Research On The Influence Of Complex Environment On The Performance Of Super-high Water Packing Materials

The super-high water packing material has the advantages of simple filling process,less filling material consumption,fast material solidification,etc.It has good application prospects in filling the goafs,especially in mines which lack sources of packing materials in the surrounding area.However,in the process of filling and mining,the super-high water material is relatively sensitive to external factors such as construction conditions and the environment of the goaf due to the high water cement ratio,which cause its properties such as setting time,compressive strength and long-term stability easily affected.Based on the actual engineering conditions,this paper studies the performance changes of super-high water materials affected by factors such as different construction water temperature and PH,environmental temperature,weathering,and acid-base environmental erosion,providing guidance for engineering practice and optimizing field filling effects.By combined the above site engineering affecting factors,the super-high water material samples were preparated and cured.And integrated macroscopic and microcosmic test methods such as compressive strength test,SEM scanning electron microscopy,X-ray diffraction analysis and DTA-TG thermal analysis,a series of laboratory tests were carried out to reveal the mechanism of different factors affecting the performance of super-high water materials.At the same time,a creep test device was designed to simulate the different surrounding rock permeable environment in the goaf,and the creep test of super-high water materials under long term loading was carried out to explore the long-term stability of super-high water materials.The main research conclusions are as follows:(1)The economic temperature of the construction water of super-high water materials should be controlled at 20 ℃-30 ℃,and the acidity and alkalinity should be controlled at PH = 4-13.Excessively high or low temperature of construction water will affect the internal hydration process of the material and weaken the strength of the material.Excessive acidity and alkalinity of the construction water will destroy the ion balance of the material and inhibit the morphology and generation of calcium vanadium,that affect the material strength.(2)The super-high water material is suitable for filling in goaf with temperature of 0 ℃-40 ℃,no acid mine occurrence and good airtightness.Excessively high temperature in goaf will weaken the growth of late strength of materials;the existence of acid mine water will continuously erode the super-high water material filling body,destroy the internal ettringite structure and generate large amounts of gypsum,which seriously weaken the bearing capacity of the filling body.Under the air leakage conditions in the goaf,the free water of the filling body will be lost,and the eeeringite will be carbonized and decomposed,the filling body will lose its strength finally.(3)The super-high water material is suitable for filling in goafs with poor permeability of surrounding rocks.In fully enclosed goaf environment,the super-high water material is incompressible.With the increase of the permeability of surrounding rocks,free water loss amount increases,the filling body’s ability to resist deformation becomes weaker.Finally,the water pressure in the goaf and the filling body form a solid-liquid stress equilibrium state,which together constitute the bearing structure of the super-high water material.