Research On Grouting And Filling Materials For Mined-out Region Under Geological Deposits Of Weng’an Biota

The deformation of the overburden rock in the mine-out region can lead to ground collapse,ground fissures,landslide,collapse and other geological disasters,which seriously threaten the construction and safety of high-speed railways,highways,and ground buildings.The treatment of mine-out region is usually performed with grouting and filling.The study of grouting and filling materials is a very important content in the technical system of mine-out region management.At present,the grouting materials used in the mine-out region treatment engineering are mainly cement paste,cement mortar,cement-clay slurry,cement-fly ash slurry,cement-waterglass slurry and so on.These materials have various defects such as high precipitation rate,low rate of consolidation or high cost.Therefore,taking into consideration the existing technical conditions,it is of great practical significance to develop a grouting and filling material which is easy to obtain,convenient to construct,and is low in cost.Based on the control project of the mine-out region under the geological deposits of Weng’an Biota,and in view of the deficiency of the application of the grouting and filling material in the mine-out region treatment,a research on the grouting and material in the mine-out region has been systematically studied.by the combination of theoretical analysis,the laboratory test and the numerical simulation.The major research works include:1.Development and performance evaluation of grouting and filling materialsIn order to investigate the influence of the components of the grouting and filling material on the performance and the best matching scheme,the grouting performance test of the high water-cement ratio cement slurry is first performed.It is found that there are many performance defects,such as large rate of precipitation,low rate of consolidation,and long setting time.So,a modification scheme that incorporates a large proportion of external additives is proposed.It is found that under the condition of high water solid ratio,the rate of consolidation of the large amount of fly ash cement composite slurry has a certain increase compared with the ordinary cement slurry.Then,according to the requirement on consolidation of the grouting and filling in Mine-out region,the modification scheme of adding expansive material to improve the rate of consolidation furtherly is put forward.Through a large number of experimental studies,it is found that adding a suitable proportion of NV expansion agent to the slurry can not only improve the rate of consolidation,but also promote the hydration process of filling material and improve the early strength of the consolidation.At the same time,it is found that the expansion performance and strength development of the composite slurry have good coordination after adding the NV expansion agent.Through a lot of experimental research,it is found that adding suitable proportion of admixture DFZ can reduce the dynamic shear force of the whole compound slurry and facilitate the field application.Finally,two optimization schemes of grouting material in mine-out region are obtained by orthogonal test analysis method.The performance of the optimization scheme is evaluated.2.Discussion on the hydration process of grouting and filling material based on microscopic characteristic analysisIn order to study the hydration process of the grouting material,the micro-morphology of the structure of the grouting material was observed by scanning electron microscope(SEM).The parameters such as fractal dimension and proportion of particle distribution are determined by microscopic structure quantitative analysis method.Combined with the hydration mechanism of cement and the hydration mechanism of fly ash,the hydration process of grouting material system is discussed,and its hydration process model is established.3.Numerical simulation of grouting and filling effectIn order to study the grouting effect of the grouting material when it is applied to control of the mined-out region under the geological deposits of Weng’an Biota,the numerical analysis of the surrounding rock deformation was carried out by using FLAC The results show that the deformation of the mine-out region is mainly in the vertical direction.And the deformation of overlying rock is obviously reduced after the grouting and filling material is applied to fill the mine-out region under Weng’an Biota,which satisfies the requirement of the stability of overlying rock body.The research result provides a feasible solution about material for the grouting treatment of the mined-out region under geological deposits of Weng’an Biota.Furthermore,it has a certain guiding significance and reference value for the similar project.