A method and system for underground cavern design based on multiple indicators

Abstract

The present invention provides a method and system for underground cavern design based on multiple indicators, the method comprising the following steps: S1, constructing a comprehensive index H for underground cavern support design; S2, determining the value range and calculation formula of different indicators; S3, generating an engineering case library based on Pairwise technology; S4, calculating the design support pressure based on the H value; S5, proposing general support design principles and requirements for underground caverns; S6, constructing an underground cavern support parameter design table based on rock mass structure and strength characteristics, H value and cavern excavation span; S7, constructing an underground cavern group support design system based on the comprehensive index H and underground cavern span. The present invention can quickly and quantitatively evaluate the rock mass excavation response mode, calculate the design support pressure required for the underground cavern, and determine detailed design support parameters and types, thereby providing a basis for support design and safety and stability evaluation in rock mass underground engineering.

Description

Technical Field

[0001] The invention belongs to the technical field of rock mass underground engineering, and in particular relates to a method and system for underground cavern design based on multiple indicators. Background Art

[0002] In rock mass engineering, the surrounding rock mass, as the self-bearing structure of underground engineering, bears most of the underground engineering load. During the excavation disturbance and stress adjustment of the surrounding rock mass, its stress-strain mechanical response, deformation failure mode and bearing mechanism are crucial to the safety and stability of the underground engineering. In the practice of underground engineering construction, it is necessary to propose design indicators that can fully reflect the mechanical response characteristics, fracture mechanism and bearing capacity evolution law of the surrounding rock mass throughout the whole process, and take this as the core to guide the relevant design of the cavern group.

[0003] Domestic underground cavern support design mainly recommends support parameters based on engineering analogy, qualitative and semi-quantitative analysis according to rock mass type and cavern span. Foreign countries have also summarized the support design parameters of underground caverns based on RMR, Q value, etc., but these support design systems each have certain defects: the Q system does not directly use rock properties as input parameters, but these properties are indirectly reflected in other parameters; the RMR system includes the situation where the initial ground stress level reaches 25MPa, but does not cover the high ground stress problems in the tunnel (such as rock burst, extrusion deformation, etc.); all existing systems do not directly consider rock strength as an important input parameter for support design. Summary of the invention

[0004] The first purpose of the present invention is to provide an underground cavern design method based on multiple indicators to solve the shortcomings of the existing support design system in terms of ground stress, rock burst and excavation response of compression deformation, and the cavern span mainly within the scale range of 30m. At the same time, the empirically designed support system cannot directly consider the important influence of the two parameters of rock mass peak strength and residual strength on the stability of the underground cavern rock mass and support design.

[0005] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0006] A method for designing underground caverns based on multiple indicators, characterized in that the method comprises the following steps:

[0007] S1. Construct the comprehensive index H for underground cavern support design;

[0008] The practice of underground cavern engineering shows that surrounding rock stability and support design are mainly affected by factors such as rock mass quality, ground stress, rock mass peak strength and residual strength, cavern span, cavern excavation section type, excavation construction method, etc. In order to ensure the scientificity and rationality of the evaluation of surrounding rock stability characteristics and support design, a comprehensive index H that can reflect the influence of the above multiple factors is constructed. According to the influence of different factors on cavern surrounding rock stability and support design, the above factors are integrated into 3 basic factors and 3 influencing factors, and these 6 factors are constructed in the following way: basic factors are added, and influencing factors are multiplied as coefficients to construct the comprehensive index H;

[0009] The construction of the comprehensive index H is based on: basic factors × influencing factors, where the basic factors are the sum of the three factors and the influencing factors are the product of the three factors;

[0010] The basic factors are: rock mass quality score, rock mass peak strength, rock mass residual strength;

[0011] The influencing factors are: ground stress, tunnel type, and construction method;

[0012] S2. Determine the value range and calculation formula of different indicators;

[0013] The maximum total score of the three basic factors is 100;

[0014] S3, Generate engineering case library based on Pairwise technology;

[0015] S4, design support pressure calculation formula based on H value;

[0016] The calculation formulas for design support pressure of underground cavern top arch and side wall are different;

[0017] The support pressure calculation formula can consider only the H value, or consider both the H value and the cavern span;

[0018] S5. Propose general support design principles and requirements for underground caverns;

[0019] The general requirements of support design are determined from a macroscopic perspective based on the H value, the stress after cavern excavation and the ratio of the uniaxial compressive strength of rock;

