基于单缝法的混凝土工作应力微损测试  

Micro-damage test of concrete working stress using single-groove method

作　　者：顾颖 刘庭勇 彭勇军[2] 杜义祥 周子豪 古松[1] GU Ying;LIU Tingyong;PENG Yongjun;DU Yixiang;ZHOU Zihao;GU Song(School of Civil Engineering and Architecture,Southwest University of Science and Technology,Mianyang 621010,China;China Railway 18th Bureau Group Second Engineering Co.,Ltd.,Tangshan 064099,China;Sichuan Zhentong Inspection Co.,Ltd.,Mianyang 621010,China)

机构地区：[1]西南科技大学土木工程与建筑学院,四川绵阳621010 [2]中铁十八局集团第二工程有限公司,河北唐山064099 [3]四川振通检测股份有限公司,四川绵阳621010

出　　处：《铁道科学与工程学报》2024年第5期2099-2108,共10页Journal of Railway Science and Engineering

基　　金：国家自然科学基金资助项目(52108385);四川省科技计划资助项目(2022ZYDF083)。

摘　　要：混凝土工作应力是相对于无应力状态的应力增量。为准确测定混凝土工作应力,基于“应变部分释放”的理念,提出一种用于混凝土工作应力的微损伤测试方法——单缝法。该方法通过切割一条较浅的弧形狭缝来释放应力,根据测试应变来计算应力。采用数值模拟验证了单缝法的有效性,并分析了混凝土弹性模量等参数对应变释放率的影响。应变释放率为切缝释放应变与混凝土初始应变的比值。通过试验研究了应力大小、切缝深度等参数对测试精度的影响。研究结果表明:应变释放率由切缝形状与大小唯一确定,与混凝土弹性模量、应力大小、切缝宽度等参数无关;给定切缝形状与大小,就可以借助数值模拟或试验确定相应的应变释放率。释放应变沿切缝两侧呈“M”形分布,远离切缝,释放应变呈先增加、后减小的趋势。应变片应尽量布置在应变较大且单调变化的位置,故建议选用50 mm的应变片,布置在距切缝边缘25 mm的位置。切缝深度越大,切割产生的扰动应变越大,当切缝深度小于35 mm,扰动应变为12~18με的压应变;扰动应变可在测试应变中扣除,以消除其对测试精度的影响。切缝深度越大,测试精度越高,但对混凝土的损伤也越大,若采用直径125 mm切割片,建议切缝深度控制在30~35 mm。单缝法能够有效测试混凝土工作应力且具有较高的精度,对于测试试样,测量误差少于8.5%。The concrete working stress is the stress increment relative to the stress-free state.To accurately measure the concrete working stress,a micro-damage method for measuring concrete working stress,i.e.,the single-groove method,was proposed based on the concept of‘strain partial release’.The single-groove method released stress by cutting a shallow and narrow curved groove and calculates stress by measured strains.The method’s effectiveness was verified using numerical simulations,and the influences of the parameters,such as the elastic modulus of concrete,on the strain release rate were analyzed.The strain release rate was the ratio of the strain released by cutting to the initial strain in concrete.The effects of the parameters,including the stress magnitude and groove depth,on the testing accuracy were investigated by experiments.The results show that the strain release rate is uniquely determined by the shape and size of the groove and is independent of the elastic modulus,stress magnitude,and groove width.Therefore,given the shape and size of the groove,the corresponding strain release rate can be determined by numerical simulation or experiment.The release strain is distributed in an‘M’shape along both sides of the groove,and increases first and then declines with the distance away from the groove.The strain gauge shall be arranged where the strain is significant and monotonic.Using the single-groove method to measure the concrete working stress,it is recommended to utilize a 50 mm strain gauge and arrange it 25 mm away from the edge of the groove.The deeper the groove,the greater the disturbance strain generated by cutting.The disturbance strain is compressive and ranges from 12 to 18μεwhen the groove depth is less than 35 mm.The disturbance strain can be deducted from the test strain to eliminate its impact on testing accuracy.The deeper the groove,the higher the testing accuracy,but the greater the damage to the concrete.Using a cutting disc of a diameter of 125 mm,the groove depth ranging from

关 键 词：混凝土 工作应力 释放应变 应变释放率 单缝法 

分 类 号：TU317[建筑科学—结构工程]