CN112281887A - Open caisson in hard plastic cohesive soil area and construction method thereof - Google Patents
Open caisson in hard plastic cohesive soil area and construction method thereof Download PDFInfo
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- CN112281887A CN112281887A CN202011016335.4A CN202011016335A CN112281887A CN 112281887 A CN112281887 A CN 112281887A CN 202011016335 A CN202011016335 A CN 202011016335A CN 112281887 A CN112281887 A CN 112281887A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D23/00—Caissons; Construction or placing of caissons
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D23/00—Caissons; Construction or placing of caissons
- E02D23/08—Lowering or sinking caissons
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D23/00—Caissons; Construction or placing of caissons
- E02D23/08—Lowering or sinking caissons
- E02D23/14—Decreasing the skin friction while lowering
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D23/00—Caissons; Construction or placing of caissons
- E02D23/16—Jointing caissons to the foundation soil, specially to uneven foundation soil
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Abstract
The invention relates to the technical field of bridge construction, in particular to a sunk well in a hard plastic cohesive soil area and a construction method thereof. The well wall, the partition wall, the first cutting edge and the second cutting edge are included; the partition wall is arranged in the well wall and used for uniformly dividing the open caisson into a plurality of partition bins; the first cutting edge is arranged at the bottom of the well wall, a first steel plate covers the surface of the first cutting edge, and the shape of the first steel plate is the same as that of the first cutting edge; the second cutting edge is arranged at the bottom of the partition wall, a second steel plate is covered on the surface of the second cutting edge, and the shape of the second steel plate is the same as that of the second cutting edge. According to the invention, the open caisson is poured in situ, the open caisson is divided into a plurality of uniform compartments by partition walls, and steel plates are covered on the well wall and the blade feet below the partition walls; the limit that the hard plastic cohesive soil area is not suitable for constructing the open caisson foundation is broken through, the technical problem of open caisson construction in the hard plastic cohesive soil area is solved, and the safety, the economy and the rationality of large open caisson construction are ensured.
Description
Technical Field
The invention relates to the technical field of bridge construction, in particular to a sunk well in a hard plastic cohesive soil area and a construction method thereof.
Background
The open caisson foundation has high structural rigidity and strong bearing capacity, and is suitable for being used as a cable tower foundation and an anchorage foundation of a large-span cable-stayed bridge and a suspension bridge. The friction between the well wall and the soil layer and the reaction force of the blade foot are overcome by taking soil in the well, so that the open caisson sinks into the designed elevation position below the ground, and the foundation of the open caisson has the difficulty of sinking construction. The open caisson foundation of the large-span bridge is applied to the middle and lower reaches of Yangtze river of China mostly, the stratum mainly comprises mucky soil and sandy soil, the water content of the soil layer is high, and part of open caisson is built in water. In the northern hard plastic cohesive soil area of China, the friction resistance of the hard plastic cohesive soil layer is large, the underground water level is a certain depth below the ground, the open caisson construction faces the sinking difficulty, and the construction technology of the middle and lower reaches of Yangtze river is not suitable for the northern hard plastic cohesive soil area.
Disclosure of Invention
The invention aims to provide a sunk well in a hard plastic cohesive soil area and a construction method thereof, so as to improve the problems. In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
on one hand, the application provides a hard plastic sticky land area open caisson which comprises a well wall, a partition wall, a first blade foot and a second blade foot; the partition wall is arranged in the well wall and used for uniformly dividing the open caisson into a plurality of compartments, and a chamfer is arranged at the corner of each compartment; the first cutting edge is arranged at the bottom of the well wall, a first steel plate covers the surface of the first cutting edge, and the shape of the first steel plate is the same as that of the first cutting edge; the second cutting edge is arranged at the bottom of the partition wall, a second steel plate is covered on the surface of the second cutting edge, and the shape of the second steel plate is the same as that of the second cutting edge.
Optionally, the thicknesses of the first steel plate and the second steel plate are 10 mm-20 mm; the distance between the bottom surface of the partition wall and the bottom surface of the second cutting edge is 50 cm.
Optionally, a transverse gas supply pipe is embedded at the outer side of the well wall, a plurality of grooves are formed in the well wall at the outer side of each transverse gas supply pipe, each groove is in a quadrangular frustum pyramid shape, the top surfaces of the grooves are in contact with the transverse gas supply pipe, and the bottom surfaces of the grooves are arranged on the outer surface of the well wall; and the transverse air supply pipe opposite to the top surface of the groove is provided with an air injection hole.
