| Underground coal mining faces special environments such as high stress,extreme temperature,large deformation,broken soft rock,water seepage,harmful gas,etc.the support performance of underground roadway is particularly important.The concrete used for underground support requires a large amount of sand and gravel materials.In recent years,the price of sand and gravel materials has increased year by year.The concrete mixed with natural sand has excessive performance and low economy,which is not suitable for coal mine production,The shortage of sand and gravel materials and the increase of cost have become the main obstacles to the application of concrete in coal mines.As a substitute of river sand,desert sand in Maowusu Sandy Land in Northern Shaanxi can play the advantage of adjusting measures to local conditions,reduce the mining cost per ton of coal and improve production efficiency;The research on the engineering applicability of desert sand in Maowusu sandy land can solve the dilemma of building sand in the actual production of coal mines,and fundamentally alleviate the contradiction between the insufficient supply of natural sand and the sharp increase in the amount of sand used for filling and supporting in coal mines.It provides a research basis for the energy development in Western China to promote industrial upgrading.Therefore,this paper mainly studies the performance of desert sand mining concrete:(1)Taking Mu Us desert sand as the research object,this paper studies the relevant engineering indexes of desert sand used in construction sand,compares various physical performance indexes and characteristics between desert sand and river sand,evaluates the similarities and differences between desert sand and river sand in the requirements of construction sand,and draws a conclusion that except for the small particle size,desert sand has no difference in other chemical components from river sand,the content of harmful substances is very small,and the roundness is better than river sand(2)Desert sand is mixed into ordinary concrete at the replacement rate of 0%,10%,20%,30%,40%,50%,60%,80%and 100%river sand.The compressive performance and workability of conventional concrete and other indicators related to the service environment of mine concrete are tested,and the pore and fine view morphology are analyzed to evaluate the appropriate mixing ratio of desert sand and the performance difference between mine concrete and ordinary concrete with appropriate amount of desert sand.The test results show that the performance of desert sand mining concrete is better than that of ordinary concrete when the content of desert sand is about 30-40%.(3)Through the difference between desert sand and river sand and the test results between desert sand mining concrete and ordinary concrete,this paper comprehensively analyzes the relationship between compressive strength and porosity of desert sand mining concrete under the conditions of high pressure and rich water underground,and compares the advantages of porosity and strength of ordinary concrete.This paper takes desert sand mining concrete as the research object,based on the abundant desert sand resources in Maowusu Sandy Land in Northern Shaanxi,studies the advantages and disadvantages of desert sand mining concrete compared with ordinary concrete,and obtains the favorable performance characteristics of desert sand mining concrete applied in coal mines.The research in this paper can provide technical reserves for the later improvement of "green coal mining" mining methods. |
