基于无损检测技术的白加黑路面病害探测与评价

为更加准确探测白加黑路面的结构层内部隐性病害，依托茂湛高速改扩建项目白加黑路面，采用三维探地雷达技术开展既有路面的病害检测，并结合落锤式弯沉仪进行白加黑路面的结构承载能力测试。结果表明，采用三维探地雷达设备可以清晰识别白加黑路面结构断板、裂缝、脱空、传力杆布设等内部状况信息，能反映出原有路面结构内部各层位病害的总体情况。在多年车辆荷载作用下，白加黑路面的反射裂缝病害比例较高，建议采取注浆、灌缝等养护措施，加强对旧水泥板与沥青层开展稳固与密水处理；水泥路面加铺沥青层后，路顶弯沉值整体变小，有无沥青层的弯沉差值主要与沥青加铺层厚度、模量、老化程度有关。为了更好模拟实际轮载对路面的荷载作用，推荐采用10 t荷载进行板间弯沉差测试，并以弯沉差为0.05 mm以上为处治阈值，进行针对性地补强处理。     

公路刚性路面裂缝问题探讨

水泥混凝土路面与其他路面相比,具有强度高、稳定性好、耐久性好、养护费用少等许多优点,在我国一些城市道路、高等级公路、干线公路广泛采用,水泥砼路面的比重越来越大.但是,水泥混凝土路面一旦出现病害、修复起来非常不.混凝土路面的病害种类很多,其中裂缝是危害最大的一种,有些其他病害首先是从裂缝开始的.因此,对混凝土路面裂缝进行调查,分析其成因,从而制定相应的对策意义重大.通过对病害调查和修复过程的观察分析,对一些主要裂缝的形成原因进行剖析,提出一些相应对策,供大家参考.     

水泥混凝土路面的损坏分析与治理对策探讨

水泥混凝土路面的病害对于行车速度、安全及舒适性具有重要影响。本文分析了水泥混凝土路面的四大类损害:断裂类病害、竖向位移类病害、接缝类病害、表层类病害,对各类病害的类型及轻重程度分级进行了详细讨论,而后探讨了水泥混凝土路面病害的处治对策,并提出了相应的预防建议。     

常州市239省道路面养护改造处治方案研究

文章以常州市239省道路面大修工程中的沥青路面的养护改造为例,采用人工调查旧沥青路面的病害,通过路面状况指数(PCI)、用路面结构强度指数(PSSI)、路面行驶质量指数(RQI)、路面车辙深度指数(RDI)对路面进行评价,并结合病害严重区域的钻芯取样分析病害产生的原因。根据调查与分析结果,针对不同情况,提出了不同的养护改造方案,为旧沥青路面的处治提供参考。     

水泥混凝土路面裂缝原因及防治措施

简要地叙述了水泥混凝土路面在施工中容易出现的病害,分析了混凝土路面的不规则微裂缝、路面通缝、路面跑砂、起皮等质量通病的原因,并论述了施工中采取的应对措施,确保路面工程质量.     

浅谈水泥混凝土路面裂缝成因及预防措施

随着水泥混凝土路面修筑技术的日臻完善,水泥混凝土路面发展的速度较快,在技术、经济上也将显示出明显的优势。然而水泥路面的迅速增长,水泥混凝土路面的许多病害也逐渐体现出来。文章通过多年来的工作经验,总结了水泥路面裂缝的成因,并提出了相应的措施,与同行共同探讨。     

探地雷达在公路改扩建工程检测中的应用

公路改扩建工程在广东省正处于快速发展时期,如何准确得到路面病害情况,是旧路处治方案制定面临的主要问题.依托开阳高速改扩建工程,采用三维探地雷达对旧路进行病害检测,得到道路表面及内部的病害分布情况,并分别与人工徒步调查路况及开挖后内部实际情况进行比对.结果表明:当三维探地雷达检测采样间距设置为2.0 cm、驻波时间设置为0.6 ms、时窗设置为85 ns时,可达到较好的检测精准度;三维探地雷达可实现对路面结构内部不同深度位置的裂缝病害进行探测,精确识别3 mm宽裂缝,并了解裂缝的发展方向及性质.     

