阅读说明：本技术 一种快速测算石质文物过火温度的方法 (Method for rapidly measuring and calculating fire passing temperature of stone cultural relics ) 是由 张中俭 刘建彬 李黎 邵明申 陈卫昌 周怡杉 于 2020-12-11 设计创作，主要内容包括：本发明涉及一种快速测算石质文物过火温度的方法,包括：确定石质文物石材种类和采集地；获取相同的新鲜岩石样品；制备实验样品；对实验样品加热至不同的目标温度进行热处理,对每一级目标温度热处理后的实验样品进行细观参数测量；建立细观参数与温度之间的相关关系并汇总形成数据对应关系表；当实际火灾发生时,取样岩石小样品,测量岩石小样品的细观参数值,然后根据所建立的数据对应关系表反算取样位置可能经历的过火温度。本发明提供一种适用于火灾灾后的石质材料过火温度评价的方法,用于科学地评价火灾中不同部分受高温损伤的程度,解决现有的火灾灾后石质文物材料性质快速评价困难的问题,取样少,对文物损害小,应用广泛。(The invention relates to a method for rapidly measuring and calculating the fire passing temperature of stone cultural relics, which comprises the following steps: determining the types and the collection places of the stone cultural relics and the stones; obtaining the same fresh rock sample; preparing an experimental sample; heating the experimental sample to different target temperatures for heat treatment, and measuring microscopic parameters of the experimental sample subjected to heat treatment at each stage of target temperature; establishing a correlation between the microscopic parameters and the temperature and summarizing to form a data corresponding relation table; when an actual fire disaster occurs, sampling a small rock sample, measuring a microscopic parameter value of the small rock sample, and then reversely calculating the fire passing temperature possibly experienced by the sampling position according to the established data corresponding relation table. The invention provides a method for evaluating the fire passing temperature of a stone cultural relic material after fire disaster, which is used for scientifically evaluating the high-temperature damage degree of different parts in the fire disaster, solving the problem that the existing stone cultural relic material after the fire disaster is difficult to evaluate quickly, and has the advantages of less sampling, less damage to the cultural relic and wide application.)

1. A method for rapidly measuring and calculating the fire passing temperature of stone cultural relics is characterized by comprising the following steps:

step 10, determining the stone type and the collection place for building the stone cultural relics;

step 20, obtaining a fresh rock sample of the same kind as the stone cultural relic in the same collection place;

step 30, preparing an experimental sample by using the obtained fresh rock sample;

step 40, heating the experimental sample to different target temperatures in a grading manner for heat treatment;

step 50, performing mesoscopic parameter measurement on the experimental sample subjected to heat treatment at each stage of target temperature, establishing a correlation between the mesoscopic parameter and the temperature, and summarizing the stone type, the collection place and the correlation between the measurement data of the mesoscopic parameter and the temperature to form a data corresponding relation table;

and step 60, when an actual fire disaster occurs, sampling small rock samples at different positions in the fire passing area of the stone cultural relics, measuring the microscopic parameter values of the small rock samples by using the same method as the step 50, and then reversely calculating the fire passing temperature experienced by the sampling positions according to the established data corresponding relation table.

2. The method as claimed in claim 1, wherein in step 10, the type and collection place of the stone material are determined according to technical documents or construction records of the stone cultural relics; preferably, in the process of determining the stone subclasses used by the stone cultural relics, a method of combining historical literature records and petrological characteristics is adopted; the petrological characteristics comprise rock structure, color, components and contents of each component, and also comprise gap filler, cement and the like.

3. A method according to claim 1, characterized in that in step 20, each typical sub-class of rock is collected as a fresh rock sample for each different stratum in the pit of the collection site to match the rock material used for the stone relic correctly.

4. The method of claim 1, wherein in step 40, the target temperature for heating the test sample is above 1000 ℃; preferably, the target temperature of heating should be increased in equal steps; preferably, the target temperature of heating is room temperature, 200 ℃, 400 ℃, 600 ℃, 800 ℃, 1000 ℃; preferably, the rate of temperature rise and fall is generally not more than 10 ℃ per minute, and the temperature should be maintained for more than 2 hours after the target temperature is reached.

