CN116291483A - Advanced pretreatment method for ground of poor geological stratum of deep-buried long large tunnel - Google Patents

Abstract

The invention discloses a method for advanced pretreatment of the ground of a poor geological stratum of a deep-buried long large tunnel, which comprises the following steps: step A, determining the surface advanced grouting range; step B, arranging surface advanced grouting holes: step C, arranging pilot test holes for surface advanced grouting: selecting a drilling hole as a pilot test hole, and performing ground L-shaped directional drilling advanced exploration and drilling grouting test; step D, selecting earth surface advanced grouting materials and calculating grouting quantity; e, grouting the ground; according to the method, the surface pre-grouting treatment is carried out on the main tunnel section of the tunnel with the poor geological section, so that risks faced by tunnel construction are reduced, and the construction efficiency and construction period guarantee measures are improved; the tunnel is treated in advance through the surface pre-grouting, so that the construction period occupied by grouting treatment in the tunnel is reduced, the restriction of various adverse factors on the construction period is reduced, and the guarantee rate of the construction period can be improved.

Description

Advanced pretreatment method for ground of poor geological stratum of deep-buried long large tunnel

Technical Field

The invention relates to the technical field of tunnel construction. In particular to a ground advanced pretreatment method for poor geological strata of a deep-buried long tunnel.

Background

When tunnel construction is carried out under poor geological conditions, due to complex topographic and geological conditions, a plurality of geological problems can be encountered in tunnel engineering, and especially for an ultra-long tunnel which passes through a plurality of regional and full new-generation movable large breaks, the main technical difficulties of the tunnel engineering are as follows:

1) The structural movement is active, the fracture development in the region and the extremely complex engineering geology hydrogeological conditions caused by the geomorphic evolution process are generated;

2) The deep-buried long large tunnel has the characteristics of large buried depth, large crossing of multiple regional and full new generation activity fracture and large fracture, so that the regional structure background and geological conditions of the tunnel are complex, and the tunnel has the characteristics of various lithology and wide distribution of karst hydrogeological units;

3) The underground water is rich, the external water pressure is high, the crushed rock is a relative water-resisting layer, the pourability is poor, but the seepage resistance damage capability is low, and the conventional grouting mode and the drainage decompression effect are poor; drainage decompression, seepage stabilization and groundwater environment protection coordination control are difficult under high groundwater environment;

4) The tunnel passes through a plurality of regional wide fractures, the length of the soft rock tunnel section which is easy to generate serious-extremely serious extrusion deformation has a certain duty ratio, and especially in high groundwater areas, the seepage effect of groundwater can further reduce the stability of broken weak rock mass, the risk of collapse instability of surrounding rock is high, and the construction speed is seriously influenced.

According to domestic and foreign engineering experience, advanced grouting treatment is the most commonly used technology for tunnel crossing poor geological tunnel sections. The grouting method can be divided into two schemes of in-hole advanced grouting and surface advanced grouting treatment by combining the application of modern construction equipment. The conventional in-hole grouting treatment scheme is relatively flexible, grouting can be performed at a smaller hole pitch by adjusting the hole spacing, the quality is relatively easy to ensure, and meanwhile, the arrangement and grouting process of the curing grouting holes can be adjusted in real time according to the conditions of the rock body in the hole which are disclosed by the section-by-section excavation, so that the construction is ensured to be carried out smoothly; but the main disadvantages are that the advanced grouting in the hole directly occupies the straight construction period of the face, the number of holes drilled per cycle is large, the drilling engineering amount is large, and the construction cost is high. The advanced earth surface grouting treatment scheme does not occupy the main line construction period basically, can finish grouting before main hole tunneling, has relatively short construction period, but for a deep buried long large tunnel penetrating through a brand new movable fracture zone, belongs to a special poor geological problem concentrated hole section, is broken in rock mass and strong in water permeability, and the surface carbonate rock in the tunnel zone is widely distributed, belongs to a strong karst stratum, is rich in underground water type along the line, has high underground water level, and cannot well treat the hole section reinforcement under the poor geological condition in the conventional advanced earth surface grouting treatment mode, so that improvement and optimization are needed.

Disclosure of Invention

Therefore, the technical problem to be solved by the invention is to provide the advanced pre-treatment method for the ground of the poor geological stratum of the deep-buried long large tunnel, which has high reinforcement success rate and small comprehensive risk.

In order to solve the technical problems, the invention provides the following technical scheme:

a ground advanced pretreatment method for poor geological strata of a deep-buried long large tunnel comprises the following steps:

step A, determining the surface advanced grouting range, namely performing ground exploration along the line of a fracture zone on a main tunnel planning route of a tunnel, and determining advanced grouting tunnel sections, grouting section division of the grouting sections and positions near the surface of the axis of the main tunnel, wherein the positions are provided with drilling site construction conditions;

step B, arranging surface advanced grouting holes: determining the arrangement coordinates of grouting drilling hole site planes of grouting sections of each grouting hole section, arranging ground drilling sites, determining the thickness of a grouting reinforcement ring, and determining the arrangement of grouting hole sections;

step C, arranging pilot test holes for surface advanced grouting: selecting a drilling hole as a pilot test hole, and performing ground L-shaped directional drilling advanced exploration and drilling grouting test;

step D, selecting earth surface advanced grouting materials and calculating grouting quantity;

e, grouting the ground: the vertical straight hole section and the deflecting section both adopt sleeve pipe retaining walls, the horizontal grouting section firstly adopts a sectional advancing grouting mode to carry out water plugging grouting of a bare hole, then the flowtube is lowered, and the high-pressure quantitative mode is adopted to carry out compaction and splitting grouting of surrounding rocks around a tunnel, so that an anti-seepage consolidation curtain ring is formed.

Furthermore, the step E also comprises grouting effect inspection, and the advanced grouting effect of the earth surface is judged by combining drilling grouting process parameter analysis, pressurized water test data comparison, geophysical prospecting test and pressurized water test detection.

Furthermore, according to the characteristics that the gradient of the tunnel is small, the tunnel passes through the poor geological stratum in a nearly horizontal state, the excavation section is round or nearly round, the grouting sections of the grouting holes are nearly horizontal in the same direction as the trend of the tunnel, and the grouting holes are arranged outside the excavation diameter of the main tunnel of the tunnel and are uniformly distributed along the circumference.

Further, the length of a tunnel penetrating through a poor geological stratum exceeds 1000m, the tunnel is divided into a plurality of grouting sections, a typical drilling hole is taken as a pilot test hole, and grouting parameters and a construction range are dynamically adjusted according to the test condition of the test hole and the progress of each working face.

Further, the length of a tunnel penetrating through a poor geological stratum is 2000-2500 m, the tunnel is divided into four grouting sections, typical drilling holes of each grouting section are taken as pilot test holes, and grouting parameters and construction range are dynamically adjusted according to the test conditions of the test holes and the progress of each working face.

