CN115506316B - Concrete backfilling method for sealed space leakage vertical shaft under high external water pressure - Google Patents

Abstract

The invention discloses a concrete backfilling method for a sealed space leakage vertical shaft under high external water pressure, relates to the field of hydraulic and hydroelectric engineering, and solves the problem that a large amount of leakage water in the vertical shaft has adverse effects on steel lining installation and backfilling concrete pouring. The technical scheme adopted by the invention is as follows: the method for backfilling the concrete in the sealed space leakage vertical shaft under high external water pressure adopts a measure of combining blocking and draining, so that leakage water is dredged orderly, and adverse effects of the action of water on steel lining welding and backfilling concrete are avoided. Adopting pre-buried water-blocking drainage facilities and adopting an exhaust pouring principle to backfill concrete into a backfill bin, so as to solve the problem of concrete pouring in a closed space; the high-flow-state self-leveling self-compacting concrete is adopted, so that the problem that the construction of backfilling concrete in a closed space cannot carry out bin surface vibration operation is solved; and the high-pressure water jacking contact grouting is performed by using the rock surface contact grouting principle, so that leakage water is blocked, and backfilled concrete is closely contacted with the rock. The invention is used for reconstruction, expansion and repair of hydraulic underground buildings.

Description

Concrete backfilling method for sealed space leakage vertical shaft under high external water pressure

Technical Field

The invention relates to the field of water conservancy and hydropower engineering, in particular to a method for backfilling concrete in a vertical shaft with high external water pressure, high ground water level and severe leakage water burst and in a closed space.

Background

The reconstruction, extension, reinforcement maintenance or disease treatment of hydraulic buildings usually meet the conditions of narrow space, high external water pressure, high groundwater level, severe leakage water burst and even underwater operation, and the construction difficulty is extremely high.

The doro hydropower station is affected by earthquake, and a shaft concrete structure of a shaft type gate chamber of a reservoir original emptying hole arranged in a mountain body on the right bank of a dam is subjected to shearing damage, so that a shaft of a gate shaft is cracked and misplaced, water leakage of the gate chamber and deformation of a gate rail are caused, and a gate cannot be normally opened and closed. Repeated demonstration proves that the reconstruction of the vent hole is determined. The arrangement scheme of the reconstructed vent hole is as follows: the vent hole inlet is arranged at the lower part of the flood discharge hole inlet at the position close to the dam of the right bank storage area, and the reconstructed vent hole axis is obliquely crossed with the original vent hole axis and is combined with the original vent hole through a vertical shaft; the rebuilding emptying hole comprises a pressure inlet, a pressure hole section, a hydraulic gate chamber (namely an underground gate chamber), a non-pressure hole section and an outlet section, wherein the non-pressure hole section behind the gate chamber utilizes the original emptying hole. The pressure hole section sequentially comprises an upper flat section, an upper bent section, a lower bent section and a lower flat section along the flow direction, the sections are in smooth transition, and the construction branch hole is connected to the upper flat section.

And the construction of reconstructing the cavity is carried out in two stages according to the time node requirements of reservoir emptying and secondary gate discharging and water storage. The first stage is to empty the reservoir through the original hollow, and complete the construction of digging and supporting the supporting hole, the construction of the water inlet tower, the digging and supporting of the upper flat section and the upper bending section, the lining construction before the upper flat Duan Mou pile number, the lining construction of the upper bending section, the digging and supporting of the sluice chamber traffic hole and the upper portion of the sluice chamber. And a rock plug is reserved at the lower part of the vertical well, and excavation is not carried out temporarily, so that the water in the original emptying hole is conveniently discharged.

And in the second stage, the original vent hole is plugged, the underground bent section of the vent hole is reconstructed, the underground bent section is excavated and supported, the lower bent section, the lower flat section steel lining is installed, backfilled concrete is poured, the lower flat section tunnel is lapped, curtain grouting is carried out, and lining concrete at the upper part of the sluice chamber is poured and concreted and grouted. After the construction is completed, the original reinforced concrete of the top arch of the gate chamber is broken and detached, then the side wall of the lower part of the gate chamber is excavated and supported from top to bottom, the foundation of the gate chamber is excavated, then the concrete casting of the lower part of the gate chamber, the installation of the gate and the opening and closing equipment thereof are carried out, and meanwhile, the joint installation of the upper flat section, the concrete backfilling and the construction supporting hole plugging are carried out.

In the second stage construction, when the construction of the original emptying hole plugging section is completed, after the reserved rock plug section at the lower part of the vertical well is excavated and penetrated, the external water pressure water head of the excavated and formed vertical shaft is as high as 87-100 m. Because the single thin ridge rock mass crack on the right bank of the dam where the vertical shaft is positioned develops and has stronger water permeability, and the vertical shaft is positioned on the upstream side of the impermeable curtain of the dam abutment on the right bank of the dam, the seepage and water burst along the rock mass crack surface of the peripheral ring of the vertical shaft are serious under the action of high external water pressure of the reservoir water, and the vertical shaft is in jet flow type water burst. When the steel lining of the lower bent section of the vertical shaft is installed and welded and the concrete is filled in the subsequent backfilling, the conditions that the construction operation surface is narrow, the welding cannot be performed under the influence of the driven water and the concrete backfilling construction cannot be performed are faced.

Because of the special construction environment and construction procedure, the problem of 'carrying out the backfill concrete construction of the vertical shaft in the closed space under the conditions of high external water pressure and severe leakage water gushing' is formed. For this problem, the construction can be performed according to the following two conventional methods. Scheme one: and (3) carrying out steel lining installation and backfill concrete construction on the shaft which is excavated in the first construction stage, and carrying out shaft steel lining installation and backfill concrete construction from bottom to top after the reserved rock plug section at the lower part of the shaft in the second construction stage is excavated and penetrated, wherein the steel lining installation and the backfill concrete construction are alternately carried out. Scheme II: after the whole vertical shaft is excavated and penetrated, the whole vertical shaft section is sequentially segmented from top to bottom to carry out water leakage blocking treatment, and after the water leakage is blocked, the first scheme is adopted for construction.

The scheme I is suitable for the condition that no or little underground water seepage exists in the vertical shaft. In this engineering, after the reservoir impounds again, because the effect of high external water pressure, the shaft wall crack that is located in the bank mountain body will appear a large amount of strand form seepage gushes water, leads to producing a large amount of flowing water in the shaft, adopts the scheme one to carry out follow-up steel lining installation and backfill concrete placement construction under the water state of moving, will not normally operate. In addition, the construction period of this scheme is longer, and the shaft of earlier excavation is because can not obtain in time lining, and exposure time extension, the country rock produces relaxation deformation easily under the infiltration effect, and is unfavorable to shaft country rock stability.

