CN112415092B - Method for detecting internal damage of historic building wood member - Google Patents

Method for detecting internal damage of historic building wood member Download PDF

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CN112415092B
CN112415092B CN202011201592.5A CN202011201592A CN112415092B CN 112415092 B CN112415092 B CN 112415092B CN 202011201592 A CN202011201592 A CN 202011201592A CN 112415092 B CN112415092 B CN 112415092B
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CN112415092A (en
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郑建国
王龙
钱春宇
李俊连
张凯
王伟
李欢
李嘉毅
曹杰
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China Jikan Research Institute Of Engineering Investigations And Design co ltd
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/07—Analysing solids by measuring propagation velocity or propagation time of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
    • G01N29/04—Analysing solids
    • G01N29/11—Analysing solids by measuring attenuation of acoustic waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
    • G01N33/46—Wood
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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Abstract

The invention discloses a method for detecting internal damage of an ancient building wood member, which screens the internal damage information of the ancient building wood member through a single-path stress wave detector and a micro-drilling resistance instrument, and considers the influences of different member positions and section surface forms. The detection method comprises the following steps: firstly, structural information is investigated and researched to provide basic data for detecting internal damage of a wood member; secondly, comprehensively surveying, and preliminarily determining components which are possibly damaged; thirdly, determining a key rechecking area, and reducing the workload and the working time of field detection; and fourthly, detecting the internal damage of the wood component, acquiring the internal damage type of the wood component, accurately positioning a damage boundary, and outlining a three-dimensional distribution map of the internal damage. The method provided by the invention has the advantages of simple steps and simplicity in operation, can quickly and effectively screen the internal damage and the size of the timber component of the historic building, and provides theoretical basis and technical support for subsequent safety assessment, maintenance and repair of the timber structure of the historic building.

Description

Method for detecting internal damage of historic building wood member
Technical Field
The invention belongs to the technical field of nondestructive testing of timber structures of ancient buildings, and particularly relates to a method for detecting internal damage of timber components of ancient buildings.
Background
The ancient building in China is a building system mainly of a wood structure, and main bearing components of the ancient building, such as columns, purlins and purlins, are all made of wood. The wood is a biological material, and is easily damaged by bacteria, insects, physical and chemical factors and the like in a long-term use process, so that the wood components are damaged by cracking, mildew, worm damage, decay and the like. In many cases, wood damage starts from the interior of the wood, but the traditional detection methods such as visual observation and knocking pressing cannot find out the damage condition in the component. This situation may cause the internal tiny damage of the ancient building timber component to continuously expand all the year round, miss the best protection and repair time of the timber component, even threaten the whole structure, cause collapse damage, and cause irreparable loss. At the moment, by using convenient and nondestructive detection equipment, the health and safety conditions of the wooden components are predicted under the condition of not damaging the original form and structure of the ancient building, and the accurate acquisition of the internal damage information of the wooden components is very necessary.
In China, single-path stress wave detection, ultrasonic detection, micro-drilling resistance detection, multi-path stress wave detection and the like are gradually applied to ancient building detection. However, in the field detection operation of the historic building timber structure, the detection conditions are often complex, such as the shape and the position of the member, and the like, so that the suitable detection equipment can be competent for corresponding detection tasks in a complex and harsh field environment, and the corresponding working precision and stability can be maintained. In addition, the detection information of the single-path stress wave detection technology is single, the position of the internal damage can be estimated only through the wave velocity, and the size of the damage cannot be judged; the micro-drilling resistance meter has the defects that only single-path identification can be realized, and the overall damage condition of the cross section cannot be acquired; the nonmetal ultrasonic detector generally needs a coupling agent and is not suitable for detecting components with roughness or large surface radian; although the multipath stress wave detector has the characteristics of visualization and quantification, the degree of the multipath stress wave detector is greatly different from the real damage degree, and information such as the shape, the boundary position and the like of the damage cannot be accurately positioned.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a method for detecting internal damage of an ancient building wood member, which fully considers the shape and the position of the member, reasonably selects detection equipment in combination with field operation conditions, controls the detection error within an acceptable range and realizes more comprehensive and specific evaluation of the internal damage of the main bearing wood member.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method for detecting internal damage of an ancient building wood member comprises the following steps:
the method comprises the following steps of firstly, determining the arrangement of a structural system and a bearing component of the historic building timber structure to be detected, retesting the outline structure size of a main component in the historic building timber structure, and providing basic data for detecting the internal damage of the timber component;
step two, generally surveying all accessible wood components of the historic building wood structure through observation and knocking, recording the material condition of the surface of the wood component, and preliminarily determining the components which are possibly damaged internally;
step three, determining key re-inspection areas of the problematic wood members and the main bearing members in the comprehensive detection in the step two, wherein the main bearing members comprise wood columns and beam balms;
and step four, carrying out nondestructive detection on the detection area in the step three by adopting nondestructive detection equipment, obtaining the distribution rule of the internal damage of the wood member and the quantitative boundary characteristics, and outlining the stereoscopic distribution map of the internal damage.