Further, the drilling length of the vertical straight hole section of each grouting drilling hole is determined according to the depth of the surface soil section, the drilling length of the deflecting section is determined according to the buried depth and the target front distance, and the drilling length of the horizontal grouting section is 400-800m.

Further, the vertical straight hole section is provided with a steel sleeve with the diameter of phi 245+/-0.5 mm multiplied by 9+/-0.06 mm according to the drilling diameter, the deflecting section is provided with a steel sleeve with the diameter of phi 178+/-0.5 mm multiplied by 8+/-0.05 mm according to the drilling diameter, and the standard of the flower pipe is phi 133+/-0.5 mm multiplied by 6+/-0.05 mm; the sleeve pipe of the deflecting section is directly down to the surface of the orifice, and is overlapped with the straight hole section by 20m at a part distance, and the flower pipe section is overlapped with the deflecting section.

Further, in the horizontal grouting section, each small section grouting section in the sectional forward grouting adopted at first has the length of 30-60 m, the grouting material adopts modified single-liquid cement slurry, and comprehensive clay cement slurry, modified urea resin chemical slurry or modified silicate slurry is selected for assistance according to the field requirement; the grouting end pressure is 3MPa-6MPa, when the grouting pump quantity is reduced to 50L/min-60L/min and the grouting pressure reaches the end pressure value, the grouting operation of the hole section can be ended after the grouting pressure is stabilized by 20 min-30 min; the length of the grouting section in the compaction splitting grouting stage after the flowtube is put down is reduced to 10m-30m, the grouting end pressure is dynamically adjusted according to the stratum crushing condition and the grouting amount, and when the grouting pump amount is reduced to 50L/min-60L/min and the grouting pressure reaches a final pressure value, the grouting operation of the hole section can be ended after the grouting pressure is stabilized by 20 min-30 min.

Further, the modified single-fluid cement slurry takes cement and water as main raw materials, the water-cement ratio is (1:1) - (0.8:1), and one or more of sodium chloride, triethanolamine, silica fume, water glass, bentonite and polymer materials are added according to the actual requirements of the site to modify the slurry;

wherein the addition of sodium chloride is 3-5 wt% of the weight of the cement, the addition of triethanolamine is 0.3-0.5 wt% of the weight of the cement, the addition of micro silicon powder is 5-20 wt% of the weight of the cement, the addition of water glass is 5-50 wt% of the weight of the cement, the addition of bentonite is 10-80 wt% of the weight of the cement, and the addition of polymer is 1-6 wt% of the weight of the cement;

the modified urea-formaldehyde resin chemical slurry consists of the following raw materials in parts by volume: 50 to 60 parts of urea-formaldehyde resin, 10 to 20 parts of oxalic acid solution, 5 to 10 parts of ammonium chloride solution, 1 to 3 parts of polyacrylamide solution, 1 to 5 parts of sodium carboxymethyl cellulose solution, 1 to 3 parts of magnesium powder solution, 10 to 20 parts of water and 5 to 10 parts of polyacrylic emulsion;

the modified silicate slurry consists of the following raw materials in parts by volume: 50 to 70 parts of sodium silicate solution, 5 to 15 parts of ethylene glycol diacetate, 3 to 5 parts of butyrolactone, 3 to 5 parts of ethyl acetate, 1 to 3 parts of sodium polyphosphate solution, 1 to 3 parts of oxalic acid solution, 1 to 5 parts of formamide solution and 10 to 30 parts of water.

Further, the main tunnel is a circular section, the diameter of the net section is 5m-10.0m, the burial depth is 400m-1000m, and the thickness of the grouting reinforcement ring is 6m-12m.

Further, the main tunnel is of a circular section, the diameter of the net section is 8.3m-10.0m, the burial depth is 500m-600m, and the thickness of the grouting reinforcement ring is 9.8m-10.0m.

Furthermore, each drilling site is provided with an even number of grouting drilling holes and a plurality of drilling machines, each drilling machine is used for constructing 2 spatially adjacent grouting holes, the two-step construction is carried out, and the construction working procedures of each grouting hole are consistent; the construction process of each grouting hole comprises the following steps:

and (3) construction: constructing a drill hole with the diameter of 311.1mm, and lowering a sleeve with the diameter of 244.5mm and the diameter of 8.94mm to fix the pipe;

and (3) two-step construction: continuously downwards constructing a drill hole with the diameter of 215.9mm in the first casing pipe, and downwards placing a casing pipe with the diameter of 177.8mm and a fixed pipe with the diameter of 8.05 mm;

horizontal grouting section construction: drilling a section and grouting a section by adopting sectional forward type bare hole grouting, and continuously drilling the next section and grouting after grouting pressure and flow meet the technical requirements until grouting of all grouting sections is finished;

and (3) lowering a three-flowering pipe: after the grouting construction of the bare hole grouting section is completed, a flower pipe is lowered in the drilled hole, the hole bottom is up to the hole opening, and the pipe is fixed;

grouting a flower pipe: the method is consistent with the bare hole grouting process, and then the section high-pressure splitting and compaction grouting are carried out on the area of which the bare hole grouting is finished through the flowtube;

And (3) hole sealing: and sealing the whole holes by using single-liquid cement slurry with the water-cement ratio of 0.6:1.

The technical scheme of the invention has the following beneficial technical effects:

according to the method, the surface pre-grouting treatment is carried out on the main tunnel section of the tunnel with the poor geological section, so that risks faced by main tunnel construction are reduced, and the construction efficiency and construction period guarantee measures are improved; the main hole is treated in advance through the surface pre-grouting, so that the construction period occupied by the grouting treatment in the main hole is reduced, the restriction of various adverse factors on the construction period is reduced, and the guarantee rate of the construction period can be improved;

the drilling track of the grouting section is always positioned in a target stratum through the ground L-shaped directional drilling advanced grouting, high-pressure water shutoff and splitting grouting are adopted to perform high-pressure grouting on the hole section penetrating through the geological fracture zone, so that the fracture water guide channel of the aquifer is effectively plugged, the water permeability of the aquifer is reduced, the strength of surrounding rock is improved, and the water surge cement burst and the water environment influence risk are reduced when the fracture zone, the syncline core and other water collecting structures are formed; an effective curtain is formed in a certain area range around the tunnel to resist high-head pressure-bearing water of the water-rich stratum, so that the risks of large-scale water gushing and mud bursting possibly existing in tunnel excavation are reduced, and favorable conditions are created for safe and smooth construction of the main tunnel.

Drawings

FIG. 1 is a schematic diagram of advanced grouting of a ground "L" directional drill hole;

FIG. 2 is a sectional layout range diagram of surface advanced grouting according to an embodiment of the invention;

FIG. 3 is a cross-sectional layout of a surface advanced grouting hole and a grouting intersection chart of an embodiment of the invention;

FIG. 4 shows a construction procedure of surface advanced grouting drilling grouting according to an embodiment of the invention;

fig. 5 is a schematic view of a ground grouting according to an embodiment of the present invention.

