Study On Performance Of Rubber Concrete Support Structure For Large Chamber Under Complex Geological Conditions

Because of its large cross-section size and high initial in-situ stress in the rock stratum,the deep large-section chamber has serious failure and instability,and it is difficult to control.The rubber concrete with low density,good toughness and strong crack resistance is applied to support large section soft rock chamber,which can reduce the stress concentration of the chamber and ensure the stability of the chamber and supporting structure.Through selecting rubber particles with 20 mesh(0.85 mm),the compressive strength test,splitting tensile strength test and 50 times high stress constant amplitude cyclic loading test were carried out on rubber concrete specimens with 0%,5%,10%,15%,20%rubber content.By using the numerical simulation software,three different situations of large diameter coal bunker excavation without support,coal bunker excavation with ordinary concrete support and coal bunker excavation with rubber concrete support are carried out.The conclusions are as follows:(1)The compressive strength and splitting tensile strength of concrete are reduced by adding rubber particles into the concrete,and the decreasing trend of the compressive strength and splitting tensile strength is more obvious with the increase of the replacement rate of rubber particles.When the rubber content is less than 10%,the strength of the specimen decreases slowly.When the rubber content exceeds 10%,the strength of the specimen decreases more obviously.(2)When the rubber particles are added into the concrete,the tensile compression ratio of the rubber concrete increases with the increase of the content,which indicates that the brittleness decreases and the toughness increases.(3)The strength test of rubber concrete with different amount of rubber under cyclic loading is carried out.The mechanical properties of each group of concrete are comprehensively evaluated by efficacy coefficient analysis.The order of comprehensive evaluation is rubber content 5%>10%>20%>15%>0%.Therefore,it can be determined that 5%～10%is the best rubber content of rubber concrete.(4)Using FLAC3D numerical calculation and analysis software,three different situations of coal bunker are calculated.After the coal bunker support,the stress concentration phenomenon is obviously reduced,and the rubber concrete support has a more obvious weakening effect on the concentrated stress,which is 22.64%lower than that of the ordinary concrete support.Compared with ordinary concrete support,the maximum displacement and deformation of coal bunker decreased by 72.70%compared with that without support,and the displacement deformation of rubber concrete support increased by 14.26%compared with ordinary concrete support.This is due to the better toughness and ductility of rubber concrete,the displacement of support structure slightly increases,but it can release the concentrated stress.Compared with the ordinary concrete support,the tensile stress in the surrounding rock of the coal bunker is weakened after the rubber concrete support,which enhances the stability of the structure.Figure[60]table[19]reference[56]...