As a further improvement of the invention, the step one, wherein the common damage inside the wood member comprises: decay or worm damage, fissures, and cavities.
As a further improvement of the present invention, the recording of the material condition of the wood member in the second step includes: knocking sound, whether water stain exists, whether wood chip exists, whether concave surface exists and fruit body.
As a further improvement of the invention, the number of the main bearing members in the step three to be detected is sampled.
As a further improvement of the present invention, the key reinspection areas of the main bearing members in the third step are: the wood columns are concentrated at the root, and the beam purlin is concentrated at the midspan and the beam part node.
As a further improvement of the present invention, in the fourth step, there are differences in the detection devices selected for the members at different positions: the method comprises the following steps that a stress wave detector and a micro-drilling resistance instrument are adopted for a wood column and a beam purlin with the periphery completely exposed outside; the part of the wooden column which is wrapped by the wall or shielded only adopts a micro-drilling resistance meter.
As a further improvement of the invention, the stress wave detector is used for detecting the internal damage of the member, the internal damage condition of the wood member is determined according to the attenuation rate of the propagation velocity of the stress wave, and the transverse propagation velocity v of the stress wave of the healthy material0The relationship with the distance l between the sensors corresponds to the following equation:
Figure BDA0002755349510000031
in the formula, v0The unit is the transverse propagation speed of the stress wave in the healthy material and is m/s; l is the distance between two sensors of the stress wave detector, and the unit is m; t is the travel time in s, which is the average of three consecutive determinations of travel time, where the first tap travel time reading is invalid and is calculated from the second.
As a further improvement of the invention, the internal damage of the member is detected by using a micro-drilling resistance meter, the internal damage condition of the wood member is determined according to the resistance attenuation rate, and the resistance value of the healthy material is the average value of the measured values of the real wood part of the flawless wood member. Generally, a drill of the micro-drilling resistance instrument can drill into a defect-free wood member by at least 20mm, the first 5mm is an invalid value, and the average value of the resistance at the drilling depth of 5-15 mm is taken as the resistance value of the healthy material.
Compared with the prior art, the invention has the beneficial effects that:
1. based on the diversity and complexity of structural members, the restriction of position factors of the members on detection equipment is considered, different technical means are adopted for different detection parts, and the method has clear pertinence.
2. The internal damage detection effectively combines two detection means, exerts the advantages of the two detection means, eliminates disadvantages through complementation, not only can ensure the accuracy of damage type detection through mutual verification and avoid misjudgment and missing judgment, but also can realize the accurate positioning of the damage boundary and effectively ensure the accuracy of the basic data of historic building protection.
3. The detection equipment adopted by the invention hardly damages the structure, meets the basic requirement that the original appearance of the historic building is not damaged in the detection, is simple and convenient, has strong operability and is suitable for the complex field detection of the historic building.
In conclusion, the method has the advantages of reasonable design, concise steps and strong operability, can effectively solve the problem of internal damage detection of the wooden components of the ancient buildings, avoids misjudgment and missed judgment, effectively ensures the accuracy of the basic data of the ancient building protection, and is convenient to popularize and use in the engineering practice process of ancient building repair and maintenance.
Drawings
FIG. 1 is a flow chart of an embodiment of a method for detecting internal damage of an ancient building wood member.