[0020] Determine the macro classification of the surrounding rock stability and support design requirements of the underground cavern top arch and side walls based on the H value and the underground cavern span;

[0021] S6. The design table of underground cavern support parameters was constructed based on the rock mass structure and strength characteristics, H value and cavern excavation span;

[0022] The rock mass is divided into hard and brittle massive rock mass (continuous, with obvious brittle characteristics) and highly jointed or broken rock mass (discontinuous, with obvious ductile characteristics);

[0023] The horizontal axis in the design table is the ratio of the H value to the span of the cavern. Conventional design support parameters such as anchor bolts, shotcrete, arch frame, concrete lining, etc. can be formulated according to different rock mass excavation response modes;

[0024] S7. Construct an underground cavern group support design system based on the comprehensive index H and the span of the underground cavern;

[0025] The design system can quickly determine the design parameters based on the H value and the span of the underground cavern in a graphical manner;

[0026] In the design system, the horizontal coordinate is H value, the secondary horizontal coordinate includes anchor cable spacing, anchor rod spacing, and spray layer thickness parameters, the main vertical coordinate is the cavern span D, and the secondary vertical coordinate includes anchor rod and anchor cable design length parameters;

[0027] The design system includes 9 support (combination) types. The design support type and detailed support parameters can be obtained according to the H value and cavern span.

[0028] While adopting the above technical solutions, the present invention may also adopt or combine the following technical solutions:

[0029] As a preferred technical solution of the present invention:

[0030] Among the basic factors, the rock mass quality score ranges from 10 to 60, the rock mass peak strength score ranges from 0 to 25, and the rock mass residual strength score ranges from 0 to 15;

[0031] Among the influencing factors, the value range of the ground stress correction factor is 0.5-1.0;

[0032] The cave shape correction factor takes into account the cave span, cave shape (circular, horseshoe, city gate), and height-to-span ratio. The cave shape correction factor values ​​for the cave top arch and side wall are different, and the range of the cave shape correction factor for the top arch and side wall is 0.5-1.1.

[0033] The correction factor for the excavation construction method ranges from 0.90 to 1.0.

[0034] As a preferred technical solution of the present invention: step S3 specifically includes:

[0035] The construction of the engineering case includes five main influencing factors of underground cavern excavation response and support design: burial depth, lithology, uniaxial compressive strength of rock block UCS, geological strength index GSI and cavern span. The cavern section type takes the circular section as an example.

[0036] The burial depth range covers the conventional burial depth of underground caverns, 100-400m;

[0037] Lithology includes three major rock types: igneous rock, metamorphic rock and sedimentary rock;

[0038] The uniaxial compressive strength of rock is in the range of 20-150MPa, which is commonly seen in engineering;

[0039] The value range of the geological strength index GSI covers five rock mass quality types of Class IV, which is 20-80;

[0040] The diameter of the circular cavern (cave span) is the common span range of underground caverns, 5-30m;

[0041] Based on the Pairwise method, we achieve complete coverage of the pairwise combinations of the above five factors, making the resulting case set the most cost-effective.

[0042] As a preferred technical solution of the present invention: in the step S4, the support design parameters are obtained by looking up the table according to the Q system, and then the ultimate support pressure is calculated according to different types of support parameters.

[0043] As a preferred technical solution of the present invention: in the step S4, according to the existing support pressure calculation formula based on Q value, cavern span and structural surface roughness coefficient, a calculation formula for support pressure and H value is finally constructed.

[0044] Another object of the present invention is to provide a multi-index based underground cavern design system based on the design method described above.

[0045] To this end, the above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0046] A multi-index-based underground cavern design system, characterized in that: the multi-index-based underground cavern design system is based on the multi-index-based underground cavern design method described above, and includes:

[0047] The design system can quickly determine the design parameters based on the H value and the span of the underground cavern in a graphical manner;

[0048] In the design system, the horizontal coordinate is H value, the secondary horizontal coordinate includes anchor cable spacing, anchor rod spacing, and spray layer thickness parameters, the main vertical coordinate is the cavern span D, and the secondary vertical coordinate includes anchor rod and anchor cable design length parameters;

[0049] The design system includes 9 support (combination) types. The design support type and detailed support parameters can be obtained according to the H value and cavern span.

