1. A method for blocking a seepage channel of a negative pressure barrel foundation is carried out when a negative pressure barrel sinks; the barrel cover of the negative pressure barrel is provided with an exhaust valve, a pump port connected with a submersible pump and a grouting port; characterized in that the plugging method comprises the following steps:

firstly, putting a negative pressure barrel into water by a crane, slowly releasing gas in the negative pressure barrel by using a pre-opened exhaust valve in the putting process, and closing the exhaust valve after the whole negative pressure barrel is put into water; when the bottom of the negative pressure barrel is 1m away from the seabed, stopping the downward placement, sinking the negative pressure barrel by means of self weight until the bottom of the negative pressure barrel is embedded into the seabed mud surface, starting to pump water in the negative pressure barrel by using a submersible pump until the water pressure in the negative pressure barrel is smaller than that outside the negative pressure barrel to form an internal and external water pressure difference, and enabling the negative pressure barrel to penetrate into the seabed mud by means of the internal and external water pressure difference;

when the negative pressure barrel is damaged by seepage, water outside the negative pressure barrel seeps into the negative pressure barrel through the seepage channel, namely the seepage amount is larger than the water pumping amount, so that the internal and external water pressure difference disappears, and the negative pressure barrel cannot sink continuously;

when the water pressure in the negative pressure barrel is balanced with the water pressure outside the negative pressure barrel, stopping injecting water into the negative pressure barrel through the grouting port, and connecting the grouting port with grouting equipment;

grouting into the negative pressure barrel through grouting equipment, wherein the water pressure in the negative pressure barrel is larger than the water pressure outside the negative pressure barrel in the grouting process to form reverse internal and external water pressure difference, observing the reverse internal and external water pressure difference in real time, and recording the reverse internal and external water pressure difference P when the reverse internal and external water pressure difference is stable, namely the grouted slurry is discharged from the negative pressure barrel to the outside of the negative pressure barrel from the inside through a seepage channel at the moment₁；

Step five, stopping grouting for a period of time t, solidifying the grout in the seepage channel, and calculating the time t according to the initial setting time of the grout in the channel;

step six, starting a submersible pump to inject water into the negative pressure barrel, simultaneously keeping a grouting opening open, discharging residual slurry in the negative pressure barrel to the outside of the negative pressure barrel through the grouting opening by injecting water, and keeping the reverse internal and external water pressure difference to be less than P1 in the water injection process;

step seven, repeating the steps four to six n times, so that the reverse internal and external water pressure difference is sequentially increased to P along with the solidification of the slurry poured in the seepage channel for n times₂、P₃、……P_nUntil the reverse internal and external water pressure difference P_nK is more than kXpcr, wherein Pcr is the maximum internal and external water pressure difference required by the negative pressure barrel to overcome the friction resistance and sink, k is a safety coefficient, and the k is 1.2-1.5;

pumping water in the negative pressure barrel by the submersible pump again until the water pressure in the negative pressure barrel is smaller than the water pressure outside the negative pressure barrel, so that negative pressure is formed in the negative pressure barrel, and the negative pressure barrel continuously penetrates to the designed depth by virtue of the negative pressure; the pressure difference between the inner water and the outer water is kept less than Pcr in the whole process of the penetration of the negative pressure barrel.

Background

In ocean engineering, compare in traditional pile foundation, negative pressure bucket basis has several remarkable characteristics: the negative pressure barrel foundation is favored by the ocean community in recent years because of low material and manufacturing cost, short offshore installation period, no need of piling equipment, excellent anti-pulling performance, accurate positioning and the like. However, the control of the installation process of the negative pressure barrel is a main difficult problem which troubles ocean engineering at present.

Deep and thick soft clay with high water content, high compressibility and low strength is distributed on the surface layer of offshore sea area in China, and on the soft clay seabed foundation, a pile foundation needs to penetrate through a soft soil layer to enter a deeper bearing layer, so that the investment is huge and the construction time is long.

