CN111751214A - Deep soft rock anchoring interface drawing experimental device and method - Google Patents
Deep soft rock anchoring interface drawing experimental device and method Download PDFInfo
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- CN111751214A CN111751214A CN202010677624.2A CN202010677624A CN111751214A CN 111751214 A CN111751214 A CN 111751214A CN 202010677624 A CN202010677624 A CN 202010677624A CN 111751214 A CN111751214 A CN 111751214A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0003—Steady
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0005—Repeated or cyclic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0017—Tensile
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A10/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE at coastal zones; at river basins
- Y02A10/23—Dune restoration or creation; Cliff stabilisation
Abstract
The invention discloses a deep soft rock anchoring interface drawing experimental device and an experimental method, wherein the deep soft rock anchoring interface drawing experimental device comprises a test piece clamp, a drawing device and a drawing device, wherein the test piece clamp is used for fixing a soft rock test piece in an internal cavity of the test piece clamp; the first anchor rod drawing instrument is used for clamping the soft rock test piece to apply boundary constraint pressure; the anchor rod is inserted into the central circular hole of the soft rock test piece and is solidified with the epoxy resin mortar body poured in the central circular hole; the second anchor rod drawing instrument is used for applying upward drawing force to the anchor rod until the anchor rod and the epoxy resin mortar body are drawn out; and the monitoring components are arranged inside and on the outer wall of the soft rock test piece and used for monitoring the drawing resistance and the deformation characteristic of the soft rock test piece under different boundary constraint pressure conditions. The invention has the advantages of easy operation, stable integral connection and uniform stress, and operators can control the experimental process, accurately and circularly load and unload a research test piece and control the constraint stress, ensure the accuracy of the measurement result, and is beneficial to improving the field work efficiency and saving the cost.
Description
Technical Field
The invention belongs to the technical field of uplift tests, and particularly relates to a deep soft rock anchoring interface drawing experimental device and an experimental method.
Background
Along with the gradual deep mining of coal mines, the problems of the analysis of the breaking, crushing, swelling and deformation mechanism, the deformation prediction and the control of the surrounding rock of deep soft rock roadways are more and more prominent. The large deformation of the deep roadway surrounding rock can be divided into a physicochemical expansion type, a stress expansion type and a structural deformation type, wherein the stress expansion type surrounding rock deformation can be respectively pure shear failure, bending failure and tension-shear slip failure, and has obvious rheological property. The problem of stability control of surrounding rocks of deep soft rock roadways is difficult to solve, and on one hand, under the action of dual severe conditions of high ground stress and soft rock, the mechanism of crushing, swelling, deformation, damage and evolution of the surrounding rocks is not clear enough. The deep rock mass and the shallow rock mass are mainly different in the difference of stress environments where the rock masses are located, and the difference of the stress environments causes the difference of physical and mechanical properties of the rock masses, so that the obvious difference of the strength and the deformation properties of the rock masses is caused.
Due to the outstanding contradiction between high occurrence ground stress and low strength of surrounding rock mass, the stress concentration and stress redistribution caused after deep roadway excavation can cause rock mass failure and instability (entering a post-peak fracture state) in a large range, and the roadway surrounding rock can also generate strong crushing, swelling and deformation due to rheological damage and fracture instability. On the other hand, the existing support forms and support theories are limited, and particularly, the research and design theories of the anchoring mechanism still lag behind the engineering practice. In the deep soft rock anchoring engineering, an anchor rod penetrates through a rock body to form an anchoring body with high integrity, however, the difference of the physical and mechanical properties of the anchor rod and the soft rock is large, so that the deformation of the contact surface of the anchor rod and the soft rock is inconsistent, and the obvious uncoordinated deformation characteristic is shown, so that the research on an anchoring interface mechanical mechanism and an interface model is particularly important.
Deep research deep soft rock is broken to expand and is out of shape ageing characteristic, reveals deep soft rock tunnel country rock is broken to expand and is out of shape deformation evolution mechanism and anchor interface failure mechanism, seeks the practical theory who solves the broken swelling deformation unstability problem of deep soft rock and is the basic work that needs to be carried out in the deep soft rock engineering urgently.