5. The method according to claim 1, characterized in that step 40 is followed by step 41 of analyzing the mineral composition of the test sample, in particular by:

comparing the mineral composition of the heat treated test sample with the mineral composition of the unheated sample;

judging whether the main composition minerals have mineral phase change or not according to the mineral composition results;

for the continuous use of the non-generated mineral phase change, the generated mineral phase change indicates that the mineral property is rapidly deteriorated and the mineral cannot be continuously used;

preferably, the method of analysis of the mineral composition employs a powder XRD method.

6. The method of claim 1, wherein in step 50, the measured microscopic parameters include particle size distribution and linear crack density; preferably, the particle size distribution and the linear crack density are determined using a photomicrograph taken; preferably, the polarizer is photographed in a reflection mode and under a single polarization using a polarization microscope; preferably, the thickness of the polaroid is 10 to 20 times of the diameter of the rock-making mineral crystal, and resin is injected for fixing before the polaroid is ground.

7. The method according to claim 6, characterized in that the measurement of the particle size distribution is in particular:

for polycrystalline rock with obvious grain boundary, such as granite, directly using a binary image or a gray image and then carrying out statistics;

for single crystal rocks such as marbles where grain boundaries are less pronounced, the following steps are used:

adjusting the brightness and contrast of the picture, and strengthening the grain boundary to make the grain boundary in the original image become obvious;

extracting a grain boundary grid;

converting the image into a gray image, and filling particles surrounded by particle boundaries with different colors;

counting the number of particles, the average particle diameter and the particle area of the filled color block particles;

preferably, the particle size distribution fitting result obtains a correlation formula between the scale parameter μ and the heating temperature T, wherein the correlation formula is as follows:

μ＝0.073T-89.712(R²＝0.971)

wherein R is²Is the goodness of fit.

8. The method according to claim 6, characterized in that the statistical step of the line crack density is embodied as:

establishing a new transparent layer on the photographed polarized light micrograph, and drawing cracks on the layer by using a curve with the width close to the width of the cracks in the photograph to obtain a crack network;

deriving a layer containing the crack network to obtain an image only containing the crack network;

calculating the area occupied by all cracks in the image, and dividing the area by the width of the crack to obtain the total length of the crack, wherein the dimension is [ L ];

dividing the total length of the crack by the total area of the image to obtain the linear crack density with the dimension [ L^-1]；

Preferably, the linear crack density ρ follows a linear relationship with the evolution of the heating temperature T, the linear relationship satisfying the following formula:

ρ＝2.149×10^-5T+0.00274(R²＝0.948)

wherein R is²Is the goodness of fit.

9. The method of claim 1, wherein in step 60, a small sample of rock is taken from the stone cultural relics in the fire passing area, and the rock types are analyzed to correspond to the types in the data correspondence table; and (4) inversely calculating the fire temperature according to the data corresponding relation of the corresponding rock types by analyzing the microscopic parameters of the small sample.

10. The method according to claim 1, wherein the small sample of sampled rock is a small sample of millimeter-sized stone cultural relics, in particular a small sample of stone cultural relics spalling caused by fire passing or a small sample of millimeter-sized rock drilled from the surface layer of the stone cultural relics in step 60.

Technical Field

The invention relates to the technical field of stone cultural relic fire passing temperature analysis, in particular to a method for quickly measuring and calculating the fire passing temperature of a stone cultural relic, which is used for quickly evaluating the fire passing temperature of the stone cultural relic after a fire disaster occurs.

Background

China is a cultural ancient country with civilization for thousands of years, and a large number of precious stone cultural relics are left in the thousands of years of historical long rivers. Since ancient times, fire has always been a great threat to the protection of cultural relics. Although the possibility of fire is greatly reduced by the aid of modern technology, the occurrence of fire is still unavoidable.

