本文關(guān)鍵詞： 抗壓強(qiáng)度 抗拉強(qiáng)度 孔隙水壓 最大粒徑 損傷值　出處：《西北農(nóng)林科技大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：混凝土強(qiáng)度與其含水量直接相關(guān)，并與其加載速率有關(guān)。該文混凝土試樣浸泡在水中讓其自由吸水，形成不同的含水量試樣，采用不同的加載速率測(cè)試其強(qiáng)度，并采用超聲波儀測(cè)定其波速，研究含水量對(duì)混凝土強(qiáng)度影響規(guī)律。另外，結(jié)合高壩混凝土在水中工作的環(huán)境，通過對(duì)混凝土標(biāo)準(zhǔn)試塊外圍施加高壓水，形成滲透作用，重點(diǎn)研究孔隙水壓、不同作用時(shí)間、不同最大骨料粒徑對(duì)C15和C20等級(jí)混凝土的力學(xué)特性影響，，以揭示高滲透孔隙水在混凝土內(nèi)滲透過程對(duì)混凝土強(qiáng)度的影響規(guī)律，得出以下結(jié)論： （1）混凝土含水量隨著其浸泡時(shí)間的增加而逐漸遞增，浸泡初期混凝土含水量增加迅速，而后逐漸放緩，并趨于穩(wěn)定，穩(wěn)定含水率在3.9%左右。混凝土試塊浸泡后其超聲波波速較浸泡前增大，超聲波穿透混凝土試件橫截面所需時(shí)間變短。當(dāng)含水量低于3.5%時(shí)，超聲波波速增加幅度不顯著，當(dāng)含水量超過3.5%時(shí)，超聲波波速增加率明顯增大。 （2）相同含水量條件下，混凝土抗壓強(qiáng)度隨加載速率的增加出現(xiàn)先迅速增大后逐漸穩(wěn)定現(xiàn)象；相同加載速率下，混凝土抗壓強(qiáng)度隨含水量增加而逐漸降低。當(dāng)加載速率大于1.0MPa/s，混凝土抗壓強(qiáng)度基本達(dá)到穩(wěn)定。混凝土抗拉強(qiáng)度隨加載速率變化趨勢(shì)與其抗壓強(qiáng)度基本相似。 （3）在壓力水作用下，隨孔隙水壓逐漸增大，混凝土抗壓強(qiáng)度損傷值呈逐漸遞增趨勢(shì)。相同孔隙水壓作用下，混凝土強(qiáng)度等級(jí)越低，其損傷值越大，最大粒徑越大，其損傷值也越大。混凝土劈裂抗拉強(qiáng)度損傷值隨著孔隙水壓的增加呈遞增趨勢(shì)，且其抗拉強(qiáng)度損傷值受混凝土強(qiáng)度等級(jí)的影響，在相同的外圍孔隙水壓力作用下混凝土強(qiáng)度等級(jí)越高，其抗拉強(qiáng)度損傷值越小。
[Abstract]:The strength of concrete is directly related to its water content and its loading rate. The influence of water content on the strength of concrete is studied by using ultrasonic wave velocity. In addition, combined with the environment of high dam concrete working in water, high pressure water is applied to the outside of concrete standard test block to form permeation effect. The effects of pore water pressure, different acting time and different maximum aggregate particle size on the mechanical properties of C15 and C20 grade concrete are studied in order to reveal the influence of high permeability pore water on the strength of concrete. Draw the following conclusions:. 1) the water content of concrete increases gradually with the increase of soaking time, and the moisture content of concrete increases rapidly at the beginning of soaking, then slows down and tends to be stable. The steady moisture content is about 3.9%. The ultrasonic wave velocity of concrete specimen increases after soaking, and the time required for ultrasonic wave penetrating the cross section of concrete specimen becomes shorter. When the water content is lower than 3.5, the ultrasonic wave velocity increase is not significant. When the water content exceeds 3.5, the increase rate of ultrasonic wave velocity increases obviously. (2) under the same water content, the compressive strength of concrete increases rapidly first and then stabilizes with the increase of loading rate, while at the same loading rate, the compressive strength of concrete increases rapidly and then stabilizes gradually with the increase of loading rate. The compressive strength of concrete decreases gradually with the increase of water content. When the loading rate is more than 1.0 MPA / s, the compressive strength of concrete is basically stable, and the variation trend of concrete tensile strength with loading rate is basically similar to its compressive strength. 3) under the action of pressure-water, with the increase of pore water pressure, the damage value of concrete compressive strength increases gradually. Under the same pore water pressure, the lower the strength grade of concrete is, the greater the damage value is and the larger the maximum particle size is. With the increase of pore water pressure, the damage value of concrete splitting tensile strength is increased with the increase of pore water pressure, and the damage value of its tensile strength is affected by the strength grade of concrete. The higher the strength grade of concrete is under the same external pore water pressure, the smaller the damage value of tensile strength is.
【學(xué)位授予單位】：西北農(nóng)林科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU528

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