CN110940693A - Test method for evaluating freezing resistance of fractured rock mass - Google Patents
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Abstract
The invention discloses a test method for evaluating freeze-thaw resistance of fractured rock mass, which can be used for manufacturing fractures with different widths, lengths, inclination angles and groups by self-making fractures in the aspect of the test method, thereby improving the pertinence and applicability of the test; in the aspect of evaluation indexes, the comprehensiveness of the evaluation of the freeze-thaw resistance performance is reflected by establishing a multi-index fused comprehensive freeze-thaw resistance performance evaluation index, and a reference basis is provided for selecting rocks for engineering construction; in the aspect of freeze-thaw resistance, the freeze-thaw resistance of the rock mass under different concentrations and different types of karst solutions can be determined by the method.
Description
Technical Field
The invention belongs to the technical field of evaluation of freezing resistance of fractured rock masses, and particularly relates to a test method for evaluating the freezing resistance of the fractured rock masses.
Background
The alpine region has complex and special geological environmental conditions. First of all. The method is characterized in that the geological structure has strong and complex effects, deep-cut canyon landform is quite developed, and the geological crushing effects of rock mass structure, unloading load, weather and the like are quite strong; meanwhile, the mountains in the areas generally have larger altitude (the average height is more than 1300m, and the local height reaches more than 3000 m), the temperature can reach 20 ℃ in summer, and the temperature can be reduced to-20 ℃ in winter; not only the seasonal temperature change is obvious, but also the temperature difference between day and night in some areas is even 40 ℃, so that the rock mass is subjected to strong freeze thawing and fragmentation; in addition, rainfall is abundant in the areas, water infiltrates into cracks of rock mass, and then hydraulic frost heaving and melt shrinkage effects further aggravate cracking of the cracked rock mass. The slope rock mass is frozen, swelled, cracked and unstable in the circulating freeze thawing process to form collapse and landslide, and is subsequently converted into debris flow again under the external induction action to form a disaster chain, and the long-term effect is very obvious, so that the method has important significance in conveniently, quickly and reasonably testing and evaluating the freeze thawing resistance of the rock mass for evaluating the stability of the slope rock mass, predicting geological disasters and preventing and controlling.
In the aspect of a test method, the traditional test method can only test the freezing and thawing performance of the rock mass, but cannot carry out a test through self-made rock mass cracks, and meanwhile, the freezing and thawing characteristics of the rock mass and the cracks are obtained; in the aspect of evaluation indexes, a traditional test usually obtains a single index, namely a peak intensity index before and after freeze thawing, neglects deformation and damage of rock masses and cracks, and has certain sheet property, for example, in some types of brittle rock masses, although the peak intensity change before and after freeze thawing is not large, a large number of damaged cracks occur inside the brittle rock masses, and large deformation occurs, so that permeability is increased, and adverse effects are brought to engineering construction, so that a freeze-thaw evaluation method with multiple indexes is necessary to be established in a common test. In the aspect of freeze-thaw resistance, the traditional test method only tests and evaluates the influence of water on the freeze-thaw of the rock mass, and does not research the solution with any type and concentration to improve the freeze-thaw resistance of the rock.
Disclosure of Invention
Aiming at the defects in the prior art, the test method for evaluating the freeze-thaw resistance of the fractured rock mass provided by the invention solves the problems that the freeze-thaw characteristics of the fractured rock mass cannot be obtained in the existing test method, the evaluation index obtained by the test is relatively flat, and the freeze-thaw resistance of the fractured rock mass cannot be accurately reflected.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that: a test method for evaluating freeze-thaw resistance of fractured rock mass comprises the following steps:
s1, selecting a rock mass to be tested, and cutting the rock mass into a plurality of fractured rock samples;
s2, putting all fractured rock samples into an oven to be dried to constant weight;
s3, pasting a strain gauge on the dried fractured rock sample, and connecting the strain gauge with the strain gauge through a test line;
s4, soaking the fractured rock sample in a saturated solution, and simulating a saturated fracture;
s5, placing the fractured rock sample with the saturated fractures into a refrigerator, simulating for a plurality of freeze-thaw cycles, and recording strain data in the process of the freeze-thaw cycles through a strain gauge;
s6, determining indexes of the fractured rock sample after different freeze-thaw cycle times according to the recorded strain data;
and S7, calculating a comprehensive index for evaluating the freeze-thaw resistance of the fractured rock mass according to the indexes of the fractured rock samples.