The engineering practice of the foundation structure of the domestic negative pressure barrel is less, and the research on the aspect is just started. In the process of installation and penetration of the negative pressure barrel, the key problem to be solved is whether the negative pressure barrel foundation can be quickly and effectively sunk to the preset design depth. When the negative pressure barrel sinks, the barrel sinks by the dead weight of the structure to form a closed space in the barrel body, and then the pump at the top of the barrel pumps water outwards to form negative pressure in the barrel and enable the barrel body to sink through under the action of the pressure difference between the inside and the outside until the preset depth is reached. The pressure difference can generate seepage in a certain range of the foundation of the negative pressure barrel foundation, and if the suction negative pressure is too large, the seepage damage of soil around the barrel wall is easily caused. The disturbance of the soil around the barrel wall can also cause the soil outside the barrel wall to generate soil flowing damage to the barrel. When the seepage damages the inside and outside UNICOM of passageway with the negative pressure bucket, can influence the formation of barrel inside and outside pressure difference, and then the staving both can not continue to sink to appear, also can not be through the ejecting staving of water injection to influence going on smoothly of sinking through the operation, can cause the negative pressure bucket to scrap when serious. In recent years, many foreign research institutions research negative pressure barrels, and obtain qualitative laws with a great number of practical values, but still lack practical tests, and particularly, no solution for seepage damage of a foundation when the negative pressure barrel sinks is provided.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for blocking a seepage channel of a negative pressure barrel foundation, which does not need to search the seepage channel of the negative pressure barrel foundation, has simple method and low cost and can effectively improve the penetration progress of the negative pressure barrel foundation.

The purpose of the invention is realized as follows: a method for blocking a seepage channel of a negative pressure barrel foundation is carried out when a negative pressure barrel sinks; the barrel cover of the negative pressure barrel is provided with an exhaust valve, a pump port connected with a submersible pump and a grouting port; the plugging method comprises the following steps:

firstly, putting a negative pressure barrel into water by a crane, slowly releasing gas in the negative pressure barrel by using a pre-opened exhaust valve in the putting process, and closing the exhaust valve after the whole negative pressure barrel is put into water; when the bottom of the negative pressure barrel is 1m away from the seabed, stopping the downward placement, sinking the negative pressure barrel by means of self weight until the bottom of the negative pressure barrel is embedded into the seabed mud surface, starting to pump water in the negative pressure barrel by using a submersible pump until the water pressure in the negative pressure barrel is smaller than that outside the negative pressure barrel to form an internal and external water pressure difference, and enabling the negative pressure barrel to penetrate into the seabed mud by means of the internal and external water pressure difference;

when the negative pressure barrel is damaged by seepage, water outside the negative pressure barrel seeps into the negative pressure barrel through the seepage channel, namely the seepage amount is larger than the water pumping amount, so that the internal and external water pressure difference disappears, and the negative pressure barrel cannot sink continuously;

when the water pressure in the negative pressure barrel is balanced with the water pressure outside the negative pressure barrel, stopping injecting water into the negative pressure barrel through the grouting port, and connecting the grouting port with grouting equipment;

grouting into the negative pressure barrel through grouting equipment, wherein the water pressure in the negative pressure barrel is larger than the water pressure outside the negative pressure barrel in the grouting process to form reverse internal and external water pressure difference, observing the reverse internal and external water pressure difference in real time, and recording the reverse internal and external water pressure difference when the reverse internal and external water pressure difference is stable, namely the grouted slurry is discharged from the negative pressure barrel to the outside of the negative pressure barrel through the seepage channelTime-reversed internal and external water pressure difference P₁；

Step five, stopping grouting for a period of time t, solidifying the grout in the seepage channel, and calculating the time t according to the initial setting time of the grout in the channel;

step six, starting a submersible pump to inject water into the negative pressure barrel, simultaneously keeping a grouting opening open, discharging residual slurry in the negative pressure barrel to the outside of the negative pressure barrel through the grouting opening by injecting water, and keeping the reverse internal and external water pressure difference to be less than P1 in the water injection process;

step seven, repeating the steps four to six n times, so that the reverse internal and external water pressure difference is sequentially increased to P along with the solidification of the slurry poured in the seepage channel for n times₂、P₃、_……P_nUntil the reverse internal and external water pressure difference P_nK is more than kXpcr, wherein Pcr is the maximum internal and external water pressure difference required by the negative pressure barrel to overcome the friction resistance and sink, k is a safety coefficient, and the k is 1.2-1.5;

pumping water in the negative pressure barrel by the submersible pump again until the water pressure in the negative pressure barrel is smaller than the water pressure outside the negative pressure barrel, so that negative pressure is formed in the negative pressure barrel, and the negative pressure barrel continuously penetrates to the designed depth by virtue of the negative pressure; the pressure difference between the inner water and the outer water is kept less than Pcr in the whole process of the penetration of the negative pressure barrel.

The method for blocking the seepage channel of the negative pressure barrel foundation has the following characteristics:

1. the grouting liquid with long underwater curing time is adopted, water can be driven by the grout under the high water pressure in the negative pressure barrel, the poured grout permeates into a seepage passage outside the negative pressure barrel along with water flow, the water pressure in the negative pressure barrel is continuously reduced by multiple times of grouting, and the grout poured for multiple times gradually permeates into and solidifies from the starting point to the end point of the seepage passage, so that the purpose of plugging the seepage passage is achieved;

2. the method does not need to search a seepage channel of the negative pressure barrel foundation, has less construction technical equipment, simple method and low cost, and is suitable for underground foundations with concealed seepage channels;

3. the sinking and penetrating progress of the negative pressure barrel foundation can be effectively improved, the smooth construction is ensured, and the surrounding environment is hardly influenced.

