| Shield method has been widely used in the construction of cities' metro and the major underwater tunnel.However,It will always be a problem troubled experts and scholars that formation damage and deformation settlement of surface caused by shield construction.Synchronous grouting is an important means to reduce the loss of formation,to control the release of formation stress and stratum deformation,and it is the necessary and the key process of shield construction.At present,the research on the synchronous grouting of shield tunnel is mainly focused on the numerical simulation,and the selection of grouting parameters is too dependent on the personal experience of engineers and technicians,and it is still not clear that the deformation law of grout when it's in the process of hardening affected by grouting pressure.Therefore,according to the new type of single component inert grouts adopted by a shield tunnel in soft soil layer in Shanghai and Suzhou area,the article carried out the optimization experiment of the ratio of grouts materials,on this basis,the influence of stirring time and stirring mode on the performance of the grouts was also discussed,and developed a grouts shrinkage deformation device through the analysis of the stress state of grouts,then studied the shrinkage deformation law of the new single component inert grouts under grouting pressure.The main research contents are as follows:(1)Referring to the formula of new type of single component inert grouts used in Shanghai and Suzhou,by using the uniform experimental design method to optimize the proportion of synchronous grouting material,and providing a scientific basis for using appropriate grouts ratio.The specific effects of various components of the slurry on the construction performance are discussed by means of multiple non-linear regression.(2)On the basis of the study on the variation of the slurry performance with the composition of the slurry,In order to meet the requirement of strength R28>1.0Mpa,the MATLAB SQP optimization method was used to optimize the proportion of new single component inert slurry.The results are as follows:Hydrated lime 120g,fly ash 574.4g,bentonite 203.4g,sand 1015.3g,water 684.7g,water reducer 5g.(3)Studying on the effects of stirring time,stirring speed and stirring type on the properties of the grouts,high speed stirring(800r/min)compared to the low speed(200 r/min)mixing state of slurry consistency value increased about 10%,the bleeding rate decreased 30%,compressive strength of 28d decreased by 10%.(4)Developing a grouts shrinkage deformation device,and systematically study the deformation law of grouts when it grouting into shield tail void,then discussing the influence of different grouts type,different grouting pressure and different stratum foundation on the deformation law of grouts.The volume shrinkage of slurry increases with the increase of time,and the volume shrinkage rate decreases with the same grouting pressure;Compared with the clay soil,the volume shrinkage deformation rate is faster in the sand soil,and the final shape is larger. |
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