阅读说明：本技术 一种运营隧道强富水松软围岩内安全快速堵水加固方法 (Safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of operation tunnel ) 是由 张庆松 潘光明 李术才 杨磊 林春金 刘春国 张洪顺 王凤伟 于 2019-10-24 设计创作，主要内容包括：本发明公开了一种运营隧道强富水松软围岩内安全快速堵水加固方法,包括如下步骤：通过钻孔注浆,将隧道围岩深部的储导水空间中的水替换,进行充填封堵；然后再向隧道围岩浅部进行帷幕注浆加固。A类钻孔先封堵围岩内储导水构造,通过浆液充填把储导水构造内的地下水替换掉,把水赶到被加固围岩范围之外,把围岩强富水状态转变为饱水状态或贫水状态。B类钻孔对帷幕注浆范围内的处于饱(贫)水状态的松软围岩进行注浆加固,提高其整体强度,整体稳定性,降低其渗透系数。(The invention discloses a safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of an operation tunnel, which comprises the following steps: replacing water in a water storage and guiding space at the deep part of the tunnel surrounding rock by drilling and grouting to fill and plug; and then curtain grouting reinforcement is carried out on the shallow part of the surrounding rock of the tunnel. The class A drilling hole firstly seals the water storage and guide structure in the surrounding rock, underground water in the water storage and guide structure is replaced through slurry filling, water is driven to the outside of the range of the reinforced surrounding rock, and the strong water-rich state of the surrounding rock is converted into a water-saturated state or a water-poor state. The B-type drill hole performs grouting reinforcement on the soft surrounding rock in a full (poor) water state within the curtain grouting range, so that the overall strength and the overall stability of the soft surrounding rock are improved, and the permeability coefficient of the soft surrounding rock is reduced.)

1. A safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of an operation tunnel is characterized by comprising the following steps: the method comprises the following steps:

replacing water in a water storage and guiding space at the deep part of the tunnel surrounding rock by drilling and grouting to fill and plug; and then curtain grouting reinforcement is carried out on the shallow part of the surrounding rock of the tunnel.

2. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 1, characterized in that: in the filling and plugging step, class A drilling holes are constructed on the surfaces of the two liners, and when the class A drilling holes reveal a water storage and guide structure in the deep part of the surrounding rock, grouting is performed.

3. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 2, characterized in that: in the A-type drilling construction process, the water inflow amount is more than 3m³Grouting can be carried out at the time of/h;

or the grout used for the A-type drilling grouting comprises single-fluid grout and cement-based double-fluid grout, and the density of the single-fluid grout is 1.5-1.75g/cm³The cement-based double-liquid slurry is cement-water glass slurry or cement-GT slurry;

furthermore, in the cement-water glass slurry, the water glass modulus ranges from 2.4 to 3.0, and the Baume degree ranges from 35 to 42.

4. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 3, characterized in that: when the grouting pressure is high, the density of the single-liquid cement slurry is high, and when the grouting pressure is low, the density of the single-liquid cement slurry is low.

5. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 3, characterized in that: when the A-type drilling grouting is carried out, single-fluid cement slurry is injected firstly.

6. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 5, characterized in that: when the single-liquid cement slurry is injected for 60min, the grouting pressure is not increased and the grouting rate is not reduced, replacing the single-liquid cement slurry with cement-based double-liquid slurry, when the grouting pressure exceeds 45-55% of the designed final pressure and has a pressure increasing trend, replacing the single-liquid cement slurry with the single-liquid cement slurry, and when the grouting pressure is lower than a set value, replacing the single-liquid cement slurry with the cement-based double-liquid slurry, and repeating the steps;

further, the class A drilling grouting finally takes single-fluid cement slurry as slurry after the grouting is finished;

further, when the grouting pressure of the A-type drilling reaches the design final pressure, intermittent grouting with the minimum pump amount is adopted until the grouting pressure lasts for more than 5min at the design final pressure, and grouting is stopped.

7. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 2, characterized in that: the design final pressure of the A-type drilling grouting is 2.5-4 MPa;

or before the A-type drilling grouting, the method also comprises the step of constructing a grouting sleeve.

8. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 2, characterized in that: after the A-type drilling grouting construction is finished, constructing curtain grouting, and constructing B-type drilling holes on the surfaces of the two linings;

furthermore, the construction depth of the B-type drilling is 10-15m, and the maximum value of the construction depth of the A-type drilling is 2 times of the construction depth of the B-type drilling.

9. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 8, characterized in that: in the drilling process of B-type drilling, the water flow is 1-3m³When water gushing or hole collapse occurs and the drilling depth reaches 3m, the 3m can be used as a grouting section;

if the water inflow amount is less than 1m when the hole is drilled³And/h or when the hole wall is stabilized by drilling and does not collapse or fall, taking every 5m as a grouting section.

10. The safe and rapid water plugging and reinforcing method in the strong water-rich soft surrounding rock of the operation tunnel according to claim 9, characterized in that: the method comprises the following steps that (1) single-liquid cement slurry is injected into a B-type drill hole, when the volume of the injected slurry exceeds 2 times of the volume of a grouting drill hole and the grouting pressure is smaller than the design final pressure, cement-based double-liquid slurry is replaced until the grouting pressure reaches the design final pressure;

and further, the B-type drilling grouting takes cement-based double-fluid slurry as slurry at the end of grouting.

Technical Field

The invention relates to the technical field of tunnel water plugging reinforcement, in particular to a safe and rapid water plugging reinforcement method in strong water-rich soft surrounding rock of an operation tunnel.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

In recent years, with the influence of abnormal climate in the south, geological disasters are frequent, and economic and life safety is greatly threatened. Some tunnels with long operation time have diseases which are mainly reflected in water and mud outburst, damages to a secondary lining structure, roads and the like, and serious influences on traffic safety. The main reason for the water-bursting and mud-bursting geological disasters is that serious geological structures such as underground water-rich karst, underground river and the like develop in the surrounding rocks, the geological structures become underground water storage spaces and invade and damage the tunnel surrounding rocks to burst water; when strong and rich water meets soft surrounding rocks, the soft surrounding rocks lose the cementing power and have poor stability, so that the tunnel structure is seriously influenced. When the soft surrounding rock is carried by water and is broken out, a collapse pit often appears on the earth surface, and great damage is caused to the environment. The difficulty in treating the geological disasters is mainly reflected in the phenomena that when underground water is exposed in grouting and drilling, the flow rate of the underground water is high, the pressure is high, a large amount of silt is carried to flush out, injected slurry is difficult to preserve and solidify, and even if the slurry is solidified, the slurry is loosened and flushed by gushing water under the disturbance of nearby drilling construction. Because the two lining structures are damaged by water inrush and mud inrush, the two linings lose the protection capability, the two linings of the tunnel crack and fall off due to drilling grouting disturbance, and the damaged two lining structures are difficult to bear the influence of grouting pressure. According to the conventional curtain grouting method, the safety and the grouting effect are difficult to ensure. Therefore, the treatment of the serious water-mud-outburst disaster-causing surrounding rocks is a great technical problem which troubles engineering technicians.

Disclosure of Invention

In order to solve the technical problems in the prior art, the invention aims to provide a safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of an operation tunnel. Through the sequential grouting of the two types of drilling holes, the blindness and the repeatability of curtain grouting are reduced, and the grouting operation is safer.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of an operation tunnel comprises the following steps:

replacing water in a water storage and guiding space at the deep part of the tunnel surrounding rock by drilling and grouting to fill and plug; and then curtain grouting reinforcement is carried out on the shallow part of the surrounding rock of the tunnel.

