CN112129632B - Method for calibrating creep damage and fracture surface of rock by using high-density resistivity - Google Patents
Method for calibrating creep damage and fracture surface of rock by using high-density resistivity Download PDFInfo
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Abstract
The invention provides a method for calibrating creep damage and fracture surface of a rock by using high-density resistivity, which comprises the following steps: s1: drilling; s2: installing an electrode wire; s3: carrying out vacuum water saturation treatment; s4: surface water sealing treatment; s5: installing a strain gauge; s6: connecting the electrode wire with a high-density resistivity meter; s7: placing on a press; s8: measuring initial resistivity data when the load is not applied; s9: starting the press machine; s10: storing data in real time until the rock test piece is crushed; s11: processing data; s12: and comprehensively calibrating the creep damage and potential fracture surface development conditions of the rock according to the obtained resistivity-time curve, resistivity-strain curve, stress-strain curve, time-strain curve and rock apparent resistivity profile. The invention adopts the high-density resistivity meter to measure the rock test piece, and overcomes the defects of larger error, less measuring points, poor intuition and the like of experimental data of a dipolar method and a quadrupole method.
Description
Technical Field
The invention belongs to the field of rock mechanical engineering, and relates to a method for measuring high-density resistivity of a creep rock in real time, in particular to a method for calibrating creep damage and fracture surface of the rock by using the high-density resistivity.
Background
Water inrush is a common geological disaster in tunnel engineering construction, and generally, tunnel water inrush can be divided into 'instantaneous water inrush' and 'lag water inrush', the instantaneous water inrush refers to a water inrush phenomenon occurring immediately in an excavation unloading process or in a very short time after excavation, the lag water inrush refers to a water inrush phenomenon occurring after a period of time creep after rock excavation, the time span can vary from several hours to even several months, and the occurrence of damage has a time delay effect.
The resistivity is a basic physical quantity of the rock and is closely related to the porosity, density, water content, fracture development condition and the like of the rock. When the rock is loaded, the internal structure evolves and microcracks are initiated, expanded and run through, so that water in the rock is filled in gaps, a conductive path is changed, and resistivity data acquired by the high-density resistivity instrument is changed.
Therefore, the method for calibrating the creep damage and the potential fracture surface of the rock by using the high-density resistivity method is very significant for predicting, early warning and preventing the tunnel from water inrush disasters.
At present, in the field of rock mechanical engineering, the research on real-time resistivity measurement in the whole process of creep failure of rock is less.
The existing resistivity measuring methods mainly comprise a dipolar method and a quadrupole method, and the research for measuring the rock resistivity by using a high-density resistivity meter is almost not available. The two-pole method is to symmetrically arrange electrodes on two end faces of a rock test piece to directly measure the resistivity, but due to the existence of contact resistance, the test data has larger errors. The quadrupole method comprises A, B, M, N four electrodes, wherein A and B are power supply electrodes, M and N are measuring electrodes, and although the quadrupole method is greatly improved on the basis of the two-pole method, the resistivity change of different positions in the creep damage of rocks cannot be truly reflected due to few measuring points.
At present, most of researches on the resistivity of the rock are still in the research on the resistivity change of a single side and a single direction, because the rock is an anisotropic body, the expansion direction of an internal fracture is difficult to determine in the loading process, and apparent resistivity profile diagrams obtained by measuring lines of different measuring surfaces are very different, so that the rock apparent resistivity profile diagrams obtained by only measuring the single side and the single direction cannot accurately calibrate the positions of the creep damage and the potential fracture surface of the rock.
In the research on the apparent resistivity anisotropy characteristics of the rock, only 4 or 8 electrodes are arranged on each measuring line, the resistivity anisotropy of one or two depth layers is only researched, and the research on the resistivity anisotropy with larger depth is lacked, so that the potential fracture surface information in the rock creep process is difficult to obtain.
Most of the electrodes are directly adhered to the surface of the rock sample by using conductive adhesive, and the method has the defects that the electrodes are greatly influenced by manual operation and are easy to fall off, and the lead cannot be fully contacted with the rock.
