LU600839B1 - Combined submerged floating tunnel and installation methodthereof - Google Patents

Abstract

The present invention discloses a combined submerged floating tunnel (SFT), which includes multiple interconnected tunnel tube segments. Its structures includes two or three of the following: pressure-bearing pier, cable-anchored, pontoon. Each tube segment has a GINA waterstop at its tail end, adjacent tube segments are connected end-to-end. At the connection points, a structure is provided, which includes two connecting ear plates mounted on the outer rotating surfaces at both ends. A flexible waterproof sleeve is welded to the outer rotating surfaces at the connection ends of the two tube segments. The structure is determined based on internationally defined sea conditions. The number of sections for each type is determined by the offshore distance, water depth range of the area where the SFT is to be constructed, as well as the length of a single tube segment. It achieves the goals of adapting to complex waters, accommodating navigable zones, reducing costs. (Fig.1)

Description

DESCRIPTION LU600839

COMBINED SUBMERGED FLOATING TUNNEL AND INSTALLATION METHOD

THEREOF

TECHNICAL FIELD

The invention belongs to the technical field of sea-crossing channel engineering, in particular to a combined submerged floating tunnel and installation method thereof.

BACKGROUND

To promote national economic growth and regional coordinated development, how to quickly and safely cross rivers, lakes, and seas is a key issue in transportation construction. At present, bridges remain the primary form of spanning structures.

However, due to their high requirements for the terrain on both sides, bridges cannot be constructed in some steep and dangerous areas. Immersed tunnels, as an emerging spanning structure, are highly susceptible to damage from marine conditions and seismic loads, making them unsuitable for areas with complex sea conditions and frequent earthquakes. The submerged floating tunnel (SFT) is a new type of spanning transportation structure designed to address the challenge of crossing deep and wide waters in the future. Its unique structure can effectively avoid the impact of seismic loads and is suitable for crossing complex sea conditions. By reasonably designing the self-weight of the tunnel segments and utilizing buoyancy and support systems, the SFT can float in water. Since the SFT is completely submerged, it is less affected by adverse natural conditions such as typhoons, heavy snow, and thick fog, does not interfere with ship navigation, ensures safe and stable passage, and minimizes the environmental impact of construction.

Submerged floating tunnels can be categorized into three types based on different anchoring methods: pressure-bearing pier-type SFTs, cable-anchored SFTs, and pontoon-type SFTs. The pressure-bearing pier-type SFT is suitable for shallow waters (within 50 m). Due to the use of pressure-bearing piers as support structures, it offers excellent stability. However, construction becomes significantly more challenging as water depth increases. The cable-anchored SFT is suitable for medium-depth waters (50-200 m) and can adapt to earthquake-prone areas and harsh seabed conditions.

However, in rough sea conditions with strong winds and waves, the overall stability PÎ600839 the tunnel is poor, and vibrations are easily induced. The pontoon-type SFT is suitable for deep waters (over 200 m). As water depth increases, the construction and maintenance costs change very little, making it highly economical. However, in rough sea conditions, the pontoons are significantly affected, leading to large lateral displacements of the tunnel. Additionally, the presence of pontoon structures can interfere with ship navigation, making pontoon-type SFTs unsuitable for navigable sea areas. Currently, SFT designs are limited to single forms, which are only suitable for relatively simple sea conditions and cannot meet the requirements of deep waters, wide areas, or navigable zones. They also face challenges such as high construction difficulty and expensive costs. At present, there is no complete technical process for the installation of SFTs, and most methods are borrowed from the installation of immersed tunnels. However, the installation methods for immersed tunnels heavily rely on seabed preparation and are not suitable for the floating installation of combined SFTs.

SUMMARY

In response to the aforementioned existing technologies, the present invention provides a combined submerged floating tunnel (SFT) designed for areas with complex water environments, large tunnel spans, and significant variations in offshore water depth and geological conditions. By adopting a combined SFT, the advantages of multiple tunnel forms can be effectively integrated, enhancing adaptability to diverse water environments. This approach is suitable for regions with large tunnel spans, significant variations in offshore water depth, and geological conditions, reducing construction difficulty and costs. Consequently, it achieves the goals of adapting to complex waters, navigable zones, and cost reduction.

To address the technical issues mentioned above, the combined SFT proposed by the present invention includes multiple interconnected tunnel tube segments. These segments include two or three of the following structures: pressure-bearing pier segment tubes, cable-anchored segment tubes, and pontoon segment tubes. Each tube segment has a GINA waterstop at its tail end, and adjacent tube segments are connected end-to-end. At the connection points, a connection structure is provided, which includes two connecting ear plates mounted on the outer rotating surfaces at both ends of each tube segment. Adjacent tube segments are tensioned by two pairs of connecting prestressed steel cables through the ear plates.

A flexible waterproof sleeve is connected to the outer rotating surfaces at tha/600839 connection ends of the two tube segments. The structure of the multiple tunnel tube segments is determined based on internationally defined sea conditions. Each type of tube segment has a single-section length of 200 m, and the number of sections for each type is determined by the offshore distance and water depth range of the area where the SFT is to be constructed, as well as the length of the single section.

Further details of the combined SFT according to the present invention are as follows: the construction of the pressure-bearing pier follows the port engineering pile foundation specifications (JYJ245-98). The ends of the tube passing through the pressure-bearing pier extend at least 1 meter beyond the sides of the pier.

