The Engineering Application Research Of "Two Points Method" In The Line Horizontal Alignment Design

At present,the curve linear design of Chinese highway is mainly based on a method named "curve method".Therefore,it is widely used in the horizontal alignment of mountain high-grade highways and interchanges because of its advantages of adapting to terrain and ground objects.However,it is found that the "curve method" has defects such as a single line shape,flexible maneuverability,poor stochastic strain,and it is difficult to determine the end position and so on in practical applications.In order to solve the above problems and improve the curve method further,this paper designs the linear of the route plane based on the "two points method" in the specific engineering examples to study the engineering application effect of the method by combining theory with practice.This paper is willing to provide reference for the linear design of the route plane in the complex mountainous terrain.The research contents are as follows:(1)The design principle of the linear " two points method" of the route plane is expounded,which belongs to the category of the curve method.The innovation of which lies in estimating the other parameters of the line through the "two points" parameter,and then drawing the line shape,the parameters are automatically solved;The parameter calculation method of "two points method" and basic line combination are introduced by summarizing;Introducing the implementation designing steps of the "two points method" through the flow chart.(2)Considering the actual needs of the project,the calculation formula of the symmetrical basic curve when the known starting point parameter and the end point tangential direction are derived,and then the research object of the "two points method" is extended as the reverse and the same direction curve.Under the condition of known starting point parameters,a series of solution sets of the inverse and the same direction curve can be drawn by increasing the constraint condition(tangential length),and the calculation method of the S-shaped curve is improved.(3)This paper studies the preferred method of the "two points method" solution set and proposes a trial algorithm and an analytical method by combining the practical application of topographic maps and design experience.And analyzing the preferred methods ofsymmetrical basic type,asymmetric basic type,S type,oval type and switch-back curve by combining with the relevant requirements of the "Specifications".(4)Applying the “two points method” of the route plane linear design to the actual project-the mountainous hill area based on the "two points method" design software,and then the rationality and application process of designing linear parameters are analyzed,and the advantages and disadvantages of the method are summarized based on the designing result.(5)Applying the “ two points method ” of the route plane linear design to the engineering practice-interchange.By analyzing the difficulty about the linear design of the intersection plane,it is proposed to apply the "two points method" to the design principle of the ramp-line design with limited endpoints.It can be known from the research results that through the "two points",multiple feasible solutions of the inverse(same)flat curve can be obtained,the optimal solution can be automatically recommend,and the calculation method of the S-shaped curve is improved at the same time;the "two points method" can be applied to the planar linear design of the mountainous and heavy hills.This method is a supplement to the traditional curve method.The linear design result based on the "two points method" has the advantages of diversification and flexibility,and which is easy to coordinate with complex terrain topography;The "two points method" can be applied to the cross-line design of the interchange interchange,which solves the problem of limited end points in the interchange ramp.The "two points method" also improves the flexibility of the linear combination and the controling effect for the linear-shape direction,which is very suitable for the short-shaped interchange.