Drawings

FIG. 1 is a schematic block diagram of the method for blocking the seepage passage of the base of the negative pressure barrel according to the present invention;

FIG. 2 is a graph showing the time-dependent change of the difference between the internal and external water pressures in the seventh step of the present invention.

Detailed Description

The invention will be further explained with reference to the drawings.

The method for blocking the seepage channel of the negative pressure barrel foundation is carried out when the negative pressure barrel sinks; an exhaust valve, a pump port 2 connected with a submersible pump and a grouting port 3 (see figure 1) are arranged on a barrel cover of the negative pressure barrel 1;

the invention discloses a method for blocking a seepage channel of a negative pressure barrel foundation, which comprises the following steps:

firstly, putting a negative pressure barrel into water by a crane, slowly releasing gas in the negative pressure barrel by using a pre-opened exhaust valve in the putting process, and closing the exhaust valve after the whole negative pressure barrel is put into water; when the bottom of the negative pressure barrel is 1m away from the seabed, stopping the downward placement, sinking the negative pressure barrel by means of self weight until the bottom of the negative pressure barrel is embedded into the seabed mud surface, starting to pump water in the negative pressure barrel by using a submersible pump until the water pressure in the negative pressure barrel is smaller than that outside the negative pressure barrel to form an internal and external water pressure difference, namely the inside of the barrel is negative pressure, and the negative pressure barrel penetrates into the seabed mud by means of the internal and external water pressure difference;

when the negative pressure barrel is damaged by seepage, water outside the negative pressure barrel seeps into the negative pressure barrel through the seepage channel, namely the seepage amount is larger than the water pumping amount, so that the internal and external water pressure difference disappears, and the negative pressure barrel cannot sink continuously;

when the water pressure in the negative pressure barrel is balanced with the water pressure outside the negative pressure barrel, stopping injecting water into the negative pressure barrel through the grouting port, and connecting the grouting port with grouting equipment;

grouting into the negative pressure barrel through grouting equipment, wherein the water pressure in the negative pressure barrel is larger than the water pressure outside the negative pressure barrel in the grouting process to form reverse internal and external water pressure difference, and observing the reverse internal and external water pressure difference in real timeWhen the reverse internal and external water pressure difference is stable, namely the filled slurry is discharged from the negative pressure barrel to the outside of the negative pressure barrel from the inside of the negative pressure barrel through the seepage channel, the reverse internal and external water pressure difference P is recorded at the moment₁；

Step five, stopping grouting for a period of time t, and solidifying the grout in the seepage passage, wherein the time t is calculated according to the initial setting time of the grout; the time t is required from the liquid state of the poured slurry to the loss of fluidity and then to the solidification process of gradually increasing strength, the solidification process of the ordinary cement slurry needs several hours, if the admixture is added, the solidification process can be accelerated, and the specific solidification time is adjusted according to the operation conditions;

step six, in order to remove residual slurry in the negative pressure barrel, a submersible pump is started to inject water into the negative pressure barrel, a grouting opening is kept opened at the same time to serve as a discharge channel of the residual slurry in the negative pressure barrel, the residual slurry in the negative pressure barrel is discharged out of the negative pressure barrel through the grouting opening by water injection, the reverse internal and external water pressure difference is kept to be smaller than P1 in the water injection process, and the seepage channel is guaranteed not to be punctured again due to water injection into the negative pressure barrel;

step seven, repeating the steps four to six n times, and sequentially increasing the reverse internal and external water pressure difference to P2, P3 and … … Pn (see figure 2) after the slurry poured into the seepage channel for n times is solidified until the reverse internal and external water pressure difference Pn is larger than k multiplied by Pcr, wherein Pcr is the maximum internal and external water pressure difference required by the negative pressure barrel to overcome the friction resistance and sink and is calculated by a negative pressure barrel negative pressure sinking static force analysis theory, k is a safety coefficient, and the selection is generally carried out according to the geological conditions of the sea bottom and is 1.2-1.5;

pumping water in the negative pressure barrel by the submersible pump again until the water pressure in the negative pressure barrel is smaller than the water pressure outside the negative pressure barrel, so that negative pressure is formed in the negative pressure barrel, and the negative pressure barrel continuously penetrates to the designed depth by virtue of the negative pressure; the pressure difference between the inner water and the outer water is kept less than Pcr in the whole process of the penetration of the negative pressure barrel.

The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention, and should be defined by the claims.