Modiﬁcation and application of axle load conversion formula to determine traﬃc volume in pavement design
|نوع نگارش مقاله||
scopus – master journals – JCR
۴٫۲۷۶ در سال ۲۰۲۰
۲۶ در سال ۲۰۲۱
۰٫۹۰۱ در سال ۲۰۲۰
|شاخص Quartile (چارک)||
Q1 در سال ۲۰۲۰
خرید محصول توسط کلیه کارت های شتاب امکان پذیر است و بلافاصله پس از خرید، لینک دانلود محصول در اختیار شما قرار خواهد گرفت و هر گونه فروش در سایت های دیگر قابل پیگیری خواهد بود.
فهرست مطالب مقاله:
The determination of traﬃc volume in asphalt pavement design has not considered the eﬀects of seasonal variability on vehicle axle loads in China. By analyzing the eﬀects of seasonal variation on the axle loads, formulas for the conversion of modiﬁed axle load to traﬃc volume have been derived and presented, in accordance with speciﬁcations in China. This study includes the following: derivation of formulas for converting modiﬁed axle loads to traﬃc volume, classiﬁcation of 3 diﬀerent seasons, determination of seasonal distribu- tion and inﬂuencing coeﬃcients, and application of modiﬁed axle load conversion formulas, among others. By comparison of results between modiﬁed and unmodiﬁed formulas applied in a sample asphalt pavement design in Harbin, China, the study demonstrates that the modiﬁed axle load conversion formulas are scientiﬁc and rational. The results of asphalt pavement design obtained using the mod- iﬁed axle load conversion formulas increase the thickness and whole strength of the asphalt pavement structure; in addition, it can more eﬃciently satisfy the requirements of an actual vehicle running on the pavement.
|بخشی از متن مقاله:|
Most asphalt pavements are designed based on the stan- dards of pavement surface deﬂection and tensile stress of the pavement layer. Tensile and compressive strains at dif- ferent depths in the pavement system are critical responses to fatigue and rutting criteria. Design standards are deter- mined based on the volume of traﬃc axle loads. However, in the speciﬁcation of the asphalt pavement design (JTD D50-2006) in China, the eﬀects of seasonal variability on the axle load are not considered in the conversion of axle load to traﬃc volume. The axle load spectrum (ALS) was aggregated into a number of equivalent single axle loads. This characteristic aﬀected the accuracy and computational performance of the pavement analysis. The analysis of equivalent axle load factors on the basis of fatigue criteria used in various mechanistic-empirical methods of pavement design was presented [۱,۴,۵]. A model for calculation of equivalent axle load factors (EALFs) was developed by considering the type of axle, the type of wheel and the constitution of the pavement . Experimental pavement deterioration data gained from accelerated load testing (ALT) were used to derive relative performance factors for rutting and rough- ness deterioration for increases in axle loads . The ade- quacy of using conventional traﬃc data and national default values in the absence of weigh-in-motion (WIM) data for pavement design was examined, and a compara- tive study was conducted on Arizona USA . Equivalent conversion method of asphalt pavement axle-load skid-
resistance performance was determined . A three- dimensional ﬁnite element model was utilized to simulate the AASHO road test pavement sections and to develop load equivalency factor (LEF) formulae for various pave- ment sections under various axle loadings . The fatigue damage caused by multiple-axle conﬁgurations is a key issue for pavement design, and a method for the computa- tion of the fatigue life of bituminous mixtures under multiple-axle conﬁgurations was presented . All afore- mentioned research has been focused on axle load spec- trum and its model, but the modiﬁcation of axle load aﬀected by seasonal factors has not been involved to any signiﬁcant extent.
Fig. 1 shows how seasonal variability aﬀects pavement performance under the same traﬃc loads.
In accordance with the speciﬁcations in China, aspects which contribute toward seasonal variability in traﬃc vol- ume mainly include the following:
(۱) Requirements with respect to subgrade consistency in asphalt pavement design.
(2) Strength indexes of asphalt and asphalt mixtures, which are determined based on only one temperature.
(3) Eﬀects of seasonal variability on pavement deﬂection in the refurbishment of an old asphalt pavement.
Analysis of the 3 aforementioned aspects indicates that these aspects have not entirely considered the eﬀects of sea- sonal variability on traﬃc volume. In fact, the design parameters (deﬂection, resilient modulus, etc.) of subgrade and pavement materials can be inﬂuenced by temperature and humidity of diﬀerent seasons. The resilient modulus of the subgrade soils can be signiﬁcantly inﬂuenced by in situ moisture content, and the resilient modulus of the pavement materials can be inﬂuenced by temperature. Thus, the pavement structure can be damaged given the same traﬃc axle loads because of seasonal variability, or the volume of traﬃc axle loads can increase for the same pavement structure.
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