A method for determining the type of shield mud film in a sandy stratum slurry

Abstract

The present application relates to a kind of sandy formation slurry shield mud film type judging method, comprising the following steps: obtaining stratum soil sample and mud material sample;According to the obtained stratum soil sample, obtain the porosity and permeability coefficient of stratum soil sample, according to the obtained mud material sample, obtain the control particle size of mud material;According to control particle size, obtain particle size distribution adjustment coefficient;According to particle size distribution adjustment coefficient, the porosity of stratum soil sample, permeability coefficient and control particle size, obtain evaluation parameter;According to evaluation parameter, obtain the type of mud film.The method of the present application is simple and practical, can use index to quantify the state of mud film, provides basis for the control method and maintenance excavation face stability of mud.

Description

Technical Field

[0001] This invention relates to the field of slurry shield tunneling technology, specifically to a method for determining the mud film type in slurry shield tunneling in sandy strata. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Slurry shield tunneling machines can rapidly and evenly transmit slurry pressure in complex underwater construction environments, and offer high precision in excavation face control. They are increasingly being used in long-distance, deep-buried, high-water-pressure, and large-diameter underwater tunnel projects crossing rivers and seas. During tunnel excavation, a layer of impermeable or slightly permeable mud film is generated ahead of the excavation face through slurry infiltration, establishing slurry pressure and achieving water-soil pressure balance to maintain the stability of the excavation face.

[0004] To achieve suitable mud film support during construction, scholars have conducted extensive research on mud slurry preparation and geological suitability, as well as the permeability and stability of the mud film. However, visualization of the mud chamber and excavation face is difficult to achieve during slurry shield tunnel excavation. Current evaluation methods for slurry shield tunnel mud films mainly rely on: 1) deriving the ultimate support force of the excavation face through theoretical models to evaluate the quality of the mud film; 2) evaluating the filtration loss of the mud film in mud permeability tests; and 3) evaluating the state and quality of the mud film through the pressure conversion rate of the mud slurry. These evaluation methods cannot consider the complexity of sandy strata, cannot use quantitative standards to determine the compatibility between the mud slurry and the strata, and cannot provide guidance for the control of slurry in slurry shield tunnels, thus having low engineering practicality.

[0005] This indicates that there is currently insufficient research on the formation state and quality assessment methods for mud films in slurry shield tunneling in sandy strata. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a simple and practical method for determining the mud film type in slurry shield tunneling in sandy strata. This method can quantify the state of the mud film using indicators, providing a basis for mud control methods and maintaining the stability of the excavation face. It can also provide real-time guidance on the on-site construction status, ensuring construction safety.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] An embodiment of the present invention provides a method for determining the mud film type of a slurry shield tunneling machine in sandy strata, comprising the following steps:

[0009] Obtain soil and mud material samples from the formation;

[0010] The porosity and permeability coefficient of the obtained soil samples are obtained, and the control particle size of the mud material is obtained based on the obtained mud material samples.

[0011] The particle size distribution adjustment coefficient is obtained based on the controlled particle size.

[0012] Evaluation parameters are obtained based on the particle size distribution adjustment factor, the porosity and permeability coefficient of the soil sample, and the control particle size.

[0013] The type of mud film is determined based on the evaluation parameters.

[0014] Optionally, the porosity of the soil sample is obtained using the ring cutter method.

[0015] Optionally, when using the ring cutter method to obtain the porosity of the formation soil sample, multiple ring cutter samples are obtained and the corresponding porosity is calculated. The average value of the multiple porosities is taken as the porosity of the formation soil sample.

[0016] Optionally, the permeability coefficient of the soil sample is obtained by indoor permeability tests with constant head or variable head.

[0017] Optionally, when conducting indoor permeability tests with constant or variable head, multiple test soil samples are obtained for testing, and the average permeability coefficient of the multiple soil samples is taken as the permeability coefficient of the formation soil sample.

