JP6074936B2 - Method for estimating the extent to which the compressive strength of concrete is decreasing in concrete structures - Google Patents
Method for estimating the extent to which the compressive strength of concrete is decreasing in concrete structures Download PDFInfo
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本発明は、コンクリート構造物においてコンクリートの圧縮強度が低下している範囲を推定する方法に関する。 The present invention relates to a method for estimating a range in which the compressive strength of concrete is reduced in a concrete structure.
コンクリート構造物におけるコンクリートの圧縮強度を推定する方法として、シュミットハンマーなるテストハンマーを用いた方法が知られている（例えば、特許文献１参照）。このシュミットハンマーを用いたコンクリートの圧縮強度の推定方法は、シュミットハンマーによりコンクリートの表面に打撃を与え、その際の反発硬度に基づいてコンクリートの圧縮強度を推定するというものである。 As a method for estimating the compressive strength of concrete in a concrete structure, a method using a test hammer called a Schmitt hammer is known (for example, see Patent Document 1). This method of estimating the compressive strength of concrete using a Schmitt hammer is to strike the concrete surface with a Schmitt hammer and estimate the compressive strength of the concrete based on the rebound hardness at that time.
ところで、例えば、火災により火害を受けたコンクリート構造物の表面をはつって補修や補強を行う場合等、はつり深さを判定するためにコンクリート構造物の深さ方向についてコンクリートの圧縮強度が低下している範囲を調査する必要がある場合がある。この場合、直接的にコンクリートの圧縮強度を測定することも考えられるが、コンクリート構造物から多数のコアを採取し、採取したコアから深さの異なる多数の供試体を切り出して圧縮強度試験を行う必要があり、コンクリート構造物に多数の穴が残るという問題がある。 By the way, for example, when the surface of a concrete structure damaged by a fire is repaired or reinforced, the compressive strength of the concrete decreases in the depth direction of the concrete structure in order to determine the suspension depth. You may need to investigate the area you are doing. In this case, it may be possible to directly measure the compressive strength of concrete, but a large number of cores are collected from the concrete structure, and a large number of specimens with different depths are cut out from the collected cores to perform a compressive strength test. There is a problem that many holes remain in the concrete structure.
また、上述のシュミットハンマーを用いたコンクリートの圧縮強度の推定方法では、コンクリート構造物の表面の反発硬度を測定してコンクリート構造物の表面の圧縮強度を推定できるのみであり、当該推定方法は、コンクリート構造物の深さ方向の位置毎に反発硬度を測定してその位置毎にコンクリートの圧縮強度を推定できるというものではない。 Further, in the method for estimating the compressive strength of concrete using the Schmitt hammer described above, it is only possible to estimate the compressive strength of the surface of the concrete structure by measuring the rebound hardness of the surface of the concrete structure. It is not possible to measure the rebound hardness at each position in the depth direction of the concrete structure and estimate the compressive strength of the concrete at each position.
本発明は、上記事情に鑑みてなされたものであり、コンクリート構造物からの多数のコアの採取を要することなく、コンクリート構造物の深さ方向についてコンクリートの圧縮強度が低下している範囲を精度よく推定することを課題とするものである。 The present invention has been made in view of the above circumstances, and does not require the collection of a large number of cores from a concrete structure, so that the range in which the compressive strength of the concrete is reduced in the depth direction of the concrete structure is accurately measured. The problem is to estimate well.