Since the fire is unavoidable, a scientific method is adopted for pre-research, and the damage degree of different parts of the stone cultural relic can be rapidly and accurately evaluated after the fire occurs, so that the rapid establishment of an emergency repair scheme to reduce the loss becomes an important subject. A common concern after a fire has occurred is the effect that the fire has on the stability of the rock structure or structure. The temperature of the fire in the rock and the engineering properties of the rock after the fire have occurred are first answered.

Certainly, the establishment of a fire monitoring system for stone cultural relics before a fire occurs is an effective method, but a large amount of expenditure is consumed; in fact, the probability of fire disaster of stone cultural relics is extremely low, most of the stone cultural relics are idle or even abandoned even if a fire disaster monitoring system is arranged, and the monitoring system is damaged by high-temperature burning of a fire disaster when the fire disaster really occurs. Therefore, a method for determining the rock fire temperature after a fire occurs is needed, and at present, no relevant research or patent is provided for determining the rock fire temperature after the fire occurs. In addition, the cultural relic attribute of the stone cultural relic causes the size of the sampled sample to be limited, namely only a small sample on the cultural relic body can be taken for test testing.

Therefore, the invention is needed to invent a method for quickly measuring the fire passing temperature of stone cultural relic building stones after fire disasters according to a small amount of sample tests, and provides reference for the establishment of cultural relic repair schemes.

Disclosure of Invention

The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention, and it is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

In view of the shortcomings of the prior art, the invention aims to provide a method for measuring the stone fire passing temperature after fire disaster based on the action of high temperature on certain rock material and the establishment of quantitative relationship between the microscopic scale and the temperature.

To achieve the above objects, the present invention is based on the two recognition that (1) the mineral composition and morphology, physical and mechanical properties, and high temperature resistance of the same kind of rocks at the same location are substantially the same; (2) the types of the building stones used by a certain stone cultural relic are usually one or a limited number, so that the fine research on the stone cultural relic material is feasible.

The technical scheme of the invention is as follows:

the invention provides a method for rapidly measuring and calculating the fire passing temperature of stone cultural relics, which comprises the following steps:

step 10, determining the stone type and the collection place for building the stone cultural relics;

step 20, obtaining a fresh rock sample of the same kind as the stone cultural relic in the same collection place;

step 30, preparing an experimental sample by using the obtained fresh rock sample;

step 40, heating the experimental sample to different target temperatures in a grading manner for heat treatment;

step 50, performing mesoscopic parameter measurement on the experimental sample subjected to heat treatment at each stage of target temperature, establishing a correlation between the mesoscopic parameter and the temperature, and summarizing the stone type, the collection place and the correlation between the measurement data of the mesoscopic parameter and the temperature to form a data corresponding relation table;

and step 60, when an actual fire disaster occurs, sampling small rock samples at different positions in the fire passing area of the stone cultural relics, measuring the microscopic parameter values of the small rock samples by using the same method as the step 50, and then reversely calculating the fire passing temperature experienced by the sampling positions according to the established data corresponding relation table.

As a preferred embodiment, the type and the collection place of the stone are determined according to the technical file or the construction record of the stone cultural relic; preferably, in the process of determining the stone subclasses used by the stone cultural relics, a method of combining historical literature records and petrological characteristics is adopted; the petrological characteristics comprise rock structure, color, components and contents of each component, and also comprise gap filler, cement and the like.

In a preferred embodiment, each typical sub-class of rock is collected as a fresh rock sample for each of the different strata in the pit of the collection site to properly match the rock material used for the stone relic in step 20.

As a preferred embodiment, in step 40, the target temperature for heating the experimental sample should reach above 1000 ℃; preferably, the target temperature of heating should be increased in equal steps; preferably, the target temperature of heating is room temperature, 200 ℃, 400 ℃, 600 ℃, 800 ℃, 1000 ℃; preferably, the rate of temperature rise and fall is generally not more than 10 ℃ per minute, and the temperature should be maintained for more than 2 hours after the target temperature is reached.

As a preferred embodiment, step 40 is followed by step 41 of analyzing the mineral composition of the test sample, specifically:

comparing the mineral composition of the heat treated test sample with the mineral composition of the unheated sample;

judging whether the main composition minerals have mineral phase change or not according to the mineral composition results;

for the continuous use of the non-generated mineral phase change, the generated mineral phase change indicates that the mineral property is rapidly deteriorated and the mineral cannot be continuously used;

preferably, the method of analysis of the mineral composition employs a powder XRD method.

