| Deep mining in underground engineering is normalized,and mine thermal environment caused by high ground temperature restricts further exploration.The Zhujidong Coal Mine is typical thermal mine in Huainan Mining Area,which has been taken as the engineering background.The distribution characteristics and influence factors of the Researching Mine Area geothermal temperature has been investigated.The idea of active heat insulation cooling has been proposed.Inspired by the ground insulation materials,the lightweight aggregate concrete was used to construct the active thermal insulation spray layer,and the various basic performances of concrete were explored.A new thermal insulation concrete material was developed for underground injection.The finite element numerical simulation method was used to discuss the temperature distribution regularity of the surrounding rock in active insulated roadway.The conceive of insulation three-dimensional reinforced concrete lining for mine was put forward.Based on the deep high temperature roadway in Zhujidong Mine,the engineering application and effects evaluation were completed.The main contents and conclusions are as follows:(1)The borehole temperature data of Zhujidong Mine were systematically analyzed.The results show that the ground temperature increases linearly with depth,the geothermal gradient is between 1.7 and 3.6?/hm,mean value is 2.60?/hm,and mean depth of the primary heat damage zone of 31? is-552.01 m,the secondary heat damage zone of 37? is-741.01 m.Most of today main working levels of-906 m and-965 m have reached the primary heat damage zone and some are in the secondary heat damage zone.The vast majority of further work which developed-1070 m and-1200 m levels will reach the secondary heat damage zone.(2)The roadway surrounding rock temperature control was taken as the study object,the heat conduction model of the roadway surrounding rock was analyzed.The heat transfer coefficient is changed by establishing the active thermal insulation layer to block the heat release of the surrounding rock.The lightweight aggregate concrete was proposed to construct the spray layer.It is theoretically confirmed that the lightweight aggregate incorporated into concrete can improve the capacity of thermal insulation from the concrete heat conduction model.(3)The shale ceramsite and glazed hollow bead were used as coarse and fine lightweight aggregate,the workability,high temperature deterioration,carbonation resistance and micro-structures of ceramsite All-lightweight Aggregate Concrete(ALWC)and Sub-lightweight Aggregate Concrete(SLWC),Glazed Hollow Bead Concrete(GHBC)were discussed,and compared with Normal Concrete(NC).The results show that the ALWC and SLWC have greater advantages of strength loss after exposure to high temperature and carbonation resistance than NC.The reason is that ceramsite lightweight aggregate is an excellent heat-resistant material,and the internal suction and return water effect causes the cement stone becoming denser.The strength loss of GHBC after exposure to high temperature is similar to that of NC,and the carbonation resistance is inferior to that of NC,but the incorporation of glazed hollow bead is beneficial to fluidity of mixture.The interfacial embedded transition zone was formed with lightweight aggregate and cement matrix in microscopic view,and the destruction is often caused by the low strength of lightweight aggregate,which overcomes the weak disadvantage of NC interface zone.(4)For thermal insulation concrete spray layer,the ceramsite insulated concrete and ceramsite glazed hollow bead insulated concrete were developed by orthogonal experiment.For ceramsite concrete,the effects of different grades ceramsite,different content of ceramsite,fly ash and sand on material performances were discussed.For ceramsite glazed hollow bead concrete,the effects of different content of ceramsite,glazed hollow bead,fly ash and sand on material performances were discussed.The performance test included apparent density,thermal conductivity,compressive,tensile and flexural strength.The influence order of each factor on various performance was obtained by range analysis.The influencing weight of each factor was obtained by analytic hierarchy process.The optimal ratio of comprehensive performance was obtained by efficiency coefficient method.(5)The ANSYS finite element software was used to analyze the temperature distribution regularity of surrounding rock in active insulated roadway.The influence of thermal conductivity,thickness of insulated concrete spray,thermal conductivity,temperature of surrounding rock on the roadway temperature field was discussed.The results show that the thermal properties of the surrounding rock determine the roadway surrounding rock temperature distribution,and rock temperature is the most sensitive factor.It can prevent heat transmission and reduce the influence of wind flow on the surrounding rock temperature field by suing low thermal conductivity spray layer and increasing thickness of layer,but weakened with time.The sensitivity of spray layer thermal conductivity is higher than layer thickness.Therefore,the use of low thermal conductivity spray layer has positive significance for the thermal environment control of deep mine.(6)A new functional support structure and method of active insulated deep rock temperature was proposed by combining with half-rigidity shell bolting shotcrete support structure and thermal insulation concrete spray layer,the insulation three-dimensional reinforced concrete lining for mine.The strong support ability of shell structure ensures roadway long-term stability.The active heat insulation effect of thermal insulation concrete is used to block heat transfer from surrounding rock to roadway,which playing the role of active thermal insulation and cooling.Based on the 8 coal roof return airway of east in Zhujidong Mine,the industrial application of thermal spray layer about 100 m was carried out.The results show that the high temperature heat damage is serious,the temperature of driving working face maintains above 27? for long-term,the wall temperature exceeds 27.5?,and the relative humidity maintains above 70%.The wall temperature has decreased after using the insulated concrete spray layer.The field sampling test results show that the thermal conductivity of insulation spray layer reduced significantly.This technology is a benign measure for energy conservation and emission reduction,providing new ideas for mine thermal environment control.Figure[117]table[56]reference[239]... |
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