A high-geothermal-zone rock burst grade prediction method

Abstract

The application discloses a high-geothermal-zone rock burst grade prediction method, which comprises the following steps: in-situ testing in a high-geothermal zone to obtain a test result; obtaining a high-geothermal critical buried depth, a high-geothermal rock burst buried depth and a rock mass integrity rock burst correction coefficient according to the test result; obtaining a rock burst buried depth tendency coefficient according to the high-geothermal critical buried depth and the high-geothermal rock burst buried depth; obtaining a rock mass integrity rock burst tendency coefficient according to the rock mass integrity rock burst correction coefficient; and obtaining a prediction result of a high-low-geothermal-zone rock burst grade according to the rock burst buried depth tendency coefficient and the rock mass integrity rock burst tendency coefficient. The application can realize rock burst grade prediction under high-geothermal conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of road construction, and particularly relates to a high-geothermal-zone rock burst grade prediction method. BACKGROUND

[0002] With the gradual development of underground tunnel engineering towards large buried depth, high geothermal has become a major problem faced by underground tunnel engineering, and in addition, the geological conditions in the western region of China are complex, so the difficult high-geothermal rock burst problem often occurs in the construction process of large projects. Although many scholars at home and abroad have carried out a large number of researches on rock burst occurrence conditions, influencing factors, rock burst prediction and criteria, etc., there are few researches on rock burst under high-geothermal conditions, and how to reasonably predict high-geothermal rock burst has become the key to tunnel construction.

[0003] Some existing rock burst intensity classification schemes use the finite element method and Kirsch equation σt=σ1-σ3 to calculate the maximum tangential stress σ θ of the tunnel wall, use σ θ and the rock sample point load strength I s value to draw a rock burst intensity and tunnel wall σ θ and I s relationship diagram, which is used to predict and determine the rock burst grade; some scholars have proposed that the rock burst activity is determined by the ratio of the sum of the tangential stress σ θ and the axial stress σ L of the chamber to the uniaxial compressive strength σ c , that is, Some scholars believe that the accumulated elastic strain energy in the rock is the internal dominant factor of rock burst, and propose that when the rock sample is loaded to (0.7-0.8) R b and then unloaded to 0.05 R b (R b is the uniaxial compressive strength), the ratio of the released elastic strain energy Φ SP to the dissipated elastic strain energy Φ ST is defined as the elastic energy index W ET , which is used to determine and predict rock burst, that is,

[0004] The above rock burst discrimination criteria are suitable for rock burst grade prediction under general conditions, and do not consider rock burst under high-geothermal conditions. Obviously, the traditional discrimination method is difficult to make targeted criteria for rock burst under high-geothermal conditions. Rock burst in tunnel construction under high-geothermal conditions has a greater impact on engineering safety, progress and investment, and rock burst under this condition is often more frequent and severe than rock burst under general conditions. Therefore, rock burst grade prediction under high-geothermal conditions has become a very important problem in tunnel construction. SUMMARY

[0005] The present application aims to provide a high-geothermal-zone rock burst grade prediction method, so as to realize rock burst grade under high-geothermal conditions and thus to predict rock burst.

[0006] The technical solution of the present application to solve the above technical problems is as follows:

[0007] In fact, the influence of temperature on rock mass integrity is very small, but the more intense the activity of the fracture zone is, the higher the temperature of the surrounding rock will be, so the higher the temperature of the surrounding rock in the high-geothermal zone is, the more broken the structure of the rock mass will be, and the lower the rock burst grade of the surrounding rock will be. Therefore, the higher the temperature of the surrounding rock in the high-geothermal zone is, the worse the rock mass integrity of the surrounding rock will be, and the lower the rock burst grade will be. In combination with this idea, the present application provides a high-geothermal-zone rock burst grade prediction method, which comprises:

[0008] In-situ testing is performed in the high-geothermal zone to obtain a test result;

[0009] According to the test result, a high-geothermal-zone critical buried depth, a high-geothermal-zone rock burst buried depth, and a rock mass integrity rock burst correction coefficient are obtained;

[0010] According to the high-geothermal-zone critical buried depth and the high-geothermal-zone rock burst buried depth, a rock burst buried depth tendency coefficient is obtained;

[0011] According to the rock mass integrity rock burst correction coefficient, a rock mass integrity rock burst tendency coefficient is obtained;

[0012] According to the rock burst buried depth tendency coefficient and the rock mass integrity rock burst tendency coefficient, a prediction result of high-low-geothermal-zone rock burst grade is obtained.

