Study On Distribution Characteristics, Genetic Mechanism And Activity Prediction Model Of Ground Fissures In Fushun City

Fushun City,Liaoning Province,is a major large-scale resource-based mining city of China.Due to the complex geological structure background and human engineering activities such as Hunhe activity fracture,underground mining and open coal mining in Fushun city,the ground fissures of different causes are widely distributed in the urban area,which seriously affect the economic development and social stability of Fushun City.Based on comprehensive investigation and research on the ground fissures in Fushun city,this paper aims to find out the distribution characteristics and genetic mechanism of ground fissures in Fushun city and construct a set of research methods for ground and rock fractures and geological disasters of mining cities and establish the prediction model of ground fissures in the Fushun City.This study also aims to provide a basis for urban planning,sustainable development and environmental management of Fushun City and also provides reference for the prevention and control of geological disasters in other resource-based cities.It is of great theoretical and practical significance for the study of mine-type ground fissures.First of all,this paper begins with the geological background of Fushun Ground fissures,establishes the geological structure model of fractures in each region,masters the crack-gestated environment of the fissures and find out the distribution regularity,development status and the relationship with the underlying tectonic fracture in Fushun city.Secondly,based on the characteristics of ground subsidence and deformation,this study explores the relationship between ground subsidence deformation and ground fissure combined with the distribution characteristics of ground fissures in study area then carries out researches on mining subsidence deformation prediction model to realize the monitoring and prediction of ground fissure activity trend.It can draw the following conclusions from this research:1)Ground fissures in Fushun city are typical mine-type ground fissures,a total of 12 ground fissures at present.The ground fissures are the tectonic fracture surface connected with the underlying faults.The overall trend of ground fissures is NEE,which has obvious characteristics of general consistency and is consistent with the main faults in Fushun city.According to the regional distribution and the characteristics of the geological background,it can be divided into four main fracture zones: ground fissure zone in the south slope of Fushun West Open-Pit Mine,including I and II ground fissure,whose geological structure model is a canyon type controlled by the granite gneiss ancient weathering crust and basalt weak fragmentation;Nanyang Road ground fissure zones in the north slope of West Fushun Open-Pit Mine,including III,IV and V ground fissure,whose geological structure model is deeply inserted-canyon type controlled by the Hunhe series fault zone;Labor Park-Haixin River ground fissure zones,including VI,VII,VIII,IX,X and XI ground fissure,whose geological structure model is deeply inserted type controlled by the Hunhe series fault zone;Haixin Road ground fissure,including XII ground fissure,whose geological structure model is basin type controlled by F13 fault.Ground fissure zone in the south slope of West Fushun Open-Pit Mine is the most active zone among above ground fissure zones.2)The deformation characteristics of ground subsidence caused by underground mining are in accordance with the characteristics of "S" type curve.The predictive and forecasting model of ground subsidence deformation is a real-time model based on arctangent function.It can get the latest fitting parameters from the latest monitoring data and generate the latest fitting curve through the constant correction of parameters.The model can grasp the dynamic development trend of deformation in time and exhibit good application effects in short-term prediction and forecast.Thus it can be applied to forecast the development trend of ground fissure induced by underground coal mining due to its high prediction accuracy.3)XI-VI ground fissures are located in the influencing region of Laohutai mine collapse pit and its north side.The farther away from the mining center,the smaller of the deformation of the vertical settlement of the ground,the more loose of the settlement deformation contours and the development scale and intensity of the fractures in the vertical direction get smaller and smaller.In the direction of NE extension of the Hunhe tectonic fault zone,the ground fissures stops developing when the influencing range of underground mining and the barrier effect of F13 fault are exceeded.4)Ground fissure zones in the south slope of West Fushun Open-Pit Mine belong to trailing edge ground fissure of the super-large-scale and double-sliding landslide,which is a non-tectonic fissure of human opencast coal mining as the dominant factor.Underground coal mining,open coal mining,tectonic fracture and horizontal tectonic stress are the main factors affecting the formation and development of the remaining fractures.Hunhe fault zones are under the impact of the collision between the Pacific plate and the Indian plate,which leads to the hidden cracks directly to the surface because of the long-term peristalsis of the fault of deep crust.The Hunhe series fault zone is dislocated under the action of the underground coal mining and open coal mining,which caused mutational deformation in the surface then causing excessive ground fissures.Therefore,most of the fractures in Fushun city are the mining sinking-structure fissures with crack-gestated environment of the fault structure and crack-opened condition of the underground coal mine and the open coal mine mining and limited by high horizontal tectonic stress.With the continuous excavation of underground coal mines and open pit coal mines,the intensity of activity of ground fissures increases in various regions.5)The effect of horizontal tectonic ground stress on the formation and development of ground fissures is considered for the first time.The numerical simulation results are: horizontal tectonic in situ stress can curb ground fissure activity to a certain extent,but it will increase the intensity of the crack in the reverse direction after exceeding the limit.The intensity of response to horizontal tectonic stress is different in different regions.The influence of the horizontal tectonic stress on the development trend of the ground fissure is more intense due to the existence of the open pit,and the stress limit is 25 MPa.And with the increase of horizontal tectonic stress,the reverse intensity of ground fissure in this area becomes higher.While the other sections,the stress limit develops to 60 MPa or even larger.6)Analyze the influence of underground coal seam thickness,burial depth and horizontal excavation distance on typical crack activity(including vertical and horizontal direction)by numerical simulation.The results show that in the case of keeping any other two conditions unchanged: coal seam thickness increases,and ground fissure activity increases;the burial depth of coal seam increases,and the activity of ground fissure is weakened;The level of excavation distance increases,and ground fissure activity increases.And the human mining activity represented by the horizontal excavation distance has the greatest influence on the activity of ground fissures.The ternary n-degree polynomial function prediction model,which is based on the relationship between the thickness of underground coal seam,burial depth,horizontal excavation distance and typical crack activity curve,has high matching accuracy with the numerical data.The prediction of the vertical and horizontal movement of ground fissures can be achieved by the input of three influencing factors.