上記課題を解決するために、本発明に係るコンクリート構造物においてコンクリートの圧縮強度が低下している範囲を推定する方法は、コンクリート構造物から深さ方向に向って反発硬度測定用のコアを抜き取る第一のコア採取工程と、前記反発硬度測定用のコアの深さ方向の位置毎にエコーチップ硬さ試験により反発硬度を測定する反発硬度測定工程と、測定した前記反発硬度の分布から、該反発硬度が一定となっている範囲を前記コンクリート構造物の健全部とみなし、該健全部の反発硬度に基づいて前記コンクリート構造物の健全部以浅における圧縮強度が低下している範囲を推定する推定工程と、を備え、前記推定工程は、前記コンクリート構造物の健全部以浅においてコアの深さ方向の測定点毎の前記反発硬度の平均値の、前記健全部の反発硬度の平均値に対する割合を算定し、該割合が、補修が必要な範囲を決定するために予め設定した所定値未満であるか否かを判定し、前記割合が所定値未満であれば、前記測定点の圧縮強度が基準値未満であると認定し、基準値未満となった測定点が含まれる範囲を、補修が必要である範囲と認定することを特徴とする。 In order to solve the above-mentioned problems, a method for estimating a range where the compressive strength of concrete is reduced in a concrete structure according to the present invention is obtained by extracting a core for measuring rebound hardness from the concrete structure in the depth direction. From the first core sampling step, the rebound hardness measurement step of measuring the rebound hardness by an echo tip hardness test for each position in the depth direction of the core for rebound hardness measurement, and the distribution of the measured rebound hardness, Estimating the range where the rebound hardness is constant as the sound part of the concrete structure, and estimating the range where the compressive strength of the concrete structure is lower than the sound part based on the rebound hardness of the sound part comprising a step, wherein the estimation step, the average value of the repulsive hardness of each measurement point in the depth direction of the core in the healthy section shallower of the concrete structure, said Ken The ratio of the average rebound hardness of the part is calculated, it is determined whether or not the ratio is less than a predetermined value set in advance to determine the range that needs repair, and the ratio is less than the predetermined value. For example, it is recognized that the compression strength of the measurement point is less than a reference value, and a range including the measurement point that is less than the reference value is recognized as a range requiring repair .
また、コンクリート構造物から深さ方向に向って反発硬度測定用のコアを抜き取る第一のコア採取工程と、前記反発硬度測定用のコアの深さ方向の位置毎にエコーチップ硬さ試験により反発硬度を測定する反発硬度測定工程と、測定した前記反発硬度の分布から、該反発硬度が一定となっている範囲を前記コンクリート構造物の健全部とみなし、該健全部の反発硬度に基づいて前記コンクリート構造物の健全部以浅における圧縮強度が低下している範囲を推定する推定工程と、前記コンクリート構造物から深さ方向に向って圧縮強度試験用のコアを抜き取る第二のコア採取工程と、前記圧縮強度試験用のコアにおける前記健全部について圧縮強度試験を実施する圧縮強度試験工程と、を備え、前記推定工程では、前記健全部の前記圧縮強度の測定値と、前記健全部の反発硬度および前記健全部以浅における各測定点の反発硬度に基づいて、前記健全部以浅における各測定点の圧縮強度を算出し、該健全部以浅の各測定点の圧縮強度が、補修が必要な範囲を決定するために予め設定した所定値未満であるか否かを判定し、該健全部以浅の各測定点の圧縮強度が所定値未満であれば、前記測定点の圧縮強度が基準値未満であると認定し、該健全部以浅の、圧縮強度が基準値未満となった測定点が含まれる範囲を、補修が必要である範囲と認定することにより、前記健全部以浅における圧縮強度を算出してもよい。
In addition, a first core collecting step for extracting the core for measuring the rebound hardness from the concrete structure in the depth direction, and a rebound by echo chip hardness test for each position in the depth direction of the core for measuring the rebound hardness. From the rebound hardness measurement step of measuring the hardness and the distribution of the measured rebound hardness, the range in which the rebound hardness is constant is regarded as a healthy part of the concrete structure, and the rebound hardness based on the rebound hardness of the sound part An estimation step for estimating a range in which the compressive strength in the shallow part of the concrete structure is reduced, and a second core sampling step for extracting a core for a compressive strength test in the depth direction from the concrete structure; A compressive strength test step of performing a compressive strength test on the healthy portion in the core for compressive strength test, and in the estimating step, the compressive strength of the healthy portion Based on the fixed value, the rebound hardness of the healthy part and the rebound hardness of each measurement point shallower than the healthy part, the compression strength of each measurement point shallower than the healthy part is calculated, and the compression of each measurement point shallower than the healthy part It is determined whether the strength is less than a predetermined value set in advance in order to determine a range that requires repair, and if the compression strength of each measurement point shallower than the healthy part is less than a predetermined value, the measurement point By certifying that the compressive strength is less than the standard value and including a measurement point that is shallower than the healthy part and the compressive strength is less than the standard value as a range that requires repair, You may calculate the compressive strength in the shallow part.
本発明によれば、コンクリート構造物からの多数のコアの採取を要することなく、コンクリート構造物の深さ方向についてコンクリートの圧縮強度が低下している範囲を精度よく推定することができる。 According to the present invention, it is possible to accurately estimate the range in which the compressive strength of the concrete is reduced in the depth direction of the concrete structure without requiring the collection of many cores from the concrete structure.
