CN111077065A - Method for measuring damaged depth of concrete after high temperature through grouped compression resistance of core samples - Google Patents

Abstract

The invention discloses a method for measuring the concrete damage depth of a bridge after fire through core sample grouping compression resistance, which comprises the following steps: s1, selecting a fire area to be measured and a non-fire area as a reference on the same bridge as a calibration area; s2, drilling a damaged core sample of the high-temperature concrete in a fire area, and drilling an intact core sample in a calibration area, wherein the drilling depth of the damaged core sample and the intact core sample is h; s3, measuring the compressive strength of the intact core sample to obtain a standard value f of the compressive strength of the bridge concrete_b(ii) a S4, cutting the damaged core sample from the fire-receiving surface to different depths d_1～nAnd respectively measuring the compressive strength f of the damaged core sample after the cutting at different depths_c1～n(ii) a S5, respectively comparing f_c1～nAnd f_bWhen f is_cxAnd f_bWhen relevant, f_cxCorresponding to the cutting depth d of the damaged core sample_xThe damage depth of the fire area; the method can be used forAnd measuring the damage condition of the concrete in the depth direction when the concrete is damaged.

Description

Method for measuring damaged depth of concrete after high temperature through grouped compression resistance of core samples

Technical Field

The invention relates to the field of bridge damage detection, in particular to a method for measuring the damaged depth of concrete at high temperature through grouped compression resistance of core samples.

Background

The core drilling method for detecting the concrete strength is a relatively accurate local damage detection method, and the concrete damage condition is evaluated by comparing and analyzing the compressive strengths of grouped core samples after the core samples are drilled and manufactured on the structure. However, the strength of the concrete measured by this method is an average strength value of the core sample, and damage in the depth direction cannot be considered.

Disclosure of Invention

The present invention is directed to overcoming at least one of the above-mentioned disadvantages (shortcomings) of the prior art, and provides a method for measuring a damaged depth of concrete after a high temperature by using a core sample group compression resistance, which is used to solve a damage situation in a depth direction when the concrete is damaged.

The technical scheme adopted by the invention is that,

a method for measuring the damage depth of bridge concrete after fire by core sample grouping compression resistance comprises the following steps:

s1, selecting a fire area to be measured and a non-fire area as a reference on the same bridge as a calibration area;

s2, drilling a damaged core sample of the high-temperature concrete in a fire area, and drilling an intact core sample in a calibration area, wherein the drilling depth of the damaged core sample and the intact core sample is h;

s3, measuring the compressive strength of the intact core sample to obtain a standard value f of the compressive strength of the bridge concrete_b；

S4, cutting the damaged core sample from the fire-receiving surface to different depths d_1～nAnd respectively measuring the compressive strength f of the damaged core sample after the cutting at different depths_c1～n；

S5, respectively comparing f_c1～nAnd f_bWhen f is_cxAnd f_bWhen relevant, f_cxCorresponding to the cutting depth d of the damaged core sample_xThe depth of damage in the fire zone.

Compressive strength f of intact core sample sampled in the area of non-fired_bThe standard compressive strength of the undamaged bridge concrete is used for comparing the standard compressive strength with the compressive strength of a damaged core sample sampled in a fire passing area to obtain the damaged depth of the damaged core sample, and the damaged core sample is cut off at different depths d from a fire receiving surface_1～nTo obtain different compressive strengths f_c1～nWhen the compressive strength f is as high as that of a damaged core_cxAnd f_bThe equivalent indicates that the damaged core sample has no damaged part, i.e. the damaged part is cut off, so the cutting depth d_xI.e. the damaged depth of the damaged core.

Further, in the step S4, the damaged core samples are divided into n groups, and each group is cut from the fire surface of the damaged core sample by the depth d_nDepth of excision d for each group_1～nDifferent; the depth d of the resection_1～nGradually excising at equal intervals by unit, wherein the unit excising depth is delta, and the length l of each group of damaged core samples after excising_n＝h-d_n＝h-δ(n-1)，n≥1。

Gradually excising the damaged core samples at equal intervals, dividing the damaged core samples with different excising depths into n groups, wherein the depth difference between each group of core samples is delta, and obtaining the excising depth d of each group of damaged core samples_nδ (n-1), n ≧ 1, length l_n＝h-d_nThe damage depth of the damaged core sample can be measured more accurately by equidistant stepwise cutting as h-delta (n-1) and n is more than or equal to 1.

Further, in step S1, a boundary line of a fire area is determined according to actual conditions of the fire, and an area that is 20cm away from the boundary line is divided into the calibration area; in the step S2, the damaged core sample and the sound core sample are sampled on the same member of the bridge, the sampling range of the sound core sample on the calibration area is controlled between 20cm and 75cm from the boundary line, and the sampling path extends along the path direction of the boundary line.

