【摘要】 通过对4组10 cm×10 cm×40 cm混凝土试件的快速冻融循环试验,以及采用共振法和超声法进行试件的波速和频率测试,得到了冻融循环200次混凝土试件的损伤参量特征值和强度变化规律,论证了超声波速作为损伤参量测试值的合理性,研究了冻融循环对纤维混凝土材料损伤特性的影响因素,分析了纤维混凝土冻融损伤破坏的细观机理,结合动弹性模量和超声波速相对值的变化特点,根据细观损伤力学和数学模拟的方法建立了纤维混凝土冻融损伤本构模型。研究分析和测试计算显示:纤维混凝土冻融损伤模型的计算值与实测值基本吻合,本构模型预测的混凝土损伤特性符合混凝土实际冻融破坏情况;超声波速作为损伤参量易于测量且易与宏观量建立联系,能够较好地反应纤维混凝土冻融损伤规律;聚丙烯纤维在混凝土中能够产生引气效应,可有效地抑制混凝土的冻融损伤劣化程度,在本文研究的混凝土强度范围内纤维掺量为10%时混凝土抗冻性最好。更多还原

【Abstract】 Through rapid freeze-thaw cycle experiment on 4 groups of 10cm×10cm×40cm concrete samples,along with using resonates and supersonic method to test the wave velocity and frequency of the samples,the damage parameter characteristic value and the intensity change of concrete samples after 200 freeze-thaw cycles were obtained.The rationality of supersonic wave velocity as damage parameter test value has been proved;the influencing factors of freeze-thaw cycle on the fiber reinforced concrete material damage characteristic have been studied and microscopic mechanism of damage from freeze-thaw on fiber reinforced concrete was analyzed.In addition,combined with the change characteristics of dynamic modulus and the supersonic wave velocity relative value,a fiber reinforced concrete freeze-thaw damage constitutive model was established based on methods from microscopic damage mechanics and mathematical simulation.Research and calculation indicate that calculated value from fiber reinforced concrete freeze-thaw damage model is consistent with the test value,the anticipated damage characteristic from constitutive model is consistent with the measured freeze-damage result of concrete as well,the supersonic wave velocity as the damage parameter is easy to survey and to establish relation with the macroscopic quantity and is able to reflect fiber reinforced concrete′s law of freeze-thaw damage,polypropylene fiber can cause the bleed air effect in concrete and restrain the freeze-thaw damage deterioration degree effectively.In this study,frost-resisting properties are the best when mixed with 10% fiber.更多还原