以下、本発明の一実施形態を、図面を参照しながら説明する。図1は、加熱によりコンクリートの圧縮強度が低下した範囲を推定する方法について、実験的に検証する手順を示すフローチャートである。このフローチャートに示すように、まず、ＲＡＢＴ（ドイツ交通省、道路・トンネルの設備と運用に関する指針）で規定された曲線（以下、ＲＡＢＴ曲線）による加熱条件（１２００℃、６０分）でコンクリートの試験体を加熱する（ステップ１）。この試験体は厚さ５００ｍｍであり、この試験体の幅９００ｍｍ、高さ１３００ｍｍの範囲を加熱した。試験体に用いたコンクリートの種類、水セメント比は、高炉セメントＢ種、３５％とした。 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing a procedure for experimentally verifying a method for estimating a range in which the compressive strength of concrete has decreased due to heating. As shown in this flow chart, first, concrete tests were conducted under heating conditions (1200 ° C, 60 minutes) according to a curve (hereinafter referred to as RABT curve) defined by RABT (German Transport Ministry, Guidelines for Road and Tunnel Equipment and Operation). The body is heated (step 1). This test body was 500 mm in thickness, and the range of 900 mm in width and 1300 mm in height was heated. The type of concrete used for the test body and the water-cement ratio were blast furnace cement type B and 35%.
試験体の加熱時には、コンクリート内部の温度履歴を測定し、コンクリートの加熱面からの深さ方向についての最高温度の分布を得た（図２参照）。なお、試験体にポリプロピレン短繊維を混入することにより、加熱による試験体の爆裂を防止した。 During the heating of the specimen, the temperature history inside the concrete was measured, and the maximum temperature distribution in the depth direction from the heated surface of the concrete was obtained (see FIG. 2). In addition, the explosion of the test body by heating was prevented by mixing polypropylene short fiber into the test body.
次に、１本の反発硬度測定用の円柱形状のコアと、複数本の圧縮強度試験用の円柱形状のコアとを、試験体からその深さ方向に抜き取る(ステップ２)。そして、コアを断面半円形状に切断することにより、反発硬度測定用の供試体１（図３参照）を作製し、複数本のコアから、加熱面からの深さが異なる複数種類の圧縮強度試験用の供試体２を切り出す（ステップ３）。反発硬度測定用のコアの直径はφ１００ｍｍであり、圧縮強度試験用のコアの直径はφ６８ｍｍである。また、図４に示すように、供試体２は、コアの加熱面から３０、５０、７０、１００、１５０、２００および３００ｍｍの位置から所定の長さ（例えば、直径の２倍程度であり、今回は１３０ｍｍ）だけ切り出すことにより作製する。 Next, one cylindrical core for rebound hardness measurement and a plurality of cylindrical cores for compressive strength test are extracted from the test body in the depth direction (step 2). Then, the specimen 1 for rebound hardness measurement (see FIG. 3) is prepared by cutting the core into a semicircular cross section, and a plurality of types of compressive strengths having different depths from the heating surface are obtained from the plurality of cores. The test specimen 2 for testing is cut out (step 3). The diameter of the core for rebound hardness measurement is φ100 mm, and the diameter of the core for compressive strength test is φ68 mm. Moreover, as shown in FIG. 4, the specimen 2 has a predetermined length (for example, about twice the diameter) from a position of 30, 50, 70, 100, 150, 200 and 300 mm from the heating surface of the core. It is produced by cutting out only 130 mm).
次に、図３に示すように、小型の反発硬度測定器であるエコーチップ硬さ試験装置３を用いて供試体１の平面１Ａの反発硬度を測定してその分布を求める（ステップ４）。エコーチップ硬さ試験装置３は、ＥＱＵＯ原理を応用した試験装置であり、タングステンカーバイト製の球状テストチップが先端についたインパクトボディを、一定のバネの力で材料の表面に打ち付けて硬さの指標Ｌ値を求めるものである。このエコーチップ硬さ試験装置３は、測定方向に制約が無い、水平面のみならず曲面を有する供試体もアタッチメントを使うことなく測定できる、等の特徴を有しており、シュミットハンマー試験装置を用いては測定できない、コアの側面である供試体１の平面１Ａに対しても容易に適用できる。 Next, as shown in FIG. 3, the rebound hardness of the plane 1 </ b> A of the specimen 1 is measured using an echo tip hardness tester 3 which is a small rebound hardness measuring instrument, and the distribution is obtained (step 4). The Echo Tip Hardness Tester 3 is a test device applying the EQUO principle. The impact body with a tungsten carbide spherical test tip attached to the tip is struck against the surface of the material with a constant spring force. The index L value is obtained. This echo chip hardness test apparatus 3 has features such as that there is no restriction in the measurement direction, and that a specimen having a curved surface as well as a horizontal plane can be measured without using an attachment, and a Schmitt hammer test apparatus is used. It can be easily applied to the plane 1A of the specimen 1 that is the side surface of the core, which cannot be measured.
