Method for determining sudden mud of open of sinking well

Abstract

The present application relates to a kind of well sinking opening mud burst determination method. Whether the well sinking opening of pipe jacking construction will appear mud burst, mostly based on engineering experience determination, result is unreliable. The present application obtains the design parameter of well sinking opening, the specific gravity of soil body around well sinking, and the cohesion and internal friction angle of soil body;The gravity of unit width inside mud burst body, groundwater seepage force of unit width inside mud burst body, the pressure of top of unit width inside mud burst body, and the damage force when unit width inside mud burst appears are calculated;The resistance of top of unit width inside mud burst body, the resistance of bottom of unit width inside mud burst body, and the total resistance of unit width inside mud burst body are calculated;The damage force when unit width inside mud burst appears and the total resistance of unit width inside mud burst body are compared, and the determination result is obtained. The present application judges whether mud burst will appear by combining the damage force of mud burst and the resistance of mud burst, the principle is clear, the operability is strong, and more reliable result can be obtained.

Description

Technical Field

[0001] This invention relates to the field of pipe jacking construction technology, specifically to a method for determining mud outburst at the opening of a caisson. Background Technology

[0002] In pipe jacking construction, caissons are an essential structural element. They provide working space for pipe jacking and also support the surrounding soil to maintain its stability. Before jacking, equipment is often used to pre-open a pre-reserved opening at the bottom of the caisson. Once this opening is exposed, a free surface is created. If the opening depth or size is large, or the soil properties are poor, the soil at the opening is prone to collapse, causing mudslides, which can lead to serious disasters such as ground subsidence. To date, the determination of whether mudslides will occur at the opening is largely based on engineering experience, and there is no reliable method for assessment. Therefore, a method is needed to determine whether mudslides will occur after the opening is made, thus solving the current problem of not being able to determine whether mudslides will occur at the caisson opening. Summary of the Invention

[0003] The purpose of this invention is to provide a method for determining mud inrush at the opening of a caisson, so as to solve the unreliable problem of judging whether mud inrush exists at the opening of a caisson solely based on engineering experience.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for determining mud outburst at the opening of a caisson, the method comprising:

[0006] Obtain the design parameters for the caisson opening;

[0007] Obtain the unit weight of the soil surrounding the caisson, as well as the soil cohesion and internal friction angle;

[0008] Based on the design parameters, density, and internal friction angle, calculate the gravity of the mud-burrowing body per unit width, the groundwater seepage force of the mud-burrowing body per unit width, the downward pressure on the top of the mud-burrowing body per unit width, and the destructive force when the mud-burrowing body appears per unit width.

[0009] Based on the design parameters, cohesion, and internal friction angle, calculate the resistance of the top of the protruding mud body per unit width, the resistance of the bottom of the protruding mud body per unit width, and the total resistance of the protruding mud body per unit width.

[0010] The judgment result is obtained by comparing the destructive force when mudslides occur within a unit width with the total resistance of mudslides within a unit width.

[0011] Furthermore, the design parameters for the caisson opening include the upper edge burial depth H and the opening height D.

[0012] Furthermore, the unit weight of the soil surrounding the caisson, as well as the soil cohesion and internal friction angle, are obtained, including:

[0013] Drilling and sampling were carried out in the soil surrounding the caisson.

[0014] The density of the sample was tested using the ring cutter method. After the density was measured, it was multiplied by the gravitational acceleration to obtain the specific weight γ.

[0015] Rapid direct shear tests were conducted on the samples to measure the soil cohesion (c) and internal friction angle.

[0016] Furthermore, based on the design parameters, unit weight, and internal friction angle, the gravity of the mud protrusion per unit width is calculated, including:

[0017]

[0018] In the formula:

[0019] G is the weight of the mud mass per unit width;

[0020]

[0021] Furthermore, based on design parameters, unit weight, and internal friction angle, the groundwater seepage force per unit width of the mud mass is calculated, including:

[0022]

[0023] In the formula:

[0024] J represents the groundwater seepage force within a unit width of the protruding mud body;

[0025] i represents the hydraulic gradient;

[0026] γ w It is classified as severe groundwater.

[0027] Furthermore, based on the design parameters, unit weight, and internal friction angle, the downward pressure on the top of the protruding mud mass per unit width is calculated, including:

[0028] P=HγDcotα

[0029] In the formula:

[0030] P represents the downward pressure on the top of the protruding mud body per unit width.

[0031] Furthermore, the destructive force when mudslides occur per unit width is calculated, including:

[0032] T = (G + J + P)sinα

[0033] In the formula:

[0034] T represents the destructive force when mud bursts forth within a unit width.

[0035] Furthermore, based on the design parameters, cohesion, and internal friction angle, the resistance of the top of the protruding mud body per unit width, the resistance of the bottom of the protruding mud body per unit width, and the total resistance of the protruding mud body per unit width are calculated, including:

[0036] R1=cDcotα

[0037]

[0038] R = R1 + R2

[0039] In the formula:

[0040] R1 is the resistance of the top of the protruding mud body per unit width;

[0041] R2 is the resistance at the bottom of the protruding mud body per unit width;

[0042] R represents the total resistance of the mud mass per unit width.

