Viscous sealing elastic waterproof ring for shield segment joint of hydraulic tunnel and construction method thereof

Abstract

The present application relates to a kind of shield segment joint of hydraulic tunnel and construction method of viscous sealing elastic waterproof ring, the elastic waterproof ring is hollow annular pipe structure, be arranged in the oval extrusion sealing platform reserved in the end surface of shield segment circumferential joint, including steel elastic compressible waterproof pipe and its outside water-swelling rubber tube;The radial section of elastic waterproof ring is circular ring, and it is oval ring after being extruded longitudinally in oval extrusion sealing platform, and blocks circumferential joint.The present application is with the elastic recovery force characteristics of steel elastic compressible waterproof pipe, make elastic waterproof ring continuously press from inside to outside, completely fill the gap of shield segment circumferential joint, improve the water-stopping effect of shield segment circumferential joint, water-swelling rubber tube can still guarantee sealing performance after long time use and aging.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water tunnel construction, in particular to a viscous sealing elastic waterproof ring for shield tunnel segment joints and a construction method. BACKGROUND

[0002] A water tunnel is a structure excavated in a mountain or underground, mainly used for irrigation, power generation, water supply, water discharge, water transportation, construction diversion and navigation, etc., and has the advantages of short mileage, less environmental damage and low degree of interference, and has been widely used in water conservancy construction. In recent years, the focus of water tunnel construction has gradually shifted to areas with complex geological conditions, showing characteristics such as complex structure, variable environment, high water pressure and frequent disasters.

[0003] Shield tunneling has the advantages of high degree of mechanization, rapid and safe excavation, and less construction disturbance, and has unique advantages compared to other tunnel construction methods, and is widely used in tunnel construction. However, different engineering geological conditions have different requirements for shield construction, and complex geotechnical media, water-rich strata, and pressure water head and other external disturbances can cause many tunnel diseases, of which the most common is the leakage problem at the shield segment joint, which is difficult to cure. With the increase of service life, tunnel leakage can cause a series of diseases such as crack development, accelerated erosion, uneven settlement, fatigue damage, etc., which seriously affect the durability and normal use of the tunnel. Shield segment joints weaken the longitudinal and transverse stiffness and strength of the overall structure and local segment structure of the tunnel, and are the weak link of the tunnel waterproof seal. Structural damage, deformation and water leakage are all concentrated on the shield segment joint.

[0004] Currently, the main waterproof method for shield segment joints is to use elastic sealing pads made of porous ethylene propylene diene monomer (EPDM) material. During the shield segment splicing process, the elastic sealing pad is compressed to deform, filling the uneven gaps in the joint. At the same time, due to external forces, the elastic sealing pad will generate a large elastic reaction force, which can keep the gap persistent and dense, ultimately achieving the effect of sealing the joint leakage. However, in actual use, it is found that such sealing pads will age and other problems after long-term use, and the compression elasticity cannot meet the requirements, resulting in a decrease in the waterproof performance of the joint with the decrease in compression reaction force, ultimately leading to the failure of the joint waterproof system. At the same time, the shield segment may also have joint opening and misalignment during assembly and use. This phenomenon will cause the connected sealing pad to be subjected to longitudinal compression force and transverse friction force at the same time, making the sealing pad prone to tensile deformation or even falling off.

[0005] Therefore, it is necessary to propose new devices and measures to overcome the above-mentioned defects. SUMMARY

[0006] The present application aims to provide a viscous sealing elastic waterproof ring for shield segment joints of hydraulic tunnels and a construction method, so as to solve the problems of aging of sealing pads after long-term use, inability to meet the requirements of elasticity, and easy stretching deformation and even falling off.

[0007] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] The viscous sealing elastic waterproof ring for shield segment joints of hydraulic tunnels is a hollow annular pipe structure, which is arranged in an oval extrusion sealing platform reserved at the end face of the circumferential joint of the shield segment, and comprises a steel elastic compressible waterproof pipe and a water-swelling rubber pipe outside the steel elastic compressible waterproof pipe.