As a preferred embodiment, in step 50, the measured microscopic parameters include particle size distribution and linear crack density; preferably, the particle size distribution and the linear crack density are determined using a photomicrograph taken; preferably, the polarizer is photographed in a reflection mode and under a single polarization using a polarization microscope; preferably, the thickness of the polaroid is 10 to 20 times of the diameter of the rock-making mineral crystal, and resin is injected for fixing before the polaroid is ground.

As a preferred embodiment, the measurement of the particle size distribution is in particular:

for polycrystalline rock with obvious grain boundary, such as granite, directly using a binary image or a gray image and then carrying out statistics;

for single crystal rocks such as marbles where grain boundaries are less pronounced, the following steps are used:

adjusting the brightness and contrast of the picture, and strengthening the grain boundary to make the grain boundary in the original image become obvious;

extracting a grain boundary grid;

converting the image into a gray image, and filling particles surrounded by particle boundaries with different colors;

counting the number of particles, the average particle diameter and the particle area of the filled color block particles;

preferably, the particle size distribution fitting result obtains a correlation formula between the scale parameter μ and the heating temperature T, wherein the correlation formula is as follows:

μ＝0.073T-89.712(R²＝0.971)

wherein R is²Is the goodness of fit.

As a preferred embodiment, the statistical steps of the linear crack density are specifically as follows:

establishing a new transparent layer on the photographed polarized light micrograph, and drawing cracks on the layer by using a curve with the width close to the width of the cracks in the photograph to obtain a crack network;

deriving a layer containing the crack network to obtain an image only containing the crack network;

calculating the area occupied by all cracks in the image, and dividing the area by the width of the crack to obtain the total length of the crack, wherein the dimension is [ L ];

dividing the total length of the crack by the total area of the image to obtain the linear crack density with the dimension [ L^-1]；

Preferably, the linear crack density ρ follows a linear relationship with the evolution of the heating temperature T, the linear relationship satisfying the following formula:

ρ＝2.149×10^-5T+0.00274(R²＝0.948)

wherein R is²Is the goodness of fit.

As a preferred embodiment, in step 60, a small sample of rock is taken from the stone relic in the fire passing area, and the rock type is analyzed to correspond to the type in the data correspondence table; and (4) inversely calculating the fire temperature according to the data corresponding relation of the corresponding rock types by analyzing the microscopic parameters of the small sample.

In a preferred embodiment, in step 60, the sampled small rock sample is a small millimeter-sized small stone cultural relic sample, specifically, a small sample obtained by peeling off the stone cultural relic caused by fire passing or a small millimeter-sized small rock sample drilled from the surface layer of the stone cultural relic.

Compared with the prior art, the invention has the beneficial effects that: according to the action of high temperature on certain rock materials and the relationship between the quantified microcosmic and temperature, the invention can scientifically and rapidly measure the fire passing temperature of different parts of stone cultural relics after a fire happens by a large number of experiments and analyses in advance and establishing a data corresponding relation table, thereby providing support for the scheme establishment in the repairing and rebuilding processes. The method is quick in evaluation and wide in application. Specifically, the present invention has at least the following practical effects:

(1) the fire disaster early warning system can be used for researching microscopic parameters, temperature and related relations of the stone cultural relics and the same stone before a fire disaster happens, and can quickly judge the fire passing temperature according to the research result after the fire disaster happens;

(2) the measuring method is based on a small stone cultural relic sample, only a small amount of samples need to be taken out of the stone cultural relic, and the damage to the cultural relic is small;

(3) according to the method, the fire passing temperature of each part in the fire passing range of the stone cultural relics can be obtained through back-stepping according to the microscopic parameters;

(4) the method has small sampling volume, avoids the problem that the difference of samples with different over-fire temperatures is included in the error when a large sample is taken, and has more accurate test result.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the functions and purposes of the present invention, shall fall within the scope covered by the technical contents disclosed in the present invention.

