CN117167085A

CN117167085A - Anchor injection supporting method for coal pillar-free mining roadway retaining

Info

Publication number: CN117167085A
Application number: CN202311003881.8A
Authority: CN
Inventors: 范钢伟; 倪惠宁; 张东升; 张世忠; 范祎博; 岳鑫; 谢文武; 陈华; 郭雪; 任尚
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2023-08-10
Filing date: 2023-08-10
Publication date: 2023-12-05

Abstract

The invention belongs to the technical field of support of a non-coal pillar mining roadway, and particularly relates to a non-coal pillar mining roadway anchor grouting support method, which is used for carrying out full-period integrated support on a roadway through a hollow high-strength grouting anchor cable, a hollow grouting anchor rod and a high-strength prestress anchor rod according to the characteristic of long-time non-uniform deformation of surrounding rock in a service period of the non-coal pillar mining roadway, and comprises the following steps: in the stoping roadway tunneling period, the roadway is anchored and supported through a construction hollow high-strength grouting anchor cable, a hollow grouting anchor rod and a high-strength prestressed anchor rod; in the stoping period of the coal face, advanced grouting and secondary tensioning pre-tightening are carried out on the advanced working face in a stoping roadway; in the stoping roadway retaining period, lagging the working face in the stoping roadway for 2-4 cycles to perform secondary grouting and tertiary tensioning pre-tightening; and the integral control of the deformation of the surrounding rock of the whole period of the drift-free mining and retaining roadway is realized through the anchor support in the tunneling period, the advanced anchor injection reinforcement in the stoping period and the re-injection reinforcement in the retaining period.

Description

Anchor injection supporting method for coal pillar-free mining roadway retaining

Technical Field

The invention belongs to the technical field of roadway support of coal pillar-free mining and entry retaining, and particularly relates to a roadway anchor injection support method of coal pillar-free mining.

Background

Aiming at the problem of controlling surrounding rock of the non-coal pillar mining roadway, the non-coal pillar mining roadway needs to undergo a driving period, a stoping period and a retaining period, the roadway service period is longer, deformation damage of the surrounding rock intensively occurs in the stoping period and the retaining period, and the deformation of the non-coal pillar mining roadway has the characteristic of non-uniform speed for a long time. If the support failure occurs in the early stage, the surrounding rock is deformed and separated, so that the later stage deformation control difficulty is increased, and a full-period deformation integrated control support method is required to be provided according to the characteristic of long-time non-uniform deformation of the roadway.

The traditional anchor rod (rope) can only ensure the stability of surrounding rock after the tunnel is excavated through the anchoring effect, and control the deformation of the surrounding rock at the initial stage and the occurrence of separation layers, but has poor control effect on the deformation of the tunnel under the conditions of crushing the surrounding rock at the subsequent stoping period and the entry retaining period; if grouting reinforcement is carried out at the later stage, the engineering quantity is increased, the production efficiency is affected, meanwhile, the ordinary anchor rods (ropes) for tunneling and supporting construction are failed, the anchor-grouting combined supporting effect is difficult to achieve, and the structural integrity of the top plate can be damaged when the too dense anchor rod (rope) is constructed again.

The grouting anchor cable support can simultaneously realize two functions of anchoring and grouting reinforcement, and is widely applied to broken surrounding rock roadway tunneling support and has good adaptability. The traditional anchor grouting support is used for grouting the broken surrounding rock tunneling roadway for one time in the tunneling period, but the coal pillar-free mining roadway entry driving roadway is complete in initial surrounding rock tunneling, grouting reinforcement is not needed and is difficult to carry out through grouting anchor cables, and grouting reinforcement is needed for surrounding rocks in the later mining period and the roadway entry driving period compared with broken surrounding rocks.

Therefore, a supporting method is required to be provided, according to the deformation and damage characteristics of the surrounding rock of the whole period of the non-coal pillar mining roadway serving, the deformation and separation layer of the surrounding rock at the initial stage of the roadway driving can be controlled, meanwhile, the broken surrounding rock at the stoping period and the roadway retaining period is subjected to advanced grouting reinforcement and reinjection, and the slurry parameters are determined according to the damage characteristics at different periods, so that the whole period deformation and integration control of the surrounding rock of the non-coal pillar mining roadway and the normal use of the roadway are realized. Aiming at the technical problem, the invention provides a method for supporting the anchor injection of the drift in the coal pillar-free mining.

Disclosure of Invention

The invention provides a method for supporting a drift-retaining anchor injection in coal pillar-free exploitation, which is characterized in that the whole period of the drift-retaining roadway in coal pillar-free exploitation is supported by the anchor injection support in the tunneling period, the advanced anchor injection reinforcement in the stoping period and the repeated injection reinforcement in the drift-retaining period so as to realize the purposes of integrally controlling surrounding rock deformation and guaranteeing the section of the roadway.

The technical scheme adopted for solving the technical problems is as follows: a method for supporting a drift-retaining anchor without coal pillar exploitation comprises the following steps:

step S1, stoping a roadway tunneling period:

carrying out laboratory mechanical property test on surrounding rock samples obtained by drilling the tunnel to obtain the mechanical parameters of the surrounding rock of the tunnel, carrying out in-situ test of the in-situ ground stress to obtain the mechanical environment of the surrounding rock of the tunnel, and carrying out drilling peeping to obtain the deformation and damage characteristics of the surrounding rock of the tunnel in the tunneling period; according to the mechanical parameters of the roadway surrounding rock, the stress environment and the deformation and damage characteristics of the roadway surrounding rock in the tunneling period, determining a tunneling period anchoring and supporting scheme adopting a hollow high-strength grouting anchor cable, a hollow grouting anchor rod and a high-strength prestressed anchor rod for supporting through theoretical calculation and numerical simulation;

S2, stoping roadway tunneling support period:

constructing a hollow high-strength grouting anchor cable, a hollow grouting anchor rod and a high-strength pre-stressed anchor rod according to the support scheme determined in the step S1, supporting a roadway, and tensioning and pre-tightening the constructed hollow high-strength grouting anchor cable, hollow grouting anchor rod and high-strength pre-stressed anchor rod to the designed pre-stress;

step S3, coal face stoping period:

in the stoping period of the coal face, on-site coal body supporting pressure monitoring, drilling peeping and roadway deformation monitoring are carried out in the roadway, and advanced supporting pressure distribution characteristics and stoping period roadway surrounding rock deformation damage characteristics are obtained; according to the advanced support pressure distribution characteristics and the deformation and damage characteristics of surrounding rock of a roadway in the recovery period, a technical scheme of advanced anchor injection support in the recovery period is provided through numerical simulation and grouting tests of advanced anchor injection support in the recovery period;

according to the technical scheme of advanced anchor grouting support in the stoping period, grouting liquid is injected into the hollow high-strength grouting anchor cable and the hollow grouting anchor rod in the step S2 within the range of 30-80 m in the stoping roadway, grouting liquid in the hollow high-strength grouting anchor cable and the hollow grouting anchor rod is discharged after grouting is finished, and secondary tensioning and pre-tightening are carried out on the hollow high-strength grouting anchor cable, the hollow grouting anchor rod and the high-strength pre-stressed anchor rod after grouting;