高速公路沥青混凝土路面破损状况评价

随着我国高速公路建设的加快和养护管理的深入,如何客观科学地对高速公路沥青混凝土路面的破损状况进行评价逐渐成为关注的热点和难题。本文在分析现行的路面破损评价指标不足的基础上,提出了应用路面车辙指数、路面等效裂缝率指数和路面等效修补率指数这三个指标对高速公路沥青混凝土路面破损状况进行分析,克服了原有评价指标的缺陷,有利于道路养护决策方案的实施。     

水泥混凝土路面病害原因浅析

水泥混凝土路面由于使用寿命长、造价相对较低、能充分利用地材、承载能力强、稳定性好等优点,从上世纪80年代以来,作为路面结构的主要形式之一,在我国大部分地区得到了广泛使用,许多省际干线公路建成了造价相对便宜的水泥混凝土路面,但大部分混凝土路面不同程度的出现了裂缝、坑槽、唧泥、变形等病害,难以承担高等级公路之重任,严重影响路面使用寿命、行车安全及行车舒适性,本文就水泥混凝土路面常见病害成因进行分析,提出预防对策。     

沥青混凝土路面常见病害的预防与处理

目前,我国沥青混凝土路面最常见的早期病害现象有:裂缝、水破坏、松散、泛油、推移等。本文分析常见病害的成因并结合实际提出相应的预防措施。一、沥青混凝土路面早期病害预防措施(一)裂缝。对于温度变化引起的温度裂缝,在其他条件相同的情况下,采用较稀的沥青有利于减少温度裂缝。对于沥青面层因基层施工质量不高而引起的反射裂缝,在基层施工中,及时地养护、良好的接头处理可以有效防治沥青面层反射裂缝。(二)水破坏。(1)选择合适的混凝土类型,沥青面层各层应尽量使用空隙率≯5%的密实型沥青混凝土。(2)使用     

基于无损检测技术的机场道面承载能力评价应用

机场跑道路面的隐性结构病害严重威胁飞机的运行安全,为了准确、及时对道面结构承载能力进行检测和内部结构病害的精准识别,依托广东白云机场开展跑道道面无损检测技术研究。采用落锤弯沉仪法获取的弯沉盆反演道面结构层弹性模量,联合水泥板间弯沉比传递系数,可以全面评价机场道面承载能力,模量偏低的道面水泥板,其板间弯沉比传递系数偏小,二者间存在良好的映射关系。采用三维探地雷达技术开展道面结构层内部病害检测,发现弯沉比传递系数偏低位置出现传力杆断裂、变形,混凝土板内部破碎,接缝处积水等问题,建议对不同病害开展分质处治措施。两种无损检测技术的结合可以高效检测与评价跑道道面路用性能,也为路面病害探测与处治提供准确可靠的技术依据。     

探地雷达法检测路面板脱空病害的研究

由于城市路面板脱空危害极大，传统笨重、复杂的检测方法和钻探有损检测方法已不再适用。通过分析探地雷达（GPR）法检测路面脱空的基本原理，借助 GprMax及 MATLAB软件编程实现对路面板脱空模型的正演模拟试验，对比不同类型路面板下的脱空病害响应特征，初步获得路面板脱空病害正演模拟图像特征规律。结果表明，不同类型路面板下的脱空病害特征图谱一致性较好，路面板下的脱空病害体波组形状表现为似平板状，顶部反射信号能量明显增强，多次反射波发育。用正演模拟结果指导实际工程应用，取得了较好的效果。     

Sex,Race, and Job Satisfaction Among Highly Educated Workers

There has been a considerable amount of work focusing on job satisfaction and sex, generally finding that women are more satisfied than men despite having objectively worse job conditions. But there is little evidence on whether job satisfaction differs by race or ethnicity. We use data from the 2010 National Survey of College Graduates to examine the relation between job satisfaction and race and ethnicity among Asian, black, Hispanic/Latino, and white workers. Overall job satisfaction does not differ by sex among college graduates. Relative to white workers of the same sex, Asian and black workers are far less satisfied. The lower satisfaction of Asian and black workers relative to white workers is not explained by immigrant status, job match, or other individual or job characteristics.     

