Study On Grouting Material Performance And Grouting Simulation Experimental In Water-rich Sand And Gravel Stratum

With the deeper and deeper of the subway construction,it is is becoming more and more significant for the groundwater put impact on the construction of the project,especially for the sand-pebble strata in northern China.Because the sand-pebble stratum has uneven particle size,high permeability coefficient and small compressibility,it is easy to occure the inrush and collapse problems,which is caused by the seepage of groundwater during the construction process.And because of the restrictions of policies and equipment,direct precipitation has become extremely difficult.Therefore,it is feasible to use grouting to strengthen the formation and stop the water.However,the complexity of the stratum,the pertinence of grouting material selection and the lack of grouting simulation test under dynamic water conditions make the grouting process of sand and gravel formation have more problems in terms of mechanism and engineering practice.Therefore,the research on the selection and performance of grouting materials for water-rich sand pebble and the improvement of physical and mechanical properties of soil after grouting have important engineering value and practical significance.This paper combines a subway station,which needs to cross the water-rich sand and gracel stratum project,in Beijing,and carries out the grouting test research of sand pebble.It combines theoretical analysis,geotechnical test,outdoor simulated grouting test with actual engineering.Study the grouting effect of different materials under dynamic water conditions.For the best grouting material and the best grouting effect,the void filling rate of the soil reaches 92%,the compressive strength is improved,the permeability coefficient is reduced by 4 orders of magnitude,and the strength of the soil after grouting is improved.That is to say that the water-rich sand pebble soil is reinforced,which solves the problem of poor grouting and water-stopping reinforcement in the water-rich sand pebble stratum.By analyzing the microstructure of composite soil,comparing the injectability of different materials in sand and gravel stratum,and analyzing the economic benefits,the research results can provide reference for similar projects in the future.