S4, stoping roadway retaining period:

in the stoping roadway retaining period, drilling peeping and roadway deformation monitoring are carried out in the roadway to obtain roadway surrounding rock deformation damage characteristics in the roadway retaining period, and a roadway retaining period reinjection reinforcement supporting scheme is provided according to the roadway surrounding rock deformation damage characteristics in the roadway retaining period;

according to the roadway re-grouting reinforcement support scheme in the entry retaining period, the working face is lagged by 2-4 cycles to press the step distance, secondary grouting is conducted on the hollow high-strength grouting anchor cable and the top plate of the hollow grouting anchor rod which are subjected to grouting in the step S3, and the hollow high-strength grouting anchor cable and the hollow grouting anchor rod which are subjected to secondary grouting and the high-strength prestressed anchor rod are subjected to three tensioning and pre-tightening.

In the step S1, drilling peeping is carried out on a top plate, a bottom plate and a roadway side of a roadway to obtain roadway surrounding rock deformation damage characteristics in a tunneling period, wherein the roadway surrounding rock deformation damage characteristics in the tunneling period comprise crack development density, length, width and depth of roadway surrounding rock; according to the mechanical parameters of the surrounding rock of the roadway, the stress environment and the deformation damage condition of the surrounding rock of the roadway in the tunneling period, the supporting strength is obtained through theoretical calculation, a tunneling period anchoring supporting scheme is designed, a full-period supporting numerical calculation model of the coal pillar-free mining roadway is built based on a strain softening constitutive model, the surrounding rock deformation and the plastic area distribution range of the tunneling roadway supported by the proposed tunneling period anchoring supporting scheme are analyzed, the tunneling period anchoring supporting scheme is optimized according to the numerical simulation result, and the optimized tunneling period anchoring supporting scheme comprises the diameter, the length, the pretightening force, the interval distance, the model and the number of anchoring agents and the model and the size of a tray.

As a further preferable mode of the invention, in the step S2, the hollow grouting anchor rod and the high-strength pre-stressed anchor rod are constructed according to the row spacing of 800-1000 mm, and the hollow high-strength grouting anchor cable is constructed according to the row spacing of 1600-2000 mm; in the section of the same roadway, the hollow grouting anchor rods and the high-strength prestressed anchor rods are constructed alternately; the hollow high-strength grouting anchor cable and the hollow grouting anchor rod are constructed at intervals, the hollow high-strength grouting anchor cable is positioned between two rows of hollow grouting anchor rods, one row is used for constructing 1-3 hollow high-strength grouting anchor cables, and the other row is used for constructing 2-4 hollow grouting anchor rods.

As a further preferred aspect of the present invention, in step S3, the coal body supporting pressure monitoring specifically includes drilling a hole in the advanced support section of the stoping roadway, disposing a surrounding rock stress sensor in the surrounding rock of the roadway, and actually measuring the advanced supporting pressure distribution characteristics in the roadway during the stoping, where the advanced supporting pressure distribution characteristics include the influence range, magnitude and stress concentration coefficient of the advanced supporting pressure;

the drilling peeping method comprises the specific steps of performing drilling peeping on a top plate and a roadway side of a stoping roadway in a stoping period to master the damage characteristics of roadway surrounding rocks in the stoping period, and peeping to obtain deformation damage conditions of the roadway surrounding rocks at different distances of an advanced working face, wherein the damage characteristics of the roadway surrounding rocks in the stoping period comprise crack development density, length, width and depth of the roadway surrounding rocks at different distances of the advanced working face;

The roadway deformation monitoring method specifically comprises the steps of setting a monitoring section every 50m by taking a position of a leading working surface as a starting point in a stoping period, and monitoring roadway deformation characteristics in the stoping period, wherein the roadway deformation characteristics in the stoping period comprise approaching amounts of top and bottom plates and approaching amounts of two sides of a roadway at different distances of the leading working surface;

comprehensively analyzing the surrounding rock destruction characteristics of the mining-period roadway obtained by drilling peeping and the deformation characteristics of the mining-period roadway obtained by roadway deformation monitoring, and obtaining the surrounding rock deformation destruction characteristics of the mining-period roadway;

according to the advanced support pressure distribution characteristics and the deformation and destruction characteristics of surrounding rock of the roadway in the recovery period, the surrounding rock control effect of advanced anchor injection support construction parameters on the advanced support section of the roadway is provided through advanced anchor injection support numerical simulation analysis, surrounding rock control effect evaluation indexes comprise roadway section convergence conditions and plastic region development conditions, and advanced anchor injection support construction parameters are optimized and determined according to simulation results, wherein the advanced anchor injection support construction parameters comprise grouting pressure, grouting quantity and slurry proportioning parameters; analyzing the surrounding rock control effect and the slurry diffusion effect of the grouting distances of different advanced working surfaces by performing an on-site grouting test, and determining the reasonable advanced working surface grouting distance; and the technical scheme of the advanced anchor grouting support is provided according to the advanced anchor grouting support construction parameters and the advanced working surface grouting distance.

As a further preferred aspect of the present invention, in step S3, the grouting material is cement water glass slurry, and the cement slurry has a water cement ratio of: cement (mass ratio) =1:1; using liquid water glass with wave density 37, cement slurry: water glass (volume ratio) =1:0.1-0.2.

In the step S4, during the roadway retention, the drilling peeping and roadway deformation monitoring are carried out in the roadway to obtain the deformation damage characteristics of the surrounding rock of the roadway in the roadway retention period;

the drilling peeping method comprises the specific steps of performing drilling peeping on a top plate and a roadway wall of a roadway retaining section of a stoping roadway in a roadway retaining period to master the damage characteristics of roadway surrounding rocks in the roadway retaining period, and peeping to obtain deformation damage conditions of the roadway surrounding rocks at different distances of a lagging working surface, wherein the damage characteristics of the roadway surrounding rocks in the roadway retaining period comprise crack development density, length, width and depth of the roadway surrounding rocks at different distances of the lagging working surface;

the roadway deformation monitoring method specifically comprises the following steps of continuously monitoring deformation of a monitoring section arranged in a stoping period of a roadway entry retaining period, and monitoring roadway deformation characteristics of the roadway entry retaining period, wherein the roadway deformation characteristics of the roadway entry retaining period comprise approaching amounts of top and bottom plates and approaching amounts of two sides of a roadway at different distances of a lagged working surface;

Comprehensively analyzing the surrounding rock destruction characteristics of the roadway in the roadway retaining period obtained by drilling peeping and the deformation characteristics of the roadway in the roadway retaining period obtained by monitoring the deformation of the roadway, and obtaining the deformation destruction characteristics of the surrounding rock of the roadway in the roadway retaining period;

and providing a retaining period re-injection reinforcement support scheme according to the deformation and damage characteristics of the surrounding rock of the retaining period roadway, wherein the retaining period re-injection reinforcement support scheme comprises a lagged working face grouting distance, grouting pressure, grouting amount and slurry proportioning parameters.

