A method and device for evaluating and supporting the stability of deep surrounding rock

Abstract

The present invention discloses a support method and device for evaluating the stability of deep surrounding rocks, which relates to the technical field of deep surrounding rock support, and includes Step 1: opening holes at the measured parts of the roadway corresponding to deep soft rocks, arranging multi-point displacement gauges in the holes, recording the distances of each measuring point of the multi-point displacement gauge from the roadway surface, and simultaneously measuring and recording the surface displacements of each measuring point through the multi-point displacement gauge at regular intervals; in the present invention, multi-point displacement gauges are arranged at typical parts of the roadway surrounding rocks. According to the displacements of different measuring points of the roadway surrounding rocks measured by the multi-point displacement gauges, the measured data are subjected to regression analysis according to the formula, and then the regression equation coefficients are substituted into the formula to obtain the surface displacement gradient values of each measuring point. Using the surface displacement gradient values as the evaluation index can better reflect the stability differences between the roadway floor and the rib; the stability of the deep soft rock roadway surrounding rocks is judged based on the secondary creep coefficient of the deep soft rock roadway surrounding rocks, so as to facilitate the selection of reasonable support forms and parameters for the deep soft rock roadway.

Description

Technical Field

[0001] The present invention relates to the technical field of deep surrounding rock support, and specifically provides a method and device for evaluating the stability of deep surrounding rock and support thereof. Background Art

[0002] China is rich in mineral resources. With the increase in the scale of coal mine resource exploitation, it has become increasingly difficult to stabilize the surrounding rock of roadways. Selecting reasonable criteria to judge the stability of the surrounding rock and accordingly choosing reasonable support parameters have a wide range of application backgrounds in engineering. The distribution of deep rocks is intricate. During the process of the surrounding rock releasing energy during excavation, a certain range of loosening zones will be generated around it. The worse the lithology and the more elastic energy stored in the rock, the larger the range of the loosening zone. The range of the loosening zone will not increase infinitely. When the surrounding rock is excavated, it changes from the original stable triaxial compression equilibrium state to a biaxial compression state. As energy is released, a new equilibrium state will be reached during the extension of the loosening zone towards the deep part. This state is sometimes stable, and the roadway will not collapse quickly under the self-bearing capacity of the surrounding rock. If encountering rocks with poor lithology, the roadway may be damaged immediately. Analyzing the influencing factors of the thickness of the loosening zone, selecting a reasonable evaluation method, judging the stability of the surrounding rock, and accordingly choosing reasonable support parameters and taking active and effective support measures are very necessary.

[0003] However, the existing methods for judging the stability of the surrounding rock and roadway support do not give applicable conditions under a unified surrounding rock classification, which causes many troubles in selecting roadway support during actual engineering construction. At the same time, the current methods for measuring the thickness of the loosening zone usually include ultrasonic method, seepage method, ground penetrating radar method, borehole camera method, etc. Some of these methods are operationally complex and some are expensive. Therefore, based on the applicability of evaluating the stability of deep soft surrounding rock according to the thickness of the loosening zone, a classification method for the stability of deep soft surrounding rock is proposed to determine the classification of the stability of the surrounding rock of the roadway, and reasonable support forms and parameters are proposed, which can effectively ensure the safe and efficient exploitation of deep coal. Summary of the Invention

[0004] The purpose of the present invention is to propose a method and device for evaluating the stability of deep surrounding rock and support thereof in order to solve the problems that applicable conditions are not given under a unified surrounding rock classification and the existing methods for measuring the thickness of the loosening zone are operationally complex.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] In a first aspect, the present invention provides a method for evaluating the stability of deep surrounding rock and support thereof, the method comprising:

[0007] Step 1: Drill holes at the parts to be measured in the roadway corresponding to deep soft rock, and arrange multi-point displacement gauges in the holes. Record the distance r of each measuring point of the multi-point displacement gauge from the roadway surface. At the same time, measure and record the surface displacement u of each measuring point through the multi-point displacement gauge at regular intervals.

[0008] Step 2: Substitute the distance r of each measuring point from the roadway surface and the surface displacement u into the regression formula , and obtain the values of the regression equation coefficients k0, k1, and k2; then substitute the values of the regression equation coefficients k1 and k2 into the formula to obtain the surface displacement gradient value λ of each measuring point; determine the critical allowable value of the displacement gradient λmin = 10.0 mm / m when the coal and rock of the roadway are in the critical state of loosening and fragmentation; use the formula to obtain the thickness L of the loose circle.

[0009] Step 3: Analyze the characteristics of the surrounding rock deformation of the deep soft rock roadway over time, including the analysis of the primary creep characteristics of the surrounding rock and the analysis of the secondary creep characteristics of the surrounding rock, and then obtain the primary creep speed attenuation coefficient B1 of the surrounding rock and the secondary creep speed attenuation coefficient B2 of the surrounding rock.

[0010] Step 4: Evaluate the stability of the surrounding rock of the deep soft rock roadway with the secondary creep speed attenuation coefficient of the surrounding rock. Among them, the classification of the stability of the surrounding rock of the deep soft rock roadway includes extremely stable state, stable state, basically stable state, unstable state, and extremely unstable state.