The reference numerals in the drawings are as follows: 1-a control cabinet; 2-a cement tank; 3-screw conveyor; 4-a hopper; 5-a primary stirring pool; 6-a secondary stirring tank; 7-a slurry conveying pipe; 8-grouting pump; 9-a drilling machine; 10-grouting holes; 11-a sleeve; 12-an injected formation; 13-tunnel main hole lining structure.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

In the following, a description will be given of a part of a tunnel section in a deep-buried long large tunnel XX mountain tunnel to be penetrated by a certain river-sisal fracture zone (mainly broken rock, breccia and broken rock, the original rock is mainly basalt, a small amount of north government office in feudal China groups of limestone), a lime kiln fracture zone (mainly broken rock, breccia and broken rock are formed), the original rock is a mountain basalt, a small amount of north government office in feudal China groups of limestone, a part of the tunnel section in the deep-buried long large tunnel XX mountain tunnel is exemplified, the river-sisal fracture zone is a brand new movable fracture large fracture, the basic earthquake intensity is VIII degree, the tunnel lithology is various, the karst hydrogeological units are widely distributed, and in the embodiment, pile numbers dli24+066-25+686 sections (located in the river fracture zone), pile numbers dli27+875-28+449 sections (lime kiln fracture zone), the lengths of 1620m and 574m are respectively, and the total length of the through bad geological section is about 2200m.

As shown in fig. 1 to 5, the advanced pre-treatment method for the ground of the poor geological stratum of the deep-buried long large tunnel comprises the following steps:

step A, determining the surface advanced grouting range, namely performing ground exploration along the line of a fracture zone on a main tunnel planning route of a tunnel, and determining advanced grouting tunnel sections, grouting section division of the grouting sections and positions near the surface of the axis of the main tunnel, wherein the positions are provided with drilling site construction conditions;

step B, arranging surface advanced grouting holes: determining planned arrangement coordinates of grouting drilling hole site planes of grouting sections of each grouting hole section, arranging ground drilling sites, determining the thickness of a grouting reinforcement ring, and determining the arrangement of grouting hole sections;

step C, arranging pilot test holes for surface advanced grouting: selecting a drilling hole as a pilot test hole, and performing ground L-shaped directional drilling advanced exploration and drilling grouting test;

step D, selecting earth surface advanced grouting materials and calculating grouting quantity;

e, grouting the ground: the vertical straight hole section and the deflecting section both adopt sleeve pipe retaining walls, the horizontal grouting section firstly adopts a sectional advancing grouting mode to carry out water plugging grouting of a bare hole, then the flowtube is lowered, and the high-pressure quantitative mode is adopted to carry out compaction and splitting grouting of surrounding rocks around a tunnel, so that an anti-seepage consolidation curtain ring is formed.

According to the invention, the purpose of water shutoff is achieved through ground advanced grouting, the water guide channel of underground water to the tunnel is plugged, the water inflow in the tunneling process of the tunnel is reduced, so that the construction safety and the environment safety are ensured, and favorable conditions are created for safe and smooth construction of the tunnel; meanwhile, the purpose of surrounding rock reinforcement is achieved, grouting slurry is injected into surrounding rock, so that a reinforcing ring is formed on the rock mass around the hole, and the overall strength and stability of the rock mass are improved.

Further, before ground grouting, evaluating anti-seepage grouting measures of the hole section; specifically, a hydrogeologic structure model with the depth of a tunnel region of about 1600m and the bottom plate Gao Chengyao m is established by using GMS7.1, the water inflow during tunnel excavation is analyzed, the underground water level variation possibly caused by tunnel drainage is quantitatively calculated, and the environmental influence possibly caused by water level drop is evaluated; and predicting the water inflow of tunnel excavation under different working conditions through the established groundwater seepage model, wherein the predicted result of the water inflow under each working condition is shown in the following table:

in the table above, condition one: natural bare hole; working condition II: partial grouting (water inflow q for bare hole)>3m ³ Performing common grouting on the m.d hole section, wherein the grouting standard is 10-5 cm/s; and (3) working condition III: secondary grouting (water inflow q after common grouting) >3-5m ³ The/m.d hole section is changed into ground cement grouting with the grouting standard of 5 multiplied by 10 < -6 > cm/s; water inflow q after common grouting>5m ³ The/m.d hole section is changed into chemical grouting, and the grouting standard is 1 multiplied by 10 < -6 > cm/s; as shown in the table, after the anti-seepage grouting measure is adopted for the whole hole, the water inflow quantity at main structural parts such as the break of Lijiang-Jianchuan and the broken belt of the lime kiln is more than 10m from q ³ Reduced/(d.times.m) to q < 2.33m ³ And (d.times.m), the water inflow is already significantly smaller than in the case of no grouting, and therefore, it is recommended to take anti-seepage grouting measures for the present hole section.

Specifically, according to the characteristics that the gradient of the tunnel is small, the tunnel passes through poor geological strata in a nearly horizontal state, and the excavation section is round or nearly round, grouting sections of grouting holes are nearly horizontal, and the grouting holes are arranged outside the excavation diameter of the main tunnel and are uniformly distributed along the circumference; in the step A, the investigation result shows that the Lijiang-Camellia fracture zone, the lime kiln fracture zone and the rock body in the zone affected by the Lijiang-Camellia fracture zone are broken, the main fracture zone and the mud page lithology in the zone affected by the lime kiln fracture zone are soft, the basalt water permeability is strong, the problems and risks of water gushing and mud bursting, large deformation of soft rock and high water outside exist, and the risk of environmental influence is caused by communicating with the ground surface Ru Na river; the maximum external water pressure of the Lijiang-Camellia fracture zone (pile number DLI24+066-25+686 section) reaches 2.18MPa, and the maximum external water pressure of the lime kiln fracture zone (DLI27+875-28+449 section) reaches 2.25MPa; the section of the earth surface advanced grouting hole is a pile number DLI24+066-25+686 section and a DLI27+875-28+449 section; the position of the earth surface grouting drilling site which can be used for the grouting hole section is surveyed, and the conditions of temporary land characterization and earth surface construction are provided near the axial pile numbers DLI23+808, DLI25+223, DLI25+862 and DLI27+465 of the tunnel; comprehensively considering factors such as the length of a poor geological hole section, the earth surface position, the deflection range of an L-shaped directional drilling hole on the ground, the construction period balance and the like, dividing the earth surface advanced grouting into four sections, and determining the length of a horizontal grouting section according to the drilling depth, the geological condition, the earth surface construction condition and the mutual overlap length (considered according to 30 m); pile number DLI24+066-25+686 (through Lijiang-Camellia fracture zone hole section) is carried out by adopting 3-section surface advanced grouting; the sections (through the broken zone hole section of the lime kiln) of the pile numbers DLI27+875-28+449 are carried out by adopting 1-section ground surface advanced grouting.