The scheme II is suitable for a vertical shaft with small leakage water inflow, and water seepage is easy to control and block. However, in the engineering, due to the full supply of the reservoir and the action of high external water pressure, a great amount of continuous leakage water burst exists in the vertical shaft, the construction operation space of the vertical shaft is limited due to the fact that the section of the vertical shaft is relatively smaller, the plugging and grouting operation under the condition of no cover weight in the vertical shaft is carried out under the influence of moving water, the plugging construction difficulty is high, and the plugging effect and the construction period for plugging are not guaranteed and mastered. In addition, the grouting slurry is seriously lost due to the influence of high-water-pressure dynamic water, so that the grouting slurry has certain pollution to water and environment, and the grouting slurry is particularly suitable for chemical grouting.

Under the conditions of high external water pressure and leakage water burst, if concrete pouring is performed without water shutoff and drainage measures on the surface of the concrete warehouse due to the influence of the action of water movement, a large amount of mortar is lost due to the influence of the leakage water burst, the quality of concrete cannot be ensured, and concrete pouring under the conditions is not allowed in the current hydraulic concrete construction Specification in China. In addition, after the installation of the steel lining of the lower bent section of the vertical shaft is completed, backfill concrete must be poured layer by layer from bottom to top, so that after the backfill concrete pouring of the original emptying hole part at the lower part is completed, the vertical shaft section forms a closed annular cavity with a certain height. The backfill concrete pouring is carried out in the narrow and airtight space, and on the premise that the steel pipe is not allowed to be perforated and the worker cannot enter the bin to carry out flat bin vibration on the in-bin concrete, the problem that needs to be solved is how to ensure that the backfill concrete can be poured compactly.

Disclosure of Invention

The invention provides a concrete backfilling method for a sealed space seepage vertical shaft under high external water pressure, which solves the adverse effect of a large amount of seepage water in the vertical shaft on steel lining installation and backfilling concrete pouring.

The technical scheme adopted by the invention is as follows: the method for backfilling the concrete in the airtight space leakage vertical shaft under high external water pressure comprises the following steps S1-S5, wherein the front section of the vertical shaft is a steel pipe lining after construction is completed, the rear section of the vertical shaft is communicated with an original emptying hole.

S1, embedding a water-blocking drainage facility.

S1.1, installing a top drainage exhaust pipeline: the bottom surface and the rock wall of the steel pipe lining of hugging closely the shaft anterior segment, fixed mounting top annular drainage exhaust festoon pipe, top annular drainage exhaust festoon pipe downside trompil and fixed connection vertical drainage blast pipe, top annular drainage exhaust festoon pipe and vertical drainage blast pipe intercommunication, vertical drainage blast pipe is arranged downwards and is laid outside plug template mounted position, and vertical drainage blast pipe's end sets up high-pressure stop valve.

S1.2, installing a vertical drainage flower pipe: vertical drainage flower pipes are arranged at intervals along the rock wall surface of the vertical shaft, the upper ends of the vertical drainage flower pipes are fixedly connected and communicated with the top annular drainage and exhaust flower pipes, and the vertical drainage flower pipes are fixedly arranged on the rock wall surface.

S1.3, installing a water stop plate: and the water-stop plate is laid on the rock wall surface in a comprehensive manner and fixedly arranged on the rock wall surface. For example, the water-stop plate is a wavy color steel tile, and the color steel tiles are mutually overlapped up and down and left and right.

S1.4, installing a water collecting tank and a water discharging pipe: the water collecting tank is fixedly installed along the outlet of the lower end of the vertical shaft, the lower end of the water baffle is inserted into the water collecting tank, at least one drain hole is formed in the bottom of the water collecting tank, the bottom of the drain hole is connected with a drain pipe, the drain pipe is led out of an original emptying hole outside the installation position of the plug template to drain water, and a high-pressure stop valve is further arranged at the outlet end of the drain pipe.

S2, installing a steel liner at the rear section of the vertical shaft.

Specific: step S2 includes the following steps S2.1 and S2.2.

S2.1, placing a winch in a steel pipe lined with a steel pipe of which the construction is completed at the front section of the vertical shaft, and reserving a construction passage; and erecting a supporting system at the outlet of the lower end of the vertical shaft in the original cavity, and erecting a sliding rail for transporting the steel lining on the supporting system.

S2.2, the steel bushing to be installed consists of at least two pipe sections, the pipe sections are dragged to the installation position one by one through a winch and a sliding rail for positioning and welding, and all the pipe sections are installed sequentially from top to bottom.

Further is: in the step S2.2, after the pipe joint to be installed is lifted to an installation station through a winch, the pipe joint to be installed is fixed and positioned through three positioning guide chains uniformly distributed along the inner wall of the vertical shaft; after positioning, the pipe joint to be installed is initially connected with the steel pipe lined after construction or the pipe joint after installation, a pipe joint supporting system and a welding operation platform are built, connection between the pipe joint to be installed and a winch is released, and welding operation of the pipe joint to be installed is performed.

Specific: the steel lining comprises three pipe joints, namely a reducer pipe connected with the steel pipe lined with the steel pipe which is constructed, a lower bent pipe positioned in the vertical shaft and a lower bent pipe positioned in the original emptying hole.

Specific: the annular welding seams among the pipe joints of the steel lining and between the pipe joints and the steel pipe lined with the steel pipe after construction adopt V-shaped grooves with inward openings, and arc welding is adopted for the annular welding seams.

S3, erecting a plug template between the steel lining and the original emptying hole at the outlet of the steel lining, penetrating and fixing the vertical drainage exhaust pipe and the drain pipe on the plug template, and installing a backfill joint on the plug template, wherein a closed backfill bin is formed by the inner side of the plug template, the hole wall of the original emptying hole, the outer wall of the steel lining and the water stop plate.

Further is: the backfill joints are at least two, each backfill joint is respectively connected with a backfill pipe, and the outlet of each backfill pipe is positioned at different heights of the annular cavity formed by the steel lining and the water stop plate.

Specific: the plug template comprises an upper part and a lower part, the lower part is firstly erected, a construction channel for backfilling concrete is formed between the plug template at the lower part and the hole wall of the original cavity, and the backfilling concrete reaches the height between the highest point and the lowest point of the steel lining outlet; and then setting up the upper part of the plug template, wherein the vertical drainage exhaust pipe, the drainage pipe and the backfill joint are all positioned on the plug template at the upper part.

Further is: and cleaning the backfill bin, roughening the original hole wall in the backfill bin, backfilling the concrete until half of the outlet end of the steel lining is buried in the concrete, and vibrating to be compact.

S4, enabling a high-pressure stop valve at the end of the vertical drainage exhaust pipe to be kept open, or arranging an exhaust pipeline between the highest position of the backfill bin and the plug template, and backfilling concrete into the backfill bin through a backfill joint.

Specific: in step S4, pumping the high-flow-state self-leveling self-compacting concrete to a backfill bin.

S5, after the backfilled concrete reaches a certain age, pure-pressure type top water contact grouting is carried out on the vertical shaft rock face.

Specific: in the step S5, the designed grouting pressure is the sum of the leakage water burst pressure and the initial grouting pressure under the condition of no leakage water burst, the designed grouting pressure is directly adopted as the initial grouting pressure until the grouting is finished, and the concentration classification of the slurry is not carried out.

Further is: in step S5, the slurry discharge concentration and the pipe orifice pressure of the vertical drainage exhaust pipe or the exhaust pipeline are used as the grouting ending basis.

