An in-situ direct shear test automatic control system and method for rock mass

Abstract

The present invention provides an automatic control system and method for in-situ direct shear test of rock mass, including a specimen normal loading unit, a specimen horizontal loading unit, a specimen normal data acquisition and pressure control unit, a specimen horizontal data acquisition and pressure control unit, and a main control terminal machine. The automatic control system and method for in-situ direct shear test of rock mass provided by the present invention, by using test equipment such as a main control terminal machine, an electronic dial gauge, an oil pressure sensor, an electric oil pressure pump, etc., according to the clear peak strength prediction standard formula, the encryption discrimination standard before the horizontal shear stress reaches the peak strength, the actual peak strength quantization discrimination formula of the horizontal stress during the test process, and the boundary conditions, realizes the automatic control process of the in-situ direct shear test of rock mass according to the specific execution steps of the automatic program, eliminates the cumbersome labor of personnel, and improves the test efficiency and the degree of test automation.

Description

Technical Field

[0001] The present invention is applicable to the technical field of in-situ measurement of engineering geology such as hydropower, water conservancy, transportation, geological disaster prevention and control, mines, etc., and specifically relates to an automatic control system and method for in-situ direct shear test of rock masses. Background Art

[0002] For engineering geological investigation and design, it is necessary to obtain the shear strength parameters of rock masses in the engineering area. The in-situ shear test of rock masses on site is the most direct, accurate and closest to the actual working conditions method to obtain the shear strength parameters of rock masses.

[0003] In the traditional in-situ direct shear test of rock masses, the test personnel control the hydraulic oil pump and jack, so as to apply normal stress and horizontal shear stress to the test piece, and the specialized test personnel read the values of normal stress, horizontal shear stress and displacement, etc. Since the test is generally carried out in the exploration adit, the humid, dusty and muddy environment of the adit and the poor lighting facilities and other factors all affect the reliability and accuracy of the results of the in-situ direct shear test of rock masses. Summary of the Invention

[0004] Aiming at the defects existing in the prior art, the present invention provides an automatic control system and method for in-situ direct shear test of rock masses, which can effectively solve the above problems.

[0005] The technical solution adopted by the present invention is as follows:

[0006] The present invention provides an automatic control system for in-situ direct shear test of rock masses, including a test piece normal loading unit (1), a test piece horizontal loading unit (2), a test piece normal data acquisition and pressure control unit (3), a test piece horizontal data acquisition and pressure control unit (4) and a main control terminal machine (5);

[0007] The test piece normal loading unit (1) is arranged between the top surface of the rock mass test piece (6) and the upper mortar (7) directly above it, and is used to apply normal stress to the top surface of the rock mass test piece (6);

[0008] The test piece horizontal loading unit (2) is arranged between the side wall of the rock mass test piece (6) and the side mortar (8) on its side, and is used to apply horizontal stress to the side wall of the rock mass test piece (6);

[0009] The test piece normal data acquisition and pressure control unit (3) is connected to the test piece normal loading unit (1), and is used to control the normal stress value applied by the test piece normal loading unit (1) to the top surface of the rock mass test piece (6), and collect the normal stress value and the normal displacement of the rock mass test piece (6);

[0010] The horizontal data acquisition and pressure control unit (4) of the test piece is connected to the horizontal loading unit (2) of the test piece, and is used to control the horizontal stress value applied by the horizontal loading unit (2) of the test piece to the side wall of the rock mass test piece (6), and collect the horizontal stress value and the horizontal displacement of the rock mass test piece (6).

[0011] The main control terminal (5) is respectively connected to the normal data acquisition and pressure control unit (3) and the horizontal data acquisition and pressure control unit (4) of the test piece, and is used to obtain in real time the normal stress value, the horizontal stress value, the normal displacement of the rock mass test piece (6) and the horizontal displacement of the rock mass test piece (6) in the in-situ direct shear test of the rock mass, and control the pressure control units in the normal data acquisition and pressure control unit (3) and the horizontal data acquisition and pressure control unit (4) of the test piece.

[0012] Preferably, the normal loading unit (1) of the test piece includes a roller row (1-1), a first steel backing plate (1-2), a first hydraulic jack (1-3) and a force transfer column (1-4);

[0013] Between the top surface of the rock mass test piece (6) and the upper mortar (7) directly above it, in the order from bottom to top, the roller row (1-1), the first steel backing plate (1-2), the first hydraulic jack (1-3) and the force transfer column (1-4) are arranged in sequence, and the bottom of the force transfer column (1-4) is clamped and connected to the top surface of the first hydraulic jack (1-3), and the top of the force transfer column (1-4) is in close contact with the upper mortar (7).

[0014] Preferably, the top surface of the rock mass test piece (6), the roller row (1-1), the first steel backing plate (1-2), the first hydraulic jack (1-3) and the force transfer column (1-4) are coaxially arranged; and the cross-sections of the roller row (1-1) and the first steel backing plate (1-2) are the same, smaller than the top surface of the rock mass test piece (6) and larger than the cross-section of the first hydraulic jack (1-3).

[0015] Preferably, the normal data acquisition and pressure control unit (3) of the test piece includes a first electric oil pump (3-1), a first oil pressure sensor (3-2), a first DC battery pack (3-3), the inlet and return oil pipes (3-4) of the first electric oil pump, the inlet and return oil nozzles (3-5) of the first electric oil pump and a normal displacement acquisition device (3-6);

[0016] The inlet and return oil pipe (3-4) of the first electric oil pump is connected to the inlet and return oil nozzle (3-5) of the first electric oil pump of the first hydraulic jack (1-3) to control the normal stress value applied by the first hydraulic jack (1-3).

[0017] The first oil pressure sensor (3-2) is used to collect the normal stress value in real time.

[0018] The first DC battery pack (3-3) is used to supply power to the first electric oil pump (3-1).

[0019] The normal displacement acquisition device (3-6) is used to collect the normal displacement of the rock mass specimen (6) in real time.

[0020] Preferably, the specimen horizontal loading unit (2) includes a second steel backing plate (2-1), a thrust steel backing plate (2-2) and a second hydraulic jack (2-3).

[0021] The second hydraulic jack (2-3) is horizontally arranged, and its axis and the bottom surface of the rock mass specimen (6) are on the same horizontal plane; the base of the second hydraulic jack (2-3) abuts against the side mortar (8), and the thrust steel backing plate (2-2) and the second steel backing plate (2-1) are sequentially arranged between the output end of the second hydraulic jack (2-3) and the side wall of the rock mass specimen (6).

[0022] Preferably, the second steel backing plate (2-1) is attached to the side wall of the rock mass specimen (6) and has the same height as the side wall of the rock mass specimen (6), completely covering the side wall of the rock mass specimen ().

[0023] The height of the thrust steel backing plate (2-2) is lower than the height of the second steel backing plate (2-1), and the bottom surface of the thrust steel backing plate (2-2) and the bottom surface of the rock mass specimen (6) are on the same horizontal plane.

