فصلنامه جاده
سال بیست و دوم شماره 3 (پیاپی 80، پاییز 1393)

Earthquake damage to a bridge can have server consequences. Clearly¡ the collapse of a bridge places people on or below the bridge at risk¡ and it must be replaced after the earthquake unless alternative transportation paths are identified. The consequences of less server damage are less obvious and dramatic¡ but they are nonetheless important. A bridge closure¡ even if it is temporary¡ can have tremendous consequences¡ because bridge often provides vital links in a transportation system. In the immediate aftermath of an earthquake¡ closure of a bridge can impair emergency response operations. Later¡ the economic impact of a bridge closure increases with the length of time the bridge is closed¡ the economic importance of the traffic using the route¡ the traffic delay caused by following alternative routes¡ and the replacement cost for the bridge. The purpose of this paper is to identify and classify types of damage to bridges that earthquake commonly induce and¡ where possible¡ to identify the causes of the damage. This task is not straightforward. Damage usually results from a complex and interacting set of contributing variables. The details of damage are often obscured by the damage itself¡ so that some speculation is required in reconstructing the event. In many cases¡ the cause of damage can be understood only after detailed analysis¡ and even then¡ the actual causes and effects may be elusive.

The high volume of construction using asphalt in Iran and the weakness of the bitumen produced in the country¡ during the time of utilization has caused several kinds of failure. Gilsonite in class¡ reform of the bitumen to the hydrocarbons belong¡ a substance that can be in the modification of bitumen and its subsequent correction of mixtures of asphalt used especially with the increase of pure bitumen price¡ the use of organic bitumen in asphalt production has a direct economical benefit for the country. On the other hand with the increase of bitumen and asphalt property produced¡ the quality and the life of road surfaces will increase. The effects of organic bitumen on common functional properties of bitumen such as softening point¡ penetration ¡ viscosity ¡ gum plasticity ¡ weight loss ¡ weight gain and boiling point. In this research¡ by adding Gilsonite to the bitumen samples with the percentage of 0¡ 2¡ 4¡ 6¡ 8 and 10 after performing several experiments the most suitable criteria of optimal additives were determined using Analytical Hierarchy Process AHP methodology.

The results from the NCHRP 9-19 project recommended three candidate Simple Performance Test (SPT) tests: flow time (FT), flow number (FN), and dynamic modulus |E*| tests. In addition, the dynamic modulus test was selected for the HMA materials characterization input utilized in the 2002 Mechanistic and Empirical (M-E) Guide for Design of New and Rehabilitated Pavement Structures, developed under NCHRP Project 1-37A. The rutting model selected in the M-E design guide for the asphalt concrete layer is based on an empirical relationship between the elastic strain and the plastic strain, where the computation of the elastic strains is derived from the |E*| values. However, as demonstrated from the results presented in this paper, if the |E*| value itself can not differentiate between poor and good performing HMA mixtures in terms of permanent deformation resistance, it is cautioned that the rutting prediction provided in the M-E design guide may not provide the true mixture performance. Currently, there is interest in incorporating flow number as the additional test method. The objective of this research study is to evaluate and compare several methods to be used in calculating the onset of tertiary flow (referred to as flow number (FN) parameter) for asphalt mixtures.

Climate diversity, bitumen price increase, and such failures as premature aging and limited heat resistance of domestic bitumen products make necessary the use of methods that increase pavement desireability and durability. Rubber asphalt not only makes bitumen production economical, but it also decreases the environmental pollution, improves resistance against fatigue and heat cracks, reduces rutting and, most important of all, reduces the maintenance costs and increases the pavement life expectancy. In this research, an optimum mixture of bitumen, rubber powder, and rubber oil was obtained using high shear velocity mixers. Rubber powder increases softening point and permeability index, but decreases penetration rate and Fraass breaking point. Rubber oil increases low temperature tolerability and gives good stability to rubber asphalt.

Road traffic safety refers to methods and measures for reducing the risk of a person using the road network being killed or seriously injured. The users of a road include pedestrians, cyclists, motorists, their passengers, and passengers of
on-road public transport, mainly buses and trams. Best-practice road safety strategies focus upon the prevention of serious injury and death crashes in spite of human fallibility (which is contrasted with the old road safety paradigm of simply reducing crashes assuming road user compliance with traffic regulations).In this paper, we performed a systematic review on road traffic safety methods. The first attention is paid to road safety issues and its improvement measures along with the safety promotion strategies of vulnerable road users and finally the road traffic safety theories created by relevant organizations is evaluated.

Result of an underground tunnel designation is determining the static and seismic forces generated in the tunnel lining. For calculating of these forces in static and quasi- static mode¡ several relationships have been presented that briefly in this article is cited. Then for two tunnels with circular and square sections¡ numerical- seismic analysis were done and the results are compared with each other. According to the results¡ the axial force created in the circular tunnel lining in static and seismic conditions¡ is greater than those in square tunnels¡ but bending moment and shear force in square tunnel are larger than those for the circular tunnel. The resulting forces of seismic analysis of circular tunnel averagely are 12 times of static analysis and for the square tunnel are 6 times of the static analysis. Ground surface settlement profile in static mode is symmetric¡ and settlements above the square tunnel are greater than those for circular tunnel. Ground surface settlement profile is asymmetric in seismic condition¡ but the settlement values are almost identical for both sections of the tunnel.
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Given that water infiltration into tunnel resulted in damage of tunnel construction equipment¡ personnel and tunnel construction process¡ tunnel designer must determine the amount of water infiltration volume into tunnel before the construction of tunnel began. Knowing the water infiltration volume could be effective in choosing appropriate tunnel boring technic and designing tunnel support and drainage method. According to various studies¡ water has the main source of tunnel detoriation in serviceability stage while the water proofing method used in these tunnels. Experience shows that construction tunnel lining with complete waterproofing are expensive and sometimes it is not practical. So¡ depending upon the use of subsurface facility¡ the permissible leakage defined and this permissible amount of water collected by the drainage systems and conduct to out of tunnel. There are many factors that affect the permissible water leakage. Also in the most of tunnel standards and guidelines¡ the permissible water leakage suggested. If we use standards with high safety factors¡ then we must use expensive material¡ needs more time and high experienced supervisor. In this paper¡ the permissible water leakage based on different standards in road and railway tunnel presented. In our country¡ there is no standard that proposed permissible water leakage. So the permissible water leakage determined based on personal experience and this caused conflict between contractor¡ supervisor and employer.