Development of a driving cycle for Colombo,Sri Lanka: an economical approach for developing countries

Financial constraints and lack of availability of traffic‐related information significantly hinder the development of driving cycles in developing countries. This paper proposes an economical, practical, accurate methodology for the development of driving cycles, including the development of a driving cycle for Colombo, Sri Lanka. The proposed methodology captures regional traffic and road conditions and selects a model that represents the collected data sample with minimum available traffic‐related information. Existing methods were modified for route selection by dividing routes into links using nodes or physical junctions to minimize the number of trips required for data collection. Speed–time data for respective links were used to reconstruct speed–time profiles of identified origin–destination pairs. The on‐board method was used for data collection, and the Markov chain theory was used to develop a transition probability matrix of state changes. An additional matrix was introduced to the existing method to improve model representativeness to the collected data sample. Copyright © 2016 John Wiley & Sons, Ltd.     

试样尺寸及制样粒径大小对粗粒土三轴试验抗剪强度的影响

三轴试验是确定土的抗剪强度的主要方法,试样尺寸是影响三轴试验结果的重要因素之一.粗粒土的三轴试验需要采用大尺寸的试样进行,相应需要采用大尺寸试验装置及更多的制样用土.与大尺寸三轴试验相比,采用小尺寸三轴压力室,所需的试样较小,制样用土较少,且小尺寸三轴试验过程更快,试验成本更低.但采用小尺寸试样对粗粒土进行三轴试验时,往往得到偏小的抗剪强度参数,导致实际工程设计过于保守而不经济.为了降低试验成本,可以采用小尺寸试样进行试验,通过对试验结果进行修正来获得大尺寸试样试验结果,进而使工程设计具有良好的经济性.针对以上问题,本文对比研究了不良级配砾质砂混合物在采用去粗法前后制样试验所得的抗剪强度,提出了采用不同尺寸试样进行试验时对试验结果进行修正的方法及计算公式.