[0024] Therefore, the output end of the second hydraulic jack (2-3), the thrust steel backing plate (2-2) and the second steel backing plate (2-1) are in a stepped form with gradually increasing top surface height.

[0025] Preferably, the specimen horizontal data acquisition and pressure control unit (4) includes a second electric oil pump (4-1), a second oil pressure sensor (4-2), a second DC battery pack (4-3), the inlet and return oil pipe (4-4) of the second electric oil pump, the inlet and return oil nozzle (4-5) of the second electric oil pump and a horizontal displacement acquisition device (4-6).

[0026] The inlet and return oil pipe (4-4) of the second electric oil pump (4-1) is connected to the inlet and return oil nozzle (4-5) of the second electric oil pump of the second hydraulic jack (2-3) for controlling the horizontal stress value applied by the second hydraulic jack (2-3).

[0027] The second oil pressure sensor (4-2) is used to collect the horizontal stress value in real time.

[0028] The second DC battery pack (4-3) is used to supply power to the second electric oil pump (4-1).

[0029] The horizontal displacement acquisition device (4-6) is used to collect the horizontal displacement of the rock mass specimen (6) in real time.

[0030] The present invention also provides a method for an automatic control system of the in-situ direct shear test of rock mass, including the following steps:

[0031] Step S1: Confirm the installation of equipment and the state of the measurement system.

[0032] Step S2: Preparation before the test: Select the test type, including the in-situ direct shear test of rock mass and the friction test of the in-situ direct shear test of rock mass.

[0033] Step S3: Input key parameters: In this test, the constant normal stress value σ yu , the shear area of the specimen, the shear angle, the output force coefficients of the normal and shear direction jacks; Using formula (1), obtain the predicted value τ max :

[0034] τ max = kσ yu (1)

[0035] Where: k is the prediction coefficient, determined according to the test type; If it is an in-situ direct shear test of rock mass, k takes 1.5; If it is a friction test of the in-situ direct shear test of rock mass, k takes 1.

[0036] Step S4: Confirm key parameters and start the test.

[0037] Step S5: According to the set key parameters, control the normal loading unit (1) of the specimen to apply a constant normal stress to the top surface of the rock mass specimen (6), and the normal stress value is σ yu ;

[0038] Step S6: Judge the stability of the normal stress. When the normal stress is stable, execute Step S7.

[0039] Step S7, control the horizontal loading unit (2) of the test piece, so as to apply horizontal shear stress to the side wall of the rock mass test piece (6). The specific control method for applying the horizontal shear stress is as follows:

[0040] Step S7.1, adopt formula (2), and apply the horizontal shear stress step by step with a step difference of 1 / 10 of the estimated value τ max of the peak value of the horizontal shear stress, and judge stability at the same time. Meanwhile, collect the horizontal shear stress and shear displacement in real time, and generate a horizontal shear stress-shear displacement curve in real time;

[0041]

[0042] where: τ n is the nth-level horizontal shear stress; τ n-1 is the (n - 1)th-level horizontal shear stress; n is the number of levels, starting from 1 and increasing. When n = 1, τ n-1 = τ0 = 0; Δτ n is the step difference between the nth-level and the (n - 1)th-level horizontal shear stresses;

[0043] Step S7.2, during the process of applying the horizontal shear stress step by step in the manner of Step S7.1, judge in real time whether the increment of the shear displacement at this level reaches 1.5 times the increment of the shear displacement at the previous level, that is, judge whether formula (3) holds:

[0044] Δs n = 1.5Δs n-1 (3)

[0045] where:

[0046] Δs n is the increment of the nth-level shear displacement, that is, the increment of the shear displacement at this level; Δs n-1 is the increment of the (n - 1)th-level shear displacement, that is, the increment of the shear displacement at the previous level;

[0047] If formula (3) does not hold, continue to execute Step S7.1; if formula (3) holds, execute Step S7.3;

[0048] Step S7.3, starting from applying the horizontal shear stress at the (n + 1)th level, halve the step difference, that is, obtain a new step difference according to the manner of formula (4), and then apply the horizontal shear stress step by step with the new step difference and judge stability;

[0049]

[0050] where: τ n+1 is the (n + 1)th-level horizontal shear stress; Δτ n+1 is the step difference between the (n + 1)th-level and the nth-level horizontal shear stresses, which is the new step difference;

[0051] Step S7.4, during the process of applying the horizontal shear stress step by step with a new differential, if before reaching the horizontal shear peak stress determined in step S8, the shear displacement increment at this level increases again to 1.5 times the shear displacement increment at the previous level, then the horizontal shear stress increment applied at the next level is halved compared to the horizontal shear stress increment applied at this level, until the horizontal shear stress increment is less than 0.1 Mpa, and step S7.5 is executed;

[0052] The formula is:

[0053] When Δs n+m = 1.5Δs n+m-1 then

[0054] where:

[0055] Δs n+m is the shear displacement increment at the n + m level;

[0056] Δs n+m-1 is the shear displacement increment at the n + m - 1 level;

[0057] Δτ n+m+1 is the horizontal shear stress increment at the n + m + 1 level;

[0058] Δτ n+m is the horizontal shear stress increment at the n + m level;

[0059] τ n+m+1 is the horizontal shear stress at the n + m + 1 level;

[0060] τ n+m is the horizontal shear stress at the n + m level;

[0061] Step S7.5, assuming that the horizontal shear stress increment Δτ n+x < 0.1 Mpa at the n + x level, then the horizontal shear stress increment Δτ n+x+1 = 0.1 Mpa at the n + x + 1 level. Therefore, the horizontal shear stress τ n+x+1 = τ n+x + 0.1 MPa, where τ n+x is the horizontal shear stress at the n + x level; then apply the horizontal shear stress step by step with a differential of 0.1 Mpa, that is, the new differential is 0.1 Mpa at this time, until the horizontal shear peak stress determined in step S8 appears;

[0062] Step S8, during the process of applying the horizontal shear stress in the manner of step S7, the criterion for determining the horizontal shear peak stress is:

[0063] (1) If the test piece belongs to the rock mass type that undergoes brittle shear failure: the current-level horizontal shear stress is lower than the upper-level horizontal shear stress, the upper-level horizontal shear stress is higher than the upper-upper-level horizontal shear stress, and the value reduction of the current-level horizontal shear stress is 2 times or more of the value increase of the upper-level horizontal shear stress, then it is determined that the upper-level horizontal shear stress is the horizontal shear peak stress;

[0064] (2) If the test piece belongs to the rock mass type that undergoes plastic shear failure: within any 60s interval, the horizontal shear stress fluctuates within a certain range, and the fluctuation range is ±0.05MPa, then it is determined that the average value of the horizontal shear stress during this period is the horizontal shear peak stress;

[0065] (3) If the test piece for the direct shear test does not belong to the rock mass type that undergoes brittle shear failure and the rock mass type that undergoes plastic shear failure, then when the total horizontal shear displacement reaches 15mm, the average value of a total of 5 levels of shear data of the maximum horizontal shear stress within 15mm before and after is used as the horizontal shear peak stress;

[0066] Step S9, after obtaining the horizontal shear peak stress through step S8, when applying the horizontal shear stress in the subsequent test, it is controlled by shear displacement. The horizontal shear stress-shear displacement data is recorded every time the shear displacement increases by 0.50mm until the total shear displacement exceeds 35mm, and the test ends.

