CN101526629A - Geological prediction system for constructing tunnel passing through coal measure strata - Google Patents

Abstract

The invention discloses a geological prediction system for constructing a tunnel passing through coal measure strata. The condition of the tunnel passing through the coal measure strata is specifically analyzed in a way of geological record, geophysical prospecting analysis or advance borehole according to specific condition based on macroscopic analysis which is adopted in sequence; the obtained information is classified so as to predict the geological condition of a main job and the geologic hazard of the coal measure strata; and the correlative information and data are used for completing the construction of the geological prediction system for constructing tunnel passing through coal measure strata. The invention provides a system for perfectly and exactly predicting the geology for constructing the tunnel passing through coal measure strata.

Description

A kind of geological prediction system for constructing tunnel passing through coal measure strata

Technical field

The present invention relates to geological prediction system for constructing tunnel, especially a kind of geological prediction system for constructing tunnel passing through coal measure strata.

Background technology

Along with the high speed development of China's capital construction cause and the process of development of the West Regions, a large amount of Tunnel Engineering start one after another, wherein are no lack of the complicated geological that the passes through coal measure strata tunnel of growing up.Tame Zhu Qing tunnel total length 4990m as Nanning-Kunming's railway wherein reaches 1157m by coal measure strata length; And for example reach tunnel, mountain, line cloud top total length 7858m, concentration reached 98% when gas was the highest.For the constructing tunnel of passing through coal measure strata, carry out not only necessity and urgent of geologic prediction.Simultaneously, a large amount of engineering practice is also for the formation rule of exploring the gas tunnel geologic hazard with how to carry out successful predicting good opportunity and material is provided.

Pass through system Xu Jia river group on the Trias in the purple Ping Pu of the river in Shangdong Province highway tunnel of founding a capital, its lithology is mainly Dark grey, grey black mud stone, siltstone and sandstone, local folder carbonaceous mud stone, unsettled thin seam, seam etc., tunnel location district are positioned at Central-South section of Longmenshan structural belt, Li Bing and His Son Shrine fracture (fracture of Longmenshan front range) with reflect on the fault block that elegant fracture (Longmenshan central breaks) limited, therebetween spread a series ofly move towards the back of the body of east northeast-north north east, to tiltedly and against thrusting splitting; In the district of tunnel location there be fold: F ₁₀, F _10-1, F ₁₁, F ₁₂, F ₁₃, F ₁₄Deng, minor fault, rub wrinkle and joint fissure is grown, rock crushing～broken.Coal seam, district, tunnel location and Gas Distribution possess following characteristics: 1. coal seam and Gas Distribution irregularities; 2. gas is based on crack gas, and there is pressure-bearing gas in the subregion; 3. rock crushing, joint fissure is grown, and gas possesses good migration condition; 4. the coal body structure is chunky shape, flakey, powdery based on granulated coal, rotten rib coal, and intensity is extremely low.

Because architectonic complicacy and polytrope, if can not accurately verify front of tunnel heading geology state, very easily collapse, water burst and gas hazard, will cause great security incident.

Tunnel Engineering is a Geological Engineering, buried depth is big, the characteristics of hole line length and most of tunnels all have, the geologic condition complexity of passing through, the prospecting work in early stage is difficult to find out fully the geological problem of existence, especially for the great gas tunnel of security risk, construction must be carried out construction geology work such as geological analysis and advance geologic prediction.

The Tunnel Engineering advanced prediction was surging forward in recent years, newly researched and developed multiple forecast instrument and equipment, however, because the place that various instrument and equipments all more or less come with some shortcomings in forecast, only the forecasting procedure of voucher one is difficult to guarantee the accuracy of forecast achievement.As can be seen, present domestic geologic prediction work focuses on the development advanced detection technology and carries out forward probe work, pay attention to not enough to the method for geological analysis, the method that to survey of failing and the method for geological analysis are carried out reasonable combination, in addition, analysis and forecast method are single, do not set up the complete technical method system of a cover.

Summary of the invention

The purpose of this invention is to provide a kind of system more perfect and that can forecast constructing tunnel passing through coal measure strata geology more accurately.