The two connecting ear plates on the outer rotating surfaces at both ends of each tube segment are distributed at 180° circumferentially. The radial distance between the through-holes on the ear plates is greater than the outer diameter of the flexible waterproof sleeve. The flexible waterproof sleeve consists of two semi-circular hoops that are clasped together. The axial dimension of the sleeve is greater than the width of the GINA waterstop but less than the axial distance between the two connecting ear plates on adjacent tube segments.

The connection between adjacent tube segments is achieved as follows: After fixing the two tube segments end-to-end, the connecting prestressed steel cables between them are tensioned to a pre-tensioned state using a jack. During the tensioning process, the GINA waterstop is compressed to ensure watertightness at the joint. Then, the two semi-circular hoops are welded together in a clasped manner on the outer rotating surfaces at the joint to achieve overall reinforcement and sealing.

Sea conditions include different offshore water depth ranges, seabed conditions, and seismic activity frequency under the annual average sea condition level. Based on these sea conditions, the types of structures included in the multiple tunnel tube segments and their arrangement are determined as follows:

Situation 1: Annual average sea condition level of 1-3: 1-1) offshore water depth within 50 m, with seabed conditions of soft clay or hard rock foundations: if the area is earthquake-prone, the structure of the multiple tube segments is cable-anchored segment tubes; if not, it is pressure-bearing pier segment tubes;

1-2) offshore water depth between 50-200 m, with seabed conditions of soft clay Pls00839 hard rock foundations, regardless of seismic activity: the structure of the multiple tube segments is cable-anchored segment tubes; 1-3) offshore water depth over 200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity: the structure of the multiple tube segments is pontoon segment tubes.

Situation 2: Annual average sea condition level of 3-6, including: 2-1) Offshore water depth within 50 m, with seabed conditions of soft clay or hard rock foundations: if the area is earthquake-prone, the structure of the multiple tube segments is cable-anchored segment tubes; if not, it is pressure-bearing pier segment tubes; 2-2) offshore water depth between 50-200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity: the structure of the multiple tube segments is cable-anchored segment tubes; 2-3) offshore water depth over 200 m, with seabed conditions of soft clay or hard rock foundations: if the area is earthquake-prone, the structure of the multiple tube segments is pontoon segment tubes; if not, it is cable-anchored segment tubes.

Situation 3: Annual average sea condition level of 6-9, including: 3-1) offshore water depth within 50 m, with seabed conditions of soft clay or hard rock foundations: if the area is earthquake-prone, the structure of the multiple tube segments is cable-anchored segment tubes; if not, it is pressure-bearing pier segment tubes; 3-2) offshore water depth between 50-200 m: if the seabed conditions are soft clay, regardless of seismic activity, the structure of the multiple tube segments is cable- anchored segment tubes; if the seabed conditions are hard rock, regardless of seismic activity, the structure is pressure-bearing pier segment tubes; 3-3) Offshore water depth over 200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity: the structure of the multiple tube segments is cable-anchored segment tubes.

Compared with the prior art, the invention has the beneficial effects that: by combining multiple structural forms of submerged floating tunnels (SFTs), the construction of SFTs becomes adaptable to more complex water environments, reducing construction difficulty and costs. This enhances the applicability and broadens the prospects for widespread adoption of SFTs. In Shallow Waters (within 50 m):

the pressure-bearing pier segment tubes are selected for ease of construction and, 600839 maintenance. They provide excellent stability and can offer longitudinal stiffness to tube segments in deeper waters, minimizing lateral displacement of the tunnel tubes during storms. In Medium-Depth Waters (50-200 m) or earthquake-prone areas with harsh seabed conditions: the cable-anchored segment tubes are chosen. Seismic loads that would directly act on the tunnel structure are buffered by the anchor cables. Compared to traditional transportation structures, this design offers better shock absorption, energy dissipation, and vibration reduction. Additionally, the water space above the tube segments can serve as a navigation channel for ships, facilitating the three-dimensional utilization of marine space. In Deep Waters (over 200 m): the pontoon segment tubes are selected, effectively reducing the steep increase in construction and maintenance costs with depth. Since only part of the tunnel uses pontoon segment tubes, the overall motion performance and stability are superior to those of a single-form SFT design.

Moreover, if certain tube segments are damaged, the differing tunnel forms prevent a chain reaction of damage throughout the entire tunnel. The combination of multiple SFT structural forms is suitable for waters with significant depth variations and large spans. It offers excellent motion performance and stability while maintaining lower costs. The flexible structural forms adapt to different water environments, overcoming technical challenges in installation and maintenance, and providing significant practical value.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is a schematic diagram of the structure of the combined submerged floating tunnel according to the present invention;

Fig. 2 is an axial view of the combined submerged floating tunnel shown in Figure 1;

Fig. 3 is an end view of the combined submerged floating tunnel shown in Figure 1;

Fig. 4 is a detailed enlarged view of the joint between the sections of the submerged floating tunnel;

Fig. 5 is a schematic diagram of the transportation and installation of the pressure- bearing pier segment tube and the buoyancy segment tube;

Fig. 6 is a schematic diagram of the transportation and installation of the anchor cable segment tube;

Figs. 7-1, 7-2, 7-3, and 7-4 are simplified schematic diagrams of the design schemes of four embodiments of the present invention.