Because the boundary line of the fire area and the calibration area is fuzzy and is not an exact boundary line, if sampling is directly carried out on two sides of the boundary line, the situation that errors occur when the intact core sample and/or the damaged core sample are/is measured is easily caused, the calibration area is controlled to be beyond 20cm of the boundary line, the sampling range is controlled to be between 20cm and 75cm away from the boundary line, the sampling path extends along the path direction of the boundary line, the error situation can be reduced, and meanwhile, the situation that the errors are caused due to different members can be reduced when the damaged core sample and the intact core sample are sampled on the same member of the bridge.

Further, the method for measuring the concrete damage depth of the bridge after the fire through core sample grouping compression resistance is characterized in that in the step S1, the boundary line of the fire area is determined through an appearance method according to the actual situation of the fire and different temperature areas are estimated; in step S2, the damaged core sample is drilled in a temperature range of 500 ℃ or higher.

Further, the method for measuring the concrete damage depth of the bridge after the fire through core sample grouping compression resistance is characterized in that in the step S1, the apparent method estimates that different temperature areas are executed according to the following standards:

temperature/. degree.C	＜200	300～500	500～700	700～800	＞800
						Colour(s)	Grey leaf of Chinese Grey greenish blue	Light gray and pink	Pale white and light red	Pale white and pale yellow	Light yellow
Burst and spall	Is free of	Local whitewash layer	Corner concrete	Large area of	Loose and large area
						Cracking of	Is free of	Micro cracks	Having cracks at corners	More cracks	Through crack
Hammer action	Loud sound	Loud sound	The sound is stuffy	Sound smothering	Sound mute

The appearance method is mainly used for preliminarily judging fire field subareas, can intuitively and quickly analyze the fire field subareas in a short time, can estimate areas with different temperatures in a fire area through the surface color and the appearance characteristics of a concrete structure, and is more favorable for accurately measuring the damage depth and the deepest damage depth of the bridge by selecting the temperature area more than or equal to 500 ℃ after the temperature area is determined.

Further, the method for measuring the damage depth of the bridge concrete after the fire through the grouped compression resistance of the core samples is characterized in that in the step S2, the damaged core samples are respectively drilled in three temperature regions of 500-700 ℃, 700-800 ℃ and above 800 ℃, and the steps S4 and S5 are respectively carried out to obtain the corresponding damage depth d_x500、d_x700And d_x800Through d_x500、d_x700And d_x800And calculating the equivalent damage depth D of the bridge member.

After the damage depths of the damaged core samples in three temperature areas of 500-700 ℃, 700-800 ℃ and above 800 ℃ are measured, the equivalent damage depth of the bridge member after fire can be calculated according to the damage depths in the three areas, and the equivalent damage depth can be used for evaluating the overall damage condition of the bridge after fire.

Further, the method for measuring the concrete damage depth of the bridge after the fire through grouped compression resistance of the core samples is characterized in that in the step S2, the damaged core samples and the intact core samples are cylinders with the cross section diameter of 5.5-10.5 cm and the drilling depth of 20-30 cm, and reinforcing steel bar reinforcement is avoided at the positions of the sampling points; when the sampling area of the damaged core sample is in a belt shape, sampling points extend and are distributed in the middle of the belt shape along the direction of the belt-shaped path; when the sampling area of the damaged core sample is planar, the sampling points are distributed in an equilateral triangle in the planar area.

The damaged core sample and the intact core sample cannot be too large, otherwise, the function and the safety of the bridge are affected, so that the size of the sample is controlled to be a cylinder with the cross section diameter of 5.5-10.5 cm and the drilling depth of 20-30 cm; the sample application position needs to avoid reinforcing steel bar reinforcement, otherwise, the function and the safety of the bridge are affected; when the area of the damaged core sample is in a belt shape, the point sample is extended and distributed in the middle of the belt shape along the direction of the belt-shaped path, so that uniform sampling is facilitated, and errors are reduced; similarly, when the sampling area of the damaged core sample is planar, the sampling points are distributed in an equilateral triangle in the planar area, which is beneficial to uniform sampling and reduces errors.

When the fire surface of the damaged core sample is peeled off, firstly, the fire surface of the damaged core sample is subjected to flat cutting treatment;

the step S4 specifically includes:

s41, finding out the damaged core sample with the most serious peeling from all damaged core samples, and determining the flat cutting depth h by taking the maximum peeling depth as a reference_p；

S42, according to h_pSubjecting all damaged core samples to fire surface flat cutting treatment to make each damaged core sample have uniform length h-h before being cut off step by step_p；

S43, gradually cutting off each group of damaged core samples subjected to flat cutting treatment, wherein the length l of each group of damaged core samples is obtained after cutting off_n＝h-d_n＝h-h_p-δn，

d_n＝h_p+δ(n-1)，n≥1；

The step S5 specifically includes:

s51, starting from the condition that i is equal to 1, measuring the length l one by one through a pressure test_iCompressive strength f of the damaged core sample_ci；

