Receiving sleeve device for tunnel construction equipment

Abstract

The utility model relates to a receiving sleeve device for tunnel construction equipment. The receiving sleeve device is used for receiving a tunneling main machine. The receiving sleeve device is in a container shape, a receiving cavity and a fitting face located at an opening of the receiving cavity are formed in the receiving sleeve device, the fitting face is matched with a connecting face of a tunnel portal, and the receiving sleeve device is connected with the tunnel portal. The receiving sleeve device is provided with a plurality of grouting assemblies distributed at intervals, and the grouting assemblies communicate with the receiving cavity. The receiving sleeve device forms a connecting structure at an equipment receiving tunnel portal, the grouting assembly conducts grouting operation into the device, construction equipment receives under pressure, construction safety is guaranteed, and hidden dangers such as construction settlement caused by pressure loss are prevented. The receiving sleeve device is adjusted according to the position of a tunnel portal and the receiving direction of tunneling equipment, so that the device is flexibly fixed.

Description

Technical Field

[0001] The utility model relates to the technical field of tunnel construction, in particular to a receiving sleeve device for tunnel construction equipment. Background Art

[0002] During the tunnel construction process, the tunneling equipment needs to tunnel through the soil layer on the planned path. Among them, a tunneling sleeve is arranged at the starting end of the tunnel to install the tunneling equipment. A receiving sleeve is installed at the portal at the other end of the tunnel, and the receiving sleeve can receive the tunneling equipment. For example, Chinese published document CN112879022A discloses a method for a tunneling equipment of a tunnel connection passage to enter a hole by means of a flexible sleeve system. The construction steps include, before construction, first carrying out construction preparation, and then carrying out equipment installation and debugging. After the debugging is completed, the main tunnel segment at the starting portal is cut, tunneling is started, the main tunnel segment at the receiving portal is cut, and the tunneling equipment is received. Finally, the receiving portal is sealed. Chinese published document CN219061661U discloses a receiving portal structure for a connection passage, and the receiving portal structure for the connection passage is connected to a shield segment.

[0003] However, the overall weight of the sleeve structure is large. The existing receiving portal uses an external bracing frame to lean against the tunnel wall for support, which is not only complex in structure, but also poor in the sealing cooperation effect between the sleeve structure and the receiving portal, affecting the sealing performance of the sleeve structure. When the tunneling main machine breaks through the tunnel portal, pressure loss is likely to occur, affecting the stability of the tunneling tunnel, and the disturbance to the soil body brings technical problems such as settlement, so improvement is needed. Summary of the Utility Model

[0004] To overcome the problems existing in the related art, an embodiment of the utility model provides a receiving sleeve device for tunnel construction equipment, which is used to solve the technical problems of pressure loss after the tunneling main machine breaks through the tunnel portal and poor sealing between the receiving sleeve and the tunnel portal.

[0005] According to the first aspect of the embodiment of the utility model, a receiving sleeve device for tunnel construction equipment is provided. The receiving sleeve device is used to receive the tunneling main machine. The receiving sleeve device is in a container shape, and the receiving sleeve device forms a receiving cavity and a fitting surface located at the opening of the receiving cavity. The fitting surface is adapted to the connection surface of the tunnel portal, and the receiving sleeve device is connected to the tunnel portal;

[0006] The receiving sleeve device is provided with a plurality of grouting components distributed at intervals, and the grouting components are communicated with the receiving cavity.

[0007] In one embodiment, the receiving sleeve device includes a tubular sleeve assembly and a tail section member that closes one end of the sleeve assembly, and the sleeve assembly and the tail section member are of an integral structure; alternatively, the sleeve assembly and the tail section member are detachably connected, a sealing member is provided at the joint between the sleeve assembly and the tail section member, the fitting surface is provided at the other end of the sleeve assembly, and a plurality of grouting assemblies are spaced apart and distributed on the sleeve assembly.

[0008] In one embodiment, the sleeve assembly includes at least one intermediate section and a connecting section connected to the intermediate section, the fitting surface is provided at the end of the connecting section, and the intermediate section and the tail section member are fixedly connected.