Further, the step S1 is specifically:
selecting rock masses with the same properties, cutting out a plurality of standard rock samples by a water drilling method, and cutting out a seam on each rock sample to simulate the fracture in the rock mass so as to obtain a plurality of fractured rock samples.
Further, in the step S2, the setting method of the oven parameters when the fractured rock sample is placed in an oven and dried to a constant weight is as follows: the oven temperature was set at 105 ℃ and the drying time was set at 48 hours.
Further, the step S3 is specifically:
s31, wiping the surfaces of all fractured rock samples to remove stains, and polishing the fractured rock samples at the fracture positions by using abrasive paper to flatten the surfaces of the fractured rock samples;
s32, pasting a strain gauge in the middle of a crack rock sample with a flat surface, and coating a layer of silicon rubber on the surface of the pasted strain gauge;
s33, connecting one end of the test wire with the strain gauge, and connecting the other end of the test wire with the strain gauge according to a 1/4 bridging method to complete the pasting of the strain gauge and the connection of the strain gauge and the strain gauge;
the middle part of the test wire is fixed on the fractured rock sample through an insulating adhesive tape, and each channel of the strain gauge is connected with a temperature compensation sheet.
Further, the step S4 is specifically:
s41, sequentially soaking the 1/4 fractured rock sample, the 1/2 fractured rock sample and the 3/4 fractured rock sample in a saturated solution for 2 hours to exhaust air in the fractured rock samples;
s42, completely soaking the fractured rock sample with air exhausted in a saturated solution for 24 hours to saturate the fractured rock sample;
and S43, sealing the cracks in the fractured rock sample of the saturated solution by waterproof glue and filling water to simulate the saturated cracks.
Further, the step S5 is specifically:
s51, correcting the sensitivity coefficient of the strain gauge connected with the strain gauge, and checking a connecting circuit of the test line;
s52, placing the fractured rock sample into a refrigerator, simulating freeze-thaw cycles for a plurality of times by adjusting the temperature of the refrigerator, and recording strain data of the fractured rock sample in each freeze-thaw cycle through a strain gauge;
wherein the strain data is the residual strain of the fractured rock sample after each freeze-thaw cycle.
Further, in step S52, the method for simulating the freeze-thaw cycle by adjusting the temperature of the refrigerator specifically includes:
turning on a refrigerator power supply, adjusting the temperature to-20 ℃, turning off the refrigerator power supply after 6 hours to naturally raise the temperature to 20 ℃ so as to complete one freeze-thaw cycle of the fractured rock sample in the refrigerator.
Further, the indexes of the fractured rock sample in the step S6 include a fracture microstrain rate e, a strength loss rate f, and a quality deterioration rate
And a volume expansion ratio lambda.
Further, the fracture microstrain rate epsilon is:
ε＝ε'/W
wherein ε' is the cumulative residual strain, an
Wherein n is the number of freeze-thaw cycles; ε riThe residual strain of the fractured rock sample after the ith freeze-thaw cycle is shown;
w is the fracture width of the fractured rock sample;
the strength loss rate f is:
f＝(σs-σf)/σs
in the formula, σsUniaxial compressive strength value of the fractured rock sample before freeze-thaw cycling;
σfthe uniaxial compressive strength value of the fractured rock sample after freeze-thaw cycling;
the rate of quality degradation
Comprises the following steps:
in the formula, V1The ultrasonic wave speed of the dried fractured rock sample is obtained;
V2the ultrasonic wave velocity of the fractured rock sample after freeze-thaw cycle;
the volume expansion ratio λ is:
λ＝(ρ1-ρ2)/ρ1
in the formula, ρ1The density of the dried fractured rock sample;
ρ2is the density of the fractured rock sample after the freeze-thaw cycle.