Optionally, the gas injection holes are arranged on the upper side of the transverse gas supply pipe; the bottom surface of the groove is an isosceles trapezoid, and the length of the upper bottom of the isosceles trapezoid formed by the bottom surface is greater than that of the lower bottom; the orthographic projection of the top surface of the groove on the bottom surface is positioned at the lower side of the bottom surface.
Optionally, the transverse air supply pipe comprises a plurality of transverse air supply pipes, each transverse air supply pipe is parallel to the other transverse air supply pipe, and each transverse air supply pipe is in hot-melt connection with the longitudinal air supply pipe; the grooves on the outer sides of two adjacent transverse gas supply pipes are arranged at intervals.
Optionally, the distance between the top surface and the bottom surface of each groove is 3 cm-5 cm, the distance between two adjacent grooves is 1.0 m-1.5 m, and 4-6 air injection holes are provided for each groove.
On the other hand, the invention provides a sunk well construction method in a hard plastic cohesive soil area, which comprises the following steps: removing surface layer floating soil, and tamping the foundation pit without the surface layer floating soil; laying a sand cushion layer in the tamped foundation pit; the sand cushion layer is filled layer by layer, and the medium coarse sand is vibrated and compacted by a vibrating rod; after the sand cushion is filled, carrying out a bearing capacity experiment to ensure that the construction requirements are met; constructing a first blade foot and a second blade foot, and backfilling coarse sand in the side surfaces of each first blade foot and each second blade foot after the construction of the first blade foot and the second blade foot is finished, and vibrating and compacting; then pouring the well wall on the basis of the first blade foot and the second blade foot; during sinking construction, a dry-excavation soil-taking method is firstly adopted for construction; when the open caisson is below the underground water level and has no water seepage or less water seepage, the construction is carried out by adopting a flushing and sucking mud drainage sinking method; when the open caisson is below the underground water level and the water seepage amount is large, the construction is carried out by adopting an air mud suction non-drainage sinking method; in the sinking construction process, a dry-digging soil-taking method is adopted for construction when a hard clay layer or a hard cemented round gravel layer is encountered.
Optionally, the method further comprises: during sinking construction, firstly carrying out soil taking construction in a first area in the open caisson, carrying out soil taking construction in a second area when the maximum depth of the bottom of a pan at the bottom of the first area is H1, and carrying out soil taking construction in a third area when the maximum depth of the bottom of a pan at the bottom of the second area is H2; the value of H1 is greater than that of H2; the first area is one or more compartments in the center of the open caisson; the second area is a plurality of compartments at the left side and the right side of the first area; the third area is a plurality of compartments at the upper side and the lower side of the first area; when soil taking construction is carried out in the third area, the observation is carried out to pay attention to the sinking condition of the open caisson, when the open caisson sinks, the soil taking construction is stopped, and after the open caisson sinks to stop, soil taking construction is continued to be carried out in the third area until the soil body is flush with the second area.
Optionally, the value of H1 is: h1 is more than or equal to 0.5m and less than or equal to 1 m; the value of H2 is more than or equal to 0m and less than or equal to H1 and less than or equal to 0.5 m.
Optionally, in the soil borrowing construction process, the soil borrowing depth difference of the first area, the second area and the third area is controlled within 1 m.
The invention has the beneficial effects that:
according to the invention, the open caisson is poured in situ, the open caisson is divided into a plurality of uniform compartments by partition walls, and steel plates are covered on the well wall and the blade feet below the partition walls; the limit that the hard plastic cohesive soil area is not suitable for constructing the open caisson foundation is broken through, the technical problem of open caisson construction in the hard plastic cohesive soil area is solved, and the safety, the economy and the rationality of large open caisson construction are ensured.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the embodiments of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic structural diagram of a hard plastic sticky land area open caisson with a rectangular cross section according to an embodiment of the invention;
FIG. 2 is a schematic structural sectional view of a large cantilever beam of an open caisson in a hard plastic cohesive soil area, which is provided with a circular section in the embodiment of the invention;
fig. 3 is a schematic view of a first blade edge structure according to an embodiment of the present invention;
fig. 4 is a schematic view of a second blade edge structure according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a groove structure according to an embodiment of the present invention;
FIG. 6 is a schematic side view of a groove structure according to an embodiment of the present invention;
FIG. 7 is a schematic view of a sand mat structure according to an embodiment of the present invention;
FIG. 8 is a schematic view of the soil borrowing construction method according to the embodiment of the invention;
fig. 9 is a backfill schematic diagram for construction of a suspension bridge anchorage open caisson in the embodiment of the invention.
