Changes of Precipitation Infiltration Recharge in the Circumstances of Coal Mining Subsidence in the Shen-Dong Coal Field,China

Coal mining subsidence is a universal environmental-geological problem in mining areas. By selecting the Shen-Dong coal mining subsidence area as the research field, this paper studies the changes in precipitation infiltration recharge in the circumstances of coal mining subsidence by means of field geological investigation and laboratory simulation experiments, which is expected to provide a scientific basis for eco-environmental restoration in the mining area. The results indicate that at the unstable stage of subsidence, three types of subsidence in the Shen-Dong mining area have positive effects on the precipitation infiltration recharge, and the type of full-thickness bedrock subsidence has the greatest influence. In the stable stage of subsidence, the precipitation infiltration process after long- term drought and the moisture migration in the aeration zone undergo three different stages： evaporation-infiltration before precipitation, infiltration-upward infiltration-infiltration during precipitation and evaporation-infiltration after precipitation. During a heavy rainfall infiltration process, the wetting front movement in fine sand, coarse sand and dualistic structure of fine-coarse sand consists of two stages： the stage of wetting front movement during precipitation, in which the wetting front movement distance has linear relationship with the depth, and the stage of wetting front movement after precipitation, in which the wetting front movement distance has the power function relationship with the depth. The wetting front movement velocity is influenced by the rainfall amount and the lithology in the aeration zone. However, as the depth increases, the movement velocity will decay exponentially.

Role of the different planting age of seabuckthorn forests to soil amelioration in coal mining subsidence land

To investigate the effects of seabuckthorn(Hippophae rhamnoides)on soil amelioration,using the space replacement method,soil physical and chemical indexes as well as the microorganism quantity and soil enzyme activities were analyzed.The results showed that:the soil bulk density of surface soil decreased and soil porosity and field capacity increased after afforestation with seabuckthorn.The plant was found to effectively reduce the soil pH,increase the soil conductivity,soil organic matters and available nutrients.Soil microorganism quantity,soil enzyme activities were both higher in 0-20 cm layer than in 20-40 cm layer.With the increase years of remediation with seabuckthorn,the quantity of soil microorganism and enzyme activities were increasing to a higher level 5 to 8 years later.Our study indicates that seabuckthorn can effectively improve soil physical and chemical properties,increase the quantity of soil microorganisms and enzyme activities,which is of great significance for the ecosystem restoration in mining areas.

Study on Spatial Variation of Soil Moisture in Coal Mining Subsidence Area in Mu Us Sandy Land

In order to explore the spatial distribution and variation characteristics of soil moisture in coal mining subsidence area in Mu Us sandy Land,and provide theoretical basis for the restoration of the mining area,experiments based on a linear sampling and classic statistical and geostatistical methods were conducted. Spatial distribution characteristics and variation of soil moisture in the typical 0 to 100 cm dune area in the subsidence area and the non-subsidence area( control) were studied. The results showed that in the typical sand dune location of nonsubsidence area( control),the probability distribution curves of soil moisture changes in all layers along vertical and horizontal directions were all normal distribution,and it was consistent with the temporal and spatial variation characteristics of soil moisture in conventional dunes in Mu Us sandy land. By contrast,two years after the coal mine collapsed,the variations of soil moisture in different layers along vertical and horizontal directions were different,and soil moisture loss was more serious than that of control dune by nearly 10% to 30%,and the standard deviation varied from 0. 54 to 1. 05,increasing by 52. 08% compared with the non-subsidence area( control). The probability of positive and negative deviation greater than 1 was over 50%,and the coefficient of variation varied from 0. 14 to 0. 28,which was 80% higher than that of nonsubsidence area( control). After collapsing,the average level of soil moisture,standard deviation,variance and variation coefficient had greatly changed,and influence of coal mining subsidence on soil moisture was the most in the middle layer( 30-70 cm),and was not obvious in the surface( 0-20 cm) and lower layer( 80-100 cm). In coal mining subsidence area,the dispersion degree of soil moisture in different layers along the vertical and horizontal direction was greatly improved,which increased spatial variation of soil moisture.