[0018] Optionally, the controlled particle size of the mud material includes a first particle size, a second particle size, a third particle size, and a fourth particle size, wherein, in the mud material, the mass of particles smaller than the first particle size accounts for 10% of the total mass, the mass of particles smaller than the second particle size accounts for 30% of the total mass, the mass of particles smaller than the third particle size accounts for 60% of the total mass, and the mass of particles smaller than the fourth particle size accounts for 85% of the total mass.

[0019] Optionally, the controlled particle size of the mud material can be obtained by laser particle size analyzer or sieving method.

[0020] Optionally, when using a laser particle size analyzer, the corresponding control particle size can be directly read from the analysis results obtained by the laser particle size analyzer or calculated by interpolation.

[0021] Optionally, the non-uniformity coefficient and curvature coefficient of the mud are obtained based on the controlled particle size of the mud material, and the particle size distribution adjustment coefficient is obtained based on the non-uniformity coefficient and curvature coefficient.

[0022] Optionally, when the evaluation parameter is not less than the first set value, the mud film is of the mud skin type; when the evaluation parameter is less than the first set value but not less than the second set value, the mud film is of the mud skin and permeable zone combination type; when the evaluation parameter is less than the second set value, the mud film is of the permeable zone type.

[0023] Furthermore, the first setting value is 1.0, and the second setting value is 0.571.

[0024] The beneficial effects of this invention are as follows:

[0025] 1. The judgment method of the present invention obtains evaluation parameters based on the porosity and permeability coefficient of the soil sample, the particle size distribution adjustment coefficient of the mud, and the control particle size. The mud film type is judged based on the evaluation parameters. It not only considers the diverse pore distribution and permeability characteristics of strata with different degrees of sandification, but also considers the particle size relativity between sandified strata particles and mud particles used. For complex strata with different degrees of sandification, it can accurately judge the compatibility between mud and strata through quantitative standards, and can provide guidance for the control of mud in slurry shield tunneling. It has high engineering practicality.

[0026] 2. The judgment method of the present invention can determine the type of mud film formed by mud slurry penetration at the excavation face of slurry shield tunneling through indoor permeation tests and parameter calculation analysis. The method is simple and practical, and can quantify the state of the mud film with indicators. In addition, it can predict the pressure transmission path of the excavation face and the stability of the mud film support. It provides guidance and suggestions for mud slurry regulation and excavation face stability control of slurry shield tunneling in sandy strata, and ensures construction safety. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0028] Figure 1 This is a schematic diagram of the method flow of Embodiment 1 of the present invention;

[0029] Figure 2 This is a schematic diagram of the indoor permeability test under constant head in Embodiment 1 of the present invention;

[0030] Figure 3 This is a schematic diagram illustrating the mud film type determination in Embodiment 1 of the present invention;

[0031] Figure 4 This is a schematic diagram of the mud film obtained by determination in Embodiment 1 of the present invention;

[0032] Figure 5 This is a schematic diagram of the mud film + permeation zone combination mud membrane obtained by the determination in Embodiment 1 of the present invention;

[0033] Figure 6 This is a schematic diagram of the permeable zone mud membrane obtained by determination in Embodiment 1 of the present invention; Detailed Implementation

[0034] Example 1

[0035] This embodiment provides a method for determining the mud film type of slurry shield tunneling in sandy strata, such as... Figure 1 As shown, it includes the following steps:

[0036] Step 1: Obtain soil and mud samples from the formation;

[0037] Among them, the stratum soil sample refers to the sampling of the stratum soil at the excavation face of the slurry shield tunnel construction, and several samples are taken for backup. The mud material sample refers to the material used to prepare the mud at the slurry shield construction site, and several samples are taken for backup.

[0038] Step 2: Obtain the porosity and permeability coefficient of the obtained soil samples, and obtain the control particle size of the mud material based on the obtained mud material samples.

[0039] The porosity of the soil samples was obtained using existing ring sampler testing methods, specifically including the following steps:

[0040] Step 1): Obtain multiple ring cutter samples from the soil samples obtained in Step 1. In this embodiment, the number of ring cutter samples is 3-5.