[0009] In one embodiment, the sleeve assembly includes two or more split shells that fit together, and a sealing mechanism is provided at the joint between adjacent shells.

[0010] In one embodiment, a plurality of reinforcing ribs are provided on the outer peripheral wall of the sleeve assembly, and the reinforcing ribs are distributed at the joint.

[0011] In one embodiment, the sealing mechanism includes a gasket or a sealing ring or a plurality of complementary sealing ribs.

[0012] In one embodiment, the cross-section of the sleeve assembly in a direction perpendicular to the center line is circular, rectangular, quasi-rectangular or other cross-sectional shapes adapted to accommodate the tunneling main machine.

[0013] In one embodiment, at least one manhole is provided on the sleeve assembly and / or the tail section member, and a cover assembly is connected to the corresponding manhole, and a sealing member is provided on the joint surface between the cover assembly and the manhole.

[0014] In one embodiment, the receiving sleeve device and the tunnel portal are mechanically connected; alternatively, the receiving sleeve device and the tunnel portal are fixedly connected by welding; alternatively, the receiving sleeve device abuts against the tunnel portal under the jacking action of the preloading mechanism.

[0015] In one embodiment, the fitting surface is set as one of a convex arc surface, a concave arc surface, a plane, a multi-segment plane, and a multi-segment curve.

[0016] The technical solution provided by the embodiment of the present utility model may include the following beneficial effects: The fitting surface can match the connection surface at the tunnel portal, and the tunnel portal can be in any direction such as horizontal, vertical or inclined. The receiving sleeve device is adjusted according to the position of the portal and the receiving direction of the tunneling equipment, so as to realize the flexible fixation of the device. The receiving sleeve device forms a connection at the equipment receiving portal to constitute a sealed receiving body structure. Fillers are arranged in the receiving sleeve device to constitute a pressure maintaining structure, and the tunneling main machine of the construction equipment receives with pressure, ensuring the safety of construction and preventing potential hazards such as construction settlement caused by pressure loss.

[0017] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present utility model. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings herein are incorporated into the specification and form a part of the specification, showing embodiments in accordance with the present utility model, and are used together with the specification to explain the principles of the present utility model.

[0019] Figure 1 is a schematic structural diagram of a receiving sleeve device for a tunnel construction equipment shown according to an embodiment.

[0020] Figure 2 is a schematic cross-sectional view of a receiving sleeve device for a tunnel construction equipment installed at a tunnel portal shown according to an embodiment.

[0021] Figure 3 is a schematic cross-sectional view of a receiving sleeve device for a tunnel construction equipment shown according to an embodiment.

[0022] Figure 4 is Figure 3 an enlarged schematic view of part A in

[0023] Figure 5 is a schematic diagram of a rectangular sleeve assembly shown according to an embodiment.

[0024] Figure 6 is a schematic diagram of a receiving sleeve device for a tunnel construction equipment provided with reinforcing ribs shown according to an embodiment.

[0025] In the figure, tail section member 10; sleeve assembly 20; intermediate section 21; upper half shell 211; lower half shell 212; sealing mechanism 213; connecting section 22; fitting surface 23; grouting assembly 24; personnel access port 25; cover assembly 26; reinforcing rib 27; tunnel portal 30. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams rather than actual pictures, and should not be construed as a limitation on the present utility model; in order to better illustrate the embodiments of the present utility model, some components in the attached drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted.

[0027] In the attached drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if terms such as "upper", "lower", "left", "right", "inner", "outer", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the attached drawings. This is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms used to describe the positional relationship in the attached drawings are only for illustrative purposes and should not be construed as a limitation on the present utility model. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0028] In the description of the present utility model, unless otherwise clearly specified and defined, if terms such as "connection" are used to indicate the connection relationship between components, this term should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0029] As Figures 1 to 3 shown, the present utility model provides a receiving sleeve device for tunnel construction equipment, and the device is used to receive the tunneling main machine. The receiving sleeve device is located at the receiving end of the tunneling main machine, and the tunneling main machine tunnels through the tunnel portal 30 area on the tunnel and enters the receiving sleeve device to complete the tunnel tunneling operation.

