CN114808926A

CN114808926A - Construction device for building underground space under existing independent foundation

Info

Publication number: CN114808926A
Application number: CN202210637901.6A
Authority: CN
Inventors: 何晓彤; 刘保县; 黄尚珩; 舒志乐; 冉续; 李�杰
Original assignee: Chengdu Third Construction Engineering Co ltd Of Cdceg
Current assignee: Chengdu Third Construction Engineering Co ltd Of Cdceg
Priority date: 2022-06-08
Filing date: 2022-06-08
Publication date: 2022-07-29
Anticipated expiration: 2042-06-08
Also published as: CN114808926B

Abstract

The invention belongs to the field of underground space building, and particularly relates to a construction device for building an underground space under the condition of an existing independent foundation, which comprises a pile body and is characterized in that: the pile body is hollow structure, and its side is provided with a plurality of filtration pores, and is a plurality of the filtration pore is followed the pile body axial distributes, the pile body bottom is provided with the drill bit, still including installing the support body on the basis, be provided with elevating gear and drive arrangement on the support body, the rotatable connection limiting plate of elevating gear output, the limiting plate cover is established on the pile body, and connect the pile body, drive arrangement connects the limiting plate for the drive the limiting plate rotates, has the beneficial effect that can avoid the pile body fracture, reduce the influence to the soil body structure, the cascaded of the pile body of being convenient for stretches into and the longer length of adaptation pile body.

Description

Construction device for building underground space under existing independent foundation

Technical Field

The invention belongs to the field of underground space building, and particularly relates to a construction device for building an underground space under an existing independent foundation.

Background

The anchor rod static pressure pile is a pile pressing implemented by utilizing the counter force provided by the anchor rod anchored in the original foundation, and is mainly used for reinforcing the foundation, such as a static pressure precast pile which is mainly applied to a soft soil foundation.

Because the static pressure pile is usually a hollow cylinder structure, in the pile sinking process, the pile tip directly leads the soil body to generate punching damage, and the direct shearing damage along the soil body of the pile body is accompanied or firstly generated, in the process, pore water and underground water in the soil body form uneven water head under the punching shearing and extruding action to generate over-pore water pressure, the soil body structure is disturbed, and if the water body in the soil body is unevenly distributed, the static pressure pile can generate a certain amount of deflection under the action of the water pressure, which is not beneficial to the verticality of the static pressure pile.

Disclosure of Invention

The invention aims to provide a construction device for building an underground space under the existing independent foundation, which aims to solve the problems in the prior art and adopts the technical scheme that:

the utility model provides a construction equipment of building underground space under existing independent foundation, includes the pile body, its characterized in that: the pile body is of a hollow structure, a plurality of filter holes are formed in the side face of the pile body, the filter holes are distributed along the axial direction of the pile body, and a drill bit is arranged at the bottom of the pile body;

still including installing the support body on the basis, be provided with elevating gear and drive arrangement on the support body, the rotatable connection limiting plate of elevating gear output, the limiting plate cover is established on the pile body, and connect the pile body, drive arrangement connects the limiting plate is used for the drive the limiting plate rotates.

Furthermore, still including setting up the internal drinking-water pipe of stake, the drinking-water pipe top extends the stake body, and is connected with the pump body.

Furthermore, the limiting plate is of a circular ring structure, the inner side of the limiting plate is provided with a sliding hole, a bolt is slidably arranged in the sliding hole, and one end, far away from the limiting plate, of the bolt is inserted into the filter hole;

limiting plate top rotatable coupling adapter sleeve, the adapter sleeve is established on the pile body, and the top is connected the drive arrangement output, the adapter sleeve bottom is connected the bolt is used for promote when drive arrangement reverses the bolt breaks away from the filtration pore to promote when corotation the bolt inserts the filtration pore.

Further, the bottom of the connecting sleeve is fixed and concentrically provided with a fixing ring, and the fixing ring is provided with an arc-shaped hole and is eccentrically arranged with the fixing ring;

the top of limiting plate is provided with the intercommunication the spacing groove of slide opening, the connection regulation pole can be dismantled to the bolt, it passes to adjust the pole the spacing groove just is located the arc is downthehole.