[0067] The automatic control system and method for in-situ direct shear test of rock mass provided by the present invention have the following advantages:

[0068] The automatic control system and method for in-situ direct shear test of rock mass provided by the present invention, by using test equipment such as a main control terminal machine, an electronic dial gauge, an oil pressure sensor, an electric oil pump, etc., according to the clear peak strength prediction standard formula, the encryption discrimination standard before the horizontal shear stress reaches the peak strength, the actual peak strength quantization discrimination formula of the horizontal stress during the test process and the boundary conditions, and in accordance with the specific execution steps of the automatic program, realizes the automatic control process of the in-situ direct shear test of rock mass, saves the cumbersome labor of personnel, and improves the test efficiency and the degree of test automation. Description of the Drawings

[0069] Figure 1 It is the overall diagram of the automatic control system for in-situ direct shear test of rock mass provided by the present invention;

[0070] Figure 2 It is the schematic diagram of the installation positions of the normal electronic dial gauge and the horizontal electronic dial gauge provided by the present invention;

[0071] Figure 3 It is the flow chart of the automatic control method for in-situ direct shear test of rock mass provided by the present invention;

[0072] Figure 4 Schematic diagram of stress-strain relationship of brittle shear failure of the test piece in the in-situ direct shear test automatic control method provided by the present invention

[0073] Figure 5 Schematic diagram of stress-strain relationship of plastic shear of the test piece in the in-situ direct shear test automatic control method provided by the present invention

[0074] Wherein:

[0075] Test piece normal loading unit 1; Test piece horizontal loading unit 2; Test piece normal data acquisition and pressure control unit 3; Test piece horizontal data acquisition and pressure control unit 4; Main control terminal 5; Rock mass test piece 6; Upper mortar 7; Side mortar 8; Reinforced concrete protective shell 9; Displacement measurement mark 10; Force diagram 11

[0076] Roller row 1-1; First steel backing plate 1-2; First hydraulic jack 1-3; Force transfer column 1-4; Second steel backing plate 2-1; Thrust steel backing plate 2-2; Second hydraulic jack 2-3; First electric oil pump 3-1; First oil pressure sensor 3-2; First DC battery pack 3-3; Inlet and return oil pipes of the first electric oil pump 3-4; Inlet and return oil nozzles of the first electric oil pump 3-5; Normal displacement acquisition device 3-6; Second electric oil pump 4-1; Second oil pressure sensor 4-2; Second DC battery pack 4-3; Inlet and return oil pipes of the second electric oil pump 4-4; Inlet and return oil nozzles of the second electric oil pump 4-5; Horizontal displacement acquisition device 4-6

[0077] First normal electronic dial gauge A1; Second normal electronic dial gauge A2; Third normal electronic dial gauge A3; Fourth normal electronic dial gauge A4; First horizontal electronic dial gauge B1; Second horizontal electronic dial gauge B2; Third horizontal electronic dial gauge B3; Fourth horizontal electronic dial gauge B4 Detailed implementation manners

[0078] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention

[0079] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "upper end", "lower end", "outside", "both ends", "middle", "bottom", etc. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or device referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention

[0080] In the present invention, unless otherwise clearly specified and defined, terms such as "arrangement", "installation", "provided with", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, a direct connection, or an indirect connection through an intermediate medium. It may be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0081] The present invention discloses an automatic control system and method for in-situ direct shear test of rock mass. This method clarifies the specific parameters and functions of the test equipment for the automatic control of in-situ direct shear test of rock mass, quantifies the standard formula for predicting the peak strength of horizontal shear stress, gives the encryption discrimination criterion before the horizontal shear stress reaches the peak strength, proposes the actual peak strength quantification discrimination formula and boundary conditions of horizontal shear stress during the test process, details the specific execution steps of the automatic program, and gives the complete automatic control process and the whole process method of in-situ direct shear test of rock mass. The present invention is applicable to the technical field of in-situ measurement of engineering geology such as hydropower, water conservancy, transportation, geological disaster prevention and control, mines, etc., especially the in-situ direct shear test work of rock mass at the site of engineering geological investigation.

[0082] The automatic control process and method proposed by the present invention solve a series of problems in the traditional in-situ direct shear test of rock mass, such as the need for test personnel to apply normal stress and horizontal shear stress to the test piece through a hydraulic oil pump and a jack, the need for a special person to monitor the normal stress pressure gauge during the shear process, and the need to invest 4 - 6 test personnel to read and record the normal and horizontal stress values and displacement values at all times, which have problems such as a large number of personnel occupied, low efficiency, and great human influence factors.

[0083] The following further describes the present invention in conjunction with the drawings and specific embodiments.

[0084] The present invention provides an automatic control system and method for in-situ direct shear test of rock mass, quantifies the peak prediction formula of horizontal shear stress, gives the encryption discrimination criterion before the horizontal shear stress reaches the peak strength, proposes the actual peak strength quantification discrimination formula and boundary conditions of horizontal shear stress during the test process, details the specific execution steps of the automatic program, and gives the complete automatic control process and the whole process method of in-situ direct shear test of rock mass. By using the automatic control system and method for in-situ direct shear test of rock mass provided by the present invention, through the communication between the main control terminal 5 and the test piece normal data acquisition and pressure control unit 3 and the test piece horizontal data acquisition and pressure control unit 4, the in-situ direct shear test of rock mass can be carried out efficiently and accurately, and the reliability and accuracy of the in-situ direct shear test of rock mass can be improved.

[0085] The detailed technical solution of the present invention is as follows:

[0086] Refer toFigure 1 and Figure 2 , the present invention provides an automatic control system for in-situ direct shear test of rock mass, which includes a normal loading unit 1 for the test piece, a horizontal loading unit 2 for the test piece, a normal data acquisition and pressure control unit 3 for the test piece, a horizontal data acquisition and pressure control unit 4 for the test piece, and a main control terminal 5;

[0087] The normal loading unit 1 for the test piece is arranged between the top surface of the rock mass test piece 6 and the upper mortar 7 directly above it, and is used to apply normal stress to the top surface of the rock mass test piece 6;

[0088] The horizontal loading unit 2 for the test piece is arranged between the side wall of the rock mass test piece 6 and the side mortar 8 on its side, and is used to apply horizontal stress to the side wall of the rock mass test piece 6;

[0089] The normal data acquisition and pressure control unit 3 for the test piece is connected to the normal loading unit 1 for the test piece, and is used to control the normal stress value applied by the normal loading unit 1 for the test piece to the top surface of the rock mass test piece 6, and collect the normal stress value and the normal displacement of the rock mass test piece 6;

[0090] The horizontal data acquisition and pressure control unit 4 for the test piece is connected to the horizontal loading unit 2 for the test piece, and is used to control the horizontal stress value applied by the horizontal loading unit 2 for the test piece to the side wall of the rock mass test piece 6, and collect the horizontal stress value and the horizontal displacement of the rock mass test piece 6;

[0091] The main control terminal 5 is respectively connected to the normal data acquisition and pressure control unit 3 for the test piece and the horizontal data acquisition and pressure control unit 4 for the test piece, and is used to obtain in real time the normal stress value, the horizontal stress value, the normal displacement of the rock mass test piece 6, and the horizontal displacement of the rock mass test piece 6 in the in-situ direct shear test of the rock mass, and control the pressure control units in the normal data acquisition and pressure control unit 3 for the test piece and the horizontal data acquisition and pressure control unit 4 for the test piece.