[0013] Optionally, the test result comprises a temperature T, a deformation modulus E, a Poisson's ratio μ, a rock bulk density r, a horizontal ground stress σ x , a vertical ground stress σ y , a rock mass integrity coefficient Kv, a rock quality designation RQD, a number of joint strips per unit volume of rock mass Jv, a maximum tangential stress σ θ of the surrounding rock, and a rock uniaxial compressive strength R c .

[0014] Optionally, obtaining the high-geothermal-zone critical buried depth, the high-geothermal-zone rock burst buried depth, and the rock mass integrity rock burst correction coefficient according to the test result comprises:

[0015] According to the temperature T, the Poisson's ratio μ, the rock bulk density r, and the rock uniaxial compressive strength R c in the test result, a high-geothermal-zone critical buried depth H cr is obtained;

[0016] Based on the horizontal ground stress σ in the test results x and vertical ground stress σ y The ratio K of horizontal stress to vertical stress is obtained. σ ;

[0017] According to the ratio K of horizontal stress to vertical stress σ The high-temperature rockburst burial depth Z is obtained from the deformation modulus E in the test results.

[0018] Based on the table of average joint spacing and joint development degree coefficient, the joint development degree coefficient F of the high temperate zone is determined. s ;

[0019] Based on the rock mass integrity coefficient Kv, rock quality index RQD, number of joints per unit volume of rock mass Jv, and the joint development degree coefficient F... s The rock burst correction coefficient for rock mass integrity was obtained.

[0020] Alternatively, the critical burial depth for high geothermal temperatures is:

[0021]

[0022] Among them, H cr The critical burial depth for high geothermal zones is given by T, where T is the temperature of the high geothermal zone, μ is Poisson's ratio, r is the rock density, and R is the density of the rock. c It represents the uniaxial compressive strength of the rock.

[0023] Alternatively, the burial depth of the high-temperature rockburst is:

[0024]

[0025] Where Z is the burial depth of high-temperature rockburst, E is the deformation modulus, and K is the burial depth of high-temperature rockburst. σ For horizontal ground stress σ x and vertical ground stress σ y The ratio.

[0026] Alternatively, the rock burst correction factor for rock mass integrity is:

[0027]

[0028] Where K is the rock burst correction factor for rock mass integrity, Kv is the rock mass integrity factor, RQD is the rock quality index, Jv is the number of joints per unit volume of rock mass, and F s This represents the coefficient of joint development degree.

[0029] Alternatively, the rockburst burial depth tendency coefficient is:

[0030]

[0031] Where F is the rockburial depth tendency coefficient, Z is the high-temperature rockburial depth, and H cr This is the critical burial depth for high geothermal conditions.

[0032] Alternatively, the rock burst tendency coefficient for rock mass integrity is:

[0033]

[0034] Where S is the rock burst tendency coefficient for rock mass integrity, K is the rock burst correction coefficient for rock mass integrity, and R... c σ is the uniaxial compressive strength of rock. θ denoted as the maximum tangential stress of the surrounding rock, and T as the temperature of the high-temperature zone.

[0035] The present invention has the following beneficial effects:

[0036] 1. This invention provides a method for predicting the severity of rockbursts in high-temperature zones. Starting with the causes of high temperatures, considering that high-temperature zones are generally active fault zones with relatively fragmented rock masses, this invention fully considers the influence of joint development on rockbursts. Based on measuring the number of joints per unit volume of rock mass, the joint development degree coefficient F is obtained by referring to the standard table established in this patent. s The rock burst parameter correction coefficient K for rock mass integrity is obtained, and the high-temperature rock burst tendency coefficient is finally obtained through the value of correction coefficient K. This method is based on the influence of rock mass integrity on rock bursts and is applicable to the classification of rock burst levels in all high-temperature zones.

[0037] 2. The rockburst intensity prediction method for high-temperature geothermal zones provided by this invention is used to calculate the rockburst intensity in high-temperature geothermal zones. It considers multiple factors affecting the intensity of rockbursts and finally predicts the rockburst intensity using both the rockburst depth tendency coefficient F and the rock mass integrity rockburst tendency coefficient S. This method fully considers the surrounding rock conditions in high-temperature geothermal zones, making the results more accurate. The discrimination method provided by this invention can provide technical support for rockbursts under high-temperature conditions, allowing for appropriate support based on the rockburst intensity to improve construction safety and efficiency. Attached Figure Description

[0038] Figure 1 The flowchart illustrates the method for predicting rockburst severity in high-temperature zones provided by this invention. Detailed Implementation

