针对依托工程腊八斤特大桥,选取主桥10#墩的0#块节段建立局部有限元模型,通过数值分析,对0#块横隔板的受力状态及横隔板横向预应力钢束布置形式进行对比分析研究,提出横向预应力钢束的合理布置形式。

基于风险评估理论,针对姚河坝小净距隧道雅安端小净距、大偏压、差地质情况,研究了暗挖进洞的位置,通过分析了各方案的风险等级,确定了错开进洞方案,并对比分析了可选择的子方案,探讨关键点及注意事项,对类似工程设计具有参考价值。

Baling river grand bridge is located in special mountainous area with very complicated wind field which is the representative case in west China.The particular terrain model,which can simulate the practical status of wind field in bridge site,was tested in wind tunnel to confirm the design norm wind speed and the related wind characteristic parameters to give reference to future similar bridge designation,and the test method was researched to identify the correctness and reliability at the same time.The test result shows that(1) the wind speed increases obviously at the height of mid-span girder because of the effect of narrow under cross wind;(2) the distribution of wind profile is nonuniform,the average attack angle range is ±4.7° degree,obviously lager than the required ±3° in criterion;(3) the power spectra of lateral and vertical fluctuant wind speeds at the high frequency part are close to those listed in criterion,while there exists clear difference at low frequency part.The Von Karman fluctuant wind speed power spectrum was used in this research.

甘肃省S216线红石山至桥湾公路位于干旱寒冷地带,路面病害严重,影响道路通行能力,我们引用油砾石技术提高路面质量。本文结合油砾石试验的病因分析,指出在干旱寒冷地区铺筑油砾石路面注意的问题。

The aim of the study was to develop a procedure for determining freeway work zone speed limits usable during the construction phase of a roadway maintenance project. The most desirable work zone speed limit should minimize the accident rate as well as ensure the capacity. Research by others showed that accident rates increase with deviation from the mean speed, so the speed limit should minimize the speed standard deviation. To save time, the method of microscopic simulation was utilized. The parameter set of the microscopic simulation model for work zones in the freeway was validated by using the data collected in the work zones by means of orthogonal experimental design. The simulations were run for various traffic volumes and compositions and the model between the speed limit and the speed standard deviation was built as well. The result is that speed limit lowered by 30 km/h downwards in work zones compared to the upper section can decrease the speed standard deviation and the potential accidental rate the most and the capacity can be maintained at the same time.

Taken a grand long-span suspension bridge with truss girder for example,the influences of various aerodynamic controlling measures such as central-slotting in bridge deck plate,apron board and pneumatic winglets on the critical flutter wind speed of the girder was discussed through sectional model wind tunnel test.The test results indicate that (1) the flutter stability of bridges with truss girder can be improved by use of central-slotting in bridge deck plate,apron boards and pneumatic winglets,however,any of these measures cannot increase the critical flutter wind speed of the girder at all of angles of attack;(2) the combination of central-slotting in bridge deck plate and pneumatic winglets which is located on stiffening chord is the optimalest one.This research can provide a reference for the wind resistant design of long-span bridge with truss girder.

The paper is to present the results of our experimental research results on the aerodynamic characteristic parameters in wind-breaking net wind resistance. Though so far few relevant research data can be found in this connection, we do believe it is badly in need of pushing the research with the wind tunnel testing and experiments so as to produce due static wind load aerodynamic characteristic parameters. So far we have found that two types of wind leak ratio with the papilionaceous and flat windbreak net were respectively 29.9%, 35.4%. The results of our experiments show that the wind shape factors are negative with large absolute number at the wind-free side whereas positive at the windward side. Furthermore, the factor proves negative if the wind leak ratio is small, whereas it would be positive if the wind leak ratio is large. Therefore, the wind load of windbreak net is mainly represented as a kind of suction force. On the other hand, when the wind pressure loss coefficient increases, the wind shape factor and wind drag force coefficient would in turn rise in a remarkable consistency. Thus, the better effect of windbreak and the weaker repression performance, the worse or weaker the wind resistance capability would become. Therefore, the best project should be determined by selecting the best harmony of the wind load and windbreaking effect in the structured wind resistance designation. In a word, the results of this paper can be taken as a reference to the actual windbreak net wind resistance designation so as to obtain the optimal aerodynamic characteristic parameters.