[0009] The radial section of the elastic waterproof ring is in the shape of a circular ring, and is in the shape of an elliptical ring after being longitudinally extruded in the oval extrusion sealing platform, and blocks the circumferential joint.

[0010] Further, the oval extrusion sealing platform is an arc groove arranged at the end face of the circumferential joint of the shield segment.

[0011] After a plurality of shield segments are circumferentially spliced, a plurality of arc grooves are circumferentially connected to form a circumferential groove.

[0012] After two shield segments are longitudinally spliced, two circumferential grooves are butt-jointed to form a circumferential cavity, and the radial section of the circumferential cavity is in the shape of an ellipse; the circumferential length of the radial section of the circumferential cavity is the same as the outer circumferential length of the radial section of the elastic waterproof ring in the shape of a circular ring.

[0013] Further, the outer wall of the water-swelling rubber pipe is provided with a pressure-sensitive reaction type strong self-adhesive.

[0014] Further, the surface of the pressure-sensitive reaction type strong self-adhesive is provided with silicone oil paper.

[0015] Further, the outer wall of the water-swelling rubber pipe is uniformly provided with concave locking holes.

[0016] Further, the water-swelling rubber pipe is made of a porous water-swelling rubber material made of ethylene-propylene-diene rubber and hydrophilic superabsorbent material.

[0017] On the other hand, a construction method of the viscous sealing elastic waterproof ring for shield segment joints of hydraulic tunnels is provided, and the method comprises:

[0018] The elastic waterproof ring is prefabricated.

[0019] After the first ring of the shield segment is spliced into a ring, one side of the elastic waterproof ring is bonded into the annular groove of the end face of the annular joint of the first ring, and the other side of the elastic waterproof ring is exposed;

[0020] The second ring of the shield segment is continuously spliced, and after being spliced into a ring, the second ring of the shield segment is butted with the first ring of the shield segment, and the other side of the elastic waterproof ring is bonded into the annular groove of the end face of the annular joint of the second ring of the shield segment;

[0021] The annular grooves on the longitudinal two sides are close to each other and constitute the annular cavity, the elastic waterproof ring is extruded to deform longitudinally, and the radial section of the elastic waterproof ring changes from a circular ring to an elliptical ring.

[0022] Further, the elastic waterproof ring is prefabricated, comprising:

[0023] The water-swelling rubber pipe is made of porous water-swelling rubber material;

[0024] The steel elastic compressible waterproof pipe is made of thin-walled steel pipe;

[0025] The water-swelling rubber pipe is sleeved on the steel elastic compressible waterproof pipe, and then is bent to form a hollow annular pipe.

[0026] Further, the elastic waterproof ring is prefabricated, comprising:

[0027] Locking holes are prefabricated on the outer wall of the water-swelling rubber pipe;

[0028] After the hollow annular pipe is formed, the pressure-sensitive reaction type strong self-adhesive is coated on the outer wall of the water-swelling rubber pipe, and the locking holes are filled.

[0029] Further, the elastic waterproof ring is prefabricated, comprising:

[0030] The surface of the pressure-sensitive reaction type strong self-adhesive is covered with the silicone oil paper, and the silicone oil paper is uncovered during construction.

[0031] Compared with the prior art, the beneficial effects of the present application are as follows:

[0032] The application provides a water conservancy tunnel shield segment joint viscosity sealing elastic waterproof ring and a construction method. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings of other embodiments can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0034] Figure 1 is a transverse sectional structure diagram of the elastic waterproof ring provided by the present application.

[0035] Figure 2 is a radial sectional structure diagram of the elastic waterproof ring provided by the present application.

[0036] Figure 3 is a radial sectional structure diagram of the elastic waterproof ring provided by the present application before being compressed in the elliptical extrusion sealing platform.

[0037] Figure 4 is a radial sectional structure diagram of the elastic waterproof ring provided by the present application after being compressed in the elliptical extrusion sealing platform.

[0038] Figure 5 is a micro-porous structure diagram of the water-swelling rubber tube.

