CN111519626B

CN111519626B - Sleeve valve pipe reverse grouting method suitable for deep covering layer permanent curtain

Info

Publication number: CN111519626B
Application number: CN202010369806.3A
Authority: CN
Inventors: 宗敦峰; 王晓飞; 郭万红; 孙亮; 赵明华; 石峰; 李文书; 蒋志勇; 付成; 张家俊
Original assignee: Sinohydro Foundation Engineering Co Ltd
Current assignee: Sinohydro Foundation Engineering Co Ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2021-01-12
Anticipated expiration: 2040-04-30
Also published as: CN111519626A

Abstract

The application provides a sleeve valve pipe reverse grouting method suitable for a permanent curtain of a deep covering layer, wherein two-sequence holes of the permanent curtain are grouted by adopting the sleeve valve pipe, and the method comprises the following steps: inserting a blocking plug into a sleeve valve pipe of the current grouting section; opening the ring until the water inflow is stable: injecting water into the grouting pipe to reach an open-loop pressure so as to flush a grout stopping ring and casing materials outside the casing valve pipe and inject water into the stratum; chemical slurry pouring: injecting chemical grout into the grouting pipe at a set pressure; if the pouring pressure suddenly drops or the pouring rate suddenly increases in the chemical grout pouring process, replacing the chemical grout with cement-based material; and (4) replacing the chemical slurry pouring for the cement-based material pouring until the end standard is reached. The application adopts the chemical grouting to form reverse echelon grouting in advance of the reverse grouting sequence of cement substrate grouting in the two-sequence hole grouting, and effectively blocks micro gaps, large gaps and channels in the preliminarily formed water-blocking curtain.

Description

Sleeve valve pipe reverse grouting method suitable for deep covering layer permanent curtain

Technical Field

The application relates to a sleeve valve pipe reverse grouting method suitable for a permanent curtain of a deep covering layer.

Background

The curtain grouting is a grouting engineering which pours grout into cracks and pores of a rock mass or a soil layer to form a continuous waterproof curtain so as to reduce seepage flow and osmotic pressure.

Curtain grouting engineering for constructing an impervious curtain using grouting in a rock or sand gravel foundation of a gate dam. The top of the curtain is connected with a concrete gate bottom plate or a dam body, and the bottom of the curtain penetrates into a certain depth relative to an impervious rock stratum so as to prevent or reduce the permeation of underground water in a foundation; and the lifting pressure of the seepage water flow on the gate dam can be reduced under the combined action of the seepage water flow and a drainage system positioned at the downstream of the seepage water flow.

For the project which has been constructed or grouted with the concrete impervious wall, when the project downstream has water gushing and sand gushing and needs to be supplemented with a curtain, the geological condition of the section to be irrigated is greatly different from the original state of the stratum. In the filling process, because the verticality of the pre-buried pipe left in the previous grouting is often poor, a great amount of pre-buried pipe drilling is difficult to perform; therefore, only one row of grouting holes of new cloth can be relied on during the filling, and therefore, a water-blocking curtain with enough thickness cannot be formed under the condition of a single row of holes by using the conventional grouting method. As the project in the filling is often operated for years, various stratums encountered by the row of holes are treated by the impervious wall and the original curtain grouting under the wall, which is different from the original geological state, so that no method is available for judging the actual conditions of the filled part and the filled body before the grouting. Therefore, the ordinary grouting method cannot meet the grouting requirements of the filling project, and particularly under the conditions of high water head, flowing water, deep covering layer, permanent curtain, grouting control and other high difficulties, the water-blocking curtain formed by the conventional grouting method has poor water-blocking effect and reliability, and the problem of water burst and sand gushing cannot be solved.

During chemical grouting, chemical grout is injected into engineering parts needing to be treated, such as bedrock, covering layers, cracks and the like, by using pressure, so that the engineering parts are filled, diffused, gelled and solidified, and the purposes of seepage prevention, leakage stoppage, reinforcement and the like are achieved; the chemical grouting has the advantages of high pressure, stability and reliability, and can allow chemical grout to completely enter deep micro cracks of a concrete structure, so that the water stop effect is good. The chemical grouting liquid has mature technology and complete varieties, basically realizes the production of single-component finished products, does not need on-site blending, has stable quality and can be used after opening a barrel. The slurry is resistant to chemical corrosion, nontoxic and environment-friendly after being cured, and can be permanently waterproof. In curtain grouting, the conventional grouting method is to fill the first-order hole first and then fill the second-order hole, and the grouting method of the second-order hole is consistent with that of the first-order hole. Chemical grouting of bedrock and overburden in conventional grouting is mostly performed after cement grouting.

Disclosure of Invention

In view of the above-mentioned drawbacks and deficiencies of the prior art, it is desirable to provide a grouting control method suitable for a permanent curtain of a deep cover layer under high difficulty conditions such as high water head, running water conditions, deep cover layer, permanent curtain, grouting control, etc.

In order to solve the technical problem, the invention provides a grouting control method suitable for a permanent curtain of a deep covering layer, wherein a sleeve valve pipe is adopted for grouting a second-order hole, and the grouting control method comprises the following steps:

inserting a blocking plug into a sleeve valve pipe of the current grouting section;

opening the ring until the water inflow is stable: injecting water into the grouting pipe to reach an open-loop pressure so as to flush a grout stopping ring and casing materials outside the casing valve pipe and inject water into the stratum;

chemical slurry pouring: injecting chemical grout into the grouting pipe at a set pressure;

if the chemical grout is not effective in pouring, replacing the chemical grout with a cement-based material; and (4) replacing the chemical slurry pouring for the cement-based material pouring until the end standard is reached.

According to the technical scheme provided by the embodiment of the application, the chemical pulp comprises a first chemical pulp and a second chemical pulp; the viscosity of the first chemical pulp is not more than 30mPa.s, and the setting time range is 20-40 min; the viscosity of the second chemical pulp is not more than 30mPa.s, and the setting time range is 5-15 min; the chemical grout injection specifically comprises:

injecting first chemical grout into the grouting pipe at a set pressure;

and if the first chemical grout is ineffective to pour, replacing the grout liquid from the first chemical grout to the second chemical grout.