Disclosure of Invention
Based on the defects of the prior art, the technical problem to be solved by the invention is to provide the deep soft rock anchoring interface drawing experimental device and the deep soft rock anchoring interface drawing experimental method, the operation is easy and convenient, the integral connection is stable, the stress is uniform, the safety and the reliability are realized, an operator can control the experimental process, the cyclic loading and unloading of a research test piece and the control of the constraint stress are accurate, the accuracy of a measurement result is ensured, the field work efficiency is improved, and the cost is saved.
In order to solve the technical problems, the invention is realized by the following technical scheme: the invention provides a deep soft rock anchoring interface drawing experimental device which comprises a test piece clamp, a bearing frame and a drawing experimental device, wherein the test piece clamp consists of two semi-circular arc-shaped clamp bodies, is fixed in the bearing frame and is used for fixing a soft rock test piece in an inner cavity of the test piece clamp; the first anchor rod drawing instrument is arranged on two sides of the test piece clamp and used for clamping the soft rock test piece to apply boundary constraint pressure; the anchor rod is inserted into the central circular hole of the soft rock test piece along the central axis direction of the soft rock test piece and is solidified with the epoxy resin mortar body poured in the central circular hole; the second anchor rod drawing instrument is arranged at the top of the bearing frame, is connected with the upper part of the anchor rod extending out of the bearing frame and is used for applying upward drawing force to the anchor rod until the anchor rod and the epoxy resin mortar body are drawn out; and the monitoring components are arranged inside and on the outer wall of the soft rock test piece and used for monitoring the drawing resistance and the deformation characteristic of the soft rock test piece under different boundary constraint pressure conditions.
Optionally, the semi-circular arc-shaped fixture body comprises a fixed outer wall, fixed legs extending radially along two edges of the fixed outer wall, and an arc-shaped reinforcing end connected between the fixed outer wall and the fixed legs, wherein two pressure anchoring holes are equidistantly arranged on the fixed legs; and the fixing clamp bolt penetrates through the pressurizing anchoring hole to be connected with the first anchor rod drawing instrument.
Further, an anchor rod tray is arranged between the bearing frame and the second anchor rod drawing instrument, the anchor rod tray is composed of an upper layer pressure-bearing sheet, a middle layer pressure-bearing sheet and a lower layer pressure-bearing sheet which are prefabricated together, and a through hole for the anchor rod to pass through is reserved in the center positions of the upper layer pressure-bearing sheet, the middle layer pressure-bearing sheet and the lower layer pressure-bearing sheet; the upper layer pressure-bearing sheet and the lower layer pressure-bearing sheet are annular, and the middle layer pressure-bearing sheet is connected between the upper layer pressure-bearing sheet and the lower layer pressure-bearing sheet and is conical; the diameter of upper bearing piece is less than the diameter of lower floor's bearing piece, just upper bearing piece with the appearance is drawn to the second stock contacts, lower floor's bearing piece with bear the frame and contact.
Optionally, the monitoring component includes: the pressure sensor is pasted on the outer side of the soft rock test piece, arranged opposite to the inner side of the test piece clamp and used for monitoring the boundary constraint pressure of the soft rock test piece after the first anchor rod drawing instrument fastens the test piece clamp; the strain gauge is arranged in the soft rock test piece and used for monitoring the strain change rule of the soft rock test piece; and the data acquired by the pressure sensor and the strain gauge are transmitted to a control center through a data acquisition line.
Optionally, the strain gauges are divided into a group a of strain gauges and a group B of strain gauges, and each group of 2 strain gauges is vertically arranged; the group A strain gauge and the group B strain gauge are arranged on the inner side of a central circular hole of the soft rock test piece; the group A strain gauge and the soft rock are firmly bonded together through epoxy resin glue, the strain change rule of the soft rock is monitored, and a lubricant is smeared on the other surface of the group A strain gauge and used for preventing epoxy resin mortar body from being bonded with the group A strain gauge; the group B strain gauge and the inner wall of the soft rock are temporarily bonded and fixed through a common double-sided adhesive tape, the group B strain gauge and the soft rock do not deform together, and after the central round hole is grouted, the epoxy resin mortar body is bonded with the group B strain gauge.
Further, the bearing frame comprises an upper bearing plate and a lower bearing plate which are arranged in parallel, and the two bearing plates are fixedly connected through a bearing plate fixing bolt; the test piece fixture is fixed between the two bearing plates.
