Theory Of Geotechnical Shaking Table Test And Its Application In Study Of Dynamic Response Of Buried Pipeline

Large city in west-south area of China mainly located in high seismic intensity area,which suffersfrom earthquake damge frequently in recent decades. Therefore, it is important to develop the seismic design methods of key structures. Shake table test is an important method to study seismic response of engineering structure. In recent years, numbers of research achievementsfor techniques of shake table testhave been applied in scientific research and engineering practice.However, some questions such asresonable similarity relationbetween model and prototype objects, and development between analyses techniques and experimental technique remain uncoordinated.While lots of large shake table test equipements with advanced technology have been built and put into use, the design and analyses theory of shake table test are still insufficient.Therefore, a systematic investigation of geotechnical engineering shake table test theory has been performed to study the similitude design techniques, model soil and model bedrock designmethod. Based on the theory of respective dimensional analysis, a new similitude design theory for complex model test is developed,which includesmethods on designing model material of soil, rock and structure used for shake table test.The proposed design theory are verified by a shake table test of underground pipeline under uniform seismic excitation. The verification is presented by comparing the strain of the underground pipeline from shake table test results withresults calculated by design codes. The theory derivation and verification work was carrinng out in follow procedures:Firstly, respective dimentional analysis hadbeen developed. Based on this innovative method, a newsimilitude design method for complex shake table test was established. According to the new method, shake table test for buried pipeline under uniform excitation was designed, then the functional equation of dimensional analysis and scaling relations for primary variables that belong to model soil, model structure and input motion were derived. Asfunctional equationseparated, the important degree of every variable can be distinguished.Secondly,study on nonlinearity, hysteresis and accumulation behavior of model soil was proposed, which showed that the key similarity factors of model soil was dynamic shear modulus ratio with shear strain. Then, comparion among different empirical method was performed. The reference strain in Stokoe model was selected as the control parameter of relationship between dynamic shear modulus ratio and shear strain. Based on aboveresult, model soil design test wasperformed, and the ratio of clay and sand was determined asl:1.5 and the ratio of water was 14% respectivly. After that, a judge system of similarity degree was determined, which includes the correlation coefficient, similitude ratio of reference strain, uniformity coefficient and coefficient of curvature. By using this system, the similarity of model soilsurrounding buried pipeline can be well ensured.Thirdly, bedrock material was determined based on the similaritybetween model and prototype material.The control parameter for this case was selected as shear wave velocity.Then, by carring out orthogonal experiment, a new similar material of soft rock was obtained. And the sensitivity and influence on density, initial shear modulus and reference strain of every ingredient wasanalyzed. Furthermore,severaldynamic triaxial tests for the similar material of soft rockwereconducted to study its dynamic behavior.Finally, after preparing similar material of soil and bedrock fulfill proposed respective similarity theory,shake table test was conducted. The test studied the dynamic response and torsional behavior of buried pipeline under uniform excitation.By comparing the results of calculated by design codes against shake table test, the verification and discussion of proposed respective similarity theory were proposed.The similarity design theory of shake table test for geotechnical engineering presentedin this dissertation can promote the development of shake table test design technique, and remit the current develop lagging between design method and test equipment. The proposed shake table test of underground pipelines can provide important design suggestion foroil-and-gas pipeline and city water supply system. The works of entire dissertation are significant in reliefing economic losses caused by large earthquake and increasing security of energy and lifeline structures.Besides, it may provide useful suggestion for promotion of the earthquake-resistant level of geotechnical engineering in our country.