The labels in the figure are: 1. a well wall; 2. a partition wall; 3. a steel plate; 4. a groove; 5. a transverse gas supply tube; 6. a gas injection hole; 7. a sand cushion layer; 8. constructing a pit; 9. a first blade leg; 10. a second blade leg; 11. a second steel plate; 12. a drainage ditch; 13. concrete; 14. and (4) soil.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures. Meanwhile, in the description of the present invention, the terms "first", "second", and the like are used only for distinguishing the description, and are not to be construed as indicating or implying relative importance.
On one hand, the embodiment provides a sunk well in a hard plastic cohesive soil area, which comprises a well wall 1; be provided with a plurality of partition walls 2 in the wall of a well 1, a plurality of partition walls 2 will be with open caisson evenly divided into a plurality of compartments, the corner of every compartment all is provided with the chamfer. The open caisson is of a reinforced concrete structure. As shown in fig. 1 and 2, the open caisson section comprises a rectangular section and a circular section, and is composed of a well wall 1 and a partition wall 2. Rectangular cross section adopts vertical and horizontal subdivision, and circular cross section adopts hoop subdivision, and partition wall 2 arranges and should make the compartment area balanced as far as possible, the interior borrow of being convenient for. The four corners of the rectangular cross section are provided with round chamfers, the friction area of the well wall 1 is reduced, the soil taking difficulty in the well is reduced, the thickness of the well wall 1 is 2.0-2.5 m, the thickness of the partition wall 2 is 1.0-1.5 m, and the peduncle cooperation is arranged between the partition wall 2 and the well wall 1 and between the partition wall 2 and the partition wall 2. The section is circular, the thickness of the well wall 1 is 2.0-2.5 m, the thickness of the partition wall 2 is 1.0-1.5 m, and the peduncles are arranged between the partition wall 2 and the well wall 1 and between the partition wall 2 and the partition wall 2.
As shown in fig. 3, a first cutting edge 9 is arranged at the bottom of the well wall 1, a first steel plate 3 is covered on the surface of the first cutting edge 9, the soil cutting capability is increased when the first steel plate 3 penetrates through hard plastic cohesive soil, and the shape of the first steel plate 3 is the same as that of the first cutting edge 9;
as shown in fig. 4, the bottom of the partition wall 2 is provided with a second blade leg 10, the surface of the second blade leg 10 is covered with a second steel plate 11, the soil cutting capability is increased when the hard plastic cohesive soil passes through, and the shape of the second steel plate 11 is the same as that of the second blade leg 10.
The thickness of the first steel plate 3 and the second steel plate 11 is 10 mm-20 mm; the distance between the bottom surface of the partition wall 2 and the bottom surface of the second cutting foot 10 is 50 cm.
Optionally, as shown in fig. 5 and 6, a transverse gas supply pipe 5 is buried outside the well wall 1, a plurality of grooves 4 are formed in the well wall 1 outside each transverse gas supply pipe 5, each groove 4 is in a quadrangular frustum shape, top surfaces of the grooves 4 are in contact with the transverse gas supply pipe 5, and bottom surfaces of the grooves 4 are arranged on the outer surface of the well wall 1; and the transverse air supply pipe 5 opposite to the top surface of the groove 4 is provided with an air injection hole 6.
The gas injection holes 6 are arranged on the upper side of the transverse gas supply pipe 5; the bottom surface of the groove 4 is an isosceles trapezoid, and the length of the upper bottom of the isosceles trapezoid formed by the bottom surface is greater than that of the lower bottom; the orthographic projection of the top surface of the groove 4 on the bottom surface is located on the lower side of the bottom surface. The length of the upper bottom of the bottom surface of the groove 4 is 18cm, the length of the lower bottom is 15cm, and the distance between the top surface and the bottom surface of the groove 4 is 4 cm.
The number of the transverse air supply pipes 5 is multiple, each transverse air supply pipe 5 is parallel to each other, and each transverse air supply pipe 5 is in hot-melt connection with the longitudinal air supply pipe; the grooves 4 on the outer side of two adjacent transverse gas supply pipes 5 are arranged at intervals.
The distance between the top surface and the bottom surface of each groove 4 is 3-5 cm, the distance between two adjacent grooves 4 is 1.0-1.5 m, and 4-6 air injection holes 6 corresponding to each groove 4 are arranged.