In the figures: LU600839 1. Pressure-bearing pier segment tube; 2. Cable-anchored segment tube; 3.

Pontoon segment tube; 4. Flexible waterproof sleeve; 5. Pressure-bearing pier; 6.

Multiple inclined cables; 7. Cable saddle; 8. Anchor cable base; 9. Mooring anchor cable; 10. Anchoring foundation; 11. Pontoon; 12. Pontoon mooring cable; 13. GINA waterstop; 14. Connecting prestressed steel cable; 15. High-strength fiber cable; 16.

Tube annular buckle; 17. Arc-shaped installation buoyancy tank; 18. Water inlet; 19.

Water outlet; 20. Hydraulic drainage device; 21. Underwater positioning and signal transmission device; 22. Rectangular installation buoyancy tank.

DESCRIPTION OF THE INVENTION

Below, the invention is further explained in conjunction with the accompanying drawings and specific embodiments. However, these embodiments are not intended to limit the scope of the invention in any way.

As shown in Figs. 1, 2, and 3, the combined submerged floating tunnel (SFT) proposed by the present invention includes multiple interconnected tunnel tube segments. The structures of these tube segments include two or three of the following: pressure-bearing pier segment tubes 1, cable-anchored segment tubes 2, and pontoon segment tubes 3.

The pressure-bearing pier segment tubes 1 can be used in shallow waters with relatively gentle seabed and good soil quality, the pressure-bearing pier segment tubes 1 are supported and fixed by pressure-bearing piers 5 and several inclined cables 6.

Both the pressure-bearing pier segment tubes 1 and the pressure-bearing piers 5 are constructed using poured concrete. Pressure-bearing piers 5 are installed at regular intervals to provide longitudinal and lateral stability to the SFT. The inclined cables 6 are pre-tensioned and connect the pressure-bearing pier segment tubes 1 to the sides of the pressure-bearing piers 5. The pressure-bearing pier segment tubes 1 are made of materials denser than water, and the through-type pressure-bearing piers 5 provide support to the tubes, enhancing the overall structural stability of the tunnel. The inclined cables 6 on both sides of the pressure-bearing piers 5 improve the stability of the tube segments, reduce vibrations, and ensure smooth passage for vehicles inside. In this invention, the construction of the pressure-bearing piers 5 follows the port engineering pile foundation specifications (JYJ245-98).

The ends of the tube passing through the pressure-bearing piers extend at least 500839 m beyond the sides of the piers, as shown in Figs. 1 and 2.

The cable-anchored segment tubes 2 are suitable for medium-depth waters with rapid currents and harsher sea conditions. The cable-anchored segment tubes 2 are fixed using cable saddles 7, anchor cable bases 8, mooring anchor cables 9, and anchoring foundations 10. The tube segments are constructed using poured concrete in sections. Anchoring foundations 10 are installed on the seabed at regular intervals.

Several mooring anchor cables 9 are connected at the top to the anchor cable bases 8 fixed on the cable saddles 7 at the top of the tube segments, and at the bottom to the corresponding anchoring foundations 10, with pre-tension applied in advance. The cable-anchored segment tubes 2 are made of materials less dense than water. The top of the tube segments is equipped with cable saddles 7, which are made of stainless steel and welded into U-shaped anchoring steel bars inserted into the SFT tubes. The size of the cable saddles 7 is determined based on the anchoring tension force and safety factors, considering the diameter of the anchor cables. The connection between the cable saddles 7 and the mooring anchor cables 9 is secured by anchor cable bases 8, which are fixed to the cable-anchored segment tubes 2 via pre-embedded anchor bolts. After the mooring anchor cables 9 are fixed to the anchor cable bases 8, protective measures are applied to the connection points, and a sealing cover is used for sealing. The other end of the mooring anchor cables 9 is connected to the anchoring foundations 10. During construction, one end of the mooring anchor cables 9 is first installed on the anchoring foundations 10, and the other end is passed through the anchor cable bases 8. A jack is then used to tension the mooring anchor cables 9 to the designed force before final fixation.

The pontoon segment tubes 3 are suitable for deep waters with calm currents, minimal waves and floating ice, and low navigation traffic. The pontoon segment tubes 3 are constructed using poured concrete in sections. Pontoons 11 are installed at regular intervals. Several pontoon mooring cables 12 connect the pontoons 11 to the pontoon segment tubes 3. The pontoon segment tubes 3 are made of materials denser than water. The pontoons 11 float on the water surface and are connected to the pontoon segment tubes 3 via the pontoon mooring cables 12, ensuring the tunnel floats and remains stable. To prevent corrosion from the marine environment, the surface of the pontoons 11 is coated with a polyurethane anti-corrosion layer.

