CN111551427B - Advanced quantitative prediction method for large deformation of soft rock of deep-buried long tunnel - Google Patents

Advanced quantitative prediction method for large deformation of soft rock of deep-buried long tunnel Download PDF

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CN111551427B
CN111551427B CN202010328971.4A CN202010328971A CN111551427B CN 111551427 B CN111551427 B CN 111551427B CN 202010328971 A CN202010328971 A CN 202010328971A CN 111551427 B CN111551427 B CN 111551427B
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deformation
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rock mass
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CN111551427A (en
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黄书岭
丁秀丽
王旭一
张雨霆
何军
付敬
秦洋
赵化蒙
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Changjiang River Scientific Research Institute Changjiang Water Resources Commission
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
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    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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Abstract

The invention discloses a deep-buried long tunnel soft rock large deformation advanced quantitative prediction method, which considers the quantitative prediction of far, middle and near distance positions in front of a tunnel face of a soft rock stratum which possibly appears in front of the tunnel face in the construction period; visual judgment and prediction data are obtained through surrounding rock large deformation judgment and surrounding rock deformation prediction, the deformation magnitude of the soft rock of the deep-buried long tunnel (tunnel) and the corresponding large deformation level are quantitatively predicted, and a basis is provided for the optimal design and construction scheme determination of the soft rock support of the deep-buried long tunnel.

Description

Advanced quantitative prediction method for large deformation of soft rock of deep-buried long tunnel
Technical Field
The invention relates to a quantitative prediction method for large deformation of soft surrounding rock of a tunnel, in particular to an advanced quantitative prediction method for large deformation of soft rock of a deeply-buried long tunnel.
Background
For line engineering such as traffic tunnels, diversion tunnels and the like which cross mountains, long lines and large buried depths are required to pass through strata with complicated and changeable lithological and geological conditions, and particularly when the tunnels encounter soft rock masses such as argillaceous rocks, altered rocks, fault extrusion zones and the like, the tunnel often faces engineering problems such as large deformation of the soft rock, damage of a supporting structure, large difficulty in surrounding rock reinforcement and the like in the construction period. Generally, limited geological exploration work before line engineering construction cannot completely cover information of a stratum penetrated by a tunnel (tunnel), so that the advance quantitative forecasting work of soft rock is very necessary for the stratum in front of a tunnel face of the tunnel (tunnel) in the construction period, and the method has important engineering significance.
Quantitative prediction of tunnel surrounding rock deformation is an important subject of underground engineering. The development of the detection of the poor geologic body in front of the tunnel face is a necessary link in the construction process of tunnel (tunnel) engineering. Generally speaking, the advanced geological forecast principle of the medium-long distance (100 m ahead of the tunnel face) detection based on the seismic method or the electromagnetic method needs an engineer with a geophysical professional background to interpret a detection result, so as to give a rough judgment whether a bad geological body exists in front of the tunnel face; the close-range (within 60m in front of the tunnel face) detection mostly adopts an advanced drilling method, and visual description of the geologic body in front of the tunnel face is visually obtained through drilling and coring. However, the information of the front geologic body obtained by medium-distance and short-distance detection only provides qualitative descriptions of the position, the properties and the like of the poor geologic body in front of the tunnel face for engineers, is difficult to be used for quantitative prediction and forecast of surrounding rock deformation, and cannot provide quantitative basis for dynamic adjustment of support measures. Therefore, the method for the advanced quantitative prediction of the large deformation of the soft rock of the deeply-buried long tunnel is established, and has important significance for guaranteeing the stability of surrounding rocks in the construction period of tunnel (tunnel) engineering.
Disclosure of Invention
Aiming at the problems, the invention provides an advanced quantitative prediction method for the large deformation of the soft rock of the deeply-buried long tunnel, which carries out the advanced prediction work of the soft rock on the stratum in front of the tunnel face of the tunnel in the construction period.