According to the technical scheme provided by the embodiment of the application, the first-order hole corresponding to the second-order hole is grouted by adopting a sleeve valve pipe, and the method comprises the following steps:

opening the ring: injecting high-pressure water into the grouting pipe to achieve the open-loop pressure so as to flush the grout stopping ring and the casing material outside the casing valve pipe, and injecting water into the stratum;

inducing and injecting water: after the ring is opened, high-pressure water is continuously injected into the grouting pipe by induced pressure so as to test the permeability of the current irrigated section, and an irrigation channel is formed by the impact of the current irrigated section with higher permeability; the induced pressure P_{Induction of}The following two formulas are satisfied simultaneously:

P_{induction of}≥1.5＊P_{Water head}+P_{Resistance device}－P_{Still water}(formula one);

P_{induction of}≥P_{Water head}+1(MPa)+P_{Resistance device}－P_{Still water}(formula two);

P_{water head}The water head pressure born by the current irrigated section; p_{Is hindered by}Critical resistance of the sleeve valve pipe open loop; p_{Still water}Hydrostatic pressure in the current hole;

when the induction water injection state is judged to reach the induction ending condition, ending the induction water injection;

grouting according to the condition of induced water injection to form a thick waterproof curtain.

According to the technical scheme provided by the embodiment of the application, the induction end condition is as follows:

induction end conditions a: the water injection pressure does not reach the induction pressure, or,

induction end conditions b: the perfusion flow rate is close to or equal to the maximum of the grouting pump, or,

induction end conditions c: the water injection pressure is continuously kept near the induction pressure, and the induction water injection time reaches a set duration; the range of the set duration is more than or equal to 60 min.

According to the technical scheme provided by the embodiment of the application, the concrete grouting according to the induced water injection condition is as follows:

if the induction water injection is finished under the induction finishing condition a or the induction finishing condition b, injecting double-liquid slurry or sulphoaluminate cement-based underwater undispersed paste slurry into the grouting pipe;

if the induced water injection is finished under the induction finishing condition c and the perfusion flow during the induced water injection is larger than the set flow, injecting the portland cement-based underwater undispersed paste slurry into the grouting pipe;

and if the induction water injection is finished under the induction finishing condition c and the perfusion flow during the induction water injection is less than or equal to the set flow, injecting chemical grout materials into the grouting pipe.

According to the technical solution provided by the embodiment of the present application,

if the induction water injection is finished under the induction finishing condition c, and the Portland cement-based underwater undispersed paste grouting or chemical grout material grouting is carried out; if the injection rate in grouting continuously rises and is more than 30L/min; the current grouting liquid is replaced by sulphoaluminate cement-based underwater undispersed paste or double-liquid-slurry high-pressure large-flow continuous injection.

According to the technical scheme provided by the embodiment of the application, the range of the set flow is less than or equal to 80L/min.

According to the technical scheme provided by the embodiment of the application, the double-liquid slurry is prepared from 0.5:1, adding 10-20% of water glass into common cement slurry; the final setting time range of the sulphoaluminate cement-based underwater undispersed paste is 20-60 min.

According to the technical scheme provided by the embodiment of the application, the initial setting time of the non-dispersed paste under the portland cement-based water is not more than 12h, and the final setting time is not more than 18 h.

According to the technical scheme provided by the embodiment of the application, the chemical pulp is environment-friendly acrylate chemical pulp or silica sol.

The invention has the advantages that:

1. in the second-order hole grouting, a reverse grouting sequence that chemical grouting is prior to cement base material grouting is adopted, so that tiny gaps of the stratum can be well filled, and a compact and reliable waterproof curtain is formed together with a primary waterproof curtain formed by the first-order hole; the scheme is preferably used under the conditions that the grouting range of the first-order hole is wide and the grouting strength is high, in the situation, a primary water-blocking curtain is mostly formed around the stratum of the second-order hole, if a common cement-based material preferential grouting method is adopted, the hole wall is blocked by the cement-based material, and the chemical grout cannot be poured into the stratum at all, so that the compactness of the whole water-blocking curtain is influenced even if a subsequent chemical grouting effect is poor, and particularly, in the preferential mode, the first chemical grout with relatively long coagulation time, the second chemical grout with relatively short coagulation time and the cement-based material are adopted to block the micro gaps and the channels, and the compactness, the strength, the reliability and the permanence of the whole water-blocking curtain are improved;

simultaneously, the preferable scheme of the application also has the following advantages:

1. the requirements of grouting projects with complex and unknown geological conditions are met, for example, the construction process of an early impervious wall and a curtain under the wall greatly influences the in-situ layer; when the water-saving type water-saving irrigation system runs under a high water head for many years, the durability of walls and curtains is problematic, but the geological condition during the filling is not clear, so that the complicated and high-difficulty engineering environment is formed; the application overturns the conventional operation of the conventional grouting engineering, and adopts an induced water injection method, namely, a high induced pressure impacts a grouted section for a long time, so that the current geological environment is tested, and a grouting channel is opened; no matter what the current stratum is, adopting high-pressure water to induce for more than 1 hour, if the current stratum can bear long-time high-pressure water impact, then detecting that the peripheral irrigated stratum of the irrigated section is quite compact and has low permeability, and the stratum is easy to irrigate when the stratum is relieved after long-term operation; on the contrary, if the fracture occurs under high-pressure water injection, the current stratum permeability is high, and a large injection channel can be formed by opening the fracture; the perfusion channel needs to be perfused and blocked during perfusion; therefore, the high-pressure induced water injection realizes the rapid homogenization of the filled stratum after the compactness and permeability of the stratum are checked, a cushion is made for the subsequent grouting, and the grouting effect and efficiency can be greatly improved; thereby forming an effective permanent water-blocking curtain; the overall grouting effect is inspected, and the actual linkage with the engineering is good; and the induction pressure can be adjusted according to the actual operation condition of the irrigated section, so that the method is convenient to popularize and apply.