Technical scheme of the present invention is as follows:

A kind of geological prediction system for constructing tunnel passing through coal measure strata, adopt following steps:

Step 1, macroanalysis: consult a large amount of prospecting data, design drawing, geological condition to the engineering district is more comprehensively understood, by analysis to the data in early stage, and in conjunction with the distribution of holding coal measure strata is generally summed up in the forecast and the actual contrast of excavation of the section of digging a hole;

Step 2 is made a concrete analysis of the tunnel passing through coal measure strata situation by employing geological record, physical prospecting analysis or advance borehole means on the basis of macroanalysis as the case may be;

Described geological record is in the tunnel or during wide open digging, stratum, lithology, tectonic structure, underground water and other unfavorable geology phenomenon that discloses is reflected in strictly according to the facts that barrel is showed or truncation figure on, and contrast with the tunnel longitudinal diagram;

Described physical prospecting analysis is to adopt TSP and HSP advanced prediction method to verify mutually, tentatively judges the intact condition than big abnormal conditions and rock mass that may exist in front of tunnel heading 0～150m scope;

Described advance borehole is to find out parameters such as bearing, inclination angle, thickness by the advance borehole test in the excavation when near the coal seam.

Step 3, the information classification that step 1 and step 2 are obtained is also carried out prediction of major project geologic condition and passing through coal measure strata geological hazards prediction;

Described major project geologic condition prediction comprises: lithology and the prediction of country rock integrality, tomography prediction, coal seam prediction, underground water condition predicting;

Described passing through coal measure strata geological hazards prediction comprises: landslide prediction, gas outbursts Prediction.

Step 4, integrating step 1,2,3 relevant informations of being obtained and data are finished the structure of geological prediction system for constructing tunnel passing through coal measure strata.

Press the different of engineering project geologic feature and main geological problem, establishment log sheet, coal seam distribution plan, excavation comparison diagram, progressively main geology key element of geological record and physical prospecting achievement are reflected on the correlogram in the lump with engineering progress during establishment, and repair the volume engineering geological profile according to the geological condition that excavation discloses.

Drilling depth is controlled at 30～50m in described advance borehole, and boring arranges that poorly output scale, the spread form of plastid are determined according to aforementioned forecast.

The core that drills through in the described advance borehole is write and is left in the special core case by professional geological personnel.

The content that described macroanalysis comprises is: regional stability, tectonic structure, formation lithology, topography and geomorphology, texture of coal seam.

The content that described geological record comprises is: face mapping, barrel mapping and geologic examination.

Beneficial effect: the present invention is that prerequisite is by various means with the macroanalysis, situations such as lithology and country rock integrality, tomography, coal seam, underground water situation, landslide, gas is outstanding are carried out omnibearing analysis and prediction, set up cover system perfect and that can forecast constructing tunnel passing through coal measure strata geology more accurately.

Description of drawings

The present invention will illustrate by example and with reference to the mode of accompanying drawing, wherein:

Fig. 1 process flow diagram of the present invention;

The arrangenent diagram of big gun hole and receiver hole in Fig. 2 TSP recording geometry;

Fig. 3 TSP detection principle figure;

Embodiment

As shown in Figure 1: a kind of geological prediction system for constructing tunnel passing through coal measure strata, adopt following steps:

Step 1, macroanalysis: consult a large amount of prospecting data, design drawing, geological condition to the engineering district is more comprehensively understood, by analysis to the data in early stage, and in conjunction with the distribution of holding coal measure strata is generally summed up in the forecast and the actual contrast of excavation of the section of digging a hole;

Step 2 is made a concrete analysis of the tunnel passing through coal measure strata situation by employing geological record, physical prospecting analysis or advance borehole means on the basis of macroanalysis as the case may be;

Described geological record is in the tunnel or during wide open digging, stratum, lithology, tectonic structure, underground water and other unfavorable geology phenomenon that discloses is reflected in strictly according to the facts that barrel is showed or truncation figure on, and contrast with the tunnel longitudinal diagram;

Described physical prospecting analysis is to adopt TSP and HSP advanced prediction method to verify mutually, tentatively judges the intact condition than big abnormal conditions and rock mass that may exist in front of tunnel heading 0～150m scope;

Described advance borehole is to find out parameters such as bearing, inclination angle, thickness by the advance borehole test in the excavation when near the coal seam.

