阅读说明：本技术 一种适用于硬质地层的水下隧道内垂直顶升实施工法及结构 (Vertical jacking implementation method and structure in underwater tunnel suitable for hard stratum ) 是由 王建仓 李毅 陈娟娟 叶雅图 刘远钗 王秉昌 张俊 刘晗晗 王毅 夏悟民 童军 于 2021-03-23 设计创作，主要内容包括：本发明公开了一种适用于硬质地层的水下隧道内垂直顶升实施工法及结构,实施过程为,首先搭建海上施工平台,在海上平台内打设钢护筒进入硬质稳定地层；然后在护筒保护下钻孔置换立管顶升区的硬质地层；第三步,采用盾构法隧道修建海底主隧洞至顶升区下方；第四步,在主隧洞内通过已经置换的地层逐段垂直顶升立管至海域；第五步,将钢护筒与上部钢结构扩散构筑物连接；第六步,主隧洞充水,打开立管封盖,连接海域与主隧洞实现取/排水功能。本发明能够很好地适用于硬土、岩层等地质条件,其施工方便安全、造价经济、有利于缩短工期、设施稳定性高、工程后期运行更安全可靠。(The invention discloses a vertical jacking implementation method and a vertical jacking implementation structure in an underwater tunnel suitable for a hard stratum, wherein the implementation process comprises the steps of firstly, building an offshore construction platform, and driving a steel casing into the hard stable stratum in the offshore platform; then, drilling under the protection of a pile casing to replace the hard stratum in the jacking area of the riser; thirdly, constructing a main tunnel at the seabed to the lower part of the jacking area by adopting a shield method; fourthly, vertically jacking the stand pipe section by section to the sea area through the displaced stratum in the main tunnel; fifthly, connecting the steel casing with the upper steel structure diffusion structure; and sixthly, filling water into the main tunnel, opening a sealing cover of the vertical pipe, and connecting the sea area with the main tunnel to realize a water taking/discharging function. The invention can be well suitable for geological conditions such as hard soil, rock stratum and the like, has convenient and safe construction, economic manufacturing cost, contribution to shortening the construction period, high facility stability and safer and more reliable operation in the later period of the project.)

1. The utility model provides a perpendicular jacking implementation worker method in tunnel under water suitable for stereoplasm ground which characterized in that: the method comprises the following steps of (1),

firstly, building an offshore construction platform, drilling a pile casing in the construction platform, entering a stable stratum, and exposing the top end of the pile casing above the sea surface;

secondly, drilling under the protection of a pile casing to replace a hard stratum in a riser jacking area;

thirdly, separating the upper section of the pile casing from the lower section of the pile casing to submerge the top end of the lower section of the pile casing below the sea level, and mounting a temporary sealing cover at the top end of the lower section of the pile casing;

fourthly, constructing a main tunnel on the seabed by adopting a shield method tunnel, wherein the main tunnel is communicated to the lower part of the lower section of the casing;

fifthly, vertically jacking the stand pipe section by section to the sea area through the displaced stratum in the main tunnel, and submerging the top end of the stand pipe below the sea surface;

sixthly, connecting the lower section of the pile casing with an upper steel structure diffusion structure, and covering the vertical pipe inside;

and seventhly, filling water into the main tunnel, and opening the jacking sealing cover at the top of the vertical pipe to communicate the main tunnel with the sea area to realize the water taking/draining function.

2. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 1, wherein: the pile casing is made of steel materials and comprises a pile casing upper section and a pile casing lower section which are mutually independent, the pile casing upper section and the pile casing lower section are fixedly connected through a connecting flange, and the connecting flange is positioned 0.8-1.2m above the original mud surface; in the third step, opening the connecting flange underwater, and then hoisting out the upper section of the pile casing; the inner diameter of the protective cylinder is 0.4-0.6m larger than the diameter of the later-stage drilling hole so as to reserve a drilling operation space; the drilling depth of the pile casing is embedded into a stable hard stratum, and the distance from the bottom end of the lower section of the pile casing to the top of the main tunnel is not less than 1 m.

3. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 2, wherein: when the hard stratum is replaced in the second step, the replacement diameter is 0.8-1.2m larger than the outer diameter of the vertical pipe, so that errors in shield main tunnel and jacking construction are reserved; the replacement depth is 0.8-1.2m within the arch crown tunneling range of the main tunnel so as to realize complete occlusion with the main tunnel; and filling non-toxic and harmless materials with the penetration number less than 10 to form a replacement layer during replacement, wherein the replacement materials comprise fine sand and soft soil.

4. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 3, wherein: when the hard stratum is replaced in the second step, a plurality of flushing pipes are embedded in the pile casing at positions close to the inner wall of the lower section of the pile casing, so that flushing resistance reduction is performed when the resistance is too large in the later-stage riser jacking process; the outer wall of the replacement layer is tightly attached to the inner wall of the lower section of the casing, and 6-10 flushing pipes are embedded in the replacement layer at equal intervals along the circumference; the flushing pipe is made of PVC pipe with a diameter of 40-60mm, and plum blossom-shaped flushing holes are arranged at the position of the flushing pipe inserted into the replacement layer along the radial direction at intervals of 0.8-1.2 m.

5. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 1, wherein: the temporary sealing cover is made of a steel structure and is fixedly connected with the lower section of the protective cylinder through a connecting flange, so that the risks of breakdown and pressure relief during the construction of the underwater main tunnel are prevented.

6. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 1, wherein: the upper steel structure diffusion structure is a head sealing cover, the outer diameter of the upper steel structure diffusion structure is 20mm smaller than the inner diameter of the protective cylinder, the upper steel structure diffusion structure is made of a round steel plate and matched with a ribbed plate for sealing, and a water inlet and outlet window is formed in the side surface of the upper steel structure diffusion structure; and performing antiseptic treatment on the head sealing cover according to the service environment and the service life.

7. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 6, wherein: the head sealing cover is preliminarily connected with the lower section of the pile casing through a limiting clamp reserved on the head sealing cover, and then is locked and fixed with the lower section of the pile casing by adopting 12M 30 high-strength bolts.

8. The vertical jacking implementation method suitable for the underwater tunnel in the hard stratum as claimed in claim 1, wherein: after the main tunnel is constructed, steel pipe sheets are arranged at the bottom surface of the main tunnel and the position of the dome, which is aligned with the casing; and a reinforcing supporting part is formed below the steel pipe sheet on the bottom surface of the main tunnel through grouting, and a jacking reaction frame is erected to align to the reinforcing supporting part so as to support the vertical pipe.

9. The utility model provides a structure is implemented in perpendicular jacking in tunnel under water suitable for stereoplasm ground, including main tunnel and riser, its characterized in that: the main tunnel is built in a hard stratum of the seabed, a pile casing is arranged above the main tunnel, the upper end of the pile casing is submerged below the sea surface, and a section of interval is arranged between the lower end of the pile casing and the main tunnel; the inside of the pile casing is filled with a replacement layer formed by nontoxic and harmless materials with the penetration number less than 10 through a drill hole, and the upper end of the vertical pipe penetrates out of the replacement layer and extends into seawater by vertically jacking the vertical pipe upwards from the main tunnel; the upper end of the protective cylinder is fixed with a head sealing cover with a through hole, and the vertical pipe is covered inside the protective cylinder by the head sealing cover.

10. The underwater vertical jacking implementing structure suitable for the hard formation in the tunnel according to claim 9, wherein: the head sealing cover is made of a round steel plate and is sealed by matching with a rib plate, and a through hole is formed in the side surface of the head sealing cover and is used as a water inlet and outlet window; an anti-corrosion structure is arranged on the head sealing cover; the head sealing cover is preliminarily connected with the protective cylinder through a limiting clamp reserved on the head sealing cover, and is locked and fixed with the protective cylinder through a plurality of high-strength bolts.

Technical Field

The invention relates to the technical field of construction of submarine water taking/draining tunnel facilities, in particular to an implementation scheme for vertically jacking an underwater tunnel riser in hard formations such as hard soil, rock and the like.

