Submerged foundation sinking sand gushing risk identification and control method

Abstract

The invention relates to the technical field of submerged foundation construction, in particular to a submerged foundation sinking sand gushing risk identification and control method. Comprising the steps that in the sinking process of the submerged foundation, the critical burial depth of a blade foot is calculated based on the internal and external water level elevation of the submerged foundation and the internal soil body characteristics of the submerged foundation; identifying whether a sand gushing risk exists or not based on the current actual burial depth of the blade foot and the critical burial depth of the blade foot; and when it is identified that the sand gushing risk exists, steel sheet piles are inserted into the submerged foundation so as to control sand gushing. According to the method, a novel submerged foundation structure is constructed, the critical blade foot burial depth considering the influence of the difference between the inner water head and the outer water head of the submerged foundation can be calculated, and quantitative recognition and early warning of the sand gushing risk are achieved; the steel sheet piles are arranged in the submerged foundation in a driving mode, the effect of increasing the blade foot burial depth is achieved, and the sand gushing risk of the submerged foundation is well controlled; the method can be applied to multiple engineering scenes such as open caissons, cofferdams and pipe piles for soil taking sinking.

Description

Technical Field

[0001] The invention relates to the technical field of sunken foundation construction, and in particular to a method for identifying and controlling the risk of subsidence and sand gushing from a sunken foundation. Background Art

[0002] The sunken foundation is widely used due to its advantages such as high structural rigidity, simple construction process and good economy. However, during the excavation and sinking construction of the sunken foundation, especially when the sunken foundation is difficult to sink, if the end soil is excavated or the water level inside the sunken foundation is lowered to assist the sinking in order to continue the sinking of the sunken foundation, when the soil at the blade foot of the sunken foundation is over-excavated or the water level inside the sunken foundation is lower than the external water level, the sunken foundation is prone to sand inrush. That is, the external soil of the sunken foundation suddenly surges in, causing the sunken foundation to tilt, crack, and even cause casualties, which is difficult to effectively identify during the traditional sunken foundation construction process. In terms of sand inrush control of the sunken foundation, due to the large thickness of the well wall and the large end resistance, it is difficult to achieve a reliable burial depth of the well wall blade, which leads to a lack of effective control methods for sand inrush of the sunken foundation. Summary of the invention

[0003] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology and provide a method for identifying and controlling the risk of sand gushing during submerged foundation sinking.

[0004] The technical solution of the present invention is: a method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation, comprising:

[0005] During the sinking process of the sunken foundation, the critical burial depth of the blade foot is calculated based on the internal and external water level elevations of the sunken foundation and the soil characteristics inside the sunken foundation.

[0006] Based on the actual burial depth of the blade foot and the critical burial depth of the blade foot, identify whether there is a risk of sand inrush;

[0007] When the risk of sand inrush is identified, steel sheet piles are inserted into the sunken foundation to control the sand inrush.

[0008] According to a method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation provided in the present application, the method for calculating the critical burial depth of the blade foot includes: calculating the critical burial depth of the blade foot according to the following formula:

[0009]

[0010] Where: D2-critical embedding thickness of the inner edge of the sunken foundation (m);

[0011] γ m1 - Weight of soil above the bottom of the outer blade of the sunken foundation (kN / m 3 );

[0012] γm2 - Weight of soil above the bottom of the inner blade of the sunken foundation (kN / m 3 );

[0013] γ w - Weight of water (kN / m 3 );

[0014] Δh-water head difference between inside and outside of the submerged foundation (m);

[0015] h-sunken foundation depth (m);

[0016] N c 、N q - bearing capacity coefficient;

[0017] c-cohesion of soil (kPa);

[0018] - Angle of internal friction (°).

[0019] According to a method for identifying and controlling the risk of sand gushing during sinking of a submerged foundation provided in the present application, the method for identifying whether there is a risk of sand gushing includes: when the actual burial depth of the blade foot is not greater than a set multiple of the critical burial depth of the blade foot, judging that the current submerged foundation has a risk of sand gushing; the set multiple is greater than 1.