The invention also provides an experimental method of the deep soft rock anchoring interface drawing experimental device, which comprises the following steps:
s10: firstly, manufacturing a soft rock test piece, collecting a sample from a deep soft rock engineering site, processing a disc-shaped soft rock test piece, and drilling a central circular hole in the circle center of the soft rock test piece by using a drilling machine;
s20: sticking a strain gauge in a central circular hole of each soft rock test piece, wherein the group A strain gauges and the soft rock are firmly stuck together through epoxy resin glue, and monitoring the strain change rule of the soft rock; the group B strain gauge and the inner wall of the soft rock are temporarily bonded and fixed through a common double-sided adhesive tape, the group B strain gauge and the soft rock do not deform together, after epoxy resin mortar is poured into a central round hole of the soft rock test piece, the slurry is bonded with the group B strain gauge, the epoxy resin mortar is poured into the central round hole of the soft rock test piece, then the anchor rod is inserted into the middle position of the slurry, and after the slurry is solidified, the anchor rod-soft rock test piece is demoulded;
s30: pasting a pressure sensor on the outer side of a sample, placing an anchor rod-soft rock test piece into a test piece clamp, fastening two ends of the test piece clamp by using bolts, installing a first anchor rod drawing instrument at the other end of each bolt, placing the test piece clamp and the anchor rod-soft rock test piece between an upper bearing plate and a lower bearing plate, and fastening two ends of the upper bearing plate and the lower bearing plate by using bolts;
s40: installing a second anchor rod drawing instrument at the top end of the anchor rod, applying drawing load to the first anchor rod drawing instrument to realize the application of boundary pressure to the interior of the soft rock test piece, gradually fastening the test piece clamp, observing the pressure sensor, keeping the load unchanged after the pressure reaches the set first-stage boundary pressure, starting the second anchor rod drawing instrument, slowly increasing the drawing force, monitoring the change of the deformation sensor until the anchor rod is drawn out, and finishing the experiment;
s50: preliminarily designing 3 pressure levels, respectively applying boundary pressure to the second level and the third level to the interior of the soft rock test piece, and monitoring the drawing resistance and the deformation characteristic of the soft rock test piece under different boundary pressure conditions;
s60: performing a plurality of groups of drawing experiments, and setting the length of the anchoring section to be 200mm, 400mm and 600 mm; and (4) sequentially carrying out anchor rod-soft rock interface drawing experiments with different anchoring lengths and different constraint pressures.
In addition, according to the anchoring forces of different anchoring bodies and different boundary pressures obtained in the experiment, an anchor rod-soft rock interface cyclic loading and unloading drawing experiment scheme is formulated, cyclic loading 5 stages are preliminarily formulated, and each stage is held for 12 hours;
firstly, carrying out a test piece circulation loading and unloading drawing experiment of an anchoring section of 200mm, wherein the embedding of a pressure sensor is the same as the flow, firstly, loading a first-stage tensile force on an anchoring body, then, holding the anchoring body for 12 hours, compensating the loss of the anchoring force every half hour for the first 2 hours, then, unloading and standing for 4 hours, observing the change rule of the viscoplasticity shear strain of the structural surface, then, continuously loading a second-stage tensile force, compensating the loss of the anchoring force in the same way, and so on until the tensile force load of the 5 th stage is loaded, observing the change rule of the shear stress strain of the anchoring interface, and observing the damage characteristic of the anchoring interface;
and sequentially carrying out anchor rod-soft rock interfaces with different anchoring lengths and different constraint pressures to develop a drawing experiment, measuring the change curves of the shearing strains of the slurry interfaces and the soft rock interfaces in different regions along with time, and observing the macro-micro fracture characteristics of the slurry-soft rock interfaces.
Therefore, the deep soft rock anchoring interface drawing experimental device and the experimental method are easy and convenient to operate, stable in integral connection, uniform in stress, safe and reliable, operators can control the experimental process, accurate in measurement result, beneficial to improvement of field working efficiency and cost saving, and accurate in cycle loading and unloading of a test piece and control of constraint stress. Aiming at the failure engineering background of the deep soft rock anchoring body, carrying out experimental research from the research direction of anchor rod-soft rock uncoordinated deformation characteristics, and researching the failure evolution rule and the fracture characteristic of a soft rock anchoring interface by adopting an independently developed soft rock anchoring body drawing experimental system; developing scientific research attack from the crushing, swelling, deformation and aging characteristic direction of the soft rock, and adopting a front-edge continuous-discontinuous unit method to deduce the deep soft rock crushing, swelling, deformation and evolution process; and finally, constructing a typical deep soft rock roadway numerical model by adopting a continuous-discontinuous unit method, and analyzing the action mechanism and the failure evolution rule of the deep soft rock roadway surrounding rock crushing, swelling and deformation group anchors.