Each tube segment has a GINA waterstop 13 at its tail end. Adjacent tube 500839 segments are connected end-to-end, with a connection structure at the joint. The connection structure includes two connecting ear plates mounted on the outer rotating surfaces at both ends of each tube segment. Adjacent tube segments are tensioned by two pairs of connecting prestressed steel cables 14 through the ear plates. These prestressed steel cables 14 are used to tension the two tube segments, achieving a flexible connection that enhances the motion performance of the SFT. A flexible waterproof sleeve 4 is installed on the outer rotating surfaces at the connection ends of the two tube segments. The flexible waterproof sleeve 4 is a circular metal-rubber composite plate, with stainless steel as the base material and rubber gaskets for multi- segment connections. Both the inner and outer sides are coated with a polyurethane anti-corrosion layer and sealed for waterproofing. The axial compression of the flexible waterproof sleeve 4 provides secondary protection for the connection between different tube segments. The GINA waterstop 13 ensures watertightness, preventing seawater ingress. In the present invention, the two connecting ear plates on the outer rotating surfaces at both ends of each tube segment are distributed at 180° circumferentially.

The radial distance between the through-holes on the ear plates is greater than the outer diameter of the flexible waterproof sleeve 4.

The flexible waterproof sleeve 4 is used for connecting different tube segments of the SFT. In the embodiment of the invention, the flexible waterproof sleeve 4 is a circular steel tube with dimensions matching the SFT tube segments. For ease of installation, the flexible waterproof sleeve 4 is divided into two semi-circular hoops that are clasped together. The axial dimension of the sleeve is greater than the width of the

GINA waterstop 13 but less than the axial distance between the two connecting ear plates on adjacent tube segments. As shown in Figs. 3 and 4, the connection process between adjacent tube segments is as follows: After fixing the two tube segments end- to-end, the connecting prestressed steel cables 14 between them are tensioned to a pre-tensioned state using a jack. During the tensioning process, the GINA waterstop 13 is compressed to ensure watertightness at the joint. The two semi-circular hoops are then welded together in a clasped manner, and the flexible waterproof sleeve 4 is spot- welded to the outer surfaces of the adjacent tube segments. If the connecting prestressed steel cables 14 need to be re-tensioned during use, the flexible waterproof sleeve 4 can undergo axial compression, continuing to provide secondary protection to the internal GINA waterstop 13.

The structure of the multiple tunnel tube segments is determined based MN, 600839 internationally defined sea conditions, including the annual average sea condition level, offshore water depth range, seabed conditions, and seismic activity frequency. The types of structures included in the multiple tunnel tube segments and their arrangement are determined according to the sea conditions, as shown in Table 1.

Table 1. Form of combined suspension tunnel and corresponding sea conditions

Annual Are

Offshore Seabed average sea _ earthquakes Tube type water depth conditions level frequent

Cable-

Yes anchored

Soft clay segment tube foundation Pressure- bearing pier

Within 50 segment tube m Cable-

Yes anchored

Hard reef segment tube foundation Pressure-

Level 1-3 bearing pier (Wave segment tube height >1.25 m)

Cable-

Yes anchored

Soft clay segment tube foundation Cable- m-200 anchored m segment tube

Cable-

Hard reef Yes anchored foundation segment tube je | ee

Annual Are

Offshore Seabed LUB00839 average sea _ earthquakes Tube type water depth conditions level frequent anchored segment tube

Pontoon

Yes

Soft clay segment tube foundation Pontoon

Over 200 segment tube m Pontoon

Yes

Hard reef segment tube foundation Pontoon segment tube

Cable-

Yes anchored

Soft clay segment tube foundation Pressure- bearing pier

Within 50 segment tube m Cable-

Yes anchored

Hard reef segment tube

Level 3-6 foundation Pressure- (Wave bearing pier height 1.25 m-6 segment tube m

Cable-

Yes anchored

Soft clay segment tube foundation Cable- m-200 anchored m segment tube

Cable-

Hard reef

Yes anchored foundation segment tube

Annual Are

Offshore Seabed LUB00839 average sea _ earthquakes Tube type water depth conditions level frequent

Cable- anchored segment tube

Pontoon

Yes segment tube

Soft clay

Cable- foundation anchored

Over 200 segment tube m Pontoon

Yes segment tube

Hard reef . Cable- foundation anchored segment tube

Cable-

Yes anchored

Soft clay segment tube foundation Pressure- bearing pier

Within 50 segment tube m Cable-

Level 6-9 Yes anchored (Wave Hard reef segment tube height over 6 foundation Pressure- m) bearing pier segment tube

Cable-

Yes anchored m-200 Soft clay segment tube m foundation

Cable- anchored

Annual Offshore Seabed Are LUB00839 average sea _ earthquakes Tube type

DE ET ee |e ee

Pressure-

Yes bearing pier

Hard reef segment tube foundation Pressure- bearing pier segment tube

Cable-

Yes anchored

Soft clay segment tube foundation Cable- anchored

Over 200 segment tube m Cable-

Yes anchored

Hard reef segment tube foundation Cable- anchored segment tube

Based on the determination of the tube segment structures shown in Table 1, the overall structure of the combined submerged floating tunnel (SFT) is further determined by considering the span of the tunnel, the offshore distance of the water depth range, and the length of a single tube segment. In this invention, the length of a single tube segment for each structure is 200 m.

Embodiment 1 LU600839

With a span of 15 km and a water depth of 50 m, the annual average sea level is

Grade 1-3, and the distance between both sides of the shore is 5 km.