[0011] Step 5: Select the support according to the stability of the surrounding rock of the deep soft rock roadway. If it is in an extremely stable state or a stable state, no operation is performed; if it is in an unstable state, timely secondary support is carried out on the surrounding rock of the deep soft rock roadway, and the support strength is enhanced; if it is in an extremely unstable state, a new support design is carried out on the surrounding rock of the deep soft rock roadway; the secondary support is to arrange prestressed anchor cables at the corresponding positions, the length of the anchor cable is CM = L + (0.5 m - 1.0 m), and in the part where the thickness of the loose circle L < 2.5 m, prestressed anchor bolts are arranged, and the length CG of the anchor bolt is determined according to the thickness of the loose circle L, specifically CG = L + (0.3 m - 0.5 m), and finally adjust the row spacing of the anchor cables and the row spacing of the anchor bolts.

[0012] As a preferred embodiment of the present invention, the specific process of the analysis of the primary creep characteristics of the surrounding rock is as follows:

[0013] Obtain the typical curve of the stress and strain of the surrounding rock under the action of triaxial confining pressure of the rock, and divide it into four stages, namely the compaction stage OA of the rock fissures under pressure, the elastic deformation stage AB of the rock, the plastic stage BC of the rock, and the dilatancy failure stage CD.

[0014] When in the plastic stage, it is assumed that the surrounding rock deformation in the plastic deformation zone is volume-incompressible, the roadway shape is circular, the initial in-situ stress field is isotropic, the surrounding rock is a homogeneous isotropic viscoelastic medium, which conforms to the assumptions of continuum mechanics. Since the medium in the plastic zone has incompressibility, the strain state in the plastic zone is expressed in polar coordinates as follows: ; Substitute and into the strain state in the plastic zone expressed in polar coordinates and integrate; where is the tangential strain, is the radial strain, u1 is the radial deformation of the measuring point, and r1 is the distance from the measuring point to the roadway center; the stress in the viscoelastic zone is expressed as: , ; where is the radial stress of the measuring point, is the tangential stress of the measuring point, is the viscosity coefficient, and G is the shear modulus;

[0015] The shear strength of rock [τ] that the rock can bear is determined by the rock cohesion c, the internal friction angle and the normal stress σ on the failure surface, that is, the shear strength of rock ;

[0016] The maximum shear stress on the failure surface is , τ1 is the maximum shear stress on the failure surface, is the maximum principal stress, is the minimum principal stress; , kx is a constant, and its value is custom-defined according to the actual on-site conditions;

[0017] The boundary between the viscoelastic zone and the viscoplastic zone also satisfies , R is the radius of the plastic zone, , both a and b are coefficients, , from t = 0, , it is obtained that a + b = 0, that is , then , let the roadway radius be R0, then r = R0, and the change of the surrounding rock surface deformation with time is ;

[0018] Let , A is the maximum deformation of the surrounding rock surface, , B is the attenuation coefficient of the surrounding rock surface deformation velocity; , when , the stable value of the surrounding rock surface deformation is , taking 0.95 times of the stable value of the surrounding rock surface deformation as the primary creep action time of the surrounding rock, that is , at this time the primary creep action time of the surrounding rock t = 3.0 / B, and the attenuation coefficient B of the surrounding rock surface deformation velocity is determined by the shear modulus G and the viscosity coefficient It is determined that its value B = 0.1 - 0.2, and thus the primary creep action time t = 15 - 30 days.

[0019] As a preferred embodiment of the present invention, the analysis process of the secondary creep characteristics of the surrounding rock is as follows:

[0020] After the surrounding rock deformation undergoes primary creep, if the crushing condition is met, the surrounding rock will be crushed and produce volumetric dilatation, forming secondary creep. The time point when the surrounding rock is in the secondary creep stage days, and the secondary creep stage of the surrounding rock is: , where A1 is the primary creep amount of the surrounding rock; A2 is the secondary creep amount of the surrounding rock, t0 is the primary creep action time of the surrounding rock, B1 is the primary creep speed attenuation coefficient of the surrounding rock, and B2 is the secondary creep speed attenuation coefficient of the surrounding rock.

[0021] As a preferred embodiment of the present invention, the specific evaluation process for evaluating the stability of the surrounding rock of deep soft rock roadways using the secondary creep speed attenuation coefficient of the surrounding rock is as follows: If only primary creep occurs and no secondary creep occurs, it is determined to be in an extremely stable state; if secondary creep occurs and the secondary creep attenuation coefficient B2 ≥ 0.05, it is determined to be in a stable state; if the secondary creep attenuation coefficient B2 ∈ [0.04, 0.05], it is determined to be in a basically stable state; if the secondary creep attenuation coefficient B2 < 0.04, it is determined to be in an unstable state; if the surrounding rock of the deep soft rock roadway only deforms within 5 to 10 days after excavation and enters the accelerated deformation stage, it is determined to be in an extremely unstable state.

[0022] In a second aspect, the present invention provides a support device for evaluating the stability of deep surrounding rock, which is applied to implement a method for evaluating the stability of deep surrounding rock support as described above, and includes:

[0023] A data acquisition unit that records the distances of each measuring point of the multi-point displacement meter from the roadway surface, and at the same time measures and records the surface displacements of each measuring point through the multi-point displacement meter at regular intervals;

[0024] A data analysis unit that analyzes the distances of each measuring point from the roadway surface and the surface displacements, and outputs the surface displacement gradient values and the thickness of the loosening circle of each measuring point;

[0025] A surrounding rock analysis unit that analyzes the characteristics of the deformation of the surrounding rock of the deep soft rock roadway over time, and outputs the primary creep speed attenuation coefficient and the secondary creep speed attenuation coefficient of the surrounding rock;

[0026] A stability evaluation unit that evaluates the stability of the surrounding rock of the deep soft rock roadway using the secondary creep speed attenuation coefficient of the surrounding rock;

[0027] A support selection unit that selects support according to the stability of the surrounding rock of the deep soft rock roadway.