In order to achieve the purpose, the invention designs a deep-buried long tunnel soft rock large deformation advanced quantitative prediction method, which is characterized by comprising the following steps:
the method comprises the following steps: medium and long distance advanced stratum information forecasting technology: detecting stratum information with a set distance in front of a tunnel face by adopting a tunnel advanced geological prediction system, obtaining three-dimensional space data, and interpreting and forecasting the properties, the positions and the scale of the stratum in front of the tunnel face by utilizing a signal interpretation technology integrating a tunnel reflected wave forward modeling technology facing different-scale deformation mass structures of soft rock, a data processing technology of wave field separation and migration imaging, an earthquake data amplitude-preserving imaging method and a nonlinear intelligent inversion method based on deep learning;
step two: short-distance advanced geological drilling forecasting technology: on the basis of the work of the first step, when the tunnel is excavated to the range of 30-60 m of soft rock, drilling a pilot hole on the tunnel face;
step three: performing in-situ crustal stress test on the drilling part in the step two to obtain a three-dimensional initial stress distribution state, a maximum horizontal side pressure coefficient lambda and an initial maximum main stress value sigma at the position 0max A parameter;
step four: sampling rocks at the drilling part in the step two, carrying out an indoor physical mechanical test, and accurately mastering the physical mechanical properties of the soft rocks in front of the tunnel face;
step five: performing drilling television work on the drilling part in the step two to obtain the burial depth, inclination angle, width, roughness of the crack surface and properties of the filler of the soft rock crack, and performing field sound wave test work on the sound wave test sampling part of the rock in the step four to obtain the elastic longitudinal wave velocity V of the rock mass pm Combining the rock elastic longitudinal wave velocity V obtained by the four-step indoor test pr Calculating the integrity coefficient of rock mass
Figure BDA0002464250820000021
Step six: according to indoor tests and field tests, determining the basic quality grading of the rock mass, and further determining the physical and mechanical parameters of the soft rock mass in front of the tunnel face: grading the basic quality of the rock mass, determining the basic quality index BQ of the rock mass according to the qualitative characteristic of the basic quality of the rock mass, and determining the cohesive force c of the rock mass, the internal friction angle phi of the rock mass and the deformation modulus E of the rock mass according to the basic quality grade of the rock mass;
step seven: the tunnel surrounding rock large deformation prediction technology comprises the following steps: calculating the strength-stress ratio of the soft rock under the self-weight stress field or the structural stress field, and judging and predicting whether the surrounding rock can generate large extrusion deformation by using a surrounding rock large deformation judging method;
step eight: and on the basis of the seventh step, if the large deformation of the surrounding rock is judged to occur, rapidly and quantitatively forecasting the deformation magnitude and the relative deformation of the surrounding rock by using a quantitative forecasting formula of the deformation and the relative deformation of the surrounding rock, which is corrected by considering the supporting effect, through a steepest descent method, and giving a large deformation grade, thereby providing a basis for the optimal design and construction scheme of the soft rock support.
Preferably, in the third step, in-situ ground stress is tested, a three-way strain gauge is adopted as a testing instrument, a stress relieving method is adopted as a testing method, and cement mortar is added into the hole to serve as a coupling medium.
Preferably, the rock laboratory test in step four comprises: carrying out rock saturated uniaxial compression test to obtain rock saturated uniaxial compressive strength R c And poisson's ratio μ; performing a rock saturated triaxial compression test to obtain an expansion gradient eta; performing indoor rock sound wave test to obtain rock elastic longitudinal wave velocity V pr 。
Preferably, the calculation formula of the basic quality index BQ of the rock mass in the step six is BQ =100+3R c +250K v Using this formula, the following constraints are followed: (1) When R is c ＞90K v At +30, with R c ＝90K v +30 and K v Calculating the BQ value; (2) When K is v ＞0.04R c At +0.4, with K v ＝0.04R c +0.4 and R c Substituting to calculate a BQ value; in the formula R c The uniaxial saturated compressive strength of the rock is obtained; k v Is the integrity coefficient of the rock mass.