[0043] Furthermore, by comparing the destructive force of mudslides occurring per unit width with the total resistance of the mudslide body per unit width, a judgment result is obtained, including:

[0044] If T>R, mudslides will occur at the opening of the caisson.

[0045] If T≤R, no mud will leak out at the caisson opening.

[0046] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0047] The method of this invention obtains the mud-bursting destructive force through the self-weight of the mud-bursting body, seepage force, and pressure of the overlying soil. At the same time, it obtains the mud-bursting resistance force through the cohesion between the top of the mud-bursting body and the overlying soil, and the shear strength between the bottom of the mud-bursting body and the underlying soil. Combining the two values ​​of mud-bursting destructive force and mud-bursting resistance force, it determines whether mud-bursting will occur. The principle is clear and the operation is strong. Compared with the method of judging by experience alone, it can obtain more reliable results and provides a more accurate quantitative method for determining whether mud-bursting will occur at the caisson opening. Attached Figure Description

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained from these drawings without creative effort.

[0049] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0050] To facilitate understanding of the present invention, a more complete description will be given below with reference to the accompanying drawings. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0051] In the description of this patent, it should be understood that all technical and scientific terms used have the same meaning as commonly understood by one of ordinary skill in the art to which this patent pertains. In case of any contradiction, the definitions in this specification shall prevail. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art, and the devices used in the embodiments are existing devices. The limitation of the means or devices shall not be construed as a limitation of this patent, and means or devices of the same type that solve the same technical problem are all within the protection scope of this patent.

[0052] In the description of this patent, it should be understood that the method involves multiple steps, which should not be interpreted as a limitation on the order of the steps. Technical solutions obtained by changing the order of steps when solving the same technical problem are also within the scope of protection of this patent.

[0053] During pipe jacking construction, if mudslides occur at the caisson opening, it can cause safety hazards, ground subsidence, and other disasters, leading to project delays and increased costs. Once the caisson opening is opened, the soil in front loses its support, and the mudslide, under its own weight, seepage force, and overlying soil pressure, emerges at a certain angle. The self-weight, seepage force, and overlying soil pressure provide the destructive force for the mudslide. The cohesion between the top of the mudslide and the overlying soil provides a force to resist the mudslide, while the shear strength between the bottom of the mudslide and the underlying soil provides another force to resist the mudslide. These two forces provide the resistance to the mudslide. The relative magnitudes of the destructive force and the resistance determine whether mudslides occur. Based on this principle, this invention provides a method for determining mudslides at caisson openings, such as... Figure 1 Specifically, it includes the following steps:

[0054] S1: Obtain the design parameters for the caisson opening.

[0055] The design parameters for the caisson opening include the burial depth H at the upper edge and the opening height D.

[0056] S2: Obtain the unit weight of the soil surrounding the caisson, as well as the soil cohesion and internal friction angle, including:

[0057] S201: Drilling and sampling are carried out in the soil surrounding the caisson;

[0058] S202: The density of the sample is tested using the ring cutter method. After the density is measured, it is multiplied by the gravitational acceleration to obtain the specific weight γ.

[0059] S203: Conduct a rapid direct shear test on the sample to determine the soil cohesion (c) and internal friction angle.

[0060] S3: Based on design parameters, unit weight, and internal friction angle, calculate the gravity of the mud-burrowing mass per unit width, the groundwater seepage force of the mud-burrowing mass per unit width, and the downward pressure on the top of the mud-burrowing mass per unit width. Also calculate the destructive force when the mud-burrowing mass occurs per unit width, specifically including:

[0061] S301: Calculate the weight of the mud protrusion per unit width based on design parameters, unit weight, and internal friction angle.

[0062]

[0063] In the formula:

[0064] G is the weight of the mud mass per unit width;

[0065]

[0066] S302: Calculate the groundwater seepage force per unit width of the mud protrusion based on design parameters, unit weight, and internal friction angle.

[0067]

[0068] In the formula:

[0069] J represents the groundwater seepage force within a unit width of the protruding mud body;

[0070] i represents the hydraulic gradient, which is set to 1.0.

[0071] γ w The specific gravity of groundwater, γ w Take 10kN / m 3 .

[0072] S303: Calculate the downward pressure on the top of the protruding mud body per unit width based on design parameters, unit weight, and internal friction angle.

[0073] P=HγDcotα

[0074] In the formula:

[0075] P represents the downward pressure on the top of the protruding mud body per unit width.

[0076] S304: Calculate the destructive force when mudslides occur per unit width:

[0077] T = (G + J + P)sinα

[0078] In the formula:

[0079] T represents the destructive force when mud bursts forth within a unit width.

