Research On The Load-bearing Characteristics Of High Piers Double-row Piles In Steep Slope

With the further development of western region in our country, lots of highways are being constructed in steep ravines in the mountain areas. And with the strengthening of consciousness about environmental protection, people put forward higher requirements to the excavation and slope putting of highways. So, Pile pier column type becomes the main structure of highway bridges. High piers of double row pile,as a new pile column structure,is being extensively used . High piers of double row piles have some connection between the up-middle beams, and are located in high and steep slope, which make their stress state very complex. Besides, the current specification lacks relevant content for designing. In order to overcome problems of these pile foundations existing in designing and calculating, this paper makes an exploratory study on the bearing mechanism of high and steep cross-sectional slope section high piers of double row pile with various research methods such as theoretical analysis,numerical simulation,model test,integrated computation and so on, according to the project"Research on the technology of the designing and construction of the pile pillar type bridge under the condition of the high and steep slope"of the Ministry of Communications. Based on the investigating of a large number of domestic and foreign references, this paper makes a further study on the following problems.Firstly, the stability of the high and steep slope is analyzed, and definitions of domestic scholars about the high and steep slope and the rock (soil) mass failure criterion are described, which provide a theory basis for stress and fem analysis of the pile. Calculation methods for the safety factor of the steep slope stability in different form of landslide are also introduced. Then this paper studies how the imbalance thrust force effect on the front pile and back pile, which provide theory for the stability of slopes.Secondly, this paper uses ADINA, the finite element calculation software, to calculate and analyze the high piers double-row piles in high-steep transverse slope and researches it from loading sequence, the modulus of elasticity of soil, and the changes of pile body. The result shows that the loading sequence has a little impact pile foundation when the pier is not high. Thirdly, this paper studies the load-bearing characteristics of high piers double-row piles in high-steep transverse slope by the means of model test. The pile's moments is calculated out though strain of the two sides of the pile and the displacements are tested by dial indicators. The research shows that the displacements increases by height and the moment of rock-socketed is almost zero.At last, the load-bearing characteristics of high piers double-row piles in high-steep transverse slope is studied and analyzed. And then we deduce the calculation formula elastic compression,the pile's moments,the thrust force under imbalance,the vertical load and horizontal forces and so on with the finite element method. It has a difference less than 10% between the results calculated by the two methods and the experiment, which shows the two methods are feasible.