FIG. 2 is a diagram of nondestructive testing area of the wooden pillar.
FIG. 3 is a diagram of a nondestructive testing area of a beam column.
Fig. 4 is a schematic diagram of a stress wave detection path with a circular cross section.
Fig. 5 is a schematic diagram of a stress wave detection path with a square section.
FIG. 6 is a schematic diagram of a round section damaged micro-drilling resistance needle insertion path.
FIG. 7 is a schematic diagram of a square cross-section damaged micro-drilling resistance needle insertion path.
FIG. 8 is a schematic view of the shielded wood pillar cross-section micro-drilling resistance needle insertion path.
Detailed Description
The features of the present invention and other related features are described in further detail below in conjunction with the appended drawings to facilitate an understanding of those skilled in the art.
The method for detecting the internal damage of the ancient building wood member screens the internal damage information of the ancient building wood member through the single-path stress wave detector and the micro-drill resistance meter, considers the influences of different member positions and section surface forms, has simple and clear steps and simple operation, can quickly and effectively screen the internal damage and the size of the ancient building wood member, and provides theoretical basis and technical support for subsequent safety assessment, maintenance and repair of the ancient building wood structure.
The equipment adopted by the invention comprises: stress wave detector and little brill resistance appearance. The stress wave detector is used for predicting the position and the type of damage of the internal part of the component; and the micro-drilling resistance meter is used for determining the internal damage boundary of the component and verifying the type of the damage.
As shown in fig. 1, the present invention mainly comprises the following steps:
step one, structural information investigation: confirm the structural system and the bearing member's of the ancient building timber structure that awaits measuring arrangement, carry out retest to the profile structure size of main component wherein, carry out preliminary investigation analysis to the inside common damage type of timber component, formation reason and distribution rule, for the inside damage detection of timber component provides basic data, wherein the inside common damage of timber component includes: decay or worm damage, fissures, and cavities.
Step two, comprehensive general investigation: the general survey is carried out to all accessible timber compoments of ancient building timber structure through observation and strike, records the material condition on timber compoment surface, includes: knocking sound, whether water stain exists, whether wood chip exists, whether concave surface exists or not, sporocarp and the like, and preliminarily determining a member which is possibly damaged; the types of damage that may exist are preliminarily judged by the examination phenomenon of table 1.
TABLE 1 evidence for determination of examination
Visual inspection Knocking sound Surface water stain Surface wood chip Surface depression Surface fruiting body
Presence condition Air blunt Exist of Exist of Exist of Exist of
Type of damage Decay, cavities or cracks Decay Is eaten by worms Decay Decay
Step three, determining a key rechecking area of the wood member: and (3) key re-inspection areas of the problematic wood members and the main bearing members such as the wood columns, the beam beams and the like in the comprehensive detection in the second step are respectively determined, the workload and the working time of field detection are reduced, wherein the number of the main bearing members can be detected in a sampling mode, and the detection areas of the main bearing members are as follows: the wood columns are concentrated at the root, and the beam purlin is concentrated at the midspan and the beam part node.
It should be noted that after the step two is performed with the comprehensive inspection, the number of the normal ancient building wood members is still relatively large, and the total inspection cannot be performed, and the wood members can be subjected to sampling inspection with reference to table 2.
TABLE 2 ancient building Wood component detection minimum sampling number
Figure BDA0002755349510000051
The detection and layout principle of the internal damaged cross section of the wood column specifically comprises the following steps: as shown in FIG. 2, the wooden pillar 1 is located on the pillar base 2, the cross section of the wooden pillar 1 at 0.2m upward from the pillar bottom is the lower boundary of the wooden pillar detection area 3, and the cross section detection is performed every 0.4m from the cross section of the pillar bottom at 0.2m upward, and the detection height range is not less than the larger value of 1/3 and 1.0m of the pillar height of the layer. If obvious internal damage is found in a certain cross section, the cross section is detected by encryption, and secondary scanning can be carried out on the cross section at the upper and lower 0.2m positions of the cross section with the problem.