[0028] As a preferred embodiment of the present invention, it further includes a data calibration unit. The data calibration unit collects the displacement meter information of the borehole displacement meter corresponding to the deep soft rock roadway and analyzes and calibrates it. Among them, the displacement meter information includes the number, position, compaction data, and measurement environmental conditions; the compaction data consists of the propagation speed and attenuation degree measured by ultrasonic waves in the grouting hole where the displacement meter is located by an ultrasonic device; the measurement environmental conditions include the environmental temperature and humidity where the displacement meter is located; the specific analysis process is as follows:

[0029] Analyze the compaction data, perform normalization processing on the propagation speed and attenuation degree, and take the values of both, which are marked as Vs1 and Vs2 in sequence; set the weight factors of the propagation speed and attenuation degree as Vk1 and Vk2; substitute the values of the propagation speed and attenuation degree into the preset compaction calculation model MSz = Vs1×Vk1 + 2 / (Vs2×Vk2 + 1) to obtain the compaction value MSz; compare the compaction value with the set compaction threshold. If the compaction value is less than the compaction threshold, mark the displacement data measured corresponding to this displacement meter as the distance from the measuring point to the roadway surface and the surface displacement as invalid data. At the same time, generate a re-grouting instruction for this displacement meter, and send the number, position, and re-grouting instruction of this displacement meter to the intelligent terminal of the corresponding preset processing personnel. After receiving the number, position, and re-grouting instruction of the displacement meter through the intelligent terminal, the preset processing personnel perform re-grouting processing on this displacement meter; if the compaction value is greater than or equal to the compaction threshold, analyze the environmental conditions during measurement, specifically as follows:

[0030] Sort all the environmental temperatures in the order of collection time, set three temperature intervals, namely the high-temperature interval, the normal interval, and the low-temperature interval; match all the environmental temperatures with the three temperature intervals, mark the environmental temperatures in the high-temperature interval as ultra-high temperatures, count the number of ultra-high temperatures to obtain the ultra-high number, calculate the average value and the maximum value of all ultra-high temperatures and mark them as the high average value and the high maximum value; extract the values of the ultra-high number, the high average value, and the high maximum value and input them into the computer. Construct a rhombus with the length line segments corresponding to the ultra-high number and the high average value. Select the center point of the rhombus. Starting from this center point of the rhombus, use the length line segment corresponding to the high maximum value as the height of the rhombus. Construct a quadrangular pyramid with the rhombus and the height, extract the volume of the quadrangular pyramid and mark the value of the volume as the ultra-temperature shadow value; mark the environmental temperatures in the low-temperature interval as low-zone temperatures; sort the low-zone temperatures in the order of time, calculate the time duration between two adjacent low-zone temperatures to obtain the low-interval duration, calculate the average value of all the low-interval duration values to obtain the low-time average value; count the number of low-zone temperatures to obtain the low-zone number; sum up all the low-zone temperatures and take the average value to obtain the low-zone average value; perform normalization processing on the low-time average value, the low-zone number, and the low-zone average value and take the normalized values of the three, which are marked as DS1, DS2, and DS3 in sequence; substitute them into the preset low-temperature model Obtain the low-temperature shadow value DW, where are all preset weight factors. Customize the weight ratios of the low-temperature shadow value and the over-temperature shadow value, multiply the low-temperature shadow value and the over-temperature shadow value by their corresponding weight ratios respectively to achieve weighted calculation, and then sum to output the ambient temperature value. If the ambient temperature value is greater than the set ambient temperature threshold one and less than or equal to the ambient temperature threshold two, then convert the ambient temperature value into a calibration deviation value according to a certain ratio, where the ambient temperature value is proportional to the calibration deviation value, and the larger the ambient temperature value, the larger the calibration deviation value. Then match the calibration deviation value with several preset deviation ranges, and each deviation range corresponds to a distance of a measuring point from the roadway surface and a compensation number for surface displacement. If the calibration deviation value is within the deviation range, add the distance of each measuring point from the roadway surface and the compensation number for surface displacement corresponding to this deviation range to the distance r of each measuring point from the roadway surface and the surface displacement u respectively, and then substitute them into the regression formula. If the ambient temperature value is greater than the ambient temperature threshold two, generate a calibration instruction for this displacement meter, and send it together with the number and position to the intelligent terminal of the corresponding technician. After receiving the calibration instruction, number and position through the intelligent terminal, the technician calibrates this displacement meter. If the ambient temperature value is less than or equal to the set ambient temperature threshold one, then measure this displacement meter three times again, and then take the average of the distances of each measuring point from the roadway surface and the surface displacements measured three times, and then substitute them into the regression formula.

[0031] Compared with the prior art, the beneficial effects of the present invention are:

[0032] 1. In the present invention, multi-point displacement meters are arranged at typical parts of the roadway surrounding rock. According to the displacements of different measuring points of the roadway surrounding rock measured by the multi-point displacement meters, the measured data are subjected to regression analysis according to the formula, and then the regression equation coefficients are substituted into the formula to obtain the surface displacement gradient values of each measuring point. Using the surface displacement gradient value as an evaluation index can better reflect the stability difference between the roadway floor and the rib.

[0033] 2. The present invention discriminates the stability of the deep soft rock roadway surrounding rock based on the secondary creep coefficient of the deep soft rock roadway surrounding rock, so as to facilitate the selection of reasonable support forms and parameters for the deep soft rock roadway. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] For the convenience of those skilled in the art to understand, the present invention will be further described below with reference to the accompanying drawings.

