【摘要】：鉆芯法作為檢測(cè)混凝土抗壓強(qiáng)度的直接方法被廣泛應(yīng)用。隨著實(shí)際工作對(duì)檢測(cè)要求的提高，現(xiàn)有鉆芯技術(shù)已不能完全滿足需要。本文針對(duì)比目前允許使用的直徑70mm芯樣更小的直徑為50mm的超小芯樣展開研究，用于解決實(shí)際問題。 目前對(duì)直徑為50mm的超小芯樣應(yīng)用上的主要障礙是小芯樣的尺寸效應(yīng)及離散性問題。本文分析了國(guó)內(nèi)外大量的研究資料并制作了522個(gè)芯樣進(jìn)行不同直徑芯樣間的強(qiáng)度比對(duì)。可以看出芯樣不同于澆筑成型的立方體試塊，受多種因素的影響，一般不隨直徑的減小而增大，尺寸效應(yīng)沒有澆筑成型的試塊明顯。芯樣直徑與粗骨料最大粒徑之比及粗骨料被切割的位置對(duì)抗壓強(qiáng)度有較大影響，混凝土芯樣與粗骨料最大粒徑之比宜大于等于2。高徑比不同體現(xiàn)出來的尺寸效應(yīng)對(duì)混凝土抗壓強(qiáng)度的影響更顯著，故不建議采用短芯樣來評(píng)定薄構(gòu)件。鉆芯法檢測(cè)結(jié)果的不確定性源于系統(tǒng)、隨機(jī)和檢測(cè)操作三個(gè)方面。鉆芯法檢測(cè)混凝土強(qiáng)度的系統(tǒng)偏差較�。粰z測(cè)操作過程中的偏差會(huì)對(duì)芯樣強(qiáng)度值降低，對(duì)小芯樣的影響將更為顯著應(yīng)嚴(yán)格控制，對(duì)于50mm直徑超小芯樣不宜含有鋼筋。泵送混凝土和噴射混凝土粗骨料最大粒徑可得到控制，混凝土勻質(zhì)性較好，可減小樣本的離散性，符合超小芯樣的研究條件。 泵送和噴射混凝土50mm小芯樣抗壓強(qiáng)度值服從正態(tài)分布，可以運(yùn)用統(tǒng)計(jì)學(xué)中的知識(shí)進(jìn)行分析統(tǒng)計(jì)。通過統(tǒng)計(jì)學(xué)中顯著性假設(shè)檢驗(yàn)，泵送混凝土抗壓強(qiáng)度用50mm小芯樣測(cè)得的平均值與用標(biāo)準(zhǔn)試件測(cè)得的平均值沒有顯著差異，而噴射混凝土則存在顯著差異，但同時(shí)噴射混凝土50mm小芯樣與100mm直徑芯樣測(cè)得的抗壓強(qiáng)度存在顯著相關(guān)性�？烧J(rèn)為泵送混凝土50mm小芯樣與標(biāo)準(zhǔn)試件抗壓強(qiáng)度平均值基本相當(dāng)，，噴射混凝土可采取0.9的換算系數(shù)。因50mm小芯樣受各種因素干擾更明顯，離散性偏大，在小樣本的情況下，不建議采用50mm的芯樣按最小值法進(jìn)行單個(gè)評(píng)定。根據(jù)試驗(yàn)數(shù)據(jù)計(jì)算并結(jié)合工程實(shí)體取樣的客觀條件，50mm直徑超小芯樣批量檢測(cè)的取樣數(shù)量可定為：當(dāng)設(shè)計(jì)等級(jí)不大于C50時(shí)，批量檢測(cè)數(shù)量不少于25個(gè)；當(dāng)設(shè)計(jì)等級(jí)大于C50時(shí)，批量檢測(cè)數(shù)量不少于20個(gè)。
[Abstract]:The core drilling method is widely used as a direct method to measure the compressive strength of concrete. With the improvement of testing requirements, the existing core drilling technology can not fully meet the needs. In this paper, the ultra-small core sample with a diameter of 50mm that is smaller than the diameter 70mm core sample which is allowed to be used at present is studied to solve the practical problem. At present, the main obstacle in the application of ultra-small core sample with diameter 50mm is the size effect and dispersion of small core sample. In this paper, a large number of research data at home and abroad were analyzed and 522 core samples were made to compare the strength of different diameter core samples. It can be seen that the core sample is different from the cube sample in pouring molding, which is affected by many factors, and generally does not increase with the decrease of diameter, and the size effect is not obvious. The ratio of the diameter of core to the maximum diameter of coarse aggregate and the position where coarse aggregate is cut have great influence on the compressive strength. The ratio of the maximum diameter of concrete core to coarse aggregate should be greater than or equal to 2. The dimension effect of different aspect ratio is more significant to the compressive strength of concrete, so it is not recommended to use the short core sample to evaluate the thin members. The uncertainty of the test result of drilling core method originates from three aspects: system, random and test operation. The system deviation of testing concrete strength by drilling core method is small, and the deviation during testing operation will decrease the strength value of the core sample, and the influence on the small core sample should be strictly controlled, and the reinforcement should not be included in the ultra-small core sample of 50mm diameter. The maximum particle size of pumping concrete and shotcrete coarse aggregate can be controlled, the homogeneity of concrete is better, the dispersion of samples can be reduced, and the research conditions of ultra-small core samples are satisfied. The compressive strength of pumping and shotcrete 50mm core samples is normally distributed and can be analyzed by using the knowledge of statistics. Through statistical significance hypothesis test, the average value of compressive strength of pumping concrete measured by 50mm small core sample is not significantly different from that of standard specimen, but there is significant difference between shotcrete. But there is a significant correlation between the compressive strength of shotcrete 50mm core sample and 100mm diameter core sample. It can be considered that the average compressive strength of pumping concrete 50mm core sample is basically equal to that of standard specimen, and the conversion coefficient of shotcrete can be taken as 0.9. Because the small core sample of 50mm is more obviously disturbed by various factors, the dispersion is larger. In the case of small sample, it is not recommended that the core sample of 50mm be evaluated by the method of minimum value. According to the test data and the objective conditions of engineering solid sampling, the sampling quantity of 50mm diameter ultra small core sample can be determined as: when the design grade is not greater than C50, the number of batch detection is not less than 25, and when the design grade is greater than C50, the quantity of batch detection is not less than 25, when the design grade is greater than C50, The quantity of batch inspection is not less than 20.
【學(xué)位授予單位】：清華大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU528.07