[0020] According to a method for identifying and controlling the risk of sand gushing from subsidence of a submerged foundation provided in the present application, when the actual burial depth of the blade foot is not greater than the product of the first multiple and the critical burial depth of the blade foot, a red warning for sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the first multiple and the critical burial depth of the blade foot and is not greater than the product of the second multiple and the critical burial depth of the blade foot, an orange warning for sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the second multiple and the critical burial depth of the blade foot and is not greater than the product of the third multiple and the critical burial depth of the blade foot, a yellow warning for sand gushing is issued; the third multiple is greater than the second multiple, greater than the first multiple, and greater than or equal to 1.

[0021] According to a method for identifying and controlling the risk of sinking and sand gushing of a submerged foundation provided in the present application, the method for inserting steel sheet piles into the submerged foundation comprises: inserting steel sheet piles into the submerged foundation based on a reserved groove section vertically penetrating the submerged foundation along the lower part of the submerged foundation, and adjusting the driving depth of the steel sheet piles based on the actual burial depth of the blade foot and the critical burial depth of the blade foot; the driving depth of the steel sheet piles is the height difference between the lower end of the steel sheet pile and the lower end of the blade foot.

[0022] According to a method for identifying and controlling the risk of sand gushing due to subsidence of a submerged foundation provided in the present application, the driving depth of the steel sheet piles is adjusted based on the actual burial depth of the blade foot and the critical burial depth of the blade foot: the driving depth of the steel sheet piles is the difference between the product of the fourth multiple and the critical burial depth of the blade foot and the actual burial depth of the blade foot; the fourth multiple is not less than the third multiple.

[0023] According to a method for identifying and controlling the risk of subsidence and sand gushing of a submerged foundation provided in the present application, the fourth multiple is equal to the third multiple.

[0024] According to a method for identifying and controlling the risk of sand gushing during sinking of a submerged foundation provided in the present application, the method for inserting and driving steel sheet piles includes: when producing the submerged foundation, arranging a reserved groove section on the submerged foundation, the reserved groove section vertically penetrating the submerged foundation; the steel sheet piles pass through the reserved groove section from top to bottom and are inserted into the soil layer below the blade foot, and during the vibration and sinking process of the steel sheet piles, the soil layer is flushed based on the water jets on the steel sheet piles, so that the driving depth of the steel sheet piles reaches the required requirement.

[0025] According to a method for identifying and controlling the risk of sand gushing due to subsidence of a submerged foundation provided in the present application, during the vibration sinking process of the steel sheet piles, the soil layer is flushed based on the water jets on the steel sheet piles: the soil layer below the steel sheet piles is flushed based on the end water jets at the lower end of the steel sheet piles, and the soil layer inside the blade foot at the same elevation is flushed based on the horizontal water jets on the steel sheet piles that are flush with the lower end of the blade foot.

[0026] According to a method for identifying and controlling the risk of sand gushing from sinking of a submerged foundation provided in the present application, after the submerged foundation sinks into place, the inner wall of the reserved groove section is flushed and cleaned to complete the pouring of concrete into the reserved groove section.

[0027] The advantages of the present application are as follows: 1. The present application provides a method for identifying and controlling the risk of sand inrush during the sinking of a sunken foundation, which can monitor the condition of the sunken foundation in real time during the sinking process of the sunken foundation, determine whether there is a risk of sand inrush, and promptly handle the sunken foundation when there is a risk of sand inrush, thereby eliminating the problem of sand inrush and improving the stability and safety of the entire sunken foundation construction. Moreover, all operations of the method of the present application are based on rigorous calculations and have sufficient theoretical basis, thus realizing quantitative identification and early warning of sand inrush risks.