[0030] The receiving sleeve device is in the shape of a container. Specifically, the receiving sleeve device is a barrel-shaped structure with one end closed and the other end open. Among them, the receiving sleeve device is formed with a receiving cavity and a fitting surface 23 located at the opening of the receiving cavity. The fitting surface 23 is adapted to the connecting surface of the tunnel portal. The receiving sleeve device is connected to the tunnel portal 30 so as to form a sealed chamber between the receiving cavity and the tunnel portal 30. The receiving sleeve device is connected to the tunnel portal, so that the receiving cavity is in a sealed state, and objects can be filled inside to apply a preset pressure-retaining pressure to the tunnel portal. The fitting surface 23 can match the connecting surface at the tunnel portal 30. The tunnel portal 30 can be in any direction such as horizontal, vertical or inclined. The fitting surface 23 is adjusted according to the position of the portal and the receiving direction of the tunneling equipment, so as to realize the flexible fixation of the device.

[0031] The receiving sleeve device includes a tubular sleeve assembly 20 and a tail section 10 that closes one end of the sleeve assembly 20. The sleeve assembly 20 and the tail section 10 form a split structure. The receiving sleeve device for tunnel construction equipment is assembled in multiple sections or pieces, so as to reduce the assembly weight, and then reduce the construction difficulty and assembly difficulty. The fitting surface 23 is arranged at the other end of the sleeve assembly 20, and the fitting surface 23 is adapted to the connecting surface of the tunnel portal 30.

[0032] As Figures 3 to 6 shown, in an embodiment, the sleeve assembly 20 and the tail section 10 are of an integral structure. For example, the sleeve assembly 20 is connected to the tunnel portal 30, and the tail section 10 is fixed to the sleeve assembly 20 by welding to form an integral structure with good overall sealing performance, and the assembly difficulty is reduced by segmented welding. Or, the sleeve assembly 20 and the tail section 10 are of an integral structure as a whole, and are integrally welded to the tunnel portal 30 for connection, so as to realize overall assembly.

[0033] In another embodiment, the sleeve assembly 20 and the tail section 10 are detachably connected, and a sealing member is arranged at the joint of the sleeve assembly 20 and the tail section 10. The sleeve assembly 20 and the tail section 10 can be locked by a plurality of fasteners to form a detachable connection structure. Optionally, flange rings are fixed at the joint of the sleeve assembly 20 and the tail section 10, and the flange rings are locked and connected by bolt assemblies. Further preferably, the sleeve assembly 20 and the tail section 10 are inserted and matched to improve the tightness of the fitting connection.

[0034] The sealing member is a sealing ring arranged on the sleeve assembly 20 and / or the tail section 10, and the sealing ring seals the joint of the sleeve assembly 20 and the tail section 10. Optionally, the sealing member is a sealing washer, and the sealing washer seals the fitting surface of the sleeve assembly 20 and the tail section 10.

[0035] In one embodiment, the sleeve assembly 20 includes at least one intermediate section 21 and a connecting section 22 connected to the intermediate section 21, the fitting surface 23 is provided at the end of the connecting section 22, and the intermediate section 21 is fixedly connected to the tail section 10. The sleeve assembly 20 is composed of a plurality of intermediate sections 21 and connecting sections 22, so as to further disperse the weight of the device, and the connecting section 22, as the connecting ring part of the tunnel portal 30, can be first connected and fixed to the tunnel portal 30. The intermediate section 21 is then assembled to improve the convenience of construction and the flexibility of adjustment.

[0036] Optionally, the intermediate section 21 and the connecting section 22 are both configured as an integral annular section structure to form a multi-section assembly. Optionally, the intermediate section 21 and the connecting section 22 can be configured as an annular section structure formed by closing two or more petals of shells. A sealing mechanism 213 is provided at the joint of two adjacent shells. Multiple shells are assembled to form the sleeve assembly 20, which can be assembled one by one during the assembly process to improve the convenience of assembly, especially some heavy sleeve assemblies 20, which can adopt a multi-petal assembly structure.