Further, gu fixed ring is provided with the ring channel all around, be provided with the snap ring in the ring channel, the connection lifter plate can be dismantled to the snap ring, the lifter plate is the loop configuration, and inboard all around is provided with the annular chamber, gu fixed ring's all around rotatable setting is in the annular chamber, the top fixed connection of lifter plate the elevating gear output.

Furthermore, the circumferential surface of the limiting plate is connected with the inner wall of the annular cavity through a ratchet mechanism, so that the limiting plate is clamped when the driving device rotates reversely.

Furthermore, the ratchet mechanism comprises a ratchet part fixedly arranged on the circumferential surface of the limiting plate, through holes communicated with the annular cavity are radially arranged on the lifting plate, and sliding pins are arranged in the through holes and are connected with the lifting plate through springs.

Further, the support body is including installing bottom plate on the basis, bracing piece fixed connection backup pad is passed through to the bottom plate top, the limiting plate is located the backup pad with between the bottom plate, the pile body passes the bottom plate, the adapter sleeve top is passed the backup pad, elevating gear installs in the backup pad, its output passes backup pad and fixed connection the lifter plate.

Furthermore, the driving device is installed on a motor at the top of the supporting plate in a wrapping mode, an output shaft of the motor is fixedly connected with a driving gear, and a gear sleeve meshed with the driving gear is sleeved on the connecting sleeve.

Furthermore, the bolt is provided with a plurality of around the limiting plate, the filtration pore in the horizontal direction with what the bolt corresponds is provided with a plurality of.

The invention has the following beneficial effects: the lifting device pushes the limiting plate to move up and down, the limiting plate is connected with the pile body and simultaneously inserts the pile body into the soil body continuously downwards, and in the moving process, the driving device pushes the limiting plate to rotate so as to drive the pile body to rotate together, so that the drill bit continuously extends downwards into the soil body, meanwhile, underground water and pore water in the soil body enter the pile body through the filter holes under the action of pressure difference The pile body is separated from the filter hole, so that the pile body can be conveniently extended in a stepped manner, and the requirements of longer length and deeper position of the pile body can be conveniently met.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is an enlarged view of the point A in FIG. 1;

FIG. 3 is a schematic diagram illustrating the position of the limiting plate being raised to the highest position;

FIG. 4 is a schematic view of an arcuate aperture;

FIG. 5 is a schematic view of the connection relationship between the limiting plate and the lifting plate;

fig. 6 is a schematic view of the connection relationship of the motor.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to fig. 1 to 6 in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, are merely for convenience of description of the present invention, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and thus, are not to be construed as limiting the present invention.

The utility model provides a construction equipment of building underground space under existing independent foundation, includes pile body 3, its characterized in that: the pile body 3 is of a hollow structure, a plurality of filtering holes 4 are formed in the side face of the pile body 3, the filtering holes 4 are distributed along the axial direction of the pile body 3, and a drill bit is arranged at the bottom of the pile body 3;

still including installing the support body on basis 1, be provided with elevating gear 9 and drive arrangement on the support body, the rotatable connection limiting plate 14 of elevating gear 9 output, limiting plate 14 cover is established on pile body 3, and connect pile body 3, drive arrangement connects limiting plate 14 is used for the drive limiting plate 14 rotates.

As shown in fig. 1, the pile body 3 is a static pressure pile, which is vertically arranged, the filtering holes 4 are distributed in a ring array around the pile body 3 in the horizontal direction, a plurality of filtering holes are distributed side by side in the vertical direction, the bottom of the frame body is installed on the foundation 1 through anchor rods, the foundation 1 is the original foundation of the building, the pile body 3 is preset with the pile holes, the pile body 3 passes through the pile holes and is inserted into the soil body 2 below the foundation 1, the lifting device 9 can be a hydraulic cylinder in the prior art, and a plurality of the filtering holes are symmetrically arranged on both sides of the pile body 3, which achieves the purpose of lifting, the limiting plate 14 moves up and down, the limiting plate 14 is connected with the pile body 3 and simultaneously inserts the pile body 3 into the soil body 2 continuously, and in the moving process, the driving device pushes the limiting plate 14 to rotate, so that the pile body 3 is driven to rotate together, and further, the drill bit continuously extends into the soil body 2 downwards, and at the same time, under the pressure of the pile body 3 extruding the soil body, underground water and pore water in the soil body 2 enter the pile body 3 through the filter holes 4 under the action of pressure difference, and when the concrete implementation is carried out, the rotation of the pile body 3 is slow rotation, compared with the prior art, the pile body 3 rotates while being pressed down, and stably sinks under the action of a drill bit, so that the pile body can be prevented from being broken, the construction process is more stable, the underground water and the pore water can be discharged into the pile body 3, the influence on the soil body structure is further reduced, the stress on the peripheral surface of the pile body 3 is uniform, and the deflection caused by the fact that the pile body 3 is horizontally stressed by nonuniform pressure is avoided.