The method comprises the steps of filling and plugging a water storage and guide structure deep in the strong water-rich surrounding rock through drilling and grouting, replacing water in the water storage and guide structure, forming a stone body with certain strength after consolidation, filling a structural space, plugging gushing water, isolating the water filling strength of underground water in a shallow layer reinforced range of the tunnel surrounding rock, and changing the shallow layer grouting reinforcement range from strong water-rich water to a water-saturated or water-poor state; and the concreted stone body has certain strength and plays a certain pull force on the tunnel surrounding rock through the grouting pipe. When the shallow surrounding rock of the tunnel is subjected to curtain grouting reinforcement by using the drill holes, the shallow surrounding rock can be prevented from cracking and falling under grouting disturbance, and the surrounding rock is prevented from being loosened under the disturbance of drilling construction in the grouting process and further being broken down by the gushing water due to plugging of the gushing water.

In some embodiments, in the filling and plugging step, a class A drilling hole is constructed in the surface of the two liners, and when the class A drilling hole reveals a water storage and guide structure in the deep part of the surrounding rock, grouting is performed.

Further, type A drilling constructionIn the process, the water inflow amount is larger than 3m³Grouting can be carried out at the time of/h.

Furthermore, the grout used for the type A drilling grouting comprises single-fluid grout and cement-based double-fluid grout, wherein the density of the single-fluid grout is 1.5-1.75g/cm³The cement-based double-liquid slurry is cement-water glass slurry or cement-GT slurry.

Furthermore, in the cement-water glass slurry, the water glass modulus ranges from 2.4 to 3.0, and the Baume degree ranges from 35 to 42.

Furthermore, when the grouting pressure is high, the density of the single-liquid cement paste is high, and when the grouting pressure is low, the density of the single-liquid cement paste is low.

Furthermore, during grouting of the A-type drill hole, single-fluid cement slurry is injected firstly. The grout used for the class A drilling grouting comprises single-fluid cement grout and cement-based double-fluid grout, wherein the cement-based double-fluid grout is formed by adding another grout by taking the cement grout as a base fluid in the process of pouring the single-fluid cement grout. Therefore, the single-liquid cement slurry or the cement-based double-liquid slurry is injected firstly.

Furthermore, after the single-liquid cement slurry is injected for 60min, the grouting pressure is not increased, and the grouting rate is not reduced, the single-liquid cement slurry is replaced by the cement-based double-liquid slurry, when the grouting pressure exceeds 45-55% of the designed final pressure and has a pressure increasing trend, the single-liquid cement slurry is replaced by the single-liquid cement slurry, when the grouting pressure is lower than a set value, the cement-based double-liquid slurry is replaced, and the steps are repeated and alternated.

The class A drilling grouting aims at filling gaps of deep water storage and guide structures, and the used grout is mainly single-liquid grout and plays a role in filling and strengthening, namely the high consolidation strength of the single-liquid grout after consolidation is utilized, and after the grout is filled into the water storage and guide structures, the water storage and guide structures can be prevented from being filled with water by underground water again. The purpose of using the cement-based double-liquid slurry is that when the external water storage and guide structure with stronger communication capacity with the treatment range is encountered, the single-liquid cement slurry can continuously diffuse outwards and run off, and at the moment, the anti-dispersion, quick-setting and early-strength characteristics of the cement-based double-liquid slurry can be utilized, and the cement-based double-liquid slurry is injected into the water storage and guide structure and then quickly set and accumulated in the structure to prevent the single-liquid cement slurry from diffusing and running off towards the far end. The cement-based double-fluid slurry plays a role of auxiliary slurry. The method for grouting in the water storage and guide structure at the deep part of the surrounding rock adopts a single-liquid-slurry and cement-based double-liquid-slurry alternate grouting mode, so that the filling of single-liquid cement slurry in the gap of the water storage and guide structure can be ensured, and the loss of the single-liquid cement slurry can be effectively prevented.

Furthermore, the type A drilling grouting finally takes single-fluid cement slurry as the slurry at the end of the grouting. As the cement paste has no quick setting characteristic, the cement paste has stronger permeability and diffusion capacity than double-liquid paste. Therefore, when the grouting is nearly finished, the single-fluid cement slurry is finally used as the slurry at the end of the grouting, and the permeation, diffusion and reinforcement effects of the slurry on the injected surrounding rock can be further exerted. This is the purpose of injecting single-fluid cement slurry at the beginning and the end of grouting.