[0039] In the figure, the following are marked:

[0040] 1-elliptical extrusion sealing platform, 2-shield segment, 3-water-swelling rubber tube, 4-steel elastic compressible waterproof tube, 5-pressure-sensitive reaction type strong self-adhesive, 6-elastic waterproof ring, 7-silicone oil paper, 8-locking glue hole. DETAILED DESCRIPTION

[0041] For the purpose of promoting the understanding of the present application, the present application will be described in further detail below with reference to the attached drawings. In the drawings, preferred embodiments of the present application are shown. However, the present application can be realized in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the present application to those skilled in the art.

[0042] In the description of the present application, it needs to be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be understood as a limitation of the present application.

[0043] In the description of the present application, it needs to be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "setting" and the like should be understood broadly, for example, it can be fixedly connected, set, or detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] It should also be noted that although the sequence of steps is involved in the method description, in some cases, it can be performed in a different order from here, and should not be understood as a limitation on the sequence of steps.

[0045] In the specific embodiment, the length direction of the water tunnel is defined as the longitudinal direction, the direction perpendicular thereto is defined as the transverse direction, the lining profile of the water tunnel segment is defined as the circumferential direction, and the direction radiating outward from the center of the water tunnel is defined as the radial direction.

[0046] The present application provides a viscous sealing elastic waterproof ring for the shield segment joint of a water tunnel, which is suitable for long, large and deep buried water tunnel shield segment assembly construction and plays an important sealing and waterproof role in the circumferential joint of the shield segment.

[0047] Specifically, as Figure 1 and Figure 2 , the elastic waterproof ring 6 is a hollow annular pipe structure, the transverse cross section is a circular ring, and the radial cross section is also a circular ring, which is a hollow circular ring body with elasticity and deformation. The elastic waterproof ring 6 includes a steel elastic compressible waterproof pipe 4 and a water-swelling rubber pipe 3 outside it, the outer wall of the water-swelling rubber pipe 3 is provided with a pressure-sensitive reaction type strong self-adhesive 5, and the surface of the pressure-sensitive reaction type strong self-adhesive 5 is provided with a silicon oil paper 7.

[0048] Among them:

[0049] The steel elastic compressible waterproof pipe 4 is made of thin-walled steel pipe. Due to the small thickness of the pipe wall, the pipe can be bent to form a circular ring. At the same time, the thin-walled steel pipe can be radially extruded and deformed, and the cross section changes from a circular shape to an oval shape. The steel elastic compressible waterproof pipe 4 has a sustained outward resistance after being extruded, which gives the elastic waterproof ring 6 elasticity. The steel elastic compressible waterproof pipe 4 can be made of 304 austenitic stainless steel. Due to its high elastic modulus and yield strength, the thin-walled stainless steel pipe has excellent elasticity and mechanical properties, and can well restore its original shape after being compressed. Under normal conditions, it shows the characteristics of nearly complete rebound. In addition, in order to enhance the elastic recovery force characteristics of the steel pipe, the small thickness of the circumferential gap of the shield segment is used to set the steel pipe in the form of small pipe diameter and thin wall thickness to increase its elastic recovery force. At the same time, the steel pipe has a larger elastic recovery force in the radial direction, which is the direction used by the present application. Through multiple factors, the elastic recovery force of the steel elastic compressible waterproof pipe is ensured.

[0050] The water-swelling rubber pipe 3 can swell rapidly after absorbing water, increase in volume, generate greater friction and sealing effect, and give the elastic waterproof ring 6 sealing properties. Specifically, the water-swelling rubber material used in the water-swelling rubber pipe 3 is a porous material made by blending ethylene-propylene-diene rubber with hydrophilic superabsorbent material (such as cross-linked polyacrylic acid sodium, etc.).

[0051] The pressure-sensitive reactive strong self-adhesive 5 uses an acrylate pressure-sensitive adhesive to give the elastic waterproof ring 6 tackiness. "Pressure-sensitive" means that it can be immediately adhered to the surface of an object under the application of slight pressure without the need for additional heating, solvents or catalysts and other treatment characteristics. The "pressure-sensitive" characteristic can quickly bond the elastic waterproof ring 6 in the groove to achieve waterproofing effect, provide waterproof efficiency, and shorten the construction time.