The detection and layout principle of the internal damaged cross section of the beam purlin is as follows: as shown in fig. 3, at an end node of a beam purlin 4, a cross section of a column purlin boundary at a position of 0.1m along the direction of the purlin is a boundary of the beginning of a purlin end detection area 5, cross section detection is performed at intervals of 0.2m from a column purlin interface along the cross section of 0.1m along the direction of the purlin, and the detection length range is not less than the larger value of 1/6 and 0.5m of the length of the beam purlin; the middle part of the beam purlin 4 is a midspan detection area 6, in the midspan detection area 6, cross section detection is carried out from a midspan cross section to two ends at intervals of 0.2m, and the detection length range is not less than the larger value of 1/3 and 0.8m of the length of the beam purlin. If obvious internal damage is found to exist in a certain cross section, the cross section is detected in an encrypted mode, and secondary scanning is carried out on the cross section at the position of 0.1m on the left and right of the cross section with the problem.
The detection and layout principle of the cross section of the wood member with problems in the comprehensive detection is as follows: starting from any cross section where the damage is found, detection is performed every 0.1m (square column) or 0.2m (column) to both sides until no obvious internal damage is found at a certain cross section.
Step four, detecting internal damage of the wood member: and performing nondestructive detection on the detection area in the third step by adopting nondestructive detection equipment, acquiring the distribution type and rule of the internal damage of the wood member and quantitative boundary characteristics, accurately positioning the damage boundary, and outlining a three-dimensional distribution map of the internal damage.
Wherein, there is difference to the check out test set that component in different positions chose for use: the method comprises the following steps that a stress wave detector and a micro-drilling resistance instrument are adopted for a wood column and a beam purlin with the periphery completely exposed outside; the part of the wooden column which is wrapped by the wall or shielded only adopts a micro-drilling resistance meter.
Detection mechanism adopting stress wave detectorThe internal damage of the wood member is determined according to the attenuation rate of the propagation velocity of the stress wave, and the transverse propagation velocity v of the stress wave of the healthy material0The relationship with the distance l between the sensors corresponds to the formula (1):
Figure BDA0002755349510000061
in the formula, v0The unit is the transverse propagation speed of the stress wave in the healthy material and is m/s; l is the distance between two sensors of the stress wave detector, and the unit is m; t is the travel time in s, which is the average of three consecutive determinations of travel time, where the first tap travel time reading is invalid and is calculated from the second.
The internal damage of the member is detected by adopting a micro-drilling resistance instrument, the internal damage condition of the wood member is determined according to the resistance attenuation rate, and the resistance value of the healthy material is the average value of the measured values of the real wood part of the non-defective wood member. Generally, a drill of the micro-drilling resistance instrument can drill into a defect-free wood member by at least 20mm, the first 5mm is an invalid value, and the average value of the resistance at the drilling depth of 5-15 mm is taken as the resistance value of the healthy material.
Specifically, the method comprises the following steps of for a wood column 1 and a beam purlin 4 with the periphery exposed outside:
step 401, scanning the material conditions of the cross sections of a wood column 1 and a beam purlin 4 by using a stress wave tester;
it should be noted that when the stress propagation speed is reduced by more than 23% but less than 35% compared with the standard value, it indicates that decay is likely to exist inside the wood member; the stress propagation speed decreased by more than 35%, indicating that voids are likely to exist inside the wood member.
In order to further clarify the position of the damage inside the section of the component, the component is screened according to the method of figure 4 or figure 5.
Fig. 4 corresponds to a circular wood member section:
the unidirectional stress wave detection route is 4 routes at two diameters and radii 1/2 which are perpendicular to each other, namely a detection route I7, a detection route II 8, a detection route III 9, a detection route IV 10, a detection route V11 and a detection route VI 12 in the figure; and judging the position of the defect according to the stress wave speed detection result. The stress wave speed on any detection route is less than the propagation speed of the healthy material, and the existence of the defect at the position is indicated.