[0028] 2. This application constructs a calculation formula for the critical burial depth of the blade foot. The calculation formula of this application is calculated based on the internal and external water level elevations of the submerged foundation and the internal soil characteristics of the submerged foundation. The calculation formula constructed in this application can accurately obtain the current critical burial depth of the blade foot, which is convenient for subsequent judgment of whether there is a risk of sand inrush;

[0029] 3. The method for judging the risk of sand inrush in this application is very simple. By comparing the critical burial depth of the blade foot and the actual burial depth of the blade foot, it is possible to judge whether there is a risk of sand inrush. The method is simple, the warning of sand inrush risk is timely, and the operation is convenient;

[0030] 4. This application adopts different early warning prompts for different sand inrush risks. Through different early warning prompts, it is convenient for construction personnel to understand the current risk level of sand inrush of sunken foundation and facilitate subsequent operations of construction personnel;

[0031] 5. The method for determining the driving depth of the steel sheet pile in this application is very simple. The driving depth is completely determined based on the actual burial depth of the blade foot and the critical burial depth of the blade foot. The construction of the steel sheet pile has good data theory support, and the driving construction is more scientific and reasonable;

[0032] 6. This application calculates the driving depth of the steel sheet pile by the actual burial depth of the blade foot and the critical burial depth of the blade foot. The calculation method is simple, which can solve the sand gushing problem to the greatest extent and reduce the construction difficulty to the greatest extent;

[0033] 7. This application determines the fourth multiple, and determines that the driving depth of the steel sheet pile is the difference between the critical burial depth of the blade foot of the third multiple and the actual burial depth of the blade foot, which is equivalent to the steel sheet pile extending the length of the blade foot, reaching the depth that can solve the risk of sand inrush to the greatest extent, and the operation is extremely convenient;

[0034] 8. The application is very simple for the construction of steel sheet piles. The end resistance of the sunken foundation is weakened by high-pressure water jetting, which controls the sand inrush and ensures the rapid sinking of the sunken foundation.

[0035] 9. This application constructs a horizontal water jet on the steel sheet pile, through which the mud and sand at the bottom of the blade foot can be washed away, further reducing the risk of sand gushing;

[0036] 10. After the steel sheet piles are driven in, the present application forms a concrete structure at the bottom of the blade foot by pulling out the steel sheet piles and pouring concrete into the reserved groove section, which can effectively solve the sand gushing problem.

[0037] The method for identifying and controlling the risk of sand gushing during the sinking of a submerged foundation disclosed in the present application can calculate, analyze and evaluate the risk of sand gushing during the sinking of a submerged foundation, provide graded early warning for the risk of sand gushing, actively increase the limited embedding depth of the well wall blade foot before the risk of sand gushing reaches the limit value, and effectively remove the end resistance, thereby achieving effective control of the risk of sand gushing during the sinking construction of the submerged foundation.

[0038] The present application constructs a new type of sunken foundation structure, which can calculate the critical burial depth of the blade foot considering the influence of the head difference inside and outside the sunken foundation, thereby realizing the quantitative identification and early warning of the sand gushing risk; by driving steel sheet piles into the sunken foundation, the burial depth of the blade foot is increased, thereby effectively controlling the sand gushing risk of the sunken foundation; it can be applied to many engineering scenarios such as caissons, cofferdams, and pipe piles for soil excavation and sinking. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 : A top view of the sunken foundation of the present application;

[0040] Figure 2 :This application Figure 1 AA view;

[0041] Among them: 1—sunken foundation; 2—reserved trench section; 3—steel sheet piles; 4—end water jet; 5—horizontal water jet. DETAILED DESCRIPTION

[0042] The embodiments of the present invention are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0043] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0044] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] The present application relates to a method for identifying and controlling the risk of sand inrush during the sinking of a submerged foundation, which is used to identify and warn of the risk of sand inrush during the sinking process of the submerged foundation, and to perform operations based on the risk of sand inrush, thereby solving the problem of sand inrush risk by extending the buried depth of the blade foot of the submerged foundation. The sand inrush risk and control method of the present application can calculate the critical buried depth of the blade foot considering the influence of the head difference inside and outside the submerged foundation, thereby achieving quantitative identification and early warning of the risk of sand inrush; by driving steel sheet piles into the submerged foundation, the buried depth of the blade foot is increased, thereby effectively controlling the risk of sand inrush in the submerged foundation; and can be applied to many engineering scenarios such as caissons, cofferdams, and pipe piles for soil excavation and sinking.