本測定では、加熱面から２００ｍｍまでは１ｃｍ間隔で、加熱面から２００ｍｍ以深は２ｃｍ間隔で土木学会基準（ＪＳＣＥ−Ｇ５０４）に準拠して測定する。また、本測定は、同一の点を連続打撃する連打法により行うところ、打撃点数は２０点とし、偏差が平均値の±２０％以上となる値があれば、その測定値に代わる測定値を補う。 In this measurement, measurement is performed in accordance with the Japan Society of Civil Engineers standard (JSCE-G504) at intervals of 1 cm from the heating surface to 200 mm and at intervals of 200 cm or more from the heating surface. In addition, this measurement is performed by the continuous hitting method in which the same point is continuously hit. When the number of hit points is 20, and there is a value whose deviation is ± 20% or more of the average value, a measured value instead of the measured value is used. compensate.
次に、ＪＩＳ Ａ １１０７「コンクリートからのコアの採取方法及び圧縮強度試験方法」に準拠して、複数種類の供試体２の圧縮強度試験を行う（ステップ５）。そして、供試体１の反発硬度と供試体２の圧縮強度の測定結果から、コンクリートの残存圧縮強度分布と反発硬度分布との相関関係を求める（ステップ６）。以下、加熱によるコンクリートの残存圧縮強度分布と反発硬度分布との相関関係を求める方法について説明する。 Next, in accordance with JIS A 1107 “Method for sampling core from concrete and compressive strength test method”, a compressive strength test is performed on plural types of specimens 2 (step 5). Then, the correlation between the residual compressive strength distribution and the rebound hardness distribution of the concrete is obtained from the measurement results of the rebound hardness of the specimen 1 and the compressive strength of the specimen 2 (step 6). Hereinafter, a method for obtaining the correlation between the residual compressive strength distribution and the rebound hardness distribution of the concrete by heating will be described.
図５は、供試体１の反発硬度と供試体２の圧縮強度の測定結果を示す表である。この表に示すように、供試体１の反発硬度と供試体２の圧縮強度とは共に、加熱面近傍の測定値には多少のばらつきが見られるものの、加熱面近傍では平均すると加熱面からの深さが小さくなるほど、測定値が減少する傾向が認められた。 FIG. 5 is a table showing the measurement results of the rebound hardness of the specimen 1 and the compressive strength of the specimen 2. As shown in this table, both the rebound hardness of the specimen 1 and the compressive strength of the specimen 2 show some variation in the measured values in the vicinity of the heating surface. There was a tendency for the measured value to decrease as the depth decreased.
図６は、２０℃のコンクリートの圧縮強度に対する各温度でのコンクリートの圧縮強度の比をまとめたグラフである。このグラフは、トンネル構造設計要領（シールド工法編）「第３編 耐火設計」（首都高速道路株式会社発行、ｐ１１−１２）から抜粋したものである。このグラフで示す２０℃のコンクリートの圧縮強度に対する各温度でのコンクリートの圧縮強度の比と、図２に示すコンクリートの加熱面からの深さ方向についての最高温度分布とから、コンクリートの残存圧縮強度分布を推定し、その推定値を図７のグラフに示している。 FIG. 6 is a graph summarizing the ratio of the compressive strength of concrete at each temperature to the compressive strength of concrete at 20 ° C. This graph is excerpted from the tunnel structure design guideline (shield construction method) “Part 3 Fireproof Design” (issued by Metropolitan Expressway Co., Ltd., p. 11-12). From the ratio of the compressive strength of the concrete at each temperature to the compressive strength of the concrete at 20 ° C. shown in this graph and the maximum temperature distribution in the depth direction from the heating surface of the concrete shown in FIG. The distribution is estimated, and the estimated value is shown in the graph of FIG.
