摘要
为克服泡沫半衰期测定过程中无法施加压力及读数误差等问题,自主研发了泡沫性能测试系统,该系统由泡沫生成模块、压力条件下泡沫衰变细观图像采集模块及泡沫半衰期测定模块等组成,可同时测定压力条件下泡沫衰变过程中的平均半径及溶液析出量半衰期。使用该系统测定了不同试验压力(0、50、100、150、200 kPa)及不同泡沫剂体积分数(2.0%、2.5%、3.0%、3.5%、4.0%)下泡沫的平均半径演变规律与半衰期,并在两者之间建立了统一的联系,基于此提出了土压平衡盾构渣土改良泡沫半衰期细观测定方法。首先,使用观测窗与显微镜采集泡沫衰变过程中不同时刻的衰变图像,然后通过图像处理软件Image J获取衰变图像中泡沫的等效半径,进而得到其平均半径比演变规律,然后通过所提出的公式确定特定压力与不同泡沫剂体积分数下半衰期时刻泡沫的平均半径比,最后根据半衰期时刻的平均半径比计算泡沫的半衰期。该方法采用“显微镜采集图像+软件统计半径”的方式获取泡沫衰变过程中其等效半径的演变规律,从而确定泡沫半衰期,避免人为读数带来的误差,且泡沫衰变过程中环境压力可调节,能够再现渣土改良过程中泡沫所处的压力环境。最后使用试验数据对该方法的准确性进行了验证,结果表明:通过该方法确定的泡沫半衰期最大相对误差(相比于传统衰落筒半衰期)低于5%,最大绝对误差低于38 s,该方法具有较高的准确度。
There are many drawbacks to using the measurement method for foam half-life.For example,only the foam half-life at atmospheric pressure can be measured,and the measurement error of the foam half-life is determined through foam solution precipitation.A foam performance-testing apparatus was developed to solve these problems.The apparatus consisted of a foam generation module,mesoscopic image-capture module of foam decay under pressure(gauge pressure),and measurement module of foam half-life.The apparatus can simultaneously measure the foam half-life of solution precipitation and mean bubble radius during the foam decay process.The evolution of the mean bubble radius and half-life of the foam were measured using the apparatus under different pressures(0,50,100,150,200 kPa)and foam agent concentrations(2.0%,2.5%,3.0%,3.5%,and 4.0%),and their relationship was established.Subsequently,a mesoscopic measurement method of the foam half-life for the soil conditioning of the earth pressure balance shield was developed.First,images of the foam decay at different times were captured using an observation window and microscope.Second,the equivalent radii of bubbles in the foam decay images were determined using Image J,and the variation in the mean bubble radius ratio was determined.Third,the mean radius ratio at the half-life time under specific pressure and foam agent concentration was calculated using the proposed formula proposed in this study.Fourth,the foam half-life was calculated using the mean radius ratio at the time of half-life obtained in the previous step.In this method,the variation in the equivalent bubble radius during the foam decay process is obtained using microscope-captured images and counting radius software,and the foam half-life is determined.This method prevents errors caused by artificial factors.However,the environmental pressure of the foam decay process can be adjusted using this measurement method to precisely restore the pressure environment of the foam under soil conditions.Finally,the accuracy of the method was verified using experimental data.The results show that the maximum relative error of the foam half-life determined using the proposed method is lower than 5%,and the maximum absolute error is less than 38 s.The accuracy of this method is high.
作者
赵世森
李树忱
王鹏程
袁超
万泽恩
王曼灵
ZHAO Shi-sen;LI Shu-chen;WANG Peng-cheng;YUAN Chao;WAN Ze-en;WANG Man-ling(School of Qilu Transportation,Shandong University,Jinan 250002,Shandong,China;School of Civil Engineering,Shandong University,Jinan 250002,Shandong,China)
出处
《中国公路学报》
EI
CAS
CSCD
北大核心
2022年第4期195-202,共8页
China Journal of Highway and Transport
基金
国家自然科学基金项目(51879150)
国家自然科学基金重点项目(41831278).
关键词
隧道工程
细观测定方法
泡沫半衰期
渣土改良
平均半径
土压平衡盾构
tunnel engineering
mesoscopic measurement method
foam half-life
soil condition
mean radius
earth pressure balance shield