In a further preferred aspect of the present invention, in step S4, the secondary grouting is performed using a quick setting high-permeability flame-retardant polyurethane slurry or a polymer resin material.

Through the technical scheme, compared with the prior art, the invention has the following beneficial effects:

according to the method, the whole period integrated support of the tunneling period, the stoping period and the retaining period is carried out on the non-coal-pillar mining retaining roadway through the advanced grouting, the secondary tensioning and the retaining period, the secondary grouting and the tertiary tensioning and the retaining period in the tunneling period, the stoping period and the retaining period, so that the purposes of controlling the deformation of surrounding rocks and guaranteeing the section of the roadway are achieved.

Drawings

The invention will be further described with reference to the drawings and examples.

FIG. 1 is a schematic flow chart of a method for supporting a gob-side entry retaining anchor of the invention;

FIG. 2 is a schematic diagram of a full-cycle integrated support of "tunneling period+stoping period+entry retaining period" in an exemplary embodiment of the present invention;

FIG. 3 is a cross-sectional view of a support in an illustrative embodiment of the invention;

FIG. 4 is a top plan view of a roadway roof support in an exemplary embodiment of the invention;

fig. 5 is a side view of a roadway wall brace in an exemplary embodiment of the invention.

In the figure: 1. hollow high-strength grouting anchor cable; 2. hollow grouting anchor rod; 3. high-strength prestressed anchor rod.

Detailed Description

The invention will now be described in further detail with reference to the accompanying drawings. The drawings are simplified schematic representations which merely illustrate the basic structure of the invention and therefore show only the structures which are relevant to the invention.

In the description of the present invention, it should be understood that the terms "left", "right", "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the apparatus or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and "first", "second", etc. do not indicate the importance of the components, and thus are not to be construed as limiting the present invention. The specific dimensions adopted in the present embodiment are only for illustrating the technical solution, and do not limit the protection scope of the present invention.

Example 1

The embodiment provides a preferred implementation manner, as shown in fig. 1 to 5, of a method for supporting a non-coal pillar mining roadway anchor, according to the characteristic of long-time non-uniform deformation of surrounding rocks in a non-coal pillar mining roadway service period (a tunneling period, a stoping period and a roadway retaining period), the method is used for supporting the roadway in a full-period integrated mode through a hollow high-strength grouting anchor cable 1, a hollow grouting anchor rod 2 and a high-strength prestressed anchor rod 3, limiting early deformation of the surrounding rocks through anchor rod (cable) anchoring action in the tunneling period, improving the bearing capacity of the surrounding rocks of an advanced supporting pressure influence section through advanced grouting and secondary tensioning and pre-tensioning in the stoping period to control deformation, and improving the bearing capacity of the surrounding rocks of the roadway retaining section through secondary grouting and tertiary tensioning and pre-tensioning in the roadway retaining period to control deformation. The supporting method specifically comprises the following steps:

step S1, stoping a roadway tunneling period:

in the stoping roadway heading period, carrying out laboratory mechanical property test on surrounding rock samples obtained by drilling in the roadway to obtain roadway surrounding rock mechanical parameters, carrying out in-situ stress in-situ test to obtain roadway surrounding rock mechanical environment, and carrying out drilling peeping to obtain roadway surrounding rock deformation damage characteristics in the heading period; according to the mechanical parameters of the roadway surrounding rock, the stress environment and the deformation and damage characteristics of the roadway surrounding rock in the tunneling period, the anchoring and supporting scheme in the tunneling period, which adopts the hollow high-strength grouting anchor cable 1, the hollow grouting anchor rod 2 and the high-strength prestressed anchor rod 3 for supporting, is determined through theoretical calculation and numerical simulation.

In step S1 of this embodiment, a top plate, a bottom plate and a roadway wall of a roadway are peeped to obtain deformation and damage characteristics of surrounding rock of the roadway in a tunneling period, wherein the deformation and damage characteristics of the surrounding rock of the roadway in the tunneling period include crack development density, length, width and depth of the surrounding rock of the roadway; according to the mechanical parameters of the surrounding rock of the roadway, the stress environment and the deformation damage condition of the surrounding rock of the roadway in the tunneling period, the supporting strength is obtained through theoretical calculation, a tunneling period anchoring supporting scheme is designed, a full-period supporting numerical calculation model of the coal pillar-free mining roadway is built based on a strain softening constitutive model, the surrounding rock deformation and the plastic area distribution range of the tunneling roadway supported by the proposed tunneling period anchoring supporting scheme are analyzed, the tunneling period anchoring supporting scheme is optimized according to the numerical simulation result, and the optimized tunneling period anchoring supporting scheme comprises the diameter, the length, the pretightening force, the interval distance, the model and the number of anchoring agents and the model and the size of a tray.

S2, stoping roadway tunneling support period:

according to the supporting scheme determined in the step S1, the hollow high-strength grouting anchor cable 1, the hollow grouting anchor rod 2 and the high-strength prestressed anchor rod 3 are used for supporting the roadway, at the moment, the roadway is complete, grouting reinforcement is not needed, and the initial deformation of the roadway due to the tunneling can be effectively controlled only through the anchoring effect; and tensioning and pre-tightening the hollow high-strength grouting anchor cable 1, the hollow grouting anchor rod 2 and the high-strength pre-stress anchor rod 3 which are subjected to construction until the design pre-stress is achieved. The prestress design is a prestress value preset according to specific working conditions.

In the step S2 of the implementation scheme, the hollow grouting anchor rod 2 and the high-strength prestressed anchor rod 3 are constructed according to the row spacing of 800-1000 mm, and the hollow high-strength grouting anchor cable 1 is constructed according to the row spacing of 1600-2000 mm; in the section of the same roadway, the hollow grouting anchor rods 2 and the high-strength prestressed anchor rods 3 are constructed alternately; the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 are constructed at intervals, the hollow high-strength grouting anchor cable 1 is positioned between two rows of hollow grouting anchor rods 2, one row is used for constructing 1-3 hollow high-strength grouting anchor cables 1, and the other row is used for constructing 2-4 hollow grouting anchor rods 2; preferably, the design prestress of the hollow high-strength grouting anchor cable 1 is 100-200 kN, and the design prestress of the hollow grouting anchor rod 2 and the high-strength prestress anchor rod 3 is 50-100 kN.