The beneficial effects of the invention are as follows: the invention solves the construction problems of steel lining installation and backfill concrete pouring under the influence of seepage water in the vertical shaft, obtains good technical and economic effects, and ensures the construction quality and construction safety of engineering. The invention can be popularized and applied in the reconstruction/expansion of hydraulic underground buildings, disease repair and other similar underground engineering construction with serious water seepage.

Backfilling concrete into a backfill bin by adopting an exhaust backfill pouring method through a top drainage exhaust pipeline, so that the problem that concrete in a narrow and airtight space which cannot enter a person is difficult to backfill is solved; the backfilled concrete is high-flow self-leveling self-compacting concrete, and the problem that leveling and vibrating can not be performed to ensure compactness during pouring is solved. The construction method breaks through the requirements of hydraulic concrete pouring flat warehouse and vibration in the current hydraulic concrete construction Specification (DL/T5144-2015, SL 677-2014).

The water-stop plate is comprehensively laid on the rock wall surface of the vertical shaft, the water collecting tank and the water drainage pipe are arranged at the outlet of the lower end of the vertical shaft, water seepage is blocked between the water-stop plate and the rock wall surface and is discharged outside through the water drainage pipe, adverse effects of seepage water flow on subsequent steel lining installation and backfill concrete pouring are avoided, basic conditions of high external water pressure, high ground water level and large seepage water inflow vertical shaft steel lining installation and backfill concrete pouring are effectively guaranteed, and steel lining installation and concrete construction can be carried out on a dry land, so that construction quality is guaranteed.

By the construction method of pure pressure type top water contact grouting, the gap between the rock face and the water stop plate and the gap between the joint faces of the new backfill concrete and the old backfill concrete are subjected to contact grouting, so that the close combination between the backfill concrete and the rock face and between the joint faces of the new backfill concrete and the old backfill concrete is achieved, the construction defect is eliminated, and the purpose of blocking water leakage is achieved. The construction method breaks through the application range and the construction technical requirements of the contact grouting in the current technical Specification for cement grouting construction of hydraulic buildings (DL/T5148-2012), and expands and innovates the contact grouting technology.

Aiming at limited construction environment and construction conditions, the steel lining at the rear section of the vertical shaft is installed from top to bottom in sections, and the construction method of backfilling concrete layer by layer from bottom to top after the steel lining is installed is adopted. The construction method breaks through the rule that the steel pipe is installed from bottom to top and is alternately performed with concrete construction in the steel pipe lining clause of the conventional construction Specification of the inclined shaft and the vertical shaft of the hydropower engineering (DL/T5407-2019).

Drawings

Fig. 1 is a schematic view of the pre-buried water blocking drainage facility of the present invention.

Fig. 2 is a cross-sectional view of A-A in fig. 1.

Fig. 3 is a schematic view of fig. 1 at the exit of a steel liner.

Reference numerals: the construction is completed, namely, the steel pipe lining 1, the original cavity 2, the top annular drainage and exhaust pipe 3, the vertical drainage and exhaust pipe 4, the vertical drainage and exhaust pipe 5, the water stop plate 6, the water collecting tank 7, the drain pipe 8, the steel lining 9, the backfill joint 10, the backfill pipe 11 and the system anchor rod 12 are arranged. The unit of elevation notation in fig. 1 is m.

Detailed Description

The invention adopts the measure of combining the blocking and the draining to orderly dredge the leaked water, thereby avoiding the adverse effect of the action of the water on the welding of the steel lining and the backfilling of the concrete. The technical principle of the invention is as follows: firstly, adopting a pre-embedded water-blocking drainage facility, adopting an exhaust pouring principle, and backfilling concrete into a backfill bin through a backfill joint to solve the problem of concrete pouring in a closed space; secondly, high-flow-state self-leveling self-compaction concrete is adopted, so that the problem that the construction of backfilling concrete in a closed space cannot carry out bin surface vibration is solved. Thirdly, the principle of rock surface contact grouting is applied to perform high-pressure top water contact grouting, leakage water burst is blocked, and gaps between the rock surface and the concrete are backfilled, so that the backfilled concrete and the rock can be in close contact.

Aiming at the special conditions that under the condition of high external water pressure, the seepage and water burst of the vertical shaft are serious, and the construction of backfilling concrete in a closed space is carried out, the invention adopts the general technical scheme of combining the pre-embedded water-blocking drainage facility, the layered exhaust backfilling concrete and the high-pressure top water contact grouting, thereby ensuring the construction quality of the backfilling concrete. Firstly, through pre-buried water-blocking drainage facilities, systematic ground waterproof drainage is realized, the problem of seepage and water gushing of the vertical shaft rock wall surface cracks is solved, the influence of the action of water movement on concrete pouring is eliminated, and no ponding and no running water are caused in a concrete backfill bin. Secondly, backfilling concrete from bottom to top by utilizing an exhaust pouring principle; according to the condition of the backfill bin, the concrete can be backfilled layer by layer from bottom to top. Thirdly, in order to solve the problem that personnel cannot enter the warehouse surface to vibrate concrete in the closed space, pumping high-flow-state self-leveling self-compacting concrete is adopted for pouring. Fourthly, the water filling gap between the rock face and the water stop plate and between the new backfill concrete and the old backfill concrete is replaced by slurry and is filled tightly by pure-pressure type top water contact grouting for the rock face of the vertical shaft by utilizing the drain pipe and the vertical drain pipe, so that the dual purposes of plugging water leakage and enabling the backfill concrete to be in close contact with the rock are achieved.

The technical points of the invention can be summarized as follows: firstly, paving a water-stop plate on the rock wall surface of a vertical shaft to isolate seepage water burst of rock mass cracks so as to ensure that the installation of a steel lining and the backfill concrete construction are not affected by water seepage; secondly, arranging a vertical drainage pipe and a top circumferential drainage and exhaust pipe between the water stop plate and the rock face for rock face contact grouting after drainage and backfill concrete in the construction period are finished; thirdly, pumping high-flow-state self-leveling self-compacting concrete, and backfilling the concrete by adopting a method of pumping layer by layer and exhausting pouring layer by layer from bottom to top; and fourthly, after backfilled concrete in the backfill bin reaches a certain age, performing pure-pressure type top water contact grouting by using the buried drain pipe and the vertical drainage exhaust pipe, and filling gaps between the rock wall surface of the vertical shaft and the water stop plate and gaps between the contact surfaces of the poured concrete and the newly poured concrete tightly, thereby playing a role in blocking water leakage.

The DON hydropower station is rebuilt after the earthquake disaster of '8.8' in the nine village ditches, and the invention is further described below by taking the construction of backfilling concrete in a vertical shaft of a rebuilding emptying hole as an example.

The construction of the rear section of the vertical shaft comprises the steps of installing a steel liner 9 at the rear section of the vertical shaft, erecting a plug template at the outlet of the steel liner, forming a backfill bin, backfilling concrete into the backfill bin and grouting the rock surface of the vertical shaft, and particularly comprises the following steps S1-S5.

S1, embedding a water-blocking drainage facility.