[0080] S4: Based on the design parameters, cohesion, and internal friction angle, calculate the resistance of the top of the protruding mud body per unit width, the resistance of the bottom of the protruding mud body per unit width, and the total resistance of the protruding mud body per unit width, including:

[0081] R1=cDcotα

[0082]

[0083] R = R1 + R2

[0084] In the formula:

[0085] R1 is the resistance of the top of the protruding mud body per unit width;

[0086] R2 is the resistance at the bottom of the protruding mud body per unit width;

[0087] R represents the total resistance of the mud mass per unit width.

[0088] S5: Compare the destructive force when mudslides occur within a unit width with the total resistance of mudslides within a unit width to obtain the judgment result.

[0089] If T>R, mudslides will occur at the opening of the caisson.

[0090] If T≤R, no mud will leak out at the caisson opening.

[0091] Example:

[0092] Using the method of this invention, a quantitative determination of whether mudslides have occurred is made, taking a specific engineering practice as an example.

[0093] In a certain project, a water conveyance tunnel was constructed using the pipe jacking method when passing through weak surrounding rock. Caissons were built at both ends of the pipe jacking. To determine whether a mudslide disaster would occur after the caisson opening, the method of this invention was used. According to the caisson design, the burial depth H of the upper edge of the caisson opening was determined to be 18.0m, and the opening height D was determined to be 5.0m. Sampling was conducted in the soil surrounding the caisson, and the samples were transported back to the laboratory for density testing using the ring cutter method. After measuring the density, multiplying it by the acceleration due to gravity, the unit weight γ of the soil surrounding the caisson was obtained as 19.2 kN / m³. 3 Using soil samples obtained from the aforementioned drilling rig, a rapid direct shear test was conducted in the laboratory. The test results showed that the soil cohesion c was 25 kPa and the internal friction angle was... The angle is 18°. Further analysis determined the gravity G of the mud-burrowing mass per unit width to be 174.4 kN / m, the groundwater seepage force J of the mud-burrowing mass per unit width to be 90.8 kN / m, the downward pressure P at the top of the mud-burrowing mass per unit width to be 1255.5 kN / m, and the destructive force T at the appearance of the mud-burrowing mass per unit width to be 1230.3 kN / m. The resistance R1 at the top of the mud-burrowing mass per unit width to be 90.8 kN / m, the resistance R2 at the bottom of the mud-burrowing mass per unit width to be 944.9 kN / m, and the total resistance R of the mud-burrowing mass per unit width to be 1035.7 kN / m. Since T > R, mud-burrowing will occur after the caisson opening is opened. Therefore, the soil behind the caisson opening should be pre-reinforced to increase its strength and prevent mud-burrowing.

[0094] This invention provides a quantitative method for determining whether mudslides will occur at the caisson wellhead, proposing to use the relative relationship between the destructive force and resistance of the mudslide as the criterion. Furthermore, it calculates two sets of data based on the actual design parameters of the wellhead and the characteristics of the soil around it, making the results more targeted and reliable, eliminating reliance on engineering experience to determine whether mudslides will occur at the caisson wellhead. By predicting the possibility of mudslides at the caisson wellhead in advance, necessary measures can be taken to effectively prevent mudslides, improve project safety, and effectively ensure the construction period.

[0095] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A method for determining mud outburst at the opening of a caisson, characterized in that: The method includes: Obtain the design parameters for the caisson opening, including the burial depth of the upper edge. Opening height ; Obtain the unit weight of the soil surrounding the caisson and the cohesion of the soil and internal friction angle ; Based on design parameters and density and internal friction angle Calculate the gravity of the mud mass per unit width. Groundwater seepage force within a unit width of the mud mass Downward pressure on the top of the mud mass per unit width Calculate the destructive force when mudslides occur within a unit width. ,Right now: ； ； ； ； In the formula: ； Hydraulic gradient; The specific gravity of the groundwater is 100%. Based on design parameters and cohesion and internal friction angle Calculate the resistance of the top of the mud mass within a unit width. Resistance of the bottom of the mud body within a unit width And calculate the total resistance of the mud mass per unit width. ,Right now: ； ； ； Compare the destructive force when mudslides occur per unit width and the total resistance of the mud body within a unit width The judgment result is obtained.

2. The method according to claim 1, characterized in that: Obtain the unit weight of the soil surrounding the caisson and the cohesion of the soil and internal friction angle ,include: Drilling and sampling were carried out in the soil surrounding the caisson. The density of the sample was measured using the ring cutter method. After measuring the density, it was multiplied by the acceleration due to gravity to obtain the specific weight. ; Rapid direct shear tests were conducted on the samples to determine the cohesion of the soil. and internal friction angle .

3. The method according to claim 1 or 2, characterized in that: Compare the destructive force when mudslides occur per unit width and the total resistance of the mud body within a unit width The judgment result is obtained, including: like Mud may burst through the opening of the caisson; like No mud will leak out at the opening of the caisson.

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