[0037] Preferably, the receiving sleeve device is composed of multiple petals, and optionally, the middle section 21 and the connecting section 22 are fixed by a combination of a multi-petal shell structure. Optionally, the sleeve assembly 20 and the tail section 10 are fixed by a combination of a multi-petal shell structure.

[0038] Preferably, the sleeve assembly 20 includes an upper half shell 211 and a lower half shell 212 that fit together to form a cavity structure. The upper half shell 211 and the lower half shell 212 are installed separately, thereby reducing the weight of a single accessory and performing prefabricated production and processing and on-site assembly construction.

[0039] Preferably, the joint between two adjacent shells is provided with a sealing mechanism 213, and the sealing mechanism 213 seals the joint between the shells. Optionally, the sealing mechanism 213 includes a sealing gasket, and the sealing gasket is limited to the joint between the shells.

[0040] Optionally, one of the two adjacent mating shells is provided with a sealing groove, and the sealing gasket is installed in the sealing groove. Optionally, the sealing mechanism 213 includes a sealing ring, and the sealing ring is squeezed and sealed with the other shell to form an annular sealing structure. Optionally, the sealing mechanism 213 includes a plurality of complementary sealing ribs. The mating end faces of the two adjacent shells are provided with a plurality of arc-shaped plug-in sealing ribs, and a labyrinth-like sealing gap is formed between the adjacent sealing ribs. Preferably, the sealing ribs can be used in conjunction with the sealing ring or the sealing gasket, so as to improve the sealing effect.

[0041] Furthermore, the receiving sleeve device is provided with a plurality of grouting components distributed at intervals, and the grouting components communicate with the receiving cavity. The receiving sleeve device is filled with a filler, and a grouting device connected to the grouting components injects a fluid medium into the receiving sleeve device, so that the pressure maintaining pressure in the receiving sleeve device is controllable. After the tunneling main machine breaks through the tunnel portal 30, it can maintain the tunneling pressure and enter the receiving sleeve device to avoid pressure loss. The construction equipment receives pressure, ensuring the safety of construction and preventing potential hazards such as construction settlement caused by pressure loss.

[0042] The end section member 10 closes the end of the sleeve assembly 20 to form a closed chamber, and the whole device has a cylindrical structure. The sleeve assembly 20 is provided with a plurality of grouting components 24 distributed at intervals, and the grouting components 24 are connected to the grouting equipment to perform grouting operations according to grouting requirements. The grouting components 24 perform grouting operations into the device, improving the construction safety and the flexibility of receiving the tunneling main machine.

[0043] A plurality of grouting components 24 are provided, and the plurality of grouting components 24 are distributed at intervals along the outer peripheral wall of the sleeve assembly 20, so that the slurry can be injected from different positions. Optionally, the number of grouting components 24 is set to one, two, three, five, ten, fifteen, twenty, etc. Preferably, the plurality of grouting components 24 are distributed at intervals along the axial direction of the sleeve assembly 20.

[0044] As Figures 3 to 6 shown, in an embodiment, the outer peripheral wall of the sleeve assembly 20 is provided with a plurality of reinforcing ribs 27, and the reinforcing ribs 27 are distributed on the outer peripheral wall of the sleeve assembly 20, which can improve the structural strength of the sleeve assembly 20. Preferably, some of the reinforcing ribs 27 are distributed at the joint, and are assembled and strengthened as the connecting part. Preferably, the reinforcing ribs 27 are distributed along the connection between the upper half shell 211 and the lower half shell 212 and are locked by fasteners to enhance the connection strength.

[0045] In an embodiment, the cross-section of the sleeve assembly 20 in the direction perpendicular to the center line is circular, rectangular, quasi-rectangular or other cross-sectional shapes adapted to accommodate the tunneling main machine. The sleeve assembly 20 can be adapted to the shape of the tunneling main machine, and the sleeve assembly 20 and the end section member 10 form a cylindrical structure, a rectangular cylindrical structure or a polygonal cylindrical structure. The size of the sleeve assembly 20 is larger than the size of the tunneling main machine to accommodate and receive the tunneling main machine.