When the stress wave velocity at the positions of the first detection path 7 and the second detection path 8 is less than the propagation velocity in the healthy material, damage may occur near the center of the cross section;
when the stress wave velocity at the positions of the detection path four 10 and the detection path five 11 is less than the propagation velocity in the healthy material, the damage may be caused in the area one 13 in fig. 4;
when the stress wave velocity at the positions of the third detection path 9 and the fifth detection path 11 is less than that of the healthy material, damage may occur in the second region 14 in fig. 4;
when the stress wave velocity at the positions of the third detection path 9 and the sixth detection path 12 is less than that of the healthy material, damage may occur in the third area 15 in fig. 4;
when the velocity of the stress wave at the positions of the four 10 and six 12 detection paths is smaller than that of the healthy material, a damage may occur in the region four 16 in fig. 4.
Fig. 5 corresponds to a square wood member section:
the unidirectional stress wave detection route is two straight lines which respectively pass through the centers of the long side and the short side and are perpendicular to each other, and 4 routes at 1/4 and 3/4, namely a detection route seven 17, a detection route eight 18, a detection route nine 19, a detection route ten 20, a detection route eleven 21 and a detection route twelve 22 in the figure. And judging the position of the defect according to the stress wave speed detection result. The stress wave speed on any detection route is less than the propagation speed of the healthy material, and the existence of the defect at the position is indicated.
When the stress wave velocity at the position of the seven 17 and eight 18 detection paths is less than the propagation velocity in the healthy material, damage may occur near the center of the cross section;
when the stress wave velocity at the positions of the ten 20 and eleven 21 detection paths is less than the propagation velocity in the healthy material, the damage may be found in the area five 23 in fig. 5;
when the stress wave velocity at the positions of the nine 19 and eleven 21 detection paths is less than that of the healthy material, a damage may occur in the sixth 24 area in fig. 5;
when the velocity of the stress wave is smaller than that of the healthy material at the positions of the nine 19 and twelve 22 detection paths, a damage may occur in the seven 25 area in fig. 5.
When the velocity of the stress wave at the positions of the ten detection paths 20 and the twelve detection paths 22 is smaller than that of the healthy material, a damage may occur in a region eight 26 in fig. 5.
Step 402, on the basis of the problem section detected in step 401, according to the position of the plane defect displayed on the section, using a micro drilling resistance instrument to perform needle insertion detection with emphasis on a single path (radial direction or chord direction, such as a needle insertion path I27 and a needle insertion path II 28 in fig. 6 or a needle insertion path I31 and a needle insertion path II 32 in fig. 7) designated by a stress wave sensor, and accurately distinguishing the defect type and the defect length on the designated single path;
when verifying and detecting a defective part by using a micro-drilling resistance tester, if the needle is inserted from two opposite directions with the path length of more than 0.5m, the needle is inserted from one direction with the path length of less than 0.5m to penetrate the wood member.
In addition, when the average wave peak value of the attenuation section curve in the resistance diagram is 30-60% of the average wave peak value in the normal interval, the decay is judged; when the average wave peak value of the attenuation section curve is less than 30% of the average peak value of the normal interval, determining the attenuation section curve as a cavity; and when the average wave peak value of the attenuation section curve is less than 30% of the average wave peak value of the normal interval, and the interval is narrow and long, judging that the crack exists.
Step 403, performing micro-drilling detection by using a cross method, performing micro-drilling detection again along the perpendicular bisector (such as a needle insertion path three 29 and a needle insertion path four 30 in fig. 6 or a needle insertion path seven 33 and a needle insertion path eight 34 in fig. 7) of the defect area in the previous damaged position resistance value diagram, and determining a damaged boundary on each single path;
and step 404, accurately judging the internal damage profile, gradually encrypting the needle insertion times by adopting a cross method according to the field condition, realizing multi-path and multi-direction detection, and finally fitting a plane damage profile map.
Step 405, measuring the length of the defect on the single path of the damaged wood member by using the micro-drilling resistance meter, so as to obtain a more accurate defect area, wherein the calculation formula refers to the following formulas (2) and (3):
circular shape
Figure BDA0002755349510000091
Square shape
Figure BDA0002755349510000092
In the formula:
a: the area of the defect;
l27～l30: detecting the defect length by a resistance meter on a circular section single path of the component;
l31～l34: and detecting the defect length by a resistance meter on the square section single path of the component.
And 406, combining the needle insertion detection results of different problem cross sections to finally obtain a three-dimensional distribution map of internal damage.
