Study On The Mechanical Parameters And The Method Of Rockmass Classification Of Sandy Surrounding Rock Of Tunnel

Chinese Infrastructure now is coming through a cosmically development period. Varieties of transportation projects such as express high ways, high speed railways, city underground are under construction. Technical problems related to security, environments, economy and humanity are increasing in tunnel and underground engineering. Accordingly, rules and regulations, which are made to guarantee the solution of these problems, are becoming strict. Many technical criteria in using are requiring updating and perfecting. Because of its qualitativeness and subjectiveness, the criteria of surrounding rock mass classification for the soil tunnel and underground engineering in China are far from accuracy. It is in an urgent need to advance an explicit and user- friendly index system of soil surrounding rock mass classification of tunnel which can comprehensively show the stability of surrounding rock. Thereby, aiming at the solution of major problems in rock mass classification of sandy tunnel, this thesis makes a systemic research on rock mass classification of sandy tunnel and arrives at conclusions as follows:1. A new and more practical index system of sandy surrounding rock classification is established by great quantities of investigation and statistical analysis of domestic and overseas information. The method of acquiring each index of system is also introduced.2. Effect of the index value combination of sandy surrounding rock mass classification on the index of the sandy rock's mechanics is studied and the method of assessing the value of the mechanics index by using the index of classification is educed based on the study on the stability of the sandy surrounding rock, indoor soil experiments, statistical method and data graph method. Values of subsections of classification index are grouped.3. The definition of the sandy surrounding rock basic quality (SBQ) generally reflecting the mechanics capability of the sandy surrounding rock is advanced. Based on the results of soil experiments, the quantitative expressions of forecasting SBQ by the basic indexes value combinations and the values of the physical mechanical indexes by SBQ is received by studying on the relation between them by using statistical method and data graph method.4. The values of subsections of classification index are grouped and using sandy surrounding rock basic quality (SBQ) as benchmark to group the stability of the subsections. Based on the theory of the G.Kirsch's formula about excavated span of tunnel and the displacement around the tunnel in elasticity mechanics the stability of sandy surrounding rock is produced by numerical value simulation in the method of Fast Lagrangian Analysis of Continua(FLAC) and the similitude model tests.5. The combinatorial qualitative applied criteria of the classification is gained by comparison between each subsection of sandy surrounding rock's basic steady excavated span and the academic standard of surrounding rock mass classification provided by the active criteria; According to the results of the indoor soil experiments, the differentiate benchmark of the stability classification by using SBQ is put forward and the integrative quantificational applied criteria of the classification is produced.6. The values of the physical mechanical index of all levels of the sandy surrounding rock is gained by indoor soil experiments and great quantities of data investigation.7. A system of structural design parameter for all levels of sandy surrounding rock of the double lane highway tunnel is established by analysis and investigation of domestic and overseas information, and the method of numerical value simulation based on the research results of the stability of the sandy surrounding rock of the double lane highway tunnel.8. The validity of the method of the classification of the sandy surrounding rock is validated based on the investigation information.