| As coal mining enters the deep stage,deep roadways are under the coupling of multiple fields like temperature field,humidity field and stress field.Based on this,this paper establishes a calculation model for the stress field of the surrounding rock of the roadway under the coupling of multiple fields firstly,discusses the influence of high temperature and high humidity stress on the stability of the surrounding rock,and proposes solutions.Secondly,it combines the cooling idea of active insulation and the green mine's concept.To design orthogonal experiments,and develop a new type of heat insulation shotcrete that can reduce the impact of high temperature and high humidity stress on the stability of surrounding rocks.Then,based on the engineering environment,to carry out a temperature and humidity cycle treatment of the heat insulation shotcrete and study them separately.Searching for the characteristics of creep test and impact mechanical while after the action of temperature and humidity cycles.Finally,relying on the belt conveyor lane of the west 3rd concentration belt of Dingji Mine of Huainan Mining Group as the engineering background,the field application and effect evaluation of this new type of heat insulation shotcrete.The main research conclusions are as follows:(1)Under the coupling of multiple fields,temperature and humidity stresses will occur when the temperature and humidity fields change,and the effects of temperature and humidity stress will cause additional stress in the roadway.When the floor of the roadway is not supported or lacks support,the additional stress caused by temperature stress and humidity stress will significantly change the stress field and displacement field in the surrounding rock of the roadway,and affect the stability of the surrounding rock of the roadway.Therefore,the following measures need to be taken:establishment of a floor support mechanism or roadway insulation treatment.(2)A new heat insulation shotcrete composed of ceramsite,pottery sand,basalt fiber and plant fiber.The orthogonal test results show that the best amount of each factor is ceramsite to replace 7%quality stone,pottery sand to replace 8%quality sand,basalt fiber content to 0.2%volume concrete,and plant fiber content to 0.2%volume concrete.At the same time,the micro-test results show that when ceramsite.pottery sand,basalt fiber and plant fiber are mixed in the concrete,the hydration reaction of the cement slurry in the concrete is not affected by the above admixtures,and the strength is well developed,and there are no harmful substances and adverse reactions appear.(3)The creep test results of heat insulation shotcrete show that under the four water bath temperatures(24?,40?,60?,and 80?),the axial creep strain of heat insulation shotcrete increases with the number of wet and dry cycles.Both of them reached the maximum value after 3 cycles of wet and dry cycles.Then after the same 3 cycles of wet and dry cycles,the axial creep strain of the test piece was the largest at 60? water bath temperature,and the test piece was at 80? water bath temperature.The axial creep strain is the smallest;in addition,when the temperature of the water bath is between 24? and 40?,its average instantaneous deformation modulus is the largest when the wet and dry cycle is applied 14 times,at which time the degree of degradation is the lowest when the temperature of the water bath is 60? to 80?.Its average instantaneous deformation modulus is the largest when the wet and dry cycle is applied 7 times,and its degradation degree is the lowest at this time.Therefore,at low water bath temperature,the heat insulation shotcrete is eroded slowly,and at high water bath temperature,the heat insulation shotcrete is eroded fastly.Finally,the creep test results of the heat insulation shotcrete conform to the Burgers model,and there are formulas between the four calculation parameters E1,E2,?1,and ?2 and the temperature T and the number of wet and dry cycles n like(4-5)-(4-8),which being substituted into equation(4-3)is the Burgers constitutive model heat insulation shotcrete at temperature T and wet cycles n effect.(4)The impact test results of heat insulation shotcrete show that under the impact load,the dynamic compressive stress-strain curve of heat insulation shotcrete can be divided into three segments:the elastic phase,the yield phase,and the failure phase.Among them,the yield phase has obvious yield.The platform indicates that the impact resistance of heat insulation shotcrete is better.At a water temperature of 24? to 40 0C,the dynamic compressive strength of the heat insulation shotcrete decreases first with the increase of the number of dry and wet cycles,and at 14 dry,it reached the minimum under the action of wet cycle,and then reached 28 dry and wet cycles,the dynamic compressive strength of the concrete rebounded.Under the water temperature 60? to 80?,with the increase of the number of dry and wet cycles,the dynamic compressive strength of heat insulation shotcrete decreases firstly and then increases,reaching its maximum under 14 wet and dry cycles.After that,as the number of dry and wet cycles increases,the dynamic compressive strength of concrete begins to decrease again.When the temperature is constant,the dynamic compressive strength conforms to the following rules as the water temperature increases.When the temperature and humidity cycle is 3 to 7 times,the insulation spray mixes the dynamic compressive strength of the soil continues to decrease.The dynamic compressive strength of heat insulation shotcrete decreases first as the water temperature increases 14 to 28 cycles of temperature and humidity.At 60?,the dynamic compressive strength of heat insulation shotcrete decreases.Finally,as the water temperature reached 80?,the dynamic compressive strength of heat insulation shotcrete began to decrease again.There was a formula(5-5)-(5-9)(5)The engineering application of heat insulation shotcrete in the roadway of west 3rd concentrated belt conveyor,Dingji Mine,Huainan Mining Group shows like that.Under the three forms of support(full section heat insulation support,composite support,full section without heat insulation support),the wall temperature of the concrete decreases effectively,only 27.1?,which is lower than the average air temperature of 28.7? in the whole roadway,and the temperature difference is about 7? from 0.5m in the surrounding rock while with the support form of full section heat insulation.To compared with the full section without heat insulation support,the radius of the rock heating circle is only 4.44m in the section of full heat insulation,which is significantly lower than the 7.0m of the ordinary section.In addition,by comparing and analyzing the monitoring results of the surrounding rock convergence and the pressure of the concrete spraying layer,the results show that the surrounding rock of the heat insulation support section has converged volume and spray pressure are small.In consideration of economy,the support form of composite lining layer is recommended.Figure[83]table[44]reference[174]... |
PDF Full Text Request