[0092] As a preferred mode, the normal loading unit 1 for the test piece includes a roller row 1-1, a first steel backing plate 1-2, a first hydraulic jack 1-3, and a force transfer column 1-4;

[0093] Between the top surface of the rock mass specimen 6 and the upper mortar 7 directly above it, in the direction from bottom to top, a row of rollers 1-1, a first steel backing plate 1-2, a first hydraulic jack 1-3, and a load transfer column 1-4 are arranged in sequence. The bottom of the load transfer column 1-4 is clamped and connected to the top surface of the first hydraulic jack 1-3, and the top of the load transfer column 1-4 is in close contact with the upper mortar 7. As a preferred method, the top surface of the rock mass specimen 6, the row of rollers 1-1, the first steel backing plate 1-2, the first hydraulic jack 1-3, and the load transfer column 1-4 are arranged coaxially; and, the cross-sections of the row of rollers 1-1 and the first steel backing plate 1-2 are the same, smaller than the top surface of the rock mass specimen 6, and larger than the cross-section of the first hydraulic jack 1-3. With this structure, the normal stress of the first hydraulic jack 1-3 can be more effectively transmitted to the top surface of the rock mass specimen 6.

[0094] As a preferred method, the specimen normal data acquisition and pressure control unit 3 includes a first electric oil pump 3-1, a first oil pressure sensor 3-2, a first DC battery pack 3-3, the inlet and return oil pipes 3-4 of the first electric oil pump, the inlet and return oil nozzles 3-5 of the first electric oil pump, and a normal displacement acquisition device 3-6;

[0095] The inlet and return oil pipes 3-4 of the first electric oil pump 3-1 are connected to the inlet and return oil nozzles 3-5 of the first electric oil pump of the first hydraulic jack 1-3, and are used to control the normal stress value applied by the first hydraulic jack 1-3;

[0096] The first oil pressure sensor 3-2 is used to collect the normal stress value in real time; the first DC battery pack 3-3 is used to supply power to the first electric oil pump 3-1; the normal displacement acquisition device 3-6 is used to collect the normal displacement of the rock mass specimen 6 in real time.

[0097] As a preferred method, the specimen horizontal loading unit 2 includes a second steel backing plate 2-1, a thrust steel backing plate 2-2, and a second hydraulic jack 2-3; <s

[0098] The second hydraulic jack 2-3 is arranged horizontally, and its axis and the bottom surface of the rock mass specimen 6 are on the same horizontal plane; the base of the second hydraulic jack 2-3 abuts against the side mortar 8, and a thrust steel backing plate 2-2 and a second steel backing plate 2-1 are arranged in sequence between the output end of the second hydraulic jack 2-3 and the side wall of the rock mass specimen 6. <s <s

[0099] As a preferred method, the second steel backing plate 2-1 is attached to the side wall of the rock mass specimen 6 and has the same height as the side wall of the rock mass specimen 6, completely covering the side wall of the rock mass specimen 6; <s <s

[0100] The height of the thrust steel backing plate 2-2 is lower than the height of the second steel backing plate 2-1, and the bottom surface of the thrust steel backing plate 2-2 and the bottom surface of the rock mass specimen 6 are on the same horizontal plane; <s <s

[0101] Therefore, the output end of the second hydraulic jack 2-3, the thrust steel backing plate 2-2, and the second steel backing plate 2-1 are in a stepped form with gradually increasing top surface heights. With this structure, the horizontal stress of the second hydraulic jack 2-3 can be more effectively transmitted to the side wall of the rock mass specimen 6.

[0102] As a preferred embodiment, the specimen horizontal data acquisition and pressure control unit 4 includes a second electric oil pump 4-1, a second oil pressure sensor 4-2, a second DC battery pack 4-3, the inlet and return oil pipes 4-4 of the second electric oil pump, the inlet and return oil nozzles 4-5 of the second electric oil pump, and a horizontal displacement acquisition device 4-6;

[0103] The inlet and return oil pipes 4-4 of the second electric oil pump 4-1 of the second electric oil pump are connected to the inlet and return oil nozzles 4-5 of the second electric oil pump of the second hydraulic jack 2-3, for controlling the horizontal stress value applied by the second hydraulic jack 2-3;

[0104] The second oil pressure sensor 4-2 is used for real-time acquisition of the horizontal stress value; the second DC battery pack 4-3 is used for supplying power to the second electric oil pump 4-1; the horizontal displacement acquisition device 4-6 is used for real-time acquisition of the horizontal displacement of the rock mass specimen 6.

[0105] An automatic control system for in-situ direct shear test of rock mass provided by the present invention, the key equipment includes a main control terminal 5, electronic dial gauges, oil pressure sensors, electric oil pumps, etc., among which:

[0106] The main control terminal 5 should be shockproof, anti-drop, and anti-fall, with a protection level of IP65, a battery life of not less than 24 hours under normal working conditions, a screen size of not less than 7 inches, an internal storage of ≥3G + 32G, and carry WIFI and 4G modules;

[0107] The electronic dial gauge has a range of 0 to 50 mm, a graduation value of 0.01 mm, an accuracy of ≤0.1% F.S, a return error of ±0.01 mm, a protection level of IP67, a continuous battery life of >24 hours in the working state, has wireless transmission and automatic connection after disconnection functions, and its battery power should be displayed by an icon or percentage. During the test, when the battery power is insufficient, there must be an audible or visual prompt for insufficient battery power, and the performance of the dial gauge should be stable and reliable; in the present invention, as Figure 2 shown, a total of four normal-direction electronic dial gauges and four horizontal electronic dial gauges are set, namely: the first normal-direction electronic dial gauge A1; the second normal-direction electronic dial gauge A2; the third normal-direction electronic dial gauge A3; the fourth normal-direction electronic dial gauge A4; the first horizontal electronic dial gauge B1; the second horizontal electronic dial gauge B2; the third horizontal electronic dial gauge B3; the fourth horizontal electronic dial gauge B4.

[0108] Oil pressure sensor, shock-resistant, measuring range 0-60MPa, oil pressure sensor accuracy 0.2, graduation value should not be greater than 0.1MPa, protection grade IP65;

[0109] The electric oil pump should be DC driven, with a rated output pressure of 0 to 60 MPa and a rated flow rate of 0.1 to 1 L / min. The pressurization process should be carried out at a uniform speed, and the pressurization rate should not be too fast. "Pressure inertia" is not allowed, that is, the pressure surges due to the excessively fast pressurization rate, exceeding the set value.