FIG. 1 is a flow chart of a method for rapidly calculating a fire passing temperature of a stone cultural relic according to one embodiment of the invention;

FIG. 2 is a schematic diagram of the application positions of Qingbai stone and Hanbaiyu in the stone cultural relics in Beijing Temple of heaven according to one embodiment of the present invention;

FIG. 3 is a polarization micrograph of a sample after heat treatment at different temperatures according to one embodiment of the present invention, wherein panels a, b, c, d are samples after treatment at 25 deg.C, 200 deg.C, 400 deg.C and 600 deg.C, respectively;

FIG. 4 is a schematic diagram of a method for segmenting particles according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of filling crystalline grain color blocks in the grain segmentation method according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of microcrack grid extraction according to one embodiment of the invention;

FIG. 7 is a graph illustrating particle size distribution curves of samples after different temperature treatments according to one embodiment of the present invention;

FIG. 8a is a graph of dimensional parameters versus temperature for one embodiment of the present invention;

FIG. 8b is a graph of linear crack density versus temperature for one embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the embodiments of the present invention are described in further detail below with reference to the embodiments and the accompanying drawings. The exemplary embodiments and descriptions of the present invention are provided to explain the present invention, but not to limit the present invention.

It is to be understood that the terms "comprises/comprising," "consisting of … …," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a product, apparatus, process, or method that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such product, apparatus, process, or method if desired. Without further limitation, an element defined by the phrases "comprising/including … …," "consisting of … …," or "comprising" does not exclude the presence of other like elements in a product, device, process, or method that comprises the element.

It will be further understood that the terms "upper," "lower," "front," "rear," "left," "right," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present invention and to simplify description, and do not indicate or imply that the referenced device, component, or structure must have a particular orientation, be constructed in a particular orientation, or be operated in a particular manner, and should not be construed as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Rock material is usually formed mainly of one or several minerals after a certain geological action. The same kind of stone material usually has consistent mineral composition, and the rock formation process experiences the same geological history, so the rock physical mechanical property is relatively uniform, and the property change degree after the high temperature effect is also close.

The microscopic characteristics of rock materials change after being subjected to high temperature, and the change is generally divided into two stages: (1) when the maximum temperature of the rock material does not exceed the critical temperature of the main composition minerals of the rock, the change of the microscopic properties is within the physical change range, such as the bond failure between particles, the local breakage of the particles, the generation and the expansion of the micro cracks between crystals and the micro cracks in the crystals, which are caused by the anisotropic expansion and contraction of the mineral crystal particles; (2) when the maximum temperature of the rock material exceeds the critical temperature of the main composition minerals of the rock, the change of the microscopic property can generate chemical changes besides the physical change (1), such as the decomposition and recrystallization of mineral crystals, and the process causes the drastic change of the mechanical property of the mineral crystals; meanwhile, the products in the chemical change process can also increase the degree of physical change, such as the high-pressure gas escape process generated by mineral decomposition further promotes the generation and the expansion of microcracks. There are differences in the nature of the crystal grains, the variation in size and the number of microcracks at different temperatures. Selecting proper mesoscopic parameters to represent the change of the mesoscopic properties and establishing the relationship between the mesoscopic parameters and the temperature provides a new method for evaluating the temperature of the fire based on the mesoscopic parameters.

Based on the principle, as shown in fig. 1, the invention provides a method for rapidly measuring and calculating the fire passing temperature of stone cultural relics, which comprises the following steps: determining the stone type and the collection place for building the stone cultural relics; obtaining a fresh rock sample of the same kind as the stone cultural relic in the same collection place; preparing an experimental sample by using the obtained fresh rock sample; heating the experimental sample to different target temperatures for heat treatment, and measuring microscopic parameters of the experimental sample subjected to heat treatment at each stage of target temperature; establishing a correlation between the temperature and the microscopic parameters, and summarizing the correlation to form a data corresponding relation table; when an actual fire disaster occurs, sampling small rock samples at different positions in a fire passing area of the stone cultural relic, measuring the microscopic parameter values of the small rock samples by using the same method as before, and then reversely calculating the fire passing temperature possibly experienced by the sampling positions according to the data corresponding relation table established before. The method is suitable for quickly evaluating the fire passing temperature of the stone cultural relics after the fire disaster, and the fire passing temperature can be quickly measured and evaluated by pre-establishing a data corresponding relation table and microscopic parameters of small samples of the stone cultural relics after the fire disaster, so that the problem that the damage degree of the stone cultural relics after the fire disaster is difficult to evaluate is solved, and a reference basis is provided for formulating an emergency repair scheme after the fire disaster. The method is based on a small stone cultural relic sample, has small sampling volume, small damage to the cultural relic and wide application.