Step 3, the information classification that step 1 and step 2 are obtained is also carried out prediction of major project geologic condition and passing through coal measure strata geological hazards prediction;

Described major project geologic condition prediction comprises: lithology and the prediction of country rock integrality, tomography prediction, coal seam prediction, underground water condition predicting;

Described passing through coal measure strata geological hazards prediction comprises: landslide prediction, gas outbursts Prediction.

Step 4, integrating step 1,2,3 relevant informations of being obtained and data are finished the structure of geological prediction system for constructing tunnel passing through coal measure strata.

Press the different of engineering project geologic feature and main geological problem, establishment log sheet, coal seam distribution plan, excavation comparison diagram, progressively main geology key element of geological record and physical prospecting achievement are reflected on the correlogram in the lump with engineering progress during establishment, and repair the volume engineering geological profile according to the geological condition that excavation discloses.

Drilling depth is controlled at 30～50m in described advance borehole, and boring arranges that poorly output scale, the spread form of plastid are determined according to aforementioned forecast.

The core that drills through in the described advance borehole is write and is left in the special core case by professional geological personnel.

The content that described macroanalysis comprises is: regional stability, tectonic structure, formation lithology, topography and geomorphology, texture of coal seam.

The content that described geological record comprises is: face mapping, barrel mapping and geologic examination.

Specific practice is as follows in each step:

One, geologic condition macroanalysis

The geological syntheses analysis is according to the basic geologic condition of geological theory to tunnel (hole) engineering, many geological problems that in digging process, will face, as gas, tectonic structure, underground water etc., reach any explanation and application, all be unable to do without geological syntheses and judge that it takes place, the inevitable outcome of development physical prospecting, bore detecting data.

The geological syntheses analysis is used the geological origin cause of formation to develop and is discussed, adopt rational approach and advanced Detection Techniques means comprehensively to determine poorly the evaluation of making prediction of character, position and the harmfulness of plastid, be that ground (matter), thing (spy), brill (spy) three are bound organically in one, be that a comprehensive geology achievement is used for instructing production, and be a successional research work.

Geological syntheses analysis means method is a lot, and certain effect is also all arranged.Also each is different to some extent for different according to engineering properties, basic geologic condition and geologic media, the application of its means and method, therefore should be according to engineering actual conditions rational Application when selection approach, method.

Before carrying out geological work, should carry out macroanalysis to engineering geological condition earlier, survey data the Collection and analysis research engineering, and be familiar with understanding on the basis of prospective design data, the possibility that the main geological problem of earnest analytical study engineering exists, and whether these problems are consistent with engineering district geologic background, search the doubtful point and the difficult point that exist in the engineering investigation design.Holding tunnel location regional tectonics, formation lithology, topography and geomorphology and texture of coal seam from macroscopic view distributes.

1. geological record and face sketch

The geological record method is when excavate in (hole) in the tunnel, stratum, lithology, tectonic structure, underground water and other unfavorable geology phenomenon that discloses is reflected in barrel strictly according to the facts shows on (truncation) figure, and contrast with the tunnel longitudinal diagram.Structural plane occurrence, coal seam, underground water and physical prospecting achievements etc. such as emphasis reflection formation lithology, geological boundary, tomography, joint fissure among the figure.Continuous establishment by exploded view can be grasped the poorly variation tendency of plastid in conjunction with Information integration analyses such as physical prospecting achievement and hole line sections, and which kind of formation lithology or adverse geological condition may appear in the prediction front of tunnel heading.

Geological record had both reflected the geology variation characteristic of excavation section, was indicating the not geological problem of excavation section certain limit again.No matter because the generation of which kind of unfavorable geology disaster and development, always it has its special omen feature.Grasped these Changing Patterns and geologic feature by geological record, then be the geological syntheses analysis and to the preciousness of physical prospecting data interpretation according to also being to write engineering foundation data evidence simultaneously.

2. collect all kinds of physical prospecting achievement datas

All kinds of forecast achievements of timely collection also come together on the comprehensive map, as the basis of geological syntheses analysis.

3. work out various maps

Press the different of engineering project geologic feature and main geological problem,, show (truncation) figure, coal seam distribution plan, excavation comparison diagram etc. as sectional view, barrel according to the feelings map.Progressively main geology key element of geological record and physical prospecting achievement are reflected on the figure in the lump with engineering progress during establishment, and repair the volume engineering geological profile according to the geological condition that excavation discloses.