And (3) scanning the material condition of the wood column and determining the internal damage boundary by using a micro-drilling resistance meter only for the wood column partially wrapped by the wall. Referring to fig. 8, the specific steps are as follows:
step 401, selecting the middle point of the arc of the exposed part of the column as a reference point, inserting the column through the reference point and the circular cross section to form a reference line as a needle inserting path nine 36, wherein a masonry wall 35 is further shown in the figure;
step 402, clockwise rotating the needle insertion path by 30 degrees and 60 degrees around the reference point to perform chordal detection, namely needle insertion path ten 37 and needle insertion path eleven 38;
step 403, performing chordal detection by counterclockwise rotating the needle insertion paths of 30 degrees and 60 degrees around the reference point, namely needle insertion path twelve 39 and needle insertion path thirteen 40;
and step 404, gradually encrypting needle insertion times according to the field condition for accurately judging the internal damage profile, performing secondary scanning on the needle insertion at intervals of 15 degrees between the needle insertion paths of the problem, and finally fitting a plane damage profile graph.
Step 405, measuring the length of the defect on the single path of the damaged wood member by using a resistance meter to obtain a more accurate defect area, wherein the calculation formula is referred to as formula (4)
Figure BDA0002755349510000101
In the formula:
L37～L40: the length from a base point on a single path of the resistance meter to the farthest end of the defect is the damaged boundary;
L′37～L′40: the length from the base point on the single path of the resistance meter to the damage boundary at the nearest end of the defect.
And 406, combining the needle insertion detection results of different problem cross sections to finally obtain a three-dimensional distribution map of internal damage.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent structural changes of the above embodiments according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims (4)

1. A method for detecting internal damage of an ancient building wood member is characterized by comprising the following steps:
the method comprises the following steps of firstly, determining the arrangement of a structural system and a bearing component of the historic building timber structure to be detected, retesting the outline structure size of a main component in the historic building timber structure, and providing basic data for detecting the internal damage of the timber component;
step two, generally surveying all accessible wood components of the historic building wood structure through observation and knocking, recording the material condition of the surface of the wood component, and preliminarily determining the components which are possibly damaged internally;
step three, determining key re-inspection areas of the problematic wood members and the main bearing members in the comprehensive detection in the step two, wherein the main bearing members comprise wood columns and beam beams, the detection number of the main bearing members is performed in a sampling mode, and the detection areas of the main bearing members are as follows: the wood columns are concentrated at the root parts, and the beam purlin is concentrated at the nodes of the midspan and the beam parts;
step four, performing nondestructive detection on the rechecked area in the step three by adopting nondestructive detection equipment, acquiring the distribution rule and quantitative boundary characteristics of the internal damage of the wood member, and outlining the stereoscopic distribution map of the internal damage; wherein, there is difference to the check out test set that component in different positions chose for use: the method comprises the following steps that a stress wave detector and a micro-drilling resistance instrument are adopted for a wood column and a beam purlin with the periphery completely exposed outside; the part of the wooden column wrapped by the wall or shielded only adopts a micro-drilling resistance meter;
the method comprises the following steps of for the wood columns and the beam purlin with the periphery completely exposed outside:
a401, scanning the material conditions of the cross sections of a wood column and a beam purlin by using a stress wave tester;
step A402, on the basis of detecting the problem section in the step A401, according to the position of the plane defect displayed on the section, a micro-drilling resistance instrument is used for detecting the needle with emphasis on a single path appointed by a stress wave sensor, and the defect type and the defect length are distinguished on the appointed single path;
wherein, for the section of the round wood member:
the specified single path is two mutually perpendicular diameters and 4 paths at a radius 1/2, wherein the two mutually perpendicular diameters are a detection path I (7) and a detection path II (8), the 4 paths at a radius 1/2 are a detection path III (9), a detection path IV (10), a detection path V (11) and a detection path VI (12), the detection path III (9) and the detection path IV (10) are both perpendicular to the detection path II (8) and respectively pass through 1/2 positions of two radii on the detection path II (8), and the detection path V (11) and the detection path VI (12) are both perpendicular to the detection path I (7) and respectively pass through 1/2 positions of two radii on the detection path I (7);