[0039] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0040] Example 1

[0041] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0042] This invention provides a method for predicting the intensity of rockbursts in high temperate zones, with reference to... Figure 1 As shown, the method for predicting the intensity of rockbursts in high-temperature zones includes:

[0043] In-situ tests were conducted in the high temperate zone to obtain the test results;

[0044] Optionally, the test results include: temperature T in the high temperate zone, deformation modulus E, Poisson's ratio μ, rock unit weight r, and horizontal in-situ stress σ. x Vertical ground stress σ y Rock mass integrity coefficient Kv, rock quality index RQD, number of joints per unit volume of rock mass Jv, and maximum tangential stress of surrounding rock σ θ and the uniaxial compressive strength R of rock c .

[0045] Based on the test results, the critical burial depth for high geothermal temperatures, the burial depth for high geothermal rockburials, and the rockburial correction coefficient for rock mass integrity were obtained.

[0046] Optionally, the process of obtaining the high-temperature critical burial depth, high-temperature rockburial depth, and rock mass integrity rockburial correction coefficient based on the test results includes:

[0047] Based on the test results, the high-temperature zone temperature T, Poisson's ratio μ, rock bulk density r, and rock uniaxial compressive strength R... c The critical burial depth H of high geothermal temperature was obtained. cr ;

[0048] Alternatively, the critical burial depth for high geothermal temperatures is:

[0049]

[0050] Among them, H cr The critical burial depth for high geothermal zones is given by T, where T is the temperature of the high geothermal zone, μ is Poisson's ratio, r is the rock density, and R is the density of the rock. c It represents the uniaxial compressive strength of the rock.

[0051] Based on the horizontal ground stress σ in the test results x and vertical ground stress σ y The ratio K of horizontal stress to vertical stress is obtained. σ ;

[0052] According to the ratio K of horizontal stress to vertical stress σ The high-temperature rockburst burial depth Z is obtained from the deformation modulus E in the test results.

[0053] Alternatively, the burial depth of the high-temperature rockburst is:

[0054]

[0055] Where Z is the burial depth of high-temperature rockburst, E is the deformation modulus, and K is the burial depth of high-temperature rockburst. σ For horizontal ground stress σ x and vertical ground stress σ y The ratio.

[0056] Based on the table of average joint spacing and joint development degree coefficient, the joint development degree coefficient F of the high temperate zone is determined. s ;

[0057] Here, the joint development degree coefficient table is referenced in Table 1:

[0058] Table 1. Joint Development Degree Coefficient

[0059]

[0060] Based on the rock mass integrity coefficient Kv, rock quality index RQD, number of joints per unit volume of rock mass Jv, and the joint development degree coefficient F... s The rock burst correction coefficient for rock mass integrity was obtained.

[0061] Alternatively, the rock burst correction factor for rock mass integrity is:

[0062]

[0063] Where K is the rock burst correction factor for rock mass integrity, Kv is the rock mass integrity factor, RQD is the rock quality index, Jv is the number of joints per unit volume of rock mass, and F s This represents the coefficient of joint development degree.

[0064] Based on the high-temperature critical burial depth coefficient and the high-temperature rockburial depth coefficient, the rockburial depth tendency coefficient is obtained.

[0065] Alternatively, the rockburst burial depth tendency coefficient is:

[0066]

[0067] Where F is the rockburial depth tendency coefficient, Z is the high-temperature rockburial depth, and H cr This is the critical burial depth for high geothermal conditions.

[0068] Based on the rock burst correction coefficient for rock mass integrity, the rock burst tendency coefficient for rock mass integrity is obtained;

[0069] Alternatively, the rock burst tendency coefficient for rock mass integrity is:

[0070]

[0071] Where S is the rock burst tendency coefficient for rock mass integrity, K is the rock burst correction coefficient for rock mass integrity, and R... c σ is the uniaxial compressive strength of rock. θ denoted as the maximum tangential stress of the surrounding rock, and T as the temperature of the high-temperature zone.

[0072] Based on the rockburial depth tendency coefficient and the rock mass integrity rockburial tendency coefficient, the prediction results of the rockburial level in the high and low temperature zone are obtained.

[0073] The criteria for predicting rockburst severity using the high-temperature rockburst tendency coefficient S and the rockburst burial depth tendency coefficient F are shown in Table 2.