4. collection drilling data

But the physical prospecting means show that when front of tunnel heading had coal seam or other unfavorable geology structure, the construction part of horizontal was surveyed boring, because of borehole data the most intuitive and reliable.

5. writing phase property geology is summed up and step geology prediction and suggestion down

In sum, in the constructing tunnel process, from start to finish carry out the geological syntheses analysis, with timely guiding construction, for the science construction organization provides geologic basis.

Two, physical prospecting means

(1) TSP method

TSP (Tunnel Seismic Prediction) method is the earthquake prediction of the place ahead, tunnel, belongs to multi-wave and multi-component high-resolution seismic exploration reflection wave Detection Techniques.Its ultimate principle is an echo principle of having used vibrations (ripples).

1. detection method

The seismic signal that is caused by micro-explosion is respectively along different approach, form with direct wave and reflection wave arrives sensor, compare with direct wave, the travel-time that reflection wave needs is longer, and the TSP system becomes seismic wave propagation speed by the longitudinal wave propagation time conversion that directly arrives sensor from focus that records:

V _p＝X ₁/T ₁ (1)

In the formula: X ₁---blast hole is to the distance of sensor; T ₁---the travel-time of direct wave.

Under known propagation of seismic wave speed, just can derive reflecting interface and accept the distance of sensor, and in the distance of tunnel cross-section, its theoretical formula be by the reflection wave travel-time that records:

T ₂＝(X ₂+X ₃)/V _P＝(2X ₂+X ₁)/V _P (2)

T in the formula ₂---the reflection wave travel-time; X ₂---the distance of blast hole and reflecting interface; X ₃---the distance of sensor and reflecting interface.

The seismic reflection wave amplitude is relevant with the reflection coefficient of reflecting interface, and under simple situation, when plane simple harmonic wave impinged perpendicularly on the plane, echo amplitude on it and transmitted wave amplitude were respectively:

$\frac{A_r}{A_i}=\frac{{\mathrm{\&rho;}}_2{V}_2-{\mathrm{\&rho;}}_1{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="A20091005882400201.png,A20091005882400202.png"\; state="\{\{state\}\}">V</figure-callout>}}_1}{{\mathrm{\&rho;}}_2{V}_2+{\mathrm{\&rho;}}_1{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="A20091005882400201.png,A20091005882400202.png"\; state="\{\{state\}\}">V</figure-callout>}}_1}=R---\left(3\right)$

$\frac{A_l}{A_i}=\frac{2{\mathrm{\&rho;}}_1{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="A20091005882400201.png,A20091005882400202.png"\; state="\{\{state\}\}">V</figure-callout>}}_1}{{\mathrm{\&rho;}}_2{V}_2+{\mathrm{\&rho;}}_1{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="A20091005882400201.png,A20091005882400202.png"\; state="\{\{state\}\}">V</figure-callout>}}_1}=1-R---\left(4\right)$

In the formula: A _i-incident wave amplitude; A _r, A _l-reflection wave and transmitted wave amplitude; V ₁, V ₂The speed of-reflecting interface media of both sides; ρ ₁, ρ ₂The density of-reflecting interface media of both sides; The reflection coefficient at R-interface.

When the incident wave amplitude A _iOne regularly, echo amplitude A _rBe directly proportional with reflection R; And the wave impedance ρ of reflection coefficient and reflecting interface media of both sides ₁Relevant, mainly by the wave impedance difference decision of interface media of both sides, the absolute value of wave impedance difference is big more, then echo amplitude A for it _rJust big more, when the wave impedance of the medium II wave impedance greater than medium I, promptly seismic event is when comparatively loose medium propagates into fine and close medium, reflection R＞0, at this moment, reflection amplitude is identical with the symbol of incident amplitude, and reflection wave has identical polarity with incident wave; Otherwise, if seismic event is when comparatively fine and close medium propagates into loose medium, at this moment, reflection R＜0, the opposite in sign of reflection amplitude and incident amplitude then, so the polarity of reflection wave and incident wave is opposite, thus can clearly judge the variation of geologic body.