2. Forming a curtain with enough thickness under the condition of a single row of holes, and according to the conventional grouting method, the waterproof curtain with enough thickness can be realized by more than 3 rows of grouting holes; in the scheme, a large pouring channel is formed in the induced water injection, so that a thick waterproof curtain is correspondingly formed during the grouting; and the longer the time of induced water injection is, the thicker grouting curtain can be formed, the higher the stratum compactness is, and the running safety of the grouting curtain is ensured.

3. Repeated grouting can be performed; as the sleeve valve pipe is adopted for grouting in the application, all grouting is finished, after the operation is carried out for a period of time (such as several years), if abnormal operation monitoring is found, the induction grouting can be carried out again through the embedded sleeve valve pipe, and the induction pressure used at the moment is higher than that used in the first grouting; the induction method is used for reinforcement, the operation monitoring data can be processed at the first time after the abnormality is found, and the method is very favorable for long-term, safe and stable operation of the whole dam.

In conclusion, the induced grouting method is adopted in the application, and the requirements of analyzing geological conditions, opening a grouting channel, guiding to select grouting materials and ensuring long-term safe and stable operation of the dam are met;

the reverse grout in two preface holes combines with the induced grout in one preface hole in this application, has not only improved grout efficiency, has still improved the reliability and the intensity of the permanent curtain grout in deep overburden layer.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

FIGS. 1 and 2 are schematic structural views of a sleeve assembly of the present application;

FIG. 3 is a schematic view of the structural principle of the casing grouting in the present application;

FIG. 4 is a flow chart illustrating grouting of a hole in the present application;

FIG. 5 is a flow chart illustrating grouting of a second-order hole according to the present application;

reference numbers in the figures: 2. a grout stopping ring; 3. a connecting socket; 21. a slurry outlet; 22. an elastic band; 10. a sleeve valve base pipe; 11. a bottom sleeve valve tube; 12. a common valve sleeve; 5. an expansion plug; 6. Grouting pipes; 7. sheathing a shell material; 8. an earth formation; 23. and (7) fixing the belt.

Detailed Description

The present application will be described in further detail with reference to the following drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the relevant invention and not restrictive of the invention. It should be noted that, for convenience of description, only the portions related to the present invention are shown in the drawings.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

In the following, this example illustrates the detailed process of the scheme of the present application in the following items:

a hydropower station stores water, the elevation of the dam crest is 1385m, the elevation of normal water storage is about 1375m, and the water and sand gushing condition occurs at the downstream, so the curtain filling is needed, and the grouting curtain needs enough thickness to ensure the durability of the curtain; normally, the coating reinforcement should be applied at the top of the dam. However, this cannot be done in practice. The dam seepage-proofing structure comprises galleries to cause separation between dam seepage-proofing and dam foundation seepage-proofing, and the cover layer is about 1156m at the deepest part and is required to be drilled and grouted about 230m when being implemented from the dam top, so that the requirements cannot be met by the current technical capability. Therefore, the implementation of the filling in the grouting gallery is the only feasible scheme, but the height of the bottom plate of the grouting gallery is 1311m, and the borne water head is 60-70 m; about 155 meters of irrigation needs to be drilled from the corridor. Such high heads and such deep drill-down depths are both higher and deeper than typical drapery-down drills.

Significant changes have occurred in the geological conditions and reports at the time of replenishment at hydropower stations a. Because the construction of the concrete impervious wall is already carried out above 1200 m. Although the diaphragm wall is not arranged below 1200m, the diaphragm wall is grouted, and the diaphragm wall is different from the original state of the stratum. The A hydropower station is provided with three rows of holes, two rows in the wall and one row at the downstream. From the implementation, because two rows of holes in the wall are implemented in the embedded pipe, the verticality of the embedded pipe is not good, and quite a plurality of embedded pipe drilling holes are difficult to perform. Therefore, in practice, drilling is completely reliant on only one row, i.e., a newly-placed row of grouting holes on the downstream side of the diaphragm wall.

The downstream drainage and grouting holes have the following characteristics: firstly, the vertical direction is through, the corridor bottom plate can completely penetrate a covering layer of 155m to 1156m from 1311m, the corridor bottom plate can continuously drill to a relative impermeable bed of bedrock from the interior of the pipe after a valve sleeve is arranged below the corridor bottom plate, full-hole full-section grouting is realized, two rows of walls are performed in a pre-buried pipe, grouting can be performed only under the wall (1200m), and no effect is caused on 111m between 1200 sand-doped walls 1311; secondly, various stratums encountered by the drainage hole are treated by the impervious wall and the original curtain grouting under the wall, which is different from the original geological state, so that the actual conditions of a grouted part and a grouted body cannot be judged before grouting, and a grouting scheme capable of obtaining satisfactory effect under any geological conditions is needed.

For the drilling condition, grouting by using an orifice sealing method is adopted during primary drilling, and the failure is ended, so that the severe environment is not suitable for grouting by using the orifice sealing method; because: firstly, the orifice sealing method is full-hole compression, and accurate grouting cannot be performed for a specific section, so that the effect is poor; secondly, the hole opening sealing method needs too large repeated hole sweeping engineering amount, particularly a deep hole section with the depth of more than 100m, the hole is often swept and deviated due to the fact that water stones in the original hole are more complete than the stratum of the hole wall, and the drilling efficiency is greatly influenced; third, the common grouting method has poor power resistance and longer gelation time, so the retention rate is very low, the performance after consolidation is very poor, and the cement is finally and completely destroyed under the continuous flushing of power water.

According to the technical specification of the hydropower and hydraulic engineering covering layer grouting, each row of grouting holes can be divided into a first-order hole and a second-order hole, the second-order hole is positioned between the first-order holes, and the first-order holes are preferentially poured; in this embodiment, the grouting method of the first-order hole and the second-order hole will be described in order.