The technical solution of the present invention is specifically explained below with reference to the accompanying drawings.

The invention discloses a method for rapidly measuring and calculating the fire passing temperature of stone cultural relics through an embodiment. In this embodiment, a marbles cultural relic in beijing area is adopted, and the process is performed according to the following steps, taking a Temple of heaven:

step 10, determining the stone type and the collection place for building the stone cultural relics;

in the step, the type and the collection place of the stone are determined according to the technical file or the construction record of the stone cultural relic; preferably, in the process of determining the stone subclasses used by the stone cultural relics, a method of combining historical literature records and petrological characteristics is adopted; the rock characteristics comprise rock structure, color, components and contents of the components, and also comprise characteristics of gap filler, cement and the like.

In this example, according to the book "records in county of Liang shan county" by maqing, 1928, the stone material used in Beijing stone cultural relics is mainly marble in the great nest town of Liang shan of southwest Beijing. The research of Gaolinzhi et al (2010) finds that the stratum of the Beijing marble rock belongs to the carbonate rock stratum of precambrian Miyashan of Ji county.

According to the field investigation and mineral analysis of the heaven-altar stone cultural relics, the Beijing marble used by the stone cultural relics is mainly two subclasses, the subclass of bluish white stone is generally used as a bearing component of a building, and the subclass of white marble is used as an engraving and decorating component (as shown in figure 2).

Step 20, obtaining a fresh rock sample of the same kind as the stone cultural relic in the same collection place;

in the step, various typical subclasses of rock are collected from different strata in a collecting pit of a collecting place to serve as fresh rock samples so as to correctly match rock materials used by the stone cultural relics.

For the purpose of clearly describing the method described in this patent, the white marble material used for the carved and decorated members is taken as an example in this embodiment, and the same white marble material as that used for the stone cultural relics is collected from the great stone pit of Beijing mountain, and is explained in the subsequent steps.

In this stepIn order to minimize the error between different experimental samples, the samples used in the subsequent steps are taken from a whole block with approximate dimensions of 300X 400X 150mm³White marble of Han dynasty. The research method and steps of the Qingbaishi are the same as those of the Hanbaiyu, and repeated description is not given.

Step 30, preparing an experimental sample by using the obtained fresh rock sample;

samples (table 1) were prepared for various experimental purposes and were placed in an air-conditioned room for one week at a room temperature of 25 ℃ and a relative humidity of 35%. And then dried in an oven at 65 ℃ for 48 hours. After drying, the samples were packed in plastic sealed bags and stored sealed prior to the experiment.

TABLE 1 parameters of samples selected for different experimental purposes

Step 40, heating the experimental sample to different target temperatures in a grading manner for heat treatment;

in this step, the sample is heated to a high temperature of various degrees and cooled, and the temperature treatment is completed in a programmable heating furnace. The maximum temperature of the furnace was 1200 ℃. The samples were heated to 25 deg.C, 200 deg.C, 400 deg.C, 600 deg.C, 800 deg.C and 1000 deg.C, respectively. Accordingly, these samples heated to different temperatures are denoted as M25, M200, M400, M600, M800, and M1000. Each set of samples was heated to the desired temperature at a1 deg.C/min warming rate and held for 5 hours to reach the maximum temperature for all portions of the samples. Then, cooling the sample to 200 ℃ according to the cooling rate of 1 ℃/min; then the power supply of the heating furnace is closed, the furnace door is kept closed for 12 hours, and then the sample is taken out. The reason for this is that the cooling rate of the heating furnace is lower than 1 ℃/min when the temperature is lower than 200 ℃, so that the cooling rate can only be lower than 1 ℃/min in the stage of cooling from 200 ℃ to room temperature. The samples after removal were re-packed in sealed bags to avoid absorbing moisture from the air.