The water-blocking drainage facility is finally combined with the backfilled concrete to form a clothing body, so that steel products are adopted. The construction procedure of the embedded water-blocking drainage facility is as follows: installing a top drainage and exhaust pipeline, installing a vertical drainage pipe 5, installing a water stop plate 6, installing a water collecting tank 7 at the bottom end of a vertical shaft and installing a drain pipe 8.

S1.1, installing a top drainage exhaust pipeline.

The top drainage exhaust pipeline comprises a top circumferential drainage exhaust flower pipe 3 and a vertical drainage exhaust pipe 4, wherein the top circumferential drainage exhaust flower pipe 3 is a steel pipe with no through hole on the pipe body, and the vertical drainage exhaust pipe 4 is a steel pipe with no hole on the pipe body. The top annular drainage and exhaust pipe 3 is fixedly arranged on the bottom surface and the rock wall surface of the steel pipe lining close to the front section of the vertical shaft. For example, the top annular drainage and exhaust pipe 3 is fixed by using dowel heads driven into the rock wall, and dowel heads with the diameter of 20mm can be selected. After the top annular drainage and exhaust flower pipe 3 is installed, a hole is formed in the lower side of the top annular drainage and exhaust flower pipe 3 and is fixedly connected with the vertical drainage and exhaust pipe 4, and the top annular drainage and exhaust flower pipe 3 is communicated with the vertical drainage and exhaust pipe 4. For example, holes are formed in the bottom surface of the joint of the two ends of the top circumferential drainage and exhaust pipe 3, and a vertical drainage and exhaust pipe 4 is welded and connected at the holes. The pipe diameters of the top annular drainage and exhaust floral pipe 3 and the vertical drainage and exhaust pipe 4 are determined according to engineering practical conditions, for example, the diameters of the top annular drainage and exhaust floral pipe 3 and the vertical drainage and exhaust pipe 4 are 100mm. The vertical drainage exhaust pipes 4 are downwards arranged and paved outside the installation position of the plug template, and at least one vertical drainage exhaust pipe 4 is arranged, and the installation position is generally one. For example, the vertical drainage and exhaust pipe 4 is arranged close to the surface of the vertical shaft rock wall, the system anchor rods 12 supported by the surrounding rock system are used for fixing, and the dowel bars with the diameter of 20mm can be selected for fixing by adding dowel bars at the place where the system anchor rods 12 cannot be used for fixing according to the firmness degree of reinforcement as required. The end of the vertical drainage exhaust pipe 4 is provided with a high-pressure stop valve, and the high-pressure stop valve is used for removing air and water seepage sealed in a gap when the joint of the rock face contact grouting and the new and old concrete is backfilled and grouted in the later period. The vertical drainage exhaust pipe 4 is paved outside the installation position of the plug template, the concrete position is determined according to the fact that the grouting condition is convenient to observe and the high-pressure stop valve is closed when the rock face is in contact grouting in the later step S5, and meanwhile the installation of the steel lining 9 in the step S2 is required to be free from obstruction.

S1.2, a vertical drain pipe 5 is arranged.

Vertical drainage flower pipes 5 are arranged at intervals along the rock wall surface of the vertical shaft, the upper ends of the vertical drainage flower pipes 5 are fixedly connected and communicated with the top annular drainage and exhaust flower pipes 3, and the vertical drainage flower pipes 5 are fixedly arranged on the rock wall surface.

The vertical drainage pipe 5 is a steel pipe with no through hole on the pipe body, the upper end of the vertical drainage pipe 5 is connected with the top annular drainage exhaust pipe 3 in a welded mode, and the lower end of the vertical drainage pipe is flush with the lower opening of the vertical shaft. The vertical drainage manifold 5 is used for collecting water seepage after the water-stop plate 6 in the early stage and draining the water seepage into the water-collecting tank 7 at the lower port of the vertical shaft, and is used as a slurry inlet channel and a slurry outlet pipeline for the step S5 of the rock surface contact grouting in the later stage. For example, the diameter of the vertical drain pipe 5 is 50mm, and the arrangement pitch of the vertical drain pipe 5 on the shaft rock face is 1m. The vertical drainage pipe 5 is fixed by using a system anchor rod 12 supported by a surrounding rock system, and in places where the system anchor rod 12 cannot be used for fixing, the dowel bar head is properly added for fixing according to the firmness degree of reinforcement, and the dowel bar head with the diameter of 20mm can be selected. In order to ensure the drainage and exhaust effect during the later step S5 rock face contact grouting, the joint of the upper end of the vertical drainage flower pipe 5 and the top annular drainage and exhaust flower pipe 3 is required to be provided with an orifice with the diameter of 45mm on the top annular drainage and exhaust flower pipe 3, then the joint is carried out, and the joint is connected by spot welding.

S1.3, installing a water stop plate 6.

And the water-stop plate 6 is laid on the whole surface of the rock wall, and the water-stop plate 6 is fixedly arranged on the rock wall. The function of the water stop plate 6 is to limit the unordered overflow of the seepage water and guide the collected seepage water and prevent the seepage water from flowing into the construction work surface. For example, the water-stop plate 6 is a wave-shaped color steel tile, and the water-stop plate 6 is mutually overlapped up and down and left and right, so that leakage water is prevented from overflowing from the joint. For example, the water stop plate 6 is a color steel tile, and the model number of the color steel tile is YX20-215-1075.

The water-stop plate 6 is mounted closely to the rock wall surface and is laid along the rock wall surface. In order to ensure the water collecting effect, the lower end of the water-stop plate 6 is required to be flush with the lower opening of the vertical well and can be inserted into the water collecting tank 7 at the bottom end of the vertical well. The fixing of the water stop 6 is carried out by utilizing a system anchor rod 12 supported by a surrounding rock system, and in the place where the system anchor rod 12 cannot be utilized for fixing, the joint bar head is properly added for fixing according to the firmness degree of reinforcement, and the joint bar head with the diameter of 20mm can be selected. In order to ensure that the water-stop plate 6 can be clung to the surface of the rock wall, a circular arc-shaped steel bar sample frame can be respectively arranged at the upper opening and the lower opening of each circle of the water-stop plate 6 to clamp and fix positions, and the steel bar sample frame is fixed by using a system anchor rod 12 supported by a surrounding rock system and a dowel bar head added on the rock wall. In order to ensure the water-blocking effect of the water-blocking plate 6, perforation fixation is not allowed in principle on the water-blocking plate 6, and if the perforation fixation of the water-blocking plate 6 is necessary really because of the reinforcing requirement, after the installation fixation of the water-blocking plate 6 is completed, waterproof sealant is arranged on the perforation circumference to seal the seam.

S1.4, a water collecting tank 7 and a water discharging pipe 8 are arranged.

A circle of water collecting tank 7 is fixedly installed along the outlet of the lower end of the vertical shaft, the lower end of the water baffle 6 is inserted into the water collecting tank 7, at least one drain hole is formed in the bottom of the water collecting tank 7, the bottom of the drain hole is connected with a drain pipe 8, the drain pipe 8 is led out of the original cavity 2 outside the installation position of the plug template for draining, and a high-pressure stop valve is further arranged at the outlet end of the drain pipe 8. The water collecting tank 7 and the water discharging pipe 8 are used for collecting water seepage in the early stage and discharging the water flow to the outside of the backfill bin, and are used as a grouting pipeline for rock surface contact grouting in the later stage.