In this embodiment, the first-order hole and the second-order hole are both grouted by using a valve casing pipe, and the valve casing pipe assembly optionally adopts the following structure: as shown in fig. 1: the slurry stopping device is composed of a plurality of connected sleeve valve pipes, wherein the slurry stopping rings 2 are arranged on the plurality of connected sleeve valve pipes at intervals of a preset distance, in the concrete implementation, the preset distance between the adjacent slurry stopping rings 2 is 300-350 mm, and the preset distance can be adjusted according to the actual engineering. Many cover valve pipes comprise bottom cover valve pipe 11 and several ordinary cover valve pipes 12 of connection in bottom cover valve pipe 11 top that are used for settling at the deep overburden hole bottom, and bottom cover valve pipe 11 and ordinary cover valve pipe 12 include: a sleeve valve base pipe 10; a grout stopping ring 2 arranged on the base pipe 10 of the sleeve valve; wherein, the bottom valve sleeve 11, the common valve sleeve 12 positioned above the bottom valve sleeve and the common valve sleeve 12 are welded together through the connecting socket 3.

As shown in fig. 1, the bottom end structure of the base sleeve pipe 10 of the bottom sleeve pipe 11 is a closed structure. As shown in fig. 2, each stop collar 2 on the bottom sleeve 11 comprises: the plurality of grout outlet holes 21 are circumferentially arranged along the sleeve valve base pipe 10, during specific implementation, 3-5 grout outlet holes 21 are generally formed, the probability that the grout outlet holes are blocked in the grouting process can be greatly reduced through the plurality of grout outlet holes, and subsequent open-loop and grouting construction can be effectively guaranteed to be smoothly carried out; an elastic hoop 22 wrapping the plurality of grout outlet holes 21; and the fixing belts 23 are wound on the upper end and the lower end of the elastic hoop 22 and fix the elastic hoop 22 on the base pipe 10 of the sleeve valve and are used for preventing the elastic hoop 22 from sliding off in the process of arranging the sleeve valve below the sleeve valve.

The diameter of the elastic hoop 22 is 1-3 mm smaller than that of the base pipe 10 of the sleeve valve, so that the elastic hoop 22 can be wrapped on the base pipe 10 of the sleeve valve. During specific construction, the elastic hoop 22 is a rubber hoop with proper elasticity, so that ring-opening grouting can be ensured under certain pressure, and the phenomenon that the grouting stop function is lost or the rubber hoop cannot be reused due to damage under the action of pressure can be avoided.

Specifically, the material and the pore size of the ordinary sleeve valve pipe 12 and the sleeve valve base pipe of the bottom sleeve valve pipe 11 are selected to be consistent. The structure of the grout stop ring 2 manufactured on the base pipe 10 of the common sleeve valve pipe 12 is also the same as the structure of the grout stop ring 2 manufactured on the base pipe of the bottom sleeve valve pipe 11, and the detailed description is omitted.

In this example, the valve sleeve and the jacket material were formed in the following manner: in the drilling process, when the hole is drilled to the bottom of the hole, the weighted wall protection slurry in the drilling process is switched into a casing material, and the casing material is ejected out of the weighted wall protection slurry in the hole after being injected, so that the casing material is fully injected into the whole hole; casing materials are supplemented at any time in the process of pulling out the drill; then a sleeve valve pipe is arranged below the lower part.

In other embodiments, pneumatic down-the-hole casing pipe-following drilling techniques may also be employed:

follow the pipe and creep into and accomplish with the lower cover valve pipe assembly after, will irritate two stopper cards of material to cover valve pipe assembly bottom, irritate two stopper of material and include: two expansion plugs; and the injection port is positioned between the two expansion plugs and is connected with the grouting pipe. A grout stopping ring at the bottom of the sleeve valve pipe assembly is positioned between two expansion plugs of the grouting double plugs, sleeve slurry is injected from a filling port positioned between the two expansion plugs, and the sleeve slurry forces one grout stopping ring at the bottom of the sleeve valve pipe assembly to open a ring under the action of high pressure and is injected into an annular gap between a heel pipe and the sleeve valve pipe assembly from a grout outlet of the grout stopping ring;

when casing slurry is ejected from a slurry stop ring at the bottom of the casing valve pipe assembly and rises to a certain height in an annular gap between the heel pipe and the casing valve pipe assembly, the grouting double plug is clamped to the middle of the casing valve pipe assembly, one slurry stop ring in the middle of the casing valve pipe assembly is positioned between two expansion plugs of the grouting double plug, casing slurry is injected from a filling port positioned between the two expansion plugs, the casing slurry is forced to open a slurry stop ring in the middle of the casing valve pipe assembly under the action of high pressure, and the casing slurry is ejected into the annular gap between the heel pipe and the casing valve pipe assembly from a slurry outlet hole of the slurry stop ring;

the key point of the valve casing method is that the valve casing method is arranged below, the existing engineering examples almost adopt a pneumatic down-the-hole casing pipe following drilling technology, 89mm valve casing pipes are arranged below 146mm casing pipes after the 146mm casing pipes are arranged at the bottom of a hole, then the method of injecting casing materials and simultaneously drawing out the 146mm casing pipes is adopted, the depth of the valve casing pipes is more than 70m level, and the deepest depth is not more than 100 m. It is worth noting that the 146mm casing pipe in engineering practice is mostly 6m (can be customized or cut, but the cost is high), the requirement of the pneumatic down-the-hole on the field is high, and the narrow field cannot be adopted. However, in the projects listed in this embodiment, the space in the gallery is narrow, and therefore, the pneumatic down-the-hole casing pipe-following drilling technology cannot be implemented.