And further, when the grouting pressure of the A-type drilling reaches the design final pressure, intermittent grouting with the minimum pump amount is adopted until the grouting pressure lasts for more than 5min at the design final pressure, and grouting is stopped.

Furthermore, the design final pressure of the A-type drilling grouting is 2.5-4 MPa. When the secondary lining structure is damaged and the compressive strength is lower or the drilling depth is shallower, the final pressure is designed to be 2.5 MPa; when the two lining structures are not damaged, the compressive strength is high, and the drilling hole is deep for grouting, the designed final pressure is high value, namely 4 MPa.

Further, before the A-type drilling grouting, the method also comprises the step of constructing a grouting sleeve.

In some embodiments, after the class A drilling grouting construction is completed, a curtain grouting is constructed, and a class B drilling hole is constructed on the surface of the two linings.

Furthermore, the construction depth of the B-type drilling is 10-15m, and the maximum value of the construction depth of the A-type drilling is 2 times of the construction depth of the B-type drilling. The underground water is blocked outside the curtain grouting reinforcement range, the pressure damage of the underground water in the external area after grouting to the curtain grouting reinforcement area is prevented, and generally the depth of the surrounding rock controlled by the type A drilling is about 2 times of the depth of the curtain grouting reinforcement ring. The method aims to effectively isolate the pressure damage of the underground water to the surrounding rock in the reinforced area.

Furthermore, during the drilling process of B-type drilling, water is disclosedThe flow rate is 1-3m³When water gushing or hole collapse occurs and the drilling depth reaches 3m, the 3m can be used as a grouting section;

if the water inflow amount is less than 1m when the hole is drilled³And/h or when the hole wall is stabilized by drilling and does not collapse or fall, taking every 5m as a grouting section.

And further, injecting single-liquid cement slurry into the B-type drill hole, and replacing cement-based double-liquid slurry when the volume of the injected slurry exceeds 2 times of the volume of the injected drill hole and the grouting pressure is less than the designed final pressure until the grouting pressure reaches the designed final pressure.

And further, the B-type drilling grouting takes cement-based double-fluid slurry as slurry at the end of grouting.

The invention has the beneficial effects that:

(1) the invention creatively provides a classification method and a construction sequence for grouting and drilling in strong water-rich soft surrounding rock of an operation tunnel. The class A drilling hole firstly seals the water storage and guide structure in the surrounding rock, underground water in the water storage and guide structure is replaced through slurry filling, water is driven to the outside of the range of the reinforced surrounding rock, and the strong water-rich state of the surrounding rock is converted into a water-saturated state or a water-poor state. The B-type drill hole performs grouting reinforcement on the soft surrounding rock in a full (poor) water state within the curtain grouting range, so that the overall strength and the overall stability of the soft surrounding rock are improved, and the permeability coefficient of the soft surrounding rock is reduced.

(2) The two types of drilling play different roles. Each has pertinence and specific purpose.

(3) Through two types of drilling sequential grouting, blindness and repeatability of previous drilling grouting are reduced, grouting is more clear and quicker, grouting data can be analyzed more conveniently, grouting operation is safer, and the effect is better.

(4) The method can also be applied to the treatment of geological disasters of tunnel construction under the similar hydrogeological conditions, and is distinguished by building a grout stopping wall at the tunnel face, wherein the grout stopping wall is plain concrete containing reinforcing steel bars, and the strength mark is not lower than C30; the outer surface of the grout stopping wall serves as a grouting drilling positioning and hole opening position, and the function and the effect of the grouting drilling positioning and hole opening positioning device are the same as those of a secondary lining structure of an operation tunnel.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1: a schematic diagram of a principle of a safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of an operation tunnel;

FIG. 2: schematic diagrams of drilling control depth and part of A-type and B-type;

FIG. 3: a type and B type drilling hole position arrangement principle plane projection schematic diagrams;

FIG. 4: a class drilling grouting principle schematic diagram;

FIG. 5: b-type drilling grouting principle schematic diagram.