The foregoing description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly understood, the present invention may be implemented in accordance with the content of the description, and in order to make the above and other objects, features, and advantages of the present invention more clearly understood, the following detailed description is given in conjunction with the preferred embodiments, together with the accompanying drawings.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments will be briefly described below.
FIG. 1 is a schematic structural diagram of a deep soft rock anchoring interface drawing experimental device according to a preferred embodiment of the present invention;
FIG. 2 is a front exploded view of FIG. 1;
fig. 3 is a schematic view of the connection of a second anchor puller, anchor tray and anchor of the present invention;
fig. 4 is a schematic structural view of the anchor rod tray of the present invention;
FIG. 5 is a schematic view of a pressure sensor of the present invention disposed on a soft rock test piece;
FIG. 6 is a schematic view of a strain gage of the present invention disposed on a soft rock test piece;
FIG. 7 is a schematic view of the structure of the specimen holder of the present invention;
fig. 8 is a schematic layout of a second anchor puller of the present invention;
FIG. 9 is a drawing experimental diagram in which the length of the anchoring section is set to 200 mm;
FIG. 10 is a drawing experimental plot with the anchor segment length set to 400 mm;
FIG. 11 is a drawing experimental drawing in which the length of the anchor section is set to 600 mm;
fig. 12 is a front view of fig. 11.
In the figure, 1-second anchor puller (HC-50 type anchor puller); 2-bearing plate fixing bolt; 3-an upper carrier plate; 4-anchor rod tray; 5-a test piece clamp; 6-a deformed steel anchor rod; 7-soft rock test piece; 8-first anchor rod drawing instrument (HC-10 type anchor rod drawing instrument); 9-fixing the clamp bolt; 10-a lower carrier plate; 11-a pressure sensor; 12-strain gage; 13-data acquisition line; 4-1-upper bearing sheet; 4-2-middle layer pressure-bearing sheet; 4-3-lower layer pressure-bearing sheet; 5-1-fixing the outer wall; 5-2-fixed feet; 5-3-reinforcement ends; 5-4-pressurized anchoring holes; 12-1-group A strain gage; group 12-2-B strain gages.
Detailed Description
Other aspects, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which form a part of this specification, and which illustrate, by way of example, the principles of the invention. In the referenced drawings, the same or similar components in different drawings are denoted by the same reference numerals.
As shown in fig. 1 to 12, the deep soft rock anchoring interface drawing experimental device of the present invention mainly includes an HC-50 type anchor rod drawing instrument (second anchor rod drawing instrument) 1, bearing plate fixing bolts 2, an upper bearing plate 3, an anchor rod tray 4, a test piece clamp 5, a deformed steel anchor rod 6, a soft rock test piece 7, an HC-10 type anchor rod drawing instrument (first anchor rod drawing instrument) 8, fixing clamp bolts 9, a lower bearing plate 10, a bonding pressure sensor 11, a strain gauge 12, and a data acquisition line 13, wherein the upper side drawing power of the experimental device is derived from the HC-50 type anchor rod drawing instrument 1, the anchor rod tray 4 is arranged at the lower side of the HC-50 type anchor rod drawing instrument 1, the upper connecting part of the deformed steel anchor rod 6 penetrates through the anchor rod tray 4 to be connected with the HC-50 type anchor rod drawing instrument 1, the lower side of the anchor rod tray 4 is arranged on the upper bearing plate 3, four bearing plate fixing bolts 2 are arranged at the periphery (four corners) of the, the upper connecting part of the bearing plate fixing bolt 2 is fixed 3 with the upper bearing plate, and the lower connecting part of the bearing plate fixing bolt 2 is fixed 10 with the lower bearing plate. A test piece clamp 5 is fixed between the upper bearing plate and the lower bearing plate, a soft rock test piece 7 is placed inside the test piece clamp 5, the soft rock test piece 7 is a hollow cylinder test piece, and an inner strain gauge 12 is arranged on the inner wall of a central circular hole of the soft rock test piece 7. And a rod body of the deformed steel bar anchor rod 6 penetrates through a through hole reserved in the center position of the upper bearing plate 3, is inserted into the soft rock test piece 7, and is poured with epoxy resin mortar.