As shown in FIG. 2, the first section Z1 is formed by performing surface advanced grouting 490m, namely pile numbers DLI24+042-24+532, and the surface advanced grouting open position is positioned near tunnel pile numbers DLI23+808;

the surface advanced grouting 443m of the second section Z2, namely the sections with the pile numbers DLI24+502 to 24+945, and the surface advanced grouting tapping position is positioned near the tunnel pile number DLI25+223;

694m of the third section Z3 surface advanced grouting, namely pile number DLI 24+915-25+609 section, wherein the surface advanced grouting open hole position is positioned near tunnel pile number DLI25+862 due to the limitation of ground topography;

in addition, by combining the requirements of the ground 'L' -shaped directional drilling technology on the target front distance and the deflection gradient, the pile number DLI25+609-25+686 of the tunnel is in the deflection section range of the Z3 drilling, and the starting point pile number of the Z3 drilling entering the horizontal grouting section is in DLI25+609, so that the grouting reinforcement is not carried out on the pile number DLI25+609-25+686 of the ground surface advanced grouting;

the fourth Z4 surface advanced grouting 643m, namely the pile numbers DLI27+832-28+475, is positioned near the tunnel pile numbers DLI27+465.

Specifically, in the step B, aiming at 4 sections of earth surface advanced grouting sections, each section of earth surface advanced grouting adopts 3 drills to drill and grouting, the planned arrangement coordinates of the hole site planes of the 4 sections of earth surface advanced grouting drilling holes are shown in the following table 1,

TABLE 1

According to the past grouting reinforcement water shutoff construction experience, the thickness of the advanced consolidation grouting reinforcement ring is (0.5-1.0) times of the excavation diameter, the grouting curtain consolidation body mainly bears external water pressure, the factors such as water head reduction, actual allowable compressive strength of the reinforcement body and the like are considered, and the grouting reinforcement thickness can be calculated by referring to a fourth strength theory of a thick-wall cylinder.

According to the construction requirements of XX mountain tunnels, the maximum excavation diameter D=10.0m of the pile numbers DLI24+066-25+686 and DLI27+875-28+449, and the thickness theoretical calculated value of the grouting reinforcement ring is 9.8m according to the fourth strength theoretical calculation of the thick-wall cylinder; by combining the analysis and related construction experience, taking the construction difficulty and the danger degree of the high-pressure water-rich tunnel into consideration, taking the thickness of the grouting reinforcement ring as 10.0m in the stratum of the water-rich fracture zone;

the effective diffusion radius of the grouting slurry is 10m in the ground advanced grouting construction design, so that multiple factors such as 10m in construction cost, construction period, grouting ring thickness guarantee, full-section advanced grouting treatment and the like are comprehensively considered, 6 grouting holes are arranged temporarily, as shown in fig. 3, the grouting holes are arranged at positions 2.0m away from the excavation diameter, are evenly distributed on a 14 m-diameter hole distribution ring, and have hole spacing of 7.0m.

Specifically, in the step C, the pilot test hole is used for more accurately knowing the break zone of the rijiang-sisal fracture zone (pile number DLI 24+066-25+686 section) and the break zone of the lime kiln (DL I27+875-28+449 section), testing the process parameters of the ground surface 'L-shaped' drilling, the directional process, the grouting process, the injectability of the test grouting material, the grouting pressure and the like, summarizing the test hole construction experience, providing a certain basis for the subsequent construction, selecting a drill hole at each ground surface pilot grouting section as a test hole, carrying out the ground surface 'L' -directional drilling pilot exploration and drilling grouting test, and dynamically adjusting the grouting parameters and the construction range according to the test condition of the test hole and the progress of each working surface; taking a typical drilling hole of each grouting section as a pilot test hole, wherein the pilot test hole in the embodiment is temporarily drilled at the top of each grouting section, and the total number of the pilot test holes is 4; the specific construction tasks of the pilot test hole are as follows: the method comprises the steps of summarizing a test fracture zone and affecting an in-zone ground L-shaped drilling process, a directional process and a flower pipe lowering process; secondly, summarizing the technological parameters such as injectability, grouting pressure, grouting section height and the like of the experimental grouting material; according to the method, comprehensive measures such as drilling disclosure, rock debris analysis and hydrologic test are adopted to summarize and analyze the fracture zone of the section to be treated and the influence zone water enrichment and crushing degree, so that key prejudgment is provided for subsequent treatment.

Specifically, in the step D, the grouting material mainly adopts modified single-fluid cement slurry, and comprehensive clay cement slurry, modified urea-formaldehyde resin chemical slurry or modified silicate slurry can be selected for assistance according to site requirements; the modified single-fluid cement slurry takes cement and water as main raw materials, and the water-cement ratio is 1:1 or 0.8:1;

the modified urea-formaldehyde resin chemical slurry consists of the following raw materials in parts by volume: 50 to 60 parts of urea-formaldehyde resin, 10 to 20 parts of oxalic acid solution, 5 to 10 parts of ammonium chloride solution, 1 to 3 parts of polyacrylamide solution, 1 to 5 parts of sodium carboxymethyl cellulose solution, 1 to 3 parts of magnesium powder solution, 10 to 20 parts of water and 5 to 10 parts of polyacrylic emulsion;

the modified silicate slurry consists of the following raw materials in parts by volume: 50 to 70 parts of sodium silicate solution, 5 to 15 parts of ethylene glycol diacetate, 3 to 5 parts of butyrolactone, 3 to 5 parts of ethyl acetate, 1 to 3 parts of sodium polyphosphate solution, 1 to 3 parts of oxalic acid solution, 1 to 5 parts of formamide solution and 10 to 30 parts of water;

in the embodiment, the Z1 drill site pile number is 24+042-24+532, the Z2 drill site pile number is 24+502-24+945, and the Z3 drill site pile number is 24+915-25+609; the Z4 drilling site pile number is 27+832-28+475, modified single-liquid cement slurry is used in the pore-forming grouting and splitting compaction grouting stages, and the construction is performed in a mode of covering an orifice or lowering a slip type grouting stop plug to stop grouting; according to the requirements of site construction conditions, one or more of sodium chloride, triethanolamine, silica fume, water glass, bentonite, polymer and other materials are added into the modified single-liquid cement slurry to modify the slurry, so that the single-liquid cement slurry is subjected to quick setting, early strength, non-dispersion in water and other properties; the composite additive is selected according to the construction condition, wherein sodium chloride (5 wt%o of cement weight) and triethanolamine (0.5 wt%o of cement weight) are added to realize quick hardening and early strength, silica fume (5 wt%o-15 wt%o of cement weight) and water glass (5 wt%o-30 wt%o of cement weight) are added to improve slurry suspension property, and water glass and bentonite (10 wt%o-30 wt%o of cement weight) are added to remarkably improve slurry viscosity; the strength of the slurry consolidation body can be ensured by modifying the single-liquid cement slurry, the excessive diffusion of the slurry is reduced, the splitting compaction grouting effect is enhanced, and the purposes of reinforcing and plugging the broken belt are realized; the proportions of the modified single-fluid cement slurry are shown in the following table 2:

TABLE 2

Water to ash ratio	Water/L	Cement/kg	Composite additive	Pulping volume/m 3
					0.75∶1	3480	4640	Several of	5.0
1∶1	3767	3767	Several of	5.0
					1.25∶1	3985	3190	Several of	5.0

Pile number Z3 drilling site DLI24+915-25+609 section ground advanced grouting passes through part of limestone stratum grouting section, Z4 drilling site DLI27+832-28+475 section ground advanced grouting passes through part of mountain basalt stratum grouting section, and in the pore-forming grouting stage, part of comprehensive clay cement slurry is used; in the construction, the method of covering the orifice or lowering the slip type slurry stop plug to stop slurry is adopted; the comprehensive clay cement slurry takes clay slurry as a main component, and is mixed with a small amount of cement and water glass to prepare a multiphase suspension; in general, the volume percentages of the various components in the clay cement slurry are: 87% -96% of clay slurry, 3% -10% of cement and 1% -3% of water glass;

in the grouting process of sections 24+256 to 24+375 of the Z1 drilling site pile, a grouting section which has poor splitting compaction effect and is difficult to be penetrated by granular materials such as cement slurry is grouting by adopting modified silicate solution chemical slurry with relatively good permeability, wherein the volume of water glass in the modified silicate solution chemical slurry is 70% -80%, the volume of a curing agent is 8% -14%, the volume of water is 8% -22%, and the addition amount of solid particle additives is 10wt per mill-20 wt per mill of the weight of the water glass; the construction is carried out by adopting a mode of lowering a slurry stop plug to stop slurry;

The slurry injection amount of the grouting section is determined according to parameters such as the effective radial diffusion distance of the slurry, the average fracture rate of the grouting section and the like, and is calculated by adopting the following formula:

Q＝Aπ(R+r) ² LnB/m (2)

in the formula, Q-slurry injection amount (m ³ ) The method comprises the steps of carrying out a first treatment on the surface of the A, taking 1.2-1.5 of the super diffusion consumption coefficient of the slurry, and 1.40 in calculation; r is the effective diffusion distance (m) of the slurry, and 10.0m is calculated; r-the radius (m) of the grouting hole arrangement circle, and 7.0m is taken in calculation; l-grouting section length (m); n-average fracture rate of rock stratum, according to the result of early investigation, 6.5% of fracture rate of basalt stratum hole section is calculated, 9.0% of fracture rate of broken rock, breccia and affected stratum hole section is calculated, and 1.0% of fracture rate of broken rock stratum hole section is calculated; b, the filling coefficient of the slurry is 0.9-0.95, and 0.92 is calculated; m-serous fluid calculus rate, 0.80 is taken in calculation;

pile number DLI 24+042-24+532 section grouting section length 490m, pile number DLI 24+502-24+945 section grouting section length 443m, pile number DLI 24+915-25+609 section grouting section length 694m, pile number DLI 27+832-28+475 section grouting section length 643m; through calculation, the total grouting amount of the surface advanced grouting is 292967m ³ Wherein the one-liquid cement paste 234374m ³ 52734m of comprehensive clay cement slurry ³ SC1 modified water glass liquid-soluble chemical slurry 5859m ³ The method comprises the steps of carrying out a first treatment on the surface of the The average grouting amount per hole per meter is 19.2m ³ 。

In the embodiment, the ground directional drilling generally adopts a drilling construction scheme that holes are drilled vertically for a certain distance, then the holes are gradually increased to incline to the position that the drilling track is parallel to the axis of the tunnel, a sleeve is arranged at a non-grouting section, and a flowtube is arranged at a horizontal grouting reinforcement section for high-pressure grouting; in the step E, as the rock mass of the Lijiang-Camellia fracture zone and the lime kiln fracture zone is seriously crushed and muddy, shrinkage or hole collapse of the hole wall of the drill hole is easily caused, so that the grout stop plug is difficult to put down; the rock on the hole wall is weak, and the grout stop plug cannot press grout stop; the grouting device can be lowered and blocked, slurry can bypass the grouting stop plug during pressurized grouting, so that bypass grouting is formed, and high-pressure grouting can not be completed to strengthen a rock mass; therefore, the surface advanced grouting in the application adopts two-step method staged grouting, including bare hole water shutoff grouting and high-pressure compaction split grouting after the flowtube is lowered:

the vertical straight hole section is downwards provided with a steel sleeve with phi 244.5 multiplied by 8.94mm according to the diameter of the drilled hole, so that the straight hole surface soil section is prevented from collapsing and falling down, and the safe and rapid drilling of the stratum of the lower deflecting section is ensured; after the construction of the vertical straight hole section is finished, the construction of the deflecting section is carried out, after the construction of the deflecting section is finished, a phi 177.8X8.05 mm steel sleeve is put into the deflecting section according to the diameter of a drilled hole, the deflecting section sleeve is directly down to the surface of an orifice, and the overlapping part distance between the deflecting section sleeve and the straight hole section is used for preventing the deflecting section from collapsing and falling, so that the construction of the subsequent horizontal grouting section is ensured, and a large amount of slurry is prevented from being strung to a non-grouting section; the steel casing pipe and the flower pipe are made of petroleum casing pipes with higher strength, so that the problems of torsion fracture, cracking and the like of the steel pipe due to insufficient strength in the drilling grouting process are prevented;

The horizontal grouting section adopts a sectional forward grouting mode to drill a section of grouting and a section of grouting, and the grouting aims at plugging a large water passage and ensuring the drilling and pore forming of the horizontal grouting section; the length of the water blocking grouting section of the bare hole is 30-60 m, when the grouting pump quantity is reduced to 50L/min-60L/min and the grouting pressure reaches a final pressure value, the grouting operation of the hole section can be finished after the grouting pressure is stabilized by 20-30 min; the grouting material mainly adopts modified single-fluid cement slurry, the grouting ending pressure is set to be 3MPa-6MPa according to the analysis and prediction of the external water pressure of the poor geological hole section, and a large-flow low-pressure grouting mode is adopted to create conditions for the lowering of the flowtube in the horizontal grouting hole; after the water shutoff grouting is completed, a flowtube is placed under the horizontal grouting section, so that conditions are created for high-pressure compaction split grouting in the next stage;