Assessing black progress: employment,occupation, earnings,income, poverty

Farley discusses changes in employment, occupation, earnings, income, and poverty among US blacks. Among black men, there has been a persistent rise in unemployment since 1960. By the early 1980s, 1 black man out of 8 had dropped out of the labor force, compared to 1 in 20 white men. Some contend that many black men lack the skills to be employed or have personal habits and criminal records which make them unacceptable to employers. Others believe that the expansion of federal welfare programs offers attractive alternatives to men who have limited earnings potential. Still others stress that blacks are concentrated within cities, while the growth of employment is occurring in suburbs. Among those blacks over age 54, labor force participation has declined because of improved Social Security benefits, better private pensions, and the greater availability of Supplemental Security Income. The employment of young blacks compared to whites has deteriorated since 1960. For both races, there has been a steady rise in the employment of women. The recent increases, however, have been great for whites. By the early 1980s, white women caught up with black women in terms of employment. Unlike the indicators of employment itself, there is unambiguous evidence that the occupational distribution of employed blacks has been upgraded and is gradually becoming similar to that of whites. Findings from many studies show that blacks once earned much less than similar whites, but this racial difference has declined among men and has nearly disappeared among women. The proportion of blacks impoverished fell sharply in the 1960s, reaching a minimum of 30% in the early 1970s. Since the early 1970s, blacks have made few gains. The proportion impoverished actually increased and the ratio of black-to-white family income declined. The fact that the earnings of black males are no longer rising faster than those of whites and that there is no longer a migration from southern farms to cities plays a role, but changes in family structure are also important. At all dates, poverty rates have been high and income levels low in families headed by women. In 1984, for example, 52% of the black families with a woman as head of household were below the poverty line, compared to 15% of the black married-couple families. While similar trends are occurring in white families, there has been a sharper increase in the proportion of blacks living in these female-maintained families which have high poverty rates.     

The economic interests of black and white women: Are they similar?

Are the economic interests of black and white women similar? This article explores this question by reviewing data on the “feminization of poverty,” data on changes in the economic status of blacks, and differences in the occupational status of black and white women. The article reviews several policy questions, discusses ways in which the interests of black and white women differ in the policy arena, and concludes that although there are some similarities in the interests of black and white women, the racial interests of black women suggest that the interests of black and white women may frequently differ.     

Effects of community,family, and education on earnings of black and white men

Summary The primary purpose of this paper was to determine the effect of background on the education and earnings of black and white men.It was largely motivated by a desire to quantify the extent to which past discrimination against Blacks, resulting in lower achievement, inhibits the progress of individuals today in a somewhat more benign environment.It has demonstrated that both community and family background factors are important in determining the levels of education and earnings of black and white men.The community effects for Blacks operate largely through their moving into more integrated neighborhoods, so that many positive community externalities are apparently not available to families in predominantly black middle-class neighborhoods.While the effects of father’s education, city origin, and community income are comparable between Blacks and whites, white men’s education is more affected by number of siblings, family income, and age of 1968 head of household than is black men’s education.The relative sizes of the coefficients of these latter variables are consistent with steeper age-earnings profiles for older white men than older black men and higher prices paid for investing in children by black parents.     

Price discrimination in physician services markets based on race: New test of an old implicit hypothesis

Prior econometric studies of physician fee determination report that fees are positively related to the proportion of the market area that is black and negatively related to the proportion of the market area that is white, but the studies provide only sketchy explanations for these results. This article presents a price discrimination model which explains the empirical results and provides the specific prediction that low income self-pay consumers in the black community constitute the group that pays higher prices for physician services. The study then replicates prior econometric results on a more recent national database, but finds that the results are sensitive to specification. When geographic differences are controlled for in the empirical model, the results fade and a statistical test indicates that the expanded specification is superior to the specification which replicated the price discrimination result. The conclusion is that there is no compelling evidence of price discrimination in physician services markets based on race.     

Comparative labor supply of black and white women

Conclusions The presence of young children decreases women’s labor supply as shown by the LFPRs for women with young children (which are always considerably lower than those for women without young children). Also, the number of young children is almost always negatively related to annual hours of labor supplied (significantly so in half the regressions). Black and white women are found to have an inelastic labor supply, but with increasing elasticity from 1969 to 1974. There is a statistically significant difference in the estimated regression coefficients of the labor supply model for black and white married women in 1969 and 1974 in both the arithmetic and logarithmic forms. The husband’s earnings are significantly negatively related to white married women’s annual hours of work in 1974, while the relationship is not significant for black married women. Crosselasticity terms show that white married women decrease their annual hours of work in response to an increase in husband’s earnings to a greater extent than black married women in 1971 and 1974. These results are consistent with the hypothesis that black women do not rely on their husband’s earnings to as great an extent as white women.     

An Analysis of Perceptions of Job Insecurity among White and Black Workers in the United States: 1977–2012

While objective measures indicate that the risk of job loss is higher for black workers than for white workers, there is little research on how what workers’ expectations of job loss differ by race. This study looks at how secure black and white workers are feeling about their jobs and how their perceptions of job insecurity have been affected by time trends and regional unemployment rates. I find that perceptions of job security of black male workers, older black workers, and black high school graduates have deteriorated relative to their white counterparts during the period 1977–2012. Among those who attended college, white workers’ perceived job insecurity has increased. Black blue-collar workers’ and construction workers’ perceptions of job insecurity also have increased relative to their white counterparts. Moreover, perceptions of job insecurity among several black groups, such as high school dropouts and old workers, are more sensitive to regional unemployment rates than their white counterparts.