Disclosure of Invention
According to the technical problem, a method for calibrating the creep damage and fracture surface of the rock by using high-density resistivity is provided.
The technical means adopted by the invention are as follows:
a method for calibrating creep damage and fracture surfaces of rocks by using high-density resistivity comprises the following steps:
s1: respectively drilling a plurality of rows of drill holes on three side surfaces of a cuboid rock test piece by using electric drills;
s2: installing an electrode wire in each drill hole, wherein one end of the electrode wire is connected with the drill hole;
s3: carrying out 24-hour water saturation treatment on the rock test piece with the electrode wire under a vacuum condition;
s4: performing surface water sealing treatment on the rock test piece obtained in the step S3;
s5: performing surface cleaning on the side surface without the drilled hole of the rock test piece obtained in the step S4, and installing a strain gauge in the center of the side surface, wherein the strain gauge is connected with a static strain measuring instrument;
s6: connecting the other ends of all the electrode wires with a high-density resistivity meter;
s7: placing the rock test piece obtained in the step S6 on a press machine, and filling plastic insulation plates between the upper surface and the lower surface of the rock test piece and the contact surfaces of the upper pressing plate and the lower pressing plate of the press machine to achieve an insulation effect;
s8: measuring initial resistivity data when the load is not applied;
s9: starting a press machine to start a test;
s10: storing the data collected by the high-density resistivity instrument and the stress-strain data of the rock test piece in real time until the rock test piece is crushed, and stopping the test;
s11: data processing: transmitting the measurement data stored in the high-density resistivity instrument to a computer, processing the measurement data by the computer, and drawing a resistivity-time curve, a resistivity-strain curve, a stress-strain curve, a time-strain curve and apparent resistivity profile maps of the rock test piece in different directions and different time nodes;
s12: and comprehensively calibrating the creep damage and potential fracture surface development conditions of the rock according to the obtained resistivity-time curve, resistivity-strain curve, stress-strain curve, time-strain curve and rock apparent resistivity profile.
Further, in the step S4, an epoxy resin is used as the water sealing material, and the ratio of the epoxy resin to the curing agent is 3: and 1, then placing the rock test piece subjected to surface water sealing treatment in a dry and ventilated place for 24 hours, and then completely curing, wherein the curing agent is an epoxy curing agent.
In the step S5, the surface of the rock specimen obtained in the step S4, which does not have the drilled hole, is scraped by a scraper to remove the epoxy resin in the center of the surface, and then is polished by coarse and fine sandpaper in sequence, and finally the polished area is cleaned by alcohol, and a strain gauge and a connection terminal are attached, and one end of a lead is connected with the strain gauge through the connection terminal, and the other end of the lead is connected with a static strain gauge.
Further, in the step S2, a graphite conductive adhesive is uniformly coated on the electrode wire, inserted into the drilled hole, and completely cured after being placed in a dry and ventilated place for 24 hours.
Further, in the step S5, the strain gauge is fixed to the rock surface by bonding, and the transverse strain gauge is perpendicular to the height direction of the rock specimen, and the longitudinal strain gauge is parallel to the height direction of the rock specimen.
Further, in the step S1, four rows of drill holes are formed in the side surface of each rock specimen, wherein one row of drill holes is parallel to the height direction of the rock specimen, one row of drill holes is perpendicular to the height direction of the rock specimen, the other two rows of drill holes respectively form an angle of 45 degrees with the height direction of the rock specimen, the hole diameter of each drill hole is 1mm, the depth of each drill hole is 10mm, and the distance between the centers of two adjacent drill holes in each row of drill holes is 5 mm.
The high-density resistivity instrument comprises a host machine and a slave machine, wherein the host machine is a multifunctional direct current electrical method instrument, the slave machine is a multi-way electrode converter, a storage battery is connected with the slave machine, the host machine is connected with the slave machine, and all electrode wires are connected with the slave machine.
In the step S8, the single chip microcomputer controls and converts the arrangement mode, the polar distance and the measuring point positions of the electrodes of the electrode wires in the measuring process, so as to automatically complete the data acquisition work of each measuring point and multiple devices, and store the measuring result in the high-density resistivity meter.