S52, comparison f_ciAnd f_bThe size of (c), judgment f_ciWhether or not it falls into f_b(1 ± 10%);

s53, if the interval is within, continuing to measure f_c(i+1)And f_c(i+2)Whether or not it falls into f_b(1 ± 10%);

s54. if f_c(i+1)And f_c(i+2)Are all within the interval, then f is determined_ciIs f_cxAnd f_bEquivalent; s55, determining f_ciIs corresponding to d_i＝h_p+ δ i is the damage depth d_x。

In step S4, since peeling of the damaged core specimen has an effect on the accuracy of the deep cutting of the damaged core specimen, it is necessary to perform a slicing process, and after finding the damaged core specimen most likely to peel, the damaged core specimen is accurately cut based on the maximum peeling depthAll damaged core samples are cut flatly, and the flat cutting depth is h_pSo that the length of each damaged core sample after the uniform slicing treatment is h-h_pGradually cutting off each group of damaged core samples after the flat cutting treatment, wherein the length l of each group of damaged core samples after cutting off_n＝h-d_n＝h-h_pδ n, to yield d_n＝h_p+δ(n-1)，n≥1。

In step S5, starting from i ═ 1, length l is measured one by a pressure test_iCompressive strength f of the damaged core sample_ciObtaining the standard compressive strength f of each damaged core sample and the intact core sample_bComparing the sizes and judging f_ciWhether or not it falls into f_b(1. + -. 10%) due to unavoidable errors in the experiment, f_bThe interval of (1. + -. 10%) is an interval of an acceptable error range, so f_ciAnd f_b(1 +/-10%) interval to make size comparison; such as f_ciDuring this interval, continue to measure f_c(i+1)And f_c(i+2)Whether or not it falls into f_b(1. + -. 10%) due to f_ciIn the interval, which may be accidental, if the damaged core is a critical value for the damage of the core, the compressive strength after the continuous cutting should remain stable, so that a further measurement of f is required_c(i+1)And f_c(i+2)Whether or not it falls into f_b(1. + -. 10%) in the interval, e.g. f_c(i+1)And f_c(i+2)All fall into f_b(1. + -. 10%) in the interval, f is proved_ciAnd f_bRather, f can be determined_ciIs corresponding to d_i＝h_p+ δ i is the damage depth d_x。

Further, when the fire surface of the damaged core sample is peeled off, firstly, the fire surface of the damaged core sample is subjected to flat cutting treatment; the step S4 specifically includes:

s41, respectively finding out one damaged core sample with the most serious peeling from the damaged core samples in the three temperature areas, and determining the flat cutting depth h of the three temperature areas by taking the maximum peeling depth as a reference_p500、h_p700And h_p800；

S42, according to h_p500、h_p700And h_p800Respectively carrying out fire-receiving surface flat cutting treatment on the damaged core samples in the three temperature areas, so that the damaged core samples in each temperature area have uniform lengths h-h before being gradually cut off_p500、h-h_p700And h-h_p800；

S43, gradually cutting off each group of damaged core samples in the three temperature areas after the flat cutting treatment, wherein the length of each group of damaged core samples in the three temperature areas after cutting off is respectively as follows:

l_n500＝h-d_n500＝h-h_p500-δ(n-1)，n≥1，d_n500＝h_p500+δn；

l_n700＝h-d_n700＝h-h_p700-δ(n-1)，n≥1，d_n700＝h_p700+δn；

l_n800＝h-d_n800＝h-h_p800-δ(n-1)，n≥1，d_n800＝h_p800+δn；

the step S5 performed on the three temperature regions includes:

s51, starting from i, j and k equal to 1, measuring the length l one by one through a pressure test_500i、l_700iOr l_800iCompressive strength f of the damaged core sample_c500i、f_c700jOr f_c800k；

S52, respectively comparing f_c500i、f_c700jOr f_c800kAnd f_bThe size of (c), judgment f_c500i、f_c700jOr f_c800kWhether or not it falls into f_b(1 ± 10%);

s53, if the interval is within, continuing to measure f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Whether or not it falls into f_b(1 ± 10%);

s54. if f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Are all within the interval, then f is determined_c500i、f_c700jOr f_c800kIs f_cxAnd f_bEquivalent;

s55, determining f_c500i、f_c700jOr f_c800kIs corresponding to d_i＝h_p500+δi、d_j＝h_p500+ δ j or d_k＝h_p500+ δ k is the damage depth d corresponding to three temperature regions respectively_x500、d_x700And d_x800；

S56, passing through d_x500、d_x700And d_x800And calculating the equivalent damage depth D of the bridge member.