Background

At present, most domestic and foreign nuclear power stations need to introduce seawater into a condenser for internal circulation and discharge to cool down the nuclear power stations, and in order to reduce the influence on the marine environment, power stations built in recent years mostly adopt a tunnel form to carry out water taking/discharging work, namely, a tunnel is built under a seabed to connect a siphon well of a deep sea and a land area. In consideration of the risk of underwater tunnel construction and the reduction of influence on marine environment, the water taking/discharging tunnel is constructed by adopting a shield construction method in many cases, and after the water taking/discharging tunnel is dug into the deep sea, the water taking/discharging tunnel is connected with the deep sea through a vertical pipe perpendicular to the seabed and the tunnel. At present, the mainstream implementation scheme for connecting the stand pipe in China is that after the construction of the main tunnel is finished, the stand pipe is ejected out of the sea bed surface section by section in the main tunnel in a mode of capping with a cover, finally, a head structure (sealing cover) is covered on the sea bed surface, and after the main tunnel is filled with water, the sealing cover is detached to communicate the main tunnel and the seawater.

Because the method needs to stifle the vertical pipe to the surface of the sea bed in the main tunnel, the stifle needs to overcome the end resistance at the top of the vertical pipe and the side resistance at the side part, and the jacking resistance is larger, the vertical jacking method which is finished in China at present is only suitable for the working condition that the upper part is a soft soil layer (the standard penetration is less than 20 strokes). Meanwhile, in order to facilitate vertical jacking construction, the main tunnel at the position of the vertical pipe needs to be buried as shallowly as possible. Considering the construction safety and the operation safety of the main tunnel at the seabed, the main tunnel should be buried as deep as possible and enter a better stratum. Therefore, for the condition that the penetration number of the standard penetration is large, or the buried depth of the rock stratum and the main tunnel is large, the process of the blind top riser in the tunnel cannot be adopted, and other construction methods such as artificial island excavation and the like which have large influence on the sea area and large investment need to be adopted.

In addition, in order to prevent the pressurized water in the vertical pipe from directly rushing out of the water surface and forming a 'spring hole' to influence the marine environment, a structure needs to be covered on the head of the vertical drainage pipe in engineering practice. In the case of a large ocean current on the seabed, in order to avoid the head structure being washed away by seawater, a large and heavy head structure needs to be made and placed above the vertical pipe. In order to provide a stable foundation for heavy head structures, an overwater dredger needs to be adopted for clearing sludge, throwing and filling broken stones and the like, and therefore not only is more project investment consumed, but also the project period is increased.

Disclosure of Invention

The invention aims to solve the technical problem of the prior art and provides a construction method and a structure for vertically jacking in an underwater tunnel, which are convenient and safe to construct, economical in manufacturing cost, beneficial to shortening the construction period, safer and more reliable in later operation of a project and suitable for a hard stratum.

In order to solve the technical problems, the invention adopts the following technical scheme: the utility model provides a perpendicular jacking implementation worker method in tunnel under water suitable for stereoplasm ground which characterized in that: the method comprises the following steps of (1),

firstly, building an offshore construction platform, drilling a pile casing in the construction platform, entering a stable stratum, and exposing the top end of the pile casing above the sea surface;

secondly, drilling under the protection of a pile casing to replace a hard stratum in a riser jacking area;

thirdly, separating the upper section of the pile casing from the lower section of the pile casing to submerge the top end of the lower section of the pile casing below the sea level, and mounting a temporary sealing cover at the top end of the lower section of the pile casing;

fourthly, constructing a main tunnel on the seabed by adopting a shield method tunnel, wherein the main tunnel is communicated to the lower part of the lower section of the casing;

fifthly, vertically jacking the stand pipe section by section to the sea area through the displaced stratum in the main tunnel, and submerging the top end of the stand pipe below the sea surface; reinforcing the peripheral backfill stratum by injecting cement slurry into the embedded flushing pipe at the periphery of the vertical pipe so as to strengthen and fix the vertical pipe;

sixthly, connecting the lower section of the pile casing with an upper steel structure diffusion structure, and covering the vertical pipe inside;

and seventhly, filling water into the main tunnel, and opening the jacking sealing cover at the top of the vertical pipe to communicate the main tunnel with the sea area to realize the water taking/draining function.