The water collecting tank 7 is fixed around the intersection line of the vertical shaft and the original emptying hole 2, and the water collecting tank 7 gathers the running water in the vertical drainage pipe 5 and the water seepage flowing down along the rock wall surface of the vertical shaft and the water separation plate 6, and then is discharged outwards through the drain pipe 8. The gap between the water collecting tank 7 and the concrete contact part of the original hollow 2 and the gap between the water collecting tank 7 and the water-proof plate 6 are closed by asphalt waterproof ointment for building, so as to prevent water flow in the water collecting tank 7 from leaking. For convenient construction, the water collecting tank 7 is manufactured and molded in sections in a processing workshop outside the hole, and then is transported to the site for fixing, assembling and welding to form an integral construction scheme. The size of the water collection tank 7 is selected according to the water collection amount. For example, the water collecting tank 7 is formed by welding 22a channel steel and a steel plate with the thickness of 5mm, is in an L-shaped shape, the actual shape of a shaft outlet is measured on site before the water collecting tank 7 is welded, and the manufacturing section is determined according to the measured result and the maximum single piece weight required by installation. At least one drain hole is arranged at the bottom of the water collecting tank 7, and the drain hole is connected with a drain pipe 8. For example, drain holes having a diameter of 140mm are opened at the bottoms of both sides of the water collecting tank 7, and then drain pipes 8 having a diameter of 150mm are butted with the drain holes and welded. When there are a plurality of drain pipes 8, each drain pipe 8 preferably merges into one drain port, and then the water flow is discharged to the outside of the backfill bin in the original cavity. For example, drain holes are respectively arranged at the lowest positions of the water collecting tank 7 intersecting with the side walls at the two sides of the original emptying hole wall and are connected with drain pipes 8, and the drain pipes 8 are led to the height of 2266.0m along the side walls at the two sides of the original emptying hole 2, then are combined together and are led out of the backfill bin. The outlet end of the drain pipe 8 is also provided with a high-pressure stop valve for controlling water flow when contact grouting and water seepage plugging are carried out after the concrete backfilling is completed. For example, the outlet end of the drain pipe 8 is welded with a flange, and a high-pressure shut-off valve is again installed.

S2, installing a steel liner 9 at the rear section of the vertical shaft.

The steel lining 9 enters the vertical shaft through the original emptying hole 2 for installation and is welded with the steel pipe lining 1 of which the front section of the vertical shaft is constructed into a whole.

A specific arrangement of the steel lining 9 is provided below, step S2 comprising the following steps S2.1 and S2.2.

S2.1, placing a winch in a steel pipe of the steel pipe lining 1 of which the construction is completed at the front section of the vertical shaft, and reserving a construction passage; and a supporting system is erected at the outlet of the lower end of the vertical shaft in the original emptying hole 2, and a sliding rail for transporting the steel liner 9 is erected on the supporting system.

The hoist is used for hauling the pipe sections constituting the steel lining 9. The joint of the upper flat section of the front section of the vertical shaft is not installed temporarily, and the space reserved by the construction branch hole of the upper flat hole and the joint is used as an upper entrance and construction channel; and a construction crawling ladder is arranged in the upper bent pipe installed at the front section of the vertical shaft for construction operators to pass through. And a supporting system is erected at the outlet of the lower end of the vertical shaft in the original emptying hole 2, and a sliding rail for transporting the steel liner 9 is erected on the supporting system. The support system is a welded steel support and is used for erecting a sliding rail and also used for the foundation of a temporary supporting structure for steel lining installation.

S2.2, the steel bushing 9 to be installed consists of at least two sections of pipe joints, the pipe joints are dragged to the installation position one by one through a winch and a sliding rail for positioning and welding, and all the pipe joints are installed sequentially from top to bottom.

Because the steel lining 9 has large mass, the steel lining 9 is composed of at least two pipe sections, the pipe sections are dragged to the installation position one by one for positioning and welding, and all the pipe sections are installed in sequence from top to bottom. The material, thickness, number of pipe sections and single-section length of the steel liner 9 are determined according to engineering conditions and construction conditions. For example, the steel lining 9 is rolled by a steel plate with Q345R and 16mm thickness, the steel lining 9 comprises three pipe joints, namely a reducer pipe connected with a steel pipe of the steel pipe lining 1 which is constructed, a lower bent pipe positioned in a vertical shaft and a lower bent pipe positioned in the original vent hole 2, and the construction procedure of the steel lining 9 is as follows: reducing pipe installation, shaft inner lower elbow installation and original hollow inner lower elbow installation. When the steel lining 9 is installed, the pipe joint is transported into the hole from a stacking yard outside the original hollow hole 2 by using a flat trailer and unloaded on the slide rail according to the joint condition of the pipe joint, and then the pipe joint is dragged to an installation position through the slide rail and a winch for positioning and welding. In order to facilitate pipe joint unloading and positioning, the flat trailer adopts a reversing mode to enter the hole. After the construction of the rear section of the vertical shaft is completed, namely the thickness of the step S5 of the invention, the reserved joint of the flat section is installed, the ladder stand in the front section of the vertical shaft is removed, then the concrete of the joint part is backfilled, and finally the blocking and lining of the construction support hole are carried out.

After the pipe joint is placed on the sliding rail, the pipe joint is jointly conveyed to the lower portion of the shaft outlet through the guide chain and the jack, the pipe joint is inverted and turned through the winch, the pipe orifice is upward, and then the winch vertically lifts the pipe joint to the installation station. After the pipe joint to be installed is lifted to the installation station through the winch, the pipe joint to be installed is fixed and the installation position is adjusted through three positioning guide chains uniformly distributed along the inner wall of the vertical shaft. The hooks of the positioning guide chains are hung on anchor rings anchored in original backfill concrete or anchor frames anchored in rock mass of the tunnel wall, and the lifting hooks are hung on lifting lugs welded on the outer sides of the pipe joints. After the pipe joint positioning work is finished, spot welding connection is performed on the installed steel pipe and the pipe joint to be fixed in time, so that preliminary fixing of the installed steel pipe and the pipe joint to be fixed is realized; and then constructing or installing a pipe joint supporting structure to form a pipe joint supporting system and a welding operation platform. After the pipe joint supporting structure is completed, the connection between the pipe joint to be installed and the winch is released, the lifting force of the winch on the pipe joint disappears, and then welding operation is carried out. After the pipe joint connection girth is welded and qualified through ultrasonic flaw detection, the connection between the positioning guide chain and the installed pipe joint is released, and then the next pipe joint is hoisted.

The annular welding seam between the pipe joint and the steel pipe lined by the steel pipe after construction and between the pipe joints adopts a V-shaped groove with an inward opening, the annular welding seam adopts manual arc welding, and the welding seam is subjected to nondestructive detection in an ultrasonic flaw detection mode, so that 100% flaw detection is required to be carried out on each annular seam.