2. recording geometry

TSP advanced prediction recording geometry is to arrange it is in tunnel tunnel face 1 closes on the left and right sides abutment wall of hole section, as shown in Figure 2, according to the difference of its forecast purpose, selects different abutment walls.If to the forecast of tomography, according to principle of reflection, the big gun hole arrange should with the little abutment wall of the fault strike angle of cut in.The concrete arrangement requirement of its big gun hole (C1-C24) and receiver hole (B1, B2) sees the following form:

3. data acquisition

Data acquisition is to provide the firsthand information for the data processing of TSP and data interpretation.Obtain high-quality raw data, excite the system of acceptance, also need to resolve four problems: the exciting and the interference of reception and environment of the design of recording geometry, seismic event seismic event except the TSP instrument itself provides high-sensitive data.

4. inversion technique

Reflecting interface and determining of plastid scale poorly, its principle is seen Fig. 3: at an A ₁, A ₂, A ₃Deng the position explosive source. α is the poorly angle of depression of plastid, i.e. main dip; β is the angle of the trend and the tunnel working direction of bad plastid; γ is a Space Angle, i.e. the angle of tunnel axis and unfavorable geology body interface.The seismic event that produces runs into unfavorable geology body interface (being the wave impedance interface), reflection takes place and by Q ₁The sensor of position receives.When calculating, utilize the reversibility of ripple, can think Q ₁The seismic event that send the position passes to A through the unfavorable geology boundary reflection ₁, A ₂, A ₃Deng point, can think that ripple is from picture point IP (Q ₁) send and directly pass to A ₁, A ₂, A ₃Deng what put.The Q of this moment ₁And IP (Q ₁) about unfavorable geology interface (wave impedance face) symmetry. because of Q ₁, A ₁, A ₂, A ₃The volume coordinate of each point is known, can get picture point IP (Q by simultaneous equations ₁) volume coordinate, again by Q ₁And IP (Q ₁) volume coordinate obtain the space equation of 2 place straight lines. because the unfavorable geology interface is line segment Q ₁IP (Q ₁) middle vertical plane, so can obtain the space equation of this unfavorable geology interface, further can obtain the intersection point of unfavorable geology interface and tunnel axis and the angle of cut at tunnel axis and unfavorable geology interface with respect to true origin Q. by the coordinate S of two reflectings surface of poorly plastid on the axis, tunnel that obtains ₁And S ₂Thereby, obtain the poorly scale of plastid: S=|S ₁-S ₂|.

By the longitudinal wave velocity v that records _pWith transverse wave speed v _sUtilization is used different experimental formulas at metamorphosed rock, volcanics, plutonite and sedimentogeneous rock four rocks types, and TSPWin software can obtain rock density ρ, obtains each dynamic parameter according to following formula then.

The dynamic modulus of elasticity:

$E=\mathrm{\&rho;}{v}^2\frac{3v_p^2-{2v}_s^2}{v-\frac{1}{3}{v}_s^2}---\left(5\right)$

Poisson ratio:

$\frac{v_p^2-{2v}_{\mathrm{\&lambda;}}^2}{2(v_p^2-v_s^2)}---\left(6\right)$

Bulk modulus:

$\mathrm{\&rho;}(v_p^2-\frac{4}{3}{v}_s^2)---\left(7\right)$

In the formula: Lame's constant $A=P(v_p^2-2v\frac{2}{s});$ Modulus of shearing: $\mathrm{\&mu;}=p{v}_s^2.$

Geologic prediction with left line LK16+865～LK16+733 segment limit is an example: this geology advanced prediction mileage scope mainly is in the alluvial gold dam in tiltedly, is subjected to F10 fault belt and synclinal axis portion fold compressive belt, and lithology is that mud stone is the main folder sandstone.Be subjected to structure influence very serious, the rock mass extruding is strong, and joint fissure is grown, fragmentation.Rock mass is rubble shape structure or the broken shape mosaic texture of piece.Footwall has the interlayer piestic water and is strand shape crevice water or trickle appearance.

According to TSP ratio juris and working experience, is the reflection wave groups interpretation near apart from tunnel axis, that energy is big the country rock exceptions area, and comprehensively parameters such as wave speed of the earthquake, reflection wave phase place, Poisson ratio and kinetic Youngs modulus are divided the country rock exceptions area, and the final analysis conclusion is as follows:

This face 1 mileage that gives the correct time in advance is LK16+865, and forecast mileage scope is LK16+865～LK16+733, promptly forecasts face 1 the place ahead 132m, and conclusion is as follows: LK16+865～LK16+838 section rock crusher, joint fissure are grown; LK16+838～LK16+806 section country rock is broken; LK16+806～LK16+803 section rock crusher, joint fissure are grown or weak intercalated layer; LK16+803～LK16+773 section country rock is broken, and wherein there is one group of joint fissure in LK16+795～LK16+793; LK16+773～LK16+760 section rock crusher, joint fissure growth, moisture～Fu Shui; LK16+760～LK16+733 section country rock is broken, moisture.