In order to reduce the friction force of the hard plastic cohesive soil, an air curtain structure is adopted. The outer side of the well wall 1 is provided with a groove 4, and an air supply pipeline is pre-buried in the well wall 1. The grooves 4 are arranged in a quincunx shape, when the concrete of the well wall 1 is poured, the square frustum-shaped grooves are formed by a mould, and the air supply pipeline is pre-buried in the positions of the grooves 4. After the well wall is demoulded, 5 gas injection holes 6 with the diameter of 1mm are drilled on the gas supply pipe by a drilling machine. The transverse air supply pipe 5 and the longitudinal air supply pipe are both PP-R pipes, and the pre-buried air pipes are connected through hot melting.
In another aspect, the present embodiment provides a method for constructing a sinking well in a hard plastic cohesive soil area, where the method includes step S10, step S20, step S30, step S40, and step S50.
S10, removing surface layer floating soil, and tamping the foundation pit without the surface layer floating soil;
s20, paving a sand cushion layer in the tamped foundation pit; the sand cushion layer is filled layer by layer, and the medium coarse sand is vibrated and compacted by a vibrating rod; drainage ditches 12 are arranged at the two sides of the sand cushion layer;
step S30, after the sand cushion is filled, carrying out a bearing capacity experiment to ensure that the construction requirements are met;
step S40, constructing the first blade foot 9 and the second blade foot 10, and after the construction of the first blade foot 9 and the second blade foot 10 is completed, backfilling coarse sand in the side surface of each first blade foot 9 and each second blade foot 10 and vibrating the coarse sand to be dense, as shown in figure 7; then pouring the well wall 1 on the basis of the first blade foot 9 and the second blade foot 10; compared with the conventional skid scheme, the method has the advantages that the sand cushion layer is adopted, the bearing capacity is high, the sand cushion layer is excavated during initial sinking, and the sinking is convenient.
Step S50, during sinking construction, firstly, a dry excavation soil taking method is adopted for construction, an excavator is hoisted into a sinking well by utilizing a crawler crane, the excavator is adopted for taking soil, a soil body is hoisted and transported to the outside of the sinking well by adopting a crane matched with a hopper, and the soil body is directly loaded and transported to a permanent spoil area for dumping; when the open caisson is below the underground water level and has no water seepage or less water seepage, constructing by adopting a mud flushing and sucking drainage sinking method, flushing a water collecting pit in a well hole by using a high-pressure water gun, flushing and cutting a soil body by using the high-pressure water gun to form mud, discharging the mud into a mud sedimentation tank outside the open caisson by using a mud pump, and after the mud is separated in the sedimentation tank, transporting the muck to a waste soil field for dumping; when the open caisson is below the underground water level and the water seepage amount is large, constructing by adopting an air mud suction non-drainage sinking method, erecting a mud suction platform on the top of the open caisson, installing a gantry crane, moving the mud suction machine by using the gantry crane to operate, extending the air mud suction machine into the bottom of the open caisson, pressing compressed air into a mud suction machine mixing chamber to ensure that the density of mud-water-gas mixed liquid is lower than that of water, sucking the base silt out of the open caisson under the action of water pressure and discharging the base silt into a mud sedimentation tank outside the open caisson, separating mud in the sedimentation tank, transporting residue soil to a waste soil yard for dumping, and timely replenishing water into the open caisson in the mud suction sinking process; in the sinking construction process, a dry-digging soil-taking method is adopted for construction when a hard clay layer or a hard cemented round gravel layer is encountered. And during sinking construction, observing whether the first cutting edge and the second cutting edge are permeated with water, and if any one of the first cutting edge and the second cutting edge is permeated with water, judging that the water seepage amount is larger.
Optionally, step S501 and step S502 may be further included in step S50.
Step S501, during sinking construction, firstly carrying out soil borrowing construction in a first area in the open caisson, carrying out soil borrowing construction in a second area when the maximum depth of the bottom of a pan at the bottom of the first area is H1, and carrying out soil borrowing construction in a third area when the maximum depth of the bottom of a pan at the bottom of the second area is H2; the value of H1 is greater than that of H2; the first area is one or more compartments in the center of the open caisson; the second area is a plurality of compartments at the left side and the right side of the first area; the third area is a plurality of compartments at the upper side and the lower side of the first area;
and S502, observing and paying attention to the sinking condition of the open caisson when soil taking construction is carried out in the third area, stopping soil taking construction when the open caisson sinks, and continuing to carry out soil taking construction in the third area until the soil body is flush with the second area after the sinking of the open caisson is stopped.