The outer wall of the soft rock test piece 7 is pasted with a pressure sensor 11 and fixed on the inner side of the test piece clamp 5, HC-10 type anchor rod drawing instruments 8 are installed on two sides of the test piece clamp 5, boundary constraint pressure is applied to the soft rock test piece 7 by drawing a fixed clamp bolt 9, the test constraint pressure is preliminarily set to be 3 levels, and after the pressure is stable, the reading of the corresponding transformer is cleared; and then starting the HC-50 type anchor rod drawing instrument 1, slowly increasing the drawing force, and monitoring the data change of each strain gauge and the change of the anchoring force until the anchor rod and the slurry are drawn out. The data collected by the pressure sensor 11 and the strain gauge 12 are transmitted to the control center through a data collection line 13.
As shown in figure 4, the anchor rod tray 4 of the invention is composed of an upper bearing plate 4-1, a middle bearing plate 4-2 and a lower bearing plate 4-3, which are prefabricated together, an anchor rod through hole is reserved in the center of the upper bearing plate, the middle bearing plate and the lower bearing plate, and the size of the anchor rod through hole is matched with the outer diameter of a deformed steel anchor rod 6. The upper-layer pressure-bearing sheet 4-1 and the lower-layer pressure-bearing sheet 4-3 are annular, the middle-layer pressure-bearing sheet 4-2 is connected between the upper-layer pressure-bearing sheet and the lower-layer pressure-bearing sheet and is conical, the diameter of the upper-layer pressure-bearing sheet 4-1 is smaller than that of the lower-layer pressure-bearing sheet 4-3, the upper-layer pressure-bearing sheet 4-1 is in contact with the HC-50 type anchor rod drawing instrument 1, and the lower-layer pressure-bearing sheet 4-3 is in contact with the upper bearing.
As shown in fig. 6, the strain gauge 12 is divided into an a group strain gauge 12-1 and a B group strain gauge 12-2, each group of 2 strain gauges is vertically arranged, the a group strain gauge and the B group strain gauge are arranged on the inner side of a central circular hole of the soft rock test piece 7, the a group strain gauge 12-1 and the soft rock are firmly bonded together through epoxy resin glue, the strain change rule of the soft rock is monitored, and a lubricant is coated on the other surface of the a group strain gauge 12-1 to prevent subsequent epoxy resin slurry from being bonded with the a group strain gauge 12-1. The group B strain gauge 12-2 and the inner wall of the soft rock are temporarily bonded and fixed through a common double-sided adhesive tape, the group B strain gauge 12-2 and the soft rock do not deform together, and after grouting is carried out in the hole, slurry is bonded with the group B strain gauge 12-2.
As shown in FIG. 7, the semi-circular arc-shaped clamp body of the test piece clamp 5 comprises a fixed outer wall 5-1, two fixed legs 5-2 and a reinforced end 5-3, wherein two fixed legs 5-2 are arranged on two sides of the fixed outer wall 5-1, 2 pressurizing anchor holes 5-4 are equidistantly arranged on the fixed legs 5-2, and the fixed outer wall 5-1 is connected with the fixed legs 5-2 by additionally arranging the arc-shaped reinforced end 5-3 for reinforcement. The fixing clamp bolt 9 penetrates through the pressurizing anchoring holes 5-4, the thickness T of the fixing outer wall 5-1 is 20mm, the height H of the fixing leg 5-2 is 200mm, the length N is 100mm, the inner diameter R of a cavity defined by the two fixing outer walls 5-1 is 220mm, and a compression joint with the width Z being 5mm is reserved between the two attached fixing legs 5-2.
In addition, the HC-10 type anchor rod drawing instrument of the invention has the following main parameters: oil pump centre bore diameter 27mm, oil pump stroke 60mm, measuring range: 0-100KN and 7.5KG in weight; the HC-50 type anchor rod drawing instrument has the following main parameters: oil pump centre bore diameter 60mm, oil pump stroke 120mm, measuring range: 0-500KN and 29KG in weight; both instruments are manufactured by Beijing Haichang high tech Co. The deformed steel anchor rod 6 of the invention adopts a deformed steel anchor rod with the diameter phi of 18.
