Study On Anchorage Depth Of The Hemi-Slope Pile

Hemi-slope pile is the anti-slide pile which is setting on the cutting slope or sharp decline of the road(railway road), the slip surface is very steep, especially the slip surface before pile is easy to form triangle body, anchorage segment is hard to meet the requirement of half-infinity body. In recent years, as the result of site conditions, topography, lithology and other factors limit, hemi-slope pile has a more and more application in slope protection and landslide treatment engineering. Little theoretical studies have been done on the designing of hemi-slope pile. In view of the research situation at home and abroad, it is an urgent task to research on design theory of hemi-slope pile.In this paper, the investigation research of hemi-slope pile is carried out, the relevant informations are collected extensively, including the failure cases and successful engineerings. On this basis, the design idea of the hemi-slope pile has been brought out, namely, increasing the length of pile anchorage segment to meet the requirement of the semi-infinity body, and the existing theories of anti-slide pile design calculation should be used on hemi-slope pile. This article focuses on studing the increase value of the anchorage segment, and the hemi-slope pile category, the principle and location of setting up the pile are also discussed in accordance with the stratum conditions. Some conclusions and results are as follows:(1) On the basis of the analysis of research data, hemi-slope pile is classified into four categories in according with stratum lithology around the anchorage segment, pile structure, and the failure mode of each category is discussed.(2) By discussing several key problems about hemi-slope pile design, four principles of setting up the pile are put forward. Based on the pile arranging principles, two methods to meet the requirement of the semi-infinite body are advised. One is increasing the length of anchorage segment and the other is designing a platform in front of pile with a width equaling to the sliding bed width.(3) According to the results of numerical analysis, Empirical formulas to determine the increasing length of anchorage segment are deduced, from which the fitting formula for computing the increasing length of anchorage segment AH and the platform width Ad are resulted in three types of soil which include dense clay, soft schist and common shale.(4) By reference to the existing formula for calculating the critical height of the elastic-plastic zone in front of the pile on the condition that the slipping surface is inclined, the curves about the law between critical height and the dip angle of the slipping surface in different strata are drawn respectively. Then the length of anchorage segment is increased gradually on the basis of these laws. Furthermore, comparisons are made between the results calculating with the two kinds of formulas.