Preferably, the formula of the rock strength stress ratio under the self-weight stress field (lambda is less than or equal to 1) or the tectonic stress field (lambda is more than 1) in the step seven is respectively
Figure BDA0002464250820000031
In the formula, R c The rock saturated uniaxial compressive strength; sigma 0max Is the initial maximum principal stress value.
Preferably, the tunnel soft rock hole peripheral deformation quantitative prediction in the step eight is carried out by a formula
Figure BDA0002464250820000041
Obtaining through quantitative calculation; wherein R' is the plastic radius, and the calculation formula is
Figure BDA0002464250820000042
r 0 Is the tunnel radius; sigma c The uniaxial compressive strength of the rock mass is calculated by the formula
Figure BDA0002464250820000043
Figure BDA0002464250820000044
c is the cohesion of the rock mass,
Figure BDA0002464250820000045
is the internal friction angle of the rock mass; wherein
Figure BDA0002464250820000046
Figure BDA0002464250820000047
P is the vertical initial stress; lambda is the maximum horizontal side pressure coefficient; eta is the expansion gradient; reflecting theta angles of different positions of the surrounding rock; e is the deformation modulus of the rock mass; mu is Poisson's ratio; p is i The supporting resistance is realized.
Preferably, when multiple support forms are considered in the step eight, the support resistance P is considered i By the formula
Figure BDA0002464250820000048
Quantization determination; wherein E c Is the modulus of elasticity of the concrete; r is the outermost radius of the support; s. the 1 The distance between the steel arches distributed along the axis of the tunnel; s 2 The distance between the reinforcing steel bars distributed along the axis of the tunnel;S c the distance between the anchor rods is distributed along the circumference of the tunnel; s l The distance between the anchor rods is distributed along the axis of the tunnel; a. The s1 Is the cross-sectional area of the steel arch; a. The s2 The cross-sectional area of the steel bar in the tunnel cross section is shown; e s1 Is the modulus of elasticity of steel; e s2 The elastic modulus of the anchor rod and the anchor cable is shown; v. of c Is the poisson's ratio of the concrete; t is t c Is the thickness of the concrete; t is t B The thickness of the steel arch ring is supported; b is the flange width of the channel steel or the angle steel; i is s Is the moment of inertia of the tunnel cross section; theta is a semiradian of an included angle of the two stop block nodes; e B The elastic modulus of the block material; d is the average thickness of the concrete filled in the overbreak area; wherein d is b The diameters of the anchor rods and the anchor cables are adopted; l is the free length of the anchor rod and the anchor cable; and Q is the deformation load constant of the end part and the head part of the anchor rod.
Preferably, the method for judging the large deformation of the surrounding rock in the seventh step is obtained by quantitative calculation of the relative deformation epsilon, when the relative deformation epsilon is more than 2.5 percent and less than 5 percent, the surrounding rock is the I-level large deformation, and the deformation degree is medium; when the relative deformation is more than 5 percent and less than 10 percent, the deformation is large in II-grade surrounding rock, and the deformation degree is serious; when the relative deformation epsilon is more than 10 percent, the deformation is large in class III surrounding rock, and the deformation degree is extremely serious.
Due to the adoption of the technical scheme, quantitative prediction work at far, middle and near distances in front of the tunnel face is considered at the same time, and the method is a deep-buried long tunnel soft rock large deformation advanced prediction method; visual judgment and prediction data are obtained by judging the large deformation of the surrounding rock and predicting the deformation of the surrounding rock, the deformation magnitude and grade of the soft rock of the deeply-buried long tunnel (tunnel) are quantitatively predicted, and the advanced prediction and prediction work of the soft rock is effectively carried out.
Drawings
FIG. 1 is a flow chart of the advanced quantitative prediction method for large deformation of soft rock in a deep-buried long tunnel according to the present invention.
Fig. 2 is a schematic diagram of the concrete support lining of the present invention.