[0052] The silicone oil paper 7 covers the pressure-sensitive reactive strong self-adhesive 5 to provide protection against premature swelling of the water-swelling rubber in a humid tunnel construction environment. At the same time, it is convenient for transportation and handling. After the silicone oil paper 7 is removed and the pressure-sensitive reactive strong self-adhesive 5 is exposed, the elastic waterproof ring 6 can be directly fixed and installed by adhesive bonding.

[0053] To install the elastic waterproof ring 6, the circumferential joint end surface of the shield segment 2 is provided with an oval extrusion sealing platform 1. The oval extrusion sealing platform 1 is an arc groove provided on the circumferential joint end surface of the shield segment 2. After a plurality of shield segments 2 are circumferentially spliced, a plurality of arc grooves are circumferentially connected to form a circumferential groove. After two rings of shield segments 2 are longitudinally spliced, the two circumferential grooves are connected to form a circumferential cavity, and the radial cross section of the circumferential cavity is oval. The elastic waterproof ring 6 is located in the oval extrusion sealing platform 1 reserved on the circumferential joint end surface of the shield segment 2, as shown in Figure 3, the radial section of the elastic waterproof ring 6 is circular, and the radial height of the elastic waterproof ring 6 is less than the thickness of the shield segment 2 and is arranged in the center in the oval extrusion sealing platform 1. Figure 4 , the radial section of the elastic waterproof ring 6 is changed into an elliptical ring, and the radial section of the elastic waterproof ring 6 fills the entire annular cavity and blocks the annular gap.

[0054] In some embodiments, the outer wall of the water-swelling rubber tube 3 is also uniformly provided with concave locking holes 8, and after the pressure-sensitive reaction type strong self-adhesive 5 is coated, the pressure-sensitive reaction type strong self-adhesive 5 can fill the locking holes 8 and increase the adhesion.

[0055] The elastic waterproof ring 6 has the following technical advantages:

[0056] 1. The structure of the present application is designed for the characteristics of the jacking extrusion installation of the shield segment annular gap, and can form a dense gap at the shield segment joint by the characteristics of the annular gap jacking pressure, thereby achieving a very good waterproof effect.

[0057] 2. The elastic recovery force characteristics of the steel elastic compressible waterproof tube 4 can ensure that the elastic waterproof ring 6 continuously presses outward from the inside, ensures that it completely fills the segment gap, and improves the waterproof effect of the segment joint.

[0058] 3. The self-expanding characteristics of the water-swelling rubber tube 3 ensure that the elastic waterproof ring 6 can completely fill the irregular local gap of the segment in the working state, increase the density of the gap, and improve the waterproof performance of the joint.

[0059] 4. The pressure-sensitive reaction type strong self-adhesive 5 arranged on the outside of the water-swelling rubber tube 3 ensures that the steel elastic compressible waterproof tube 4 and the elastic waterproof ring 6 are tightly attached after compression, thereby improving the toughness of the segment structure while ensuring the sealing performance of the joint.

[0060] 5. The silicone oil paper 7 arranged on the surface of the water-swelling rubber tube 3 ensures that the water-swelling rubber tube 3 will not fail due to the humid environment of the tunnel or early contact with other objects before installation and use.

[0061] During the shield tunnel segment construction of a hydraulic tunnel, the shield tunnel segments 2 are assembled in a ring from bottom to top and from outside to inside of the tunnel. When the ring of segments is stable on the wall, the support legs of the shield machine are pressed against the innermost ring of segments, the rock is broken by the rotating cutter head at the front end of the shield machine, and the new tunnel working face is formed by pushing the rock into the tunnel. Then the support legs of the shield machine are lowered, and the assembly of the next ring of segments is started again.

[0062] Based on the shield construction, the construction method of the adhesive sealing elastic waterproof ring of the joint of the hydraulic tunnel shield segment of the present application specifically comprises the following steps:

[0063] S1: prefabricating the elastic waterproof ring 6. Specifically, it comprises:

[0064] S101: using a porous water-swelling rubber material to make a water-swelling rubber pipe 3, and prefabricating locking glue holes 8 on the outer wall of the water-swelling rubber pipe 3.