図７は、上記推定値と、反発硬度及び圧縮強度の健全部に対する割合とを示すグラフである。ここで、健全部とは、加熱によるコンクリートの圧縮強度に対する影響が小さい加熱面から１５０ｍｍ以深の部位のことを指し、反発硬度及び圧縮強度の健全部に対する割合とは、それぞれの深さでの反発硬度及び圧縮強度を、健全部の測定値の平均値で除して無次元化した値である。 FIG. 7 is a graph showing the estimated value and the ratio of the rebound hardness and the compressive strength to the healthy part. Here, the healthy part refers to a part deeper than 150 mm from the heating surface, which has a small influence on the compressive strength of the concrete by heating, and the ratio of the rebound hardness and the compressive strength to the healthy part is the repulsion at each depth. It is a value obtained by dividing the hardness and compressive strength by the average value of the measured values of the healthy part and making it dimensionless.
図７のグラフに示すように、加熱されたコンクリートの深さ方向に測定した反発硬度の健全部の反発硬度に対する割合の分布と、加熱されたコンクリートの深さ方向に測定した圧縮強度の健全部の圧縮強度に対する割合との分布とはほぼ一致した。 As shown in the graph of FIG. 7, the distribution of the ratio of the rebound hardness measured in the depth direction of the heated concrete to the rebound hardness of the healthy portion and the sound strength portion of the compressive strength measured in the depth direction of the heated concrete The distribution of the ratio to the compressive strength was almost consistent.
以上説明したように、加熱されたコンクリートの深さ方向に測定した反発硬度の健全部の反発硬度に対する割合の分布と、加熱されたコンクリートの深さ方向に測定した圧縮強度の健全部の圧縮強度に対する割合との分布とはほぼ一致するという知見が得られたので、以下説明する実施例では、この知見に基づき、加熱されたコンクリートの深さ方向についてコンクリートの圧縮強度が低下している範囲を推定する。 As explained above, the distribution of the ratio of the resilience hardness measured in the depth direction of the heated concrete to the resilience hardness of the healthy portion and the compressive strength of the sound strength portion measured in the depth direction of the heated concrete Based on this finding, in the examples described below, the range in which the compressive strength of the concrete is reduced in the depth direction of the heated concrete is obtained. presume.
図８は、一実施例に係る、火災により火害を受けたトンネルの覆工コンクリートの深さ方向について圧縮強度が低下している範囲を推定する手順を示すフローチャートである。このフローチャートに示すように、まず、１本の反発硬度測定用の円柱形状のコアを、覆工コンクリートからその深さ方向に抜き取る(ステップ１１)。次に、コアを断面半円形状に切断することにより、反発硬度測定用の供試体１（図３参照）を作製する（ステップ１２）。 FIG. 8: is a flowchart which shows the procedure which estimates the range which the compressive strength has fallen about the depth direction of the lining concrete of the tunnel damaged by the fire based on one Example. As shown in this flowchart, first, one cylindrical core for measuring the rebound hardness is extracted from the lining concrete in the depth direction (step 11). Next, the core 1 is cut into a semicircular cross section to prepare a specimen 1 for rebound hardness measurement (see FIG. 3) (step 12).
次に、エコーチップ硬さ試験装置３（図３参照）を用いて供試体１の平面１Ａの反発硬度を測定し、その分布を求める（ステップ１３）。本測定では、反発硬度が一定となっている範囲を健全部（加熱面から１５０ｍｍ以深）とみなし、該健全部における一点もしくは深さが異なる複数点で連打法により測定を行って反発硬度の平均値を求め、健全部以浅における深さが異なる複数点で連打法により測定を行って各点の反発硬度の平均値を求める。 Next, the rebound hardness of the plane 1A of the specimen 1 is measured using the echo chip hardness test apparatus 3 (see FIG. 3), and the distribution is obtained (step 13). In this measurement, the range in which the rebound hardness is constant is regarded as a healthy part (150 mm or deeper from the heating surface), and the average of the rebound hardness is measured by a continuous hitting method at one point or multiple points at different depths in the healthy part. The value is obtained, and the average value of the rebound hardness at each point is obtained by performing measurement by a repeated hitting method at a plurality of points having different depths in the shallower part than the healthy part.