Further, the comprehensive index FTC for evaluating the freeze resistance of the fractured rock sample in the step S7 is as follows:
in the formula, a, b, c and d are respectively fracture micro-strain rate coefficient, strength loss rate coefficient, quality deterioration rate coefficient and volume expansion rate coefficient when determining comprehensive index for evaluating the freezing resistance of the fractured rock sample.
The invention has the beneficial effects that:
according to the test method for evaluating the freeze-thaw resistance of the fractured rock mass, fractures with different widths, lengths, inclination angles and groups of numbers can be manufactured by self-manufacturing the fractures in the aspect of the test method, so that the pertinence and the applicability of the test are improved; in the aspect of evaluation indexes, the comprehensiveness of the evaluation of the freeze-thaw resistance performance is reflected by establishing a multi-index fused comprehensive freeze-thaw resistance performance evaluation index, and a reference basis is provided for selecting rocks for engineering construction; in the aspect of freeze-thaw resistance, the freeze-thaw resistance of the rock mass under different concentrations and different types of karst solutions can be determined by the method.
Drawings
FIG. 1 is a flow chart of a test method for evaluating freeze-thaw resistance of a fractured rock mass provided by the invention.
Fig. 2 is a schematic diagram of an 1/4 bridge circuit provided by the present invention.
Fig. 3 is a schematic diagram illustrating the c-value decay comparison of saturated different solution sandstone freezing and thawing cycles in the embodiment of the present invention.
FIG. 4 is a graph showing the comparison of the c-value decay of freeze-thaw cycles of saturated granite solutions according to the present invention.
FIG. 5 is a schematic diagram showing the comparison of the c value decay of the phyllite freeze-thaw cycle saturated with different solutions in the embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in figure 1, the test method for evaluating the freeze-thaw resistance of the fractured rock mass comprises the following steps:
s1, selecting a rock mass to be tested, and cutting the rock mass into a plurality of fractured rock samples with standard compressive strength;
s2, putting all fractured rock samples into an oven to be dried to constant weight;
s3, pasting a strain gauge on the dried fractured rock sample, and connecting the strain gauge with the strain gauge through a test line;
s4, soaking the fractured rock sample in a saturated solution, and simulating a saturated fracture;
s5, placing the fractured rock sample with the saturated fractures into a refrigerator, simulating for a plurality of freeze-thaw cycles, and recording strain data in the process of the freeze-thaw cycles through a strain gauge;
s6, determining indexes of the fractured rock sample after different freeze-thaw cycle times according to the recorded strain data;
and S7, calculating a comprehensive index for evaluating the freeze-thaw resistance of the fractured rock mass according to the indexes of the fractured rock samples.
The step S1 is specifically:
selecting rock masses with the same properties, cutting out a plurality of standard rock samples by a water drilling method, and cutting out a seam on each rock sample to simulate the fracture in the rock mass so as to obtain a plurality of fractured rock samples.
Wherein the rock sample having a standard compressive strength has a size of
Is the diameter of the cylindrical sample, h1Is the height of the cylindrical rock sample; the length L of the cut crack is 10-50mm, and the width W is 1-3 mm.
In the step S2, the setting method of the oven parameters when the fractured rock sample is placed in the oven and dried to constant weight is as follows: the oven temperature was set at 105 ℃ and the drying time was set at 48 hours.