[0050] The present invention provides an underground cavern design system and system based on a comprehensive index H value under the influence of multiple factors such as rock mass quality, rock mass peak strength, rock mass residual strength, ground stress, cavern geometry, excavation construction methods, etc. The constructed index is a design index, not a geological index, and does not directly use the rock mass quality evaluation index RMR or Q value as an index; the index system includes rock mass quality evaluation and factors that are not considered or not considered sufficiently by the existing experience system; based on engineering cases, the weights of various indicators are adjusted with the design support pressure as the goal, so that it conforms to the existing support experience design system. Compared with the prior art, it has the following beneficial effects:

[0051] The present invention constructs a comprehensive index H based on six indicators of rock mass quality, rock mass peak strength, rock mass residual strength, ground stress, cavern geometry and excavation method and a quantitative scoring basis, thereby realizing rapid determination of underground cavern excavation response, support pressure and support parameters, and can solve the deficiencies of existing design support systems in terms of large span, deep burial, rock mass strength characteristics and the like; in particular, it can rapidly and quantitatively evaluate the rock mass excavation response mode, calculate the design support pressure required for the underground cavern, and determine detailed design support parameters and types, thereby providing a basis for support design and safety and stability evaluation in rock mass underground engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 This is a flow chart of the underground cavern design method based on multiple indicators provided by the present invention.

[0053] Figure 2 This is a schematic diagram of the general support design principles determined based on the comprehensive index H value and stress intensity ratio.

[0054] Figure 3 Schematic diagram for determining the stability and support requirements of the cavern roof based on the comprehensive indicator H value and the span of the underground cavern.

[0055] Figure 4 A schematic diagram of the detailed design support and support type for the cavern is provided based on the comprehensive index H value and the span of the underground cavern.

[0056] Figure 5 It is the general diagram of the cavern support design system based on the comprehensive index H value and the span of the underground cavern. DETAILED DESCRIPTION

[0057] The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0058] The present invention provides a multi-index-based underground cavern design method to achieve full coverage of underground cavern rock excavation response and support design influencing factors, and constructs a quantitative scoring method for comprehensive indicators to address the deficiencies of existing design support systems in terms of large span, deep burial, rock mass strength characteristics, etc. It can quickly and quantitatively evaluate the rock mass excavation response mode, calculate the design support pressure required for the underground cavern, and determine detailed design support parameters and types.

[0059] like Figure 1 As shown, a multi-index-based underground cavern design method includes:

[0060] S1. Construct the comprehensive index H for underground cavern support design;

[0061] In particular, the practice of underground cavern engineering shows that surrounding rock stability and support design are mainly affected by factors such as rock mass quality, ground stress, rock mass peak strength and residual strength, cavern span, cavern excavation section type, excavation construction method, etc. In order to ensure the scientificity and rationality of the evaluation of surrounding rock stability characteristics and support design, a comprehensive index H that can reflect the influence of the above multiple factors is constructed. According to the degree of influence of different factors on cavern surrounding rock stability and support design, the above factors are integrated into 3 basic factors and 3 influencing factors, and these 6 factors are added according to the basic factors and the influencing factors are multiplied as coefficients to construct the comprehensive index H.

[0062] S2. Determine the value range and calculation formula of different indicators;

[0063] The maximum total score of the three basic factors is 100. Among the basic factors, the rock mass quality score ranges from 10 to 60, the rock mass peak strength score ranges from 0 to 25, and the rock mass residual strength score ranges from 0 to 15.

[0064] Among the influencing factors, the value range of the ground stress correction factor is 0.5-1.0;

[0065] The cavern type correction factor considers three main factors: cavern span, cavern type (circular, horseshoe, city gate), and height-to-span ratio;

[0066] The hole shape correction factors of the cavern top arch and side wall have different values, and the value range of the hole shape correction factors of the top arch and side wall is 0.5-1.1;

[0067] The correction factor for the excavation construction method ranges from 0.90 to 1.0;

[0068] Establish a calculation formula between basic factor scores and specific indicators.

[0069] Table 1 shows the calculation formula of the comprehensive index H value and the value range of different indicators determined according to the six factors affecting the excavation response and support design of underground caverns.

[0070] Table 1

[0071]

[0072]

[0073] S3, Generate engineering case library based on Pairwise technology;

[0074] The construction of the engineering case includes five main influencing factors of underground cavern excavation response and support design: burial depth, lithology, uniaxial compressive strength of rock block UCS, geological strength index GSI and cavern span. The cavern section type takes the circular section as an example.

[0075] The burial depth range covers the conventional burial depth of underground caverns, 100-400m;

[0076] Lithology includes three major rock types: igneous rock, metamorphic rock and sedimentary rock;

[0077] The uniaxial compressive strength of rock is in the range of 20-150MPa, which is commonly seen in engineering.

