CN108487289B

CN108487289B - Treatment method for attaching bottom of large flat-bottom storage tank to supporting surface of foundation bearing platform

Info

Publication number: CN108487289B
Application number: CN201810182311.2A
Authority: CN
Inventors: 潘前友; 高君丽; 周天龙; 李刚
Original assignee: Cgnpc Uranium Resources Co ltd
Current assignee: Cgnpc Uranium Resources Co ltd
Priority date: 2018-03-06
Filing date: 2018-03-06
Publication date: 2020-04-03
Anticipated expiration: 2038-03-06
Also published as: CN108487289A

Abstract

The invention discloses a treatment method for attaching a base bearing platform supporting surface to a tank bottom of a large-scale storage tank, which comprises the steps of performing secondary grouting on a cavity between a tank body bottom plate and a base bearing platform, and filling the cavity between the tank bottom and the base bearing platform through the secondary grouting to completely attach the tank bottom and the base bearing platform supporting surface; the method comprises the following steps: constructing cofferdams at the periphery of the tank body; drilling grouting holes at certain intervals on a bottom plate of the tank body; selecting an organic composite material Trinicoat PU as a grouting material for grouting; discharging gas remained in a gap between a tank body bottom plate and a foundation bearing platform in the grouting process; and (5) plugging the grouting hole. The technical scheme of the invention solves the difficulty in repairing the large flat-bottom tank, is suitable for treating the gap between the bottom plate of the large tank and the foundation, ensures that the bottom plate of the tank body is uniformly stressed, is convenient to construct, has low cost and obvious economic value.

Description

Treatment method for attaching bottom of large flat-bottom storage tank to supporting surface of foundation bearing platform

Technical Field

The invention relates to the technical field of large-scale tank construction, in particular to a method for processing a tank bottom joint foundation bearing platform supporting surface of a large-scale flat-bottom storage tank, which is generally suitable for processing a gap between a large-scale tank bottom plate and a foundation and ensures that the tank bottom plate is uniformly stressed.

Background

In the construction process of large flat-bottom storage tanks and tank tanks, the welding residual deformation of the bottom plate is large due to the arrangement of the welding seams of the bottom plate and the welding sequence, and the bottom plate of the storage tank is raised and sunken to different degrees after being welded; or the tank body foundation has the problems of unevenness and the like after construction due to design and construction reasons, so that a larger gap is reserved between the tank bottom of the storage tank and the bearing platform supporting surface, the tank bottom of the large flat-bottom storage tank cannot be completely attached to the basic bearing platform supporting surface, and the stress distribution of the tank body bottom plate is influenced.

In order to solve the problems, the conventional common methods mainly comprise two methods, one method is to support the cylinder by adding a temporary support and a stiffening rib, then cut off the bottom plate, adjust the construction sequence of the bottom plate and construct again; the second method is to add stiffening ribs on the upper surface of the bottom plate to reinforce the bottom plate.

In the first method, because the residual stress is large in the welding process of the cylinder, the design of the support and the stiffening ribs are very critical before the bottom plate is cut off, and the roundness of the cylinder is easy to change if the residual stress is not enough; in addition, the construction period is long, the cost is high, and the method is not suitable for repairing after construction is finished.

In the second method, the concave-convex part of the bottom plate is enlarged, so that the welding of the stiffening rib and the bottom plate is difficult to complete in construction, meanwhile, the stiffening rib easily causes the accessory stress of the bottom plate, the stress of the bottom plate is changed, detailed analysis is needed, the repairing difficulty is high, the stress of the bottom plate is uncertain, and in addition, due to the influence of the stiffening rib, the subsequent use is inconvenient, and the tank body is inconvenient to clean.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides a treatment method for attaching the bottom of a large flat-bottom storage tank to the supporting surface of a foundation bearing platform, which is suitable for treating a gap between a large tank bottom plate and a foundation and ensures that the tank bottom plate is stressed uniformly.