[0110] See Figure 3 The present invention also provides a method for an automatic control system for an in-situ direct shear test of a rock mass, comprising the following steps:

[0111] Step S1, equipment installation and measurement system status confirmation;

[0112] Test equipment according to Figure 1 Install according to Figure 2 Schematic diagram, eight electronic dial indicators are installed in corresponding positions, four of which measure the displacement in the normal (vertical) direction and the horizontal shear direction respectively. After assembly and debugging, when applying shear stress, the normal stress applied to the specimen should be kept unchanged. The main control terminal 5 controls the normal stress to a constant value by real-time pressure increase and pressure reduction through the first oil pressure sensor 3-2, each normal electronic dial indicator and the first electric oil pump 3-1; and the main control terminal 5 simultaneously controls the application of horizontal shear stress through the second oil pressure sensor 4-2, each horizontal electronic dial indicator and the second electric oil pump 4-1. That is, the main control terminal 5 can simultaneously communicate with the specimen normal data acquisition and pressure control unit 3 and the specimen horizontal data acquisition and pressure control unit 4 to conduct in-situ direct shear test of rock mass.

[0113] Step S2, pre-test preparation: select the test type, including rock mass in-situ direct shear test and rock mass in-situ direct shear test friction test;

[0114] Step S3, input key parameters:

[0115] Specifically, after debugging the equipment, according to Figure 3 The execution block diagram of the automatic control process starts the test; first enter the project name, flat tunnel, pilot number and other information, then enter the equipment related parameters, including the oil pressure sensor number, rolling friction resistance, jack output coefficient, etc., and then enter the key test parameters including the shear area of the specimen and the applied directional stress.

[0116] Specifically, the key parameters include: the constant normal stress value σ applied to the specimen in this test yu , specimen shear area, shear angle normal and shear direction jack output coefficient; using formula (1), the program automatically calculates and estimates the estimated value of the horizontal shear stress peak τmax :

[0117] τ max = kσ yu (1)

[0118] Where: k is the estimated coefficient, which is determined according to the test type; if it is an in-situ direct shear test of rock mass, k generally takes 1.5; if it is a friction test of in-situ direct shear test of rock mass, k generally takes 1;

[0119] Therefore, in the present invention, through formula (1), the estimated value of the peak horizontal shear stress is quantified.

[0120] Step S4, confirm key parameters and start the test;

[0121] Step S5, control the normal loading unit 1 of the specimen according to the set key parameters, so as to apply a constant normal stress to the top surface of the rock mass specimen 6, and the value of the normal stress is σ yu ;

[0122] Specifically, when applying the horizontal shear stress in the subsequent steps, the normal stress applied to the specimen should be kept unchanged and be a constant value. Specifically, the main control terminal 5 controls the normal stress to be a constant value through the first oil pressure sensor 3-2, each normal electronic dial gauge and the first electric oil pump 3-1 in real time; and the main control terminal 5 simultaneously controls the application of the horizontal shear stress through the second oil pressure sensor 4-2, each horizontal electronic dial gauge and the second electric oil pump 4-1, that is, the main control terminal 5 can communicate with the specimen normal data acquisition and pressure control unit 3 and the specimen horizontal data acquisition and pressure control unit 4 at the same time to conduct an in-situ direct shear test of rock mass.

[0123] Step S6, judge the stability of the normal stress. When the normal stress is stable, execute Step S7;

[0124] Step S7, control the horizontal loading unit 2 of the specimen, so as to apply a horizontal shear stress to the side wall of the rock mass specimen 6. The specific control method for applying the horizontal shear stress is:

[0125] Step S7.1, adopt formula (2), and apply the horizontal shear stress step by step at a level difference of 1 / 10 of the estimated value τ max of the peak horizontal shear stress and judge the stability. At the same time, the horizontal shear stress and the shear displacement are collected in real time, and the horizontal shear stress-shear displacement curve is generated in real time;

[0126]

[0127] Where: τ n is the nth-level horizontal shear stress; τ n-1is the horizontal shear stress at the (n - 1)th level; n is the level number, increasing from 1. When n = 1, τ n-1 = τ0 = 0; Δτ n is the difference in horizontal shear stress between the nth level and the (n - 1)th level;

[0128] Step S7.2, during the process of gradually applying horizontal shear stress in the manner of Step S7.1, continuously determine whether the increment of shear displacement at the current level reaches 1.5 times the increment of shear displacement at the previous level, that is, determine whether formula (3) holds:

[0129] Δs n = 1.5Δs n-1 (3)

[0130] Where:

[0131] Δs n is the increment of shear displacement at the nth level, that is, the increment of shear displacement at the current level; Δs n-1 is the increment of shear displacement at the (n - 1)th level, that is, the increment of shear displacement at the previous level;

[0132] If formula (3) does not hold, then continue to execute Step S7.1; if formula (3) holds, then execute Step S7.3;

[0133] Step S7.3, starting from applying horizontal shear stress at the (n + 1)th level, halve the level difference, that is, in the manner of formula (4), obtain a new level difference, and then gradually apply horizontal shear stress with the new level difference and judge stability;

[0134]

[0135] Where: τ n+1 is the horizontal shear stress at the (n + 1)th level; Δτ n+1 is the difference in horizontal shear stress between the (n + 1)th level and the nth level, which is the new level difference;

[0136] Step S7.4, during the process of gradually applying horizontal shear stress with the new level difference, if before reaching the horizontal shear peak stress determined in Step S8, the increment of shear displacement at the current level increases to 1.5 times the increment of shear displacement at the previous level again, then the increment of horizontal shear stress applied at the next level is halved compared to the increment of horizontal shear stress applied at the current level until the increment of horizontal shear stress is less than 0.1 Mpa, and execute Step S7.5;

[0137] The formula is:

[0138] When Δs n+m = 1.5Δs n+m-1 then

[0139] Where:

[0140] Δs n+m is the shear displacement increment at the (n + m)-th level;

[0141] Δs n+m-1 is the shear displacement increment at the (n + m - 1)-th level;

[0142] Δτ n+m+1 is the horizontal shear stress increment at the (n + m + 1)-th level;

[0143] Δτ n+m is the horizontal shear stress increment at the (n + m)-th level;

[0144] τ n+m+1 is the horizontal shear stress at the (n + m + 1)-th level;

[0145] τ n+m is the horizontal shear stress at the (n + m)-th level;

[0146] Step S7.5, assume that the horizontal shear stress increment Δτ n+x at the (n + x)-th level < 0.1 Mpa, then the horizontal shear stress increment Δτ n+x+1 at the (n + x + 1)-th level = 0.1 Mpa. Therefore, the horizontal shear stress τ n+x+1 at the (n + x + 1)-th level = τ n+x + 0.1 MPa, where τ n+x is the horizontal shear stress at the (n + x)-th level; then apply the horizontal shear stress step by step with a step difference of 0.1 Mpa, that is, the new step difference is 0.1 Mpa at this time, until the horizontal shear peak stress determined in Step S8 appears;