Further, still including setting up the drinking-water pipe 28 in the pile body 3, the drinking-water pipe 28 top extends the pile body 3, and is connected with the pump body.

Specifically, the pump body is in the prior art, and can be a slurry pump, and water and slurry accumulated in the pile body 3 are pumped out, so that a negative pressure environment is formed in the pile body 3 under the action of the soil body 2, and underground water and pore water can enter the pile body 3 conveniently.

Furthermore, the limiting plate 14 is of a circular ring structure, the inner side of the limiting plate is provided with a sliding hole 16, a bolt 13 is slidably arranged in the sliding hole 16, and one end of the bolt 13, which is far away from the limiting plate 14, is inserted into the filtering hole 4;

limiting plate 14 top rotatable coupling adapter sleeve 10, adapter sleeve 10 cover is established on the pile body 3, and the top is connected the drive arrangement output, adapter sleeve 10 bottom is connected bolt 13 is used for drive arrangement promotes when reversing bolt 13 breaks away from filtration pore 4 to promote when corotation bolt 13 inserts filtration pore 4.

Referring to fig. 2, the sliding hole 16 and the plug 13 are located in the radial direction of the position-limiting plate 14, one end of the plug 13 extends from the inner side of the position-limiting plate 14 and is inserted into one of the filtering holes 4, the diameter of the filtering hole 4 is larger than that of the plug 13 to facilitate positioning, the connecting sleeve 10 is in a cylindrical structure and is in clearance fit with the pile body 3 to facilitate lifting of the connecting sleeve 10, in particular, the lifting device 9 pushes the position-limiting plate 14 to lift the connecting sleeve 10, when the lifting device 9 pushes the position-limiting plate 14 to move from top to bottom, the driving device keeps rotating forward, the plug 13 is always located in the filtering hole 4, and then the plug 13 transmits circumferential torque and downward pressure to the pile body 3 to make the pile body 3 go deep downward while rotating, when the lifting device 9 is located at the maximum stroke, the position of the position-limiting plate 14 is the lowest, at this time, the lifting device 9 stops, the driving device rotates backward to make the plug 13 separate from the filtering hole 4, and after the bolt 13 breaks away from the filtering hole 4, the driving device stops, then the lifting device 9 moves upwards again to drive the limiting plate 14 and the connecting sleeve 10 to move upwards, when the connecting sleeve 10 moves upwards, the pile body 3 is static, then the lifting device 9 is in the minimum stroke, the height of the limiting plate 14 is highest, at the moment, the bolt 13 is just aligned to the other filtering hole 4 above, at the moment, the driving device rotates forwards again to enable the bolt 13 to be inserted into the filtering hole 4 again, then the lifting device 9 pushes the pile body 3 downwards to go deep, and the reciprocating operation is carried out, so that the pile body 3 can go deep downwards in a stepped mode continuously.

Further, the bottom of the connecting sleeve 10 is fixed and concentrically provided with a fixing ring 12, and the fixing ring 12 is provided with an arc-shaped hole 22 and is eccentrically arranged with the fixing ring 12;

the top of the limiting plate 14 is provided with a limiting groove 17 communicated with the sliding hole 16, the bolt 13 is detachably connected with an adjusting rod 18, and the adjusting rod 18 penetrates through the limiting groove 17 and is located in the arc-shaped hole 22.