The soft rock test piece 7 is a disc-shaped test piece which is obtained by collecting a test sample from a deep soft rock engineering site, processing the test sample into a diameter phi 220mm and a thickness L which is 100mm, and drilling a through hole with r which is 22mm at the center of a circle by a drilling machine.
As shown in fig. 9-12, the experimental operation flow of the anchor rod-soft rock drawing experiment by using the experimental device is as follows: the anchoring section length is 100 mm: firstly, a soft rock test piece 7 is manufactured, a sample is collected from a deep soft rock engineering site and processed into a disc-shaped sample with the diameter phi of 220mm and the thickness L of 100mm, and then a drilling machine is adopted to drill a central round hole with the thickness r of 22mm at the center of a circle.
Secondly, placing the soft rock test piece 7 into the test piece fixture 5 for fixing, and adhering a strain gauge 12 in a central round hole of each test piece, wherein the group A strain gauges 12-1 and the soft rock are firmly adhered together through epoxy resin glue, monitoring the strain change rule of the soft rock, and smearing a lubricant on the other side of the group A strain gauge 12-1 to prevent subsequent epoxy resin slurry from adhering to the group A strain gauge 12-1. And then temporarily bonding and fixing the B group strain gauge 12-2 and the inner wall of the soft rock through a common double-sided adhesive tape to prevent the B group strain gauge 12-2 and the soft rock from jointly deforming, after grouting in a hole, bonding the slurry with the B group strain gauge 12-2, pouring epoxy resin mortar in a soft rock test piece 7, then inserting a phi 18 deformed steel anchor rod 6 with the length of 400mm in the middle of the slurry, demolding the anchor rod-soft rock test piece after the slurry is solidified, and then bonding a pressure sensor 11 on the outer side of the test piece. The anchor rod-soft rock test piece is placed in a test piece clamp 5, two ends of the test piece clamp 5 are fastened through bolts, an HC-10 type anchor rod drawing instrument 8 is installed at the other end of each bolt, the clamp and the anchor rod-soft rock test piece are placed between an upper bearing plate and a lower bearing plate, and two ends of the upper bearing plate and the lower bearing plate are fastened through bolts.
Installing HC-50 type anchor rod drawing instrument 1 at one end of the anchor rod, applying drawing load to HC-10 type anchor rod drawing instrument 8 to realize applying boundary pressure to the interior of the soft rock test piece 7, and preliminarily designing 3 pressure levels in experiments. Firstly, gradually fastening the test piece clamp 5, observing the pressure sensor, keeping the load unchanged when the pressure reaches the set first-stage boundary pressure, starting the HC-50 type anchor rod drawing instrument 1, slowly increasing the drawing force, monitoring the change of the deformation sensor until the anchor rod 6 is drawn out, and finishing the experiment. And respectively applying boundary pressure to the second level and the third level to the interior of the soft rock test piece 7, and monitoring the drawing resistance and the deformation characteristic of the soft rock test piece 7 under different boundary pressure conditions.
Fourthly, performing a plurality of groups of drawing experiments, and setting the length of the anchoring section to be 200mm, 400mm and 600 mm; and (4) sequentially carrying out anchor rod-soft rock interface drawing experiments with different anchoring lengths and different constraint pressures. Firstly, processing a drilled rock sample with the diameter phi of 220mm into a disc-shaped test sample with the thickness L equal to 100mm, drilling a central circular hole with the diameter r equal to 22mm at the center of the circle, putting 2 soft rock disc test samples into a test sample clamp 5, fixing and overlapping the soft rock disc test samples into a combined test sample with an anchoring section of 200mm, and manufacturing a 400mm and 600mm combined test sample by analogy; the rest of the operation is the same as the above;
and (3) according to the anchoring forces of different anchoring bodies and different boundary pressures obtained in the experiment, establishing an anchor rod-soft rock interface cyclic loading and unloading drawing experiment scheme, initially establishing 5 stages of cyclic loading, and holding the load for 12 hours at each stage.