In step 4, the damaged core samples sampled in the three temperature regions are uniformly subjected to a flat cutting treatment and then are gradually cut off to obtain the lengths of the damaged core samples in the three temperature regions: l_n500＝h-d_n500＝h-h_p500-δ(n-1)，l_n700＝h-d_n700＝h-h_p700-δ(n-1)，l_n800＝h-d_n800＝h-h_p800Delta (n-1), n is not less than 1, giving d_n500＝h_p500+δ(n-1)，n≥1，d_n700＝h_p700+δ(n-1)；，d_n800＝h_p800+δ(n-1)；

In step 5, the compressive strength f of the damaged core specimen in each temperature region is measured starting from i, j, k equal to 1_c500i、f_c700jAnd f_c800kAnd standard compressive strength f of intact core specimen_bComparing and judging f_c500i、f_c700jAnd f_c800kWhether or not it falls into f_b(1. + -. 10%) due to unavoidable errors in the experiment, f_bThe interval of (1. + -. 10%) is an interval of an acceptable error range, so f_c500i、f_c700jAnd f_c800kAnd f_b(1 +/-10%) interval to make size comparison; such as f_c500i、f_c700jAnd f_c800kDuring this interval, continue to measure f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Whether or not it falls into f_b(1. + -. 10%) due to f_c500i、f_c700jAnd f_c800kIn this interval it may be evenHowever, if the damaged core is critical for the damage of the core, the compressive strength after the cutting should remain stable, and further measurement of f is needed_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Whether or not it falls into f_b(1. + -. 10%) in the interval, e.g. f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)All fall into f_b(1. + -. 10%) in the interval, f is proved_c500i、f_c700jAnd f_c800kAnd f_bRather, determine f_c500i、f_c700jOr f_c800kIs corresponding to d_i＝h_p500+δ(i-1)、d_j＝h_p500+ delta (j-1) or d_k＝h_p500+ delta (k-1) is the damage depth d corresponding to three temperature regions respectively_x500、d_x700And d_x800Finally by d_x500、d_x700And d_x800The equivalent damage depth D of the bridge member may be calculated.

Further, in the step S56, the equivalent damaged depth D ═ D_x500×0.5+d_x700×0.3+d_x800×0.2。

When the equivalent damage depth is calculated, the damage depths of the damaged core samples in the three temperature regions are calculated according to different proportions, the damaged core samples in the temperature region 500-700 ℃ account for 50%, the damaged core samples in the temperature region 700-800 ℃ account for 30%, and the damaged core samples in the temperature region above 800 ℃ account for 20%, so that the equivalent damage depth D-D of the bridge member is calculated_x500×0.5+d_x700×0.3+d_x800×0.2。

Compared with the prior art, the invention has the beneficial effects that: the compressive strength of the core sample is compared by gradually cutting off the core sample, the damage depth of the core sample is measured, and the actual damage depth of the concrete after fire can be measured by the method, so that the damage condition of the concrete can be further known and analyzed.

Drawings

FIG. 1 is a structural diagram of a damaged core specimen and a sound core specimen in example 1.

FIG. 2 is a distribution diagram of the apparent method of estimating the temperature region of the fire zone in example 2.

FIG. 3 is a structural diagram of a damaged core specimen and a sound core specimen in example 2.

FIG. 4 is a schematic diagram showing the sampling of the band-shaped damaged area in example 3.

FIG. 5 is a schematic view showing the sampling of the planar damaged area in example 4.

Detailed Description

The drawings are only for purposes of illustration and are not to be construed as limiting the invention. For a better understanding of the following embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

Example 1

As shown in fig. 1, the present embodiment is a method for measuring the damage depth of the bridge concrete after fire by core-sample component compression resistance, comprising the following steps:

s1, selecting a fire area to be measured and a non-fire area as a reference on the same bridge as a calibration area;

s2, drilling a damaged core sample of the high-temperature concrete in a fire area, and drilling an intact core sample in a calibration area, wherein the drilling depth h of the damaged core sample and the intact core sample is 20 cm;

s3, measuring the compressive strength of the intact core sample to obtain a standard value f of the compressive strength of the bridge concrete_b；

S4, cutting the damaged core sample from the fire-receiving surface to different depths d_1～nAnd respectively measuring the compressive strength f of the damaged core sample after the cutting at different depths_c1～n；

S5, respectively comparing f_c1～nAnd f_bWhen f is_cxAnd f_bWhen relevant, f_cxCorresponding to the cutting depth d of the damaged core sample_xThe depth of damage in the fire zone.

Furthermore, the bridge concrete receiver after fire hazard is measured through core sample grouping compression resistanceMethod for depth of damage, characterized in that in step S4, the damaged core samples are divided into 10 groups, i.e. 1. ltoreq. n.ltoreq.10, each group having a cutting depth d_1～nDifferent; the depth d of the resection_1～nGradually excising at unit equal distance, wherein the unit excising depth delta is 5mm, the first group excising depth is 0mm, and the length l of each group of damaged core samples after excising_n＝h-d_n＝h-δ(n-1)＝200-d_n200-5(n-1), 1 ≤ n ≤ 10, and the unit is mm.