次に、健全部以浅の各点の反発硬度の平均値を、健全部の測定値の平均値で除して、健全部以浅の各点の反発硬度の、健全部の反発硬度に対する割合を求める（ステップ１４）。そして、健全部以浅の各点の反発硬度の、健全部における反発硬度に対する割合が、補修が必要な範囲を決定するために予め設定した所定値（例えば、０．８）未満であるか否かを判定し（ステップ１５）、当該割合が所定値未満であれば、当該測定点における残存圧縮強度が基準値未満であると認定し（ステップ１６）、当該割合が所定以上であれば、当該測定点における残存圧縮強度が基準値以上であると認定する（ステップ１７）。最後に、上記割合が基準値未満となった測定点が含まれる範囲を、補修が必要である範囲と認定する（ステップ１８）。 Next, the average value of the rebound hardness at each point shallower than the healthy part is divided by the average value of the measured value at the healthy part to determine the ratio of the rebound hardness at each point shallower than the healthy part to the rebound hardness of the healthy part. (Step 14). Whether or not the ratio of the rebound hardness at each point shallower than the healthy part to the rebound hardness at the healthy part is less than a predetermined value (for example, 0.8) set in advance in order to determine a range that requires repair. (Step 15), if the ratio is less than a predetermined value, it is determined that the residual compressive strength at the measurement point is less than a reference value (step 16). It is recognized that the residual compressive strength at the point is equal to or higher than the reference value (step 17). Finally, the range including the measurement points where the ratio is less than the reference value is recognized as a range requiring repair (step 18).
以上により、多数のコアを覆工コンクリートから採取することなく、トンネルの覆工コンクリートの深さ方向について圧縮強度が低下している範囲を精度よく推定することができ、補修が必要な範囲を精度よく認定することができる。 As described above, it is possible to accurately estimate the range where the compressive strength is reduced in the depth direction of the lining concrete of the tunnel without collecting a large number of cores from the lining concrete, and to accurately determine the range that needs repair. Can be certified well.
図９は、他の実施例に係る、火災により火害を受けたトンネルの覆工コンクリートの深さ方向について圧縮強度が低下している範囲を推定する手順を示すフローチャートである。このフローチャートに示すように、まず、１本の反発硬度測定用の円柱形状のコアと、１本の圧縮強度試験用の円柱形状のコアとを、覆工コンクリートからその深さ方向に抜き取る(ステップ２１)。そして、反発硬度測定用のコアを断面半円形状に切断することにより、反発硬度測定用の供試体１（図３参照）を作製する（ステップ２２）。 FIG. 9: is a flowchart which shows the procedure which estimates the range which the compressive strength has fallen about the depth direction of the lining concrete of the tunnel which received the fire damage according to the other Example. As shown in this flowchart, first, one cylindrical core for rebound hardness measurement and one cylindrical core for compressive strength test are extracted from the lining concrete in the depth direction (steps). 21). Then, the specimen for rebound hardness measurement 1 (see FIG. 3) is manufactured by cutting the core for rebound hardness measurement into a semicircular cross section (step 22).
次に、エコーチップ硬さ試験装置３（図３参照）を用いて供試体１の平面１Ａの反発硬度を測定し、その分布を求める工程を、上述の実施例のステップ１３と同様に実施する（ステップ２３）。そして、反発硬度が一定の範囲を健全部（１５０ｍｍ以深）とみなし、健全部から所定長さ切り出すことにより圧縮強度試験用のコアを作製する（ステップ２４）。次に、ＪＩＳ Ａ １１０７「コンクリートからのコアの採取方法及び圧縮強度試験方法」に準拠して、供試体２の圧縮強度試験を行う（ステップ２５）。 Next, the step of measuring the rebound hardness of the plane 1A of the specimen 1 using the echo chip hardness test apparatus 3 (see FIG. 3) and obtaining the distribution is carried out in the same manner as step 13 of the above-described embodiment. (Step 23). Then, a range in which the rebound hardness is constant is regarded as a sound part (150 mm or deeper), and a core for a compressive strength test is produced by cutting out a predetermined length from the sound part (step 24). Next, the compressive strength test of the specimen 2 is performed in accordance with JIS A 1107 “Method for collecting core from concrete and test method for compressive strength” (step 25).