S3, erecting a plug template and forming a backfill bin.

And a plug template is erected between the steel lining 9 and the original vent hole 2 at the outlet of the steel lining 9, and the outlet of the steel lining 9 penetrates out from the middle part of the plug template. The vertical drainage exhaust pipe 4 and the drain pipe 8 are all penetrated and fixed on the plug template, and the inner side of the plug template, the hole wall of the original cavity 2, the outer wall of the steel liner 9 and the water stop 6 enclose a closed backfill bin.

The plug template is also provided with a backfill joint 10, and the backfill joint 10 is used for backfilling concrete into the backfill bin. The backfill joint 10 can be one or two or more, the backfill joints 10 are respectively connected with the backfill pipes 11, and the backfill pipes 11 are positioned in the backfill bin. When the number of the backfill joint 10 and the backfill pipes 11 is two or more, the outlet of each backfill pipe 11 is positioned at different heights of the annular cavity formed by the steel liner 9 and the water stop 6 so as to facilitate layered backfill.

When the backfill pipes 11 are two or more, one end of one backfill pipe 11 which is not connected with the backfill joint 10, that is, the end with higher position can be fixed on the bottom surface of the steel pipe lining of the front section of the vertical shaft, the backfill pipe 11 is used as an exhaust pipeline, is not used for backfilling concrete, is used for balancing the air pressure of the backfill concrete, is also used for judging whether the backfill concrete is finished or not, and is also used for carrying out pure pressure type top water contact grouting on the rock surface of the vertical shaft.

The whole backfill bin can be directly backfilled by filling concrete through the backfill joint 10, but as the lower part of the backfill bin, namely the part positioned in the original emptying hole 2, has the condition of conventional backfill construction, a part of plug templates can be firstly erected, the lower part of the backfill bin is backfilled with concrete, then the rest plug templates are erected, and then the backfill is performed by filling concrete through the backfill joint 10. Specifically, the plug template comprises an upper part and a lower part, the lower part is firstly erected, a construction channel for backfilling concrete is formed between the plug template at the lower part and the hole wall of the original emptying hole 2, the height between the highest point and the lowest point of the backfilling concrete to the outlet of the steel lining 9 is increased, the backfilling concrete has a stabilizing effect on the outlet end of the steel lining 9, and meanwhile, the backfilling pipe 11 is convenient to install. For example, the concrete is backfilled until half of the outlet end of the steel liner 9 is buried in the concrete and compacted by vibration. After the concrete backfilling of the lower part of the plug template is completed, the upper part of the plug template is erected, and the vertical drainage exhaust pipe 4, the drainage pipe 8 and the backfilling joint 10 are all positioned on the plug template on the upper part. In order to ensure that the backfill concrete and the lining concrete of the original cavity 2 can be well combined, the surface of the cavity wall of the original cavity 2 in the backfill cabin is subjected to roughening treatment before backfilling the concrete. And before backfilling the concrete, cleaning the bottom of the backfill bin.

For the engineering example corresponding to the invention, the backfill bin is not large, meanwhile, the construction convenience of the pre-buried facilities used for vertical shaft backfill concrete pouring is considered, and in order to reduce the pipe blocking probability when the vertical shaft section pumps concrete, a scheme of balanced ascending and layered pouring of the full section from bottom to top is adopted. The backfill concrete of the original cavity 2 at the lower part is poured in two layers, and the thickness of each layer is about 4 m. The first layer is poured from the bottom building base surface to the elevation 2266.00m, and half of the outlet end of the steel lining 9 is buried into the concrete by the first layer of concrete, so that the purposes of fixing the lower end of the steel lining 9 and stabilizing locking feet are achieved, and meanwhile the backfill pipe 11 is convenient to install. The second layer of backfill concrete from the elevation 2266.00m to the lower end outlet of the vertical shaft, namely backfill concrete to the top of the original caving hole 2, and the second layer of concrete fills the original caving hole completely, so that a closed annular cavity is formed in the vertical shaft section. And the backfill concrete of the shaft section is poured in three layers, and the pouring thickness is layered according to about 3 m. Layering of the backfill concrete of the backfill warehouse located in the vertical shaft is shown in fig. 1, the backfill concrete is put into the warehouse in a pumping mode, and relevant technical parameters of each pouring warehouse surface are shown in the following table.

Table 1 backfill bin backfill concrete parameters table.

Layering	Engineering part	Area of bin surface/m 2	Casting elevation/m	Concrete strength	Engineering quantity/m 3
						First layer	The lower part of the original emptying hole	24 (rectangle)	2262.000～2266.000	C20	91.0
Second layer	The upper part of the original cavity	24 (rectangle)	2266.000～2270.242	C20	69.0
						Third layer	Vertical shaft	6.43 (Ring shape)	2270.000～2273.000	C20	21.0
Fourth layer	Vertical shaft	6.43 (Ring shape)	2273.000～2276.000	C20	19.5
						Fifth layer	Vertical shaft	6.43 (Ring shape)	2276.000～2278.585	C20	15.6

Before the first layer of concrete is constructed, a building base surface is cleaned. Because the foundation surface with the elevation of 2262.00m is a newly excavated foundation surface, loose block stones are required to be cleaned on the foundation surface before concrete pouring, the foundation surface is cleaned by high-pressure water, and a plug template is installed after foundation acceptance. And draining accumulated water on the building base surface before concrete pouring. The steel lining 9 is arranged at the installation position of the plug template, so that the plug template belongs to a special-shaped plane, and is formed by mixing and splicing a wood template and a bamboo plywood for the convenience of supporting and forming. The first layer of concrete adopts common pumping secondary concrete, after being stirred at a concrete mixing station outside a hole, the first layer of concrete is transported into the hole from a flat hole below an emptying hole by a concrete stirring transport vehicle, and then is pumped into a bin through a pumping pipeline by a concrete conveying pump, and a vibrator flat bin is adopted during pouring, for example, an electric flexible shaft plug-in vibrator is adopted for vibrating.

S4, backfilling concrete into the backfill bin.

The high-pressure stop valve at the end of the vertical drainage exhaust pipe 4 is kept open, or an exhaust pipeline is arranged between the highest position of the backfill bin and the plug template, so that the air pressure in the backfill bin is balanced, and then the backfill bin is backfilled with concrete through the backfill joint 10. Because the backfill bin is a closed space, and the height of the backfill joint 10 is lower than the height of the top of the backfill bin, operators cannot enter the backfill bin to vibrate during the process of backfilling concrete, and therefore high-flow-state self-leveling self-compacting concrete is pumped into the backfill bin.