[0035] Figure 1 is the flow chart of the method of the present invention;

[0036] Figure 2 is the layout schematic diagram of the multi-point displacement meter of the present invention;

[0037] Figure 3 is the schematic diagram of the typical stress-strain curve of the surrounding rock of the present invention;

[0038] Figure 4This is a principle block diagram of the device of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Embodiment 1:

[0041] See also Figure 1 As shown, a deep surrounding rock stability evaluation support method comprises:

[0042] Drill holes at the locations to be measured in the deep soft rock corresponding to the tunnel, and arrange multiple displacement meters in the holes, such as Figure 2 As shown; in order to determine the thickness of the loosened zone of coal rock in a certain part of tunnel 1, a hole is drilled at that part, such as the section from point A to point B in the figure, and four measuring points C, D, E, and F of the multi-point displacement meter are arranged in the hole, among which the three measuring points C, D, and E are arranged within the loosened zone, and the other measuring point F is arranged in the original rock stress zone far away from the tunnel surface (generally more than 10.0m).

[0043] The anchor head 2 of the multi-point displacement meter is a claw-like metal component, which can be conveniently inserted into any position in the borehole and fixed to the borehole wall through the hole opening. Each measuring point corresponds to an anchor head, and is connected to the displacement recorder 4 of the multi-point displacement meter fixed at the hole opening through a steel wire rope 3. The displacement recorder 4 is connected to the data analyzer 5 through a data line. The data analyzer 5 is hung in a safe and secure place on both sides of the tunnel. The data analyzer 5 is used to analyze and display the thickness of the loose circle at this part at regular intervals (usually one day);

[0044] Since the measuring point F is located in the original rock stress zone, it can be considered that there is no displacement at the measuring point F. , and the displacement value of point A on the roadway surface is The elongation of the wire rope connecting point A and measuring point F can be Record: The elongation of the wire rope connecting point A and measuring point C , the displacement value of measuring point C is available Similarly, the displacement value of measuring point D can be obtained by using the displacement value of point A on the roadway surface. Elongation of the wire rope connecting point A and measuring point D The difference is shown as ; The displacement value of measuring point E can be used as the displacement value of point A on the roadway surface Elongation of the wire rope connecting point A and measuring point E The difference is shown as .

[0045] Record the distance r of each measuring point of the multi-point displacement meter from the roadway surface, and at the same time measure and record the surface displacement u of each measuring point through the multi-point displacement meter at regular intervals.

[0046] Substitute the distance r of each measuring point from the roadway surface and the surface displacement u into the regression formula , and obtain the values of the regression equation coefficients k0, k1, and k2; then substitute the values of the regression equation coefficients k1 and k2 into the formula to obtain the surface displacement gradient value λ of each measuring point; determine the critical allowable value of the displacement gradient λmin = 10.0 mm / m when the coal and rock of the roadway are in the critical state of loosening and fragmentation; use the formula to obtain the thickness L of the loosening zone. Generally, three to four measuring points of the multi-point displacement meter are arranged, one of which is located in the virgin rock stress area, and the rest are located in the coal and rock loosening zones. Thus, the thickness of the loosening zone measured in the project and its change with time, the displacements and displacement gradients of different measuring points and their changes with time can be obtained.

[0047] By estimating the thickness of the surrounding rock loosening zone, the thickness and swelling degree of the surrounding rock loosening zone in typical parts of the roadway show obvious non-uniform distribution. The thickness and swelling degree of the surrounding rock loosening zone in the roadway roof are not obvious; there are obvious loosening zone thickness and a certain degree of swelling in the arch baseline and the roadway sidewall of the roadway, and there is a certain loosening zone thickness and obvious swelling in the roadway floor. Considering the reinforcement effect of prestressed anchor bolts on the surrounding rock, the row and spacing of the anchor bolts and the length of the anchor bolts significantly affect the thickness of the surrounding rock loosening zone, the surface displacement gradient and the swelling degree of the surrounding rock of the roadway; without considering the reinforcement effect of prestressed anchor bolts on the surrounding rock, the row and spacing of the anchor bolts and the length of the anchor bolts have little influence on the thickness of the surrounding rock loosening zone in typical parts of the roadway, have a greater influence on the surface displacement gradient of the arch baseline and the roadway sidewall of the roadway, and have a certain influence on the surface displacement of the arch baseline and the roadway sidewall of the roadway; because the reinforcement of the surrounding rock by prestressed anchor bolts changes the mechanical properties of the surrounding rock, the thickness and swelling degree of the surrounding rock loosening zone are significantly reduced. The virgin rock stress significantly affects the thickness of the loosening zone, the surface displacement gradient and the surface displacement of each part of the roadway, especially has a more significant influence on the thickness of the loosening zone of the arch baseline and the roadway sidewall of the roadway and the surface displacement gradient of the roadway floor.

[0048] Analyze the characteristics of the deformation of the surrounding rock of the deep soft rock roadway with time, including the analysis of the primary creep characteristics of the surrounding rock and the analysis of the secondary creep characteristics of the surrounding rock.

