Research On The Optimum Design Of Pile-Plank Embankment's Parameters In Expensive Soil Groud Based On Orthogonal Experiment Method

Pile-plank embankment is a kind of new-type of ballastless truck in high-speed railway, which is composed with the reinforced concrete plank at its upside and reinforced concrete piles, sub grade and ground at its downside. This new type synthesizes respective characteristic with the ballastless truck and the piles, owning the advantages of higher entirety and stability, less settlement, more convenient for construction, less maintenance and repair, etc. Therefore the piled-plank embankments are quite valuable to be extending in modern domestic and foreign railroads and highway construction. So far, the application of pile-plank embankment just starts in China, with no design code, and the pile-plank embankment is only adopted in the high speed railway, like Zheng-Xi, Jing-Jin, Sui-Yu railway in domestic projects application and fundamental research, not yet promoted to sub grade construction in expensive soil ground.In view of this, this author attempts to use pile-plank embankment to treat railway sub grade in expensive soil foundation. Based on the Yun-Gui railway for passengers'traffic DK631+500～DK632+700, the author optimizes the design parameter of pile-plank embankment in expensive soil ground, by using the orthogonal experiment method, which provide useful reference for the application of pile-plank embankment in expensive soil area. The results and conclusions are as follows.(1) Using the finit element software ANSYS to construct a pile-plank finite element model on expensive soil ground, this article calculates the settlement of pile-plank embankment under the situation that the bottom of piles is on the siol and that the bottom of piles is on the rocks separately, and analyses the characteristic of pile-plank embankment and soil's settlement. According to either characteristic of the settlement, the paper provides some suggestion for the design of pile-plank embankment on expensive ground.(2) Based on the study of foreign and domestic's research on the design theory of the pile-plank embankment, this article analysis the structure characteristic of pile-plank structure and mechanical characteristic of piles in the expensive soil ground. Therefore, the author provides the design method of pile-plank embankment on expensive ground. Based on overseas ballaseless truck design, the design control target of pile-plank embankment is also given in the article.(3) Based on the Yun-Gui railway for passengers'traffic DK631+500～DK632+700, the author design the pile-plank embankment in expensive soil ground and gives a variety of combination plan for pile-plank embankment's design parameters, by using the orthogonal experiment method. Then, the author calculates both the technical indicators and the economic indicators, in the basis of the combination scheme. Taking the technical indicator and the economic indicator into consideration, the author optimizes the design parameter of pile-plank embankment in expensive soil ground and gives the reasonable scope for each design parameter, which enable the pile-plank embankment to own great technical and economic advantages, under the background of yun-gui railway line for passenger's traffic. The conclusion is that span of the pile-plank embankment is 5-8m, thickness of the loading plate is 0.6～1m, pile diameter is 0.8-1.2m, number of span is 3～6.