Step S3, coal face stoping period:

According to the technical scheme of advanced anchor grouting support in the stoping period, grouting is carried out on the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 in the step S2 in a range of 30-80 m on an advanced working surface in the stoping roadway, grouting is carried out on the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 after grouting is finished, grouting is carried out on the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 and the high-strength prestressed anchor rod 3 after grouting is carried out, and secondary tensioning and pre-tightening are carried out on the grouting hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 3.

In step S3 of this embodiment, the specific step of monitoring the supporting pressure of the coal body is to drill a hole in the advanced support section of the stoping roadway, arrange the surrounding rock stress sensor in the surrounding rock of the roadway, actually measure the distribution characteristic of the advanced supporting pressure in the roadway during stoping, the distribution characteristic of the advanced supporting pressure includes the influence range, magnitude and stress concentration coefficient of the advanced supporting pressure;

Preferably, the grouting material in the embodiment adopts cement water glass slurry, and the water cement ratio of the cement slurry is: cement (mass ratio) =1:1; using liquid water glass with wave density 37, cement slurry: water glass (volume ratio) =1:0.1-0.2; and after grouting is completed, the slurry of the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 is discharged, and simultaneously, the grouting anchor cable with reduced pretightening force and the grouting anchor rod are tensioned and pretightened again.

S4, stoping roadway retaining period:

in the stoping roadway retaining period, drilling peeping and roadway deformation monitoring are carried out in the roadway to obtain roadway surrounding rock deformation damage characteristics in the roadway retaining period, and a roadway retaining period reinjection reinforcement supporting scheme is provided according to the roadway surrounding rock deformation damage characteristics in the roadway retaining period; according to the roadway re-grouting reinforcement support scheme in the entry retaining period, the working face is lagged by 2-4 cycles to press the step distance, secondary grouting is carried out on the top plates of the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 which are subjected to grouting in the step S3, and the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 which are subjected to secondary grouting and the high-strength prestressed anchor rod 3 are tensioned and pre-tensioned for three times.

In the step S4 of the embodiment, during the roadway retaining, the drilling peeping and roadway deformation monitoring are carried out in the roadway to obtain the deformation damage characteristics of the surrounding rock of the roadway in the roadway retaining period;

Preferably, the secondary grouting in the embodiment adopts quick setting high-permeability flame-retardant polyurethane slurry or high polymer resin material.

A specific example is now illustrated, in particular as follows:

the current working condition is that the section of the roadway of the coal pillar-free exploitation retaining roadway is 4800mm wide by 3000mm high, the roadway is tunneled along the roof of the coal seam, and the total length of the roadway is 1187m. The direct roof is 4m thick sandy mudstone and the basic roof is 5m thick fine sandstone. The working surface propulsion speed is 5m/d. The roadway needs to go through a driving period, a stoping period and a retaining period, and the roadway service period is long (the roadway needs to be serviced for about 2-3 years). The deformation damage of the surrounding rock intensively occurs in the stoping period and the entry retaining period, the surrounding rock is obviously damaged under the action of high-strength advanced supporting pressure in the stoping period, and the separation layer and shearing damage of the roof are obvious due to the covering rock of the goaf in the entry retaining period. The deformation separation layer of surrounding rock is caused by support failure in the early stage, so that the later stage deformation control difficulty is increased, and a full-period integrated support method is required to be provided according to the characteristic of long-time non-uniform deformation of a roadway.

According to the embodiment, aiming at the characteristic of non-uniform speed of a roadway in a long time, the full-period integrated support of a tunneling period, a stoping period and a retaining period is provided by adopting grouting anchor cables, and the method is different from the traditional tunneling anchor support or broken surrounding rock anchor support, and the method for retaining the roadway by coal pillar-free mining comprises the following steps of:

The method comprises the following steps of S1, constructing a hollow high-strength grouting anchor rope 1, a hollow grouting anchor rod 2 and a high-strength prestressed anchor rod 3 in a tunneling period to anchor and support a roadway, wherein the roadway is complete at the moment, grouting reinforcement is not needed, and initial deformation of the roadway tunneling can be effectively controlled only through an anchoring effect;

(a) Carrying out laboratory mechanical property tests on surrounding rock samples obtained by drilling the roadway to obtain mechanical parameters of the surrounding rock of the roadway, wherein the mechanical parameters comprise compressive strength, tensile strength, shear strength, cohesive force, internal friction angle, elastic modulus, poisson ratio and the like of the surrounding rock, so that the mechanical parameters of the rock are provided for theoretical calculation and numerical simulation in the design of an anchor support scheme in a tunneling period;

(b) The method comprises the steps of performing in-situ test of ground stress to obtain the mechanical environment of surrounding rock of a roadway, and performing test by a stress relief method or a hydraulic fracturing method to obtain the numerical values and directions of the maximum main stress, the middle main stress and the minimum main stress of the surrounding rock, so that design basis is provided for the arrangement of a hollow high-strength grouting anchor cable 1, a hollow grouting anchor rod 2 and a high-strength pre-stress anchor rod 3 of an anchor support scheme in a tunneling period;

(c) The method comprises the steps of (1) performing drilling peeping on a top plate, a bottom plate and a roadway side of a roadway to obtain deformation damage characteristics of roadway surrounding rock in a tunneling period, wherein the deformation damage characteristics comprise crack development density, length, width and depth of the roadway surrounding rock, and the development ranges of a broken area and a crack area of the roadway surrounding rock are determined, so that design basis is provided for the support lengths and densities of a hollow high-strength grouting anchor cable 1, a hollow grouting anchor rod 2 and a high-strength prestressed anchor rod 3 of an anchor support scheme in the tunneling period;

(d) Design theoretical calculation of anchor supporting scheme in tunneling period (calculated according to suspension theory)

(1) And (3) calculating the length of the anchor rod: l=kh+l ₁ +L ₂ ＝2×0.75+0.5+0.1＝2.10m。

Wherein: h=b/2f=5.66/(2×4) =0.71 m

Wherein L is the length of the anchor rod, m;

h-height of the falling arch, m;

k-safety factor, taking k=2;

L ₁ -anchoring the anchor rod to a depth of the stable rock stratum, typically 0.50m empirically;

L ₂ -the exposed length of the anchor rod in the roadway is 0.10m;

b, roadway digging width, wherein the maximum width is 5.66m;

f, the rock firmness coefficient is taken to be 4;

therefore, the anchor rod with the length of 2.40m is designed to meet the support requirement.