[0049] The specific process of analyzing the primary creep characteristics of the surrounding rock is as follows:

[0050] Obtain the typical curve of the stress-strain of the surrounding rock under the action of triaxial confining pressure, such as Figure 3As shown in the figure, it is divided into four stages, namely the compaction stage OA of rock fractures under pressure, the elastic deformation stage AB of rock, the plastic stage BC of rock, and the dilatancy failure stage CD; the confining pressure and rock properties have a great influence on the peak pressure of surrounding rock, the deformation of surrounding rock after peak, and the residual strength. The surrounding rock of deep rock roadway in mine shows the characteristics of "soft rock". After the surrounding rock is compressed to the peak pressure, it will produce large deformation before failure and has large residual strength;

[0051] When the surrounding rock is in the plastic stage, it is assumed that the deformation of the surrounding rock in the plastic deformation zone can be assumed to be volume-incompressible. The roadway shape is circular, and the initial in-situ stress field is isotropic; the surrounding rock is a homogeneous and isotropic viscous medium, which conforms to the assumptions of continuum mechanics, and the medium in the plastic zone has incompressibility. According to the above assumptions, the strain state in the plastic zone can be expressed in polar coordinates as: ; Substitute and into the strain state in the plastic zone in polar coordinates and integrate; among them, is the tangential strain, is the radial strain, u1 is the radial deformation of the measuring point, mm, r1 is the distance from the measuring point to the roadway center, mm; the stress in the viscoelastic zone is expressed as: , ; where is the radial stress of the measuring point, MPa, is the tangential stress of the measuring point, MPa, is the viscosity coefficient, MPa / d, G is the shear modulus, MPa;

[0052] Most of the triaxial compressed coal and rock show shear failure and obey the Coulomb strength criterion. This criterion believes that the shear strength of rock [τ] that the rock can bear is determined by the rock cohesion c, the internal friction angle and the normal stress σ on the failure surface, that is, the shear strength of rock ;

[0053] The maximum shear stress on the failure surface is , τ1 is the maximum shear stress on the failure surface, σ1 is the maximum principal stress, and σ3 is the minimum principal stress; , kx is a constant, and its value is custom-defined according to the actual on-site conditions;

[0054] The boundary between the viscoelastic zone and the viscoplastic zone also satisfies , R is the radius of the plastic zone, , both a and b are coefficients, , from t = 0, , it is obtained that a + b = 0, that is , then , let the roadway radius be R0, then r = R0, and the change of the surrounding rock surface deformation with time is ;

[0055] Let , where A is the maximum deformation of the surrounding rock surface, , and B is the attenuation coefficient of the deformation velocity of the surrounding rock surface; , when , the stable value of the deformation of the surrounding rock surface is . Taking 0.95 times the stable value of the deformation of the surrounding rock surface as the primary creep action time of the surrounding rock, that is . At this time, the primary creep action time t = 3.0 / B. The attenuation coefficient B of the deformation velocity of the surrounding rock surface is determined by the shear modulus G and the viscosity coefficient . Its value is B = 0.1 - 0.2. Thus, the primary creep action time t = 15 - 30 days.

[0056] The analysis process of the secondary creep characteristics of the surrounding rock is as follows:

[0057] After the deformation of the surrounding rock undergoes primary creep, if the fragmentation condition is satisfied, the fragmentation of the surrounding rock will produce volumetric swelling and form secondary creep. The time point when the surrounding rock is in the secondary creep stage days, and the secondary creep stage of the surrounding rock is: , where A1 is the primary creep amount of the surrounding rock; A2 is the secondary creep amount of the surrounding rock, t0 is the primary creep action time of the surrounding rock, B1 is the attenuation coefficient of the primary creep velocity of the surrounding rock, and B2 is the attenuation coefficient of the secondary creep velocity of the surrounding rock.

[0058] Evaluating the stability of the surrounding rock of the deep soft rock roadway based on the attenuation coefficient of the secondary creep velocity of the surrounding rock. If only primary creep occurs without secondary creep, it is judged as an extremely stable state; if secondary creep occurs and the secondary creep attenuation coefficient B2 ≥ 0.05, it is judged as a stable state; if the secondary creep attenuation coefficient B2 ∈ [0.04, 0.05], it is judged as a basically stable state; if the secondary creep attenuation coefficient B2 < 0.04, it is judged as an unstable state; if the surrounding rock of the deep soft rock roadway only deforms within 5 to 10 days after excavation, that is, enters the accelerated deformation stage, it is judged as an extremely unstable state.

[0059] Selecting the support according to the stability of the surrounding rock of the deep soft rock roadway. If it is in an extremely stable state or a stable state, no operation is carried out; if it is in an unstable state, timely secondary support is carried out on the surrounding rock of the deep soft rock roadway and the support strength is enhanced; if it is in an extremely unstable state, a new support design is carried out for the surrounding rock of the deep soft rock roadway; among them, the secondary support is to arrange prestressed anchor cables at the corresponding positions. The length of the anchor cable is CM = L + (0.5 m - 1.0 m), and in the part where the thickness of the loose circle L < 2.5 m, prestressed anchor bolts are arranged. The length of the anchor bolt CG is determined according to the thickness of the loose circle L, specifically CG = L + (0.3 m - 0.5 m). Finally, the row spacing of the anchor cables and the row spacing of the anchor bolts are adjusted.

[0060] Example 2:

[0061] Please refer to Figure 4 As shown, a support device for evaluating the stability of deep surrounding rock is used to implement the above-mentioned method for evaluating the stability of deep surrounding rock, and includes a server. A data acquisition unit, a data analysis unit, a surrounding rock analysis unit, a stability evaluation unit, and a support selection unit are provided in the server;

[0062] The data acquisition unit records the distance of each measuring point of the multi-point displacement meter from the roadway surface, and at the same time measures and records the surface displacement of each measuring point through the multi-point displacement meter at regular intervals; the data analysis unit analyzes the distance of each measuring point from the roadway surface and the surface displacement, and outputs the surface displacement gradient value and the thickness of the loosening circle of each measuring point; the surrounding rock analysis unit analyzes the characteristics of the deformation of the surrounding rock of the deep soft rock roadway over time, and outputs the attenuation coefficient of the primary creep speed of the surrounding rock and the attenuation coefficient of the secondary creep speed of the surrounding rock; the stability evaluation unit evaluates the stability of the surrounding rock of the deep soft rock roadway based on the attenuation coefficient of the secondary creep speed of the surrounding rock; the support selection unit selects the support according to the stability of the surrounding rock of the deep soft rock roadway.