[0074] Table 2 Classification of Rockburst in High Temperate Zones

[0075]

[0076] Example 2

[0077] Compared with existing technologies, this invention starts from the causes of high geothermal temperatures. High-temperature zones are often located in active fault zones with relatively fragmented rock structures. Therefore, based on existing research, this invention focuses on introducing the influence coefficient F of joint development degree. s This invention provides a method for predicting the severity of rockbursts in high-temperate zones. The method first determines the severity based on the number of joints (J) per unit volume of rock mass. v The joint development degree coefficient F is obtained by referring to Table 1 of the standard established in this invention. s Then, by obtaining the temperature T, Poisson's ratio μ, rock density r, and time-delayed uniaxial compressive strength R of the high temperate zone... c The critical burial depth H for high geothermal conditions is determined according to the formula. cr Then through the horizontal ground stress σ x and vertical ground stress σ y The ratio of K to K σ Based on this, and combined with the deformation modulus E, the burial depth Z of high-temperature rockburst is calculated using the formula; and the critical burial depth H of high-temperature rockburst is calculated based on the above. cr The rockburial depth dip coefficient F is calculated using a formula based on the high-temperature rockburial depth Z; the next step is to combine this with the rock mass integrity coefficient K. v The rock quality index RQD and the joint development degree influence coefficient Fs are used to calculate the rock burst correction coefficient K for rock mass integrity according to the formula; thus, the rock burst tendency coefficient S for rock mass integrity is determined according to the formula. Finally, rock bursts are classified according to the rock burst burial depth tendency coefficient F and the rock burst tendency coefficient S for rock mass integrity.

[0078] The following examples will further illustrate this solution.

[0079] In a geologically complex, high-temperature zone severely affected by heat damage, a preliminary assessment of the surrounding rock at a predicted location of potential large deformation was conducted. The measured ground temperature was 39.2℃, placing it in a high-temperature zone. The working face and surrounding rock were composed of grayish-white granite, in a monolithic state. The working face was uneven and exhibited two sets of distinct joints. One set of joints had a spacing of approximately 0.3m, was slightly open, filled, and unweathered. The other set of joints had a spacing of approximately 0.5m, was open, filled with white material, and was unweathered. This condition is applicable to the present invention.

[0080] Step 1: In-situ testing was conducted at the construction site, and the deformation modulus E = 30.5 GPa, Poisson's ratio μ = 0.22, and rock unit weight r = 27 KN / m³ were measured. 3 Horizontal ground stress σ x =42.9MPa, vertical ground stress σ y =37MPa; Rock mass integrity coefficient K v =0.482, rock quality index RQD=95, number of joints per unit volume of rock mass J v =2, maximum tangential stress of surrounding rock σ θ =63.8MPa, uniaxial compressive strength R of rock c =211.896MPa;

[0081] Step 2: Based on the surrounding rock stress measured in Step 1, the ratio K of horizontal stress to vertical stress can be obtained. σ =1.159. Based on the condition that the joint spacing is greater than 0.3m and the joint surface is not weathered, the joint development degree coefficient F is determined from Table 1. s =0.85;

[0082] Step 3: Considering the influence of high geothermal conditions, based on the measured geothermal temperature T = 39.2℃, Poisson's ratio μ = 0.22, and rock bulk density r = 27KN / m³,... 3 Substitute the above data into the formula Calculations were performed to obtain the critical burial depth H for high geothermal conditions. cr =844.86m;

[0083] Step 4: Based on the deformation modulus E = 30.5 GPa obtained in Step 1, and combined with the ratio of horizontal to vertical stress Kσ = ​​1.159 determined in Step 2, substitute it into the formula. Calculations show that the burial depth of the high-temperature rockburst is Z = 1314.98m.

[0084] Step 5: Then, determine the critical burial depth H for high geothermal temperature as shown in Step 3. cr Substituting the values ​​of 844.86m and the high-temperature rockburst burial depth Z = 1314.98m determined in step 4 into the formula... The calculation yielded a rockburst burial depth dip coefficient F = 0.358.

[0085] Step 6: The next step is to use the measured rock mass integrity coefficient K... v =0.482, rock quality index RQD=95, number of joints per unit volume of rock mass J v =2, and step 2 determines the joint development degree coefficient F by looking up the table. s =0.85, substitute into the formula The calculation yielded a rockburst correction factor of K = 1.27 for rock mass integrity.

[0086] Step 7: Substitute the rock burst correction factor K = 1.27 for rock mass integrity determined in Step 6 and the measured high-temperature zone temperature T = 39.2℃ into the formula. The rock burst tendency coefficient for rock mass integrity, calculated in this study, is S = 0.723.