(2) HSP method

HSP acoustic reflection method construction geology advanced prediction and seismic event detection principle based on the geology method are basic identical, and its principle is to be based upon on the basis of elastic wave theory, and communication process is followed Huygens-Frensel principle and Fermat principle.Theoretical research and facts have proved, the sound wave velocity of propagation and the configuration state of constituent, density, elastic modulus and the rock mass of parameter such as amplitude and rock soil mass etc. in rock soil mass is relevant.When having the interface of two kinds of different solid dielectrics in the acoustic wave propagation path, wave propagation will reflect, reflection and wave mode are changed.When sound wave is transmitted to the shatter belt of fragmented rock or local soil type's one-tenth by complete rock mass, be exactly the typical case of sound wave from the high impedance medium to the Low ESR medium.By surveying reflection wave signal, obvious with the difference in acoustic properties of peripheral geologic body according to plastid (band) poorly as tomography, detrition band, underground water zone of enrichment etc., just can understand the situation of change of the place ahead rock mass.

During test, a bit launch the low-frequency sound wave signal, receive reflection wave signal at another point at tunnel construction tunnel face or abutment wall.Adopt time domain, frequency-domain analysis to survey reflection wave signal, further infer the forecasting procedure of front of tunnel heading geologic condition according to tunnel construction tunnel face geologic examination, surface geology investigation, just can understand the situation of change of the place ahead rock mass, lithology boundary, tomography, rock crushing band, weak intercalated layer and the karst etc. that the detection front of tunnel heading may exist are scale, character and the extension situation etc. of plastid poorly.

Advanced prediction has adopted ZGS1610-2 type intelligence engineering to survey sonic apparatus, advanced prediction software adopt ZGS1610-2 type intelligence engineering survey sonic apparatus collection in worksite software, with the special-purpose reflectance spectrum analysis and the reflection wavelet analysis software of this instrument image data coupling, in conjunction with the geology investigation method, implement " based on the geology method, be the complex geophysical prospecting technology of main means with HSP acoustic reflection method ", guaranteed to survey fast, data accurately and analysis result reliably.

The on-the-spot test method adopts passage to trigger one one mode of receiving and goes on a journey.Knock timber with sledgehammer and make vibration source triggering transducer, another transducer is received signal simultaneously, and signals collecting and data storing are all controlled by portable computer.

Three, advance borehole

The horizontal drilling method is the most direct means of short-term advanced prediction.It is to edit and record by boring coring, and formation lithology, structure, country rock rank, the property of water-bearing that the front of tunnel heading left and right sides is exposed, the position, the scale that contain structure of coal etc. are made more accurately and being judged.For the geologic prediction of coal measure strata, advance borehole can realize:

1) coal seam distribution, trend and detecting thickness;

2) the place ahead rock mass gas bearing situation is surveyed and the gas prediction of gushing out;

3) rock mass gas pressure, gas bearing capacity, sudden prediction such as gush out.

When adopting above-mentioned means analysis-by-synthesis to determine that front of tunnel heading has that poorly plastid exists, should adopt horizontal drilling checking back construction.

Drilling depth should be controlled at 30～50m, to reduce the face holding time; The boring layout should poorly the output scale of plastid, spread form etc. be definite according to weather report, generally should adopt triangular arrangement, make the probing achievement representative.

1, coal exploration

The coal seam is any irregular curved surface on a large scale, but near the tunnel among a small circle in, can suppose that the coal seam is the plane, establish its equation and be:

Ax+By+z+C＝0 (4.8)

If exploration hole is three, then it sees that the coal point coordinate is: A ₁(x ₁, y ₁, z ₁), A ₂(x ₂, y ₂, z ₂), A ₃(x ₃, y ₃, z ₃).