In the 10 groups of damaged core samples, 5 damaged core samples in each group are provided, 50 damaged core samples are totally provided, the 50 damaged core samples are respectively subjected to a compressive strength test, and the compressive strength of the damaged core samples in each group is averaged to be used as the compressive strength f of the damaged core samples in each group_cn5 samples of the intact core samples are respectively subjected to a compression strength test, and the average value of the compression strengths of the intact core samples is used as a standard compression strength f_bAnd further adjusting the compressive strength f of each group of damaged core samples_cnWith standard compressive strength f_bCarrying out comparative analysis;

further, in step S1, a boundary line of a fire area is determined according to actual conditions of the fire, and an area that is 20cm away from the boundary line is divided into the calibration area; in step S2, the damaged core sample and the sound core sample are sampled on the same member of the bridge, the sampling range of the sound core sample on the calibration area is controlled between 50cm from the boundary line, and the sampling path is extended along the path direction of the boundary line.

Further, in the step S2, the damaged core sample and the intact core sample are cylinders with a cross section diameter of 5.5cm and a drilling depth of 20cm, and the position of the sampling point avoids the reinforcing steel bar arrangement of the bridge. When the sampling area of the damaged core sample is in a belt shape, sampling points extend and are distributed in the middle of the belt shape along the direction of the belt-shaped path; when the sampling area of the damaged core sample is planar, the sampling points are distributed in an equilateral triangle in the planar area.

Further, when the fire surface of the damaged core sample is peeled off, firstly, the fire surface of the damaged core sample is subjected to flat cutting treatment; the step S4 specifically includes:

s41, as shown in figure 1, finding out the damaged core sample A with the most serious stripping from all damaged core samples, and determining the flat cutting depth h by taking the maximum stripping depth as a reference_pIs 3 mm;

s42, according to h_pSubjecting all damaged core samples to fire surface flat cutting treatment to make each damaged core sample have uniform length of h-h before being cut off gradually_p＝197mm；

S43, gradually cutting off each group of damaged core samples subjected to flat cutting treatment, wherein the length l of each group of damaged core samples is obtained after cutting off_n＝h-d_n＝h-h_p-δ(n-1)＝197-5(n-1)，d_n＝h_p+δ(n-1)＝3+5(n-1)，1≤n≤10；

The step S5 specifically includes:

s51, starting from i-1 to i-10, measuring the length l one by one through a pressure test_iCompressive strength f of the damaged core sample_ci；

S52, comparison f_ciAnd f_bThe size of (c), judgment f_ciWhether or not it falls into f_b(1 ± 10%);

s53, if the interval is within, continuing to measure f_c(i+1)And f_c(i+2)Whether or not it falls into f_b(1 ± 10%);

s54. if f_c(i+1)And f_c(i+2)Are all within the interval, then f is determined_ciIs f_cxAnd f_bEquivalent;

s55, determining f_ciIs corresponding to d_i＝h_p+ delta (i-1) being the depth of damage d_x。

The test results show that the average value of the compressive strength of the intact core sample is 51.9MPa, and the average value f of the compressive strength of the damaged core samples of the 1 st to 6 th groups_c1～6Are all less than f_bThe 7 th group of damaged core sample is a core sample cut by 30mm, the compressive strength of the core sample is 39-66.4 MPa, and the average compressive strength f_c7Is 50.1MPa and falls within f_b(1. + -. 10%) of the average compressive strength f of the 8 th and 9 th groups was measured_c8And f_c9Result is f_c7And f_c8All fall into f_b(1 ± 10%) of the damaged core samples, the average compressive strength f of the damaged core sample of the 7 th group when i is 7 can be determined_c7And f_bIs equal to f_c7Corresponding d₇The damage depth of the bridge after a fire, d₇＝3+5×6＝33mm。

Example 2

The embodiment provides a method for measuring damage depth of bridge concrete in different temperature areas after fire by core sample component compression resistance, which comprises the following steps:

s1, selecting a fire area to be measured and a non-fire area as a reference on the same bridge as a calibration area;

s2, drilling a damaged core sample of the high-temperature concrete in a fire area, and drilling an intact core sample in a calibration area, wherein the drilling depth h of the damaged core sample and the intact core sample is 20 cm;

s3, measuring the compressive strength of the intact core sample to obtain a standard value f of the compressive strength of the bridge concrete_b；

S4, cutting the damaged core sample from the fire-receiving surface to different depths d_1～nAnd respectively measuring the compressive strength f of the damaged core sample after the cutting at different depths_c1～n；

S5, respectively comparing f_c1～nAnd f_bWhen f is_cxAnd f_bWhen relevant, f_cxCorresponding to the cutting depth d of the damaged core sample_xThe damage depth of the fire area;

further, as shown in fig. 2, in step S1, a boundary line of a fire area is determined by an appearance method according to an actual situation of a fire, an area other than the area 20cm from the boundary line is divided into the calibration areas, and different temperature areas are estimated, wherein an area a is a calibration area which is a non-overfire area, an area B is an area having a temperature of 500 to 700 ℃, an area C is an area having a temperature of 700 to 800 ℃, and an area D is an area having a temperature of 800 ℃ or higher, and the intact core sample is sampled in the area a.