Step 41 is provided after this step, and the mineral composition of the experimental sample is analyzed, specifically: the mineral composition of the cube samples M25, M200, M400, M600, M800 and M1000 was measured and compared to the mineral composition of the heat treated samples and the unheated samples. This example uses powder X-ray diffraction (XRD) to perform mineral composition testing of samples using an AD/max 2400X-ray diffractometer.

In this step, the results of mineral composition testing are shown in table 2. According to the mineral composition results, the mineral compositions in the M800 and M1000 samples are subjected to mineral phase transition, the main mineral composition dolomite of the samples is decomposed to form lime and periclase, and the mineral properties after the high-temperature treatment at 800 ℃ and 1000 ℃ are rapidly deteriorated and the samples cannot be used continuously. The samples (M25 to M600) which did not undergo a phase change were then analyzed according to the subsequent steps.

TABLE 2 mineral composition of marbles samples after different high temperature treatments

Step 50, performing microscopic parameter measurement on the experimental sample subjected to heat treatment at each stage of target temperature:

in this step, the microscopic parameters include particle size distribution and linear crack density.

In this step, the polarizing microscopic observation and microscopic parameter analysis are performed on the polarizer sample after each stage of target temperature heat treatment, and the polarizing microscopic observation method comprises the following steps: after the heat treatment, the wafer sample was sliced, soaked in resin, and then ground into a polarizer. In order to reduce the damage to the sample caused by the disturbance generated during the grinding of the sample, the thickness of the polarizer was 1mm instead of 30 μm, which is conventionally used. Observing and photographing by adopting an Axio Scope A1 microscope of Karl Zeiss in a reflection mode and under a single-polarization condition; the polarization micrographs were taken by a built-in camera and transmitted to a computer. Polarization micrographs of M25 through M600 are shown in FIG. 3.

In this step, three polarization micrographs of the same size and magnification of the temperature-treated samples of each of M25, M200, M400, and M600 were analyzed; the particles in the photographs were extracted and analyzed to study their distribution characteristics, temperature dependence, and their relationship to temperature.

For the particle size distribution statistics, for the rocks with obvious particle boundaries, such as polycrystalline rocks like granite, the statistics can be performed by directly using a binary image or a gray image, and for the rocks with less obvious particle boundaries, such as single crystal rocks like marble, the crystal particles are generally divided and counted by the following steps: adjusting gray brightness, extracting grain boundaries, filling different color blocks with adjacent grains for distinguishing, and counting the number and size distribution of the color blocks.

In this step, the particle size analysis step is as follows: as shown in fig. 3, the contrast between grains and grain boundaries in the photograph taken is relatively weak. Conventional methods, such as contrast and brightness adjustment, and segmentation based on gray scale or RGB after conversion into a gray scale image, do not correctly segment the particles. In order to ensure the accuracy of image processing, the image is segmented by combining boundary extraction, color block filling particles and color block size statistics. The statistical method of the particle size is as follows: firstly, brightness and contrast are adjusted to strengthen the grain boundary, so that the grain boundary in the original image becomes obvious; then extracting a grain boundary grid (fig. 4); then converting the image into a gray scale image, and filling particles surrounded by particle boundaries with different colors (figure 5); finally, the number of particles, the average particle diameter and the particle area of the filled color block particles were counted.

In terms of linear crack density, linear crack density is defined as the total crack length divided by the total area of the image to give a linear crack density in the dimension [ L [ ]^-1]The total area of the image, i.e. the length times the width of the image.