Wherein, for the index of confirming the fracture rock specimen in the follow-up step, need to measure following parameter after the fracture rock specimen dries: mass m of fractured rock sample1Density of fractured rock sample
And the ultrasonic wave velocity V of the fractured rock sample1。
The step S3 is specifically:
s31, wiping the surfaces of all fractured rock samples to remove stains, and polishing the fractured rock samples at the fracture positions by using abrasive paper to flatten the surfaces of the fractured rock samples;
s32, pasting a strain gauge in the middle of a crack rock sample with a flat surface, and coating a layer of silicon rubber on the surface of the pasted strain gauge;
the method for pasting the strain gauge specifically comprises the following steps: dripping a drop of 502 glue at the middle position of a crack at the top end of a cracked rock sample to be contacted with the strain gauge, uniformly coating the strain gauge, throwing off the redundant glue, immediately placing the strain gauge at the pasting position of the strain gauge, and after the strain gauge is pasted, checking whether the strain gauge is firmly pasted or not and solving the problems of short circuit and open circuit; and after the surface of the adhered strain gauge is coated with the silicon rubber, standing for 3-4 hours to completely solidify the strain gauge, wherein the purpose of coating the silicon rubber is to prevent the strain gauge from losing effectiveness when moisture touches the strain gauge.
S33, connecting one end of the test wire with the strain gauge, and connecting the other end of the test wire with the strain gauge according to a 1/4 bridging method to complete the pasting of the strain gauge and the connection of the strain gauge and the strain gauge;
the middle part of the test wire is fixed on the fractured rock sample through an insulating adhesive tape, each channel of the strain gauge is connected with a temperature compensation sheet, and vaseline is smeared on the exposed connecting wire.
The strain gauge used in the invention is DH3816, and meanwhile, the strain gauge is connected with a computer to form a full-intelligent itinerant data acquisition system, and strain values of cracks in the test process can be automatically, accurately, reliably and quickly acquired.
Wherein, the circuit principle of connecting the strain gauge and the strain gauge by the 1/4 bridging method is shown in figure 2,
the step S4 is specifically:
s41, sequentially soaking the 1/4 fractured rock sample, the 1/2 fractured rock sample and the 3/4 fractured rock sample in a saturated solution for 2 hours to exhaust air in the fractured rock samples;
s42, completely soaking the fractured rock sample with air exhausted in a saturated solution for 24 hours to saturate the fractured rock sample;
and S43, sealing the cracks in the fractured rock sample of the saturated solution by waterproof glue and filling water to simulate the saturated cracks.
The step S5 is specifically:
s51, correcting the sensitivity coefficient of the strain gauge connected with the strain gauge, and checking a connecting circuit of the test line;
wherein, the sensitivity coefficient of the strain gauge is corrected to 2.0000, and after detecting that the connecting line is error-free, the patrol key is cleared by pressing the 'total clear' combination key.
S52, placing the fractured rock sample into a refrigerator, simulating freeze-thaw cycles for a plurality of times by adjusting the temperature of the refrigerator, and recording strain data of the fractured rock sample in each freeze-thaw cycle through a strain gauge;
wherein the strain data is the residual strain of the fractured rock sample after each freeze-thaw cycle.
The method for simulating freeze-thaw cycling by adjusting the temperature of the refrigerator specifically comprises the following steps: turning on a refrigerator power supply, adjusting the temperature to-20 ℃, turning off the refrigerator power supply after 6 hours to naturally raise the temperature to 20 ℃ so as to complete one freeze-thaw cycle of the fractured rock sample in the refrigerator. While strain data was recorded during the cyclic freeze-thaw process, strain data was recorded 3 times per minute.
The indexes of the fractured rock sample in the step S6 include fracture microstrain rate epsilon, strength loss rate f and quality deterioration rate
And a volume expansion ratio λ;
wherein the fracture microstrain rate epsilon is as follows:
ε＝ε'/W
in which ε' is an accumulationResidual strain, and
wherein n is the number of freeze-thaw cycles; ε riThe residual strain of the fractured rock sample after the ith freeze-thaw cycle is shown;
w is the fracture width of the fractured rock sample;
the strength loss rate f is:
f＝(σs-σf)/σs
in the formula, σsUniaxial compressive strength value of the fractured rock sample before freeze-thaw cycling;
σfthe uniaxial compressive strength value of the fractured rock sample after freeze-thaw cycling;
wherein the uniaxial compressive strength value of the fractured rock sample is obtained by testing a rock rigidity testing machine with the model number of MTS 815;
the rate of quality degradation
Comprises the following steps:
in the formula, V1The ultrasonic wave speed of the dried fractured rock sample is obtained;
V2the ultrasonic wave velocity of the fractured rock sample after freeze-thaw cycle;
the ultrasonic wave speed of the fractured rock sample is obtained by testing an ultrasonic velocimeter, and after different times of freeze-thaw cycles, the ultrasonic wave speed is reduced after the rock is damaged, so that the quality degradation rate of the fractured rock sample can be reflected by measuring the ultrasonic wave speed;
the ultrasonic velocimeter in the invention is composed of four parts of a power supply, a transmitting system (a transmitter and a transmitting transducer), a receiving system (a receiver and a receiving transducer) and a display measuring system, and the like, and the longitudinal wave of the test frequency is 700 kHz.