As shown in fig. 4, one end of the arc hole 22 is close to the center of the fixed ring 12, and the other end is far from the center of the fixed ring 12, when the fixed ring 12 rotates, the arc hole 22 pushes the adjusting rod 18 to move along the inner wall surface of the arc, and then the bolt 13 moves, in fig. 4, when the driving device rotates positively, the fixed ring 12 rotates clockwise, and then the adjusting rod 18 moves towards the direction close to the center of the fixed ring 12, and then the bolt 13 is pushed to insert into the filter hole 4, when the driving device rotates negatively, the fixed ring 12 rotates counterclockwise, and the bolt 13 is far away from the center of the fixed ring 12 and is separated from the filter hole 4.

In addition, the adjusting rod 18 is provided with a screw 19, the screw 19 is concentric with the adjusting rod 18, and the bottom of the screw 19 is in threaded connection with the plug 13 so as to achieve the purpose of detachable connection, and the fixing ring 12 and the bottom of the connecting sleeve 10 are integrally formed and can also be fixedly connected by two parts.

Through the rotation of drive arrangement drive adapter sleeve 10, not only realized the rotation of pile body 3, can also promote bolt 13 and insert, break away from filtration pore 4 to the cascaded of pile body 3 stretches into, the longer length of the adaptation pile body 3 of being convenient for and the position demand of deepening.

Further, solid fixed ring 12 is provided with the ring channel all around, be provided with snap ring 20 in the ring channel, snap ring 20 can be dismantled and connect lifter plate 8, lifter plate 8 is the loop configuration, and inboard all around is provided with annular chamber 15, gu fixed ring 12 global rotatable setting is in the annular chamber 15, the top fixed connection of lifter plate 8 the 9 outputs of elevating gear.

Specifically, the ring channel is around the global round setting of solid fixed ring 12, with solid fixed ring 12 concentric, snap ring 20 is the loop configuration, the screwed connection fixing base 21 is passed through to its bottom, fixing base 21 is the loop configuration, in solid fixed ring 12 week, it can rotate on snap ring 20, in the vertical direction, the spacing solid fixed ring 12 of snap ring 20, and then can realize that limiting plate 14 drives solid fixed ring 12 and adapter sleeve 10 and goes up and down, and can make solid fixed ring 12 relative limiting plate 14 rotate, thereby realize promoting the purpose that bolt 13 moved.

Further, the circumferential surface of the limiting plate 14 is connected with the inner wall of the annular cavity 15 through a ratchet mechanism, so that the limiting plate 14 is clamped when the driving device rotates reversely.

Further, the ratchet mechanism comprises a ratchet part 23 fixedly arranged on the circumferential surface of the limiting plate 14, a through hole communicated with the annular cavity 15 is radially arranged on the lifting plate 8, a sliding pin 24 is arranged in the through hole, and the sliding pin 24 is connected with the lifting plate 8 through a spring 25.

Specifically, the limiting plate 14 is in a circular ring structure and is concentric with the fixing ring 12 and the pile body 3, the limiting plate 14 and the ratchet part 23 form a ratchet shape together, as shown in fig. 5, the annular chamber 15 and the ratchet portion 23 are shown in dotted lines, one end of the slide pin 24 extends out of the lifting plate 8, and a limit part is fixedly arranged, a spring 25 is sleeved on the sliding pin 24, one end of the spring is abutted against the limit part, the other end of the spring can be fixedly connected with the circumferential surface of the lifting plate 8 through welding and the like, the other end of the sliding pin 24 is inserted into the annular cavity 15 and is positioned in the tooth gap of the ratchet part 23, when the driving device rotates forwards and the fixing ring 12 rotates clockwise, the limiting plate 14 can rotate, further, torque is transmitted to the pile body 3 through the latch 13, and when the driving device is reversely rotated and the fixed ring 12 is rotated counterclockwise, the slide pin 24 abuts against the ratchet portion 23, so that the fixing ring 12 cannot rotate and the fixing ring 12 drives the latch 13 to disengage from the filter hole 4.