The seabed is a hard reef foundation and there is no earthquake. The annual average sea state in the water depth range of 50 m-100 m is Grade 3-6, and the distance between the offshore sides is 10 km. The seabed is a hard reef foundation without earthquake. In view of the above sea conditions, the multi-section tunnel tube body in Embodiment 1 includes 50 pressure-bearing pier segment tubes and 25 cable- anchored segment tubes, and the connection sequence of all tubes is 25 pressure- bearing pier segment tubes -25 cable-anchored segment tubes -25 pressure-bearing pier segment tubes, as shown in Fig. 7-1.

Embodiment 2

With a span of 15 km and a water depth of 50 m, the annual average sea level is

Grade 1-3, and the distance between both sides of the shore is 5 km. The seabed is a hard reef foundation and there is no earthquake. When the span is 15 km, the water depth at the place where the water depth exceeds 50 m suddenly increases by more than 200 m, the average sea state in the range is 3-6, and the distance between the two sides offshore is 10 km. The seabed is a hard reef foundation without earthquake. In view of the above sea conditions, the multi-section tunnel tube body in Embodiment 2 includes 50 pressure-bearing pier segment tubes and 25 pontoon segment tubes, and the connection sequence of all tubes is 25 pressure-bearing pier segment tubes -25 pontoon segment tubes -25 pressure-bearing pier segment tubes, as shown in Fig. 7-2.

Embodiment 3

With a span of 30 km and a water depth of 50 m, the annual average sea level is

Grade 1-3, and the distance between both sides of the shore is 5 km. The seabed is a hard reef foundation and there is no earthquake. The annual average sea state at the water depth of 50 m-200 m is Grade 1-3, and the distance between the offshore sides is km. The seabed is a hard reef foundation with frequent earthquakes. The annual average sea state at the water depth of more than 200 m is 3-6, and the distance between the offshore sides is 15 km.

The seabed is a hard reef foundation and earthquakes are frequent. In view of Ne 600839 above sea conditions, the multi-section tunnel tube body in Embodiment 3 includes 50 pressure-bearing pier segment tubes, 50 cable-anchored segment tubes and 50 pontoon segment tubes, and the connection sequence of all tubes is 25 pressure- bearing pier segment tubes -25 pontoon segment tubes- 50 cable-anchored segment tubes-25 pontoon segment tubes -25 pressure-bearing pier segment tubes, as shown in

Fig. 7-3.

Embodiment 4

When the span is 20 km, the annual average sea state level within 50 m is Grade 1-3, and the offshore distance on one side is 2 km, and the seabed is hard reef foundation without earthquake, and the offshore distance on the other side is 10 km, and the seabed is hard reef foundation without earthquake. When the water depth exceeds 50 m, the water depth suddenly increases to more than 200 m, the annual average sea state grade is 3-6, and the distance from the offshore side is 10 km. The seabed is a hard reef foundation and earthquakes are frequent. The water depth is gradually shallow from 50 m-200 m, the annual average sea level is Grade 3-6, the distance from the offshore side is 15 km, and the seabed is a hard reef foundation with frequent earthquakes. In view of the above sea conditions, the multi-section tunnel tube body in Embodiment 4 includes 35 pressure-bearing pier segment tubes, 25 cable- anchored segment tubes and 40 pontoon segment tubes, and the connection sequence of all tubes is 10 pressure-bearing pier segment tubes -40 pontoon segment tubes- 25 cable-anchored segment tubes -25 pressure-bearing pier segment tubes, as shown in

Fig. 7-4.

Embodiment 5

If the tunnel span exceeds 3,000 m, the construction of a combined SFT should be considered, and the structural design should follow the design approach shown in Table 1. This embodiment proposes a transportation device for the tube segments (but is not limited to this device), mainly including arc-shaped installation pontoons 17 and rectangular installation pontoons 22, where arc-shaped installation pontoons 17 are used for transporting pressure-bearing pier segment tubes 1 and pontoon segment tubes 3. The pontoons are towed by installation vessels to the designated location.

The side of the pontoons is equipped with a water inlet 18, and the bottom 1$1600839 equipped with a water outlet 19. The internal hydraulic drainage device 20 controls the descent of the tube segments to the specified depth through the water inlet 18 and enables the pontoons to float for reuse through the water outlet 19 and hydraulic drainage device 20. The rectangular installation pontoons 22 are used for transporting cable-anchored segment tubes 2. The working principle is similar to that of the arc- shaped installation pontoons 17, allowing for controlled descent and reuse, as shown in

Figs. 5 and 6.

And install according to the following steps:

Step 1: first divide the tube segment forms and combinations for the SFT construction area according to the following standards.

The length of each combined SFT tube segment is 200 m. Determine the structure of the multiple tunnel tube segments based on internationally defined sea conditions, offshore water depth variations, seabed conditions, and seismic activity frequency.

Determine the number of tube segments based on the offshore distance of the water depth range and the length of a single tube segment. In Table 2, Y1 and Y2 represent pressure-bearing pier segment tubes; M, M1, and M2 represent cable- anchored segment tubes; and F represents pontoon segment tubes. Table 2 shows the tube segment structure combinations for Embodiments 1 to 4.

Table 2. Embodiment 1-4 of Combined Suspension Tunnel sequence

When the span is 15 Y1 (25 sections)- M(25 km, the annual average sea level within 50 m is Grade 1-3, the offshore distance is Pressure-bearing pier km, the seabed is a hard | segment tube reef foundation with no Cable-anchored See Fig. 7-1 for the schematic diagram of earthquake. The average | segment tube sea state in the range of 50 Embodiment 1 m-100 m water depth is

Grade 3-6, and the sequence distance from the shore to the seabed is 10 km, with no earthquake.