Before backfilling the second layer of concrete, roughening treatment is still needed to be carried out on the joint surface of the new and old concrete. To eliminate the defect of the backfill concrete construction of the top arch part of the original hollow 2, the backfill compaction of the top arch part can be ensured, and the concrete is filled in the top arch 120 ⁰ The backfill pipe 11, the vertical drainage exhaust pipe 4 and the drainage pipe 8 are arranged in the range. Since the shaft will form a closed annular cavity after the second layer of concrete is poured, the second layer of concrete needs to be pre-pouredA backfill pipe 11 is installed and the backfill pipe 11, the vertical drain pipe 4 and the drain pipe 8 are inspected. And the second layer adopts pumping first-level high-flow-state self-leveling self-compacting concrete for pouring, constructors do not enter a backfill bin, and pouring construction is completed by means of self-leveling self-compacting performance of the concrete. The mixing, transporting and warehousing modes of the high-flow-state self-leveling self-compacting concrete are the same as those of the first layer.

After the second layer of concrete is backfilled, as the original lining concrete is arranged at the top of the original emptying hole 2, the subsequent backfilling construction is not influenced by seepage water, and the backfilling grouting construction of the annular cavity formed by the steel lining 9 at the upper part of the backfilling bin does not need to take special technical measures, and can be performed according to the conventional backfilling grouting process. And the backfilling of the annular cavity at the upper part of the backfilling bin and the backfilling construction of the second layer of concrete are synchronously carried out.

For the engineering example corresponding to the invention, the elevation of the annular cavity at the upper part of the backfill bin is 2270.000-2278.585 m, and the backfill concrete engineering amount is about 56.1m ³ . The annular cavity is divided into a third layer to a fifth layer in the front, namely, the annular cavity is divided into three bins, and because the backfill concrete amount of each pouring layer is relatively small, if layered pouring is adopted, after pouring is intermittent, the joint surfaces of new and old concrete cannot be treated, and meanwhile, leakage water can be possibly formed in the bins in the intermittent period. In order not to influence the concrete pouring quality, the backfilling concrete pouring of the annular cavity is completed by adopting a continuous pumping mode without stopping. In order to avoid pumping blocking in the pouring process, the backfill pipe 11 is pre-buried according to three layers, the height of the outlet of the backfill pipe 11 of the first layer from bottom to top is 2273.000m, the height of the outlet of the backfill pipe 11 of the second layer is 2276.000m, and the height of the outlet of the backfill pipe 11 of the third layer is 2278.500m. When the lower backfill pipe 11 is used for conveying concrete to a warehouse, the upper backfill pipe 11 is used as an exhaust pipe, and the top annular drainage exhaust flower pipe 3 and the vertical drainage exhaust pipe 4 also have the exhaust function. The bottom surface 2278.585m of the steel pipe lining close to the front section of the vertical shaft is provided with a backfill pipe 11 which is used as a drainage and exhaust pipe and is used for sealing the cabin for exhausting air and draining water seeping from the cabin surface and seeping and accumulated water in the cabin during the pouring of the third layer of concrete.

The annular cavity at the upper part of the backfill bin is poured by adopting a first-stage high-flow-state self-leveling self-compacting concrete, the concrete is stirred by a concrete mixing station arranged outside the hole, a concrete mixing transport vehicle is used for transporting the concrete into the hole from the lower flat hole of the emptying hole, and then the concrete is pumped into the bin through a pumping pipeline by a concrete conveying pump. In the concrete backfilling process, a temporary crawling ladder arranged in the steel lining 9 during installation is utilized, and the rising height of concrete in the backfilling bin is judged by a method of knocking the inner wall of the steel lining 9 manually through a small hammer. When the third layer of concrete is poured, thick cement paste or concrete flows out of the backfill joint 10 corresponding to the backfill pipe 11 serving as the drainage and exhaust pipe, or the concrete is not fed in the pumping process (except for the condition of pipe blockage of the pump pipe), the concrete in the annular cavity is proved to be filled back, and the bin can be collected.

S5, performing pure-pressure type top water contact grouting on the vertical shaft rock surface.

And after the backfilled concrete in the backfill bin reaches a certain age, pure-pressure type top water contact grouting is performed on the vertical shaft rock surface by utilizing the drain pipe 8 and the vertical drain exhaust pipe 4, or pure-pressure type top water contact grouting is performed on the vertical shaft rock surface by utilizing the drain pipe 8 and the exhaust pipeline, or pure-pressure type top water contact grouting is performed on the vertical shaft rock surface by utilizing the drain pipe 8, the vertical drain exhaust pipe 4 and the exhaust pipeline.

For grouting pressure, as the pressure water burst exists in the rock wall surface cracks, and the gap between the vertical shaft rock surface and the water stop plate is in a water filling state, the contact grouting pressure under the normal condition according to the current technical Specification for cement grouting construction of hydraulic buildings (DL/T5148-2012) cannot be applied. Therefore, the grouting pressure is designed to be the sum of the leakage water burst pressure and the initial grouting pressure in the case of no leakage water burst. The designed grouting pressure is the actual grouting pressure, and the numerical value of the seepage water surge pressure of the rock wall surface is obtained through the water blocking and draining facility by performing a field water blocking test.

For example, according to the actual measurement result of the water closing test, the leakage water burst pressure is 1MPa at the maximum. The initial grouting pressure is determined to be 0.5MPa according to the specification of the current hydraulic building grouting construction technical Specification (DL/T5148-2012) on the contact grouting pressure, namely according to the specification that the pressure of a contact grouting slurry inlet pipe is not more than 0.5MPa or 0.6MPa, and the control pressure of an exhaust pipe is not more than 0.2MPa or 0.3 MPa. Through calculation, the designed grouting pressure of the engineering takes 1.5MPa.

The pure pressure type top water contact grouting is constructed by adopting a pure pressure type single thick slurry one-time grouting process. The grouting pressure does not adopt a step-by-step boosting mode, and the initial grouting pressure directly adopts the designed grouting pressure of 1.5MPa for grouting. And in the grouting process, the grouting pressure is measured and adjusted by reading the pressure gauge at the grouting orifice in time, and grouting pressure control is performed until grouting is completed according to the ending standard.

The slurry used for pure pressure type top water contact grouting is prepared intensively by a pulping station arranged outside the hole, and is conveyed to the in-hole grouting station by an SNS130/20 grouting pump through a high-pressure rubber pipe with the diameter of 32 mm. The grouting equipment uses a JK-800 high-pressure grouting machine, and an automatic grouting recorder is adopted for grouting record. Grouting is performed with a pure cement slurry, for example with a strength grade of 42.5 using cement. Since the leakage water is present in the gaps, the slurry is not classified, and is directly poured by thick slurry, and a single-mixing-ratio slurry with a water-cement ratio of 1:1 is adopted. In order to prevent the waste slurry from polluting the environment, the waste slurry discharged by the vertical drainage exhaust pipe 4 and the exhaust pipeline is led into a waste slurry pool for centralized collection and recovery. The waste slurry tank can be welded by steel plates so as to be convenient to move and carry.

The end standard of the pure pressure type top water contact grouting is the slurry discharging concentration and the pipe orifice pressure of the vertical water discharging exhaust pipe 4 and the exhaust pipe. For example, when the pulp discharge concentration reaches or approaches the pulp inlet concentration, and the nozzle pressure reaches or approaches 0.3MPa, the grouting is continued for 20min, and the pulp is shielded for 10min, so that the grouting can be finished.

