Research On Grouting Material And Its Performance Under High Geothermal

In recent years,the grouting reinforcement technique was gradually applied to many fields of civil engineering,especially in the subgrade treatment,surrounding rock reinforcement,water prevention of mines,coal mining and other projects were used extensively.Research for various grouting materials were also becomes more mature.However,with the rapid development of the national economy,the construction of highways,railways and tunnels in the western region is accelerating,and the number of long and deep tunnels has been increasing,at the same time,the depth of mine exploitation has been increased,which will affect the performance of the grout in the grouting process and after grouting.Therefore,it is very important to study the grout properties of grouting material under different temperature conditions.Based on the simulation environment of high temperature indoors,having used cement,bentonite,fly ash and slag as grouting materials and polycarboxylate superplasticizer as admixture to test in this paper.The properties of different ratio of grout at different temperatures were studied,and the durability of the best ratio of grout at different temperatures was researched.In addition,the model test was adopted and the relationship between diffusion distance and temperature was obtained.The main contents are as follows:(1)The properties of cement-bentonite grout at different temperatures(20?,40?,60?,80?),such as the setting time,viscosity,syneresis ratio and compressive strength,and their changing trends were studied.And the reasonable ratio of grout were obtained from combination of 3% bentonite when water cement ratio was 0.8,and combination of 6% bentonite when water cement ratio was 1.0,and combination of 9% bentonite when water cement ratio was 1.2.(2)On the basis of the above,the orthogonal test was designed through mixing fly ash and mineral powder,add polycarboxylate superplasticizer,and the properties of each ratio at different temperatures were tested.The effects of water-cement ratio,polycarboxylate superplasticizer,fly ash and slag on the performance of grout as well as the change rule of the setting time,viscosity,syneresis ratio and compressive strength of grout with temperature variation were studyed.And the optimal composition of grout was determined from a combination of 0.15% polycarboxylate superplasticizer,0% fly ash and 30% slag when water-cement ratio 0.6 / bentonite 0% at 20?,40?,60? and 80? by matrix analysis method.(3)The trend of the chloride ion electric flux,resistance to sulfate attack and carbonate erosion resistance of grouting concretion body with temperature were researched through tested for durability of the optimal composition of grout at different temperatures.(4)Grouting test of the optimum ratio of grout was done at different temperatures(20?,40?,60? and 80?)by using the oval fissure grouting model.The variation trend of the diffusion distance,the grouting amount,the grouting time and the pressure along the path is obtained,when the grouting pressure is certain.Moreover,the grout filling effect is good by the obserwation,and it can achieve the effect of grouting reinforcement.