The schematic diagram of the casing valve pipe grouting is shown in fig. 3, and after drilling and casing valve pipe running are completed, the drill hole is shown in fig. 3; during the pouring, at current grout section, go into the card stopper under the sleeve valve intraductal, as shown in fig. 2, in this embodiment, the card stopper is for irritating material double plug, and it includes to irritate the material double plug: two expansion plugs 5; the injection port is positioned between the two expansion plugs and is connected with the grouting pipe 6; the double plugs are clamped at the upper and lower positions of the grout outlet 21 of the sleeve valve base pipe 10 and correspond to the grout outlet 21 of the current ring; the base pipe 10 of the sleeve valve is sequentially provided with a sleeve material 7 and a stratum 8.

Fig. 4 shows a grouting method for a first-order hole in the present embodiment, which specifically includes the following steps:

it should be noted that the common steps of drilling, injecting casing material, and inserting casing pipe and grouting need to be performed before the following steps are performed, and as described above, the description is omitted here.

s1, inserting a plug into the sleeve valve pipe of the current grouting section; in the embodiment, the blocking plug is a grouting double plug, so that a grout stopping ring in the middle of the sleeve valve pipe is positioned between two expansion plugs of the grouting double plug.

s2, open loop: injecting high-pressure water into the grouting pipe to achieve the open-loop pressure so as to flush the grout stopping ring and the casing material outside the casing valve pipe, and injecting water into the stratum; in this example, the ring-opening pressure is 3MPa to 6 MPa; after the high-pressure water breaks through the stratum, the high-pressure water enters the stratum along the arrow direction in the figure 3;

s3, induced water injection: and after the ring is opened, high-pressure water is continuously injected into the grouting pipe by induced pressure so as to check the permeability of the current irrigated section, and an irrigation channel is formed by the impact of the irrigated section with higher permeability. The induced pressure P_{Induction of}The following two formulas are satisfied simultaneously:

wherein P is_{Water head}Elevation of dam reservoir (m) -elevation of irrigation section (m)]The elevation of the irrigated section is the average elevation of the current irrigated section, for example, the length of the current irrigated section is 1.2 meters, the elevation of the current irrigated section is 1156-1157.2 from bottom to top, and the elevation of the current irrigated section is the average value 1156.6; dam impoundment elevation is 1375m, so the P of the current irrigated section_{Water head}＝(1375－1156.6)/100＝2.184MPa；

Wherein P is_{Resistance device}The critical resistance value of the sleeve valve pipe open loop is 0.2 MPa-0.5 MPa after the sleeve valve pipe open loop is given a pressure value to generate water injection flow, and the critical resistance value is 0.2 MPa-0.5 MPa through field tests_{Resistance device}Taking 0.35 MPa;

wherein P is_{Still water}[ elevation of hole (m) — elevation of irrigation section (m)]100; for example, the current irrigated segment is 1156-1157.2, then P_{Hydrostatic pressure}＝(1311－1156.6)/100＝1.544MPa；

The three values of the current irrigation section are respectively shown in the following table 1:

TABLE 1

1.5＊P_{Water head}+P_{Resistance device}－P_{Still water}	P_{Water head}+1+P_{Resistance device}－P_{Still water}
		2.082MPa	1.99MPa

Then the induced pressure should be P_{Induction of}More than or equal to 2.082 MPa; the induction pressure can be read from a pressure gauge on the grouting pump, so that the reading of the pressure gauge on the grouting pump is more than or equal to 2.082MPa when the induction pressure is given.

Exceeding the critical pressure P during grouting of the overburden_{Critical point of}And maintaining for a certain time to generate cleavage, critical pressure P_{Critical point of}Namely the pressure when the splitting is also the pressure when the perfusion coefficient is suddenly changed, wherein the perfusion coefficient is the ratio of the perfusion flow to the perfusion pressure; therefore, the practice of injecting water into the covering layer for a long time at a pressure exceeding the critical pressure is generally prohibited in the conventional engineering; in the technical scheme of the application, the limitation is broken through: the reason that the permeability change is large in a short distance due to poor geological condition uniformity of a complex stratum and the conventional grouting method has poor effect in the situation is that the geology with high permeability cannot withstand high flowing water impact, so that water gushing and sand gushing can occur after the grouting method is operated for a period of time; in the scheme, by setting the induction pressure to meet the two formulas, the water injection pressure is properly increased to a certain pressure value higher than the water head pressure of the induction pressure, the critical pressure of the stratum with high permeability can be broken through, and a grouting channel is opened in the stratum, so that the stratum can be homogenized through grouting; meanwhile, if no splitting occurs under the induction pressure, the stratum is detected to be a compact covering layer within a certain range, and the long-term operation is facilitated.

This application is not directed to P_{Induction of}Is limited, but those skilled in the art will recognize that P is a limiting factor_{Induction of}The scale cannot be increased arbitrarily, and the aim of breaking through a stratum with high permeability and homogenizing the stratum through grouting is to properly adjust the upper limit value of the formula according to the actual geological condition of the engineering and the drilling and grouting depth on the basis of meeting the lower limit value of the formula, wherein P is based on the scheme of the application_{Induction of}Should be within 1MPa of its lower limit.

And when the water injection pressure does not reach the induction pressure or the injection flow is close to or equal to the maximum value of the grouting pump, the permeability is high, and the injection channel can be formed by impact.

