Research And Engineering Application On Probabity Limit States Design Method Of Pilf Foundation

This thesis is based on a railway science research item under my management that was completed and identified.This thesis is on studying theories and analyzing experimental data. The main research includes: using the calibration method to proceed to the reliability calculations for piles in current railway bridges and culvert codes and making sure the reliability index is within its target; calculating with certain loading partial coefficients of piles; calculating with certain soil limiting resistance characteristic values around the pile' s outer surface, limiting resistance characteristic values at pile tips, which leads to variations in research; proceeding statistical analysis and variation research for the pile diameter of bored piles; developing study of soil property itself and its random application fields; and presenting the bearing capacity of the axial design formula of a probability concept for driven piles and bored piles.The research significance in this thesis consists in developing the research of the probability limiting state design method, making nowadays a permissible stress design method for railway bridges' transited limiting state design method, benefitting this in accordance with the probability design method in the bridges' upper part construction, attaining to an improved level in pile design, and serving the code reforme for railway bridges and culvert codes.This thesis research method applies to probability mathematics and physics principle which analyzes variability characteristics and regularity of load and bearing capacity, makes use of the current engineering experience in the safety and economics for looking for reasonable equilibrium, fixes the reliability index (corresponding to the probability of structural failure)of the engineering pile bearing capacity, so as to obtain the resistance partial coefficient for driven piles and bored piles in different soil horizons, and then adopts the formula to calculate bearing capacity using the partial coeffecient to express the limiting state design procedures , and attains to make pile design techniquea forerunner in its field, reasonable economics while applying safety measures and ensuring the quality.The research characteristics in this thesis are: attaining the firsthand data from engineering experiments; mastering the domestic and international developments and achievements in the related research through surveying and investigating; and studying the theoretical research of the bearing capacity of piles, resistance partial coefficient, reliability index etc. on the above research.The main work and results in this thesis are: analyzing the probability limiting state of pile's and on the data of static cone sounding (CPT) ; studying the resistance partial coeffient of driven piles and bored piles, then getting for total resistance , for a pile-side resistance , and for a pile-tip resistance , which are adopted to express a pile' s limiting bearing capacity formula;playing a key role in the application and in the normal reformation of piles' reliability in pile design.It is the first time to have a systematic research in the domestic fields to apply the self-correlation and stochastic field theory of soil property in CPT solving for the piles' limiting bearing capacity and reliability index. This kind of method is both convinient to make use of the advantage of the testing one of CPT and better to improve the piles' design level through it, and it can play an important part in the application of CPT in a pile's engineering.The normalized value of the limiting side resistance and the limited tip resistance of driven piles and bored ones was attained by the analysis on experiments and research of the theories.It is also the first time to analyze the potencial reliability of the bearing capacity of bored piles in the domestic and international realm. The practical formula of the bearing capacity and the charateristics of this type of poles are put forward based on statistical analysis. The results of calculation and analysi...