[0078] The value range of the geological strength index GSI covers five rock mass quality types of Class IV, which is 20-80;

[0079] The diameter of the circular cavern (cave span) is the common span range of underground caverns, 5-30m;

[0080] Based on the Pairwise method, we achieve complete coverage of the pairwise combinations of the above five factors, making the resulting case set the most cost-effective.

[0081] S4, based on the Q system, obtain the support pressure calculation formula based on the H value;

[0082] The calculation formula of support pressure based on H value adopts two different methods, which are as follows:

[0083] Method 1: Obtain support design parameters by looking up the Q system table, and then calculate the ultimate support pressure according to different types of support;

[0084] Method 2: Based on the existing support pressure calculation formula based on Q value, cavern span and structural surface roughness coefficient, the calculation formula of support pressure and H value is finally constructed;

[0085] The calculation formulas for design support pressure of underground cavern top arch and side wall are different;

[0086] The support pressure calculation formula can consider only the H value, or it can consider both the H value and the cavern span.

[0087] S5. Propose general support design principles and requirements for underground caverns, such as Figure 2 and Figure 3 As shown,

[0088] The general requirements of support design are determined from a macroscopic perspective based on the H value, the stress after cavern excavation and the ratio of the uniaxial compressive strength of rock;

[0089] The macro-classification of the surrounding rock stability and support design requirements of the underground cavern top arch and side walls is determined based on the H value and the span of the underground cavern.

[0090] S6. According to the rock mass structure and strength characteristics, H value and cavern excavation span, the underground cavern support parameter design table is constructed, such as Figure 4 As shown:

[0091] In the support design table, rock mass is divided into hard brittle blocky rock mass (continuous, obvious brittle characteristics) and highly jointed or broken rock mass (discontinuous, obvious ductile characteristics);

[0092] The horizontal axis in the design table is the ratio of the H value to the cavern span;

[0093] Conventional design support parameters such as anchor bolts, shotcrete, arches, and concrete lining can be formulated according to different rock mass excavation response modes;

[0094] S7. Construct an underground cavern group support design system based on the comprehensive index H and the span of the underground cavern, such as Figure 5 As shown:

[0095] The design system can quickly determine the design parameters based on the H value and the span of the underground cavern in a graphical manner;

[0096] In the design system, the horizontal coordinate is H value, the secondary horizontal coordinate includes the anchor cable spacing, anchor rod spacing, and spray layer thickness parameters, the main vertical coordinate is the cavern span D, and the secondary vertical coordinate includes the anchor rod and anchor cable design length parameters;

[0097] The design system includes 9 support (combination) types. The design support type and detailed support parameters can be obtained according to the H value and cavern span.

[0098] The present invention also provides an underground cavern group support design system based on the comprehensive index H and the span of the underground cavern, such as Figure 5 As shown, the design system can quickly determine the design parameters based on the H value and the span of the underground cavern in a graphical manner;

[0099] In the design system, the horizontal coordinate is H value, the secondary horizontal coordinate includes the anchor cable spacing, anchor rod spacing, and spray layer thickness parameters, the main vertical coordinate is the cavern span D, and the secondary vertical coordinate includes the anchor rod and anchor cable design length parameters;

[0100] The design system includes 9 support (combination) types. The design support type and detailed support parameters can be obtained according to the H value and cavern span.

[0101] The present invention constructs a comprehensive index H value based on six important indicators that affect the excavation response and support design of underground caverns, proposes a quantitative value-taking method for each indicator, and proposes a calculation formula for the design support pressure of the cavern top arch and side wall based on the H value; proposes general support design principles and requirements for underground caverns; constructs the stability characteristics and support pressure requirements of underground caverns based on the H value and the cavern excavation span; in particular, a design chart of underground cavern support parameters is constructed according to the rock structure and strength characteristics, the H value and the cavern excavation span, which expands the applicability of this method in engineering design.