Then the equation of coal bed is:

$\left|\begin{array}{ccc}x& y& z\\ x_1& y_1& z_1\\ x_2& y_2& z_2\\ x_3& y_3& z_3\end{array}\right|=0---\left(4.9\right)$

The coordinate axis regulation: the tunnel piercing direction is the y axle; Right side, excavation face bottom cross-sectional direction is the x axle; Upwards be the z axle.

The plane equation of formula (4.9) for utilizing three leading inspecting holes to obtain, and only can not accurately determine the position, coal seam with the data of three exploration holes, because the coal seam is not the plane of a strictness, and exploration hole see coal point often outside the border, tunnel the distance far away, the tunnel piercing of Tui Suaning sees that coal point often has sizable error thus.In order accurately to determine thickness of coal seam and position, except that exploration hole, should utilize the parameter of gas prediction, discharge orifice, determine the plane equation in coal seam jointly.At this moment, desirable coal face equation should satisfy coal face to each inspecting hole and crosses coal point and hang down apart from the condition of quadratic sum minimum.With the principle of minimizing, can try to achieve every coefficient of formula (4.8).

$A=\frac{(\mathrm{\&Sigma;}{z}_i{y}_i-\stackrel{\&OverBar;}{z}\mathrm{\&Sigma;}{y}_i)(\mathrm{\&Sigma;}{x}_i{y}_i-\stackrel{\&OverBar;}{y}\mathrm{\&Sigma;}{x}_i)-(\mathrm{\&Sigma;}{y}_i^2-\stackrel{\&OverBar;}{y}\mathrm{\&Sigma;}{y}_i)(\mathrm{\&Sigma;}{z}_i{x}_i-\stackrel{\&OverBar;}{z}\mathrm{\&Sigma;}{x}_i)}{(\mathrm{\&Sigma;}{x}_i^2-\stackrel{\&OverBar;}{x}\mathrm{\&Sigma;}{x}_i)(\mathrm{\&Sigma;}{y}_i^2-\stackrel{\&OverBar;}{y}\mathrm{\&Sigma;}{y}_i)-(\mathrm{\&Sigma;}{x}_i{y}_i-\stackrel{\&OverBar;}{x}\mathrm{\&Sigma;}{y}_i)(\mathrm{\&Sigma;}{x}_i{y}_i-\stackrel{\&OverBar;}{y}\mathrm{\&Sigma;}{x}_i)}---\left(4.10\right)$

$B=\frac{\stackrel{\&OverBar;}{z}\mathrm{\&Sigma;}{x}_i-\mathrm{\&Sigma;}{x}_i{z}_i}{\mathrm{\&Sigma;}{x}_i{y}_i-\stackrel{\&OverBar;}{y}\mathrm{\&Sigma;}{x}_i}-A\&CenterDot;\frac{\mathrm{\&Sigma;}{x}_i^2-\stackrel{\&OverBar;}{x}\mathrm{\&Sigma;}{x}_i}{\mathrm{\&Sigma;}{x}_i{y}_i-\stackrel{\&OverBar;}{y}\mathrm{\&Sigma;}{x}_i}---\left(4.11\right)$

C＝-z-Ax-By (4.12)

In the formula: x _i, y _i, z _iFor each inspecting hole is seen the coal point coordinate, x, y, z are the mean value of these coordinates.

The coal seam calculation of parameter:

The inclination angle: $\mathrm{\&theta;}=\arccos \frac{1}{\sqrt{A^2+B^2+1}}---\left(4.13\right)$

Bearing and tunnel center line angle:

β＝arctgB (4.14)

Thickness of coal seam:

$d=\frac{1}{n}\mathrm{\&Sigma;}{d}_i---\left(4.15\right)$

$d_i=\frac{|{\mathrm{Ax}}_i+{\mathrm{By}}_i+z_i+D|}{\sqrt{A^2+B^2+C^2}}---\left(4.16\right)$

2, gas boring and surveying

After drilling construction is finished the gas pressure of the place ahead coal and rock, boring gas flow, the boring gas attenuation coefficient of gushing out of gushing out is measured investigation, and calculate tunnel issuable gas emission in digging process.

Gas pressure is investigated and is adopted state-of-the-art active quick pressure testing method in the world today, and its pressure measurement time only is equivalent to 0.56% of traditional pressure testing method, and pressure measurement accuracy rate and success ratio all are higher than traditional pressure testing method far away.

