The Research On Application Of Using Power Test Techniques Of High Strain To Test Large Diameter Borehole Dabbling Pile.

On the characteristics of borehole dabbling pile, fundamentals of power test the pile, and physical basis, on-the-spot test, material processing and actual effectiveness of high strain power test the pile, this paper made an analysis and research, encircling the gist that the core techniques of using high strain to test the bearing strength of large diameter borehole dabbling pile.In this paper, the author found the particularity of using high strain to power test the large diameter borehole dabbling pile on the base of practice, and made a research of its core techniques. The results obtained had been applied to the testing course of piles of bridges in the expressway of Lang fang with satisfactory results. The engineering practice proved that it is complex and difficult to use the power test techniques of high strain to test large diameter borehole dabbling pile. However, it can be used to test the bearing strength of one engineering pile by analyzing its core techniques and taking rational methods. Therefore, we can use high strain to test the bearing strength of large diameter borehole dabbling pile to partly instead of dead load experiment with saving both time and money. At the same time, high strain is represential for the pile as the supplement of dead load experiment.The author analyzed the results of high strain test by three steps. First, the author collected and collated the acting parameters of pile-soil in certain geological condition to guide the fitting analysis to come. These parameters come from a large number of good results of high strain, especially results compared with dead load experiment. In the second part, the limit frictional resistance of the earth around pile and the limit bearing strength of the earth of tip pile in different stratum units were counted and calculated, using in the designing of piles in the similar execution as local empirical data. In the third part, the author counted and analyzed the bearing strength behavior of large diameter borehole dabbling long pile (d≥1200mm, l/d>30) under designed-load conditions, and got results that resistance of pile side occupied over 80%of the whole with main effect of bearing strength.