FIG. 3 is a schematic diagram showing the deformation magnitude and relative deformation of tunnel surrounding rock and the corresponding large deformation level when the initial vertical ground stress is 4-30 MPa under different burial depths.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
As shown in fig. 1, the advanced quantitative prediction method for large deformation of soft rock in a deep-buried long tunnel provided by the invention comprises the following steps:
the method comprises the following steps: medium and long distance advanced stratum information forecasting technology. The method comprises the steps of selecting a TRT7000 tunnel advanced geological prediction system or a TEP tunnel advanced geological prediction system developed by the university of Yangtze river to detect medium-long distance (100 m) stratum information in front of a tunnel face and obtain three-dimensional space data, and interpreting and predicting the properties (such as joint fracture zones, weak zones, fault fracture zones and the like), the position and the scale of the stratum in front of the tunnel face of the tunnel by utilizing a tunnel reflected wave forward modeling technology for soft rock different-scale deformed body, a wave field separation and offset imaging data processing technology, a seismic data amplitude-preserving imaging method and a signal interpretation technology integrating a deep learning-based nonlinear intelligent inversion method.
Step two: and (3) excavating the tunnel under the assistance of feedback analysis of a TEP system, drilling advanced holes on the tunnel face by adopting a short-distance advanced geological drilling forecasting technology when the tunnel is excavated to the range of 30-60 m away from the soft rock on the tunnel face, and generally dispersedly laying 3-6 drilled holes on the tunnel face and drilling along the axial direction of the tunnel. Determining the geology ahead of the face by drilling exposure, specifically: the occurrence condition of front underground water can be judged according to the water outlet and the water outlet amount of the drill hole; the drilling speed can reflect the hardness degree of the front soft rock; the core sampling rate can reflect the development condition of the front fracture and the like.
Step three: and carrying out in-situ ground stress test on the drilling part in the second step. The testing instrument can adopt a three-way strain gauge, the testing method can adopt a stress relief method, and cement mortar is added into the hole to be used as a coupling medium. Obtaining the three-dimensional initial stress distribution state, the maximum horizontal side pressure coefficient lambda and the initial maximum main stress value sigma 0max And judging that the stress environment of the lower cavern is a self-weight stress field when the lambda is less than or equal to 1,and when lambda is more than 1, the stress environment of the lower cavity is a structural stress field.
Step four: and sampling rocks at the drilling part in the step two, carrying out an indoor physical mechanical test, and accurately mastering the physical mechanical properties of the soft rocks in front of the tunnel face. After sampling on site, processing the core into a cylindrical test piece with the height-diameter ratio of 1: 2, and taking the diameter of 50mm and the height of 100mm. Specifically, indoor rock sound wave test is carried out to obtain rock elastic longitudinal wave velocity V pr (ii) a Carrying out rock saturated uniaxial compression test after saturation treatment to obtain rock saturated uniaxial compression strength R c Poisson ratio mu; and performing a rock saturated triaxial compression test after saturation treatment to obtain an expansion gradient eta.
Step five: and D, performing drilling television and sound wave test work on the drilling part in the step two. Adding water into the hole as a coupling medium, acquiring a 360-degree image of the wall of the drill hole from the hole opening to the hole bottom by using a drill television, and performing digital processing to obtain the properties of the soft rock fracture such as buried depth, inclination angle, width, roughness of the fracture surface, filling and the like. The sound wave test adopts a single-transmitting single-receiving cross-hole sound wave instrument (or a single-transmitting double-receiving single-hole sound wave instrument), a dry hole transducer is preferably adopted in soft rock, and the field sound wave test work is carried out at the sound wave test sampling part of the rock in the step four, so as to obtain the elastic longitudinal wave velocity V of the rock mass pm Combining the rock elastic longitudinal wave velocity V obtained by the four-step indoor test pr Calculating the integrity coefficient of rock mass
Figure BDA0002464250820000071
Step six: according to indoor tests and field tests, basic quality grading of the rock mass is determined, and physical and mechanical parameters of the soft rock mass in front of the tunnel face are further determined.