Based on psychological theories, the paper analyzed the relationship between the acuity and the brightness ratio of the letter and background in guide signs. Because the luminance values for the five grades of the retro-reflective sheeting were constant and the gap was wide in the GB5768-1999 Traffic Signs and Markings on the roads, the luminance values of the background were adjusted dynamically by adding declining sheeting onto it. By field experiments, the impact of the grade of retro-reflective sheeting on the visibility was studied, and the relationship between the luminance values and visibility distance was established. The results show that there exists a certain brightness ratio which can optimize visibility, and we get the best configuration for the retroreflective sheeting grade of letter and background when the luminance value of the letter is 600 cd·lx-1·m-2, that of the background is 92.5 cd·lx-1·m-2 with a visibility distance of 141.9m,which indicate that the current grade of the signs is high, and should be lowered.

Two-lane, one-way freeways compose a large percent of the freeway system nationwide. Preserving, expending, and enhancing these freeways result in many work zones which have caused a safety concern for the traveling public. Aimed at reducing crashes attributed to the existence of these work zones, an evaluation of speed reduction measures was carried out in work zones of the freeway. The speeds before and after three speed reduction strategies were measured. The mean and 85 percentile speed, and the standard deviation of the speed were analyzed statistically. It can be concluded that the effect of the individual warning sign was very limited, which can not achieve the desired results. However, the three dimensional speed markings made sense, which can reduce the mean speed by 10.4 km/h; but in the meantime the standard deviation of the speed increased because many drivers misunderstood it, got confused or braked a vehicle suddenly. Besides, the effect of the speed limit sign with camera graph was very obvious, which made the mean speed slow down by 17.3 km/h, and standard deviation of the speed fell as well. So the speed limit sign with camera graph could be used in the work zones of the freeway to control the speed while the warning sign, and the three dimensional speed markings were not recommended. Keywords-Work zone, Traffic safety, warning sign, Three dimensional speed markings, Speed limit sign with camera graph

Through the wind tunnel test for the sectional mode of Baling River Bridge,the static three-component coefficients and the fluttering characteristics of the main girder of the Bridge were obtained,the eight fluttering derivates of the main girder were identified and the results of the test were analyzed in detail.The analysis and evaluation of the results can be used to guide the design and construction of the Bridge and can also serve as reference to the bridges of similar kind.

四川攀西高速公路的白沙沟1号桥为国内第一座悬臂浇注的拱桥,跨径为150 m。在拱桥悬浇挂篮的研制过程,有比较多的创新点,可为同类桥梁和悬臂浇注桥梁的挂篮设计提供新的思路。

Based on the vegetation planting for expressway of Xining to Machangyuan,this article mainly studied the regularity of the plant's succession,and the adopted management measures.According to the weather,physiognomy and soil in Xining area,and the problems in the vegetation conservation,lots of observations and experiments were carried out.After analyzing the data by using the(ecological) principles,this article discussed the succession trend of the flora in this area,and the existing problems of the adopted(management) measures.On the base of the succession regularity of the flora in this area and the special demand to the plants of the local expressway,this article put forward some pertinent suggestions.

On the basis of the origin and the definition of the Safety Assessment,the definition and the medium of the Highway Safety Assessment(HSA) are discussed as well as the methods and the stages in which these methods can be used.The qualitative methods of the HSA are Standard/Specification accordance check and Highway Safety Audit.The quantitative methods are based on the mathematics and statistics to find the quantitative relationship between the highway safety and its influence factors.The quantitative methods can choose the following media:accident,speed,conflict and drive workload etc.And the methods are accidents-based identification,accident prediction,speed consistence,traffic conflict technology(TCT),drive workload consistence.The latest research results of the accidents-based identification,accident prediction and speed consistence are introduced.The following research work on the TCT and drive workload consistence is also put forward.

The expressway is featured by the high traffic capacity, comfort, low transport cost and outstanding economic efficiency, which have become an important part in the overall transport system in China. However, inspire of all its advantages of high efficiency, rapidness and convenience, it also imposes negative effects on traffic accidents. This article addresses and analyses in details on the aspects of the current safety status, features of the traffic accidents and the reasons in the expressway transport.