In step S9, a creep mechanical test is performed according to a set stress path, and the start times of the press, the high-density resistivity method instrument, and the static strain gauge are synchronized, so that convenience is provided for later-stage data analysis.
In the step S11, dead spots are removed, and the apparent resistivity profile of the rock is obtained based on a round-robin least square computer inversion calculation procedure.
And analyzing the anisotropic characteristics of the resistivity change of different measuring lines (each row of drill holes) according to the apparent resistivity profile of the rock, and obtaining the position of the potential fracture surface according to the anisotropic coefficient lambda of the apparent resistivity of different depths.
Compared with the prior art, the invention has the following advantages:
1. the high-density resistivity instrument is adopted to measure the rock test piece, and the defects of large error, few measuring points, poor intuition and the like of experimental data of a dipolar method and a quadrupole method are overcome.
2. The real-time acquisition of the resistivity of the rock in the creep process by using a high-density resistivity instrument is realized, and the creep damage and potential fracture surface development conditions of the rock can be comprehensively calibrated by using changes of a rock apparent resistivity profile, a resistivity-strain curve, a strain-stress curve and a time-strain curve obtained by a tomography technology.
3. The anisotropy characteristics of the apparent resistivity of the rock are researched, and the defects that the damage and the fracture surface development of the rock are analyzed only through the single-side unidirectional resistivity change are overcome.
4. In the research on the anisotropic characteristics of the apparent resistivity of the rock, more measuring points (drill holes) are arranged on each measuring line (each row of drill holes), so that the anisotropic resistivity of the rock with larger depth is analyzed, and a theoretical basis is provided for searching a potential fracture surface.
5. Through drilling on the surface of the rock test piece and arranging the electrodes, the electrode wire is fully contacted with the rock test piece as far as possible on the premise of not changing the mechanical property of the rock, and the test error is reduced.
Based on the reason, the method can be widely popularized in the fields of monitoring and early warning of the creep rock destruction process and the like.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
FIG. 1 is a flow chart of a method for calibrating rock creep damage and fracture surfaces by using high density resistivity according to an embodiment of the invention.
FIG. 2 is a schematic illustration of a rock sample placed on a press in an embodiment of the present invention.
FIG. 3 is a schematic diagram of a symmetric quadrupole device in accordance with an embodiment of the present invention.
FIG. 4 is a schematic illustration of a rock sample in an embodiment of the invention.
Fig. 5 is a right side view of fig. 4.
FIG. 6 is a data pair and probe depth map in accordance with an embodiment of the present invention.
FIG. 7 is a schematic diagram of the connection of a rock sample to a high density resistivity tool in accordance with an embodiment of the present invention.
FIG. 8 is an apparent resistivity profile of a borehole 41A as measured by a formation survey line in accordance with an embodiment of the present invention.
FIG. 9 is a graph of strain-time, resistivity-time at the point A of single stage loading creep in an embodiment of the present invention.
FIG. 10 is a stress-strain, resistivity-strain plot for single stage loaded creep at the A point in accordance with an embodiment of the present invention.
FIG. 11 is a stress-strain, resistivity-strain diagram of graded loaded creep A-point in an embodiment of the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. Any specific values in all examples shown and discussed herein are to be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.
In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the orientation or positional relationship shown in the drawings, and are used for convenience of description and simplicity of description only, and in the absence of any contrary indication, these directional terms are not intended to indicate and imply that the device or element so referred to must have a particular orientation or be constructed and operated in a particular orientation, and therefore should not be considered as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.
Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.
It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.
