degree of the full-section altered rock, the surrounding rock block size, and the groundwater development characteristics. The excavation risk index calculation module can calculate the excavation risk index of the full-section altered rock by combining the overall alteration risk index, block risk index, and groundwater development risk index, providing a scientific basis for the identification and prevention of the excavation risk of clay-altered rock tunnels.

[0125] Embodiment 5

[0126] like Figure 3 The system block diagram of the clay-altered rock tunnel excavation risk index calculation system shown in FIG. 1 includes:

[0127] a type analysis module configured to determine the altered rock type to which the clay-altered altered rock in the tunnel excavation area belongs;

[0128] A risk index module, configured to collect corresponding influencing factors according to the altered rock type and calculate the excavation risk index of the clay-altered rock tunnel;

[0129] When the altered rock type is a full-section type, the excavation risk index of the clay-altered rock tunnel is calculated by using the full-section altered rock tunnel excavation risk index calculation method as described in any one of claims 1 to 3.

[0130] Specifically, the calculation system is composed of a type analysis module and a risk index module. Among them, the type analysis module can determine the altered rock type to which the altered rock belongs according to the surrounding rock characteristics during the excavation process. The risk index module can collect corresponding influencing factors based on the altered rock type to which the surrounding rock of the excavation area belongs, and use the corresponding algorithm in Example 2 to calculate the excavation risk index of the excavation area corresponding to various altered rock types, so as to provide a scientific basis for the risk identification and prevention and control of clay-altered rock tunnel excavation.

[0131] Embodiment 6

[0132] like Figure 4 The system block diagram of the clay-altered rock tunnel excavation risk identification system shown in FIG. 1 includes:

[0133] An excavation risk index module is configured to calculate the excavation risk index of the clay-altered rock tunnel using the clay-altered rock tunnel excavation risk index calculation method as described above;

[0134] The excavation risk identification module is configured to determine the risk level and risk type of clay-altered rock tunnel excavation according to the excavation risk index.

[0135] Specifically, the identification system is composed of an excavation risk index module and an excavation risk identification module. Among them, the excavation risk index module can use the clay-altered rock tunnel excavation risk index calculation method recorded in Example 2 to calculate the excavation risk index of altered rock in the excavation area. The excavation risk identification module can match the calculated risk index with the corresponding risk level comparison table to determine the excavation risk level and risk type of the surrounding rock, so as to provide a scientific basis for the prevention and control of clay-altered rock tunnel excavation.

[0136] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention.

Claims

1. A method for calculating the risk index of full-section altered rock tunnel excavation, characterized in that: include: Obtain the rock powder plasticity index and fine-grained weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area; The overall alteration degree of the full-section altered rock is calculated based on the rock powder plasticity index and the percentage of fine particle weight. The specific calculation formula is as follows: Among them, GAI is the overall alteration degree, α is the clay plasticity index, IP is the rock powder plasticity index, and λ is the percentage of fine particle weight; Determine the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock respectively according to the overall alteration degree, surrounding rock block size and groundwater development characteristics; The excavation risk index of the full-section altered rock is calculated by combining the overall alteration risk index, block risk index and groundwater development risk index.

2. The method for calculating the risk index of full-section altered rock tunnel excavation according to claim 1 is characterized in that: Obtain the rock powder plasticity index of the full-section altered rock in the tunnel excavation area after full collapse, including: Testing the liquid limit and plastic limit of rock powder after the full-section altered rock is fully disintegrated; The rock powder plasticity index is calculated based on the liquid limit and plastic limit of the rock powder.

3. The method for calculating the risk index of full-section altered rock tunnel excavation according to claim 1 is characterized in that: The specific calculation formula of the excavation risk index of the full-section altered rock is as follows: R = A1A2η; Among them, A1 is the overall alteration risk index, A2 is the block risk index, and η is the groundwater development risk index.