Claims (10)

1. The concrete backfilling method for the leakage shaft of the closed space under high external water pressure is characterized by comprising the following steps: the front section of the vertical shaft is a steel pipe lining (1) which is constructed, the rear section of the vertical shaft is communicated with an original emptying hole (2), and the construction of the rear section of the vertical shaft comprises the following steps:

S1, embedding a water-blocking drainage facility;

s1.1, installing a top drainage exhaust pipeline: the bottom surface and the rock wall surface of the steel pipe lining close to the front section of the vertical shaft are fixedly provided with top annular drainage and exhaust flower pipes (3), the lower side of each top annular drainage and exhaust flower pipe (3) is provided with a hole and is fixedly connected with a vertical drainage and exhaust pipe (4), each top annular drainage and exhaust flower pipe (3) is communicated with each vertical drainage and exhaust pipe (4), each vertical drainage and exhaust pipe (4) is downwards arranged and paved outside the installation position of the corresponding plug template, and the end head of each vertical drainage and exhaust pipe (4) is provided with a high-pressure stop valve;

s1.2, installing a vertical drainage flower pipe (5): vertical drainage flower pipes (5) are arranged at intervals along the rock wall surface of the vertical shaft, the upper ends of the vertical drainage flower pipes (5) are fixedly connected and communicated with the top annular drainage and exhaust flower pipes (3), and the vertical drainage flower pipes (5) are fixedly arranged on the rock wall surface;

s1.3, installing a water-stop plate (6): a water-stop plate (6) is fully laid against the rock wall surface, and the water-stop plate (6) is fixedly arranged on the rock wall surface;

s1.4, a water collecting tank (7) and a water discharging pipe (8) are arranged: a circle of water collecting tank (7) is fixedly arranged along an outlet at the lower end of the vertical shaft, the lower end of the water collecting plate (6) is inserted into the water collecting tank (7), at least one drain hole is formed in the bottom of the water collecting tank (7), the bottom of the drain hole is connected with a drain pipe (8), the drain pipe (8) is led out of the original cavity (2) outside the installation position of the plug template for draining, and a high-pressure stop valve is further arranged at the outlet end of the drain pipe (8);

S2, installing a steel liner (9) at the rear section of the vertical shaft;

s3, erecting a plug template between the steel lining (9) and the original emptying hole (2) at the outlet of the steel lining (9), penetrating and fixing the vertical drainage exhaust pipe (4) and the drainage pipe (8) on the plug template, and installing a backfill joint (10) on the plug template, wherein a closed backfill bin is formed by enclosing the inner side of the plug template, the hole wall of the original emptying hole (2), the outer wall of the steel lining (9) and the water-stop plate (6);

s4, enabling a high-pressure stop valve at the end of the vertical drainage exhaust pipe (4) to be kept open, or arranging an exhaust pipeline between the highest position of the backfill bin and the plug template, and backfilling concrete into the backfill bin through a backfill joint (10);

s5, after the backfilled concrete reaches a certain age, pure-pressure type top water contact grouting is carried out on the vertical shaft rock face.

2. The method for backfilling concrete in a closed space leakage shaft under high external water pressure according to claim 1, wherein: step S2 includes the following steps S2.1 and S2.2:

s2.1, placing a winch in a steel pipe of the steel pipe lining (1) of which the construction is completed at the front section of the vertical shaft, and reserving a construction passage; a supporting system is erected at the outlet of the lower end of a vertical shaft in the original emptying hole (2), and a sliding rail for transporting a steel liner (9) is erected on the supporting system;

S2.2, the steel bushing (9) to be installed consists of at least two pipe sections, the pipe sections are dragged to the installation position one by one through a winch and a sliding rail for positioning and welding, and all the pipe sections are installed sequentially from top to bottom.

3. The method for backfilling the concrete in the airtight space leakage vertical shaft under the high external water pressure as claimed in claim 2, wherein the method comprises the following steps: in the step S2.2, after the pipe joint to be installed is lifted to an installation station through a winch, the pipe joint to be installed is fixed and positioned through three positioning guide chains uniformly distributed along the inner wall of the vertical shaft; after positioning, the pipe joint to be installed is initially connected with the steel pipe of the steel pipe lining (1) which is already constructed or the pipe joint which is already installed, a pipe joint supporting system and a welding operation platform are built, the connection between the pipe joint to be installed and a winch is released, and then the welding operation of the pipe joint to be installed is carried out.

4. The method for backfilling concrete in a closed space leakage shaft under high external water pressure according to claim 1, wherein: in the step S2, the steel lining (9) comprises three pipe joints, namely a reducer pipe connected with the steel pipe of the steel pipe lining (1) which is constructed, a lower bent pipe positioned in the vertical shaft and a lower bent pipe positioned in the original emptying hole (2).

5. The method for backfilling concrete in a closed space leakage shaft under high external water pressure according to claim 1, wherein: in the step S3, at least two backfill joints (10) are arranged, each backfill joint (10) is respectively connected with a backfill pipe (11), and the outlet of each backfill pipe (11) is positioned at different heights of an annular cavity formed by the steel lining (9) and the water stop plate (6).

6. The method for backfilling concrete in a closed space leakage shaft under high external water pressure according to claim 1, wherein: the plug template comprises an upper part and a lower part, the lower part is firstly erected, a construction channel for backfilling concrete is formed between the plug template at the lower part and the wall of the original emptying hole (2), and the backfilling concrete reaches the height between the highest point and the lowest point of the outlet of the steel lining (9); and erecting the upper part of the plug template, wherein the vertical drainage exhaust pipe (4), the drainage pipe (8) and the backfill joint (10) are all positioned on the plug template at the upper part.

7. The method for backfilling the concrete in the airtight space leakage vertical shaft under the high external water pressure according to claim 6, wherein the method comprises the following steps: and cleaning the backfill bin, roughening the wall of the original emptying hole (2) in the backfill bin, backfilling concrete until half of the outlet end of the steel lining (9) is buried in the concrete, and vibrating and compacting.

8. The method for backfilling the concrete in the airtight space leakage vertical shaft under the high external water pressure according to any one of claims 1 to 7, wherein the method comprises the following steps: in step S4, pumping the high-flow-state self-leveling self-compacting concrete to a backfill bin.

9. The method for backfilling the concrete in the airtight space leakage vertical shaft under the high external water pressure according to any one of claims 1 to 7, wherein the method comprises the following steps: in the step S5, the designed grouting pressure is the sum of the leakage water burst pressure and the initial grouting pressure under the condition of no leakage water burst, the designed grouting pressure is directly adopted as the initial grouting pressure until the grouting is finished, and the concentration classification of the slurry is not carried out; and taking the slurry discharge concentration and the pipe orifice pressure of the vertical water discharge exhaust pipe (4) or the exhaust pipeline as the grouting ending basis.

10. The method for backfilling the concrete in the airtight space leakage vertical shaft under the high external water pressure according to any one of claims 1 to 7, wherein the method comprises the following steps: the water-stop plate (6) is a wavy color steel tile, and the color steel tiles are mutually overlapped up and down and left and right; the top drainage exhaust pipeline and the vertical drainage pipe (5) are steel pipes.