[0063] Example 3:

[0064] Based on Example 2, a data calibration unit is further included in the server;

[0065] The data calibration unit collects and analyzes and calibrates the displacement meter information of the borehole displacement meter corresponding to the deep soft rock. Among them, the displacement meter information includes the number, position, density data, and measurement environmental conditions; the density data is composed of the propagation speed and attenuation degree measured by ultrasonic waves in the grouting hole where the displacement meter is located by ultrasonic equipment; the measurement environmental conditions include the environmental temperature and humidity where the displacement meter is located; the specific analysis process is as follows:

[0066] Analyze the density data, perform normalization processing on the propagation speed and attenuation degree, and take their values, which are marked as Vs1 and Vs2 in turn; set the weight factors of the propagation speed and attenuation degree as Vk1 and Vk2; substitute the values of the propagation speed and attenuation degree into the preset density calculation model MSz = Vs1×Vk1 + 2 / (Vs2×Vk2 + 1) to obtain the density value MSz; compare the density value with the set density threshold. If the density value is less than the density threshold, mark the displacement data measured by the corresponding displacement meter and the distance of the measuring point from the roadway surface and the surface displacement as invalid data, and at the same time generate a re-grouting instruction for the displacement meter, and send the number, position, and re-grouting instruction of the displacement meter to the intelligent terminal of the corresponding preset processing personnel. After receiving the number, position, and re-grouting instruction of the displacement meter through the intelligent terminal, the preset processing personnel perform re-grouting processing on the displacement meter; if the density value is greater than or equal to the density threshold, analyze the environmental conditions during measurement, specifically:

[0067] Sort all the ambient temperatures in the order of collection time, and set three temperature ranges, namely high temperature range, normal range and low temperature range; match all the ambient temperatures with the three temperature ranges, mark the ambient temperatures in the high temperature range as ultra-high temperatures, count the number of ultra-high temperatures to get the ultra-high number, calculate the average value and the maximum value of all ultra-high temperatures and mark them as high average value and high maximum value; extract the values of the ultra-high number, high average value and high maximum value and input them into the computer, construct a rhombus with line segments of the lengths corresponding to the ultra-high number and high average value, select the center point of the rhombus, take the line segment corresponding to the high maximum value as the height of the rhombus with the center point of the rhombus as the starting point, construct a quadrangular pyramid with the rhombus and the height, extract the volume of the quadrangular pyramid and mark the value of the volume as the ultra-temperature shadow value; mark the ambient temperatures in the low temperature range as low zone temperatures; sort the low zone temperatures in the order of time, calculate the time duration between two adjacent low zone temperatures to get the low interval duration, calculate the average value of all the low interval duration values to get the low time average value; count the number of low zone temperatures to get the low zone number; sum up all the low zone temperatures and take the average value to get the low zone average value; perform normalization processing on the low time average value, low zone number and low zone average value and take the normalized values of the three, and mark them as DS1, DS2 and DS3 in turn; substitute them into the preset low temperature model to obtain the low temperature shadow value DW, where are all preset weight factors, and the values can be 0.3, 0.3 and 0.4; customize the weight ratios of the low temperature shadow value and the ultra-temperature shadow value, such as 0.4 and 0.6; multiply the low temperature shadow value and the ultra-temperature shadow value by the corresponding weight ratios respectively to achieve weighted calculation, and then sum them up to output the ambient temperature value; if the ambient temperature value is greater than the set ambient temperature threshold one and less than or equal to the ambient temperature threshold two, then convert the ambient temperature value into a calibration deviation value according to a certain ratio, where the ambient temperature value is proportional to the calibration deviation value, and the larger the ambient temperature value, the larger the calibration deviation value, and then match the calibration deviation value with several preset deviation ranges, and each deviation range corresponds to a distance from the measuring point to the roadway surface and a compensation number for surface displacement; if the calibration deviation value is within the deviation range, add the distances from the measuring points corresponding to the deviation range to the roadway surface and the compensation numbers for surface displacement to the distances r from the measuring points to the roadway surface and the surface displacements u respectively, and then substitute them into the regression formula; if the ambient temperature value is greater than the ambient temperature threshold two, generate a calibration instruction for the displacement meter and send it to the intelligent terminal of the corresponding technician together with the number and position, and after receiving the calibration instruction, number and position through the intelligent terminal, the technician calibrates the displacement meter; if the ambient temperature value is less than or equal to the set ambient temperature threshold one, then measure the displacement meter three times again, then take the average value of the distances from the measuring points to the roadway surface and the surface displacements measured three times, and then substitute them into the regression formula.

[0068] The present invention analyzes and calibrates the displacement gauge information of the borehole displacement gauge corresponding to deep soft rock roadway, making the substituted data more accurate, avoiding inaccurate data measured by the displacement gauge, resulting in deviation in the calculated creep rate attenuation coefficient and affecting the determination result.