The technical scheme provided by the invention is as follows:

a treatment method for attaching a bottom of a large flat-bottom storage tank to a supporting surface of a foundation bearing platform comprises the steps of performing secondary grouting on a gap between a bottom plate of the tank body and the bearing platform, and filling a cavity between the tank bottom and the foundation bearing platform to enable the tank bottom and the supporting surface of the foundation bearing platform to be completely attached; the invention improves the uneven stress distribution of the bottom plate of the tank body caused by the uneven surface of the original bearing platform and the concave-convex bottom of the tank body through grouting, and simultaneously can avoid the vertical displacement of the bottom plate at the gap position caused by the height change of the liquid level of the liquid in the tank body, improve the stress state of the bottom plate and avoid the fatigue of the bottom plate;

the method comprises the following steps:

1) constructing cofferdams at the periphery of the tank body;

according to the storage medium of the tank body, the cofferdam can adopt cement mortar; when the cofferdam is implemented specifically, the tank body is used for storing concentrated sulfuric acid, and the cofferdam is made of acid-resistant daub. The cofferdam aims to prevent slurry from overflowing when the tank bottom is grouted, and the height of the cofferdam is basically equal to the distance between the upper surface of the tank foundation and the bottom plate of the tank. Drilling a plurality of small holes on the cofferdam, uniformly distributing according to a certain distance to be beneficial to gas discharge in the grouting process, and observing whether slurry overflows or not so as to judge the position of the slurry.

2) Drilling holes at certain intervals on a bottom plate of the tank body;

the drilling distance is determined mainly by the fluidity of the grouting material, and is preferably determined experimentally according to the conditions such as the field climate. The spacing between the holes is about 2.0 m and the diameter of the holes is about phi 30 mm.

When the invention is implemented, Trinicoat PU is selected as a grouting material, the material is polyurethane organic compound which is packed by 10 liters, and 2 liters of activating agent is needed to be added before the grouting.

In a specific embodiment, the drilling arrangement is as follows: the diameter of the bottom of the tank is 27.745m, 10 holes are arranged on the circumference with the radius of 2.0, 10 holes are arranged on the circumference with the radius of 4.25m, 10 holes are arranged on the circumference with the radius of 6.5m, 20 holes are arranged on the circumference with the radius of 9.5m, and 20 holes are arranged on the circumference with the radius of 11.5m, so that the distance between the holes is controlled to be about 2 meters approximately, and the grouting material can be ensured to fill the gap between the bottom plate and the bearing platform before solidification.

3) Grouting;

because the grouting material has short solidification time at high temperature, a time period with lower temperature needs to be selected, and then the grouting amount, the grouting speed and the arrangement of resources are noticed, so that the grouting is ensured to be continuously finished at one time, and the interruption is avoided. In addition, in the grouting process, the gas originally retained in the gap between the foundation and the bottom plate needs to be considered and discharged, grouting is the most critical activity in the whole repair, and resources including materials, personnel, equipment, material conveying paths and the like need to be organized.

4) And after grouting is finished, slurry is solidified, namely, the grouting hole is covered by the cover plate after the grouting hole is connected with the peripheral bottom plate by the circular plate through plug welding.

Care needs to be taken during the welding of the circular plates to avoid damage to the grouting material by the weld, since the selected material is easily damaged at the high temperature of the weld.

The fluidity of the grouting material adopted by the invention is deteriorated with the temperature rise, and at the same time, the material can emit heat in the solidification process. Repeated tests prove that the temperature of less than 25 ℃ is a relatively suitable grouting operation temperature. Sealing after grouting, and adopting filling welding or proper cover plate sealing welding after grouting.

Through the treatment steps, the tank bottom of the large flat-bottom storage tank can be tightly attached to the supporting surface of the foundation bearing platform.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a method for processing a joint of a tank bottom and a base bearing platform supporting surface of a large flat-bottom storage tank, which comprises the steps of performing secondary grouting on a gap between a tank bottom plate and a bearing platform, filling a cavity between the tank bottom and the base bearing platform, completely jointing the tank bottom and the base bearing platform supporting surface, avoiding the problem of stress distribution of the tank bottom plate, avoiding vertical displacement of the bottom plate at the gap position caused by the change of the liquid level height of liquid in the tank body due to the tank bottom plate, improving the stress state of the bottom plate and avoiding fatigue of the bottom plate; the technical scheme of the invention is suitable for processing the gap between the bottom plate of the large tank and the foundation, and ensures that the bottom plate of the tank body is uniformly stressed.