The volume expansion ratio λ is:
λ＝(ρ1-ρ2)/ρ1
in the formula, ρ1The density of the dried fractured rock sample;
ρ2is the density of the fractured rock sample after the freeze-thaw cycle,
wherein m is2Is the quality of the fractured rock sample after freeze-thaw cycling,
is the diameter of fractured rock sample after freeze-thaw cycling, h2Is the height of the fractured rock sample after the freeze-thaw cycle.
After the fractured rock sample is subjected to freeze-thaw cycles for different times, the rock is damaged and then expands in volume, and the density is reduced, so that the expansion rate of the fractured rock sample can be reflected by measuring the density.
The comprehensive index FTC for evaluating the freeze resistance of the fractured rock sample in the step S7 is as follows:
in the formula, a, b, c and d are fracture micro-strain rate coefficient, strength loss rate coefficient, quality deterioration rate coefficient and volume expansion rate coefficient respectively when determining comprehensive index for evaluating the freezing resistance of the fractured rock sample, wherein a is 10-20, b is 50-60, c is 20-30 and d is 10-20.
In one embodiment of the invention, a comparative test for determining the freeze-thaw resistance of the corresponding fractured rock mass by soaking the fractured rock sample with different saturated solutions is provided:
in this example, 3 representative rocks, which are phyllite, sandstone and granite, were selected from the wenma highways in the tibet zone of sichuan. Selecting rock sample with small property difference as much as possible, drilling in situ to obtain medium-stroke rock mass, and drilling standard rock sample with size of
The rock samples were divided into two groups: each lithology of a group is divided into 9 samples, the 3 samples are respectively saturated with water, 23.1 percent of sodium chloride and 29.9 percent of calcium chloride solution, a seam with the length of 50mm and the width of 2mm is cut on each rock sample and is used as a fracture in a simulated rock body to observe the dependent variable under the freeze-thaw action; and dividing each 36 rock samples with lithology into three groups of saturated water, sodium chloride and calcium chloride solutions, performing freeze-thaw cycle, and performing triaxial strength test on the rock samples subjected to freeze-thaw cycle for 0, 15, 30 and 50 times by using a servo control rigidity testing machine.
Through rock triaxial compression test, can obtain rock stress-strain overall process curve: by applying a1Axial pressure being ordinate, σ3The confining pressure is an abscissa, the axial pressure and the confining pressure point of each test piece in a group when being damaged are drawn in a coordinate system, an optimal relation curve is made by a least square method, and the c, the m and the m of the rock are obtained by using the formula (1) and the formula (2),
The value is obtained.
Through the comparison of the c value attenuation of the shear strength parameters of the saturated rock sample and the saturated chlorine salt solution rock sample before and after freeze thawing, the strength parameter of the saturated chlorine salt solution rock sample is more slowly attenuated after freezing and thawing. After the saturated sodium chloride solution sandstone sample undergoes 50 freeze-thaw cycles, the c value is attenuated by 12.9%; after 50 times of freeze-thaw cycles, c value of the sandstone in the saturated calcium chloride solution is attenuated by 15.5%; and after 50 times of freeze-thaw cycles, the c value of the water-saturated sandstone is attenuated by 26.4%, the attenuation amplitude is 2.05 times of that of sodium chloride and is 1.71 times of that of calcium chloride (figure 3).