As shown in fig. 1 to 11, a method for calibrating rock creep damage and fracture surface by using high density resistivity, in which a high density resistivity meter 1, a TST3822EW static strain gauge, a 3000KN press 2, a 12V storage battery 3, an electric drill and a green sand rock test piece (hereinafter referred to as rock test piece) 4 are used, the rock test piece 4 is a cuboid, the high density resistivity meter 1 comprises a master (DZD-6A multifunctional direct current method meter) 11 and a slave (MIS-120 multi-way electrode converter) 12, and comprises the following steps:
s1: drilling 4 rows of drill holes on each of the three side surfaces of the rock specimen 4 with an electric drill: four rows of boreholes on one of the sides are boreholes 41(A, B, C, D), four rows of boreholes on one of the sides are boreholes 42(A, B, C, D), and four rows of boreholes on the remaining side are micro-boreholes 43(A, B, C, D);
s2: installing an electrode wire 46 in each borehole, one end of the electrode wire 46 being connected to the borehole;
s3: carrying out 24-hour water saturation treatment on the rock test piece 4 obtained in the step S2 under a vacuum condition;
s4: the rock test piece 4 obtained through step S3 is subjected to surface water sealing treatment. Epoxy resin is adopted as a water sealing material and matched with a curing agent, and the matching proportion is 3: 1, placing the mixture in a dry and ventilated place for 24 hours until the mixture is completely cured;
s5: scraping off epoxy resin in the middle of the side surface where the electrode wire is not arranged by using a scraper for the rock test piece 4 obtained in the step S4, sequentially polishing the side surface with coarse and fine abrasive paper, cleaning a polishing area with alcohol, adhering a strain gauge 44 (a strain gauge is transversely arranged and a strain gauge is vertically arranged) and a wiring terminal, connecting one end of a lead with the strain gauge through the wiring terminal, and connecting the other end of the lead with a TST3822EW static strain gauge;
s6: all electrode wires 46 are connected with the high-density resistivity meter 1, and a 12V storage battery 3 is used for supplying power to the slave 12;
s7: placing the rock test piece 4 on a press machine 2, and respectively padding plastic insulation plates 45 between the upper surface and the lower surface of the rock test piece 4 and the contact surfaces of an upper pressing plate 21 and a lower pressing plate 22 of the press machine 2;
s8: measuring initial resistivity data when the load is not applied;
s9: starting the press 2 to start the test;
s10: storing data collected by the high-density resistivity instrument 11 in real time; the press machine 2 records the stress sigma of the rock test piece 4 in real time; and recording the strain value displayed by the static strain measuring instrument in real time until the rock test piece 4 is crushed, and stopping the test. The personal safety of the testers is protected by the protective cover 23 in the test process;
s11: data processing: transmitting the measurement data stored in the high-density resistivity instrument 11 to a computer, processing the data by the computer through software to obtain apparent resistivity profile maps of different orientations and different time nodes of the rock test piece, and drawing a resistivity-time curve, a resistivity-strain curve, a stress-strain curve and a time-strain curve according to the collected stress-strain data;
s12: and comprehensively calibrating the creep damage and potential fracture surface development conditions of the rock according to the apparent resistivity profile, the resistivity-time curve, the resistivity-strain curve, the stress-strain curve and the time-strain curve of the rock.
In step S1, the rock specimen 4 is a green sand specimen of 100mm × 100mm × 200mm, and the four rows of holes on the side surface of each rock specimen (A, B, C, D) include a line a (row a holes) parallel to the axial force (rock height direction), a line B, C at an angle of 45 ° to the axial force, a line D perpendicular to the axial force (see fig. 5), a hole diameter of 1mm, a depth of 10mm, and an equal distance between holes, and L is 5 mm.
In step S2, graphite conductive paste is uniformly applied on the electrode wire 46, inserted into the drilled hole, and placed in a dry and ventilated place for 24h until it is completely cured.
In step S5, the strain gauge 44 is firmly adhered to the surface of the rock sample 4, and the transverse strain gauge is ensured to be perpendicular to the height direction of the rock sample 4, and the longitudinal strain gauge is ensured to be parallel to the height direction of the rock sample 4, and after completion, the strain gauge 44 is ensured to be usable by ohmmeter detection.
In step S6, the 12V battery 3 is connected to the slave 12, the master 11 is connected to the slave 12, and the electrode line 46 is connected to the slave 12.
In the step S8, the single chip microcomputer controls the arrangement mode, the pole pitch, and the measuring point positions of the electrodes of the electrode wires in the measuring process, so as to automatically complete the data acquisition of each measuring point and multiple devices, and store the result in the multifunctional direct current meter 11.
In the step S9, single-stage loading and step-loading creep tests are performed according to a set stress path, and the start time of the press 2, the high-density resistivity method instrument 1 and the static strain gauge is synchronized, so that convenience is provided for later-stage data analysis.