そして、健全部以浅の各点の反発硬度の平均値を、健全部の測定値の平均値で除して、健全部以浅の各点の反発硬度の、健全部の反発硬度に対する割合を求める（ステップ２６）。次に、供試体２の圧縮強度の測定値、即ち健全部の圧縮強度の測定値に対して、健全部以浅の各点の反発硬度の、健全部の反発硬度に対する割合を乗じることにより、健全部以浅の各点の残存圧縮強度を算出する（ステップ２７）。そして、健全部以浅の各点の残存圧縮強度が、補修が必要な範囲を決定するために予め設定した所定値未満であるか否かを判定し（ステップ２８）、所定値未満であれば、当該測定点における残存圧縮強度が基準値未満であると認定し（ステップ２９）、所定値以上であれば、当該測定点における残存圧縮強度が基準値以上であると認定する（ステップ３０）。最後に、上記残存圧縮強度が基準値未満となった測定点が含まれる範囲を、補修が必要である範囲と認定する（ステップ３１）。 Then, the average value of the rebound hardness at each point shallower than the healthy part is divided by the average value of the measured value at the healthy part to determine the ratio of the rebound hardness at each point shallower than the healthy part to the rebound hardness of the healthy part ( Step 26). Next, the measured value of the compressive strength of the specimen 2, that is, the measured compressive strength value of the healthy part, is multiplied by the ratio of the rebound hardness of each point shallower than the healthy part to the rebound hardness of the healthy part. The residual compressive strength of each point shallower than the part is calculated (step 27). And it is determined whether the residual compressive strength of each point shallower than the healthy part is less than a predetermined value set in advance in order to determine a range that requires repair (step 28). It is recognized that the residual compressive strength at the measurement point is less than the reference value (step 29). Finally, the range including the measurement point where the residual compressive strength is less than the reference value is recognized as a range requiring repair (step 31).
以上により、多数のコアを覆工コンクリートから採取することなく、トンネルの覆工コンクリートの深さ方向について圧縮強度が低下している範囲を精度よく推定することができ、補修が必要な範囲を精度よく認定することができる。 As described above, it is possible to accurately estimate the range where the compressive strength is reduced in the depth direction of the lining concrete of the tunnel without collecting a large number of cores from the lining concrete, and to accurately determine the range that needs repair. Can be certified well.
なお、上述の実施形態は、本発明の理解を容易にするためのものであり、本発明を限定するものではない。本発明はその趣旨を逸脱することなく、変更、改良され得ると共に本発明にはその等価物が含まれることは勿論である。例えば、上述の実施形態では、加熱されたコンクリート構造物におけるコンクリートの圧縮強度が低下した範囲を推定する方法を例に挙げて本発明を説明したが、コンクリートの圧縮強度が化学的腐食等の要因により低下した場合にも本発明を適用することができる。 In addition, the above-mentioned embodiment is for making an understanding of this invention easy, and does not limit this invention. It goes without saying that the present invention can be changed and improved without departing from the gist thereof, and that the present invention includes equivalents thereof. For example, in the above-described embodiment, the present invention has been described by taking as an example a method for estimating the range in which the compressive strength of concrete in a heated concrete structure has decreased. However, the compressive strength of concrete is a factor such as chemical corrosion. The present invention can also be applied to a case where the voltage drops due to the above.
また、上述の実施形態では、採取したコアを断面半円形状に切断してから反発硬度を測定したが、断面半円形状に限らず、コア外周の一部が平面となるように切断してその平面の反発硬度を測定してもよいし、切断することなしにコア外周の曲面の反発硬度を測定してもよい。 Further, in the above-described embodiment, the rebound hardness was measured after cutting the collected core into a semicircular cross section. However, the rebound hardness is not limited to the semicircular cross section, and the core is cut so that a part of the outer periphery becomes a flat surface. The rebound hardness of the plane may be measured, or the rebound hardness of the curved surface around the core may be measured without cutting.
さらに、上述の実施形態では、加熱されたコンクリートの深さ方向に測定した反発硬度の分布に基づいて健全部を推定し、その健全部の反発硬度に対する反発硬度の割合の分布に基づいて、コンクリートの圧縮強度が低下している範囲を推定した。しかし、加熱されたコンクリートの深さ方向に測定した反発硬度の分布に基づいて健全部を推定せずに、測定した反発硬度の分布のみに基づいて、コンクリートの圧縮強度が低下している範囲を推定してもよい。 Furthermore, in the above-described embodiment, the healthy part is estimated based on the distribution of the rebound hardness measured in the depth direction of the heated concrete, and based on the distribution of the ratio of the rebound hardness to the rebound hardness of the healthy part, the concrete The range in which the compressive strength was reduced was estimated. However, without estimating the healthy part based on the distribution of the rebound hardness measured in the depth direction of the heated concrete, the range in which the compressive strength of the concrete is reduced based only on the distribution of the rebound hardness measured. It may be estimated.