The basic quality grading of the rock mass is determined according to the qualitative characteristics of the basic quality of the rock mass and the basic quality index (BQ) of the rock mass. The qualitative characteristics of the basic quality of the rock mass are determined according to the hardness degree of the rock and the integrity degree of the rock mass which are evaluated on site; the calculation formula of basic quality index (BQ) of rock mass is BQ =100+3R c +250K v When this formula is used, the following constraints should be observed: (1) When R is c ＞90K v At +30, R should be c ＝90K v +30 and K v Calculating the BQ value; (2) When K is v ＞0.04R c At +0.4, K should be added v ＝0.04R c +0.4 and R c Substituting to calculate BQ value. In the formula R c For uniaxial saturated compressive strength, i.e. sigma, of rock c ；K v Is the integrity coefficient of the rock mass.
Determining the cohesive force c and the internal friction angle of the rock mass according to the basic quality level of the rock mass
Figure BDA0002464250820000072
And the rock mass deformation modulus E.
Step seven: a large deformation quantitative forecasting technology for tunnel surrounding rock. In-situ maximum principal stress value sigma is obtained in step three 0max And step four, obtaining the rock saturated uniaxial compressive strength R of the cylindrical rock sample c And then calculating the strength stress ratio of the soft rock under the dead weight stress field or the tectonic stress field. Rock strength stress ratio under self-weight stress field (lambda is less than or equal to 1) or structural stress field (lambda is more than 1)
Figure BDA0002464250820000081
Then adopt
Figure BDA0002464250820000082
And judging whether the large buried depth cavern can generate surrounding rock extrusion large deformation. And when the SSR is larger than 1, judging that the large deformation of the surrounding rock extrusion cannot occur, otherwise, judging that the large deformation of the surrounding rock extrusion can occur. If the surrounding rock extrusion large deformation occurs, predicting and forecasting the deformation magnitude of the surrounding rock; and if the surrounding rock is judged not to be extruded and deformed greatly, the supporting design is optimized and the supporting strength is reduced.
Step eight: and on the basis of the seventh step, if the large deformation of the surrounding rock is judged to occur, rapidly and quantitatively forecasting the deformation magnitude and the relative deformation of the surrounding rock by using a quantitative forecasting formula of the deformation and the relative deformation of the surrounding rock, which is corrected by considering the supporting effect, through a steepest descent method, and giving a large deformation grade, thereby providing a basis for the optimal design and construction scheme of the soft rock support.
Tunnel soft rock tunnel peripheral changeForm prediction, which can be represented by the formula
Figure BDA0002464250820000083
Obtained by calculation, the derivation process of the formula is as follows:
assuming that the strain in the plastic region is axisymmetrically distributed, the plastic region geometry equation:
Figure BDA0002464250820000084
Figure BDA0002464250820000085
and considering the expansion effect of the surrounding rock during yielding, and assuming that the expansion gradient eta is a constant value. According to the flow rule η epsilon θp +ε rp =0, so there are:
Figure BDA0002464250820000086
reuse of the continuous condition U of displacement at the elasto-plastic interface rp | r＝R ＝U re | r＝R The solution can be obtained. For the supporting, the solving process of the tunnel peripheral displacement is as follows:
elastic zone stress component:
Figure BDA0002464250820000091
radial stress at the elastoplastic junction:
Figure BDA0002464250820000092
plastic radius:
Figure BDA0002464250820000093
elastic radial displacement U of the elastic region r And annular displacement U θ Respectively as follows:
Figure BDA0002464250820000094
Figure BDA0002464250820000095
elastic displacement of the elastic-plastic junction:
Figure BDA0002464250820000096
plastic zone displacement:
Figure BDA0002464250820000097
the total radial displacement around the tunnel is therefore:
Figure BDA0002464250820000098
in the formula, r 0 Is the radius of the tunnel; sigma c The uniaxial compressive strength of the rock mass is calculated by the formula
Figure BDA0002464250820000099
Figure BDA00024642508200000910
c is the cohesive force of the rock mass,
Figure BDA00024642508200000911
is the internal friction angle of the rock mass;
Figure BDA00024642508200000912
Figure BDA0002464250820000101
p is the vertical initial stress; lambda is the maximum horizontal side pressure coefficient; eta is the expansion gradient; reflecting the theta angle of different positions of the surrounding rock; e is rock massA modulus of deformation; mu is Poisson's ratio; p i The supporting resistance is realized.