In this step, the linear crack density analysis step is as follows: firstly, establishing a new image layer above a polarization micrograph, drawing cracks on the image layer by using a curve with the width close to that of the cracks in the polarization micrograph to obtain a crack network, and then deriving the image layer containing the crack network to obtain an image only containing the crack network (figure 6); then, the area occupied by all cracks in the image is calculated, and the total length of the crack is equal to the area occupied by all cracks divided by the width of the crack, and the dimension is [ L ]. It is to be noted that, in calculating the crack length by this method, the width of the curve shown in fig. 6 should be determined according to the scale of the polarization micrograph and the width of the curve for tracing the crack to ensure the accuracy of the calculation. In the present embodiment, the unit of the polarization micrograph is micrometers, and the width of the curve in the crack map is set to 6.7 micrometers in calculating the area according to the size and scale of the polarization micrograph.

In this step, a correlation between the microscopic parameter and the temperature is further established:

figure 7 shows the mineral particle size distribution of a heated sample at 25 ℃, 200 ℃, 400 ℃ and 600 ℃ subject to an improved rayleigh distribution multiplied by an amplification factor as shown in equation 1:

where a and μ are the magnification factor and scale parameter, respectively.

The fitting results are shown in table 3.

Table 3 improved rayleigh distribution fitting results

Sample (I)	Dimension parameter (mu)	Amplification factor (a)	R2
				M25	-90.2994	30308.58874	0.85452
M200	-72.16584	25869.09902	0.62062
				M400	-59.75576	45585.79832	0.83705
M600	-47.59334	46910.18893	0.84130

As shown in fig. 8a, it can be found from the fitting result that there is a strong correlation between the scale parameter μ and the heating temperature T, and the correlation satisfies the following formula 2:

μ＝0.073T-89.712(R²＝0.971) (2)

as shown in fig. 8b, the linear crack density ρ of the sample follows a linear relationship with the evolution of the heating temperature T, the linear relationship satisfying the following formula 3:

ρ＝2.149×10^-5T+0.00274(R²＝0.948) (3)

the data tested in the above experiment, and the correlation between the temperature and the microscopic parameters are summarized to form a data corresponding relation table.

And step 60, when an actual fire disaster occurs, sampling small rock samples at different positions in the fire passing area of the stone cultural relics, measuring the microscopic parameter values of the small rock samples by using the same method as the step 50, and then reversely calculating the fire passing temperature experienced by the sampling positions according to the data corresponding relation table established in the step 50.

Specifically, the particle size distribution and the linear crack density are measured, then the scale parameter is obtained through the particle size distribution and the linear crack density, and the corresponding temperature is obtained through the scale parameter.

From the above, since the particle size distribution (through the scale parameter) and the linear crack density are strongly correlated with the temperature change, the temperature value can be obtained by selecting one parameter theoretically, in practice, the two parameters are preferably measured, and the two parameters are selected to have comparability, so that the measurement result is further verified.

In the step, analyzing the rock types of the small rock samples sampled in the fire passing area so as to correspond to the types in the data corresponding relation table; and (4) inversely calculating the fire temperature according to the data corresponding relation of the corresponding types by analyzing the microscopic parameters of the small sample.

In this step, the sample rock small sample is specifically for boring the millimeter level rock small sample to the stone historical relic small sample is millimeter level stone historical relic small sample, can be the small sample that the stone historical relic that gets to cross fire and lead to peeled off, can avoid the secondary destruction to the historical relic like this to the at utmost, if there is not the small sample that suitable stone historical relic peeled off on the scene, also can bore from the stone historical relic top layer and get millimeter level rock small sample.

It should be noted that, since the method described in this embodiment is a pre-research method, it is impossible to damage the stone cultural relics in the example research, and therefore, the step of sampling the fire passing area in the content described in step 60 in this embodiment is not specifically performed. According to the principles that the physical and mechanical properties of building parts made of the same rock are close to each other and the mesoscopic properties of the rock are influenced by the temperature, and the relation between the mesoscopic parameters and the temperature of the sample obtained by the actual experiment in the embodiment, the rationality of the method can be self-proved.

Thus, it should be understood by those skilled in the art that while exemplary embodiments of the present invention have been illustrated and described in detail herein, many other variations and modifications can be made, which are consistent with the principles of the invention, from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.