[0065] S102: using a thin-walled steel pipe to make a steel elastic compressible waterproof pipe 4.

[0066] S103: sleeving the water-swelling rubber pipe 3 outside the steel elastic compressible waterproof pipe 4, and then bending to form a hollow annular pipe.

[0067] Specifically, the water-swelling rubber pipe 3 can be first made as a long strip, and the short edge length is slightly smaller than the outer circumference of the steel elastic compressible waterproof pipe 4. During assembly, the steel elastic compressible waterproof pipe 4 is bonded from the side close to the center, and a slight pulling force is applied to make it tightly fit outside the steel elastic compressible waterproof pipe 4.

[0068] S104: coating a pressure-sensitive reaction type strong self-adhesive 5 on the outer wall of the water-swelling rubber pipe 3, and filling the locking glue holes 8.

[0069] S105: covering the surface of the pressure-sensitive reaction type strong self-adhesive 5 with a silicone oil paper 7. During construction, the silicone oil paper 7 can be removed.

[0070] S2: after the first ring of shield tunnel segments 2 is ring-connected, the surface silicone oil paper 7 of any half of the elastic waterproof ring 6 is removed, one side of the elastic waterproof ring 6 is bonded to the center position of the ring groove on the end surface of the first ring of shield tunnel segments 2, and the silicone oil paper on the other side of the elastic waterproof ring 6 is not removed to ensure that the water-swelling rubber does not fail prematurely due to the humid construction environment of the tunnel.

[0071] S3: after the bonding of the elastic waterproof ring 6 is completed, the second ring of shield tunnel segments 2 is continued to be assembled, and after the ring connection, the second ring of shield tunnel segments 2 is butt-jointed with the first ring of shield tunnel segments 2. The silicone oil paper 7 on the other side of the elastic waterproof ring 6 that has not been removed is removed, and the other side of the elastic waterproof ring 6 is bonded to the ring groove on the end surface of the second ring of shield tunnel segments 2.

[0072] S4: the force of the back side of the pipe piece is pushed forward by the action of the shield machine, the annular grooves on the longitudinal sides are close to each other, completely contact and close, form an annular cavity, and extrude the elastic waterproof ring 6 to make it longitudinally deformed, and the radial section of the elastic waterproof ring 6 changes from a circular ring to an elliptical ring.

[0073] At the same time, in the extrusion process, the water-swelling rubber tube 3 will be extruded under the combined action of the back side of the pipe piece pushing force and the restoring force of the steel elastic compressible waterproof pipe 4, in this process, the water-swelling rubber tube 3 will completely fill the irregular local gap between the pipe pieces, and under the influence of the humid environment in the tunnel and the seepage water behind the pipe pieces, the water-swelling rubber tube 3 will automatically expand, increasing the filling effect of the gap.

[0074] Finally, the elastic waterproof ring 6 and the elliptical extrusion sealing platform 1 are firmly bonded together by the pressure-sensitive reaction type strong self-adhesive 5, completely sealing the pipe piece ring gap joint, forming a sealed ring-mounted waterproof structure.

[0075] During construction, the interface of the elastic waterproof ring 6 is staggered with the longitudinal joint of the shield pipe piece 2 to avoid joint communication.

[0076] Due to the special structure design of the present application, the present application can be directly installed and fixed by bonding method during construction, which is convenient for construction and has high efficiency, and has positive promotion significance.

[0077] The above application of specific examples to the present application is only used to help understand the present application and does not limit the present application. For those skilled in the art to which the present application belongs, according to the idea of the present application, several simple deductions, deformations or substitutions can be made.