When considering various supporting forms, the supporting resistance P i From the formula P i ＝(K s1 +K s2 +K s3 +K s4 )u r Determination of in the formula s1 The support stiffness coefficient of the sprayed concrete; k s2 The support stiffness coefficient of the steel arch frame; k s3 A support stiffness coefficient for the reinforced concrete lining; k s4 The support stiffness coefficient of the unbonded anchor rod is adopted. The calculation formula of the support stiffness coefficient of each support form is as follows:
for the shotcrete, it can be regarded as a closed circular ring, as shown in fig. 2, and its support stiffness coefficient is:
Figure BDA0002464250820000102
wherein E c Is the modulus of elasticity (MPa) of the concrete lining; v. of c Is the poisson's ratio of concrete; r is the outermost radius (m) of the support, and a tunnel radius can be adopted for replacing the outermost radius (m); tc is the thickness (m) of the concrete.
For steel arch support, it can be assumed that the steel arch support closely acts on surrounding rock, and the support stiffness coefficient is as follows:
Figure BDA0002464250820000103
wherein E s1 Is the modulus of elasticity (MPa) of steel (arch); r is the outermost radius (m) of the support, and a tunnel radius can be generally adopted for replacement; t is t B Thickness (m) of the steel arch ring for supporting; b is the flange width (m) of the channel steel or the angle steel; a. The s1 Is the cross-sectional area (m) of the steel arch 2 )；I s Is the moment of inertia (m) of the tunnel cross section 4 )；S 1 The distance (m) between the steel arch frames distributed along the axis of the tunnel; theta is half of the included angle (radian) of the two block nodes; e B The modulus of elasticity (MPa) of the block material.
For the reinforced concrete lining, it is similar to shotcrete, just place certain reinforcing bar in the concrete and form the reinforced concrete circle and strut the tunnel country rock, and its support rigidity coefficient is:
Figure BDA0002464250820000111
wherein E c Is the modulus of elasticity (MPa) of the concrete; d is the average thickness (m) of the concrete filled in the overbreak area; e s1 The modulus of elasticity (MPa) of the steel (bar); r is the outermost radius (m) of the support, and a tunnel radius can be generally adopted for replacement; a. The s2 Is the cross-sectional area (m) of the reinforcing steel bar in the tunnel section 2 )；S 2 The distance (m) between the reinforcing steel bars distributed along the axis of the tunnel.
For the unbonded anchor rod, the anchor rod is assumed to be uniformly distributed along the circumference, and the support rigidity coefficient is as follows:
Figure BDA0002464250820000112
wherein d is b The diameter (m) of the anchor rod and the anchor cable; l is the free length (m) of the anchor rod and the anchor cable; q is the deformation load constant of the end part and the head part of the anchor rod; e s2 The elastic modulus (MPa) of the anchor rod and the anchor cable; s c The distance (m) of the anchor rods distributed along the circumference; s l The distance (m) of the anchor rods distributed along the axis of the tunnel.
On the basis of the above, the relative deformation ε can be determined by
Figure BDA0002464250820000113
And (6) calculating. When the relative deformation is more than 2.5 percent and less than epsilon and less than 5 percent, the rock is I-grade surrounding rock large deformation, and the deformation degree is medium; when the relative deformation is more than 5 percent and less than 10 percent, the deformation is large for II-grade surrounding rock, and the deformation degree is serious; when the relative deformation epsilon is more than 10 percent, the deformation is large in class III surrounding rock, and the deformation degree is extremely serious.
