Research On Correlation Of Hammering Energy Test And Hammering Number In Conventional Power Penetration Test

The increasing risk of natural hazard is becoming an inevitable threat to the sustainability of the society,economy and environment.China is one of the countries that suffer the most from natural disasters in the world.At the same time,the current state of the country basic engineering construction is prevalent,and new problems and challenges continue to rising that disaster prevention,mitigation and disaster relief technologies become needed.As an important part of engineering construction,engineering survey is a key to evaluate the quality of the engineering site and directly determines the safety and cost of engineering construction.In-situ testing technology is an useful tool in geotechnical engineering survey,which is to test the physical properties of the soil in the original state without disturbance or slightly disturbed.Dynamic penetration and standard penetration tests are commonly used in engineering penetration testing practice.Energy transfer ratio is a critical index to measure the hammering efficiency during penetration.Foreign countries generally carry out on-site measuring of this index so as to correct the hammer blow counts in the penetration test.In the Chinese codes,the impact energy transfer rates of hammer drops in the penetration test are not considered,that it is difficult to compare the field evaluation methods based on the blow counts of penetration tests with other countries.In this thesis,by selecting different test sites in Chengdu plain and The Sichuan-Yunnan Regin of CSES,different types of dynamic penetration tests and standard penetration tests are carried out,and the energy transfer ratios of hammer drops are measured by the new energy measuring equipment called Pile Dynamic Driver(PDI).Testing the hammering efficiency can be used to evaluate the energy transfer stability of the routine penetration devices,and to explore the correlation of blow counts obtained by different types of penetration apparatuses.The main work and conclusions are summarized as follows:1.Through the hammer energy measurement of different types of dynamic penetration tests on site,the distribution characteristic of hammer energy transfer ratios of different types of dynamic penetration test is discussed,and the correlation between hammer energy transfer ratios with respect to depth is analyzed.2.The energy calibration method and the real measured hammer-dropping comparison method are used to study the correlation between the hammer numbers of different types of cone dynamic penetration tests,and the results obtained by the two methods are compared.The results indicate that the results obtained by the two methods keep a well consistency.3.The hammer energy transfer ratios of the standard penetration test was recorded by the energy tester,the stability of the hammer energy transfer rate of the standard penetration test is studied,and the correlation between the standard penetration test hammer energy and the test depth was analyzed.4.By comparing the hammering counts obtained by cone dynamic penetration tests and standard penetration tests,the correlation between the hammering numbers of the two penetration tests is studied,and the conveting relationship between the two is discussed preliminarily.