The method provided by the invention solves the difficulty in repairing the large flat-bottom tank, and has an obvious effect in practical application; the economic value is obvious; the method of the invention has the following advantages:

due to good material flowability and convenient construction, the assembly of a welding bottom plate by a reworked bottom plate is avoided;

secondly, uncertainty of influence on the stress performance of the bottom plate due to the fact that stiffening ribs are additionally arranged in other methods is avoided;

the construction period is saved, and the influence on the whole project is avoided;

(IV) the cost is lower;

and (V) the stress performance of the repaired tank body is simple, the influence of repair is small, and the functional requirements are met.

Drawings

FIG. 1 is a block flow diagram of the method of the present invention.

FIG. 2 is a schematic diagram of weld placement and welding sequence in an exemplary implementation.

Wherein, (a) is a scene picture of the specific implementation of the welding seam arrangement and the welding sequence; (b) for the original design of a tank bottom plate arrangement schematic diagram, the diameter of a tank bottom plate is 27.745m, the central part R5 is a horizontal circular plate with the diameter of 2.0 m, 40 parts of circular arc-shaped plates (the models are B-1, B-2, B-3 and B-4 respectively) are divided along the circumference, assembly is carried out at two symmetrical positions of the circle center of the bottom plate from outside to inside during welding, and due to large residual deformation in the welding process, the assembled bottom plate has large local bulges, and the highest position reaches 100 mm.

FIG. 3 is a screenshot of the bottom of the can after welding is completed in a particular implementation. FIG. 4 is a screenshot of a grout pipe installation during a specific implementation.

FIG. 5 is a sectional view of a grouting operation performed in a specific implementation process.

FIG. 6 is a sectional view of the seal after grouting is completed in the specific implementation process.

FIG. 7 is a schematic structural diagram of a concrete implementation in which a processed circular plate and a bottom plate are integrally connected by plug welding when a grouting hole is sealed;

wherein, A-the round hole plate for plug welding has the same material and thickness as the tank bottom plate; b, a base plate of the original tank; before welding, a notch angle with the height of 5mm and the angle of 45 degrees is polished on a base plate of an original tank for subsequent plug welding; the distance between the round hole plate and the tank bottom plate is 1-2 mm.

FIG. 8 is a schematic diagram of a structure of a cover plate welded to a circular plate for sealing a grouting hole in an embodiment;

in the figure, A-round hole plate for plug welding; b, a base plate of the original tank; c, a cover plate with the thickness of 10 mm; continuous fillet welds are adopted between the cover plate and the tank bottom plate, and the weld height is 5 mm.

Detailed Description

The invention will be further described by way of examples, without in any way limiting the scope of the invention, with reference to the accompanying drawings.

In the specific installation and implementation process of the large flat-bottom storage tank, the arrangement and welding sequence of the welding seams are generally shown in fig. 2, and as can be seen from fig. 2, the welding seams are radially arranged, so that stress is easily concentrated at the central position during welding; particularly, when the welding sequence is performed from outside to inside, the phenomenon is more obvious; thereby causing the tank bottom to be convex, unable to be attached to the foundation, affecting the stability and the service life of the tank body. The bottom of the can after welding is shown in figure 3. As is evident from FIG. 3, after the can bodies are welded, the bottom of the can is deformed and partially suspended. The situation can cause local frequent deformation of the tank bottom along with the change of the liquid level in the tank in the operation process, thereby damaging the tank bottom.