[0046] In one embodiment, the sleeve assembly 20 is provided with at least one personnel access opening 25 and a cover assembly 26 connected to the corresponding personnel access opening 25. A seal is provided on the joint surface between the cover assembly 26 and the personnel access opening 25. The personnel access openings 25 are distributed on the outer peripheral wall of the sleeve assembly 20. Materials can be fed into or taken out of the sleeve assembly 20 through the personnel access openings 25. Alternatively, personnel can enter the sleeve assembly 20 through the personnel access openings 25 for welding operations. The cover assembly 26 opens and closes the personnel access opening 25 movably. When the cover assembly 26 closes the personnel access opening 25, a hollow cavity structure is formed inside the sleeve assembly 20.

[0047] Preferably, the number of personnel access openings 25 can be set to one, and one personnel access opening 25 is opened along the side surface of the sleeve assembly 20. Preferably, the number of personnel access openings 25 is set to multiple, and multiple personnel access openings 25 are spaced apart along the outer peripheral wall of the sleeve assembly 20, so as to be able to flexibly layout the flow channels for entering and exiting the sleeve assembly 20 through the personnel access openings 25.

[0048] Preferably, the tail section member 10 is provided with at least one personnel access opening 25 and a cover assembly 26 connected to the corresponding personnel access opening 25. A seal is provided on the joint surface between the cover assembly 26 and the personnel access opening 25.

[0049] The sleeve assembly 20 is fixedly connected to the tunnel portal 30 through the fitting surface 23, and the joint parts are fitted. Specifically, the sleeve assembly 20 is connected to the tunnel portal 30 through the connecting joint 22.

[0050] In an alternative embodiment, the receiving sleeve device and the tunnel portal are mechanically connected. Among them, the sleeve assembly 20 and the tunnel portal 30 are locked and connected by fasteners. The connecting joint 22 and the tunnel portal 30 are fixedly connected by fasteners, which is convenient for disassembly and assembly. For example, the connecting joint 22 is provided with flange flanges at the edges of the fitting surface 23, and a plurality of threaded holes are spaced apart on the tunnel portal 30. The fasteners pass through the holes on the flange flanges and are locked to the threaded holes to form a screw lock.

[0051] In another alternative embodiment, the receiving sleeve device and the tunnel portal are fixedly connected by welding. Among them, the sleeve assembly 20 and the tunnel portal 30 are fixedly connected by welding. The connecting joint 22 is aligned with the tunnel portal 30, and then welding operations are carried out. Optionally, the connecting joint 22 is a segmented or block structure, and the overall weight is reduced to facilitate assembly and splicing. The connecting joint 22 is fixedly welded to the tunnel portal 30, and the joint part has high connection strength and good sealing performance.

[0052] In yet another alternative embodiment, the receiving sleeve device abuts against the tunnel portal under the jacking action of the preloading mechanism. Among them, the sleeve assembly 20 is embedded and fixedly connected to the tunnel portal 30. A fixing ring with an annular structure is fixedly installed in the area of the tunnel portal 30, and the sleeve assembly 20 is embedded and installed in the fixing ring. Alternatively, the tunnel segments in the area of the tunnel portal 30 are correspondingly recessed, and the sleeve assembly 20 is embedded in the tunnel segments and fixedly connected to the tunnel segments, thereby realizing connection and locking. The preloading mechanism is configured to apply pressure to push against the receiving sleeve device so as to connect the receiving sleeve device and the tunnel portal 30. Optionally, the preloading mechanism can be configured as a hydraulic cylinder mechanism, a screw mechanism connecting the tunnel portal and the receiving sleeve device, an electric cylinder mechanism, a cylinder mechanism, a rack and pinion mechanism, etc. The sleeve assembly 20 is embedded and connected to the tunnel portal 30, which is not only accurately positioned but also convenient for fixing.