4. A method for calculating the risk index of tunnel excavation in clay-altered rock, characterized in that: include: Determine the altered rock type to which the clay-altered rock in the tunnel excavation area belongs. According to the characteristics of the tunnel surrounding rock, the altered rock is divided into two types: vein type and full-section type. The full-section type altered rock mass is broken and loose, with severe clay-alteration and no dominant structural surface. The exposed surrounding rock shows sandification and mudification. The vein type is associated with structural surfaces or basic intrusive veins, with a width of 0.1 to 2 meters, and the rock blocks are easy to slide along the structural surface. Collect corresponding influencing factors according to the altered rock type, and calculate the excavation risk index of the clay-altered rock tunnel; When the altered rock type is a full-section type, the excavation risk index of the clay-altered rock tunnel is calculated by using the full-section altered rock tunnel excavation risk index calculation method as described in any one of claims 1 to 3.

5. The method for calculating the risk index of clay-altered rock tunnel excavation according to claim 4 is characterized in that: When the altered rock is a vein-type altered rock, the spatial occurrence, vein width, number of veins, axial angle of the vein relative to the tunnel and groundwater development characteristics of the altered vein are obtained; The risk index of altered dyke type occurrence is determined based on the axial angle and spatial occurrence; the risk index of dyke width density is determined based on the dyke width and number of dykes; and the risk index of groundwater development is determined based on the groundwater development characteristics; Calculate the excavation risk index of the clay-altered rock tunnel according to the vein type occurrence risk index, vein width density risk index and groundwater development risk index; R2=D1D2D3η; Among them, R2 is the excavation risk index of vein-type altered rock, D1 is the vein-type occurrence risk index of vein-type altered rock, D2 is the vein width density risk index of vein-type altered rock, and D3 is the clay alteration index.

6. A method for identifying risks in tunnel excavation in clay-altered rock, characterized in that: include: The excavation risk index of the clay-altered rock tunnel is calculated by using the method for calculating the excavation risk index of the clay-altered rock tunnel as claimed in claim 4; The risk level and risk type of clay-altered rock tunnel excavation are determined based on the excavation risk index.

7. A full-section altered rock tunnel excavation risk index calculation system, characterized in that: include: The influencing factor acquisition module is configured to obtain the rock powder plasticity index and fine particle weight percentage of the full-section altered rock in the tunnel excavation area after full disintegration, as well as the groundwater development characteristics and surrounding rock block size in the tunnel excavation area; The alteration degree calculation module is configured to calculate the overall alteration degree of the full-section altered rock according to the rock powder plasticity index and the fine particle weight percentage. The specific calculation formula is as follows: Among them, GAI is the overall alteration degree, α is the clay plasticity index, IP is the rock powder plasticity index, and λ is the percentage of fine particle weight; A risk index determination module is configured to respectively determine the overall alteration risk index, block risk index and groundwater development risk index of the full-section altered rock according to the overall alteration degree, surrounding rock block size and groundwater development characteristics; The excavation risk index calculation module is configured to calculate the excavation risk index of the full-section altered rock by combining the overall alteration risk index, the block risk index and the groundwater development risk index.

8. A system for calculating the risk index of tunnel excavation in clay-altered rock, characterized in that: include: a type analysis module configured to determine the altered rock type to which the clay-altered altered rock in the tunnel excavation area belongs; A risk index module, configured to collect corresponding influencing factors according to the altered rock type and calculate the excavation risk index of the clay-altered rock tunnel; When the altered rock type is a full-section type, the excavation risk index of the clay-altered rock tunnel is calculated by using the full-section altered rock tunnel excavation risk index calculation method as described in any one of claims 1 to 3.

9. A risk identification system for tunnel excavation in clay-altered rock, characterized in that: include: An excavation risk index module, configured to calculate the excavation risk index of the clay-altered rock tunnel using the clay-altered rock tunnel excavation risk index calculation method as claimed in claim 4; The excavation risk identification module is configured to determine the risk level and risk type of clay-altered rock tunnel excavation according to the excavation risk index.

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