Optionally, the value of H1 is: h1 is more than or equal to 0.5m and less than or equal to 1 m; the value of H2 is more than or equal to 0m and less than or equal to H1 and less than or equal to 0.5 m.
Optionally, in the soil borrowing construction process, the soil borrowing depth difference of the first area, the second area and the third area is controlled within 1 m. When soil taking construction is carried out in the second area and the third area, soil taking is only dug in the area inside the open caisson, and direct excavation and soil taking in the 2m range of the wall of the open caisson is avoided.
Optionally, after the sinking construction is finished, backfilling concrete 13 in the compartment close to one side of the approach bridge; soil 14 is backfilled in the compartment adjacent one side of the main bridge. The concrete is C20 concrete. When the suspension bridge anchorage open caisson is constructed, because the density of concrete is greater than that of soil, one side of the open caisson close to the approach bridge is heavier, and the open caisson can resist overturning.
As shown in fig. 8, a region a in the figure is a first region, a region B is a second region, and a region C is a third region; when a small pan bottom is formed in an area A at the center of the open caisson, the maximum depth of the pan bottom is not more than 1m, soil in an area B is started to form a large pan bottom gradually, soil in an area C is started to be taken when the depth of the pan bottom of the soil in the area B is about 0.5m, the soil in the area C is taken when the soil in the area B is taken, the open caisson sinking condition is noticed, the soil in the area C is continuously taken until the area B is leveled after the open caisson sinking is stopped, and then soil taking in the open caisson compartment is sequentially and circularly performed. The open caisson sinking soil sampling adheres to a 'symmetrical, uniform and synchronous' six-character square rule, and the height difference of each part during soil sampling is controlled within 1 m. Wherein, the region D only takes auxiliary soil sampling and keeps the soil body higher than the blade foot all the time. When soil is taken in the B, C area, only the soil is taken in the inner side area of the open caisson by excavation, and the direct excavation and soil taking in the 2m range of the wall of the open caisson is avoided.
The method breaks through the limitation that the hard plastic cohesive soil area is not suitable for constructing the open caisson foundation, and solves the technical problem of open caisson construction in the hard plastic cohesive soil area. The open caisson bottom section is of a reinforced concrete structure and is provided with a first-level step, and the first cutting edge 9 and the second cutting edge 10 are externally wrapped with steel plates, so that a steel shell structure is avoided, the economy is good, and the soil cutting and sinking capacity is improved; the construction of the bottom section adopts the scheme of tamping a natural foundation and a sand cushion layer, and the scheme of reinforcing a conventional compaction pile foundation and a skid is adopted, so that the engineering cost is saved, and the problem of bottom section cracking caused by uneven skid extraction is avoided; aiming at the characteristics of a hard plastic sticky land layer, a method combining a dry excavation soil-taking method, a flushing and suction mud drainage sinking method and an air suction mud non-drainage sinking method is adopted for sinking, and an air curtain assisted sinking measure is adopted, so that the technical problem of difficult sinking of a hard plastic sticky land area is solved; the 'small pan bottom' soil taking scheme is adopted, so that the sunk well is ensured to sink uniformly, and the sinking quality and safety are improved.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. A hard plastic viscous land area open caisson is characterized by comprising:
a well wall (1);
the partition wall (2) is arranged in the well wall (1) and used for uniformly dividing the open caisson into a plurality of compartments, and a chamfer is arranged at the corner of each compartment;
the first cutting edge (9) is arranged at the bottom of the well wall (1), a first steel plate (3) covers the surface of the first cutting edge (9), and the shape of the first steel plate (3) is the same as that of the first cutting edge (9);
and the second blade foot (10) is arranged at the bottom of the partition wall (2), a second steel plate (11) is covered on the surface of the second blade foot (10), and the shape of the second steel plate (11) is the same as that of the second blade foot (10).
2. The hard plastic sticky land area open caisson according to claim 1, wherein: the thickness of the first steel plate (3) and the second steel plate (11) is 10-20 mm; the distance between the bottom surface of the partition wall (2) and the bottom surface of the second cutting edge (10) is 50 cm.
3. The hard plastic sticky land area open caisson according to claim 1, wherein: the gas supply device is characterized in that a transverse gas supply pipe (5) is buried at the outer side of the well wall (1), a plurality of grooves (4) are formed in the well wall (1) at the outer side of each transverse gas supply pipe (5), each groove (4) is in a quadrangular frustum pyramid shape, the top surfaces of the grooves (4) are in contact with the transverse gas supply pipes (5), and the bottom surfaces of the grooves (4) are arranged on the outer surface of the well wall (1); and the transverse air supply pipe (5) opposite to the top surface of the groove (4) is provided with an air injection hole (6).
