Experimental Study On Audio Frequency Vibration Grouting In Fine Silty Sand Layer

Fine silty sand layer due to small size and poor stability,so the grouting treatment work,has been one of the hot spots in engineering research.The use of high frequency vibration and high pressure to improve the diffusion of slurry is a new method of grouting.Therefore,the new grouting method is researched in this article.Firstly,the rheological properties of the slurry were investigated.Considering the diffusion model of the grouting slurry in the formation,the vibration grouting model was established based on the audio vibration drilling mechanism.Secondly,aiming at the shortcomings of the current indoor experiment of vibration grouting,a new test platform for vibration drilling is developed,which includes vibration generating device,transmission rod,support device,sand box and slurry pipeline.The test platform can realize the change of vibration frequency,exciting force and vibration time,and adjust the pressure and flow rate of the slurry.Thirdly,according to the main engineering properties of the fine sand strata,the experimental grouting slurry was prepared according to the physical and chemical properties.Subsequently,a static pressure grouting test was carried out to determine the appropriate grouting pressure for the test sand and as a contrast experiment for subsequent tests.Finally,carry out the simulation experiment of audio vibration grouting,and the following conclusions can be drew:(1)The vibration frequency of the vibration source is more closer to the natural frequency of the sand layer,the larger the injection amount and the diffusion radius of the slurry becomes,and the better the grouting reinforcement effect is.When the vibration frequency is higher than natural frequency,the effect of vibration impact on improving grouting environment is not obvious,on the contrary the hole gap is enlarged due to the vibration force,especially when the bureid depth of the drill pipe is shallow,it is more likely to produce the bleeding phenomenon,which is not conducive to the grouting effect.Only according to the actual working conditions to choose appropriate frequency,it is possible to achieve high quality and efficiency of the engineering construction.(2)The magnitude of the vibration force on the audio vibration grouting effect is not obvious.Under the proper frequency vibration action,the grouting effect does not change clearly with the variety of the exciting force.(3)At the initial stage of the vibration action,the slurry diffusion rate grows fastly and the slurry consolidation becomes larger.With the extension of the vibration time,the slurry diffusion radius will gradually increase,but the speed will gradually cut down,the final rate approaching to none.In conclusion,the vibration frequency is the key factor which determines the grouting effect.Aiming at different fine silty sand layer,adjust the vibration frequency can effectively improve the layer injection ability with high grouting pressure,and enhance the slurry injection,expand the diffusion radius of the slurry,increase the volume of slurry consolidation.