In addition, the fixed plate is passed through bolted connection in the bottom of lifter plate 8, and lifter plate 8 global is provided with annular gap, and annular gap's opening is down, forms annular chamber 15 with the up end of fixed plate jointly, through the dismantlement of fixed plate to limiting plate 14 is in the installation.

Further, the support body is including installing bottom plate 5 on the basis 1, 6 fixed connection backup pads 7 are passed through to bottom plate 5 top, limiting plate 14 is located backup pad 7 with between the bottom plate 5, pile body 3 passes bottom plate 5, the adapter sleeve 10 top is passed backup pad 7, elevating gear 9 is installed in backup pad 7, its output passes backup pad 7 and fixed connection lifter plate 8.

Specifically, 5 bottoms of bottom plate are passed through the stock and are installed at basic 1 up end, backup pad 7 is parallel with bottom plate 5, bracing piece 6 evenly is provided with a plurality of, be provided with the slide opening with bracing piece 6 adaptation on the lifter plate 8, bracing piece 6 is located the slide opening, and then make bracing piece 6 retrain lifter plate 8 in the horizontal direction, guarantee the vertical degree of lift, the locating hole has been seted up down on the bottom plate 5, the diameter and the pile body 3 adaptation of locating hole down, the last locating hole has been seted up on backup pad 7, the diameter of going up the locating hole is greater than adapter sleeve 10, adapter sleeve 10 extends from last locating hole.

Further, the driving device comprises a motor 26 mounted at the top of the supporting plate 7, an output shaft of the motor 26 is fixedly connected with a driving gear 27, and a gear sleeve 11 meshed with the driving gear 27 is sleeved on the connecting sleeve 10.

As shown in fig. 1 and 6, specifically, the gear sleeve 11 is fixedly connected with the connecting sleeve 10, the vertical height of the gear sleeve 11 is equal to that of the connecting sleeve 10, the motor 26 is mounted on the top of the supporting plate 7 through a bracket, and since the motor 26 drives the connecting sleeve 10 to rotate slowly, when the limiting plate 14 and the lifting plate 8 are lifted, the gear sleeve 11 can be meshed with the driving gear 27 without affecting the lifting of the gear sleeve 11 and the connecting sleeve 10.

Further, the inserted pin 13 is provided with a plurality of pins around the limiting plate 14, and the filtering holes 4 are provided with a plurality of pins 13 in the horizontal direction.

Specifically, the sliding hole 16, the limiting groove 17, the adjusting rod 18 and the arc-shaped hole 22 are correspondingly provided with a plurality of bolts 13.

In addition, after pile body 3 sinks to target in place, pour into the concrete into between pile hole and pile body 3 upper wall face, and pour into the concrete into at the inside concrete into of pile body 3, the concrete in pile body 3 passes through filtration pore 4 and the downthehole concrete intercommunication of pile, so after the concrete sets and fixes, the inside and outside concrete of pile body 3 forms a whole and fixes pile body 3 and basis 1, compare prior art and only form the concrete layer structure at pile body 3 global, the steadiness of being connected between pile body 3 and the basis 1 that can be very big improvement.

When the underground space is built under the existing independent foundation, the following method can be adopted:

s1, detecting and reinforcing the existing building;

s2, constructing a support system and an underground continuous wall;

s3, excavating backfill above the bottom surface of the foundation 1, and forming pile holes;

s4, anchor rod construction, fixing the bottom plate 5, installing the pile body 3, inserting the pile body into the soil body 2, and then injecting concrete;

s5, earth excavation;

s6, constructing a top plate and a partition plate of the basement;

after the construction of basement earthwork engineering is completed, basement baffle construction work needs to be carried out immediately to guarantee the safety of foundation pit, basement roof work progress contains basement structure post work progress, and pile body 3 in this process will be the basement structure post with the basement, and superstructure load is directly given the stake-raft foundation of below by basement structure post.