[0069] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all details in detail, nor do they limit the invention to only the specific embodiments. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A support method for evaluating the stability of deep surrounding rocks, characterized in that, The method includes: Step 1: Drill holes at the parts to be measured in the roadway corresponding to deep soft rock, and arrange multi-point displacement gauges in the holes. Record the distance r of each measuring point of the multi-point displacement gauge from the roadway surface. At the same time, measure and record the surface displacement u of each measuring point at regular intervals through the multi-point displacement gauge. Step 2: Substitute the distance r of each measurement point from the roadway surface and the surface displacement u into the regression formula , and obtain the values of the regression equation coefficients k0, k1, and k2; then substitute the values of the regression equation coefficients k1 and k2 into the formula to obtain the surface displacement gradient value λ of each measurement point; determine the critical allowable value of the displacement gradient λmin = 10.0 mm / m when the roadway coal and rock are in the critical state of loosening and fragmentation; use the formula to obtain the thickness L of the loose zone; Step 3: Analyze the characteristics of the surrounding rock deformation of the deep soft rock roadway changing with time, including the analysis of the primary creep characteristics of the surrounding rock and the analysis of the secondary creep characteristics of the surrounding rock, so as to obtain the primary creep speed attenuation coefficient B1 of the surrounding rock and the secondary creep speed attenuation coefficient B2 of the surrounding rock. Step 4: Evaluate the stability of the surrounding rock of the deep soft rock roadway with the secondary creep speed attenuation coefficient of the surrounding rock. Among them, the classification of the stability of the surrounding rock of the deep soft rock roadway includes extremely stable state, stable state, basically stable state, unstable state and extremely unstable state. Step 5: Select the support according to the stability of the surrounding rock of the deep soft rock roadway. If it is in an extremely stable state or a stable state, no operation is carried out. If it is in an unstable state, timely secondary support is carried out on the surrounding rock of the deep soft rock roadway, and the support strength is strengthened. If it is in an extremely unstable state, a re-support design is carried out on the surrounding rock of the deep soft rock roadway. The secondary support is to arrange prestressed anchor cables at the corresponding positions. The length of the anchor cable is CM = L + (0.5 m to 1.0 m). And in the part where the thickness of the loose circle L < 2.5 m, prestressed bolts are arranged. The length of the bolt CG is determined according to the thickness of the loose circle L, specifically CG = L + (0.3 m to 0.5 m). Finally, adjust the row spacing of the anchor cables and the row spacing of the bolts. It also includes collecting and analyzing and calibrating the displacement gauge information of the displacement gauges in the holes of the roadway corresponding to deep soft rock. Among them, the displacement gauge information includes number, position, density data and measurement environmental conditions. The specific analysis process is as follows: Analyze the density data, normalize the propagation speed and attenuation degree, and take the values of both, and substitute them into the preset density calculation model to obtain the density value. Compare the density value with the set density threshold. If the density value is less than the density threshold, mark the displacement data measured by the corresponding displacement gauge as invalid data for the distance of the measuring point from the roadway surface and the surface displacement, and at the same time generate a re-injection instruction for the displacement gauge, and send the number, position and re-injection instruction of the displacement gauge to the intelligent terminal of the corresponding preset processing personnel. After receiving the number, position and re-injection instruction of the displacement gauge through the intelligent terminal, the preset processing personnel carry out re-grouting treatment on the displacement gauge. If the density value is greater than or equal to the density threshold, analyze the environmental conditions during measurement. Specifically: Sort all the ambient temperatures in the order of collection time, and set three temperature ranges, namely the high-temperature range, the normal range, and the low-temperature range; match all the ambient temperatures with the three temperature ranges, mark the ambient temperatures in the high-temperature range as ultra-high temperatures, count the number of ultra-high temperatures to obtain the ultra-high number, calculate the average value and the maximum value of all ultra-high temperatures and mark them as the high average value and the high maximum value; extract the numerical values of the ultra-high number, the high average value, and the high maximum value and input them into the computer, construct a rhombus with line segments of the lengths corresponding to the ultra-high number and the high average value, select the center point of the rhombus, take the center point of the rhombus as the starting point, use the line segment corresponding to the high maximum value as the height of the rhombus, construct a quadrangular pyramid with the rhombus and the height, extract the volume of the quadrangular pyramid and mark the numerical value of the volume as the over-temperature shadow value; mark the ambient temperatures in the low-temperature range as low-region temperatures; sort the low-region temperatures in the order of time, calculate the time duration between two adjacent low-region temperatures to obtain the low-interval duration, calculate the average value of all the low-interval duration numerical values to obtain the low-time average value; count the number of low-region temperatures to obtain the low-region number; sum up all the low-region temperatures and take the average value to obtain the low-region average value; perform normalization processing on the low-time average value, the low-region number, and the low-region average value and take the numerical values after the normalization processing of the three, substitute them into the preset low-temperature model to obtain the low-temperature shadow value; multiply the low-temperature shadow value and the over-temperature shadow value by their corresponding weight ratios respectively, and then sum them to output the ambient temperature value; if the ambient temperature value is greater than the set ambient temperature threshold one and less than or equal to the ambient temperature threshold two, then convert the ambient temperature value into a calibration deviation value according to a certain ratio, and then match the calibration deviation value with several preset deviation ranges, and each deviation range corresponds to a distance from the measuring point to the roadway surface and a compensation number for the surface displacement; if the calibration deviation value is within the deviation range, then add the distance from each measuring point to the roadway surface and the compensation number for the surface displacement corresponding to the deviation range to the distance r from each measuring point to the roadway surface and the surface displacement u respectively, and then substitute them into the regression formula; if the ambient temperature value is greater than the ambient temperature threshold two, then generate a calibration instruction for the displacement meter and send it, along with the number and the position, to the intelligent terminal of the corresponding technician. After receiving the calibration instruction, the number, and the position through the intelligent terminal, the technician calibrates the displacement meter; if the ambient temperature value is less than or equal to the set ambient temperature threshold one, then measure the displacement meter three times again, then take the average value of the distances from each measuring point to the roadway surface and the surface displacements measured three times, and then substitute them into the regression formula.