In the step S11, dead spots are removed, and the apparent resistivity profile of the rock is obtained based on a round-robin least square computer inversion calculation procedure. The round-robin constrained least squares method is based on the following equation:
(j'j+uF)d＝j'g
F＝fxf'x+fzf'z
in the formula:
f is an objective function;
fxis a horizontal smoothing filter coefficient matrix;
fzis a vertical smoothing filter coefficient matrix;
f'xis fxThe transposed matrix of (2);
f'zis fzThe transposed matrix of (2);
j is a partial derivative matrix;
j' is the transposed matrix of j;
u is a damping coefficient;
d is a model parameter modification vector;
g is a residual vector.
Analysis according to the attached figures:
the high-density resistivity instrument 1 measures an apparent resistivity profile (fig. 8) of the rock test piece 4 in a single-stage loading creep test process through the electrode wire 46 arranged in the drill hole 41A, wherein the lightest color represents a low-resistance area, the deepest color represents a high-resistance area, and the middle color is a low-resistance to high-resistance transition area. With the increase of strain, the cracks in the rock gradually develop, the micro cracks are communicated, so that the internal water is gradually filled in the cracks to reduce the apparent resistivity, and at the moment, the development of the low-resistance area can be analyzed to judge the creep damage stage of the rock. And comprehensively calibrating the creep damage and the potential fracture surface position of the rock through the development of different side surfaces and different measuring lines of the apparent resistivity profile.
The high-density resistivity method is also a quadrupole method in nature, and comprises the advantages of the quadrupole method and makes up for the disadvantages of the quadrupole method. In the test process, a resistivity-time curve (figure 9) and a resistivity-strain curve (figures 10 and 11) can be established by using resistivity data of a point A (figure 6) acquired by a high-density resistivity instrument, the change characteristics of single-stage loading and graded loading creep resistivity are analyzed, the precursor characteristics of the change of the resistivity of the point A at the accelerated creep stage of the rock are described, and the development trend of the main fracture of the rock is analyzed according to the resistivity data acquired by electrodes arranged on different measuring lines on different sides of the rock.
The apparent resistivity values of all measuring lines on the same side of the rock test piece in the single-stage loading and graded loading creep rupture process are obtained by using a Wenner symmetrical quadrupole device (w-alpha), the change characteristics of the apparent resistivity anisotropy along with the depth and the stress are researched, 6 groups of apparent resistivity data pairs are extracted from the rock test piece, each group of data pairs consists of 3 apparent resistivities of the measuring lines formed by micro-drilled holes 41A, 41B and 41D, and the apparent resistivity data pairs respectively correspond to 6 effective depths (figure 6). The apparent resistivity anisotropy coefficient lambda and the included angle alpha between the fracture dominant direction and the pressurizing axis direction are calculated by formulas such as a Chen Peak (2000) and the like, namely:
wherein:
L＝ρs1 -2+ρs2 -2，
M＝ρs1 -2-ρs2 -2，
Q＝2ρs3 -2-L，
α＝0.5*[arctan(Q/M)+kπ]，k＝0，1，2，3，
where rhos1，ρs2，ρs3Respectively apparent resistivity values along the lines measured from the boreholes 41A, 41B, 41D.
Analyzing the change of the original electrical anisotropy of the rock test piece along with the depth;
analyzing the change relation of the rock apparent resistivity anisotropy coefficient along with stress;
analyzing the difference between the maximum lambda and the minimum lambda under different stresses at different depths, and describing the main depths generated by the fracture surfaces and the relative high and low development rates;
and analyzing the trend change of the azimuth angle alpha of the anisotropic main shaft of the apparent resistivity at different depths along with the increase of the stress, and describing the generation and development directionality of the fracture surface.