The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various changes, modifications, alterations, and substitutions which may be made by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. The utility model provides a construction equipment of building underground space under existing independent foundation, includes pile body (3), its characterized in that: the pile body (3) is of a hollow structure, a plurality of filter holes (4) are formed in the side face of the pile body, the filter holes (4) are axially distributed along the pile body (3), and a drill bit is arranged at the bottom of the pile body (3);

still including installing the support body on basis (1), be provided with elevating gear (9) and drive arrangement on the support body, rotatable connection limiting plate (14) of elevating gear (9) output, limiting plate (14) cover is established on pile body (3), and connects pile body (3), drive arrangement connects limiting plate (14) are used for the drive limiting plate (14) rotate.

2. The construction apparatus for constructing an underground space on an existing independent basis as claimed in claim 1, wherein: still including setting up drinking-water pipe (28) in pile body (3), drinking-water pipe (28) top extends pile body (3), and is connected with the pump body.

3. The construction apparatus for constructing an underground space on an existing independent basis as claimed in claim 1, wherein: the limiting plate (14) is of a circular ring structure, a sliding hole (16) is formed in the inner side of the limiting plate, a bolt (13) is slidably arranged in the sliding hole (16), and one end, far away from the limiting plate (14), of the bolt (13) is inserted into the filtering hole (4);

limiting plate (14) top rotatable coupling adapter sleeve (10), adapter sleeve (10) cover is established on pile body (3), and the top is connected the drive arrangement output, adapter sleeve (10) bottom is connected bolt (13), be used for promote during the drive arrangement reversal bolt (13) break away from filtration hole (4), and promote during corotation bolt (13) insert filtration hole (4).

4. A construction apparatus for constructing an underground space on an existing independent basis as claimed in claim 3, wherein: the bottom of the connecting sleeve (10) is fixedly and concentrically provided with a fixing ring (12), and an arc-shaped hole (22) is formed in the fixing ring (12) and is eccentrically arranged with the fixing ring (12);

the top of limiting plate (14) is provided with intercommunication limiting groove (17) of slide opening (16), regulation pole (18) can be dismantled in connection in bolt (13), adjust pole (18) and pass limiting groove (17) and be located in arc hole (22).

5. The construction apparatus for constructing an underground space on an existing independent basis as set forth in claim 4, wherein: the utility model discloses a lifting device, including solid fixed ring (12), snap ring (20), lifter plate (8) can be dismantled and connection to solid fixed ring (12) global, the lifter plate (8) are the loop configuration, and the inboard global is provided with annular chamber (15), the global rotatable setting of solid fixed ring (12) is in annular chamber (15), the top fixed connection of lifter plate (8) elevating gear (9) output.

6. The construction apparatus for constructing an underground space on an existing independent basis as set forth in claim 5, wherein: the circumferential surface of the limiting plate (14) is connected with the inner wall of the annular cavity (15) through a ratchet mechanism, so that the limiting plate (14) is clamped when the driving device rotates reversely.

7. The construction apparatus for constructing an underground space on an existing independent basis as set forth in claim 6, wherein: the ratchet mechanism comprises ratchet parts (23) fixedly arranged on the circumferential surface of the limiting plate (14), through holes communicated with the annular cavity (15) are radially arranged on the lifting plate (8), sliding pins (24) are arranged in the through holes, and the sliding pins (24) are connected with the lifting plate (8) through springs (25).

8. The construction apparatus for constructing an underground space on an existing independent basis as set forth in claim 5, wherein: the support body is including installing bottom plate (5) on basis (1), bracing piece (6) fixed connection backup pad (7) are passed through to bottom plate (5) top, limiting plate (14) are located backup pad (7) with between bottom plate (5), pile body (3) pass bottom plate (5), adapter sleeve (10) top is passed backup pad (7), elevating gear (9) are installed in backup pad (7) are last, and its output passes backup pad (7) and fixed connection lifter plate (8).

9. The construction apparatus for constructing an underground space on an existing independent basis as claimed in claim 8, wherein: the drive arrangement package is installed motor (26) at backup pad (7) top, motor (26) output shaft fixed connection driving gear (27), the cover is equipped with on adapter sleeve (10) with driving gear (27) engaged with tooth cover (11).

10. A construction apparatus for constructing an underground space on an existing independent basis as claimed in claim 3, wherein: the bolt (13) is provided with a plurality of around limiting plate (14), filtration pore (4) on the horizontal direction with bolt (13) correspond be provided with a plurality of.