in order to ensure the reinforcing effect, high-pressure compaction split grouting adopts a high-pressure quantitative grouting mode; the grouting material adopts modified single-liquid cement slurry and comprehensive clay cement slurry, and adopts modified urea resin chemical slurry material aiming at a special grouting section; after the water shutoff grouting is completed, the horizontal grouting section lowers a flower pipe, the flower pipe section and the deflecting section are overlapped for 20m, the specification of the flower pipe is originally set to be phi 133 multiplied by 6mm, and the dynamic adjustment is carried out according to the construction condition; after the pipe fixing of the pipe is completed, the pipe is internally injected with sectional forward type or backward type grouting, the grouting stop plug is used for sectional grouting stop, and the surrounding stratum is split, compacted and reinforced; the length of the grouting section in the compaction splitting grouting stage is reduced to 10m-30m, and the grouting section can be dynamically adjusted according to the construction condition in the construction process; when the grouting pump quantity is reduced to 50L/min-60L/min and the grouting pressure reaches the end pressure (final pressure) value, the grouting operation of the hole section can be ended after the grouting pressure is stabilized by 20 min-30 min; grouting pressure control in the compaction splitting grouting stage mainly depends on factors such as hydrostatic pressure, ground stress and the like of a drilling stratum to be overcome by splitting grouting, and grouting pressure is dynamically adjusted according to stratum crushing conditions and grouting quantity; the earth surface advanced grouting hole section burial depth is about 500m-600m, meanwhile, when single-fluid cement slurry is used for grouting with the flow of about 200L/min under the condition of the earth surface grouting burial depth of 500m, the pipe resistance and the pressure loss are about 4MPa, meanwhile, the slurry column pressure is about 7.5MPa (500 m Gao Yezhu), the factors are comprehensively considered, the grouting end pressure is initially set to be 14+/-0.5 MPa, the end pressure value is a preliminary calculated value, and the dynamic adjustment can be carried out according to the test condition and the actual construction condition of a test hole;

In the step E, grouting effect inspection and evaluation are mainly performed on impervious performance and physical and mechanical indexes, and the advanced grouting effect of the earth surface is comprehensively analyzed and judged by combining multiple aspects of geophysical tests such as drilling grouting process parameter analysis, pressurized water test data comparison, in-hole video recording and the like and pressurized water test detection; the water permeability q is less than or equal to 3Lu, the qualification rate of the test section is not less than 90%, the water permeability of the unqualified test section is not more than 150% of the design specification, the distribution is not concentrated, and the grouting quality can be evaluated as qualified.

The drilling length of the vertical straight hole section of each grouting drilling hole is determined according to the depth of the surface soil section, in the embodiment, the drilling length of the vertical straight hole section of each grouting drilling hole is 50m, the drilling length of the deflecting section is 567m-807m, and the drilling length of the horizontal grouting section is 443-694m; correspondingly, the length of the vertical section petroleum casing pipe is 50m, the length of the deflecting section petroleum casing pipe is 617m-857m, the length of the horizontal grouting section steel casing pipe is 463m-714m, and specifically, the statistics of the surface advanced grouting drilling length and the design length of the lowered steel casing pipe and the steel flowtube are shown in the following table 3:

TABLE 3 Table 3

Therefore, according to the drilling length, grouting process and the like of 4-section surface advanced grouting, the main engineering quantity of the surface advanced grouting is shown in the following table 4,

TABLE 4 Table 4

According to the two tables, the whole construction section is divided into 4 sections, and each drilling hole, petroleum casing pipe and flower pipe of each drilling site are adaptively and finely designed, so that small-section fine grouting is conveniently performed, the slurry diffusion range is ensured, meanwhile, a good grouting effect is ensured, and the phenomenon that partial grouting hole sections are not or less in grouting amount due to uneven surrounding rock grouting is avoided.

Each drilling site is provided with an even number of grouting drilling holes and a plurality of drilling machines, each drilling machine is used for constructing 2 spatially adjacent grouting holes, the two adjacent grouting holes are constructed in two orders, the construction procedures of each grouting hole are consistent, in the embodiment, each drilling site is provided with 6 grouting drilling holes and 3 drilling machines, as shown in fig. 4, and each drilling hole is constructed according to the following construction procedures:

and (3) construction: after drilling to 50m by adopting a phi 311mm drill bit, continuously drilling downwards by 1.0m-2.0m by adopting a small first-stage drill bit so as to deposit rock and earth dust in the hole; then a phi 244.5mm 8.94mm sleeve is put down, and a flange is welded at the orifice to connect the grouting pipe; firstly pumping clear water by using a grouting pump, in the water pressing process, the wall of the outer edge hole of the sleeve is subjected to water returning phenomenon, then adding an additive into pure cement slurry for grouting (the concentration of the cement slurry is generally 0.6:1, the dosage of sodium chloride and triethanolamine respectively accounts for 5 per mill and 0.5 per mill of the dosage of the cement), stopping grouting after the outer edge of the sleeve returns to thick slurry, and quantitatively pressing the clear water; after 12 hours, cement slurry on the 1.0m-1.5m distance from the bottom in the sleeve is swept out, the maintenance is continued for 24h-36h, the hole is swept to the original depth, after the water pressure test in the sleeve is carried out, the water does not return outside the sleeve and the requirement of pipe fixing quality is met, the pipe fixing is considered to be qualified, otherwise, the solidification is continued;

And (3) two-step construction: drilling by adopting a drill bit with the diameter of 215.9mm, and then continuously drilling downwards by using a small first-stage drill bit for 1.0m-2.0m so as to deposit rock and earth dust in the hole; then the seamless steel tube is put down, after the sleeve is determined to be lowered to a preset depth, a slurry stop plug is put down in the sleeve, the slurry stop plug is generally lowered to the bottom of the sleeve, and is 3m-4m away from the bottom, firstly, grouting pump is used for pumping clean water, the slurry stop effect is checked, if water return phenomenon exists in the hole, the plug is started to be lowered again until water does not return; in the water pressing process, the water returning phenomenon occurs on the wall of the outer edge of the sleeve, after the water returning is clarified, pure cement slurry is added with an additive for grouting (the concentration of the cement slurry is generally 0.6:1, the dosage of sodium chloride and triethanolamine respectively accounts for 5 per mill and 0.5 per mill of the dosage of the cement), and after the thick slurry is returned from the outer edge of the sleeve, grouting is stopped, and clean water is quantitatively pressed in; and (3) starting the plug after 6-8 hours, cleaning out cement paste in the sleeve at a distance of 1.0-1.5 m from the bottom after 12 hours, continuing to maintain for 24-36 hours, cleaning the hole to the original depth, and after the water pressure test in the sleeve is carried out, the water does not return outside the sleeve and meets the requirement of pipe fixing quality, considering the pipe fixing is qualified, otherwise, continuing to fix.