In this example, the induction pressure was 3 MPa; on the premise that the pressure does not generate mutation, the duration of the induced pressure is not shorter than 1 hour; therefore, the method can be used for testing regardless of the geological conditions of the current stratum, if the permeability of the current stratum is higher, splitting can occur under the impact of high-pressure water, so that the pressure cannot be kept or the perfusion flow rate is increased, and a large grouting channel is inevitably formed under the impact of the stratum; if the current stratum has small permeability, the pressure of high-pressure water injection can be maintained, the current stratum has small permeability through inspection, and long-term safe operation can be ensured through simple perfusion.

s4, when judging that the induction water injection state reaches the induction end condition, ending the induction water injection;

the induction end conditions are as follows:

induction end conditions c: the water injection pressure is continuously kept near the induction pressure, and the induction water injection time reaches a set duration;

in the process of inducing water injection, the inducing pressure is used as the initial water injection pressure of the grouting pump, and the value of the water injection pressure can be read by a pressure gauge arranged on a grouting pipeline; the pouring flow rate is obtained by a flowmeter arranged on the grouting pipeline; when the water injection pressure does not reach the induction pressure or the injection flow is close to or equal to the maximum value of the grouting pump, the current grouting stratum is the weakest part at the periphery of the grouting section, the permeability is high, the rapid homogenization of the grouting stratum can be realized by the high-pressure water injection or the high-flow water injection, a grouting channel is flushed at the part, and a water-blocking curtain with enough thickness can be formed by grouting in the grouting channel; in this embodiment, the waterproof curtain formed by the single row of grouting holes is equal to the thickness of the waterproof curtain formed by the three rows of grouting holes in the normal grouting. The length of the induction time is directly related to the thickness of the formed grouting curtain, and the thicker the induction time is, the thicker the grouting curtain can be formed.

In the process of inducing water injection, the set duration is greater than or equal to 60min, and in this embodiment, the set duration is 60-120 min; that is, if the current grouted section can withstand the impact of high-pressure water for a long time, the grouted stratum around the grouted section is quite compact, and the grouting section is more reliable in long-term operation.

s5, grouting according to the induction water injection condition; the method specifically comprises the following steps:

if the induction water injection is finished under the induction finishing condition a or the induction finishing condition b, injecting double-liquid slurry or sulphoaluminate cement-based underwater undispersed paste slurry into the grouting pipe; when the water injection pressure does not reach the induction pressure or the injection flow is close to or equal to the maximum value of the grouting pump, the current grouting stratum is the weakest part at the periphery of the grouting section, the high-pressure water injection or the high-flow water injection can realize the rapid homogenization of the grouted stratum, and a grouting channel is flushed at the part; therefore, double-liquid slurry or sulphoaluminate cement-based underwater undispersed paste slurry needs to be injected into the flushed grouting channel for grouting, and the channel is rapidly plugged;

in this example, the biliquid slurry is prepared from 0.5:1 common cement slurry is mixed with 10-20% water glass. The sulphoaluminate cement-based underwater undispersed paste slurry is prepared by adding an additive into a composite grouting material serving as a base material. The composite grouting material is prepared by adding additives into sulphoaluminate cement serving as a base material, wherein the additives can be boric acid, lithium carbonate, polyacrylamide, cellulose ether and the like; in this embodiment, the final setting time of the sulphoaluminate cement-based underwater undispersed paste slurry is in the range of 20min to 60 min; preferably the 3d (after 3 days of construction) compressive strength is above 7 MPa; in other embodiments, the sulphoaluminate cement-based underwater grouting liquid which does not disperse paste can also be selected from other grouting liquid which meets the conditions and can quickly coagulate and block the channel material and match.

In the embodiment, double-liquid-slurry grouting is adopted at the end of the induction end condition a or the induction end condition b, and grouting is ended when the grouting pressure reaches the preset pressure of 3.5 MPa-4 MPa and the grouting flow is less than 5L/min. In different projects, the criteria for ending the predetermined pressure and perfusion flow may be determined according to the project situation.

If the induced water injection is finished under the induction finishing condition c and the perfusion flow during the induced water injection is larger than the set flow, injecting the portland cement-based underwater undispersed paste slurry into the grouting pipe; setting the flow rate based on the constant flow rate, wherein if the filled section is a compact covering layer, the filling flow rate is basically constant under the constant filling pressure, and the filling flow rate at the moment is defined as the constant flow rate; when the perfusion pressure needs to be maintained by improving the perfusion flow, the compaction degree of the perfusion section is slightly poor, so that a grouting material suitable for the stratum characteristic needs to be adopted; in a general grouting project, the set flow is set according to the actual condition of the project, on one hand, the set flow is according to the grout sucking condition of the stratum, on the other hand, the set flow depends on the performance of a grouting pump, and the range of the common set flow is less than or equal to 80L/min; in the present embodiment, the flow rate is set to 30L/min; therefore, under the condition of keeping the induction pressure, if the pouring flow rate is increased to 30L/min, the portland cement-based cement paste is poured into the grouting pipe without dispersing; in this embodiment, the initial setting time of the non-dispersed slurry under the portland cement-based water is not more than 12h, the final setting time is not more than 18h, and the preferred compressive strengths of 3d and 28d reach 5MPa and 10MPa respectively.

In the embodiment, when the portland cement-based underwater undispersed paste slurry is poured, the grouting is finished when the grouting pressure reaches the preset pressure of 3.5-4 MPa and the pouring flow is less than 2L/min. In different projects, the criteria for ending the predetermined pressure and perfusion flow may be determined according to the project situation.

In the pouring process of adopting the sulphoaluminate cement-based underwater undispersed paste slurry: if the situation of eating a large amount of pulp occurs, the appearance of eating a large amount of pulp is as follows: the injection rate continuously rises and is more than 30L/min; the sulphoaluminate cement-based underwater undispersed paste or cement-water glass double liquid and other materials are adopted for high-pressure large-flow continuous injection; when a large amount of slurry is eaten, the current stratum has an enlarged grouting channel, so that materials such as sulphoaluminate cement-based underwater undispersed paste slurry or cement-water-glass double liquid are required to be injected continuously at high pressure and large flow, and the channel is blocked.

And if the induction water injection is finished under the induction finishing condition c and the perfusion flow during the induction water injection is less than or equal to the set flow, injecting a chemical slurry material into the grouting pipe for perfusion. As mentioned above, in the process of inducing water injection, the injection pressure and the injection flow rate can be kept near the constant flow rate value and kept above 60 min-120 min, which indicates that the current injection section is compact, and the fine physical characteristics and better permeability of the chemical pulp can be well utilized to permeate into the tiny gaps of the injection section through the injection of the chemical pulp material.