Sandstone rock sample in saturated sodium chloride solutionAfter 50 cycles of the freeze-thaw cycle,
the value did not decay, but increased by 0.25%; after 50 freeze-thaw cycles of the sandstone saturated with calcium chloride solution,
the value also increased by 4.1%; and the water-saturated sandstone is subjected to freeze-thaw cycling for 50 times
The value decayed by 3.0%.
Also, the chloride solution also plays a role in inhibiting deterioration during the freeze-thaw cycles of granite and phyllite: for granite, the intensity of the saturated sodium chloride solution after 50 freeze-thaw cycles is only 1/10 of the intensity of the saturated rock sample after 50 freeze-thaw cycles, and the intensity of the rock sample of the saturated calcium chloride solution after 50 freeze-thaw cycles is only 1/3 of the saturated rock sample (fig. 4); for phyllite, the intensity decay amplitude of the saturated sodium chloride solution after 50 freeze-thaw cycles is only 1/11 of the intensity of the saturated rock sample after 50 freeze-thaw cycles, and the intensity decay of the rock sample of the saturated calcium chloride solution after 50 freeze-thaw cycles is only 1/2 of the saturated rock sample (fig. 5).
The invention has the beneficial effects that:
according to the test method for evaluating the freeze-thaw resistance of the fractured rock mass, fractures with different widths, lengths, inclination angles and groups of numbers can be manufactured by self-manufacturing the fractures in the aspect of the test method, so that the pertinence and the applicability of the test are improved; in the aspect of evaluation indexes, the comprehensiveness of the evaluation of the freeze-thaw resistance performance is reflected by establishing a multi-index fused comprehensive freeze-thaw resistance performance evaluation index, and a reference basis is provided for selecting rocks for engineering construction; in the aspect of freeze-thaw resistance, the freeze-thaw resistance of the rock mass under different concentrations and different types of karst solutions can be determined by the method.
Claims (10)
1. A test method for evaluating freeze-thaw resistance of fractured rock mass is characterized by comprising the following steps:
s1, selecting a rock mass to be tested, and cutting the rock mass into a plurality of fractured rock samples;
s2, putting all fractured rock samples into an oven to be dried to constant weight;
s3, pasting a strain gauge on the dried fractured rock sample, and connecting the strain gauge with the strain gauge through a test line;
s4, soaking the fractured rock sample in a saturated solution, and simulating a saturated fracture;
s5, placing the fractured rock sample with the saturated fractures into a refrigerator, simulating for a plurality of freeze-thaw cycles, and recording strain data in the process of the freeze-thaw cycles through a strain gauge;
s6, determining indexes of the fractured rock sample after different freeze-thaw cycle times according to the recorded strain data;
and S7, calculating a comprehensive index for evaluating the freeze-thaw resistance of the fractured rock mass according to the indexes of the fractured rock samples.
2. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 1, wherein the step S1 is specifically as follows:
selecting rock masses with the same properties, cutting out a plurality of standard rock samples by a water drilling method, and cutting out a seam on each rock sample to simulate the fracture in the rock mass so as to obtain a plurality of fractured rock samples.
3. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 1, wherein in the step S2, the setting method of the oven parameters when the fractured rock sample is placed in the oven and dried to constant weight is as follows: the oven temperature was set at 105 ℃ and the drying time was set at 48 hours.
4. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 2, wherein the step S3 is specifically as follows:
s31, wiping the surfaces of all fractured rock samples to remove stains, and polishing the fractured rock samples at the fracture positions by using abrasive paper to flatten the surfaces of the fractured rock samples;
s32, pasting a strain gauge in the middle of a crack rock sample with a flat surface, and coating a layer of silicon rubber on the surface pasted with the strain gauge;
s33, connecting one end of the test wire with the strain gauge, and connecting the other end of the test wire with the strain gauge according to a 1/4 bridging method to complete the adhesion of the strain gauge and the connection of the strain gauge;
the middle part of the test wire is fixed on the fractured rock sample through an insulating adhesive tape, and each channel of the strain gauge is connected with a temperature compensation sheet.
5. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 1, wherein the step S4 is specifically as follows:
s41, sequentially soaking the 1/4 fractured rock sample, the 1/2 fractured rock sample and the 3/4 fractured rock sample in a saturated solution for 2 hours to exhaust air in the fractured rock samples;
s42, completely soaking the fractured rock sample with air exhausted in a saturated solution for 24 hours to saturate the fractured rock sample;
and S43, sealing the cracks in the fractured rock sample of the saturated solution by waterproof glue and filling water to simulate the saturated cracks.
6. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 1, wherein the step S5 is specifically as follows:
s51, correcting the sensitivity coefficient of the strain gauge connected with the strain gauge, and checking the connection line of the test line;
s52, placing the fractured rock sample into a refrigerator, simulating freeze-thaw cycles for a plurality of times by adjusting the temperature of the refrigerator, and recording strain data of the fractured rock sample in each freeze-thaw cycle through a strain gauge;
wherein the strain data is the residual strain of the fractured rock sample after each freeze-thaw cycle.
7. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 6, wherein the step S52 of simulating the freeze-thaw cycle by adjusting the temperature of the refrigerator specifically comprises the following steps:
turning on a refrigerator power supply, adjusting the temperature to-20 ℃, turning off the refrigerator power supply after 6 hours to naturally raise the temperature to 20 ℃ so as to complete one freeze-thaw cycle of the fractured rock sample in the refrigerator.
8. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 1, wherein the indexes of the fractured rock sample in the step S6 include fracture micro strain rate ε, strength loss rate f and quality deterioration rate
And a volume expansion ratio lambda.
9. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 8, wherein the fracture microstrain rate epsilon is as follows:
ε＝ε'/W
wherein ε' is the cumulative residual strain, an
Wherein n is the number of freeze-thaw cycles; ε riThe residual strain of the fractured rock sample after the ith freeze-thaw cycle is shown;
w is the fracture width of the fractured rock sample;
the strength loss rate f is:
f＝(σs-σf)/σs
in the formula, σsUniaxial compressive strength value of the fractured rock sample before freeze-thaw cycling;
σfthe uniaxial compressive strength value of the fractured rock sample after freeze-thaw cycling;
the rate of quality degradation
Comprises the following steps:
in the formula, V1The ultrasonic wave speed of the dried fractured rock sample is obtained;
V2the ultrasonic wave velocity of the fractured rock sample after freeze-thaw cycle;
the volume expansion ratio λ is:
λ＝(ρ1-ρ2)/ρ1
in the formula, ρ1The density of the dried fractured rock sample;
ρ2is the density of the fractured rock sample after the freeze-thaw cycle.
10. The test method for evaluating the freeze-thaw resistance of the fractured rock mass according to claim 8, wherein the comprehensive index FTC for evaluating the freeze resistance of the fractured rock sample in the step S7 is as follows:
in the formula, a, b, c and d are respectively fracture micro-strain rate coefficient, strength loss rate coefficient, quality deterioration rate coefficient and volume expansion rate coefficient when determining comprehensive index for evaluating the freezing resistance of the fractured rock sample.