FIG. 1 is a flow chart of a treatment method for attaching the bottom of a large flat-bottom storage tank to a supporting surface of a basic bearing platform provided by the invention; the specific treatment process comprises the following steps:

1) the tank bottom plate is surveyed and mapped, and the raised part of the tank bottom plate is marked, so that the specific condition of the tank bottom can be found, and the method can be used for estimating the grouting material quantity and judging the grouting effect. The surveying and mapping can be carried out by adopting a total station instrument, and also can be carried out by using an contour instrument;

2) based on the mapping and the tank size, the approximate volume of the cavity is calculated and the amount of grouting material is estimated. Specifically, after drilling, roughly measuring the height of each hollow drum by using a ruler, then averagely taking the height as the size of the hollow drum of the tank bottom plate, and estimating the approximate volume of the cavity by considering the area range of grouting;

3) according to the weld arrangement and the mapping result of the large flat-bottom storage tank, the distance between grouting holes is roughly determined by considering the fluidity of the grouting material, in the embodiment, the organic composite material Trinicoat PU is adopted, and the range which can be covered by each hole during grouting can be roughly known by looking up the performance parameters of the material and the fluidity test under the condition of similar climatic temperature, so that the hole distance is determined.

FIG. 4 is a screenshot of a grout pipe installation during a specific implementation. As can be seen from FIG. 4, the density of the grouting pipes is determined according to actual conditions, and if the cavity part at the bottom of the tank is too large, the distance between the grouting pipes (namely the distance between grouting holes) can be properly increased.

In the embodiment, the distance between grouting holes is determined to be about 2000mm (circumferential direction and radial direction), and the aperture is 25-30 mm; meanwhile, the center of the cylinder body is slightly dense, and the hole spacing can be properly increased along the periphery of the cylinder body (mainly considering that the foundation has a certain gradient).

The selection of the grouting material is very critical, the fluidity of the grouting material is an important factor for selection, and a plurality of experiments are carried out when the material is selected, wherein the experiments comprise Sika slurry material, resin and the like, which are forced to be abandoned due to the short fluidity and solidification time and difficulty in reaching a place to be filled, and the corrosion resistance between the medium in the tank body and the grouting material needs to be considered; of course cost is also a factor that must be considered.

FIG. 5 is a sectional view of a grouting operation performed in a specific implementation process. The fluidity of the grouting material used by us is deteriorated with the increase of temperature, and at the same time, the material emits heat during the solidification process. Repeated tests prove that the temperature lower than 25 ℃ is a relatively proper operating temperature.

4) Welding or bonding a grouting pipe with the diameter of 150-200mm on each grouting hole, wherein the length is about 1000mm, the convenience of operation and the effect of the pressure of the grouting pipe on grouting materials are mainly considered, and a funnel is connected on the grouting pipe;

5) grouting the periphery of the bottom plate of the tank by using cement grouting material (or acid-proof cement), and sealing to prevent grouting material from escaping;

6) preparing grouting material under the environment that the temperature is not higher than 25 ℃, preparing two materials (a barrel of 10 liters of TrinicoatPU is prepared with a 2 liters of keg activating agent, stirring the Trinicoat PU uniformly in the barrel during preparation, then slowly pouring the 2 liters of activating agent into a 10L big barrel), stirring uniformly by a stirrer for no more than 5 minutes, and strictly controlling the stirring time;

7) grouting slurry through the grouting pipes, observing while injecting, paying attention to enable bubbles to escape as much as possible, stopping grouting when the grouting pipes are full, and replacing the next grouting pipe until all the grouting pipes are full of slurry;

8) waiting for the injected slurry to solidify;

9) and detecting whether a cavity still exists by using a knocking method. If yes, supplementary drilling and grouting holes and grouting;

10) and (4) removing the grouting pipe, sealing the grouting hole by using a filling welding method, or plugging and welding by using a proper cover plate, and completing the repair.

In specific implementation, a processed circular plate (with the thickness of 10mm) and a bottom plate are connected into a whole by plug welding, and the welding is as shown in FIG. 7. Then a cover plate (10 mm thick) was welded to the top of the circular plate, as shown in FIG. 8.

11) The effectiveness of grouting can be confirmed through subsequent hydraulic pressure experiments.

Fig. 6 is a screenshot of the seal after grouting, and after grouting, filling welding or sealing welding with a suitable cover plate is adopted.