Firstly, a test piece circulation loading and unloading drawing experiment with an anchoring section of 200mm is carried out. The embedding of the sensor is the same as the process, firstly, a first-stage tensile force is loaded on the anchoring body, then, the anchoring body is kept loaded for 12 hours, the first 2 hours, the loss of the anchoring force is compensated every half hour, then, the anchoring body is unloaded and is kept still for 4 hours, the change rule of the viscoplasticity shear strain of the structural surface is observed, then, a second-stage tensile force is continuously loaded, the loss of the anchoring force is compensated in the same way, the process is repeated until the 5 th-stage tensile force load is loaded, the change rule of the shear stress strain of the anchoring interface is observed, and the damage characteristic of the anchoring interface is.
And secondly, sequentially carrying out anchor rod-soft rock interfaces with different anchoring lengths and different constraint pressures to develop a drawing experiment, measuring the change curves of the shearing strains of the slurry interfaces and the soft rock interfaces in different regions along with time, and observing the macroscopic and microscopic fracture characteristics of the slurry-soft rock interfaces.
While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Claims (8)
1. The utility model provides an experimental apparatus is drawn at dark soft rock anchor interface which characterized in that: the method comprises the following steps:
the test piece clamp consists of two semi-circular arc clamp bodies, is fixed in the bearing frame and is used for fixing the soft rock test piece in an inner cavity of the test piece clamp;
the first anchor rod drawing instrument is arranged on two sides of the test piece clamp and used for clamping the soft rock test piece to apply boundary constraint pressure;
the anchor rod is inserted into the central circular hole of the soft rock test piece along the central axis direction of the soft rock test piece and is solidified with the epoxy resin mortar body poured in the central circular hole;
the second anchor rod drawing instrument is arranged at the top of the bearing frame, is connected with the upper part of the anchor rod extending out of the bearing frame and is used for applying upward drawing force to the anchor rod until the anchor rod and the epoxy resin mortar body are drawn out;
and the monitoring components are arranged inside and on the outer wall of the soft rock test piece and used for monitoring the drawing resistance and the deformation characteristic of the soft rock test piece under different boundary constraint pressure conditions.
2. The deep soft rock anchoring interface pulling experiment device as claimed in claim 1, wherein the semi-circular arc-shaped fixture body comprises a fixed outer wall, fixed legs extending radially along two edges of the fixed outer wall, and an arc-shaped reinforcing end connected between the fixed outer wall and the fixed legs, and two pressurized anchoring holes are equidistantly arranged on the fixed legs;
and the fixing clamp bolt penetrates through the pressurizing anchoring hole to be connected with the first anchor rod drawing instrument.
3. The deep soft rock anchoring interface drawing experimental device as claimed in claim 1, wherein an anchor rod tray is further arranged between the bearing frame and the second anchor rod drawing instrument, the anchor rod tray is composed of an upper bearing plate, a middle bearing plate and a lower bearing plate which are prefabricated together, and a through hole for the anchor rod to pass through is reserved in the center positions of the upper bearing plate, the middle bearing plate and the lower bearing plate;
the upper layer pressure-bearing sheet and the lower layer pressure-bearing sheet are annular, and the middle layer pressure-bearing sheet is connected between the upper layer pressure-bearing sheet and the lower layer pressure-bearing sheet and is conical;
the diameter of upper bearing piece is less than the diameter of lower floor's bearing piece, just upper bearing piece with the appearance is drawn to the second stock contacts, lower floor's bearing piece with bear the frame and contact.
4. The deep soft rock anchoring interface pullout experimental apparatus of claim 1, wherein the monitoring assembly includes:
the pressure sensor is pasted on the outer side of the soft rock test piece, arranged opposite to the inner side of the test piece clamp and used for monitoring the boundary constraint pressure of the soft rock test piece after the first anchor rod drawing instrument fastens the test piece clamp;
the strain gauge is arranged in the soft rock test piece and used for monitoring the strain change rule of the soft rock test piece;
and the data acquired by the pressure sensor and the strain gauge are transmitted to a control center through a data acquisition line.
5. The deep soft rock anchoring interface pulling experiment device according to claim 4, wherein the strain gauges are divided into a group A strain gauge and a group B strain gauge, and each group has 2 strain gauges and is vertically arranged; the group A strain gauge and the group B strain gauge are arranged on the inner side of a central circular hole of the soft rock test piece;
the group A strain gauge and the soft rock are firmly bonded together through epoxy resin glue, the strain change rule of the soft rock is monitored, and a lubricant is smeared on the other surface of the group A strain gauge and used for preventing epoxy resin mortar body from being bonded with the group A strain gauge;
the group B strain gauge and the inner wall of the soft rock are temporarily bonded and fixed through a common double-sided adhesive tape, the group B strain gauge and the soft rock do not deform together, and after the central round hole is grouted, the epoxy resin mortar body is bonded with the group B strain gauge.