Horizontal grouting section construction: drilling a section and grouting a section by adopting sectional forward type bare hole grouting, and starting to drill the next section and grouting after grouting pressure and flow meet the technical requirements until grouting of all grouting sections is finished;

And (3) lowering a three-flowering pipe: after the grouting construction of the bare hole grouting section is completed, a flower pipe string is lowered in the drilled hole, the hole bottom is up to the hole opening, and the pipe is fixed; the grouting pipe is continuously lowered in a pipe throwing mode, and after the grouting pipe is lowered to a designed position, a special filling material is adopted to fill an annular space between the grouting sleeve and the wall of the drilling hole immediately; the filling material not only can meet the strength requirement of the solid pipe slurry stopping, but also can be broken down by slurry pressure to a certain extent, and meets the aim of penetrating into the stratum to realize reinforcement; the annular space filling material is required to meet the pumping requirement, the water extraction rate is less than 5%, the initial setting time is 30 min-1 h, the final setting time is 6h-10h, the early strength can be controlled to be 0.5MPa-2.0MPa, the consumption of slurry is required to be monitored in the drilling process of the crushing section, and the concentration and the slurry formula of the slurry are adjusted according to the drilling condition; the slurry treatment is carried out by adopting a method of combining manual sand bailing and sedimentation of a slurry tank so as to clean useless solid phase in the slurry on the whole surface, keep the stability of the slurry performance and achieve virtuous circle;

grouting a flower pipe: the method is consistent with the bare hole grouting process, and then the section high-pressure splitting and compaction grouting are carried out on the area of which the bare hole grouting is finished through the flowtube;

And (3) hole sealing: sealing the whole holes by using single-liquid cement slurry with the water-cement ratio of 0.6:1;

after the construction is finished, the grouting treatment of the section of the earth surface is finished; the construction procedures of each drilling machine are independent and related to each other.

In order to accelerate the drilling construction progress and improve the drilling track control precision, the drilling construction adopts the combined drilling and wireless inclinometry while drilling directional drilling technology to construct the drilling; the wireless inclinometer can measure in time in the drilling process, the installation and the operation are convenient, no cable is needed to transmit data, namely, the mud pulse generator sends the data measured by the in-hole probe to the ground under the condition of no drilling, and the real-time hole body parameters are obtained after the data are acquired and processed by the computer system; the inclinometer can measure the inclination angle, azimuth angle and toolface angle of the hole body in the drilling process, and provide hole body parameters for drilling of high-inclination holes and horizontal holes in time; the inclinometer not only improves the inclinometry and orientation precision, but also can timely adjust the orientation design scheme along with the real-time monitoring of the orientation parameters of drilling operation, and can simultaneously carry out a composite drilling mode of combining sliding orientation drilling and rotary drilling, thereby improving the mechanical drilling speed and greatly improving the drilling construction efficiency; the construction track of the drilling hole is effectively ensured to be matched with the design track, and the occurrence of complex situations can be effectively prevented; the wireless inclinometer is composed of two parts, namely ground equipment and an in-hole measuring instrument, and is a conventional technology in the field of drilling and is not repeated here; drilling deviation control measures: in the drilling construction process, the drilling track monitoring is enhanced after the hole depth exceeds 50m, and data is timely filled on a drilling deflection plane graph so as to timely adjust drilling parameters or take corresponding directional deviation correction measures according to the drilling deflection condition and strictly control the drilling track; if the drilling deflection is severe, the partial hole sealing can be redirected if necessary.

Specifically, as shown in fig. 1 and 5, the surface grouting is to pour the slurry into the stratum by a surface grouting pump under high pressure, and the slurry is solidified in the stratum to form a stone body; the grouting system consists of a grouting pump, a grouting pipeline, a grouting stopping tool and the like, wherein a schematic diagram of 6 drilling construction of each drilling site is shown in fig. 1, 6 drilling holes are uniformly distributed on the periphery of a main tunnel, and the lining structure 13 of the main tunnel in fig. 1 represents the range of part of the main tunnel; fig. 5 comprises a control cabinet 1, a cement tank 2, a screw conveyer 3, a hopper 4, a primary stirring tank 5, a secondary stirring tank 6, a slurry conveying pipe 7, a slurry pump 8, a drilling machine 9, a slurry injection hole 10, a sleeve 11 and a injected stratum 12; after the grouting system is formed, a pressurized water test is performed first, and the tightness and safety of the system are tested; when grouting is performed by adopting an orifice gland and a lower grouting stop plug, after drilling is completed and punching is performed, installing an orifice grouting stop device or the lower grouting stop plug to the middle lower part of the sleeve section, and testing whether grouting of a grouting system is normal or not by using pressurized water; the method comprises the steps of routine pressurized water 20 min-30 min before grouting, obtaining hydrogeological parameters, knowing the permeability, connectivity and crack development degree of an aquifer, further reasonably adjusting parameters in the grouting process, and checking whether a grouting system works normally or not; after grouting, the routine pressurized water is 10 min-30 min, so that the grouting effect is checked by comparing with pressurized water before grouting, and a grouting pipeline is cleaned, so that the pipeline is smooth and convenient to use next time; when grouting, the grouting pressure and flow are observed and recorded by adopting the grouting automatic recorder, and the automatic recorder is corrected before each grouting, so that the data acquisition precision is ensured.

In the embodiment, the poor geological hole sections of partial hole sections of the XX mountain tunnel are mainly located in the Lijiang-Jianchuan fracture zone and the lime kiln fracture zone, the total length is about 2200m, the ground surface advanced grouting treatment is carried out on the two poor geological hole sections by adopting the ground surface L directional drilling grouting technology, the hole sections are effectively reinforced in advance, the straight line construction period is not occupied, the construction risk is small, compared with the conventional in-cylinder advanced grouting, the expected grouting effect is better by adopting the ground surface advanced grouting, the month comprehensive footage is higher, the construction cost is at the bottom, and the comparison analysis of the ground surface advanced grouting and the in-hole advanced grouting scheme is shown in the following table 5; in-hole reinforcement is performed according to the ground reinforcement effect in the excavation process, the advanced grouting of the earth surface is used as the main material, the advanced geological prediction and the advanced support in the hole are complementary, the targeted advanced grouting in the hole is used as the auxiliary material, the success rate is high, the comprehensive risk is low, and the principle of safety, rapidness and stability is met.

Table 5 table surface advanced grouting and in-hole advanced grouting scheme comparison analysis table

It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While the obvious variations or modifications which are extended therefrom remain within the scope of the claims of this patent application.

Claims (10)

1. A method for advanced pretreatment of the ground of a poor geological stratum of a deep-buried long large tunnel is characterized by comprising the following steps:

step A, determining the surface advanced grouting range, namely performing ground exploration along the line of a fracture zone on a main tunnel planning route of a tunnel, and determining advanced grouting tunnel sections, grouting section division of the grouting sections and positions near the surface of the axis of the main tunnel, wherein the positions are provided with drilling site construction conditions;

step B, arranging surface advanced grouting holes: determining the arrangement coordinates of grouting drilling hole site planes of grouting sections of each grouting hole section, arranging ground drilling sites, determining the thickness of a grouting reinforcement ring, and determining the arrangement of grouting hole sections;

step C, arranging pilot test holes for surface advanced grouting: selecting a drilling hole as a pilot test hole, and performing ground L-shaped directional drilling advanced exploration and drilling grouting test;

step D, selecting earth surface advanced grouting materials and calculating grouting quantity;

e, grouting the ground: the vertical straight hole section and the deflecting section both adopt sleeve pipe retaining walls, the horizontal grouting section firstly adopts a sectional advancing grouting mode to carry out water plugging grouting of a bare hole, then the flowtube is lowered, and the high-pressure quantitative mode is adopted to carry out compaction and splitting grouting of surrounding rocks around a tunnel, so that an anti-seepage consolidation curtain ring is formed.