2. The support method for evaluating the stability of deep surrounding rock according to claim 1, characterized in that, The specific process of analyzing the primary creep characteristics of the surrounding rock is as follows: Obtain the typical curve of the surrounding rock stress and strain under the action of triaxial confining pressure of the rock, and divide it into four stages, namely the compaction stage OA of the rock fissures under pressure, the elastic deformation stage AB of the rock, the plastic stage BC of the rock, and the dilatancy failure stage CD; When in the plastic stage, it is assumed that the deformation of the surrounding rock in the plastic deformation zone is volume-incompressible, the roadway shape is circular, the initial in-situ stress field is isotropic, the surrounding rock is a homogeneous and isotropic viscoelastic medium, which conforms to the assumptions of continuum mechanics. Since there is incompressibility in the plastic zone medium, the strain state in the plastic zone is expressed in polar coordinates as follows: ; Substitute and into the strain state in the plastic zone expressed in polar coordinates and integrate; where is the tangential strain, is the radial strain, u1 is the radial deformation of the measuring point, and r1 is the distance from the measuring point to the roadway center; the stress in the viscoelastic zone is expressed as: , ; where is the radial stress of the measuring point, is the tangential stress of the measuring point, is the viscosity coefficient, and G is the shear modulus; The shear strength of rock [τ] that the rock can bear is determined by the cohesion c of the rock, the internal friction angle and the normal stress σ on the failure plane, that is, the shear strength of the rock ; The maximum shear stress on the failure surface is , where τ1 is the maximum shear stress on the failure surface, is the maximum principal stress, is the minimum principal stress; , where kx is a constant, and its value is custom-defined according to the actual on-site conditions; The boundary between the viscoelastic region and the viscoplastic region also satisfies , where R is the radius of the plastic zone, , and both a and b are coefficients, , at t = 0, , we get a + b = 0, that is , then , let the radius of the roadway be R0, then r = R0, and the change of the surrounding rock surface deformation with time is ; Let , A be the maximum deformation of the surrounding rock surface, , B be the attenuation coefficient of the deformation rate of the surrounding rock surface; , when , the stable value of the deformation of the surrounding rock surface is , taking 0.95 times the stable value of the deformation of the surrounding rock surface as the primary creep action time of the surrounding rock, that is , at this time the primary creep action time t = 3.0 / B, and the attenuation coefficient B of the deformation rate of the surrounding rock surface is determined by the shear modulus G and the viscosity coefficient , and its value is B = 0.1 - 0.

2. Thus, the primary creep action time t = 15 - 30 days.

3. A support method for evaluating the stability of deep surrounding rocks according to claim 2, characterized in that The analysis process of the secondary creep characteristics of the surrounding rock is as follows: After the surrounding rock deformation undergoes primary creep, if the fragmentation condition is met, the fragmentation of the surrounding rock will produce volumetric dilatancy, resulting in secondary creep. The time point when the surrounding rock is in the secondary creep stage days, the secondary creep stage of the surrounding rock is: , where A1 is the primary creep displacement of the surrounding rock; A2 is the secondary creep displacement of the surrounding rock, t0 is the action time of primary creep of the surrounding rock, B1 is the primary creep velocity attenuation coefficient of the surrounding rock, and B2 is the secondary creep velocity attenuation coefficient of the surrounding rock.

4. A support method for evaluating the stability of deep surrounding rocks according to claim 3, characterized in that, The specific evaluation process for evaluating the stability of the surrounding rock of deep soft rock roadways using the attenuation coefficient of the secondary creep rate of the surrounding rock is as follows: If only primary creep occurs and no secondary creep occurs, it is judged to be in an extremely stable state; if secondary creep occurs and the secondary creep attenuation coefficient B2 ≥ 0.05, it is judged to be in a stable state; if the secondary creep attenuation coefficient B2 ∈ [0.04, 0.05], it is judged to be in a basically stable state; if the secondary creep attenuation coefficient B2 < 0.04, it is judged to be in an unstable state; if the surrounding rock of the deep soft rock roadway deforms only within 5 to 10 days after excavation, that is, enters the accelerated deformation stage, it is judged to be in an extremely unstable state.

5. A support device for evaluating the stability of deep surrounding rocks, characterized in that Applied to implement a deep surrounding rock stability evaluation and support method according to any one of claims 1-4, including: A data acquisition unit that records the distances of each measuring point of the multi-point displacement meter from the roadway surface, and at the same time measures and records the surface displacements of each measuring point through the multi-point displacement meter at regular intervals. A data analysis unit that analyzes the distances of each measuring point from the roadway surface and the surface displacements, and outputs the surface displacement gradient values and loosening circle thicknesses of each measuring point. A surrounding rock analysis unit that analyzes the characteristics of the deformation of the surrounding rock of the deep soft rock roadway over time, and outputs the primary creep rate attenuation coefficient and secondary creep rate attenuation coefficient of the surrounding rock. A stability evaluation unit that evaluates the stability of the surrounding rock of the deep soft rock roadway using the secondary creep rate attenuation coefficient of the surrounding rock. A support selection unit that selects a support according to the stability of the surrounding rock of the deep soft rock roadway.

6. The support device for evaluating the stability of deep surrounding rocks according to claim 5, characterized in that, It further includes: A data calibration unit that is used to collect the displacement meter information of the in-hole displacement meter corresponding to the deep soft rock roadway and perform analysis and calibration.

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