Safety appraisement on building natural gas pipeline over coal mining subsidence area

The target of the text is to scientifically appraise dynamic development of surface deformation in subsidence area and its influence on groundwork stability of natural pipe and then adopt some technological measures to ensure safe circulation of natural pipeline. Analysed the influence on natural pipeline from coal mining subsidence in the way of pipeline grade variation, vertical curve variation, transverse deformation, horizontal pull and compression deformation and pipe stress variation etc., and described detailed surface subsidence product and its used time among initial phase, active phase and decline phase in the course of surface movement deformation time. In the context of considering surface subsidence that doesn＇t reach basic latter end and residual subsidence quantity, the text confirmed the calculation method of residual deformation in surface subsidence area, and gave the technological measures about building natural gas pipeline in subsidence area finally.

An Evaluation Study on Water Ecological Civilization Construction in Coal Mining Subsidence Area

By combining expert consultation and field investigation,an evaluation system,consisting of 29 indices in 5 aspects of water safety,water ecology,water management,water landscape and water culture,was established for water ecological civilization construction in coal mining subsidence areas.The weight of the indices was determined using improved group-decision fuzzy analytic hierarchy process and fuzzy mathematical method,and their score was determined according to their value before the pilot and the value at the end of the pilot.Combined with the weight,the actual score of the indices was obtained.Finally,a comprehensive index of water ecological civilization in coal mining subsidence areas was obtained.Through the weight and score of the indices,the construction status,existing problems and future tasks of coal mining subsidence areas were analyzed,in order to provide a reference for the region to further clarify the direction and key tasks of water ecological civilization construction.

Impact of Coal Mining Subsidence on Sandy Geomorphology and Vegetation Habitat in Sandy Area

[Objectives]To explore the problem of"secondary desertification"caused by coal mining subsidence in sandy area and its control countermeasures.[Methods]The collapse fissure changes,vegetation displacement and tilt,dry sand layer and wind erosion/aeolian deposit rate of the edge,middle and basin of subsidence area were studied in detail.[Results]The width and density of fissures at the edge of subsidence area were the smallest,followed by those in the center,and the width and density of fissures in the basin of the subsidence area were the greatest,while the staggering and surface damage showed the opposite trend.The average displacement length of vegetation in the subsidence area reached 60 cm,the slope was 5.67-28.63,and the maximum wind erosion/aeolian deposit at the trunk roots was-30.52 cm/+25.41 cm,most serious at the edge of subsidence.The changes in displacement length and slope of vegetation were positively linearly correlated with the height and surface damage of collapse fissures.The thickness of dry land layer at the edge of the subsidence area reached 14 cm,4-6 cm greater than that of the control,and the thickness of dry land layer in the middle and basin of the subsidence area was both about 11 cm,1-4 cm greater than that of non-subsidence area.The wind erosion rate at the edge of the subsidence area was up to 83.34%,followed by that(52.06%)in the middle.The aeolian deposit rate in the subsidence basin was 51.84%.[Conclusions]The subsidence edge has the strongest impact on the sandy geomorphology and vegetation habitat,and is a key area for ecological restoration.It is recommended that the coal mining subsidence should be treated in a timely manner to avoid the occurrence of"secondary desertification".

Quantitative evaluation of soil erosion of land subsided by coal mining using RUSLE

Based on a RUSLE model, we identified the key factors of the impact on soil erosion induced by coal min- ing subsidence. We designed a method for predicting/.S factors of a mining subsidence basin, using ana- lytical GIS spatial technology. Using the Huainan mining area as an example, we calculated the modulus of erosion, its volume and classified the grade of soil erosion for both the original area and the subsidence basin. The results show that the maximum modulus of erosion and the volume of erosion of the subsi- dence basin without water logging would increase by 78% and 23% respectively compared with the ori- ginal situation. The edge of the subsidence basin, where the land subsidence was uneven, is subject to the greatest acceleration in soil erosion. In the situation of water logging after subsidence, the maximum modulus of erosion would decrease if the accumulated slope length were reduced. This maximum mod- ulus around the water logged area within the subsidence basin is equal to that without water logging, while the total volume of erosion decreases. Therefore, mining subsidence aggravates soil erosion espe- cially at the edge of basins where water and soil conservation measures should be taken.