[0053] The fitting surface 23 is matched and fitted with the tunnel portal 30. For example, when the tunnel portal 30 is arranged on the tunnel segment, the fitting surface 23 is set as a convex arc surface or a concave arc surface or multiple flat surfaces or multiple curves, and the surface form is complementary to the tunnel segment; or, the radius of the arc surface is greater than the radius of the tunnel segment to facilitate the fitting surface 23 to abut against the tunnel segment and have a welding gap. Optionally, when the tunnel portal 30 is arranged at the starting position of the tunnel boring, the tunnel portal 30 has a planar structure. The sleeve assembly 20 is installed on the tunnel portal 30, and the fitting surface 23 is planar to form a planar fitting connection.

[0054] Those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the disclosure herein. This application is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include known common knowledge or conventional technical means in the technical field not disclosed in the present invention. The specification and embodiments are only regarded as exemplary, and the true scope and spirit of the present invention are pointed out by the following claims.

[0055] It should be understood that the present invention is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A receiving sleeve device for a tunnel construction equipment, the receiving sleeve device being used to receive a tunneling main machine, characterized in that, The receiving sleeve device is in the shape of a container, and is formed with a receiving cavity and a fitting surface located at the opening of the receiving cavity, the fitting surface is adapted to the connecting surface of the tunnel portal, and the receiving sleeve device is connected to the tunnel portal.

2. The receiving sleeve device for tunnel construction equipment according to claim 1, characterized in that, The receiving sleeve device includes a tubular sleeve assembly and a tail section that closes one end of the sleeve assembly, and the sleeve assembly and the tail section are an integral structure; or, the sleeve assembly and the tail section are detachably connected, and the fitting surface is arranged at the other end of the sleeve assembly.

3. The receiving sleeve device for tunnel construction equipment according to claim 2, characterized in that, The sleeve assembly includes at least one middle section and a connecting section connected to the middle section. The fitting surface is arranged at the end of the connecting section. The middle section and the tail section are fixedly connected.

4. The receiving sleeve device for tunnel construction equipment according to claim 2, characterized in that, The cross section of the sleeve assembly in a direction perpendicular to the center line is circular, rectangular, quasi-rectangular or other cross-sectional shapes suitable for accommodating the excavation host.

5. The receiving sleeve device for a tunnel construction device according to claim 2, characterized in that, The sleeve assembly and / or the tail section is provided with at least one manhole and a cover assembly connected to the corresponding manhole, and a sealing member is provided on the joint surface between the cover assembly and the manhole.

6. The receiving sleeve device for tunnel construction equipment according to claim 1, characterized in that, The receiving sleeve device is provided with a plurality of grouting assemblies distributed at intervals, and the grouting assemblies are communicated with the receiving cavity.

7. The receiving sleeve device for tunnel construction equipment according to any one of claims 1 to 6, characterized in that, The receiving sleeve device includes two or more shells that are folded together to form the receiving cavity.

8. The receiving sleeve device for tunnel construction equipment according to claim 7, characterized in that, A sealing mechanism is provided at the joint of two adjacent shells.

9. The receiving sleeve device for tunnel construction equipment according to claim 8, characterized in that, The sealing mechanism includes a sealing gasket or a sealing ring or a plurality of complementary sealing ribs.

10. The receiving sleeve device for tunnel construction equipment according to claim 1, characterized in that, The outer peripheral wall of the receiving sleeve device is provided with a plurality of reinforcing ribs.

11. The receiving sleeve device for tunnel construction equipment according to claim 1, characterized in that, The receiving sleeve device and the tunnel portal are mechanically connected; or, the receiving sleeve device and the tunnel portal are fixedly connected by welding; or, the receiving sleeve device is pressed against the tunnel portal under the lifting action of the pre-pressing mechanism.

12. The receiving sleeve device for tunnel construction equipment according to claim 1, characterized in that, The fitting surface is set to be one of a convex arc surface, a concave arc surface, a plane, a multi-segment plane, and a multi-segment curve.

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