Claims

1. An adhesive sealing elastic waterproof ring for the joints of shield tunnel segments in hydraulic engineering tunnels, characterized in that: The elastic waterproof ring (6) is a hollow annular tube structure, which is set in the elliptical extrusion sealing platform (1) reserved on the end face of the circumferential joint of the shield tunnel segment (2), including a steel elastic compressible waterproof tube (4) and its external water-swellable rubber tube (3). The radial cross-section of the elastic waterproof ring (6) is circular. After being longitudinally compressed in the elliptical compression sealing platform (1), it becomes an elliptical ring and seals the circumferential seam. The elliptical compression sealing platform (1) is an arc-shaped groove set on the circumferential seam end face of the shield tunnel segment (2); After multiple shield tunnel segments (2) are spliced ​​circumferentially, multiple arc-shaped grooves are connected circumferentially to form a circumferential groove; After the shield tunnel segments (2) of the two rings are longitudinally spliced, the two circumferential grooves are joined together to form a circumferential cavity. The radial cross-section of the circumferential cavity is elliptical. The circumference of the elliptical radial cross-section of the circumferential cavity is the same as the circumference of the outer circle of the radial cross-section of the elastic waterproof ring (6). The outer wall of the water-swellable rubber tube (3) is provided with pressure-sensitive reactive strong self-adhesive (5).

2. The adhesive sealing elastic waterproof ring for the joint of shield tunnel segments in hydraulic tunnels according to claim 1, characterized in that: The surface of the pressure-sensitive reactive strong self-adhesive (5) is provided with silicone paper (7).

3. The adhesive sealing elastic waterproof ring for the joint of shield tunnel segments in hydraulic tunnels according to claim 2, characterized in that: The outer wall of the water-swellable rubber tube (3) is uniformly provided with recessed locking holes (8).

4. The adhesive sealing elastic waterproof ring for the joint of shield tunnel segments in hydraulic tunnels according to claim 3, characterized in that: The water-swellable rubber tube (3) is made of porous water-swellable rubber material made by blending EPDM rubber with hydrophilic super absorbent material.

5. The construction method of the adhesive sealing elastic waterproof ring for the joint of the shield tunnel segment as described in claim 4, characterized in that: The method includes: Prefabricate the elastic waterproof ring (6); After the shield tunnel segments (2) of the first ring are spliced ​​into a ring in the circumferential direction, one side of the elastic waterproof ring (6) is bonded to the circumferential groove at the end face of the circumferential joint of the shield tunnel segment (2) of the first ring, and the other side of the elastic waterproof ring (6) is exposed. Continue splicing the shield tunnel segments (2) of the second ring. After splicing them into a ring, connect the shield tunnel segments (2) of the second ring with the shield tunnel segments (2) of the first ring. The other side of the elastic waterproof ring (6) is bonded to the circumferential groove on the circumferential joint end face of the shield tunnel segments (2) of the second ring. The circumferential grooves on both sides of the longitudinal direction approach each other to form the circumferential cavity, which compresses the elastic waterproof ring (6) to cause longitudinal deformation, and the radial cross section of the elastic waterproof ring (6) changes from a circular ring to an elliptical ring.

6. The construction method of the adhesive sealing elastic waterproof ring for the joint of the shield tunnel segment in hydraulic tunnel according to claim 5, characterized in that: The prefabricated elastic waterproof ring (6) includes: The water-swellable rubber tube (3) is made using a porous water-swellable rubber material. The steel elastic compressible waterproof pipe is made using a thin-walled steel pipe (4); The water-swellable rubber tube (3) is fitted over the steel elastic compressible waterproof tube (4) and then bent to form a hollow annular tube.

7. The construction method for the adhesive sealing elastic waterproof ring of the tunnel segment joint in hydraulic tunnels according to claim 6, characterized in that: The prefabricated elastic waterproof ring (6) also includes: Locking holes (8) are pre-made on the outer wall of the water-swellable rubber tube (3); After the hollow annular tube is formed, the pressure-sensitive reactive strong self-adhesive (5) is coated on the outer wall of the water-swellable rubber tube (3), and the locking hole (8) is filled.

8. The construction method for the adhesive sealing elastic waterproof ring of the tunnel segment joint in hydraulic tunnels according to claim 7, characterized in that: The prefabricated elastic waterproof ring (6) also includes: Cover the surface of the pressure-sensitive reactive strong self-adhesive (5) with the silicone paper (7), and peel off the silicone paper (7) during construction.

Images