Wennan symmetric quadrupole device (w- α) principle (FIG. 3): when measured, AM-NB is an electrode spacing, A, B, M, N moves to the right simultaneously point by point, resulting in a first section line. Next, AM, MN, NB increased by one electrode spacing, A, B, M, N moved to the right simultaneously point by point, resulting in another cross-sectional line. The scanning measurement is continued, and the inverted trapezoidal section is obtained.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (5)
1. A method for calibrating creep damage and fracture surfaces of rocks by using high-density resistivity is characterized by comprising the following steps:
s1: respectively drilling a plurality of rows of drill holes on three side surfaces of a cuboid rock test piece by using electric drills;
s2: installing an electrode wire in each bore;
s3: carrying out 24-hour water saturation treatment on the rock test piece with the electrode wire under a vacuum condition;
s4: performing surface water sealing treatment on the rock test piece obtained in the step S3;
s5: performing surface cleaning on the side surface without the drilled hole of the rock test piece obtained in the step S4, and installing a strain gauge in the center of the side surface, wherein the strain gauge is connected with a static strain measuring instrument;
s6: connecting all the electrode wires with a high-density resistivity meter;
s7: placing the rock test piece obtained in the step S6 on a press machine, and filling plastic insulation plates between the upper and lower surfaces of the rock test piece and the contact surfaces of the upper and lower pressing plates of the press machine;
s8: measuring initial resistivity data when the load is not applied;
s9: starting a press machine to start a test;
s10: storing the data collected by the high-density resistivity instrument and the stress-strain data of the rock test piece in real time until the rock test piece is crushed, and stopping the test;
s11: data processing: transmitting the measurement data stored in the electrical method instrument to a computer, processing the measurement data by the computer, and drawing a resistivity-time curve, a resistivity-strain curve, a stress-strain curve, a time-strain curve and apparent resistivity profile maps of the rock test piece in different directions and different time nodes;
s12: and comprehensively calibrating the creep damage and potential fracture surface development conditions of the rock according to the obtained resistivity-time curve, resistivity-strain curve, stress-strain curve, time-strain curve and rock apparent resistivity profile.
2. The method for calibrating the creep damage and fracture surface of the rock by using the high-density resistivity according to claim 1, wherein the method comprises the following steps:
in the step S1, each rock specimen has four rows of drill holes on its side surface, where one row of drill holes is parallel to the height direction of the rock specimen, one row of drill holes is perpendicular to the height direction of the rock specimen, the other two rows of drill holes respectively form 45 ° with the height direction of the rock specimen, the hole diameter of the drill hole is 1mm, the depth is 10mm, and the distance between two adjacent drill holes in each row of drill holes is 5 mm.
3. The method for calibrating the creep damage and fracture surface of the rock by using the high-density resistivity according to claim 1, wherein the method comprises the following steps:
in the step S2, graphite conductive adhesive is uniformly coated on the electrode wire, inserted into the drilled hole, and completely cured after being placed in a dry and ventilated place for 24 hours.
4. The method for calibrating the creep damage and fracture surface of the rock by using the high-density resistivity according to claim 1, wherein the method comprises the following steps:
in the step S4, epoxy resin is used as the water sealing material, and the ratio of epoxy resin to curing agent is 3: 1, then placing the rock test piece with the surface water sealing treatment in a dry and ventilated place for 24h to be completely solidified:
in the step S5, the surface of the rock specimen obtained in the step S4, which does not have the drilled hole, is scraped by a scraper to remove the epoxy resin in the center of the surface, and then is polished by coarse and fine sandpaper in sequence, and finally the polished area is cleaned by alcohol, and a strain gauge and a connection terminal are attached, and one end of a lead is connected with the strain gauge through the connection terminal, and the other end of the lead is connected with a static strain gauge.
5. The method for calibrating the creep damage and fracture surface of the rock by using the high-density resistivity according to claim 1, wherein the method comprises the following steps:
in the step S5, the strain gauge is bonded and fixed to the rock surface, and the transverse strain gauge is perpendicular to the height direction of the rock specimen, and the longitudinal strain gauge is parallel to the height direction of the rock specimen.
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| CN114323910B (en) * | 2021-12-06 | 2024-02-27 | 东北大学 | Manufacturing and creep shear test method for mud-containing interlayer rock joint sample |
| CN115655379B (en) * | 2022-11-16 | 2023-03-31 | 山东大学 | High-density electrical monitoring device, system and method for stone cultural relic body |
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