[0147] This Step S7 is the encryption discrimination criterion before the horizontal shear stress reaches the horizontal shear peak strength, and can be generally described as:

[0148] (1) When applying the horizontal shear stress, apply the horizontal shear stress step by step and judge stability with a step difference of 1 / 10 of the predicted value τ max of the horizontal shear stress peak;

[0149] The formula is:

[0150]

[0151] (2) When the shear displacement increment at this level is 1.5 times that of the previous level, halve the step difference of the applied horizontal shear stress;

[0152] The formula is: when Δs n = 1.5Δs n-1 then τ n+1 = τ n + Δτ n+1 ; τ n+2 = τ n+1 + Δτ n+2 ; …;

[0153] (3) Before reaching the horizontal shear peak, when the shear displacement increment at a certain level increases to 1.5 times the shear displacement increment at the previous level again, the horizontal shear stress increment applied at the next level is halved compared to the horizontal shear stress increment at the current level until the horizontal shear stress increment is less than 0.1 MPa or reaches the horizontal shear peak;

[0154] The formula is:

[0155] When the shear displacement increment Δs at the n + m level n+m = 1.5Δs n+m-1 then the horizontal shear stress increment at the n + m + 1 level The horizontal shear stress τ at the n + m + 1 level n+m+1 = τ n+m + Δτ n+m+1 ;

[0156] When the horizontal shear stress increment Δτ at the n + x level n+x < 0.1 Mpa, then the horizontal shear stress increment Δτ at the n + x + 1 level n+x+1 = 0.1 Mpa, and the horizontal shear stress τ at the n + x + 1 level n+x+1 = τ n+x + 0.1 MPa.

[0157] Step S8, during the process of applying the horizontal shear stress in the manner of step S7, the determination criterion for the horizontal shear peak stress is:

[0158] (1) As Figure 4 shown, if the specimen belongs to the rock mass type that undergoes brittle shear failure: the horizontal shear stress at the current level is lower than the horizontal shear stress at the previous level, the horizontal shear stress at the previous level is higher than the horizontal shear stress at the level above the previous level, and the value by which the horizontal shear stress at the current level decreases is 2 times or more the value by which the horizontal shear stress at the previous level increases, then the horizontal shear stress at the previous level is determined as the horizontal shear peak stress;

[0159] The formula is:

[0160] When Δτ s < 0, Δτ s-1 > 0, and |Δτ s | ≥ 2|Δτ s-1 |, then τ' max = τ s-1 ;

[0161] Where: Δτ s represents the difference between the horizontal shear stress at the current level and the horizontal shear stress at the previous level;

[0162] Δτ s-1 represents the difference between the upper-level horizontal shear stress and the upper-upper-level horizontal shear stress;

[0163] τ s-1 represents the upper-level horizontal shear stress;

[0164] τ′ mas represents the peak horizontal shear stress;

[0165] (2) As Figure 5 shown, if the test piece belongs to the rock mass type that undergoes plastic shear failure: within a certain time period, preferably 60 s, the horizontal shear stress fluctuates within a certain range, and the fluctuation range is ±0.05 MPa, then the average value of the horizontal shear stress within this time period is determined as the peak horizontal shear stress;

[0166] The formula is:

[0167] When T n ≥T n-s +60, τ da =max{τ n-s , τ n-s+1 , τ n-s+2 ,..., τ n-1 , τ n , τ xiao =min{τ n-s , τ n-S+1 , τ n-s+2 ,..., τ n-1 , τ n , τ da -τ xiao ≤0.1 MPa, then τ′ max =average{τ n-s , τ n-s+1 , τ n-s+2 ,..., τ n-1 , τ n};

[0168] Among them:

[0169] For the time periods of the n-s level, the n-s+1 level,..., the n level, T n represents the time of the n level, T n-s represents the time of the n-s level, and this time period is greater than or equal to 60 s; τ n-s , τ n-s+1 , τ n-s+2 ,..., τ n-1 , τ n represent the horizontal shear stresses corresponding to each time period;

[0170] (3) If the specimen for the direct shear test does not belong to the rock mass types that undergo brittle shear failure and plastic shear failure, that is, when it is not one of the above two types: then when the total horizontal shear displacement reaches 15 mm, the average value of the shear data at a total of 5 levels before and after the maximum horizontal shear stress within 15 mm is taken as the horizontal shear peak stress;

[0171] The formula is:

[0172] When the cumulative horizontal shear displacement S from the 1st level to the kth level k ≥15 mm, τ z =max{τ1,τ2,τ3,...,τ k-1 ,τ k}, then τ′ max =average{τ z-2 ,τ z-1 ,τ z ,τ z+1 ,τ z+2}, and 2 < z ≤ k.

[0173] Where: τ z represents the maximum horizontal shear stress from the 1st level to the kth level; therefore, the maximum horizontal shear stress is the horizontal shear stress at the zth level.

[0174] Step S9, after obtaining the horizontal shear peak stress through Step S8, during the subsequent test when applying the horizontal shear stress, it is controlled by shear displacement, and the horizontal shear stress - shear displacement data is recorded every time the shear displacement increases by 0.50 mm until the total shear displacement exceeds 35 mm, and the test ends.

[0175] The formula is expressed as: when τ′ max is obtained, s l+1 =s l +0.5 mm; when the cumulative horizontal shear displacement S p ≥35 mm, the test ends.

[0176] The present invention provides an automatic control method for in - situ direct shear test of rock mass, Figure 3 and the execution block diagram of the automatic control process for the in - situ direct shear test of rock mass is given in

[0177] Step S1, equipment installation and confirmation of the state of the measurement system;

[0178] Step S2, preparation before the test: select the test type; input the project name, adit, pilot hole number and stake number, input the pressure sensor number, and the rolling row frictional resistance;

[0179] Step S3, Input of key parameters: Input the shear area of the specimen, the normal of the shear angle, the jack output coefficient in the shear direction, and the normal stress value, and automatically calculate the estimated peak value of the horizontal shear stress.

[0180] Step S4, Parameter confirmation and start of the test; if parameters need to be modified, return to Step S3.

[0181] Step S5, Application of normal load: Apply in 3 levels according to the set parameters, and execute the process according to the specifications.

[0182] Step S6, Stability judgment of normal stress; if it is not stable, return to Step S4, pop up the manual adjustment interface, and modify the normal stress value.

[0183] Step S7, Application of horizontal shear stress: After the normal stress loading is completed, pop up the options of pause / confirmation / parameter modification for the horizontal shear stress application interface. If the tester does not operate for 15s on the estimated maximum applied horizontal shear peak stress, directly enter the horizontal shear stress loading link.

[0184] Step S8, Apply the horizontal shear stress step by step with a step difference of 1 / 10 of the estimated maximum horizontal shear stress value and judge stability, collect stress and displacement data; generate a data record table of stress-displacement curve in real time and view the monitoring by swiping the screen.

[0185] Step S9, When the horizontal shear displacement increment is 1.5 times that of the previous level, halve the step difference of the horizontal shear stress.