[0102] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for underground cavern design based on multiple indicators. Features: The method comprises the following steps: S1. Construct the comprehensive index H for underground cavern support design; The construction of the comprehensive index H is based on: the sum of basic factors × the product of influencing factors, where the sum of basic factors is the sum of rock mass quality score, rock mass peak strength, and rock mass residual strength, and the product of influencing factors is the product of ground stress, tunnel type, and construction method. S2. Determine the value range and calculation formula of the indicators of different factors; The maximum total score of the three basic factors is 100; S3, Generate engineering case library based on Pairwise technology; S4, obtaining a calculation formula for design support pressure based on the H value; The calculation formulas for design support pressure of underground cavern top arch and side wall are different; The formula for calculating the support pressure only considers the H value, or considers both the H value and the cavern span; S5. Propose general support design principles and requirements for underground caverns; The general requirements of support design are determined from a macroscopic perspective based on the H value, the stress after cavern excavation and the ratio of the uniaxial compressive strength of rock; Determine the macro classification of the surrounding rock stability and support design requirements of the underground cavern top arch and side walls based on the H value and the underground cavern span; S6. Construct the design table of underground cavern support parameters according to rock mass structure and strength characteristics, H value and cavern excavation span; Rock mass is divided into hard and brittle massive rock mass and highly jointed or broken rock mass; The horizontal axis in the design table is the ratio of the H value to the span of the cavern. Conventional design support parameters for anchors, shotcrete, arches, and concrete linings can be formulated based on different rock mass excavation response modes. S7. Construct an underground cavern group support design system based on the comprehensive index H and the span of the underground cavern; The design system can quickly determine the design parameters based on the H value and the span of the underground cavern in a graphical manner; In the design system, the horizontal coordinate is H value, the secondary horizontal coordinate includes anchor cable spacing, anchor rod spacing, and spray layer thickness parameters, the main vertical coordinate is the cavern span D, and the secondary vertical coordinate includes anchor rod and anchor cable design length parameters; The design system includes 9 support types. The design support type and detailed support parameters can be obtained according to the H value and the span of the cavern. The 9 support types include: N / R: no support or random support; (RB) + SC: system spraying + random anchor support; RB+SC: system spraying + system anchor support; RB+SC+(SR)+PAC: system spraying layer+system anchor rod+system anchor cable+random steel arch support; R+SC+SR: system spraying + system anchor + system steel arch support; RB+SC+SR+QL+PAC: system spraying layer+system anchor rod+system steel arch frame+concrete village surface+prestressed anchor cable support: RB+SC+PAC: system spraying + system anchor rod + system anchor cable support; RB+SC+SR+CL: system spraying + system anchor + system steel arch + concrete lining support.

2. The underground cavern design method based on multiple indicators according to claim 1, Features: Among the basic factors, the rock mass quality score ranges from 10 to 60, the rock mass peak strength score ranges from 0 to 25, and the rock mass residual strength score ranges from 0 to 15; Among the influencing factors, the ground stress correction factor ranges from 0.5 to 1.0; the cave type correction factors of the cavern top arch and side walls have different values, and the value range of the cave type correction factors of the top arch and side walls is 0.5-1.1; the correction factor of the excavation construction method ranges from 0.90 to 1.

0.

3. The underground cavern design method based on multiple indicators according to claim 1, Features: Step S3 specifically includes: The construction of the engineering case includes five main influencing factors of underground cavern excavation response and support design: burial depth, lithology, uniaxial compressive strength of rock block UCS, geological strength index GSI and cavern span. The cross-section type of the cavern is a circular cross-section. The burial depth range covers the conventional burial depth of underground caverns, 100-400 m; Lithology includes three major rock types: igneous rock, metamorphic rock and sedimentary rock; The uniaxial compressive strength of rock is 20-150 MPa; The value range of the geological strength index GSI covers five rock mass quality types of Class IV, which is 20-80; The diameter of the circular cavern is the common span range of underground caverns, 5-30 m; Based on the pairwise method, the above five factors are fully covered in combination with each other.

4. The underground cavern design method based on multiple indicators according to claim 1, Features: In step S4, the support design parameters are obtained by looking up the table according to the Q system, and then the ultimate support pressure is calculated according to different types of support parameters.

5. The underground cavern design method based on multiple indicators according to claim 1, Features: In step S4, according to the existing support pressure calculation formula based on Q value, cavern span and structural surface roughness coefficient, a calculation formula for support pressure and H value is finally constructed.

6. A multi-index-based underground cavern design system, Features: The multi-index-based underground cavern design system is based on the multi-index-based underground cavern design method according to any one of claims 1 to 5, and includes: The design system can quickly determine the design parameters based on the H value and the span of the underground cavern in a graphical manner; In the design system, the horizontal coordinate is H value, the secondary horizontal coordinate includes anchor cable spacing, anchor rod spacing, and spray layer thickness parameters, the main vertical coordinate is the cavern span D, and the secondary vertical coordinate includes anchor rod and anchor cable design length parameters; The design system includes 9 support types. The design support type and detailed support parameters can be obtained according to the H value and cavern span.

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