Wherein: 1. the method comprises the following steps of (1) soft surrounding rock, 2, a water storage and guide structure, 3, A type drilling, 4, B type drilling, 5, a secondary lining, 6, a water storage and guide structure filling body and 7, wherein the soft surrounding rock is reinforced by grouting.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

A safe and rapid water plugging and reinforcing method in strong water-rich soft surrounding rock of an operation tunnel comprises the following steps:

1. firstly, according to a design scheme for treating water-inrush and mud-inrush geological disasters of a tunnel, a range of mileage pile numbers of the tunnel to be treated is defined in the tunnel. Firstly, marking the hole positions of A-type drill holes on the surface of the second lining 5 in a selected treatment range, and then marking the hole positions of B-type drill holes after the A-type drill holes are constructed.

2. Firstly, constructing A-type drilling holes. The A-type drilling holes 3 are grouting drilling holes for exploring, revealing and plugging the water storage and guide structure 2 in the deep part of the surrounding rock. The A-type drill holes need to penetrate through the two-lining structure 5, the depth of the A-type drill holes exceeds that of the two linings 5 and enters the surrounding rock by 2m, and the depth of the A-type drill holes is 2.5m because the thickness of the two-lining structure 5 is 0.4 m. The bore diameter of the drill hole is phi 150mm, a phi 127mm grouting sleeve is put into the drill hole, and the length b of the phi 127mm sleeve is 2.5 m. And (3) grouting and sealing gaps among the outside of the phi 127mm grouting sleeve pipe, the secondary lining and the surrounding rock, wherein the grouting and sealing pipe is made of cement-based double-liquid slurry. When the casing is sealed by grouting, when the grouting pressure of the drill hole reaches 1.5 times of the designed grouting final pressure, the casing does not move outwards, and when no leakage exists outside the casing, the sealing of the casing is qualified. The final pressure of NSB tunnel disaster control grouting design is 3MPa, and the failure pressure of a water injection test after the sleeve is sealed is 4.5 MPa. And after the casing is sealed and qualified, drilling construction in the surrounding rock by using the hole diameter of 75 mm.

3. The thickness h of the NSB tunnel surrounding rock curtain grouting reinforcing ring is designed₁(i.e., the depth of the B-type drill hole) is 15m, so that the design depth of the A-type drill hole does not exceed 30m at most, namely h₂Is 30m, h₁Is 15 m. The depth of the A-type drill hole is different according to the position of the A-type drill hole and the depth of the water storage and guide structure 2 in the exposed surrounding rock. The A-type drilling can be used for grouting only after the water storage and guide structure 2 is exposed. The grouting requirement is that the disclosed water storage and guide structure 2 is fully filled with grout to stop grouting, and the judgment standard of whether the structure is fully filled or not reaches the designed grouting final pressure or not. The water storage structure 2 is filled with the slurry to form a water storage structure filler 6 with certain strength and water-resisting capability, as shown in fig. 4.

4. The grout used for the A-type drilling grouting is single-liquid cement grout or cement-based double-liquid grout. The single-fluid cement slurry is prepared from P.O 42.5.5R ordinary portland cement produced locally. The density of the cement paste is controlled to be 1.5-1.75g/cm³In the meantime. During the grouting process, the concentration of the cement slurry used at the beginning is 1.5g/cm³About, when the grouting pressure at the initial stage of grouting is lower than 1.0MPa, the density of the used cement paste is 1.75g/cm³About (the density fluctuation is not more than 0.05 g/cm)³) When groutingWhen the pressure is higher than 1.0MPa, the density of the used cement paste is 1.50g/cm³About (the density fluctuation is not more than 0.05 g/cm)³). When the grouting pressure reaches the designed grouting final pressure, intermittent grouting, namely, a mode of grouting-stopping-grouting, is carried out by adopting a minimum pump amount (NBB260/7 grouting pump minimum pump amount is 40L/min), and grouting is stopped until the grouting pressure is continuously kept at about 3.0MPa and the duration is not shorter than 5 minutes.