The chemical pulp is environment-friendly acrylate chemical pulp or silica sol; in this example, acrylate chemical pulp is a series product XGELACRYL SR from De Neef, Belgium; in other embodiments, other environmentally friendly chemical grouting materials with low viscosity, high permeability, and high durability may also be used. In the process of pouring by using chemical grout: if the situation of eating a large amount of pulp occurs, the appearance of eating a large amount of pulp is as follows: the injection rate continuously rises and is more than 30L/min; the sulphoaluminate cement-based underwater undispersed paste or cement-water glass double liquid and other materials are adopted for high-pressure large-flow continuous injection; when a large amount of slurry is eaten, the current stratum has an enlarged grouting channel, so that materials such as sulphoaluminate cement-based underwater undispersed paste slurry or cement-water-glass double liquid are required to be injected continuously at high pressure and large flow, and the channel is blocked.

In the embodiment, when the chemical grout is poured, the grouting is finished when the grouting pressure reaches the preset pressure of 1.5 MPa-2 MPa, the pouring flow is less than 1L/min, and the duration is more than or equal to 10 min. In different projects, the criteria for determining the end of the predetermined pressure, perfusion flow rate and duration, etc. may be determined according to the situation of the project.

s6, checking; after grouting is finished, selecting to carry out inspection at a proper time according to the properties of grouting materials and the records of field construction, and the inspection is carried out for several days to several months; in the embodiment, original hole inspection and new hole opening inspection can be adopted for inspection, namely, after the original grouting hole is used for hole sweeping, a sleeve valve pipe does not need to be arranged below the original grouting hole, and injection can be carried out under the pressure of 3 MPa; the valve sleeve is required to be arranged under the drill hole again for the new hole opening detection, and the 3MPa pressure injection is also adopted; and (3) an induction method is adopted for inspection, and the stratum at the position can be preliminarily judged to basically meet the operation requirement from the operation angle as long as the 3MPa can be maintained.

As the sleeve valve pipe is adopted for grouting in the application, all grouting is finished, after the operation is carried out for a period of time (such as several years), if abnormal operation monitoring is found, the induction grouting can be carried out again through the embedded sleeve valve pipe, and the induction pressure used at the moment is higher than that used in the first grouting; the induction method is used for reinforcement, the operation monitoring data can be processed at the first time after the abnormality is found, and the method is very favorable for long-term, safe and stable operation of the whole dam.

In addition, the induced grouting method can also select proper grouting materials according to the induced water injection condition, namely according to the geological conditions of different grouting sections; the operation is very simple and feasible.

And the induced grouting method is adopted to meet the requirements of three aspects of geological condition analysis, grouting channel opening and grouting material selection guidance. Grouting under high water head and flowing water conditions, deep covering layers, permanent curtains, grouting control and other high difficulty conditions is realized.

Fig. 5 shows a grouting method for the second-order hole in the present embodiment, which includes the following steps: it should be noted that the common steps of drilling, injecting casing material, and inserting casing pipe and grouting need to be performed before the following steps are performed, and as described above, the description is omitted here.

sa. setting a plug in the sleeve valve pipe of the current grouting section; this is the same as step s1 described above and will not be described in detail here.

sb. ring opening until the water inflow stabilizes: injecting high-pressure water into the grouting pipe to achieve the open-loop pressure so as to flush the grout stopping ring and the casing material outside the casing valve pipe, and injecting water into the stratum; in this example, the ring opening is from 3MPa to 6 MPa; the stable inflow water can be read out through the reading displayed on the recorder by the flow sensor on the water inlet pipeline, if the numerical value displayed by the flow sensor is near a certain value, the stable inflow water is represented, and the stable inflow water is represented within the variation of 1L/min; if the ring opening pressure is unstable, the ring opening pressure can be properly increased, and the stable water inlet of the complete ring opening is ensured;

sc. chemical pulp pouring: injecting chemical grout into the grouting pipe at a set pressure; in the present embodiment, the set pressure is the perfusion pressure 3MPA, and the chemical pulp includes a first chemical pulp and a second chemical pulp; the viscosity of the first chemical pulp is not more than 30mPa.s (millipascal seconds), and the setting time range is 20-40 min; the viscosity of the second chemical pulp is not more than 30mPa.s, and the setting time is 5-15 min; the chemical grout injection specifically comprises the following steps:

sc1, injecting a first chemical grout into the grouting pipe at a set pressure, wherein the first chemical grout is XGELACRYL SR series product of De Neef corporation, Belgium with the setting time of about 30 min; if the filling flow rate is gradually decreased while the filling pressure is maintained during the process of filling the first chemical grout, it means that the filled section has only a tiny gap, the first chemical grout can be continuously filled for more than 30min until the end, and the end criteria are, for example: when the grouting pressure reaches the preset pressure of 1.5-2 MPa, the grouting flow is less than 1L/min and lasts for more than or equal to 10 min;

if the first chemical pulp is judged to be ineffective in the filling process of the first chemical pulp, replacing the first chemical pulp with a second chemical pulp; and judging that the first chemical grout is ineffective when the following conditions are met: the first chemical grout injection amount reaches a set amount, for example 500L or the pouring time has reached 30min, while neither the grouting pressure nor the injection rate is changed or the change is insignificant, or when the injection rate is greater than 30L/min, or when the pouring pressure suddenly increases by more than 3 MPA;

replacing the first chemical pulp with a second chemical pulp; in this embodiment, the second chemical pulp is a XGELACRYL SR series product liquid of De Neef corporation, belgium, with a setting time of about 10 min;