[0047] Specifically, Figures 1-2 As shown, it is a schematic diagram of the structure of the sunken foundation 1 of the present application. The sunken foundation 1 of the present application is a square cofferdam structure, and is not limited to the square cofferdam structure in practical application. Figure 1Take the square cofferdam as an example. The sunken foundation 1 of the present application is a cofferdam structure surrounded by four groups of side walls, with a pointed blade foot structure at the lower end. A reserved slot section 2 is reserved on the sunken foundation 1. The reserved slot section 2 is a slot hole that vertically penetrates the sunken foundation 1. The reserved slot section 2 is convenient for the subsequent insertion of steel sheet piles 3. Multiple reserved slot sections 2 are arranged at intervals, and the subsequent steel sheet piles 3 pass through the reserved slot section 2 and are vibrated and sunk into the soil layer below the blade foot.

[0048] During actual construction, follow the steps below:

[0049] S1. During the sinking process of the submerged foundation 1, the critical burial depth of the blade foot is calculated based on the internal and external water level elevations of the submerged foundation 1 and the internal soil characteristics of the submerged foundation 1;

[0050] Real-time calculation of the critical burial depth of the blade foot facilitates subsequent judgment of the current burial depth of the blade foot and determines whether there is a risk of sand inrush caused by insufficient burial depth of the blade foot;

[0051] The critical burial depth of the blade foot is calculated based on the water level elevation inside and outside the sunken foundation 1 and the internal soil characteristics. Because the sand inrush risk is most related to the water level elevation inside and outside the sunken foundation 1 and the internal soil characteristics, the critical burial depth of the blade foot calculated based on these factors is the most effective in evaluating the sand inrush risk.

[0052] S2. Based on the actual burial depth of the blade foot and the critical burial depth of the blade foot, identify whether there is a risk of sand inrush;

[0053] The critical burial depth of the blade foot refers to the burial depth at which there is a risk of sand inrush when the burial depth of the blade foot is less than the critical burial depth of the blade foot. The actual burial depth of the blade foot refers to the height difference between the lower end of the blade foot and the elevation of the soil layer inside the sunken foundation 1. By comparing the critical burial depth of the blade foot with the actual burial depth of the blade foot, it can be determined whether there is a risk of sand inrush at present.

[0054] S3. When the risk of sand gushing is identified, steel sheet piles 3 are inserted into the sunken foundation 1 to control the occurrence of sand gushing;

[0055] Step S1 and step S2 are methods for identifying sand gushing risks, and step S3 is a method for controlling sand gushing risks. The present application achieves the effect of controlling sand gushing risks by inserting steel sheet piles 3 into the sunken foundation 1 and extending the burial depth of the blade foot.

[0056] In some embodiments of the present application, this embodiment optimizes the above-mentioned step S1. Specifically, the method for calculating the critical burial depth of the blade foot based on the internal and external water level elevations of the submerged foundation 1 and the internal soil characteristics of the submerged foundation 1 is:

[0057] Calculate the critical burial depth of the blade foot according to the following formula:

[0058]

[0059] Where: D2-critical embedding thickness of inner edge of sunken foundation 1 (m);

[0060] γ m1 -Heavyness of soil above the bottom of the outer blade of sunken foundation 1 (kN / m 3 ), and get it by looking up the table;

