Research On The Track Irregularities Survey Theory And Relevant Adjustment Technologies Of HSR Track

With the completion and operation of HSR (high speed railway), the problem oftrack irregularities survey and control is an emerging challenge for Chinese railways.In present, the survey and control of inner geometries to HSR track is realized bymeans of outer geometries survey. That usually leads to the imbalance between costand efficiency for the maintenance. This paper studied the irregularities of ballastlesstrack, discussed the problem of HSR track irregularities survey and control. As thefollowing:(1)Control accuracy of absolute survey method in fine adjustment for HSRballastless track. In present, our fine adjustment of HSR ballastless track irregularitiesis based on the method of absolute survey, which is based on Electronic Total Station(ETS). This method controls the inner geometry by means of surveying the outergeometry, so it is naturally that this method is not compatible well with the traditionalconcept of track irregularities. In this paper, a discussion was drawing out whichabout the error of absolute survey. Then an analysis of precise adjustment controlaccuracy is present from mid-chord offset measurement model.The results oftheoretical analysis and relevant experiments proved that the adjustment accuracy ofirregularities mainly depends on angle measurement accuracy of ETS, and only withhigh accuracy ETS will this method could meet the accuracy requirements ofirregularity adjustment for HSR ballastless track which is within±2mm.(2)Discussion about mid-chord offset method and offset differential method.There are two methods for alignment and profile irregularities evaluation of HSRballastless track, i. e. mid-chord offset (MCO) method and offset differential method.MCO method has been applied in track survey field widely. As a survey method fortrack irregularities, the theoretical value of MCO method has received less attentionfor its magnitude frequency characteristics, while the application of offset differentialmethod was limited due to its dependence of absolute survey. On this basis, a universal algorithm for chord deflection offset was established which is based onshort chord MCO data. The result of computer simulation has shown that: theuniversal algorithm could meet the accuracy demands of5m/30m bias-chord offsetdifferential check. By means of frequency characteristics and error characteristicsanalysis, this paper argued that: contrast with offset differential method, MCOmethod has some characteristics in the same chord length, e.g. zero phase shifting,richness of irregularities information, location convenience and characterization ofdynamic properties. Not only that, the MCO method is able to extract the informationof long wave irregularities with extended algorithm. The universal algorithmestablished in this paper should provide a new method for the measurement of5m/3mand150m/300m check in HSR survey. Moreover, harmonic analysis suggest that150m/300m check method has the competence of amplitude measure for irregularitiesin60m or100m wavelengh despite of phase difference. But for harmonic waves inother wavelength, this method can lead to distortion of amplitude and phase. Hence,this method does not apply to long wave irregularities control for HSR.(3)Feasibility of involute methods in HSR curves realignment. A matrix modelof string lining method is established. From its conditional number, the behavior ofstring lining method is discussed. Adopted uncertainty theory, the relationship of errortransmission between existing ordinates and desired ordinates is subsequentlyquantitative analyzed. Research shows that: String lining method is sensitive to thedata disturbance owing to its ill-conditioned operational matrix; On account of theaccumulate operation in involute algorithm, the error of throw and irregularity tendsto increase with station numbers, so this method is only suitable for short-rangeoperation; In view of the ordinate tolerance of HSR curves, string lining method doesnot apply to HSR maintenance and HSR curves should realigned with other methods.(4) Numerical solution of fine adjustment for HSR track. The conventionalmaintenance technologies based on outer track geometry exists some problems ofserviceability for HSR ballastless track in consideration for its special constructionand high smoothness requirement. To guarantees the smoothness of HSR track, acomputing method of track realignment on the basis of track irregularities is proposed. By means of mid-chord offset model, this method establishes the vector models oftrack irregularities based on the inertia locus which track inspecting instrumentmeasured. Aiming at the recovery of high smoothness, a SOR iteration algorithm hasbeen constructed for the numerical solution to realignment value. Theoretical analysisindicates that this method is convergent, and the initial state of ballastless trackobjectively ensures convergence rate. This method has been applied to fineadjustment of ballastless track in several HSR. Kinematical survey results proved thatits adjustment quality could meets the requirements of acceptance standard for trackplanning works, which is comparable to absolute adjustment.(5) Procedure of long wave irregularities adjustment.Longwave irregularities ofHSR track is an increasing concern in many maintenance depots as the increasing ofoperating speed. In present, the adjustment of longwave irregularities is based onabsolute measurement, so it is inefficient and not fit for the routing maintenance ofHSR. Firstly, this paper introduced the measurement technologies for longwaveirregularities. And then an adjustment method based on L-0track survey trolley ispresented. Finally, key points of adjustment execution have been given. Theengineering trail in existing HSR rail proved that this method could meet therequirements of rapid adjustment and routing maintenance.