6. The deep soft rock anchoring interface pulling test device of claim 1, wherein the bearing frame comprises an upper bearing plate and a lower bearing plate which are arranged in parallel with each other, and the two bearing plates are fixedly connected through bearing plate fixing bolts; the test piece fixture is fixed between the two bearing plates.
7. An experimental method of the deep soft rock anchoring interface pulling experimental device according to any one of claims 1 to 6, characterized by comprising the following steps:
s10: firstly, manufacturing a soft rock test piece, collecting a sample from a deep soft rock engineering site, processing a disc-shaped soft rock test piece, and drilling a central circular hole in the circle center of the soft rock test piece by using a drilling machine;
s20: sticking a strain gauge in a central circular hole of each soft rock test piece, wherein the group A strain gauges and the soft rock are firmly stuck together through epoxy resin glue, and monitoring the strain change rule of the soft rock; the group B strain gauge and the inner wall of the soft rock are temporarily bonded and fixed through a common double-sided adhesive tape, the group B strain gauge and the soft rock do not deform together, after epoxy resin mortar is poured into a central round hole of the soft rock test piece, the slurry is bonded with the group B strain gauge, the epoxy resin mortar is poured into the central round hole of the soft rock test piece, then the anchor rod is inserted into the middle position of the slurry, and after the slurry is solidified, the anchor rod-soft rock test piece is demoulded;
s30: pasting a pressure sensor on the outer side of a sample, placing an anchor rod-soft rock test piece into a test piece clamp, fastening two ends of the test piece clamp by using bolts, installing a first anchor rod drawing instrument at the other end of each bolt, placing the test piece clamp and the anchor rod-soft rock test piece between an upper bearing plate and a lower bearing plate, and fastening two ends of the upper bearing plate and the lower bearing plate by using bolts;
s40: installing a second anchor rod drawing instrument at the top end of the anchor rod, applying drawing load to the first anchor rod drawing instrument to realize the application of boundary pressure to the interior of the soft rock test piece, gradually fastening the test piece clamp, observing the pressure sensor, keeping the load unchanged after the pressure reaches the set first-stage boundary pressure, starting the second anchor rod drawing instrument, slowly increasing the drawing force, monitoring the change of the deformation sensor until the anchor rod is drawn out, and finishing the experiment;
s50: preliminarily designing 3 pressure levels, respectively applying boundary pressure to the second level and the third level to the interior of the soft rock test piece, and monitoring the drawing resistance and the deformation characteristic of the soft rock test piece under different boundary pressure conditions;
s60: performing a plurality of groups of drawing experiments, and setting the length of the anchoring section to be 200mm, 400mm and 600 mm; and (4) sequentially carrying out anchor rod-soft rock interface drawing experiments with different anchoring lengths and different constraint pressures.
8. The deep soft rock anchoring interface drawing experiment method according to claim 7, wherein according to the anchoring forces under different anchoring bodies and different boundary pressures obtained by the experiment, an anchor rod-soft rock interface cyclic loading and unloading drawing experiment scheme is formulated, and a cyclic loading 5 stage is preliminarily formulated, and each stage is held for 12 hours;
firstly, carrying out a test piece circulation loading and unloading drawing experiment of an anchoring section of 200mm, wherein the embedding of a pressure sensor is the same as the flow, firstly, loading a first-stage tensile force on an anchoring body, then, holding the anchoring body for 12 hours, compensating the loss of the anchoring force every half hour for the first 2 hours, then, unloading and standing for 4 hours, observing the change rule of the viscoplasticity shear strain of the structural surface, then, continuously loading a second-stage tensile force, compensating the loss of the anchoring force in the same way, and so on until the tensile force load of the 5 th stage is loaded, observing the change rule of the shear stress strain of the anchoring interface, and observing the damage characteristic of the anchoring interface;
and sequentially carrying out anchor rod-soft rock interfaces with different anchoring lengths and different constraint pressures to develop a drawing experiment, measuring the change curves of the shearing strains of the slurry interfaces and the soft rock interfaces in different regions along with time, and observing the macro-micro fracture characteristics of the slurry-soft rock interfaces.
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