[0061] γ m2 -Heavyness of soil above the bottom of the inner blade of sunken foundation 1 (kN / m 3 ), and get it by looking up the table; γ w - Weight of water (kN / m 3 ), and get it by looking up the table;

[0062] Δh-water head difference between the inside and outside of the submerged foundation 1 (m), obtained by measurement;

[0063] h-the depth of sunken foundation 1 into the soil (m), obtained by measurement;

[0064] N c 、N q - Bearing capacity coefficient, obtained by looking up the table;

[0065] c-soil cohesion (kPa), obtained by looking up the table;

[0066] -Internal friction angle (°), obtained by looking up the table.

[0067] The critical burial depth of the blade foot can be obtained in real time through the above method.

[0068] In other embodiments of the present application, this embodiment optimizes the method of identifying whether there is a risk of sand gushing based on the current actual burial depth of the blade foot and the critical burial depth of the blade foot in the above-mentioned step S2. Specifically, when the actual burial depth of the blade foot is not greater than a set multiple of the critical burial depth of the blade foot, it is judged that the current sunken foundation 1 has a risk of sand gushing; the set multiple is greater than 1.

[0069] The critical burial depth of the blade foot is the critical value between no sand inrush risk and the existence of sand inrush risk. Therefore, as long as the actual burial depth of the blade foot is less than the critical burial depth of the blade foot, there is a risk of sand inrush. However, in actual application, considering some other factors, in the process of comparing the critical burial depth of the blade foot and the actual burial depth of the blade foot, the actual burial depth of the blade foot can be compared with the critical burial depth of the blade foot that is a multiple of 1, so that a margin can be left.

[0070] More specifically, when the actual burial depth of the blade foot is not greater than the product of the first multiple and the critical burial depth of the blade foot, a red warning of sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the first multiple and the critical burial depth of the blade foot and is not greater than the product of the second multiple and the critical burial depth of the blade foot, an orange warning of sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the second multiple and the critical burial depth of the blade foot and is not greater than the product of the third multiple and the critical burial depth of the blade foot, a yellow warning of sand gushing is issued; the third multiple is greater than the second multiple, greater than the first multiple, and greater than or equal to 1. The first multiple is 1, the second multiple is 1.1, and the third multiple is 1.2. In actual application, it is not limited to these values, and appropriate values ​​can be selected for operation according to actual needs.

[0071] By setting different warning levels, operators can be prompted to adopt control strategies according to different warning levels, and different degrees of operations can be performed according to different warning levels.

[0072] In a further embodiment of the present application, the present embodiment optimizes the above step S3. Specifically, the method of inserting the steel sheet pile 3 into the sunken foundation 1 in the present embodiment is as follows: Figure 2 As shown, based on the reserved groove section 2 vertically penetrating the sunken foundation 1 along the upper edge of the sunken foundation 1, the steel sheet pile 3 is inserted into the sunken foundation 1, and the driving depth of the steel sheet pile 3 is adjusted based on the actual buried depth of the blade foot and the critical buried depth of the blade foot. Then, the steel sheet pile 3 is driven in according to the set driving depth. After the steel sheet pile 3 is vibrated and sunk to the set driving depth, the steel sheet pile 3 is pulled out and then concrete is poured into the reserved groove section 2, which is equivalent to forming a plurality of spaced concrete leg structures under the blade foot of the sunken foundation 1, extending the buried depth of the blade foot of the sunken foundation 1. In the process of pulling out the steel sheet pile 3, the reserved groove section 2 needs to be flushed and cleaned to facilitate the subsequent concrete pouring.

[0073] Specifically, the driving depth of the steel sheet pile 3 is adjusted based on the actual buried depth of the blade foot and the critical buried depth of the blade foot: the driving depth of the steel sheet pile 3 is the difference between the product of the fourth multiple and the critical buried depth of the blade foot and the actual buried depth of the blade foot, and the driving depth of the steel sheet pile 3 is the height difference between the lower end of the steel sheet pile 3 and the lower end of the blade foot; the fourth multiple is not less than the third multiple, the fourth multiple is equal to the third multiple, and can be taken as 1.2.