[0186] Step S10, Apply the horizontal shear stress with the new step difference (the new step difference should be > 0.1 MPa, otherwise use 0.1 MPa as the step difference).

[0187] Step S11, When one of the following three conditions is met, obtain the peak value of the horizontal shear stress:

[0188] If the horizontal shear stress of this level is lower than that of the previous level, the stress of the previous level is higher than that of the level above the previous level, and the decreased value of the stress of this level is 2 times or more of the increased value of the stress of the previous level, then determine the stress of the previous level as the peak value of the horizontal shear stress;

[0189] Within any 60s interval, the horizontal shear stress fluctuates within a certain range, and the fluctuation range is ±0.05 MPa, then determine the average value of the shear stress within the measured time period as the peak strength stress;

[0190] When the total horizontal shear displacement reaches 15 mm, take the maximum horizontal shear stress within 15 mm and the average value of a total of 5 groups of shear data before and after as the horizontal shear peak value.

[0191] In step S12, after obtaining the horizontal shear peak stress, the subsequent test applies the horizontal shear stress under displacement control, records the stress-displacement data every time the displacement increases by 0.50 mm until the total displacement exceeds 35 mm;

[0192] In step S13, post-test description: Take photos of the upper and lower plates of the shear plane. The photos are named according to the test points and can be edited. The post-test description is divided into the upper and lower plates;

[0193] In step S14, the single-point test ends.

[0194] Different from the traditional in-situ direct shear test method for rock masses, it is necessary for the test personnel to apply and unload the vertical and horizontal stresses, record the displacement and stress data, and for the test personnel to judge the horizontal shear peak strength and control the test process. The beneficial effect of the present invention is that by using test equipment such as a main control terminal machine, an electronic dial gauge, an oil pressure sensor, and an electric oil pump, according to the clear peak strength prediction standard formula, the encryption discrimination standard before the horizontal shear stress reaches the peak strength, the actual peak strength quantization discrimination formula and boundary conditions of the horizontal stress during the test process, and in accordance with the specific execution steps of the automatic program, the automatic control process of the in-situ direct shear test for rock masses is realized, eliminating the cumbersome labor of personnel and improving the test efficiency and the degree of test automation.

[0195] In addition, it should be understood that although this specification is described according to the embodiments, not every embodiment only contains an independent technical solution. This narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for using an automatic control system for in-situ direct shear testing of rock mass, characterized in that: The following steps are involved: Step S1, equipment installation and measurement system status confirmation; Step S2, pre-test preparation: select the test type, including rock mass in-situ direct shear test and rock mass in-situ direct shear test friction test; Step S3, input key parameters: In this test, the constant normal stress value σ applied to the specimen yu , shear area of the specimen, shear angle normal and shear direction jack output coefficient; Using formula (1), we can get the estimated value of the peak horizontal shear stress τ max : t max =kσ yu (1) Where: k is the estimated coefficient, which is determined according to the test type; if it is an in-situ direct shear test of rock mass, k is 1.5; if it is an in-situ direct shear test of rock mass friction test, k is 1; Step S4, confirm key parameters and start the test; Step S5, according to the set key parameters, the specimen normal loading unit (1) is controlled to apply a constant normal stress to the top surface of the rock specimen (6), and the normal stress value is σ yu ; Step S6, judging whether the normal stress is stable. When the normal stress is stable, executing step S7; Step S7, controlling the specimen horizontal loading unit (2) to apply horizontal shear stress to the side wall of the rock specimen (6). The specific control method for applying the horizontal shear stress is: Step S7.1, using formula (2), according to the estimated value of the horizontal shear stress peak τ max The horizontal shear stress is applied step by step and the stability is judged. At the same time, the horizontal shear stress and shear displacement are collected in real time, and the horizontal shear stress-shear displacement curve is generated in real time. Where: τ n is the nth level shear stress; τ n-1 is the n-1th level shear stress; n is the number of levels, starting from 1 and increasing. When n=1, τ n-1 =τ0=0;Δτ n is the difference between the nth and n-1th level horizontal shear stresses; Step S7.2: During the stepwise application of horizontal shear stress in the manner of step S7.1, it is determined in real time whether the shear displacement increment of the current stage reaches 1.5 times the shear displacement increment of the previous stage, that is, whether formula (3) is established: Δs n =1.5Δs n-1 (3) in: Δs n is the nth level shear displacement increment, that is, the current level shear displacement increment; Δs n-11 is the n-1th stage shear displacement increment, that is, the previous stage shear displacement increment; If formula (3) is not true, continue to step S7.1; if formula (3) is true, go to step S7.3; Step S7.3, starting from applying horizontal shear stress at level n+1, the level difference is halved, that is, a new level difference is obtained according to formula (4), and then horizontal shear stress is applied step by step with the new level difference and stability is determined; Where: τ +11 is the n+1th level shear stress; Δτ +11 is the difference between the horizontal shear stress of level n+1 and level n, and is the new difference; Step S7.4: During the process of applying horizontal shear stress step by step with the new step difference, if the shear displacement increment of the current stage increases again to 1.5 times the shear displacement increment of the previous stage before reaching the horizontal shear peak stress determined in step S8, the horizontal shear stress increment applied at the next stage is further reduced by half compared to the horizontal shear stress increment applied at the current stage until the horizontal shear stress increment is less than 0.1 MPa, and then step S7.5 is executed. The formula is: When Δs n+m = 1.5Δs n+m-1 then τ n+m+1 = τ n+m + Δτ n+m+1 ; in: Δs n+m is the shear displacement increment of the n+mth level; Δs n+m-1 is the shear displacement increment of the n+m-1th level; Δτ n+m+1 is the horizontal shear stress increment of level n+m+1; Δτ n+m is the horizontal shear stress increment of level n+m; τ n+m+1 is the horizontal shear stress at level n+m+1; τ n+m is the horizontal shear stress at level n+m; Step S7.5, assume that the n+xth level shear stress increment Δτ n+x <0.1Mpa, then the n+x+1 level horizontal shear stress increment Δτ n+x+1 =0.1Mpa, therefore, the n+x+1th level shear stress τ n+x+1 =τ n+x +0.1MPa, where τ n+x is the n+xth level horizontal shear stress; then, with a step difference of 0.1 MPa, that is, the new step difference is 0.1 MPa, the horizontal shear stress is applied step by step with the new step difference until the horizontal shear peak stress determined in step S8 appears; Step S8: During the process of applying horizontal shear stress in the manner of step S7, the horizontal shear peak stress determination standard is: (1) If the specimen belongs to the type of rock mass that undergoes brittle shear failure: the horizontal shear stress of this level is lower than the horizontal shear stress of the upper level, the horizontal shear stress of the upper level is higher than the horizontal shear stress of the upper level, and the value of the decrease in the horizontal shear stress of this level is 2 times or more of the value of the increase in the horizontal shear stress of the upper level, then the upper level horizontal shear stress is determined to be the horizontal shear peak stress; (2) If the specimen belongs to the type of rock mass that undergoes plastic shear failure: within any 60-s interval, the horizontal shear stress fluctuates within a certain range, with the fluctuation range being ±0.05 MPa. The average value of the horizontal shear stress within this period is determined as the horizontal shear peak stress; (3) If the specimen undergoing direct shear test does not belong to the rock mass type that undergoes brittle shear failure or the rock mass type that undergoes plastic shear failure, when the total horizontal shear displacement reaches 15 mm, the average value of the five levels of shear data before and after the maximum horizontal shear stress within 15 mm is taken as the horizontal shear peak stress; Step S9: After obtaining the horizontal shear peak stress through step S8, the horizontal shear stress is applied in subsequent tests with shear displacement control. The horizontal shear stress and shear displacement data are recorded every time the shear displacement increases by 0.50 mm until the total shear displacement exceeds 35 mm, and the test is terminated.