When the span is 15 Y1 (25 sections)- F(25 km, the annual average sea level within 50 m is Grade 1-3, the offshore distance is 5km, the seabed is a hard reef foundation with no earthquake. When the water depth exceeds 50 m, Pressure-bearing pier segment tube See Fig. 7-2 for the the water depth suddenly creases to more than 200 Pontoon segment tube | schematic diagram of m, the average sea state in Embodiment 2 the range is Grade 3-6, the offshore distance is 10 km, and the seabed is a hard reef foundation with no earthquake.

When the span is 30 Y1 (25 sections)- km, the annual average sea M1(25 sections)- F(50 level within 50 m is Grade sections)- M2(25 sections)- 1-3, and the offshore Y2(25 sections) distance is 5 km. The Pressure-bearing pier seabed is a hard reef segment tube foundation with no Cable-anchored earthquake. The annual | segment tube See Fig. 7-3 for the average sea state at the Pontoon segment tube | schematic diagram of water depth of 50 m-200 m Embodiment 3 is Grade 1-3, and the offshore distance is 10 km.

The seabed is a hard reef sequence foundation with frequent earthquakes. When the water depth exceeds 200 m, the annual average sea level is Grade 3-6, and the offshore distance is 15 km.

The seabed is a hard reef foundation with frequent earthquakes.

When the span is 20 Y1 (10 sections)- F(40 km, the annual average sea sections)- M(25 sections)- state within 50 m of water Y2(25 sections) depth is Grade 1-3, and the offshore distance is 2 km.

The seabed is hard reef foundation with no earthquake, and the other side is 10 km offshore, and the seabed is hard reef Pressure-bearing pier foundation with no | segment tube earthquake. When the Cable-anchored . water depth exceeds 50 m, | segment tube See Fig. 75 for the the water depth suddenly Pontoon segment tube schematic diagram of increases to more than 200 Embodiment 4 m, the annual average sea state grade is Grade 3-6, and the offshore distance is km. The seabed is a hard reef foundation with frequent earthquakes. The water depth is gradually shallow from 50 m to 200 sequence m, the annual average sea level is Grade 3-6, and the offshore distance is 15km.

The seabed is a hard reef foundation with frequent earthquakes.

Step 2: construction of various tube segments in the dry dock .The construction of the pressure-bearing pier segment tubes 1 and pontoon segment tubes 3 can be carried out simultaneously. In the dry dock, the internal reinforcement framework of the tube segments is first completed, and multiple outer concrete casting molds are prepared based on the reinforcement. The required concrete density is calculated based on the buoyancy and gravity of the tube segments. Both types of tube segments can use the same concrete mixture for casting, following the construction process specified in the immersed tunnel design code (GB/T 51318-2019). For the pressure-bearing pier segment tubes 1 and pontoon segment tubes 3, tube annular buckles 16 are installed at m intervals on the top. Arc-shaped installation pontoons 17 are installed at the bottom of the tube segments using cranes. High-strength composite fiber cables 15 are used to secure the arc-shaped installation pontoons 17 to the pressure-bearing pier segment tubes 1 via the tube annular buckles 16. The construction of the cable- anchored segment tubes 2 is carried out separately. In the dry dock, the internal reinforcement framework is completed, and multiple outer concrete casting molds are prepared based on the reinforcement. Lightweight aggregate concrete is used to ensure that the buoyancy of the tube segments exceeds their gravity. After the tube segments are constructed, cable saddles 7 are installed at the center of the segments, and the arc-shaped installation pontoons 17 are connected to the cable saddles 7 using high- strength fiber cables 15. Tube annular buckles 16 are installed at 10 m intervals on both sides of the cable saddles 7.

Step 3: GINA waterstops 13 are installed at the tail ends of each tube segment, and 500839 steel doors are used to seal both ends of the tube segments to ensure watertightness, completing the primary outfitting. The dry dock is then flooded until the tube segments float. Tugboats and installation vessels enter the dry dock, and universal underwater positioning devices and signal receivers 21 are installed on both sides of the tube segments. Connecting ear plates for the prestressed steel cables 14 are bolted to the central axis positions on the upper and lower walls of both ends of the tube segments, and the required steel cables are connected at the tail ends. This completes the secondary outfitting of the tube segments.

Step 4: for Embodiment 1, the following installation method is adopted: first the pressure-bearing pier segment tubes 1 are transported to the designated location using tugboats and installation vessels.