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 王安坤,周燕;混凝土短芯樣強(qiáng)度修正系數(shù)的探討[J];工程質(zhì)量;2004年12期

2 金維芬;李為杜;;鉆芯法檢測(cè)結(jié)構(gòu)混凝土的抗壓強(qiáng)度[J];工程質(zhì)量;2007年19期

3 楊在富;鉆芯法檢測(cè)混凝土強(qiáng)度的試驗(yàn)研究[J];廣西城鎮(zhèn)建設(shè);2004年05期

4 勞毅;;施工現(xiàn)場(chǎng)混凝土強(qiáng)度檢測(cè)方法的試驗(yàn)研究[J];廣西工學(xué)院學(xué)報(bào);2008年03期

5 張明軒;框架結(jié)構(gòu)外觀缺陷和尺寸偏差的統(tǒng)計(jì)分析[J];工程質(zhì)量;2004年05期

6 王文明;羅敏;;對(duì)CECS 03:2007《鉆芯法檢測(cè)混凝土強(qiáng)度技術(shù)規(guī)程》有關(guān)問題的商榷[J];混凝土;2009年04期

7 劉紅義;張勁泉;程壽山;和海芳;;混凝土芯樣抗壓強(qiáng)度尺寸效應(yīng)研究[J];混凝土;2012年02期

8 曹艷冰;楊曉峰;賈非;;不同直徑芯樣所測(cè)混凝土抗壓強(qiáng)度關(guān)系的研究[J];山西建筑;2008年09期

9 張立軍,安明U

本文編號(hào)：2283878