１、２ 供試体、３ エコーチップ硬さ試験装置 1, 2 Specimen, 3 Echo chip hardness tester
Claims (2)
前記反発硬度測定用のコアの深さ方向の位置毎にエコーチップ硬さ試験により反発硬度を測定する反発硬度測定工程と、
測定した前記反発硬度の分布から、該反発硬度が一定となっている範囲を前記コンクリート構造物の健全部とみなし、該健全部の反発硬度に基づいて前記コンクリート構造物の健全部以浅における圧縮強度が低下している範囲を推定する推定工程と、を備え、
前記推定工程は、
前記コンクリート構造物の健全部以浅においてコアの深さ方向の測定点毎の前記反発硬度の平均値の、前記健全部の反発硬度の平均値に対する割合を算定し、
該割合が、補修が必要な範囲を決定するために予め設定した所定値未満であるか否かを判定し、
前記割合が所定値未満であれば、前記測定点の圧縮強度が基準値未満であると認定し、基準値未満となった測定点が含まれる範囲を、補修が必要である範囲と認定することを特徴とするコンクリート構造物においてコンクリートの圧縮強度が低下している範囲を推定する方法。 A first core collecting step of extracting a core for rebound hardness measurement from the concrete structure in the depth direction;
A rebound hardness measurement step of measuring the rebound hardness by an echo tip hardness test for each position in the depth direction of the core for rebound hardness measurement;
From the measured rebound hardness distribution, the range where the rebound hardness is constant is regarded as the sound part of the concrete structure, and the compressive strength of the concrete structure is shallower than the sound part based on the rebound hardness of the sound part. An estimation step for estimating a range in which
The estimation step includes
Calculate the ratio of the average value of the rebound hardness at each measurement point in the depth direction of the core in the shallow part of the concrete structure to the average value of the rebound hardness of the sound part,
It is determined whether or not the ratio is less than a predetermined value set in advance to determine a range that requires repair,
If the ratio is less than a predetermined value, the compression strength of the measurement point is recognized as being less than the reference value, and the range including the measurement point that is less than the reference value is recognized as a range that requires repair. A method for estimating the extent to which the compressive strength of concrete is reduced in a concrete structure characterized by the above.
前記反発硬度測定用のコアの深さ方向の位置毎にエコーチップ硬さ試験により反発硬度を測定する反発硬度測定工程と、
測定した前記反発硬度の分布から、該反発硬度が一定となっている範囲を前記コンクリート構造物の健全部とみなし、該健全部の反発硬度に基づいて前記コンクリート構造物の健全部以浅における圧縮強度が低下している範囲を推定する推定工程と、
前記コンクリート構造物から深さ方向に向って圧縮強度試験用のコアを抜き取る第二のコア採取工程と、
前記圧縮強度試験用のコアにおける前記健全部について圧縮強度試験を実施する圧縮強度試験工程と、を備え、
前記推定工程では、
前記健全部の前記圧縮強度の測定値と、前記健全部の反発硬度および前記健全部以浅における各測定点の反発硬度に基づいて、前記健全部以浅における各測定点の圧縮強度を算出し、
該健全部以浅の各測定点の圧縮強度が、補修が必要な範囲を決定するために予め設定した所定値未満であるか否かを判定し、
該健全部以浅の各測定点の圧縮強度が所定値未満であれば、前記測定点の圧縮強度が基準値未満であると認定し、該健全部以浅の、圧縮強度が基準値未満となった測定点が含まれる範囲を、補修が必要である範囲と認定することを特徴とするコンクリート構造物においてコンクリートの圧縮強度が低下している範囲を推定する方法。 A first core collecting step of extracting a core for rebound hardness measurement from the concrete structure in the depth direction;
A rebound hardness measurement step of measuring the rebound hardness by an echo tip hardness test for each position in the depth direction of the core for rebound hardness measurement;
From the measured rebound hardness distribution, the range where the rebound hardness is constant is regarded as the sound part of the concrete structure, and the compressive strength of the concrete structure is shallower than the sound part based on the rebound hardness of the sound part. An estimation process for estimating a range where the
A second core collecting step of extracting the core for compressive strength test from the concrete structure in the depth direction;
A compressive strength test step for performing a compressive strength test on the healthy part in the core for compressive strength test, and
In the estimation step,
Based on the measurement value of the compressive strength of the healthy part, the rebound hardness of the healthy part and the rebound hardness of each measurement point shallower than the healthy part, calculate the compressive strength of each measurement point shallower than the healthy part,
It is determined whether the compressive strength of each measurement point shallower than the healthy part is less than a predetermined value set in advance in order to determine a range that requires repair,
If the compressive strength of each measurement point shallower than the healthy part is less than a predetermined value, the compressive strength of the measurement point is recognized as less than a reference value, and the compressive strength shallower than the healthy part is less than the reference value. A method for estimating a range in which the compressive strength of concrete is reduced in a concrete structure characterized in that a range including measurement points is recognized as a range requiring repair .
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