GNSS Algorithms For Deformation Monitoring Of High-speed Railway

Nowadays,the construction of China's high-speed railway is in full swing,bring enormous contribution to our country's social development.Due to the high requirement of the track,a small deformation may lead to serious consequences for the high-speed railway,so it is necessary to pay attention to the deformation monitoring.Compared to the traditional method by total station,GNSS can help improve the measurement accuracy,speed and efficiency,reduce interference during the measurement.Thus it can save a lot of manpower and economic cost,and a wide prospect can be expected.However,the RTK technology is unable to meet the requirement of the deformation monitoring of high-speed rail.So a suitable deformation monitoring program and appropriat e algorithm is very important in order to obtain high precision results.This paper find the most suitable method on the basis of in-depth understanding of the GNSS baseline algorithm,discuss the GNSS adjustment with constraint,and compile the program of ‘deformation monitoring of high-speed railway by GNSS',experiment is designed to verify the validity of the algorithm presented in this paper.This paper include the following aspects:(1)As the shortcomings of the traditional methods,a method for deformation monitoring of high-speed railway by GNSS is proposed.Base stations are set along the railway and rovers move on the track,to observe on each point,calculate the position with the distance and attitude constraints.(2)GNSS baseline processing is analyzed,and the resolutions for integer ambiguity are discussed in this paper,particularly,the LAMBDA method is analyzed in detail.Researches are done on the errors which may affect the accuracy of the short baseline solution.(3)The methods of GNSS network adjustment are discussed in this paper.It analyzes the way to add distance and attitude constraints to the adjustment.The model of attitude constraints are focused on,and the error equation of attitude is derived.The determination of weight matrix on different types of measurements is discussed.(4)A program named ‘deformation monitoring of high-speed railway by GNSS' is written.It can read data,eliminate errors,do baseline processing and network adjustment,output result files.(5)Several experiments are designed in this paper to verify the methods above.The improvement of the accuracy and stability of the result is checked by simulated experiment.Then the experiments on the railway show that the standard deviations in the East direction and North direction are less than 3mm,the maximum deviation is less than 8mm.