for a square wood member section:
the single path designated is two straight lines passing through the centers of the long and short sides respectively and perpendicular to each other and 4 routes at 1/4 and 3/4 thereof, wherein two mutually perpendicular straight lines are a detection path seven (17) and a detection path eight (18), the 4 routes at 1/4 and 3/4 are detection path nine (19), detection path ten (20), detection path eleven (21) and detection path twelve (22), the detection path nine (19) and the detection path ten (20) are both perpendicular to the detection path eight (18), and respectively passes through 1/4 position and 3/4 position of the detection path eight (18), the detection path eleven (21) and the detection path twelve (22) are both perpendicular to the detection path seven (17), and respectively passes through the 1/4 position and the 3/4 position of the detection path seven (17);
judging the position of the defect according to the stress wave speed detection result, wherein the stress wave speed on any detection route is less than the propagation speed of the healthy material, and the defect at the position is represented;
step A403, performing micro-drilling detection by adopting a cross method, performing micro-drilling detection again along the perpendicular bisector of the defect area in the resistance value diagram of the previous damaged position, and determining the damaged boundary on a single path at each time;
step A404, accurately determining an internal damage profile, gradually encrypting needle insertion times by adopting a cross method according to the field condition, realizing multi-path and multi-direction detection, and finally fitting a plane damage profile graph;
a405, measuring the length of a defect on a single path of a damaged wood member by using a micro-drilling resistance meter to obtain the area of the defect;
step A406, combining the needle insertion detection results of different problem cross sections to finally obtain a stereoscopic distribution map of internal damage;
the method comprises the following steps of:
b401, selecting the middle point of the circular arc of the exposed part of the column as a reference point, and inserting the needle through the reference point and the circular cross section to form a reference line;
step B402, clockwise rotating the needle by 30 degrees and 60 degrees around the reference point to perform chord direction detection;
step B403, performing chordal direction detection by counterclockwise rotating the needle insertion by 30 degrees and 60 degrees around the reference point;
step B404, gradually encrypting needle insertion times according to the field condition for accurately judging the internal damage profile, performing secondary scanning on needle insertion at intervals of 15 degrees between the needle insertion paths of the problem, and finally fitting a plane damage profile graph;
step B405, measuring the defect length on a single path of the damaged wood member by using a resistance meter to obtain the defect area;
and step B406, combining the needle insertion detection results of different problem cross sections to finally obtain a stereoscopic distribution map of internal damage.
2. The method for detecting internal damage of ancient building wood member according to claim 1, wherein the step one, internal damage of wood member comprises: and (2) decay or worm damage, cracks and cavities, wherein the step two of recording the material condition of the surface of the wood member comprises the following steps: knocking sound, whether water stain exists, whether wood chip exists, whether concave surface exists and fruit body.
3. The method for detecting internal damage of ancient building wood member according to claim 1, wherein the internal damage of the wood member is detected by a stress wave detector, the internal damage condition of the wood member is determined according to the attenuation rate of the propagation velocity of the stress wave, and the transverse propagation velocity v of the stress wave of the healthy material0The relationship with the distance l between the sensors corresponds to the following equation:
Figure FDA0003521210490000031
in the formula, v0The unit is the transverse propagation speed of the stress wave in the healthy material and is m/s; l is the distance between two sensors of the stress wave detector, and the unit is m; t is the travel time, in s, which is the average of three consecutive determinations of travel time, where the first tap travel time reading is invalid and is calculated from the second;
the internal damage of the member is detected by adopting a micro-drilling resistance instrument, the internal damage condition of the wood member is determined according to the resistance attenuation rate, and the resistance value of the healthy material is the average value of the measured values of the real wood part of the non-defective wood member.
4. The method for detecting internal damage of ancient building wood members according to claim 3, wherein the internal damage of the ancient building wood members is detected by using a micro-drilling resistance instrument, a drill bit of the micro-drilling resistance instrument is drilled into the wood members without defects for at least 20mm, the first 5mm is an invalid value, and the average value of resistance at the drilling depth of 5-15 mm is taken as the resistance value of the healthy material.
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