(2) And (3) calculating the diameter of the anchor rod:

wherein: q-anchoring force drawing test data, and taking tested data of 70kN;

R _t the design tensile strength of the anchor rod is 500MPa;

therefore, the design and the use of the anchor rod with the diameter of 20mm can meet the support requirement.

(3) Calculating the row spacing between the anchor rods:

α＝[Q/(KHγ)] ^1/2 ＝[70/(2×0.71×25)] ^1/2 ≈1.40m

wherein: alpha-row spacing between anchor rods;

q-designing anchoring force of the anchor rod, and taking 70 kN/root;

h, taking 0.71m of the height of the falling arch;

gamma-gravity density of suspended rock, 25kN/m ³ ；

K is a safety coefficient, and 2 is taken;

therefore, the row spacing between the anchor rods is 850 multiplied by 800mm, and the support requirement can be met.

(4) Anchor cable length calculation l=l ₁ +L ₂ +L ₃ ＝0.25+4+2＝6.25m

Wherein: l-length of anchor cable, m;

L ₁ -the exposed length of the anchor cable is 0.25m;

L ₂ -potential unstable rock level height, 4m;

L ₃ -anchor cable anchoring length, 2m;

therefore, the length of the designed anchor cable is 8300mm, and the support requirement can be met.

(5) Calculation of row spacing between anchor cables

According to the relation between the row spacing between anchor cables and the depth of anchor holes, the empirical formula is satisfied: l/s=8.05/1.6=5.03 > 2 formula: l-anchor cable hole depth, taking a minimum value of 8m;

s, the row spacing between anchor cables is 1.6m maximum;

therefore, the row spacing between designs is 1700 multiplied by 1600mm, and the support requirement can be met.

(e) According to the deformation and damage characteristics of roadway surrounding rock in the tunneling period, the depth of a roof breaking area is 0.65m and is smaller than the height H=0.71 m of a caving arch in theoretical calculation, the development height of a crack area is 3.65m and is smaller than the height L of a potential unstable rock layer ₂ =4m, so the theoretically calculated support parameters meet the support requirements of deformation and damage of the roadway surrounding rock in the tunneling period.

(f) According to the mechanical parameters and stress environment of the surrounding rock of the roadway, a full-period support numerical simulation model of the coal pillar-free mining roadway is established, the control effect of each scheme on roadway deformation under different support lengths and support densities is simulated, and finally proper support lengths and support densities are optimized.

(g) The theoretical calculation result, the deformation damage characteristic of the roadway surrounding rock in the tunneling period and the numerical simulation result are synthesized, and the tunneling period anchoring supporting scheme adopting the hollow high-strength grouting anchor cable 1, the hollow grouting anchor rod 2 and the high-strength prestressed anchor rod 3 for supporting is finally determined, wherein the tunneling period anchoring supporting scheme comprises the diameter, the length, the pretightening force, the interval row spacing, the model and the number of anchoring agents and the model and the size of a tray of the supporting body; .

The concrete parameters of the tunneling period anchoring and supporting scheme are as follows: the method comprises the steps of selecting a hollow grouting anchor rod 2 with the diameter of phi 25 multiplied by 2500mm, a high-strength prestressed anchor rod 3 with the diameter of phi 22 multiplied by 2500mm and a hollow high-strength grouting anchor rope 1 with the diameter of phi 22 multiplied by 8300mm, wherein the row spacing between the hollow grouting anchor rod 2 and the high-strength prestressed anchor rod 3 for roof construction is 850 multiplied by 800mm, the row spacing between the high-strength prestressed anchor rods 3 for wall construction is 840 multiplied by 800mm, and the row spacing between the hollow high-strength grouting anchor rope 1 for roof construction is 1700 multiplied by 1600mm. In the section of the same roadway, the hollow grouting anchor rods 2 and the high-strength prestressed anchor rods 3 are constructed alternately; the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rods 2 are constructed at intervals, and the hollow high-strength grouting anchor cable 1 is positioned between the two rows of hollow grouting anchor rods 2. One row of top plates is provided with 3 hollow high-strength grouting anchor cables 1, and the other row is provided with 2 hollow grouting anchor rods 2 and 4 high-strength prestressed anchor rods 3. And the top plate and the upper part of the roadway are paved with metal nets and steel belts to support surrounding rocks on the surface of the roadway, so that broken surrounding rocks are prevented from falling.

The breaking force of the hollow grouting anchor rod 2 is more than 100kN, the pretightening force is designed to be 50kN, and an anchor rod tray with the thickness of 100mm multiplied by 10mm is matched; the breaking force of the high-strength prestressed anchor rod 3 is more than 250kN, the pretightening force is designed to be 100kN, and an anchor rod tray with the thickness of 100 multiplied by 10mm is matched with the pretightening force; the breaking force of the hollow high-strength grouting anchor cable 1 is more than 400kN, the pretightening force is designed to be 200kN, the length of an anchoring section is 2000mm, a 300 multiplied by 16mm high-strength manganese steel drum-shaped tray is used in a matched mode, and the anchoring support parameters in the tunneling period are shown in figure 3.

S2, constructing a hollow high-strength grouting anchor rope 1, a hollow grouting anchor rod 2 and a high-strength pre-stress anchor rod 3 according to an anchor grouting tunneling supporting scheme, supporting a tunneling roadway, and tensioning and pre-tightening the constructed hollow high-strength grouting anchor rope 1, the hollow grouting anchor rod 2 and the high-strength pre-stress anchor rod 3 to design pre-stress; the design prestress of the hollow high-strength grouting anchor cable 1 is 200kN, the design prestress of the hollow grouting anchor rod 2 is 50kN, and the design prestress of the high-strength pre-stressing anchor rod 3 is 100kN.

And S3, under the action of advanced supporting pressure, deformation and crushing of a roadway are carried out, the integrity is reduced, meanwhile, a grouting anchor cable constructed in the tunneling period is loosened, and the anchor grouting support of the broken surrounding rock of the roadway in the stoping period can be realized through advanced grouting and secondary tensioning pre-tightening, so that the bearing capacity of the surrounding rock is improved through advanced grouting reinforcement on one hand, the anchoring effect is ensured through secondary tensioning, and the broken surrounding rock is prevented from being obviously deformed and damaged in the stoping period.