Furthermore, the pile casing is made of steel materials and comprises an upper pile casing section and a lower pile casing section which are mutually independent, the upper pile casing section and the lower pile casing section are fixedly connected through a connecting flange, and the connecting flange is positioned 0.8-1.2m above the original mud surface; in the third step, opening the connecting flange underwater, and then hoisting out the upper section of the pile casing; the inner diameter of the protective cylinder is 0.4-0.6m larger than the diameter of the later-stage drilling hole so as to reserve a drilling operation space; the drilling depth of the pile casing is embedded into a stable hard stratum, and the distance from the bottom end of the lower section of the pile casing to the top of the main tunnel is not less than 1 m.

Furthermore, when the hard stratum is replaced in the second step, the replacement diameter is 0.8-1.2m larger than the outer diameter of the vertical pipe, so that errors in shield main tunnel and jacking construction are reserved; the replacement depth is 0.8-1.2m within the arch crown tunneling range of the main tunnel so as to realize complete occlusion with the main tunnel; and (3) filling non-toxic and harmless materials with the penetration number less than 10 to form a replacement layer during replacement, wherein the replacement materials comprise fine sand, soft soil and the like.

Furthermore, when the hard stratum is replaced in the second step, a plurality of flushing pipes are pre-embedded in the casing at positions close to the inner wall of the lower section of the casing, so that flushing resistance reduction is performed when the resistance is too large in the later-stage riser jacking process; the outer wall of the replacement layer is tightly attached to the inner wall of the lower section of the casing, and 6-10 flushing pipes are embedded in the replacement layer at equal intervals along the circumference; the flushing pipe is made of PVC pipe with a diameter of 40-60mm, and plum blossom-shaped flushing holes are arranged at the position of the flushing pipe inserted into the replacement layer along the radial direction at intervals of 0.8-1.2 m.

Further, interim closing cap adopts the steel construction preparation, and it is connected fixedly through flange and pile section of thick bamboo hypomere to prevent to appear puncturing and pressure release risk during the main tunnel construction under water.

Furthermore, the upper steel structure diffusion structure is a head sealing cover, the outer diameter of the upper steel structure diffusion structure is 20mm smaller than the inner diameter of the protective cylinder, the upper steel structure diffusion structure is made of a round steel plate and matched with a rib plate for sealing, and a water inlet window and a water outlet window are formed in the side surface of the upper steel structure diffusion structure; and performing antiseptic treatment on the head sealing cover according to the service environment and the service life.

Further, the head sealing cover is preliminarily connected with the lower section of the pile casing through a limiting clamp reserved on the head sealing cover, and then is locked and fixed with the lower section of the pile casing by adopting 12M 30 high-strength bolts.

Further, after the main tunnel is built, steel pipe sheets are installed at the bottom surface and the dome of the main tunnel at positions aligned with the casing; and a reinforcing supporting part is formed below the steel pipe sheet on the bottom surface of the main tunnel through grouting, and a jacking reaction frame is erected to align to the reinforcing supporting part so as to support the vertical pipe.

The utility model provides a structure is implemented in perpendicular jacking in tunnel under water suitable for stereoplasm ground, including main tunnel and riser, its characterized in that: the main tunnel is built in a hard stratum of the seabed, a pile casing is arranged above the main tunnel, the upper end of the pile casing is submerged below the sea surface, and a section of interval is arranged between the lower end of the pile casing and the main tunnel; the inside of the pile casing is filled with a replacement layer formed by nontoxic and harmless materials with the penetration number less than 10 through a drill hole, and the upper end of the vertical pipe penetrates out of the replacement layer and extends into seawater by vertically jacking the vertical pipe upwards from the main tunnel; the upper end of the protective cylinder is fixed with a head sealing cover with a through hole, and the vertical pipe is covered inside the protective cylinder by the head sealing cover.

The invention has the following beneficial effects: firstly, the problem that the vertical jacking construction method cannot be applied to the stratum with larger standard penetration number such as hard soil, rock and the like is solved. The vertical jacking construction method has the advantages of low manufacturing cost, good construction safety and high construction efficiency, is a common construction method for solving the problem of connection between the water taking/discharging tunnel and seawater, but the traditional vertical jacking construction method has high requirements on the stratum condition of a jacking position and can only be implemented in a soft soil layer with low penetration number. In recent years, with the large-scale construction development of nuclear power stations at home and abroad, the stratum conditions encountered in the construction process are different, and after the method is adopted, the vertical jacking construction method is not limited by the stratum conditions any more, and particularly, compared with the traditional island-making open cut method, the method can play the roles of reducing the engineering investment, shortening the construction period and reducing the influence of marine environment in hard soil, rock stratum and other places.