Assessment of pot-hole subsidence risk for Indian coal mines

Ground subsidence induced by extraction of coal seam belowground brings about changes in surface environment leading to trough and pot-hole subsidence.Pot-hole subsidence is extremely hazardous and does not give any prior indication before its occurrence.In India,several pot-holes have occurred in the coal mines of South Eastern Coalfields Limited triggering the need for in-depth studies.In line with the requirement,literature review and field investigations were conducted to develop an in-depth understanding of various parameters influencing the occurrence of pot-holes.The critical parameters identified were rock to soil ratio,depth to height of extraction ratio,brittleness index of rock and rock density.Risk assessment of pot-hole subsidence has been done by developing an empirical rating approach named as pot-hole subsidence rating(PHSR),involving the critical parameters with suitable corrections for certain structural and mining conditions to obtain corrected PHSR(CPHSR).CPHSR was then applied for all the 34pot-holes studied and it was found that all the pot-holes fall under Class I and Class II category of risk representing a very high to high risk class.An effort was made for the estimation of pot-hole depth utilizing the developed CPHSR in both the development and depillaring cases.The developed approach was found to yield consistent results in pot-hole depth prediction.

Effects of Coal Mining Subsided Water Area on Temperature Change in Huaibei Coal Mine

[Objective] The study aimed to discuss the effects of coal mining subsided water area on temperature change in Huaibei coal mine. [Method] Based on the data of monthly temperature from 1957 to 2007 recorded by Suixi （coal mining subsided water area） and Fuyang stations （control）, the effects of coal mining subsided water area on temperature change in Huaibei coal mine were discussed using linear trend estimation and comparative analysis methods. [Result] Spring, autumn, winter and annual average temperatures of coal mining subsided water area （Suixi） were increased in the last 51 years, and the increase of winter temperature was mostly significant with a tendency rate of 0.49 ℃/10 a. Meanwhile, annual temperature range of coal mining subsided water area was decreased from 1957 to 2007. Temperatures of Suixi in four seasons were lower than those of Fuyang from the 1960s to 1990s, and temperatures of coal mining subsided water area （Suixi） were higher than those of Fuyang in spring, autumn and winter but lower than those of Fuyang in summer from 2000 to 2007. [ Result] Coal mining subsided water area had certain effects on temperature change of Huaibei coal mine.

Agricultural impacts of longwall mine subsidence:the experience in Illinois,USA and Queensland,Australia

Unlike conventional room and pillar underground coal mining,where subsidence is designed to be prevented,subsidence is a planned outcome of other methodologies.These include high extraction retreat,where the roof supporting pillars are systematically removed,and longwall mining,which employs a machine that mines a continuous strip of coal,thus leaving no roof supports.Both types result in the surface dropping -70% of the mined-out thickness.In Illinois there was a concern that farm land thus subsided would be lost to productive agriculture.Consequently,the possibility that planned mine subsidence would be banned in Illinois lead to the creation of the Illinois Mine Subsidence Research Program in 1985 to investigate agricultural impacts of planned mine subsidence and the possibility of mitigating its impact.Its findings established that subsidence was not as detrimental as feared and that the impacts could be mitigated.The project was a successful collaboration of state and federal governments and local Universities.Similarly,in Queensland,longwall mining is opposed by some in the farming community.In response,Bandanna Energy,the company planning the mining,organized the Agricultural Coexistence Research Committee to oversee research into the mitigation of longwall mining impacts.Although the soils,climate,and regulatory regimes are different,concerns of the local communities are similar.

Evaluation of Mine Geological Environment of Guqiao Coalmine

The geological environment is important for the development of coal enterprises. In the Guqiao coalmine, the information of coal mining subsidence, terrain landform, coal gangue utilization, mine water treatment and several on-site investigations have been analyzed. It holds that its geological environment can be evaluated from three aspects, i.e., geological disasters, terrain and landform destruction, and influence on water and soil environment. The results show that mining activities have serious impacts on geological disasters and terrain landform, while lighter impacts on the water and soil environment. According to the research results, a set of corresponding governance strategies are given. The findings can provide theoretical support for the geological environmental protection and restoration of the Guqiao coalmine.

The Architecture Design Based on the Landscape Conditions: Taking the Architectural Design of Subsidence Area for Example

The relationship between architecture and people, architecture and city, architecture and nature has always been the soul of architectural design. In the architectural design, study on the relationship between architecture and nature needs "site analysis"(mapping), and "natural environment" tends to affect the design results[1]. In many special areas, the design needs analysis of geology, geomorphology, hydrology, vegetation and other landscape elements. Coal mining subsidence area is the product of the conf licts between human activities and natural environment in the process of industrialization. As the research object, coal mining subsidence area can be a good study object to demonstrate architectural design strategies and methods based on landscape, and fi eld defects of the site may be the origin of architectural space organization: architectural concept, structure, morphology, spatial organization are all from the landscape elements.