Energy Evolution Characteristics Of Roadway Surrounding Rock Reserved Under Filler Layer Support Conditions

In the process of roadway mining,the filling layer is used to absorb part of the surrounding rock energy,and then release the surrounding rock pressure to control the deformation of surrounding rock,which is of great significance to the stability and safety of surrounding rock.Taking Baiyangling Coal Mine Project as the background,this paper studies the influence law of filling layer of fiber foamed concrete on the elastic strain energy of roadway surrounding rock through the combination of laboratory mechanical test,digital speckle test and numerical simulation.The main contents are as follows:（1）The fiber foamed concrete was prepared,and the effects of fiber content,water-binder ratio,fly ash content and foam content on the compressive strength of the sample were studied by response surface methodology.The results show that the interaction of fiber content and fly ash content has the most obvious effect on the compressive strength of the sample,and the optimal ratio of fly ash is 33%,fiber is 0.20%,and foam dosage is 40g.（2）Using the cusp point mutation theory,the elastic strain energy calculation formula was formed into a sequence formula to solve the elastic strain energy mutation discriminant of roadway surrounding rock.（3）Using FLAC^3Dsoftware to simulate the elastic strain energy of roadway with or without filling layer for comparison.The results show that the roof,floor and side can absorb energy more uniformly after adding filling layer,and the overall elastic strain energy of surrounding rock with filling layer is less than that without filling layer,and the filling layer with foamed concrete plays an effective role in energy absorption.（4）Study the influence of width to height ratio,buried depth and lateral pressure coefficient,driving speed and other factors on the elastic strain energy of surrounding rock of roadway under the condition of supporting with filling layer,and analyze the stability of surrounding rock of roadway by using the sharp point mutation theory.The results show that in the state of filling layer,when the width to height ratio is greater than 0.5 and less than 1,the surrounding rock of the roadway is in a stable state.When the triaxial stress of the surrounding rock is less than15MPa,the surrounding rock is in a stable state.The change of tunneling speed has no obvious effect on the stability of surrounding rock.