And secondly, the novel drainage head steel sealing cover combined with the steel casing can greatly reduce the engineering cost of the drainage head sealing cover, improve the production efficiency and shorten the construction period. In order to avoid the phenomenon that water under pressure of the drainage vertical pipe directly rushes out of the water surface to form a 'spring hole', the top of the drainage vertical pipe needs to be covered with a diffusion sealing cover, the head diffusion sealing cover needs to keep stability under the impact of the water with pressure upwards in the vertical pipe and the impact of horizontal ocean current at the seabed, and the sealing cover is usually designed into a reinforced concrete structure weighing hundreds of tons in the traditional method. In order to place a head structure weighing hundreds of tons, a soft sludge layer on the upper part is removed by dredging at the seabed of the marine dredger, and then a cushion layer such as broken stones is filled and filled as a foundation. The invention can change the head diffusion sealing cover into light steel structure, and at the same time, the invention connects the light steel structure sealing cover with the steel pile casing used in stratum replacement to form a pile-cap structure with the pile casing as the 'pile' and the head steel sealing cover as the cap, which has enough stability in use, not only can prevent the high pressure water in the vertical pipe from directly flushing the sea surface, but also can form omnibearing permanent protection for the vertical pipe.

And thirdly, the buried depth of the underwater main tunnel can be increased, and the safety of construction and operation of the main tunnel is improved. When the tradition was got/drainage tunnel design, in order to make the later stage riser can follow the construction of jacking in the hole, need lift the tunnel axis of riser position as far as possible, the weak stratum of needs to be buried underground into at the tunnel top, and the buried depth can not be too big, avoids being difficult to the jacking because stratum side resistance or end resistance are too big. And the tunnel vault is arranged in a weak stratum and buried deep and shallow, which brings about two important problems: firstly, the risk of cover layer puncture is easy to occur during shield construction, which is unfavorable for construction safety; secondly, the cover layer is thin during operation, so that the system can be damaged by the risks of upper anchorage, ship sinking and the like. After the method is adopted, the main tunnel can be buried deeply into a hard stable stratum, and the resistance during jacking is reduced by replacing the undisturbed stratum, so that the vertical jacking operation is smoothly realized.

Fourth, the stability of the extraction/drainage stand pipe can be increased. Traditional vertical jacking technology, because of the construction needs, the riser all need set up in weak stratum, and this is all unfavorable to the anti wave power of riser later stage, antidetonation stability. After the method is applied, the vertical pipe can be arranged in relatively stable hard soil and rock stratum, and the stability of the vertical pipe during operation is greatly improved.

Drawings

FIG. 1 is a schematic diagram of an offshore construction platform and a drill steel casing;

FIG. 2 is a schematic view of using fine sand to displace undisturbed formation while capping a temporary closure;

FIG. 3 is a schematic view of the jacking of a riser section by section out of the mud surface in the main tunnel;

FIG. 4 is a view showing the flange plate connecting the casing and the drain cover.

In the figure, 11 is an upper section of a casing, 12 is a lower section of the casing, 2 is a vertical pipe, 3 is a steel pipe piece, 4 is a jacking sealing cover, 5 is a flushing pipe, 6 is a reinforcing supporting part, 7 is a head sealing cover, 8 is a connecting flange, 9 is a temporary sealing cover, 10 is a construction platform, and 13 is a platform support.

Detailed Description

The invention is further illustrated by the following specific embodiments in conjunction with the accompanying drawings:

the present example was carried out as follows:

firstly, as shown in the attached figure 1, a construction platform 10 is arranged on the sea, and a steel casing is arranged, and the concrete steps are as follows:

the first step is as follows: the position coordinates of each water outlet are accurately positioned in a sea area by combining a design drawing and an offshore measurement technology, an offshore construction platform 10 is erected near a drainage riser according to the design drawing, and the platform bottom needs to be about 1m higher than the sea surface (considering the wave height) in the temporary construction period. The platform supports 13 of the construction platform 10 need to be drilled into a stable formation to ensure stability of the construction platform 10 during the borehole replacement.