(a) In order to monitor the distribution condition of the supporting pressure of the coal body, drilling holes in an advanced supporting section of a stoping roadway, arranging a surrounding rock stress sensor in surrounding rock of the roadway, and actually measuring the distribution characteristic of the advanced supporting pressure in the roadway during stoping, wherein the distribution characteristic comprises the influence range, the size and the stress concentration coefficient of the advanced supporting pressure; monitoring to obtain an influence range of the advanced supporting pressure of 30m;

(b) Drilling and peeping the top plate and the roadway side of the stoping roadway to master the damage characteristics of the roadway surrounding rock in the stoping period, and peeping to obtain deformation damage conditions of the roadway surrounding rock at different distances of the advanced working face, wherein the deformation damage conditions comprise crack development density, length, width and depth of the roadway surrounding rock at different distances of the advanced working face; monitoring to obtain that roof surrounding rock is severely crushed within the range of 30m of the advanced working surface and is completely penetrated by the cracks; the roof surrounding rock within the range of more than 30m of the advanced working surface is complete, and partial cracks are formed in the roof;

(c) Setting a monitoring section at intervals of 50m by taking the position of the advanced working surface as a starting point, and monitoring deformation characteristics of the roadway in the stoping period, wherein the monitoring section comprises the approaching amount of the top and the bottom of the roadway and the approaching amount of the two sides at different distances of the advanced working surface; monitoring and finding that the deformation of the surrounding rock of the roadway is remarkable and the deformation speed is high, wherein the range of the deformation speed is 0-30 m of the advanced working surface;

(d) The influence range of the advanced supporting pressure, the surrounding rock destruction characteristics of the roadway in the stoping period and the roadway deformation monitoring result are synthesized, the surrounding rock is considered to bear larger stress within the range of 0-30 m of the advanced working surface, the surrounding rock is broken, and grouting reinforcement is carried out on the advanced working surface by more than 30m;

(e) On the basis of a full-period support numerical simulation model of a coal pillar-free mining roadway, an advanced anchor injection support numerical model in a stoping period is constructed, the numerical model is checked according to advanced support pressure distribution characteristics and stoping period roadway surrounding rock deformation damage characteristics, surrounding rock control effects of different advanced grouting construction parameters on a roadway advanced support section are analyzed through advanced anchor injection support numerical simulation, the surrounding rock control effects comprise roadway section convergence conditions and plastic region development conditions, advanced anchor injection support construction parameters are optimized and determined according to simulation results, and the advanced anchor injection support construction parameters comprise grouting pressure, grouting quantity and slurry proportioning parameters;

(f) The surrounding rock control effect and the slurry diffusion effect of the advanced anchor grouting support construction parameters are verified through on-site grouting tests, and the advanced anchor grouting support construction parameters are optimized according to on-site application conditions, so that the technical scheme of the advanced anchor grouting support is formed.

S4, grouting the grouting liquid of the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 which are constructed in the tunneling period in the second step is subjected to surrounding rock grouting reinforcement in the range of 30-80 m of the advanced working surface in the stoping roadway according to the advanced anchor grouting support technical scheme, grouting liquid of the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 is discharged after grouting is finished, and secondary tensioning and pre-tightening are carried out on the grouting hollow high-strength grouting anchor cable 1, the grouting hollow grouting anchor rod 2 and the high-strength pre-stressed anchor rod 3;

for example, the working surface is pushed to 300m, and grouting anchor cables and grouting anchor rods in the range of 330 m-380 m are subjected to grouting. The grouting material is made of superfine cement, and liquid water glass (sodium silicate) with Baume 37 is used as an additive of the grouting material. The cement paste has the following water-cement ratio: cement (mass ratio) =1:1, cement paste: water glass (volume ratio) =1:0.1-0.2, grouting pressure is 3-5 MPa, and grouting is stopped when the grouting quantity reaches 50 kg/hole after grouting to the top plate. After grouting is completed, the slurry of the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 is discharged, and secondary tensioning and pre-tightening are carried out on the hollow high-strength grouting anchor cable 1, the hollow grouting anchor rod 2 and the high-strength pre-stressing anchor rod 3 after grouting; and (3) repairing and beating the damaged positions of the grouting anchor cable and the grouting anchor rod again, tensioning and pre-tightening, and grouting.

And S5, during the roadway retention period, under the action of goaf overlying strata movement, surrounding rocks are subjected to shearing dislocation and separation layer, and the supporting effect of the surrounding rocks can be improved through secondary grouting and tertiary tensioning pre-tightening, so that the surrounding rocks are prevented from being obviously deformed and damaged during the roadway retention period. Drilling peeping and roadway deformation monitoring are carried out in the roadway to obtain roadway surrounding rock deformation damage characteristics in the roadway retaining period, and a re-injection reinforcement supporting scheme in the roadway retaining period is provided according to the roadway surrounding rock deformation damage characteristics in the roadway retaining period;

(a) In the step of drilling peeping, during a roadway retaining period, the roof and the roadway side of the roadway retaining section of the stoping roadway are drilled and peeped so as to grasp the damage characteristics of the roadway surrounding rock in the remaining period, and the peeping obtains the deformation damage conditions of the roadway surrounding rock at different distances of the lagging working surface, including the crack development density, the length, the width and the depth of the roadway surrounding rock at different distances of the lagging working surface;

(b) In the roadway deformation monitoring step, continuously monitoring deformation of a monitoring section arranged in a stoping period of a retaining period, and monitoring roadway deformation characteristics in the retaining period, wherein the monitoring section comprises a top-bottom plate approach amount and a two-side approach amount of a roadway at different distances of a lagged working surface;

(c) According to the deformation and damage characteristics of surrounding rock of the roadway in the roadway retaining period, determining and providing a supporting scheme for re-injection and reinforcement in the roadway retaining period, and providing a grouting distance of a lagged working face in the roadway retaining period of 30m;

And S6, carrying out secondary grouting on the top plates of the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 which are subjected to grouting in the step two within the range of 30-50 m of a lagged working surface according to a roadway retaining period re-grouting reinforcement support scheme. For example, the working surface is pushed to 300m, and grouting anchor cables and grouting anchor rods within the range of 250 m-270 m are subjected to secondary grouting. The grouting material is chemical slurry such as aqueous polyurethane, polymer resin material and the like, the grouting pressure is 3-5 MPa, and grouting is stopped when the grouting quantity reaches 50 kg/hole after grouting to the top plate. And the hollow high-strength grouting anchor cable 1 and the hollow grouting anchor rod 2 after secondary grouting and the high-strength prestressed anchor rod 3 are tensioned and pre-tensioned for three times. And (3) repairing and beating the damaged positions of the grouting anchor cable and the grouting anchor rod again, tensioning and pre-tightening, and grouting.

Comparing the application with the prior two support methods:

1. the existing supporting method aims at the tunneling supporting problem under the gob-side entry driving condition, and grouting is directly carried out in the tunneling period according to the crack development degree after the development degree of the surrounding rock crack is monitored through drilling peeping.

(1) Characteristics of the application object: the gob-side entry driving roadway only has a driving period and a stoping period, is abandoned after entering a goaf, has no roadway retention period, has a shorter service period, does not relate to the roadway retention period support problem, and only needs to consider the safety problem of ensuring the stoping period.