4. The hard plastic sticky land area open caisson according to claim 3, wherein: the gas injection holes (6) are arranged on the upper side of the transverse gas supply pipe (5); the bottom surface of the groove (4) is an isosceles trapezoid, and the length of the upper bottom of the isosceles trapezoid formed by the bottom surface is greater than that of the lower bottom; the orthographic projection of the top surface of the groove (4) on the bottom surface is positioned at the lower side of the bottom surface.
5. The hard plastic sticky land area open caisson according to claim 3, wherein: the transverse air supply pipe (5) comprises a plurality of transverse air supply pipes, each transverse air supply pipe (5) is parallel to each other, and each transverse air supply pipe (5) is in hot-melt connection with the longitudinal air supply pipe; the grooves (4) on the outer sides of two adjacent transverse gas supply pipes (5) are arranged at intervals.
6. The hard plastic sticky land area open caisson according to claim 3, wherein: the distance between the top surface and the bottom surface of each groove (4) is 3-5 cm, the distance between two adjacent grooves (4) is 1.0-1.5 m, and 4-6 air injection holes (6) corresponding to each groove (4) are arranged.
7. A method for constructing an open caisson in a hard plastic cohesive soil area is characterized by comprising the following steps:
removing surface layer floating soil, and tamping the foundation pit without the surface layer floating soil;
laying a sand cushion layer in the tamped foundation pit; the sand cushion layer is filled layer by layer, and the medium coarse sand is vibrated and compacted by a vibrating rod;
after the sand cushion is filled, carrying out a bearing capacity experiment;
constructing a first cutting edge (9) and a second cutting edge (10), and backfilling coarse sand in the side surface of each first cutting edge (9) and each second cutting edge (10) and vibrating to compact after the construction of the first cutting edge (9) and the second cutting edge (10) is completed; then pouring the well wall (1) on the basis of the first cutting edge (9) and the second cutting edge (10);
during sinking construction, a dry-excavation soil-taking method is firstly adopted for construction; when the open caisson is below the underground water level and has no water seepage or less water seepage, the construction is carried out by adopting a flushing and sucking mud drainage sinking method; when the open caisson is below the underground water level and the water seepage amount is large, the construction is carried out by adopting an air mud suction non-drainage sinking method; in the sinking construction process, a dry-digging soil-taking method is adopted for construction when a hard clay layer or a hard cemented round gravel layer is encountered.
8. The method for constructing the open caisson in the hard plastic cohesive soil area according to claim 7, wherein the method comprises the following steps:
during sinking construction, firstly carrying out soil taking construction in a first area in the open caisson, carrying out soil taking construction in a second area when the maximum depth of the bottom of a pan at the bottom of the first area is H1, and carrying out soil taking construction in a third area when the maximum depth of the bottom of a pan at the bottom of the second area is H2; the value of H1 is greater than that of H2; the first area is one or more compartments in the center of the open caisson; the second area is a plurality of compartments at the left side and the right side of the first area; the third area is a plurality of compartments at the upper side and the lower side of the first area;
when soil taking construction is carried out in the third area, the observation is carried out to pay attention to the sinking condition of the open caisson, when the open caisson sinks, the soil taking construction is stopped, and after the open caisson sinks to stop, soil taking construction is continued to be carried out in the third area until the soil body is flush with the second area.
9. The method for constructing the open caisson in the hard plastic adhesive land area according to claim 8, wherein the H1 is selected from the following values: h1 is more than or equal to 0.5m and less than or equal to 1 m; the value of H2 is more than or equal to 0m and less than or equal to H2 and less than or equal to 0.5 m.
10. The method for constructing the open caisson in the hard plastic adhesive land area, according to claim 8, is characterized in that: and in the soil borrowing construction process, the soil borrowing depth difference of the first area, the second area and the third area is controlled within 1 m.
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| GB153468A (en) * | 1919-11-24 | 1920-11-11 | Robert Macdonald Wilson | An improved method of application of interstructural tubes to facilitate sinking operations in caissons and wells in subaqueous foundations by means of gas, air, water, or other liquid |
| CN109098201A (en) * | 2018-10-12 | 2018-12-28 | 西南交通大学 | A kind of super plane area portions prestressed concrete well foundation and its construction method |
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