if the perfusion flow rate is gradually reduced under the condition of keeping the perfusion pressure in the process of perfusing the second chemical pulp, the second chemical pulp can be continuously perfused for more than 30min until the perfusion is finished, and the perfusion finishing standard of the second chemical pulp is the same as that of the first chemical pulp; if the second chemical grout is judged to be ineffective in the pouring process of the second chemical grout, the step sd of replacing the second chemical grout with the cement-based material is executed; and judging that the second chemical grout is not effective when the following conditions are reached: when the grouting pressure and the injection rate are not changed or are not changed significantly, or when the injection rate is more than 30L/min, or when the sudden increase of the grouting pressure is more than 3MPA, the grouting amount of the second chemical grout reaches the set amount of 500L or the grouting time reaches 30 min;

sd. replacing the grouting liquid with cement-based material from the second chemical grout; the cementitious material may be, for example, a sulphoaluminate cement-based underwater non-dispersing paste; and replacing the cement-based material pouring with the first chemical slurry pouring when the cement-based material pouring is close to the end standard. The end criterion is, for example, that the injection rate reaches about 3L/min under the condition of keeping the injection pressure, and the injection is continued for 20min, then the first chemical grout injection is changed, and the end criterion of the first chemical grout injection is the same as the above. Replacement back to the first chemical grout pour can resolve the micro-channels while displacing the cement-based material out of the double plug to prevent casting the plug.

The existing two-sequence holes are filled in the same-sequence hole in the same way, the cement-based materials are directly filled after ring opening, then the cement-based materials are used for gradual slurry changing to reach the design pressure, and the filling is finished until the standard is finished. In the embodiment, the second-order hole is reversely grouted, namely, the second-order hole is firstly grouted with the first chemical grout with relatively long coagulation time if the second-order hole is stably filled with water after being opened by clear water, the second chemical grout with relatively short coagulation time is replaced if the first chemical grout is not grouted, and the cement-based material is then grouted when the second chemical grout is not effective to form reverse gradient grouting; when the cement-based material is close to the end standard, the first chemical slurry is changed back, the grouting is finished, and if necessary, the grouting is finished by using a second chemical slurry. The reason for this is that the formation is homogenized to a certain extent after the first-order hole induction grouting is finished, the second-order hole is reinforced on the basis of the first-order hole, but large leakage slurry still exists in the extremely individual hole sections, and the overall effect is improved by adopting a method of alternately and repeatedly using chemical slurry and cement base material slurry. The reverse grouting is to preferentially adopt chemical grouting materials to solve the tiny leakage channel which the cement-based slurry cannot enter, if the tiny leakage channel is solved by adopting the chemical grouting materials subsequently according to the conventional thinking and methods, the hole wall is blocked by the cement-based slurry, and the chemical slurry cannot be grouted into the stratum at all.

Therefore, by adopting the method of alternately and repeatedly using the chemical grout and the grouting liquid of the cement base material, the tiny gaps, the large gaps and the passages in the water-blocking curtain and the permanent curtain are effectively blocked, and the induced grouting of the first-order hole and the reverse grouting of the second-order hole are combined in the embodiment, so that the dense, high-strength, durable and reliable water-blocking curtain is formed, and the overall effect is improved.

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of the invention as referred to in the present application is not limited to the embodiments with a specific combination of the above-mentioned features, but also covers other embodiments with any combination of the above-mentioned features or their equivalents without departing from the inventive concept. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims

1. A sleeve valve pipe reverse grouting method suitable for a permanent curtain of a deep covering layer is provided, wherein a second-order hole is grouted by adopting a sleeve valve pipe, and the method comprises the following steps:

if the chemical grout is not effective in pouring, replacing the chemical grout with a cement-based material; the cement-based material is poured until the end standard is reached, and then chemical slurry pouring is carried out;

the chemical pulp comprises a first chemical pulp and a second chemical pulp; the viscosity of the first chemical pulp is not more than 30mPa.s, and the setting time range is 20-40 min; the viscosity of the second chemical pulp is not more than 30mPa.s, and the setting time range is 5-15 min;

the chemical grout injection specifically comprises:

injecting first chemical grout into the grouting pipe at a set pressure;

if the first chemical grout is not effective in pouring, replacing the grout liquid from the first chemical grout to the second chemical grout;

the method is characterized in that: and a first-order hole corresponding to the second-order hole is grouted by adopting a sleeve valve pipe, and the method comprises the following steps:

P_{induction of}≥1.5*P_{Water head}+P_{Resistance device}-P_{Still water}(formula one);

P_{induction of}≥P_{Water head}+1(MPa)+P_{Resistance device}-P_{Still water}(formula two);

wherein P is_{Water head}The water head pressure born by the current irrigated section; p_{Resistance device}Critical resistance of the sleeve valve pipe open loop; p_{Still water}The hydrostatic pressure in the current hole is used;

2. The method of reverse grouting of a sleeve valve pipe for a permanent curtain of a deep blanket according to claim 1, wherein the induction end condition is:

induction end conditions b: the perfusion flow rate is equal to the maximum of the grouting pump, or,

3. The method for reverse grouting of a sleeve valve pipe suitable for a permanent curtain of a deep covering layer according to claim 2, wherein grouting according to induced water injection condition is specifically:

4. The method of reverse grouting of a sleeve valve pipe for a permanent curtain of a deep blanket according to claim 3,

5. The method of reverse grouting of a sleeve valve pipe for a permanent curtain of a deep blanket according to claim 4, wherein the set flow rate is in a range of 80L/min or less.

6. The method for reverse grouting of a sleeve valve pipe suitable for a permanent curtain of a deep covering layer according to claim 4, wherein the two-fluid slurry is composed of 0.5:1 common cement slurry with 10-20% water glass by volume; the final setting time of the sulphoaluminate cement-based underwater undispersed paste is 20-60 min.

7. The method of reverse grouting of a sleeve valve pipe for a permanent curtain of a deep overburden layer as recited in claim 6, wherein a final setting time of said portland cement-based underwater nondispersed paste ranges from 20min to 60 min.

8. The method for reverse grouting of a sleeve valve pipe suitable for a permanent curtain of a deep coverage layer according to claim 1, wherein the chemical grout is environmental-friendly acrylate chemical grout or silica sol.