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| CN111537702A (en) * | 2020-06-15 | 2020-08-14 | 成都理工大学 | Method for obtaining freeze-thaw single-crack imperial rock deformation failure mechanism |
| WO2021258833A1 (en) * | 2020-06-24 | 2021-12-30 | 山东科技大学 | Experimentation method for type i stress intensity factor test with frost heaving force periodic changes taken into consideration |
| CN113984807A (en) * | 2021-10-28 | 2022-01-28 | 中国科学院西北生态环境资源研究院 | Test method for rock fracture real-time expansion based on freeze thawing and fracturing |
| CN116935983A (en) * | 2023-02-25 | 2023-10-24 | 长安大学 | Prediction method for rock physical and mechanical property attenuation degree after freeze thawing |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8739634B2 (en) * | 2011-01-31 | 2014-06-03 | Construction Research & Technology Gmbh | Freeze thaw damage resistance testing for cementitious compositions |
| CN106568390A (en) * | 2016-10-31 | 2017-04-19 | 苏州热工研究院有限公司 | Concrete freeze-thaw expansion strain sensor |
| CN106918629A (en) * | 2017-03-02 | 2017-07-04 | 河海大学 | A kind of rock behavio(u)r test system and its damage of rock evolution method of testing |
| CN108645676A (en) * | 2018-05-25 | 2018-10-12 | 吉林建筑大学 | Seasonal frost region subgrade soils material damage methods of testing and evaluating based on ultrasonic technology |
-
2019
- 2019-10-29 CN CN201911034867.8A patent/CN110940693B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8739634B2 (en) * | 2011-01-31 | 2014-06-03 | Construction Research & Technology Gmbh | Freeze thaw damage resistance testing for cementitious compositions |
| CN106568390A (en) * | 2016-10-31 | 2017-04-19 | 苏州热工研究院有限公司 | Concrete freeze-thaw expansion strain sensor |
| CN106918629A (en) * | 2017-03-02 | 2017-07-04 | 河海大学 | A kind of rock behavio(u)r test system and its damage of rock evolution method of testing |
| CN108645676A (en) * | 2018-05-25 | 2018-10-12 | 吉林建筑大学 | Seasonal frost region subgrade soils material damage methods of testing and evaluating based on ultrasonic technology |
Non-Patent Citations (10)
| Title |
|---|
| JIAN-QIAO MU: "Degradation characteristics of shear strength of joints in three rock types due to cyclic freezing and thawing", 《COLD REGIONS SCIENCE AND TECHNOLOGY》 * |
| LIANG CHEN: "Experimental Investigation on Dynamic Fracture Mechanism and Energy Evolution of Saturated Yellow Sandstone under Different Freeze-Thaw Temperatures", 《ADVANCES IN CIVIL ENGINEERING》 * |
| PENG WANG: "A prediction model for the dynamic mechanical degradation of sedimentary rock after a long-term freeze-thaw weathering_ Considering the strain-rate effect", 《COLD REGIONS SCIENCE AND TECHNOLOGY》 * |
| 刘泉声: "裂隙岩体冻融损伤研究进展与思考", 《岩石力学与工程学报》 * |
| 张慧梅: "冻融岩石损伤劣化及力学特性试验研究", 《煤炭学报》 * |
| 裴向军: "干燥及饱水状态下裂隙岩石冻融特征研究", 《岩土力学》 * |
| 邹雪晴: "裂隙砂岩冻融循环变形特征初探", 《科学技术与工程》 * |
| 闻磊: "冻融循环作用下花岗斑岩和灰岩物理力学性质对比分析及应用研究", 《冰川冻土》 * |
| 阎锡东: "基于微裂隙变形与扩展的岩石冻融损伤本构模型研究", 《岩土力学》 * |
| 黄诗冰: "岩体冻融疲劳损伤模型与评价指标研究", 《岩石力学与工程学报》 * |
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| CN111537702A (en) * | 2020-06-15 | 2020-08-14 | 成都理工大学 | Method for obtaining freeze-thaw single-crack imperial rock deformation failure mechanism |
| WO2021258833A1 (en) * | 2020-06-24 | 2021-12-30 | 山东科技大学 | Experimentation method for type i stress intensity factor test with frost heaving force periodic changes taken into consideration |
| US11609195B2 (en) | 2020-06-24 | 2023-03-21 | Shandong University Of Science And Technology | Experimental method of type I stress intensity factor test considering periodic changes of frost-heave forces |
| CN113984807A (en) * | 2021-10-28 | 2022-01-28 | 中国科学院西北生态环境资源研究院 | Test method for rock fracture real-time expansion based on freeze thawing and fracturing |
| CN116935983A (en) * | 2023-02-25 | 2023-10-24 | 长安大学 | Prediction method for rock physical and mechanical property attenuation degree after freeze thawing |
| CN116935983B (en) * | 2023-02-25 | 2024-04-12 | 长安大学 | Prediction method for rock physical and mechanical property attenuation degree after freeze thawing |
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