Development And Application Of Centrifugal Mini CPT Equipment

Test method which is used to obtain soil parameters in geotechnical engineering of soil test laboratory can be divided into situ test, laboratory test and model test. These three test methods have certain shortcomings. Centrifuge model test is the combination of laboratory test and model test. And it combines with the size effect under speed centrifugal acceleration of centrifuge. It can make stress levels of small-scale model reach the similar stress levels with the prototype and make stress, displacement, development of plastic zone and deformation destruction process of model in the experimental procedure close to the same with experimental prototype. Through this way, the deformation and failure mechanism of the full-scale model dimensions can be simulated. So this model is widely used in geotechnical engineering problems. As a situ test technology, static sounding technique has some advantages such as convenient, fast and high efficiency and so on. It has become one of the key research methods in the research of geotechnical engineering problems.This paper combines the situ test technology with centrifuge model test. By developing micro static sounding equipment which can be used to centrifuge model test, this paper gets on centrifuge model static cone penetration test of sand model and clay model. The test researches the impact of the dry soil density, moisture content and other factors for specific penetration resistance, tip resistance and side friction and analysis the variation of specific penetration resistance and tip resistance with penetration depth. The studies contain the following.1) Develop the Micro static sounding devices and related operating equipment that can be used for the development of centrifuge model test: develop micro static sounding instrument used in laboratory and ancillary equipment operation on multifunction 50g-t geotechnical centrifuge in Tsinghua University.2) Test and verify the reliability of the sets of equipment by getting on basis test of centrifugation field static sounding model. The results show that the sets of equipment have high reliability and repeatability.3) Research the test mechanism of sand model under centrifuge model static sounding by carrying static cone penetration test of sand model and controlling the model dry density, the test gravity conditions, model consolidation time and other factors. At the same time, this paper studies the impact of these factors on the test results.4) Research the test mechanism of clay model under centrifuge model static sounding by carrying static cone penetration test of clay model and controlling the model dry density, water content, the test gravity conditions, model consolidation time and other factors. At the same time, this paper studies the impact of these factors on the test results.