Study On The Applied Credibility Of Under-reamed Pile In Shenzhen And Its Peripheral Regions

As the under-reamed pile is a new pile-type, its applied time is not very long in Shenzhen and its peripheral regions, a lot of developers (investors) have very big worry to it. This text with the engineering practice of the Shenzhen Zhanlian Base Architecture Engineering Co.,Ltd.(Hereafter referred to as Zhanlian Company) for background, in the foundation of checking a great deal of cultural heritage, the author has launched the research of under-reamed pile's applied credibility in Shenzhen and its peripheral regions, has made the following research results:1, Zhanlian Company has improved and summarized the technique parameters of the extension head and has made this kind of pile-type suiting to local conditions after importing under-reamed pile's construction technique, has carried on the innovation to the construction craft, such as adopting reverse circulation drilling and cleaning pore etc, that have guaranteed the under-reamed pile's applied credibility to some extent after adopting these technique measures.2, The author having adopted a more advanced ultrasonic large diameter pile-hole detector currently — CDJ—1 examination instrument (Hereafter referred to as the CDJ—1 examination instrument), has carried on the examination to hole completion quantity, that has insured the holes' quantity, and also has laid a good foundation for guaranteeing the whole pile-foundation project's quantity.3, The author has put forward three factors that affecting under-reamed pile completion quantity and adopted the homologous measures, has set up pile-breakage fault tree for bored(bottom enlarged) concrete piles applying Safe System Engineering Theory, and has carried on the qualitative analysis towards pile-breakage fault, these conclusions drawn by analyzing have certain leading meanings to the engineering construction.4, Adopting dynamic low strain test and pile sample digging test, theunit of the examination has carried on the examination to under-reamed pile completion quantity, the two methods being used very commonly currently, the checking results are all qualified, and having verified the dependability of the under-reamed pile's quality tentatively.5 > Adopting the most ocular and reliable method at present— static loading test, the unit of the examination has measured the under-reamed pile's bearing capacity, the examination results are all qualified, in order to verify their bearing performance further, a GM(1,1) model has been established by Gray Prediction Theory and using observation data of loading tests for under-reamed piles, the author has made correction to the original model, and has predicted the biggest settlement, the results show that the under-reamed pile's bearing performance is better than the checking result.6^ The author has explained the under-reamed pile's technologyn economic advantages, and has raised an example to verify that, greater technology^ economic advantages have been founded for under-reamed pile when selecting pile-types.The textual research results show that: the under-reamed pile's application is reliable in Shenzhen and its peripheral regions, if condition permitting, its application should be enlarged.