(2) The core thought of support: the supporting method considers that grouting reinforcement is carried out on the roadway in the tunneling period, and advanced supporting is not needed in the subsequent stoping period. This is because:

on one hand, the application object of the supporting method is a gob-side entry driving roadway adjacent to a goaf, the roadway surrounding rock is broken and cracks develop under the influence of mining disturbance of an adjacent working face and the mining disturbance of the gob-side entry driving roadway, if grouting reinforcement is not carried out immediately, deformation occurs immediately after the roadway is driven, and the roadway is difficult to support to a mining period;

on the other hand, after the grouting is carried out on the tunneling support, the tunnel is ensured not to be deformed obviously, and the grouting can be served to the stoping period. Although the roadway in the stoping period can be obviously deformed, the roadway is not required to be controlled to deform because the gob-side entry driving roadway is not subjected to the roadway retaining service, and the roadway is ensured not to collapse.

The supporting method is not suitable for the working condition of the application, and is specifically as follows:

firstly, the working condition of the application is the problem of full-period support of the tunneling-stoping-retaining roadway of the stoping roadway of solid coal on both sides, the surrounding rock condition in the tunneling period is better, grouting reinforcement is not needed, the cracks are fewer, at the moment, grouting can not be carried out ideally, and the grouting reinforcement effect is not realized;

Secondly, according to the thought of the supporting method, after one-time grouting reinforcement is carried out in a tunneling period, if reinforcement support is not carried out in a stoping period, the roadway is obviously damaged under the action of advanced supporting pressure in the stoping period, and the irreversible and difficult-to-maintain roadway is obviously deformed and damaged to cause incapability of retaining the roadway;

finally, the support method relates to grouting of the coal pillar upper, and the application discloses a coal pillar-free roadway with a retaining roadway and no coal pillar.

The application has the advantages compared with the supporting method that:

(1) The supporting method does not describe a supporting parameter determining method, but the application determines a tunneling period anchoring supporting scheme by theoretical and numerical simulation according to surrounding rock mechanical parameters, site stress environment and surrounding rock damage conditions;

(2) The support method is a method for judging whether grouting is performed in a tunneling period by monitoring the development degree of surrounding rock cracks, and the judgment index is the crack width, so that grouting reinforcement of partial grouting anchor rods and grouting anchor cables is selected according to the surrounding rock crushing degree.

The grouting judgment method is divided into a recovery period and a tunneling period, and aims to determine reasonable advanced grouting distance and delay grouting distance, fully grouting anchor rods and grouting anchor cables, and evaluating indexes of crushing degree are more detailed, wherein the indexes comprise crack development density, length, width and depth. Simultaneously, numerical simulation and grouting experiments are firstly carried out to reduce grouting cost and ensure supporting effect:

(1) Grouting in the stoping period is to monitor the supporting pressure of the coal body on site in the roadway, monitor the deformation of the roadway by peeping the drilling hole, and firstly obtain the distribution characteristic of the supporting pressure in advance and the deformation and damage characteristic of surrounding rock of the roadway in the stoping period; then according to the advanced support pressure distribution characteristics and the deformation and damage characteristics of the roadway surrounding rock in the recovery period, the advanced support pressure distribution characteristics comprise crack development density, length, width and depth of the roadway surrounding rock at different distances of the advanced working surface; through advanced anchor grouting support numerical simulation and grouting test in the stoping period, a technical scheme of advanced anchor grouting support in the stoping period is provided, and the technical scheme of advanced anchor grouting support in the stoping period comprises grouting distance, grouting amount and the like;

(2) during the entry retaining period, performing drilling peeping and monitoring the deformation of the roadway to obtain deformation damage characteristics of surrounding rocks of the roadway during the entry retaining period, wherein the deformation damage characteristics comprise crack development density, length, width and depth of the surrounding rocks of the roadway at different distances of a lagged working surface; and providing a retaining period re-injection reinforcement support scheme according to the deformation and damage characteristics of the surrounding rock of the retaining period roadway, wherein the retaining period re-injection reinforcement support scheme comprises a lagged working face grouting distance, grouting pressure, grouting amount and slurry proportioning parameters.

2. The existing other support method aims at the problems of tunneling support and stoping support of a stoping roadway, grouting anchor cables are constructed during tunneling support, grouting is carried out to be performed in a stoping period leading section.

(1) Characteristics of the application object: the stoping roadway in the supporting method only has a tunneling period and a stoping period, the problems of roadway retention and roadway retention period supporting are not mentioned, and the roadway retention is not considered. The service period of the roadway is short, and only the problem of ensuring the safety of the recovery period is considered.

(2) The core thought of support: the support method provides that grouting anchor cable support is adopted at one time when a roadway with better geological conditions of a coal mine is tunneled, and grouting reinforcement support is carried out on a top plate advanced support section during stoping.

The full life cycle support of this support method is not applicable to the working conditions of the present application, and is specifically as follows:

firstly, the working condition of the application is the problem of full-period support of the tunneling-stoping-retaining roadway of the stoping roadway of the solid coal on both sides, and the full-life period support of the support method only comprises the tunneling period and the stoping period, and the working condition of the support method is the stoping roadway without retaining roadway;

then, according to the thought of the supporting method, after grouting reinforcement of the roadway in the stoping period, the safety of the stoping roadway in the stoping period can be ensured, and the roadway is not obviously damaged to a certain extent under the action of the advanced supporting pressure. The working condition of the application needs to consider the support of the retaining period, enters the retaining period, is influenced by the rock covering movement of the goaf, and is damaged by the advanced mining action, if grouting reinforcement is not adopted, the long-term retaining effect is difficult to ensure, and the retaining roadway cannot continue to serve the next working face.

The application has the advantages compared with the supporting method that:

(1) The supporting method only adopts grouting anchor cables for supporting, has the advantages of small supporting density, small workload, low cost and the like when being applied to roadways with good coal mine geological conditions, but is not applicable to roadways with broken surrounding rocks, and has the problems of insufficient supporting density, low integrity of supporting-surrounding rock systems, insufficient supporting strength of surface surrounding rock protecting surfaces and the like. According to the application, the grouting anchor rod and the high-strength anchor rod are used for reinforcing the broken surrounding rock of the shallow part to form the bearing structure in the shallow part, and then the bearing structure in the shallow part and the outer bearing structure of the stable surrounding rock in the deep part are anchored together through the grouting anchor rope to form the integral inner and outer bearing structure.

(2) In the support method, the support strength of the stoping roadway is determined according to the surrounding rock mechanical parameters and the loose ring range parameters, then the stress distribution conditions of tunneling and stoping are obtained through numerical simulation, and the support strength and grouting anchor cable construction parameters are calculated theoretically. According to the surrounding rock mechanical parameters, the on-site actual measurement stress environment and the surrounding rock damage condition, a preliminary scheme is obtained through theoretical calculation, effects of different supporting schemes are simulated numerically, and finally an anchor supporting scheme in a tunneling period is determined; on one hand, the stress environment actually measured on site is important, and the design of supporting parameters and the supporting effect are affected; on the other hand, theoretical calculation can only calculate density and strength, and numerical simulation of the supporting effect of different supporting schemes can better determine proper arrangement schemes.