Taking a deeply buried circular tunnel with a radius r0=2.965m as an example, the middle deformation modulus E of the mechanical parameters of the surrounding rock is 5GPa, the Poisson ratio is 0.3, the internal friction angle of the rock mass is 30 degrees, the cohesive force is 0.3MPa, the expansion gradient is 1, the lateral pressure coefficient is 1.25, the deformation magnitude and the relative deformation of the surrounding rock of the tunnel under different buried depth conditions when the initial vertical ground stress is 4-30 MPa are forecasted, and the corresponding large deformation magnitude when the corresponding initial vertical ground stress is given, which is shown in figure 3.
Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are only illustrative and not restrictive, and those skilled in the art can make various changes and modifications within the scope of the present invention without departing from the spirit and scope of the present invention as claimed.

Claims (4)

1. A deep-buried long tunnel soft rock large deformation advanced quantitative prediction method is characterized by comprising the following steps: the method comprises the following steps:
the method comprises the following steps: medium and long distance advanced stratum information forecasting technology: detecting stratum information with a set distance in front of a tunnel face by adopting a tunnel advanced geological prediction system, obtaining three-dimensional space data, and interpreting and predicting the property, position and scale of the stratum in front of the tunnel face by utilizing a signal interpretation technology integrating a tunnel reflected wave forward modeling technology facing different-scale deformation structure bodies of soft rock, a data processing technology of wave field separation and migration imaging, a seismic data amplitude preservation imaging method and a nonlinear intelligent inversion method based on deep learning;
step two: short-distance advanced geological drilling forecasting technology: on the basis of the work of the first step, when the tunnel is excavated to the range of 30-60 m of soft rock, drilling a pilot hole on the tunnel face;
step three: performing in-situ crustal stress test on the drilling part in the step two to obtain a three-dimensional initial stress distribution state, a maximum horizontal side pressure coefficient lambda and an initial maximum main stress value sigma at the drilling part 0max A parameter;
step four: sampling rocks at the drilling part in the step two, carrying out an indoor physical mechanical test, and accurately mastering the physical mechanical properties of the soft rocks in front of the tunnel face;
step five: performing drilling television work on the drilling part in the step two to obtain the burial depth, inclination angle, width, roughness of the crack surface and properties of the filler of the soft rock crack, and performing field sound wave test work on the sound wave test sampling part of the rock in the step four to obtain the elastic longitudinal wave velocity V of the rock mass pm Combining four experimental procedures to obtain the rock elastic longitudinal wave velocity V pr Calculating the integrity coefficient of rock mass
Figure FDA0003898962360000011
Step six: according to indoor tests and field tests, determining the basic quality grading of the rock mass, and further determining the physical and mechanical parameters of the soft rock mass in front of the tunnel face: grading the basic quality of the rock mass, determining the basic quality index BQ of the rock mass according to the qualitative characteristic of the basic quality of the rock mass, and determining the cohesive force c of the rock mass, the internal friction angle phi of the rock mass and the deformation modulus E of the rock mass according to the basic quality grade of the rock mass;
step seven: the tunnel surrounding rock large deformation prediction technology comprises the following steps: calculating the strength-stress ratio of the soft rock under the self-weight stress field or the structural stress field, and judging and predicting whether the surrounding rock can generate large extrusion deformation by using a surrounding rock large deformation judging method;
a self-weight stress field (lambda is less than or equal to 1) or a structural stress field (lambda>1) The formula of the strength-stress ratio of the rock is
Figure FDA0003898962360000021
In the formula, R c The rock saturated uniaxial compressive strength; sigma 0max Is the initial maximum principal stress value;
the method for judging the large deformation of the surrounding rock is obtained by carrying out quantitative calculation on the relative deformation epsilon, when the relative deformation epsilon is more than 2.5 percent and less than 5 percent, the method is the large deformation of the I-grade surrounding rock, and the deformation degree is medium; when the relative deformation is more than 5 percent and less than 10 percent, the deformation is large in class II surrounding rock, and the deformation degree is serious; when the relative deformation epsilon is more than 10 percent, the deformation is large in class III surrounding rock, and the deformation degree is extremely serious;