The second step is that: the inner diameter of the steel pile casing is about 0.5m larger than the diameter of a drilled hole, and the wall thickness of the steel pile casing is determined according to the seawater corrosion degree and the service life on the basis of considering the stability of the construction period; the steel casing is composed of an upper section and a lower section, and the two sections are connected and fixed through a connecting flange 8. The lower section 12 of the pile casing is buried under the seabed and is subjected to relevant anticorrosion treatment according to a permanent structure.

The third step: and (3) driving the steel casing to a designed elevation through the offshore construction platform 10, wherein the lower section 12 of the casing cannot enter the shield tunneling range and is preferably 1m above the shield vault.

Secondly, as shown in the attached figure 2, the undisturbed stratum is replaced, and the temporary sealing cover 9 is covered, the concrete steps are as follows:

the first step is as follows: utilize construction platform 10 to adopt to strike to bore or dig soon and bore and replace the original state soil layer of jacking scope, the drilling scope needs to be greater than jacking scope area, and the diameter is about 1m, drilling depth to 1m below the main tunnel vault.

The second step is that: and returning the undisturbed stratum out by using the large-proportion slurry of the drilled hole, adjusting the specific gravity of the slurry after the undisturbed stratum is cleaned, and filling fine sand and other materials which are beneficial to jacking into the drilled hole to form a replacement layer.

The third step: and after replacement, detaching the flange interface reserved in the middle of the steel casing, and hanging out the upper section 11 of the casing.

The fourth step: 8 phi 50PVC flushing pipes 5 are pre-buried, and reserved conditions are reserved for later flushing resistance reduction and grouting reinforcement.

The fifth step: in order to prevent the pressure relief risk possibly caused during the later stage of shield tunneling, a temporary sealing cover (made of steel material) is connected and fixed at the top end of the lower section 12 of the casing by a flange plate.

And a sixth step: the main tunnel is constructed by adopting a shield method, a displacement point is used as a target for tunneling by utilizing an accurate navigation system of a shield machine, a special steel pipe piece 3 is arranged in a jacking range, a jacking sealing cover 4 is reserved on the top of the steel pipe piece 3 in advance, and the jacking sealing cover 4 is connected with the steel pipe piece 3 through bolts.

Thirdly, as shown in the attached figure 3, the vertical pipe 2 is jacked out of the mud surface section by section in the main tunnel, and the concrete steps are as follows:

the first step is as follows: for preventing that main tunnel bottom stratum counter force is not enough during the jacking, carry out the slip casting to the tunnel bottom and consolidate, form and consolidate supporting part 6.

The second step is that: the temporary cover 9 at the top of the lower casing section 12 is disassembled.

The third step: and (3) erecting a jacking reaction frame and installing a vertical jacking sealing water stop system on the reinforcing support part 6 in the main tunnel.

The fourth step: and connecting the first section of the vertical pipe 2 with the jacking sealing cover 4 on the steel pipe sheet 3, performing jacking test according to the calculated jacking force, checking a waterproof device and the like.

The fifth step: the vertical pipe 2 is ejected section by section, and high-pressure flushing resistance reduction can be carried out through the reserved flushing holes 5 if the jacking resistance is too large in the jacking process.

And a sixth step: after the riser 2 is jacked, in order to increase the stability of the riser 2, the peripheral replacement and filling stratum is reinforced by injecting cement slurry into the flush pipes 5 embedded at the periphery of the riser 2.

Fourthly, as shown in the attached figure 4, the steel casing and the head sealing cover are connected, and the method comprises the following specific steps:

the first step is as follows: at the head closing cap 7 of factory prefabricated steel structure, head closing cap 7 belongs to permanent structure, needs to carry out anticorrosive treatment, should adopt anticorrosive lacquer + sacrifice anodic protection piece's scheme to protect.

The second step is that: transporting the head cover 7 to the water outlet at sea, butting the head cover 7 with the lower section of the protective cylinder driven in the early stage, and connecting by adopting 12M 30 high-strength bolts.

The third step: and (3) filling water into the main tunnel, and after the internal and external water pressures are basically balanced, detaching the jacking sealing cover at the top end of the first section of the vertical pipe 2 to form a water taking/discharging loop.

The present invention has been described in detail, and it should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.