Through the construction process, secondary grouting is carried out on the gap between the tank bottom plate and the bearing platform, and the cavity between the tank bottom and the foundation bearing platform is filled, so that the supporting surfaces of the tank bottom and the foundation bearing platform are completely attached, the stress distribution problem of the tank bottom plate is avoided, meanwhile, the vertical displacement of the bottom plate at the gap caused by the change of the liquid level height of the liquid in the tank body can be avoided, the stress state of the bottom plate is improved, and the fatigue of the bottom plate is avoided. The technical scheme of the invention is suitable for treating the gap between the bottom plate of the large-scale tank and the foundation, ensures the uniform stress of the bottom plate of the tank body, solves the difficulty of repairing the large-scale flat-bottom tank, and has obvious effect in practical application.

It is noted that the disclosed embodiments are intended to aid in further understanding of the invention, but those skilled in the art will appreciate that: various substitutions and modifications are possible without departing from the spirit and scope of the invention and appended claims. Therefore, the invention should not be limited to the embodiments disclosed, but the scope of the invention is defined by the appended claims.

Claims

1. A treatment method for attaching a base bearing platform supporting surface to a tank bottom of a large storage tank comprises the steps of performing secondary grouting on a cavity between a tank bottom plate and a base bearing platform, and filling the cavity between the tank bottom and the base bearing platform through the secondary grouting to enable the tank bottom and the base bearing platform supporting surface to be completely attached; the method comprises the following steps:

1) constructing cofferdams at the periphery of the tank body, wherein the height of the cofferdams is the same as the distance from the upper surface of the tank body foundation to the bottom plate of the tank body; the cofferdam material adopts cement mortar or acid-resistant cement mortar; drilling a plurality of small holes in the cofferdam for judging the position of the slurry;

2) drilling a plurality of holes on a bottom plate of the tank body to be used as grouting holes; the drill holes are arranged along the circumference of the bottom plate of the tank body, so that the grouting material can fill the cavity between the bottom plate of the tank body and the foundation bearing platform before solidification;

3) grouting a cavity between the tank body bottom plate and the foundation bearing platform, wherein the grouting is continuously completed at one time, and interruption is avoided; selecting an organic composite material Trinicoat PU as a grouting material; discharging gas remained in a gap between a tank body bottom plate and a foundation bearing platform in the grouting process; the grouting comprises the following processes:

31) welding or bonding a grouting pipe on each grouting hole, and connecting a funnel on each grouting pipe;

32) grouting the periphery of the tank bottom plate with cement grouting material or acid-proof cement, and sealing to prevent the grouting material from escaping;

33) preparing a grouting material in an environment with the temperature not higher than 25 ℃, wherein the grouting material is prepared by uniformly stirring the Trinicoat PU in a barrel, slowly pouring an activating agent into the barrel, and uniformly stirring the activating agent and the barrel by using a stirrer; the stirring time is strictly controlled to be not more than 5 minutes;

34) grouting materials are injected through the grouting pipes, bubbles escape in the injecting process, the grouting is stopped when the grouting pipes are filled, and the next grouting pipe is replaced until all the grouting pipes are filled with the grouting materials;

35) waiting for the injected grouting material to solidify;

36) detecting whether a cavity still exists by a tapping method; if so, additionally drilling a grouting hole and grouting;

4) after grouting, blocking grouting holes after the slurry is solidified;

the tank bottom of the large-scale storage tank is completely attached to the supporting surface of the basic bearing platform through the steps.

2. The treating method according to claim 1, wherein in the step 2), the hole interval is determined according to fluidity of the grouting material and climatic conditions; the hole spacing is two meters.

3. The process according to claim 1, wherein the grouting material Trinicoat PU is prepared by mixing 10 liters of polyurethane organic compound with 2 liters of activator before pouring.

4. The process of claim 1 wherein the grouting is carried out at an operating temperature of less than 25 ℃.

5. The treatment method as claimed in claim 1, wherein the grouting hole is sealed by a filling weld or a cover plate after grouting; firstly, a processed circular plate and a tank body bottom plate are connected into a whole through plug welding, and then a cover plate is welded on the circular plate.

6. The process of claim 1 wherein the length of the slurry injection tube is 1000mm and the diameter is 150-200 mm.