step eight: on the basis of the seventh step, if the surrounding rock large deformation is judged to occur, rapidly and quantitatively forecasting the deformation magnitude and the relative deformation of the surrounding rock by utilizing a surrounding rock deformation and relative deformation quantitative forecasting formula which considers the correction of the supporting effect and through a steepest descent method, giving a large deformation grade and providing a basis for the optimal design and construction scheme of the soft rock support;
quantitatively forecasting the peripheral deformation of the tunnel soft rock by a formula
Figure FDA0003898962360000022
Obtaining through quantitative calculation; wherein R' is the plastic radius, and the calculation formula is
Figure FDA0003898962360000023
r 0 Is the radius of the tunnel; sigma c The uniaxial compressive strength of the rock mass is calculated by the formula
Figure FDA0003898962360000024
Figure FDA0003898962360000025
c is the cohesion of the rock mass,
Figure FDA0003898962360000026
is the internal friction angle of the rock mass; wherein
Figure FDA0003898962360000027
Figure FDA0003898962360000028
P is the vertical initial ground stress; lambda is the maximum horizontal side pressure coefficient; eta is the expansion gradient; reflecting theta angles of different positions of the surrounding rock; e is the deformation modulus of the rock mass; mu is Poisson's ratio; p i Resistance of support;
when considering various supporting forms, the supporting resistance P i By the formula
Figure FDA0003898962360000031
Quantization determination; wherein E c Is the modulus of elasticity of the concrete; r is the outermost radius of the support; s 1 The distance between the steel arch frames distributed along the axis of the tunnel; s 2 The distance between the reinforcing steel bars distributed along the axis of the tunnel; s c The distance between the anchor rods is distributed along the circumference of the tunnel; s l The distance between the anchor rods is distributed along the axis of the tunnel; a. The s1 Is the cross-sectional area of the steel arch; a. The s2 The cross-sectional area of the steel bar in the section of the tunnel; e s1 Is the modulus of elasticity of steel; e s2 The elastic modulus of the anchor rod and the anchor cable is obtained; v. of c Is the poisson's ratio of concrete; t is t c Is the thickness of the concrete; t is t B The thickness of the steel arch ring is supported; b is the flange width of the channel steel or the angle steel; i is s Is the moment of inertia of the tunnel cross section; theta is a semiradian of an included angle of the two stop block nodes; e B The elastic modulus of the block material; d is the average thickness of the concrete filled in the overexcavation area; wherein d is b The diameters of the anchor rods and the anchor cables are adopted; l is the free length of the anchor rod and the anchor cable; and Q is the deformation load constant of the end part and the head part of the anchor rod.
2. The advanced quantitative prediction method for the large deformation of the soft rock of the deep-buried long tunnel according to claim 1, characterized in that: in the third step, in-situ crustal stress is tested, a three-way strain gauge is adopted as a testing instrument, a stress relieving method is adopted as a testing method, and cement mortar is added into the hole to serve as a coupling medium.
3. The advanced quantitative prediction method for the large deformation of the soft rock of the deep-buried long tunnel according to claim 1, characterized in that: the rock laboratory test in the fourth step comprises the following steps: carrying out rock saturated uniaxial compression test to obtain rock saturated uniaxial compressive strength R c And poisson's ratio μ; performing a rock saturated triaxial compression test to obtain an expansion gradient eta; performing indoor rock sound wave test to obtain rock elastic longitudinal wave velocity V pr 。
4. According to claim1, the advanced quantitative prediction method for large deformation of soft rock of the deep-buried long tunnel is characterized by comprising the following steps: the calculation formula of basic quality index BQ of rock mass in the step six is BQ =100+3R c +250K v Using this formula, the following constraints are followed: (1) When R is c ＞90K v At +30, with R c ＝90K v +30 and K v Calculating the BQ value; (2) When K is v ＞0.04R c At +0.4, with K v ＝0.04R c +0.4 and R c Substituting to calculate a BQ value; in the formula R c The uniaxial saturated compressive strength of the rock is obtained; k v Is the integrity coefficient of the rock mass.
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