Underwater installation vessels connect the tube annular buckles 16 to the cranes on the deck using high-strength fiber cables 15. The arc-shaped installation pontoons 17 at the bottom are opened at the water inlets 18, allowing the tube segments to gradually descend. Based on signals from the underwater positioning and signal transmission devices 21, the water inlets 18 are closed once the tube segments reach the specified depth. The cranes' mechanical arms are used to align the tube segments horizontally. Divers disconnect the high-strength fiber cables 15 between the pressure- bearing pier segment tubes 1 and the arc-shaped installation pontoons 17. The water outlets 19 are opened, and the internal seawater is drained using hydraulic devices 20, allowing the pontoons to float for reuse. After fixing the adjacent tube segments, the connecting prestressed steel cables 14 are tensioned to the pre-tensioned state using jacks. During this process, the GINA waterstops 13 at the ends of the tube segments are compressed to ensure watertightness. The flexible waterproof sleeves 4 are then used for overall reinforcement and sealing. The construction of the pressure-bearing piers follows the port engineering pile foundation specifications (JYJ245-98). The tube segments passing through the pressure-bearing piers are shorter, with each end extending 1 m to connect to the next tube segment. After completing the installation of the pressure-bearing pier segment tubes 1, the cable-anchored segment tubes 2 are transported and installed. Tugboats and installation vessels are directly connected to the cable saddles 7 of the cable-anchored segment tubes 2 and transported to the designated location. Underwater installation vessels connect the tube annular buckles 16 to the cranes on the deck using high-strength fiber cables 15.

The structural form of the cable-anchored segment tubes 2 of the anchor cable’600839 section when it is connected with the crane during installation is shown in Fig. 6. The water inlets 18 of the rectangular installation pontoons 22 connected with the cable saddles 7 is opened at the same time, so that the tube body gradually descends.

Through the underwater positioning and the signal feedback display of the signal transmission devices 21, after descending to the specified depth, the water inlets 19 of the rectangular installation pontoons 22 on both sides are closed, and the horizontal docking of the tube sections is completed by using the mechanical arm of the crane.

Divers disconnect the high-strength fiber cables 15 between the cable saddles 7 and the rectangular installation pontoons 22.

The water outlets 19 are opened, and the internal seawater is drained using hydraulic devices 20, allowing the pontoons to float. After fixing the adjacent tube segments, the connecting prestressed steel cables 14 are tensioned to the pre- tensioned state using jacks. During this process, the GINA waterstops 13 at the ends of the tube segments are compressed to ensure watertightness. The flexible waterproof sleeves 4 are then used for overall reinforcement and sealing. The connection prestressed steel cable at the connection between the cable-anchored segment tubes 2 of the anchor cable section and the pressure-bearing pier segment tubes 1 of the pressure-bearing pier section should be slightly less than the tension of the same type of tube body connection. The width of the GINA waterstops 13 should be slightly larger than that of the same type of tube segment connections. The width of the flexible waterproof sleeves 4 should be twice that of the same type of tube segment connections (typically 0.5 m) to ensure flexible connections, allow some displacement, and prevent joint damage. The installation sequence is Y1-Y2-M.

For Embodiment 2, the installation method is as follows: first the installation method for the pressure-bearing pier segment tubes 1 is the same as in Embodiment 1. After completing the installation of the pressure-bearing pier segment tubes 1, proceed with the installation of the pontoon segment tubes 3. Transport the pontoon segment tubes 3 to the designated location using tugboats and installation vessels. Install pontoon mooring cables 12 on the water surface and connect them to the pontoons 11.

Underwater installation vessels connect the tube annular buckles 16 to the cranes on the deck using high-strength fiber cables 15.

Open the water inlets 18 of the arc-shaped installation pontoons 17 at the bottom 500839 to allow the tube segments to gradually descend. Based on signals from the underwater positioning and signal transmission devices 21, close the water inlets 18 once the tube segments reach the specified depth. Divers disconnect the high-strength fiber cables 15 between the tube annular buckles 16 and the arc-shaped installation pontoons 17.

Open the water outlets 19 and drain the internal seawater using the hydraulic devices 20, allowing the arc-shaped installation pontoons 17 to float. Reduce the pre-tension on the cranes' mechanical arms until the pontoon segment tubes 3 stabilize. Adjust the length of the pontoon mooring cables 13 using jacks until the pontoon segment tubes 3 reach the designated installation position. Use the cranes' mechanical arms to align the tube segments horizontally.

After fixing the adjacent tube segments, tension the connecting prestressed steel cables 14 on the tube walls using jacks to achieve the pre-tensioned state. During this process, compress the GINA waterstops 13 at the ends of the tube segments to ensure watertightness. Then, use the flexible waterproof sleeves 4 for overall reinforcement and sealing. The installation sequence is Y1—Y2—F.

For Embodiment 3, the installation method is as follows: first the installation method for the pressure-bearing pier segment tubes 1 and cable-anchored segment tubes 2 is the same as in Embodiment 1. The installation method for the pontoon segment tubes 3 is the same as in Embodiment 2. Compared to Embodiment 2, the lateral displacement at the connection between the cable-anchored segment tubes 2 and the pontoon segment tubes 3 is greater. Therefore, the tension of the connecting prestressed steel cables 14 at this joint should be slightly less than that in Embodiment 2. The size of the

GINA waterstops 13 should be slightly larger than that in Embodiment 2. The width of the flexible waterproof sleeves 4 should be four times that of the same tube segment joints to ensure sufficient flexibility, watertightness, and prevent joint damage. The installation sequence is Y1—Y2—M1—M2—F.

For Embodiment 4, the installation method is as follows: first the installation method for the pressure-bearing pier segment tubes 1 and cable-anchored segment tubes 2 is the same as in Embodiment 1. The installation method for the pontoon segment tubes 3 is the same as in Embodiment 2. The installation method for the connection parts is the same as in Embodiments 2 and 3.