2. An automatic control system for in-situ direct shear test of rock mass, characterized in that: The rock mass in-situ direct shear test automatic control system is a system adopted by the method of adopting the rock mass in-situ direct shear test automatic control system as claimed in claim 1, comprising a specimen normal loading unit (1), a specimen horizontal loading unit (2), a specimen normal data acquisition and pressure control unit (3), a specimen horizontal data acquisition and pressure control unit (4) and a main control terminal (5); The specimen normal loading unit (1) is arranged between the top surface of the rock specimen (6) and the upper mortar (7) directly above it, and is used to apply normal stress to the top surface of the rock specimen (6); The specimen horizontal loading unit (2) is arranged between the side wall of the rock specimen (6) and the side mortar (8) on the side thereof, and is used to apply horizontal stress to the side wall of the rock specimen (6); The specimen normal data acquisition and pressure control unit (3) is connected to the specimen normal loading unit (1) and is used to control the specimen normal loading unit (1) to apply a normal stress value to the top surface of the rock specimen (6), and to acquire the normal stress value and the normal displacement of the rock specimen (6); The specimen horizontal data acquisition and pressure control unit (4) is connected to the specimen horizontal loading unit (2) and is used to control the specimen horizontal loading unit (2) to apply a horizontal stress value of a horizontal stress to the side wall of the rock specimen (6), and to collect the horizontal stress value and the horizontal displacement of the rock specimen (6); The main control terminal (5) is connected to the specimen normal data acquisition and pressure control unit (3) and the specimen horizontal data acquisition and pressure control unit (4) respectively, and is used to obtain the normal stress value, the horizontal stress value, the normal displacement of the rock specimen (6) and the horizontal displacement of the rock specimen (6) in real time during the in-situ direct shear test of the rock mass, and to control the pressure control units in the specimen normal data acquisition and pressure control unit (3) and the specimen horizontal data acquisition and pressure control unit (4).

3. The automatic control system for in-situ direct shear testing of rock mass according to claim 2, characterized in that: The specimen normal loading unit (1) comprises a roller row (1-1), a first steel pad (1-2), a first hydraulic jack (1-3) and a force transmission column (1-4); Between the top surface of the rock specimen (6) and the upper mortar (7) directly above it, the roller row (1-1), the first steel pad (1-2), the first hydraulic jack (1-3) and the force transmission column (1-4) are arranged in sequence from bottom to top, and the bottom of the force transmission column (1-4) is snap-connected with the top surface of the first hydraulic jack (1-3), so that the top of the force transmission column (1-4) is in close contact with the upper mortar (7).

4. The automatic control system for in-situ direct shear testing of rock mass according to claim 3, characterized in that: The top surface of the rock specimen (6), the roller row (1-1), the first steel pad (1-2), the first hydraulic jack (1-3) and the force transmission column (1-4) are coaxially arranged; and the cross-sections of the roller row (1-1) and the first steel pad (1-2) are the same, smaller than the top surface of the rock specimen (6) and larger than the cross-section of the first hydraulic jack (1-3).

5. The automatic control system for in-situ direct shear test of rock mass according to claim 3, characterized in that: The specimen normal data acquisition and pressure control unit (3) comprises a first electric oil pump (3-1), a first oil pressure sensor (3-2), a first DC battery pack (3-3), an oil inlet and return pipe (3-4) of the first electric oil pump, an oil inlet and return nozzle (3-5) of the first electric oil pump, and a normal displacement acquisition device (3-6); The oil inlet and return pipes (3-4) of the first electric oil pump (3-1) are connected to the oil inlet and return nozzles (3-5) of the first electric oil pump of the first hydraulic jack (1-3), and are used to control the normal stress value applied by the first hydraulic jack (1-3); The first oil pressure sensor (3-2) is used to collect the normal stress value in real time; The first DC battery pack (3-3) is used to supply power to the first electric oil pump (3-1); The normal displacement acquisition device (3-6) is used to acquire the normal displacement of the rock mass specimen (6) in real time.

6. The automatic control system for in-situ direct shear testing of rock mass according to claim 2, characterized in that: The specimen horizontal loading unit (2) comprises a second steel pad (2-1), a thrust steel pad (2-2) and a second hydraulic jack (2-3); The second hydraulic jack (2-3) is arranged horizontally, and its axis and the bottom surface of the rock specimen (6) are located in the same horizontal plane; the base of the second hydraulic jack (2-3) is against the side mortar (8), and the thrust steel plate (2-2) and the second steel plate (2-1) are arranged in sequence between the output end of the second hydraulic jack (2-3) and the side wall of the rock specimen (6).

7. The automatic control system for in-situ direct shear testing of rock mass according to claim 6, characterized in that: The second steel plate (2-1) is attached to the side wall of the rock mass specimen (6) at the same height as the side wall of the rock mass specimen (6), completely covering the side wall of the rock mass specimen (6); The height of the thrust steel plate (2-2) is lower than the height of the second steel plate (2-1), and the bottom surface of the thrust steel plate (2-2) and the bottom surface of the rock mass specimen (6) are located on the same horizontal plane; Therefore, the output end of the second hydraulic jack (2-3), the thrust steel plate (2-2) and the second steel plate (2-1) are in a stepped form with gradually increasing top surface heights.

8. The automatic control system for in-situ direct shear testing of rock mass according to claim 6, characterized in that: The test piece horizontal data acquisition and pressure control unit (4) comprises a second electric oil pump (4-1), a second oil pressure sensor (4-2), a second DC battery pack (4-3), an oil inlet and return pipe (4-4) of the second electric oil pump, an oil inlet and return nozzle (4-5) of the second electric oil pump, and a horizontal displacement acquisition device (4-6); The oil inlet and return pipes (4-4) of the second electric oil pump (4-1) are connected to the oil inlet and return nozzles (4-5) of the second electric oil pump of the second hydraulic jack (2-3), and are used to control the horizontal stress value applied by the second hydraulic jack (2-3); The second oil pressure sensor (4-2) is used to collect the horizontal stress value in real time; The second DC battery pack (4-3) is used to supply power to the second electric oil pump (4-1); The horizontal displacement acquisition device (4-6) is used to acquire the horizontal displacement of the rock mass specimen (6) in real time.

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