Study On Calculation Method Of Vertical Bearing Capacity-settlement Of Single Pile Suitable For Bangladesh

As a type of pile foundation,bored piles are widely used in large-scale construction projects at home and abroad to bear the upper load.Pile foundation design codes are different at home and abroad,so there are many disputes between Chinese and foreign parties on the design methods of pile foundations in large-scale construction projects abroad.In order to be in line with international standards,Chinese designers need to master the design methods of pile foundations in various countries in detail and clarify the reasons for the differences in the design methods of pile foundations in various countries.After this,designers can obtain pile foundation design schemes approved by both Chinese and foreign parties on foreign construction projects.This article relies on the subject "Research on the bearing characteristics,calculation methods and design optimization of pile foundations based on Eurocodes",based on the in-depth analysis of the calculation methods of pile foundation bearing capacity in Chinese Code,British Code,European Code,American Code,Bangladesh Code and German Code,for long bored piles and short and medium bored piles,by comparing the pile foundation bearing capacity calculated according to various codes with the results of on-site static load tests at home and abroad,study the relationship between the relative error of the bearing capacity of a single pile calculated according to the standards of various countries.Subsequently,using linear regression analysis and mathematical statistics methods,by comparing and analyzing the results calculated according to the German standard and the static load test p-s curve,corrected the displacement limit recommended by the German code.Furthermore,a simple method for calculating the ultimate bearing capacity-settlement of a single pile based on the German code is proposed.Research indicates:1.The main reason for the large differences between the Chinese design results about pile foundation and the foreign consulting results in large-scale construction projects abroad is:China and Europe and the United States have different standards for determining the ultimate bearing capacity and maximum settlement of the test pile based on the p-s curve of the static load test.2.It is more reasonable to calculate the vertical bearing capacity of the pile foundation by using the Chinese railway bridge and culvert code for long bored piles and calculate the vertical bearing capacity of the pile foundation according to the German standard for medium and short bored piles.3.Transform the displacement restriction condition srg=0.5·Qrg(MN)+0.5≤3(cm)recommended by the German code to srg=a·Qrg(MN)+b≤c·D(cm).According to the collected p-s curve of the site static load test of 37 domestic bored piles,use linear regression analysis and mathematical statistics methods to correct the 3 parameters in the deformed displacement restriction condition.The corrected result is displayed as followings.When the pile tip is in cohesive soil,the displacement limit formula suitable for long bored piles(pile diameter D=1.0～1.5m)is srg=0.0561·Qrg(MN)+0.875≤0.011·D(cm).When the pile tip is in non-cohesive soil,the displacement limit formula suitable for long bored piles(pile diameter D=1.0～1.5m)is srg=0.0561·Qrg(MN)+0.875≤0.016·D(cm).4.According to the collected field static load test of 34 piles with diameter D=1.0～1.5m at home and abroad,calculate the ultimate bearing capacity and maximum settlement of a single pile according to the formula recommended by the German code and the formula proposed in this article.The ultimate bearing capacity and maximum settlement calculated by the two formulas and the ultimate bearing capacity and maximum settlement determined by the on-site static load test are compared and analyzed.It is found that the ultimate bearing capacity calculated by the two formulas is not much different.And when the formula proposed in this article is applied to domestic test piles,the maximum settlement obtained is relatively close to the maximum settlement of a single pile determined by the static load test,and the difference between the two is-10.97%.