Further, in the step S2, the damaged core sample and the sound core sample are sampled on the same member of the bridge, the sampling range of the sound core sample on the calibration area is controlled between 20cm and 75cm from the boundary line, and the sampling path is extended along the path direction of the boundary line.

Further, in the step S4, the damaged core samples are divided into n groups, and each group is cut from the fire surface of the damaged core sample by the depth d_nDepth of excision d for each group_1～nDifferent; the depth d of the resection_1～nGradually excising at equal intervals by unit, wherein the unit excising depth is delta, and the length l of each group of damaged core samples after excising_n＝h-d_n＝h-δ(n-1)，n≥1。

In the n groups of damaged core samples, 5 damaged core samples in each group are provided, 5n damaged core samples in total are respectively subjected to compressive strength tests, and the average value of the compressive strength of the damaged core samples in each group is used as the compressive strength f of each group of damaged core samples_cn5 samples of the intact core samples are respectively subjected to a compression strength test, and the average value of the compression strengths of the intact core samples is used as a standard compression strength f_bAnd further adjusting the compressive strength f of each group of damaged core samples_cnWith standard compressive strength f_bComparative analysis was performed.

Further, in the method for measuring the concrete damage depth of the bridge after the fire through core sample grouping compression resistance, in the step S1, the apparent method estimates that different temperature regions are executed according to the following criteria:

temperature/. degree.C	＜200	300～500	500～700	700～800	＞800
						Colour(s)	Grey leaf of Chinese Grey greenish blue	Light gray and pink	Pale white and light red	Pale white and pale yellow	Light yellow
Burst and spall	Is free of	Local whitewash layer	Corner concrete	Large area of	Loose and large area
						Cracking of	Is free of	Micro cracks	Having cracks at corners	More cracks	Through crack
Hammer action	Loud sound	Loud sound	The sound is stuffy	Sound smothering	Sound mute

Further, in the step S2, the damaged core sample and the intact core sample are sampled as cylinders with a cross section diameter of 5.5cm and a drilling depth of 20cm, and the positions of the sampling points avoid reinforcing steel bar reinforcement;

when the sampling area of the damaged core sample is in a belt shape, sampling points extend and are distributed in the middle of the belt shape along the direction of the belt-shaped path;

when the sampling area of the damaged core sample is planar, the sampling points are distributed in an equilateral triangle in the planar area.

Further, in the step S2, the damaged core sample is drilled in three regions B, C, D, and the steps S4 and S5 are performed to obtain the corresponding damaged depth d_x500，d_x700And d_x800Through d_x500、d_x700And d_x800And calculating the equivalent damage depth D of the bridge member.

Further, the step S4 is specifically:

s41, respectively finding out one damaged core sample with the most serious peeling from the damaged core samples in the three temperature areas, as shown in fig. 3, the damaged core samples with the most serious peeling of the damaged core samples in the three temperature areas are the damaged core sample p in the B area, the damaged core sample q in the C area and the damaged core sample s in the D area, shadow parts are the peeled parts of the core samples, and the flat cutting depths h of the three temperature areas are determined by taking the maximum peeling depth as a reference_p500、h_p700And h_p800；

S42, according to h_p500、h_p700And h_p800Respectively carrying out fire-receiving surface flat cutting treatment on the damaged core samples in the three temperature areas, so that the damaged core samples in each temperature area have uniform lengths h-h before being gradually cut off_p500、h-h_p700And h-h_p800；

S43, gradually cutting off each group of damaged core samples in the three temperature areas after the flat cutting treatment, wherein the length of each group of damaged core samples in the three temperature areas after cutting off is respectively as follows:

l_n500＝h-d_n500＝h-h_p500-δ(n-1)，d_n500＝h_p500+δ(n-1)，n≥1；

l_n700＝h-d_n700＝h-h_p700-δ(n-1)，d_n700＝h_p700+δ(n-1)，n≥1；

l_n800＝h-d_n800＝h-h_p800-δ(n-1)，d_n800＝h_p800+δ(n-1)，n≥1；

the step S5 performed on the three temperature regions includes:

s51, starting from i, j and k equal to 1, measuring the length l one by one through a pressure test_500i、l_700iOr l_800iCompressive strength f of the damaged core sample_c500i、f_c700jOr f_c800k；

S52, respectively comparing f_c500i、f_c700jOr f_c800kAnd f_bThe size of (c), judgment f_c500i、f_c700jOr f_c800kWhether or not it falls into f_b(1 ± 10%);

s53, if the interval is within, continuing to measure f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Whether or not it falls into f_b(1 ± 10%);

s54. if f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Are all within the interval, then f is determined_c500i、f_c700jOr f_c800kIs f_cxAnd f_bEquivalent;

s55, determining f_c500i、f_c700jOr f_c800kIs corresponding to d_i＝h_p500+δ(i-1)、d_j＝h_p500+ delta (j-1) or d_k＝h_p500+ delta (k-1) is the damage depth d corresponding to three temperature regions respectively_x500、d_x700And d_x800；

S56, passing through d_x500、d_x700And d_x800And calculating the equivalent damage depth D of the bridge member.