2. The advanced ground pretreatment method for the poor geological strata of the deep-buried long tunnel according to claim 1, wherein the step E further comprises grouting effect inspection, and the advanced ground grouting effect is judged by combining drilling grouting process parameter analysis, pressurized water test data comparison, geophysical prospecting test and pressurized water test detection multi-aspect comprehensive analysis.

3. The advanced ground pretreatment method for the bad geological strata of the deep-buried long and large tunnel according to claim 1, wherein according to the characteristics that the gradient of the tunnel is small, the tunnel passes through the bad geological strata in a nearly horizontal state, the excavation section is round or nearly round, grouting sections of grouting holes are nearly horizontal in the same direction as the trend of the tunnel, and the grouting holes are distributed outside the excavation diameter of the main tunnel and are uniformly distributed along the circumference.

4. The advanced ground pretreatment method for the poor geological strata of the deep-buried long and large tunnel according to claim 3, wherein the length of the tunnel penetrating through the poor geological strata exceeds 1000m, the tunnel is divided into a plurality of grouting sections, typical drilling holes are taken as pilot test holes, and grouting parameters and construction range are dynamically adjusted according to the test conditions of the test holes and the progress of each working face.

5. The advanced ground pretreatment method for poor geological formations of a deep-buried long and large tunnel according to claim 1, wherein the drilling length of a vertical straight hole section of each grouting drilling hole is determined according to the depth of a surface soil section, the drilling length of a deflecting section is determined according to the depth of the buried long and large tunnel and the target front distance, and the drilling length of a horizontal grouting section is 400-800m.

6. The advanced ground pretreatment method for poor geological formations of a deep-buried long and large tunnel according to claim 1, wherein a vertical straight hole section is lowered into a steel sleeve with phi 245+/-0.5 mm multiplied by 9+/-0.06 mm according to the diameter of a drilled hole, a deflecting section is lowered into a steel sleeve with phi 178+/-0.5 mm multiplied by 8+/-0.05 mm according to the diameter of the drilled hole, and the standard of the pipe with phi 133+/-0.5 mm multiplied by 6+/-0.05 mm; the sleeve pipe of the deflecting section is directly down to the surface of the orifice, and is overlapped with the straight hole section by 20m at a part distance, and the flower pipe section is overlapped with the deflecting section.

7. The advanced ground pretreatment method for poor geological formations of a deep-buried long and large tunnel according to claim 1, wherein in a horizontal grouting section, each small grouting section in the sectional forward grouting is 30-60 m long, a grouting material adopts modified single-liquid cement slurry, and comprehensive clay cement slurry, modified urea resin chemical slurry or modified silicate slurry is selected for assistance according to field requirements; the grouting end pressure is 3MPa-6MPa, when the grouting pump quantity is reduced to 50L/min-60L/min and the grouting pressure reaches the end pressure final pressure value, the grouting operation of the hole section can be ended after the grouting pressure is stabilized for 20min-30 min; the length of the grouting section in the compaction splitting grouting stage after the flowtube is lowered is reduced to 10-30 m, the grouting end pressure is dynamically adjusted according to the stratum breaking condition and the grouting amount, and when the grouting pump amount is reduced to 50-60L/min and the grouting pressure reaches a final pressure value, the grouting operation of the hole section can be ended after the grouting pressure is stabilized for 20-30 min.

8. The advanced pretreatment method for the ground of the poor geological formation of the deep-buried long-and-large tunnel according to claim 7 is characterized in that the modified single-liquid cement slurry takes cement and water as main raw materials, the water-cement ratio is (1:1) - (0.8:1), and one or more of sodium chloride, triethanolamine, silica fume, water glass, bentonite and polymer materials are added according to the actual requirements of the site to modify the slurry;

wherein the addition of sodium chloride is 3-5 wt% of the weight of the cement, the addition of triethanolamine is 0.3-0.5 wt% of the weight of the cement, the addition of micro silicon powder is 5-20 wt% of the weight of the cement, the addition of water glass is 5-50 wt% of the weight of the cement, the addition of bentonite is 10-80 wt% of the weight of the cement, and the addition of polymer is 1-6 wt% of the weight of the cement;

the modified urea-formaldehyde resin chemical slurry consists of the following raw materials in parts by volume: 50 to 60 parts of urea-formaldehyde resin, 10 to 20 parts of oxalic acid solution, 5 to 10 parts of ammonium chloride solution, 1 to 3 parts of polyacrylamide solution, 1 to 5 parts of sodium carboxymethyl cellulose solution, 1 to 3 parts of magnesium powder solution, 10 to 20 parts of water and 5 to 10 parts of polyacrylic emulsion;

the modified silicate slurry consists of the following raw materials in parts by volume: 50 to 70 parts of sodium silicate solution, 5 to 15 parts of ethylene glycol diacetate, 3 to 5 parts of butyrolactone, 3 to 5 parts of ethyl acetate, 1 to 3 parts of sodium polyphosphate solution, 1 to 3 parts of oxalic acid solution, 1 to 5 parts of formamide solution and 10 to 30 parts of water.

9. The advanced ground pretreatment method for poor geological formations of deep-buried long and large tunnel according to claim 1, wherein the main tunnel is of a circular section, the diameter of the net section is 5m-10m, the buried depth is 400m-1000m, and the thickness of a grouting reinforcement ring is 6m-12.0m.

10. The advanced pretreatment method for the poor geological formation ground of the deep-buried long and large tunnel according to claim 9, wherein each drilling site is provided with an even number of grouting drilling holes and a plurality of drilling machines, each drilling machine is used for constructing 2 spatially adjacent grouting holes, the construction is carried out in two sequences, and the construction procedures of each grouting hole are consistent; the construction process of each grouting hole comprises the following steps:

and (3) construction: constructing a drill hole with the diameter of 311.1mm, and lowering a sleeve with the diameter of 244.5mm and the diameter of 8.94mm to fix the pipe;

and (3) two-step construction: continuously downwards constructing a drill hole with the diameter of 215.9mm in the first casing pipe, and downwards placing a casing pipe with the diameter of 177.8mm and a fixed pipe with the diameter of 8.05 mm;

horizontal grouting section construction: drilling a section and grouting a section by adopting sectional forward type bare hole grouting, and continuously drilling the next section and grouting after grouting pressure and flow meet the technical requirements until grouting of all grouting sections is finished;

and (3) lowering a three-flowering pipe: after the grouting construction of the bare hole grouting section is completed, a flower pipe is lowered in the drilled hole, the hole bottom is up to the hole opening, and the pipe is fixed;

Grouting a flower pipe: the method is consistent with the bare hole grouting process, and then the section high-pressure splitting and compaction grouting are carried out on the area of which the bare hole grouting is finished through the flowtube;

and (3) hole sealing: and sealing the whole holes by using single-liquid cement slurry with the water-cement ratio of 0.6:1.

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