Combined Selection And Application Of Goaf Exploration Method In Coal Mine In Railway Engineering

In recent years, our country has carried out a large-scale railway construction.High-speed railway (or passenger dedicated line) because of its high speed of200-350km/h, strictly for railway curve radius, slope, road, the settlement and deformationrequirements, degree of freedom for the smaller line selection in survey and designprocess, in addition to the necessary City, tunnel, bridge scheme of restrictions, manyline scheme must after the little coal mined-out area and its vicinity. Deformationsmall coalpit goaf and uneven settlement will pose a huge threat and danger to railwayoperation. For smaller around to avoid large-scale coal mined-out area or on the linemust pass through the goaf treatment, in the investigation and design period, shouldidentify the goaf depth and plane distribution, to provide basic data for diseasetreatment line schemes and goaf.Small coal mined-out area because of its distribution difference or partialcollapse, geological survey difficulties. Drilling although intuitive, but "a peepholeview" can not be macroscopic evaluation of goaf. Geophysical exploration method,cost is relatively low, the speed is quick, especially for macroscopic evaluation onengineering geological conditions of empty, has gradually been widely applied.According to the coal mine goaf exploration, at present there are two maindifficulties: one is the small coalpit goaf wet or partial collapse, and the coal bearingstrata (rock) physical difference, namely the mining area and the surrounding rock arelow resistance and low seismic velocity medium; two is the empty hole diameter withthe depth ratio (ratio of diameter to depth) is small, the geophysical prospectingtechnology, surface geophysical methods in general detection accuracy is not high, inthe mined-out area location and buried depth of quantitative interpretation is verydifficult. Therefore, the small coal mine prospecting mined-out area is a big problempuzzled railway geological exploration, technology is a difficult problem of railway engineering geophysical urgent. Through the detection of the nearly ten years of smallcoal mine goaf, selection in geophysical prospecting method and combination mode,select the field work parameters, data interpretation has also made some progress.Currently in the railway survey methods for the mined-out regions includeengineering geological mapping, drilling, geophysical exploration. Engineeringgeological survey work is the basis of mined-out area survey, before the goafreconnaissance and detailed exploration. For an empty area of state-owned largemines, mine geological and mining data is generally more complete, to ascertain thedistribution range of goaf, geophysical and drilling work is often used as auxiliarymeans of authentication; but for small coalpit goaf, information is often incomplete oreven no data, then must take the geophysical prospecting, drilling verification meansto mining distribution on the detection of underground mined-out area. Investigationof coal mine goaf detection mainly uses the combination of drilling and geophysicalexploration, geophysical methods used by the main geological radar, high densityelectrical method, super high density resistivity method, the quadrupole symmetry DCelectrical sounding method, cross hole seismic wave transmission tomography (CT),transient electromagnetic method, seismic reflection wave method, theelectromagnetic wave tomography, magnetotelluric method, gravity method. Eachmethod has its own character, can solve some problems, but there is also scope strictly,do not use a method to resolve all problems in mined-out areas.Usually, in the railway engineering coalpit goaf area exploration, detection of200m below the surface of the coal goaf by natural field audio magnetotelluricmethod, if the terrain is smooth, can also be used in transient electromagnetic method;detection of100m below the surface of the coal goaf with (super) high densityresistivity method; for detailed investigation coal mine goaf, can be matched with thedrilling and exploration, the seismic wave transmission tomography method.This paper based on the geological radar, high density electrical method, super highdensity resistivity method, the quadrupole symmetry DC electrical sounding method,cross hole seismic wave transmission tomography (CT), used alone or integratedcomparison of transient electromagnetic method, method of seismic reflection wave,electromagnetic wave tomography, magnetotelluric method, gravity method suitablefor all kinds of methods, clarifying the scope, as well as the advantages,characteristics and defects, on this basis, the comprehensive analysis, further selectedcombinations for railway coal mining method prospecting effective space or multiplemethods, main technical methods and means of investigation has provided for therailway engineering coal follow-up the mined-out area.