The test results are d_x500About 4cm, d_x700About 8cm, d_x800About 11 cm.

Further, in the step S56, the equivalent damaged depth D ═ D_x500×0.5+d_x700×0.3+d_x800×0.2。

D＝d_x500×0.5+d_x700×0.3+d_x800×0.2＝4×0.5+8×0.3+11×0.2＝6.6cm。

Example 3

As shown in fig. 4, this example is a sampling method in the case where the damaged core sample sampling area in examples 1 and 2 is a belt-like damaged area of the bridge concrete after a fire, and black dots are sampling points of the damaged core sample, which are distributed in the belt-like damaged area extending in the belt-like path direction.

Further, as shown in fig. 4, the distance between the sampling points is the same in the band-shaped damaged area, and is t.

Example 4

As shown in fig. 5, this example is a sampling method in the case where the damaged core sample sampling area in examples 1 and 2 is planar, in the figure, the damaged area of the bridge concrete planar after the fire, in the figure, the black dots are the sampling points of the damaged core sample, the sampling points are distributed in an equilateral triangle in the planar area, and the distance between the sampling points on the planar damaged area is t.

It should be understood that the above-mentioned embodiments of the present invention are only examples for clearly illustrating the technical solutions of the present invention, and are not intended to limit the specific embodiments of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention claims should be included in the protection scope of the present invention claims.

Claims (10)

1. A method for measuring the damage depth of bridge concrete after fire through core sample grouping compression resistance is characterized by comprising the following steps:

s1, selecting a fire area to be measured and a non-fire area as a reference on the same bridge as a calibration area;

s2, drilling a damaged core sample of the high-temperature concrete in a fire area, and drilling an intact core sample in a calibration area, wherein the drilling depth of the damaged core sample and the intact core sample is h;

s3, measuring the resistance of the intact core sampleObtaining the standard value f of the compressive strength of the bridge concrete through the compressive strength_b；

S4, cutting the damaged core sample from the fire-receiving surface to different depths d_1～nAnd respectively measuring the compressive strength f of the damaged core sample after the cutting at different depths_c1～n；

S5, respectively comparing f_c1～nAnd f_bWhen f is_cxAnd f_bWhen relevant, f_cxCorresponding to the cutting depth d of the damaged core sample_xThe depth of damage in the fire zone.

2. The method for measuring concrete damage depth of bridge after fire through grouped compression resistance of core samples according to claim 1, wherein in the step S4, the damaged core samples are divided into n groups, and each group is cut off from the fire surface of the damaged core sample by a depth d_nDepth of excision d for each group_1～nDifferent; the depth d of the resection_1～nGradually excising at equal intervals by unit, wherein the unit excising depth is delta, and the length l of each group of damaged core samples after excising_n＝h-d_n＝h-δ(n-1)，n≥1。

3. The method for measuring the concrete damage depth of the bridge after the fire through the core sample group compression resistance according to claim 2, wherein in the step S1, the boundary line of the fire area is determined according to the actual situation of the fire, and the area beyond 20cm from the boundary line is divided into the calibration area; in the step S2, the damaged core sample and the sound core sample are sampled on the same member of the bridge, the sampling range of the sound core sample on the calibration area is controlled between 20cm and 75cm from the boundary line, and the sampling path extends along the path direction of the boundary line.

4. The method for measuring concrete damage depth of an axle beam after a fire through core sample group compression resistance according to claim 3, wherein in the step S1, boundary lines of fire regions are determined by an appearance method according to actual conditions of the fire and different temperature regions are estimated; in step S2, the damaged core sample is drilled in a temperature range of 500 ℃ or higher.

5. The method for measuring concrete damage depth of an axle beam after a fire through core sample group compression resistance according to claim 4, wherein in the step S1, the apparent method estimates that different temperature regions are performed according to the following criteria:

6. the method for measuring the damage depth of the bridge concrete after fire through grouped compression resistance of core samples according to claim 5, wherein in the step S2, the damaged core samples are respectively drilled in three temperature regions of 500-700 ℃, 700-800 ℃ and above 800 ℃, and the steps S4 and S5 are respectively carried out to obtain the corresponding damage depth d_x500、d_x700And d_x800Through d_x500、d_x700And d_x800And calculating the equivalent damage depth D of the bridge member.