[0087] Step 8: Based on the rockburst burial depth tendency coefficient F = 0.358 and the rock mass integrity rockburst tendency coefficient S = 0.723, the rockburst under high geothermal conditions is classified by referring to Table 2, and it is concluded that the rockburst in this area is a strong rockburst.

[0088] In summary, this invention provides a method for predicting rockburst levels in high-temperate zones. Starting with the causes of high temperatures, and considering that high-temperate zones are generally active fault zones with relatively fragmented rock masses, this invention fully considers the influence of joint development on rockbursts. This method is based on the impact of rock mass integrity on rockbursts, has a clear applicability, and is fully applicable to the classification of rockburst levels in all high-temperate zones.

[0089] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the intensity of rockbursts in high temperate zones, characterized in that, The method for predicting the intensity of rockbursts in high-latitude temperate zones includes: In-situ tests were conducted in the high temperate zone to obtain the test results; Based on the test results, the critical burial depth for high geothermal temperatures, the burial depth for high geothermal rockburials, and the rockburial correction coefficient for rock mass integrity were obtained. Based on the critical burial depth of high geothermal temperature and the burial depth of high geothermal rockburial, the rockburial depth tendency coefficient is obtained; Based on the rock burst correction coefficient for rock mass integrity, the rock burst tendency coefficient for rock mass integrity is obtained; Based on the rockburial depth tendency coefficient and the rock mass integrity rockburial tendency coefficient, the prediction result of the rockburial level in the high-temperature zone is obtained; The test results include: temperatures in the high-latitude temperate zone. T Deformation modulus E Poisson's ratio μ Rock density r Horizontal ground stress σ x Vertical stress σ y Rock mass integrity coefficient Kv Rock quality indicators RQD Number of joints per unit volume of rock mass Jv、 Maximum tangential stress of surrounding rock σ θ and the uniaxial compressive strength of rock R c ; The rockburial depth tendency coefficient is: in, F The rockburial depth dip coefficient is given by the rockburial depth. Z Due to the high temperature of the rock burst, the burial depth is... This is the critical burial depth for high geothermal conditions. The rock burst tendency coefficient for rock mass integrity is: in, S The rock burst tendency coefficient represents the rock mass integrity. K This is the rockburst correction factor for rock mass integrity. R c For the uniaxial compressive strength of rock, σ θ The maximum tangential stress of the surrounding rock. T This refers to the temperature of the high temperate zone.

2. The method for predicting the intensity of rockbursts in high temperate zones according to claim 1, characterized in that, The high-temperature critical burial depth, high-temperature rockburial depth, and rock mass integrity rockburial correction coefficient obtained based on the test results include: Based on the temperature of the high-latitude zone in the test results T Poisson's ratio μ Rock density r and uniaxial compressive strength of rock R c The critical burial depth for high geothermal conditions was obtained. ; Based on the horizontal ground stress in the test results σ x and vertical stress σ y The ratio of horizontal stress to vertical stress was obtained. K σ ; Based on the ratio of horizontal stress to vertical stress K σ and the deformation modulus in the test results E The burial depth of high-temperature rockbursts was obtained. Z ; Based on the table of average joint spacing and joint development degree coefficient, the joint development degree coefficient of the high temperate zone is determined. F s ; Based on rock mass integrity coefficient Kv、 Rock quality indicators RQD, Number of joints per unit volume of rock mass Jv and the joint development degree coefficient F s The rock burst correction coefficient for rock mass integrity was obtained.

3. The method for predicting the intensity of rockbursts in high temperate zones according to claim 2, characterized in that, The critical burial depth for high geothermal temperatures is: in, This is the critical burial depth for high geothermal conditions. T The temperature of the high temperate zone, μ Poisson's ratio, r For the density of the rock, R c It represents the uniaxial compressive strength of the rock.

4. The method for predicting the intensity of rockbursts in high temperate zones according to claim 2, characterized in that, The burial depth of the high-temperature rockburst is: in, Z Due to the high temperature of the rock burst, the burial depth is... E For deformation modulus, K σ Horizontal ground stress σ x and vertical stress σ y The ratio.

5. The method for predicting the intensity of rockbursts in high-temperature temperate zones according to any one of claims 2-4, characterized in that, The rock burst correction factor for rock mass integrity is: in, K This is the rockburst correction factor for rock mass integrity. Kv The rock mass integrity coefficient. RQD As a rock quality indicator, Jv This refers to the number of joints per unit volume of rock mass. F s This represents the coefficient of joint development degree.

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