The boring gas emission, and the boring gas attenuation coefficient of gushing out adopts volumeter to measure calculating.

Accuracy in order to reduce detection time and to guarantee to test adopts fast dried expansive cement injection hole sealing technology.Its material mixture ratio is: 525 portland cements: high-alumina cement=3: 1 (weight ratio).

Four, excavation checking

After geological analysis, physical prospecting and leading probing, front of tunnel heading geology is made the analysis-by-synthesis forecast, behind excavation, compare, carry out system summary.

Five, brief summary

1. based on macroscopical geological analysis, geologic examination, physical prospecting and advance borehole are means, and several different methods is verified mutually and replenished, and makes up coal measure strata advanced prediction system.

2. in the constructing tunnel process, geological analysis, physical prospecting achievement, results of drilling three are organically combined, carry out the geological syntheses analysis, timely guiding construction is for the science construction organization provides geologic basis.

3. geophysical prospecting method TSP in the advanced prediction work and HSP test shows, under the situation that geologic background is analysed in depth, these two kinds of methods have suitable reliability aspect the tectonic structure differentiating.Geological analysis combines with geophysical prospecting method, can obtain the better prediction effect.

4. for the distribution and the trend in coal seam, must adopt advance borehole just must obtain reliable predicting the outcome.

Claims (6)

1, a kind of geological prediction system for constructing tunnel passing through coal measure strata is characterized in that: adopt following steps:

Step 1, macroanalysis: consult a large amount of prospecting data, design drawing, geological condition to the engineering district is more comprehensively understood, by analysis to the data in early stage, and in conjunction with the distribution of holding coal measure strata is generally summed up in the forecast and the actual contrast of excavation of the section of digging a hole;

Step 2 is made a concrete analysis of the tunnel passing through coal measure strata situation by employing geological record, physical prospecting analysis or advance borehole means on the basis of macroanalysis as the case may be;

Described geological record is in the tunnel or during wide open digging, stratum, lithology, tectonic structure, underground water and other unfavorable geology phenomenon that discloses is reflected in strictly according to the facts that barrel is showed or truncation figure on, and contrast with the tunnel longitudinal diagram;

Described physical prospecting analysis is to adopt TSP and HSP advanced prediction method to verify mutually, tentatively judges the intact condition than big abnormal conditions and rock mass that may exist in front of tunnel heading 0～150m scope;

Described advance borehole is to find out parameters such as bearing, inclination angle, thickness by the advance borehole test in the excavation when near the coal seam.

Step 3, the information classification that step 1 and step 2 are obtained is also carried out prediction of major project geologic condition and passing through coal measure strata geological hazards prediction;

Described major project geologic condition prediction comprises: lithology and the prediction of country rock integrality, tomography prediction, coal seam prediction, underground water condition predicting;

Described passing through coal measure strata geological hazards prediction comprises: landslide prediction, gas outbursts Prediction.

Step 4, integrating step 1,2,3 relevant informations of being obtained and data are finished the structure of geological prediction system for constructing tunnel passing through coal measure strata.

2. a kind of geological prediction system for constructing tunnel passing through coal measure strata according to claim 1, it is characterized in that: press the different of engineering project geologic feature and main geological problem, establishment log sheet, coal seam distribution plan, excavation comparison diagram, progressively main geology key element of geological record and physical prospecting achievement are reflected on the correlogram in the lump with engineering progress during establishment, and repair the volume engineering geological profile according to the geological condition that excavation discloses.

3. a kind of geological prediction system for constructing tunnel passing through coal measure strata according to claim 1, it is characterized in that: drilling depth is controlled at 30～50m in described advance borehole, and boring arranges that poorly output scale, the spread form of plastid are determined according to aforementioned forecast.

4. according to claim 1 or 3 described a kind of geological prediction system for constructing tunnel passing through coal measure strata, it is characterized in that: the core that drills through in the described advance borehole is write and is left in the special core case by professional geological personnel.

5. a kind of geological prediction system for constructing tunnel passing through coal measure strata according to claim 1 is characterized in that: the content that described macroanalysis comprises is: regional stability, tectonic structure, formation lithology, topography and geomorphology, texture of coal seam.

6. a kind of geological prediction system for constructing tunnel passing through coal measure strata according to claim 1 is characterized in that: the content that described geological record comprises is: face mapping, barrel mapping and geologic examination.

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