7. The method for measuring the concrete damage depth of the bridge after the fire through the grouped compression resistance of the core samples according to any one of claims 1 to 6, wherein in the step S2, the damaged core sample and the intact core sample are sampled to be cylinders with the cross section diameter of 5.5-10.5 cm and the drilling depth of 20-30 cm, and the positions of the sampling points avoid reinforcing steel bars;

when the sampling area of the damaged core sample is in a belt shape, sampling points extend and are distributed in the middle of the belt shape along the direction of the belt-shaped path;

when the sampling area of the damaged core sample is planar, the sampling points are distributed in an equilateral triangle in the planar area.

8. The method for measuring the damage depth of the bridge concrete after fire through the grouped compression resistance of the core sample according to any one of claims 2 to 5,

when the fire surface of the damaged core sample is peeled off, firstly, the fire surface of the damaged core sample is subjected to flat cutting treatment;

the step S4 specifically includes:

s41, finding out the damaged core sample with the most serious peeling from all damaged core samples, and determining the flat cutting depth h by taking the maximum peeling depth as a reference_p；

S42, according to h_pSubjecting all damaged core samples to fire surface flat cutting treatment to make each damaged core sample have uniform length h-h before being cut off step by step_p；

S43, gradually cutting off each group of damaged core samples subjected to flat cutting treatment, wherein the length l of each group of damaged core samples is obtained after cutting off_n＝h-d_n＝h-h_p-δ(n-1)，d_n＝h_p+δ(n-1)，n≥1；

The step S5 specifically includes:

s51, starting from the condition that i is equal to 1, measuring the length l one by one through a pressure test_iCompressive strength f of the damaged core sample_ci；

S52, comparison f_ciAnd f_bThe size of (c), judgment f_ciWhether or not it falls into f_b(1 ± 10%);

s53, if the interval is within, continuing to measure f_c(i+1)And f_c(i+2)Whether or not it falls into f_b(1 ± 10%);

s54. if f_c(i+1)And f_c(i+2)Are all within the interval, then f is determined_ciIs f_cxAnd f_bEquivalent;

s55, determining f_ciIs corresponding to d_i＝h_p+ delta (i-1) being the depth of damage d_x。

9. The method for measuring the concrete damage depth of the bridge after fire through core sample group compression resistance according to claim 6,

when the fire surface of the damaged core sample is peeled off, firstly, the fire surface of the damaged core sample is subjected to flat cutting treatment;

the step S4 specifically includes:

s41, respectively finding out one damaged core sample with the most serious peeling from the damaged core samples in the three temperature areas, and determining the flat cutting depth h of the three temperature areas by taking the maximum peeling depth as a reference_p500、h_p700And h_p800；

S42, according to h_p500、h_p700And h_p800Respectively carrying out fire-receiving surface flat cutting treatment on the damaged core samples in the three temperature areas, so that the damaged core samples in each temperature area have uniform lengths h-h before being gradually cut off_p500、h-h_p700And h-h_p800；

S43, gradually cutting off each group of damaged core samples in the three temperature areas after the flat cutting treatment, wherein the length of each group of damaged core samples in the three temperature areas after cutting off is respectively as follows:

l_n500＝h-d_n500＝h-h_p500-δ(n-1)，d_n500＝h_p500+δ(n-1)，n≥1；

l_n700＝h-d_n700＝h-h_p700-δ(n-1)，d_n700＝h_p700+δ(n-1)，n≥1；

l_n800＝h-d_n800＝h-h_p800-δ(n-1)，d_n800＝h_p800+δ(n-1)，n≥1；

the step S5 performed on the three temperature regions includes:

s51, starting from i, j and k equal to 1, measuring the length l one by one through a pressure test_500i、l_700iOr l_800iCompressive strength f of the damaged core sample_c500i、f_c700jOr f_c800k；

S52, respectively comparing f_c500i、f_c700jOr f_c800kAnd f_bThe size of (c), judgment f_c500i、f_c700jOr f_c800kWhether or not it falls into f_b(1 ± 10%);

s53, if the interval is within, continuing to measure f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Whether or not it falls into f_b(1 ± 10%);

s54. if f_c500(i+1)、f_c700(j+1)Or f_c800(k+1)And f_c500(i+2)、f_c700(j+2)Or f_c800(k+2)Are all within the interval, then f is determined_c500i、f_c700jOr f_c800kIs f_cxAnd f_bEquivalent;

s55, determining f_c500i、f_c700jOr f_c800kIs corresponding to d_i＝h_p500+δ(i-1)、d_j＝h_p500+ delta (j-1) or d_k＝h_p500+ delta (k-1) is the damage depth d corresponding to three temperature regions respectively_x500、d_x700And d_x800；

S56, passing through d_x500、d_x700And d_x800And calculating the equivalent damage depth D of the bridge member.

10. The method for measuring concrete damage depth of bridge after fire through core-sample group compression resistance according to claim 9, wherein in the step S56, equivalent damage depth D ═ D_x500×0.5+d_x700×0.3+d_x800×0.2。

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