(2) When the grouting pressure does not rise and is still lower than 0.5MPa after the grouting of the A-type drilling exceeds 60 minutes and the grouting rate is not reduced, the single-liquid cement slurry is changed into the cement-based double-liquid slurry. The cement-based double-liquid slurry used as the auxiliary grouting slurry is cement-water glass slurry, the modulus of the water glass is 2.8, and the baume degree is 38 Be. When preparing the double-liquid cement paste, the average density of the used single-liquid cement paste is 1.60g/cm³Left and right. The volume ratio of the cement paste to the water glass paste is 2:1, and the initial setting time of the mixed paste is about 45 seconds. After the cement-water glass mixed slurry is injected, when the grouting pressure exceeds 50% of the designed final pressure and has a pressure-raising trend, the single-liquid cement slurry is injected again. When the pressure is lower than 1.0MPa, injecting the double-liquid slurry. In this way, the single-fluid cement slurry or the cement-based two-fluid slurry is alternately injected in a repeated manner, and finally, the single-fluid cement slurry is injected as the slurry at the end of the grouting.

5. After the A-type drilling is completely constructed, B-type drilling hole sites are distributed among the A-type drilling hole sites according to the drilling positioning modes shown in the figures 2 and 3, and B-type drilling is constructed. The depth controlled by the type B drilling is the thickness h for grouting reinforcement of surrounding rock curtains at the shallow part of the tunnel₁. The specification and length of the B-type drilling grouting casing pipe, the requirements of sealing and consolidation, the requirements of sealing quality and the diameter of a drill hole entering the surrounding rock are the same as those of the A-type drill hole. The B-type drilling construction is carried out in a forward mode, and the water exposure amount of the B-type drilling is 1-3m³When water gushes or hole collapse occurs in the range of/h, grouting can be carried out when the drilling footage reaches 3m, and the section of 3m is taken as a grouting section. The water inflow of the drill hole is less than 1m³And/h or when the hole wall of the drilled hole is stable and does not collapse or fall, taking the hole as a grouting section every 5 m.

The single-liquid cement slurry is injected into the B-type drilled hole, and the requirements on the single-liquid cement slurry are the same as those of the A-type cement slurryThe requirements for the start of grouting are the same. And when the volume of the single-fluid slurry exceeds 2 times of the volume of the grouting drill hole and the grouting pressure is less than the designed final pressure, the cement-based double-fluid slurry is injected. And cement-water glass slurry is selected for grouting in the B-type drill hole. The modulus of the selected water glass is 2.8, and the Baume degree is 38 Be. When preparing the double-liquid slurry, the qualified P.O42.5R cement is selected as the cement slurry, and the density of the cement slurry is controlled to be 1.55g/cm³The upper and lower floating rate is not more than 0.05g/cm³. The volume ratio of the cement paste to the water glass paste is 1:1 or 2:1, and the initial setting time of the mixed paste is about 90 seconds or 45 seconds. And stopping grouting when the grouting pressure reaches the design final pressure of 3.0MPa and the pressure is continuously increased. The soft surrounding rock 7 is obtained after being reinforced by grouting, as shown in fig. 5.

6. And (5) the technical requirements on the safety of grouting operation.

(1) In both the type a drilling and the type B drilling, the designed grouting final pressure is used as a main reference grouting end standard, and the grouting rate (pump rate) at the designed final pressure is used as an auxiliary reference grouting end standard.

(2) In order to ensure the grouting safety, before the AB two types of drilling holes are used for grouting, the test drilling holes are used for carrying out a safety grouting test. Selecting safe grouting pressure which does not cause serious deformation of surrounding rock during test drilling as grouting ending design pressure, taking the grouting rate (pump capacity) at the moment as auxiliary design grouting ending rate, and taking corresponding slurry preparation parameters as reference parameters selected during grouting.

(3) During grouting of the cement-based double-liquid slurry, the initial setting time of the required cement-based double-liquid slurry is calculated according to parameters such as grouting depth in a drill hole, surrounding rock loosening degree, water inflow amount of the drill hole, test grouting pressure and the like, and then the appropriate injection proportion of the two kinds of slurry is selected on site according to the pump capacity of a grouting pump so as to ensure grouting safety and grouting effect.