[0074] In addition, in order to facilitate the vibration and sinking construction of the steel sheet pile 3, the present embodiment is provided with an end water jetting port 4 at the lower end of the steel sheet pile 3. The end water jetting port 4 can flush the soil layer at the lower end of the steel sheet pile 3, and weaken the end resistance of the submerged foundation 1 by high-pressure water jetting, thereby ensuring the rapid sinking of the submerged foundation 1 while controlling the sand gushing.

[0075] During actual vibration sinking, when the submerged foundation 1 is produced, a reserved groove section 2 is arranged on the submerged foundation 1, and the reserved groove section 2 vertically penetrates the submerged foundation 1; the steel sheet pile 3 passes through the reserved groove section 2 from top to bottom and is inserted into the soil layer below the blade foot, and during the vibration sinking process of the steel sheet pile 3, the soil layer is flushed based on the water injection port on the steel sheet pile 3, so that the driving depth of the steel sheet pile 3 reaches the required requirement.

[0076] The end water jet port 4 is connected to the water pump above through a high-pressure water pipe. In addition, a horizontal water jet port 5 flush with the blade foot is included, and the soil layer inside the blade foot at the same elevation position is scoured through the horizontal water jet port 5 flush with the lower end of the blade foot on the steel sheet pile 3.

[0077] After the steel sheet piles 3 are inserted, the steel sheet piles 3 are pulled out and the reserved groove section 2 is flushed and cleaned using the high-pressure water pipe (i.e., the end water jet 4 and the horizontal water jet 5) on the steel sheet pile 3. After the flushing and cleaning is completed, concrete is poured into the reserved groove section 2.

[0078] During actual construction, when the submerged foundation 1 is produced, a reserved groove section 2 is arranged on the submerged foundation 1; during the sinking process of the submerged foundation 1, the critical burial depth of the blade foot is calculated according to the above formula based on the internal and external water level elevations of the submerged foundation 1 and the internal soil characteristics of the submerged foundation 1; the actual burial depth of the blade foot is obtained in real time, and when the actual burial depth of the blade foot is not greater than the product of the first multiple and the critical burial depth of the blade foot, a red warning for sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the first multiple and the critical burial depth of the blade foot and is not greater than the product of the second multiple and the critical burial depth of the blade foot, an orange warning for sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the second multiple and the critical burial depth of the blade foot and is not greater than the product of the third multiple and the critical burial depth of the blade foot, an alarm is issued. Yellow warning for sand gushing; as long as the warning for sand gushing is issued, the steel sheet pile 3 is inserted from top to bottom through the reserved groove section 2 into the soil layer below the blade foot, and the steel sheet pile 3 is vibrated and sunk according to the difference between the product of the fourth multiple of the steel sheet pile 3 and the critical burial depth of the blade foot and the actual burial depth of the blade foot. During the construction process, the end water jet 4 at the lower end of the steel sheet pile 3 is used to flush the underlying soil layer. After the steel sheet pile 3 is vibrated and sunk to the calculated driving depth, the horizontal water jet 5 on the steel sheet pile 3 is used to flush the inner soil. The steel sheet pile 3 is pulled out and the reserved groove section 2 is flushed and cleaned with the high-pressure water pipe on the steel sheet pile 3. After the flushing and cleaning are completed, concrete is poured into the reserved groove section 2. The construction of sand gushing risk control for the sunken foundation 1 is completed.

[0079] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. The present invention may be subject to various changes and improvements without departing from the spirit and scope of the present invention. These changes and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation, characterized by: include, During the sinking process of the sunken foundation, the critical burial depth of the blade foot is calculated based on the internal and external water level elevations of the sunken foundation and the soil characteristics inside the sunken foundation. Based on the actual burial depth of the blade foot and the critical burial depth of the blade foot, identify whether there is a risk of sand inrush; When the risk of sand inrush is identified, steel sheet piles are inserted into the sunken foundation to control the sand inrush.

2. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 1, characterized in that: The method for calculating the critical burial depth of the blade foot comprises: calculating the critical burial depth of the blade foot according to the following formula: Where: D2-critical embedding thickness of the inner edge of the sunken foundation (m); γ m1 - Weight of soil above the bottom of the outer blade of the sunken foundation (kN / m 3 ); γ m2 - Weight of soil above the bottom of the inner blade of the sunken foundation (kN / m 3 ); γ w - Weight of water (kN / m 3 ); Δh-water head difference between inside and outside of the submerged foundation (m); h-sunken foundation depth (m); N c 、N q - bearing capacity coefficient; c-cohesion of soil (kPa); - Angle of internal friction (°).

3. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 1, characterized in that: The method for identifying whether there is a risk of sand gushing includes: when the actual burial depth of the blade foot is not greater than a set multiple of the critical burial depth of the blade foot, judging that there is a risk of sand gushing in the current sunken foundation; the set multiple is greater than 1.

4. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 3, characterized in that: When the actual burial depth of the blade foot is not greater than the product of the first multiple and the critical burial depth of the blade foot, a red warning for sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the first multiple and the critical burial depth of the blade foot and is not greater than the product of the second multiple and the critical burial depth of the blade foot, an orange warning for sand gushing is issued; when the actual burial depth of the blade foot is greater than the product of the second multiple and the critical burial depth of the blade foot and is not greater than the product of the third multiple and the critical burial depth of the blade foot, a yellow warning for sand gushing is issued; the third multiple is greater than the second multiple, greater than the first multiple, and greater than or equal to 1.

5. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 4, characterized in that: The method for inserting steel sheet piles into a submerged foundation comprises: inserting steel sheet piles into the submerged foundation based on a reserved groove section vertically penetrating the submerged foundation on the lower side of the submerged foundation, and adjusting the driving depth of the steel sheet piles based on the actual burial depth of the blade foot and the critical burial depth of the blade foot; the driving depth of the steel sheet piles is the height difference between the lower end of the steel sheet pile and the lower end of the blade foot.

6. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 5, characterized in that: The driving depth of the steel sheet pile is adjusted based on the actual burial depth of the blade foot and the critical burial depth of the blade foot: the driving depth of the steel sheet pile is the difference between the product of the fourth multiple and the critical burial depth of the blade foot and the actual burial depth of the blade foot; the fourth multiple is not less than the third multiple.

7. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 6, characterized in that: The fourth multiple is equal to the third multiple.

8. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 5, characterized in that: The method for inserting and driving steel sheet piles comprises: during the production of the sunken foundation, a reserved groove section is arranged on the sunken foundation, and the reserved groove section vertically penetrates the sunken foundation; the steel sheet piles pass through the reserved groove section from top to bottom and are inserted into the soil layer below the blade foot, and during the vibration sinking process of the steel sheet piles, the soil layer is flushed based on the water jets on the steel sheet piles, so that the driving depth of the steel sheet piles reaches the required requirement.

9. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 8, characterized in that: During the vibration sinking process of the steel sheet piles, the soil layer is scoured based on the water jets on the steel sheet piles: the soil layer below the steel sheet piles is scoured based on the end water jets at the lower end of the steel sheet piles, and the soil layer inside the blade foot at the same elevation is scoured based on the horizontal water jets on the steel sheet piles that are flush with the lower end of the blade foot.

10. A method for identifying and controlling the risk of subsidence and sand inrush of a submerged foundation as claimed in claim 9, characterized in that: After the sunken foundation sinks into place, the inner wall of the reserved groove section is flushed and cleaned to complete the pouring of concrete into the reserved groove section.

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