基于线性回归的大坝混凝土起裂韧度确定方法  

Determination method for initial fracture toughness of dam concrete using linear regression

作　　者：卿龙邦[1] 聂雅彤 刘宁[2] 管俊峰[3] 

机构地区：[1]河北工业大学土木与交通学院,天津300401 [2]北京交通大学土木建筑工程学院,北京100044 [3]华北水利水电大学土木与交通学院,郑州450011

出　　处：《水力发电学报》2016年第8期25-31,共7页Journal of Hydroelectric Engineering

基　　金：国家自然科学基金(51309073);清华大学水沙科学与水利水电工程国家重点实验室开放基金(sklhse-2014-C-02);高等学校博士学科点专项科研基金(20131317120012);河北省自然科学基金(E2014202257);河北省高等学校科学技术研究重点项目(ZD2015028)

摘　　要：基于线性回归理论,研究了混凝土起裂韧度的简化确定方法,该方法利用混凝土断裂试验中的裂缝开裂前荷载-裂缝口张开位移(P–Δ)曲线呈线性的特点,结合线性相关系数陡降法获得起裂荷载,进而求得起裂韧度。利用现有最大骨料粒径分别为150 mm的大坝混凝土楔入劈拉试验以及80 mm和40 mm的三点弯曲梁试验对本文方法进行了验证。本方法避开了传统需要粘贴应变片测量起裂荷载的方法,可以较准确地得到混凝土起裂韧度。相比于其他计算方法,操作简便,受人为因素影响小,无须进行复杂的运算。另外,采用本文方法研究了起裂韧度的尺寸效应,结果表明,试件尺寸对起裂韧度的影响较小。A simplified method for determining the initial fracture toughness of dam concrete was examined in this study based on the linear regression theory. It determines initial cracking load using a P- A curve of load versus crack opening displacement, which is linear before cracking and takes a sudden drop in linear correlation coefficient at cracking stage. It was verified using previously reported experimental data on dam concrete of wedge-splitting specimens with aggregate sizes up to 150 mm and three-point bending specimens with aggregate sizes up to 80 and 40 mm, respectively. The new method has a higher accuracy and avoids use of strain gauges for measuring initial cracking load in the traditional method. Thus, relative to other analytical methods, it is easier to operate without complicated calculations and insensitive to artificial factors. Moreover, the method was used to examine the effect of specimen sizes on initial fracture toughness, showing its insignificance in application.

关 键 词：混凝土 裂缝 起裂韧度 起裂荷载 线性回归 

分 类 号：TV313[水利工程—水工结构工程] TU528.36[建筑科学—建筑技术科学]