The installation sequence is Y1—Y2—M—F. LU600839

Step 5: After completing the installation of the tube segments: remove the installation equipment, including the tube annular buckles 16 and underwater positioning and signal transmission devices 21.

Conduct watertightness testing to ensure no water enters the tube joints. Once watertightness is confirmed, workers enter the tube segments to remove the waterproof steel doors installed during the primary outfitting. Perform secondary concrete filling and pouring at the road connection points inside the tube segments to ensure a continuous and smooth road surface. Complete the internal electrical primary and secondary designs, after which the tunnel is ready for operation.

Although the invention has been described in detail with reference to the accompanying drawings, it is not limited to the specific embodiments described above.

These embodiments are illustrative rather than restrictive.

Under the guidance of the invention, those skilled in the art can make various modifications without departing from the spirit of the invention, and all such modifications fall within the scope of protection of the invention.

Claims (5)

CLAIMS LU600839

1. A combined submerged floating tunnel (SFT), comprising a plurality of interconnected tunnel tube segments, characterized in that the structures of the multiple tunnel tube segments comprise two or three of the following: pressure-bearing pier segment tubes (1), cable-anchored segment tubes (2), and pontoon segment tubes (3); each tube segment has a GINA waterstop (13) at its tail end, and adjacent tube segments are connected end-to-end, at the connection points, a connection structure is provided, the connection structure comprises two connecting ear plates mounted on the outer rotating surfaces at both ends of each tube segment, adjacent tube segments are tensioned by two pairs of connecting prestressed steel cables (14) through the ear plates, a flexible waterproof sleeve (4) is installed on the outer rotating surfaces at the connection ends of the two tube segments; the structure of the tunnel tube segments is determined based on internationally defined sea conditions; the length of a single tube segment for each structure is 200 m; the number of sections for each type of tube segment is determined by the offshore distance and water depth range of the area wherein the SFT is to be constructed, as well as the length of a single tube segment.

2. The combined SFT according to claim 1, characterized in that for the pressure- bearing pier segment tubes (1), the construction of the pressure-bearing piers follows the port engineering pile foundation specifications (JYJ245-98), the ends of the tube passing through the pressure-bearing piers extend at least 1 m beyond the sides of the piers.

3. The combined SFT according to claim 1, characterized in that the two connecting ear plates on the outer rotating surfaces at both ends of each tube segment are distributed at 180° circumferentially; the radial distance between the through-holes on the ear plates is greater than the outer diameter of the flexible waterproof sleeve (4), the flexible waterproof sleeve (4) comprises two semi-circular hoops that are clasped together, the axial dimension of the sleeve is greater than the width of the GINA waterstop (13) but less than the axial distance between the two connecting ear plates on adjacent tube segments.

4. The combined SFT according to claim 3, characterized in that the connection 500839 process between adjacent tube segments is as follows: after fixing the two tube segments end-to-end, the connecting prestressed steel cables (14) between them are tensioned to a pre-tensioned state using a jack, during the tensioning process, the GINA waterstop (13) is compressed to ensure watertightness at the joint, then, the two semi- circular hoops are welded together in a clasped manner on the outer rotating surfaces at the joint to achieve overall reinforcement and sealing.

5. The combined SFT according to claim 1, characterized in that the sea conditions comprise the annual average sea condition level, offshore water depth range, seabed conditions, and seismic activity frequency, based on these sea conditions, the types of structures comprised in the multiple tunnel tube segments and their arrangement are determined as follows: situation 1: annual average sea condition level of 1-3, comprising: 1-1) offshore water depth within 50 m, with seabed conditions of soft clay or hard rock foundations; if the area is earthquake-prone, the structure of the multiple tube segments is cable-anchored segment tubes; if not, it is pressure-bearing pier segment tubes; 1-2) offshore water depth between 50-200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity, the structure of the multiple tube segments is cable-anchored segment tubes; 1-3) offshore water depth over 200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity, the structure of the multiple tube segments is pontoon segment tubes; situation 2: annual average sea condition level of 3-6, comprising: 2-1) offshore water depth within 50 m, with seabed conditions of soft clay or hard rock foundations; if the area is earthquake-prone, the structure of the multiple tube segments is cable-anchored segment tubes; if not, it is pressure-bearing pier segment tubes; 2-2) offshore water depth between 50-200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity, the structure of the multiple tube segments is cable-anchored segment tubes; 2-3) offshore water depth over 200 m, with seabed conditions of soft clay or hard rock foundations; if the area is earthquake-prone, the structure of the multiple tube segments is pontoon segment tubes; if not, it is cable-anchored segment tubes;

situation 3: snnual average sea condition level of 6-9, comprising: LU600839

3-1) offshore water depth within 50 m, with seabed conditions of soft clay or hard rock foundations; if the area is earthquake-prone, the structure of the multiple tube segments is cable-anchored segment tubes; if not, it is pressure-bearing pier segment tubes:

3-2) offshore water depth between 50-200 m, if the seabed conditions are soft clay, regardless of seismic activity, the structure of the multiple tube segments is cable- anchored segment tubes; if the seabed conditions are hard rock, regardless of seismic activity, the structure is pressure-bearing pier segment tubes:

3-3) offshore water depth over 200 m, with seabed conditions of soft clay or hard rock foundations, regardless of seismic activity, the structure of the multiple tube segments is cable-anchored segment tubes.