(3) The concrete advanced working face grouting position and the concrete advanced working face grouting determination method are not provided in the support method, concrete surrounding rock damage degree evaluation indexes are not provided, and only: and grouting the grouting anchor cable of the advanced support section of the roadway during stoping after stoping, so as to complete support. The application provides a concrete grouting position judging method in the recovery period and the tunneling period respectively, and provides evaluation indexes of the surrounding rock breaking degree, including crack development density, length, width and depth. Simultaneously, numerical simulation and grouting experiments are performed to comprehensively determine grouting positions so as to reduce grouting cost and ensure supporting effect:

(1) grouting in the stoping period is to monitor the supporting pressure of the coal body on site in the roadway, monitor the deformation of the roadway by peeping the drilling hole, and firstly obtain the distribution characteristic of the supporting pressure in advance and the deformation and damage characteristic of surrounding rock of the roadway in the stoping period; then according to the advanced support pressure distribution characteristics and the deformation and damage characteristics of the roadway surrounding rock in the recovery period, the advanced support pressure distribution characteristics comprise crack development density, length, width and depth of the roadway surrounding rock at different distances of the advanced working surface; according to the numerical simulation and grouting test of the advanced anchor grouting support in the stoping period, a technical scheme of the advanced anchor grouting support in the stoping period, namely grouting distance and grouting quantity, is provided;

It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

The meaning of "and/or" in the present application means that each exists alone or both exist.

"connected" as used herein means either a direct connection between components or an indirect connection between components via other components.

With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.

Claims

1. The anchor injection supporting method for the coal pillar-free mining roadway retaining is characterized by comprising the following steps of:

step S1, stoping a roadway tunneling period:

s2, stoping roadway tunneling support period:

constructing a hollow high-strength grouting anchor cable (1), a hollow grouting anchor rod (2) and a high-strength pre-stressing anchor rod (3) according to the supporting scheme determined in the step S1, supporting a roadway, and tensioning and pre-tightening the constructed hollow high-strength grouting anchor cable (1), the hollow grouting anchor rod (2) and the high-strength pre-stressing anchor rod (3) to design pre-stressing;

Step S3, coal face stoping period:

according to the technical scheme of advanced anchor grouting support in the stoping period, grouting is carried out on the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rod (2) in the step S2 within the range of 30-80 m on an advanced working surface in the stoping roadway, grouting is carried out on the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rod (2) after grouting is finished, grouting liquid of the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rod (2) is discharged, and secondary tensioning and pre-tightening are carried out on the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rod (2) and the high-strength pre-stress anchor rod (3) after grouting;

s4, stoping roadway retaining period:

According to the roadway re-grouting reinforcement supporting scheme in the roadway retaining period, the working face is lagged by 2-4 cycles to press the step distance, secondary grouting is conducted on the top plates of the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rod (2) which are subjected to grouting in the step S3, and the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rod (2) after secondary grouting and the high-strength prestressed anchor rod (3) are subjected to three tensioning pre-tightening.

2. The method for supporting the anchor in the roadway of the coal pillar-free mining and is characterized by comprising the following steps of: in the step S1, a top plate, a bottom plate and a roadway side of a roadway are subjected to drilling peeping, and roadway surrounding rock deformation damage characteristics in a tunneling period are obtained, wherein the roadway surrounding rock deformation damage characteristics in the tunneling period comprise crack development density, length, width and depth of roadway surrounding rock; according to the mechanical parameters of the surrounding rock of the roadway, the stress environment and the deformation damage condition of the surrounding rock of the roadway in the tunneling period, the supporting strength is obtained through theoretical calculation, a tunneling period anchoring supporting scheme is designed, a full-period supporting numerical calculation model of the coal pillar-free mining roadway is built based on a strain softening constitutive model, the surrounding rock deformation and the plastic area distribution range of the tunneling roadway supported by the proposed tunneling period anchoring supporting scheme are analyzed, the tunneling period anchoring supporting scheme is optimized according to the numerical simulation result, and the optimized tunneling period anchoring supporting scheme comprises the diameter, the length, the pretightening force, the interval distance, the model and the number of anchoring agents and the model and the size of a tray.

3. The method for supporting the anchor in the roadway of the coal pillar-free mining and is characterized by comprising the following steps of: in the step S2, the hollow grouting anchor rod (2) and the high-strength prestressed anchor rod (3) are constructed according to the row spacing of 800-1000 mm, and the hollow high-strength grouting anchor cable (1) is constructed according to the row spacing of 1600-2000 mm; in the section of the same roadway, the hollow grouting anchor rods (2) and the high-strength prestressed anchor rods (3) are constructed alternately; the hollow high-strength grouting anchor cable (1) and the hollow grouting anchor rods (2) are constructed at intervals, the hollow high-strength grouting anchor cable (1) is positioned between two rows of hollow grouting anchor rods (2), one row of 1-3 hollow high-strength grouting anchor cables (1) is constructed, and the other row of 2-4 hollow grouting anchor rods (2) is constructed.

4. The method for supporting the anchor in the roadway of the coal pillar-free mining and is characterized by comprising the following steps of: in the step S3, the coal body supporting pressure monitoring specifically comprises the steps of drilling holes in an advanced supporting section of a stoping roadway, arranging surrounding rock stress sensors in surrounding rock of the roadway, and actually measuring the advanced supporting pressure distribution characteristics in the roadway during stoping, wherein the advanced supporting pressure distribution characteristics comprise the influence range, the size and the stress concentration coefficient of the advanced supporting pressure;

5. The method for supporting the anchor in the roadway of the coal pillar-free mining and is characterized by comprising the following steps of: in the step S3, cement water glass slurry is adopted as grouting material, and the cement slurry has the following water-cement ratio: cement (mass ratio) =1:1; using liquid water glass with wave density 37, cement slurry: water glass (volume ratio) =1:0.1-0.2.

6. The method for supporting the anchor in the roadway of the coal pillar-free mining and is characterized by comprising the following steps of: in the step S4, during the roadway retaining, the drilling peeping and roadway deformation monitoring are carried out in the roadway to obtain the deformation damage characteristics of the surrounding rock of the roadway in the roadway retaining period;

7. The method for supporting the anchor in the roadway of the coal pillar-free mining and is characterized by comprising the following steps of: in the step S4, the secondary grouting adopts quick setting high-permeability flame-retardant polyurethane slurry or high polymer resin material.