Research Of Resistant Coefficients And Reliability Of The Load-carrying Capacity Of The Pile On The Regional Site Soil

At present, the design of engineering structures is basically completelyupgraded from previous safety coefficient method to method based on reliabletheory of probability now. For the design method of geotechnical engineering,although our country initiated the geotechnical engineering reliability researchboom from the end of20th century to the beginning of21st century and thereliability theory had been applied in pile foundation of94specification, theresearch about application of geotechnical engineering reliability has been falleninto slow development stage in recent years, what’s more, the latest pilefoundation of08specification has also been restored to the safety factor designmethod of94version. The author thinks that the mean reason is that thevariability of geotechnical itself is too big, too many uncertain factors, and a lotof variable uncertain factors can’t be controlled, so that we want to get a wide range of geotechnical properties and draw up some structural specificationsbased on reliability theory like structure is quite difficult. But the author thinksthat we should not give up this advanced method based on the reliability theory,on the contrary, we should find out it through continual statistics and analysis.However, because of the complexity and particularity of geotechnicalengineering, the athor holds the view that we should adjust measures to localconditions for regional research and formulate different design parameters basedon the characteristic of the different areas of geotechnical characteristics toensure same reliability in different site soil condition. The author thinks thatwill be a feasible method.Combined with the existing engineering data in hand, this article studiesspace variation of soil of mingxiang campus of tyut, and put forward a designmethod of pile foundation of this field conditions according to these mutationssituation under this train of thought and requirements as follow: first of all, wetest continuous variation curves of friction and end resistance on different depthand site by CPT. Then, according to this curve, we can get some friction and endresistance date according to certain spacing.More importantly, according tothese data, we can calculate the variability of site soil. What’s more, we assumethat this data can stand for the mechanic property of the soil. Additionally, wecan calculate resisitant coefficients of pile for mingxiang campus by usingreliability method. At last,we verify that the resisitant coefficients we calculate is right according to the test report of single pile bearing capacity of mainbuilding of the library on mingxiang campus of tyut.So, this paper can draw thefollowing conclusions:1、There is only8.58%difference between the pile bearing capacity designed bythe reliability theory and test of pile foundation bearing capacity. This showsthat studying field soil mechanics variability by CPT is feasible, and using it toreplace the study of mechanical variability of pile is also effective.2、So long as we have CPT data,we can analyze the variability of soil and solvethe coefficients of the pile foundation design. This shows that the design of pilefoundation can use the reliability theory, and the difficulty is small.3、Traditional safety coefficient method doesn’t consider pile side frictionvariability、pile end resistance variability and ratio of pile side friction and endresistance, so the method in this paper is more scientific.4、Due to the CPT this paper use, this article concludes that the pile foundationdesign method can be used to design the pile by CPT and experience parameters.5、In this paper, the research methods and conclusions can serve as a researchmethod of regional soil and prepare to provide certain reference for the localcode.