[0041] Step 2): In the ring sampler sample, after saturating the soil sample inside the ring sampler with water, weigh the ring sampler and the saturated soil. The sum of their weights is the first weight W1.

[0042] Step 3): Dry the ring cutter sample in an oven at 105℃ until constant weight, let it stand for 12 hours, and then weigh the ring cutter sample W2.

[0043] Step 4): The volume of the ring cutter is V, and the porosity of the soil is n. n The calculation formula is

[0044]

[0045] After obtaining the porosity of 3-5 ring cutter soil samples, take the average value as the porosity n of the formation soil sample.

[0046] The permeability coefficient of the soil sample was obtained through existing constant head or variable head laboratory permeability tests. In this embodiment, the permeability coefficient of the soil sample was obtained using a constant head test. The specific method is as follows:

[0047] like Figure 2 As shown, a saturated soil sample (obtained by saturating the stratum soil sample with water) with cross-section A and length L is filled into a transparent cylinder. The water valve is opened, allowing water to flow from top to bottom through the soil sample and exit from the outlet. After the head difference Δh and seepage flow rate Q stabilize, the amount of water V flowing through the soil sample within a set time t is measured. The permeability coefficient k of the soil sample is then determined. n The calculation method is as follows:

[0048]

[0049] Multiple soil samples were taken for constant head indoor permeability tests. In this embodiment, 3-5 soil samples were taken for constant head indoor permeability tests, and the average value of the measurement results was taken as the permeability coefficient k of the stratum soil sample.

[0050] The controlled particle size of mud materials includes the first particle size d 10 Second particle size d 30 Third particle size d 60 and the fourth particle size d 85 .

[0051] Particles in the mud material with a diameter smaller than the first particle size d 10 The particle mass accounts for 10% of the total mass, and the particle size of the mud material particles is smaller than the second particle size d. 30 The particle mass accounts for 30% of the total mass, and the particle size of the mud material particles is smaller than the third particle size d. 60 The particle mass accounts for 60% of the total mass, and the particle size of the mud material particles is smaller than the fourth particle size d. 85 The particles account for 85% of the total mass. The fourth particle size d... 85 Let it be denoted as f.

[0052] In this embodiment, the control particle size of the mud material is obtained by particle analysis tests using an existing laser particle size analyzer or sieving method. Preferably, a laser particle size analyzer is used to perform particle analysis on the mud material. After obtaining the analysis results such as the particle size distribution curve and material analysis report, the corresponding control particle size is directly read or calculated by interpolation.

[0053] Step 3: Obtain the particle size distribution adjustment coefficient based on the controlled particle size.

[0054] The particle size adjustment factor i is obtained through the mud non-uniformity coefficient C. u and curvature coefficient C c The determination refers to the compensation and adjustment of mud particle size distribution during mud film formation. The non-uniformity coefficient C... u and curvature coefficient C c Controlled particle size d 10 d 30 d 60 According to the formula Sure.

[0055] The values ​​of the particle size distribution adjustment coefficient are shown in the table below:

[0056] Table 1: Values ​​of Particle Size Distribution Adjustment Coefficient

[0057] Inhomogeneity coefficient Cu curvature coefficient Cc Grading adjustment factor i Cu≤5.8 —— 0 —— Cc≤1 or Cc≥3 0 Cu>5.8 1 < Cc ≤ 1.48 or 2.41 ≤ Cc < 3 0.91 Cu>5.8 1.48 < Cc < 2.41 1.0

[0058] Inhomogeneity coefficient Cu When ≤5.8, the particle size distribution adjustment factor i=0; the curvature factor C c ≤1 or C c When ≥3, the particle size distribution adjustment factor i=0; the non-uniformity coefficient C u >5.8 and curvature coefficient 1 <C c ≤1.48 or 2.41≤C c When the coefficient of uniformity Cu is less than 3, the gradation adjustment coefficient i = 0.91; when the coefficient of non-uniformity Cu > 5.8 and the coefficient of curvature 1.48 < Cc < 2.41, the gradation adjustment coefficient i = 1.

[0059] Step 4: Obtain the evaluation parameter e based on the particle size distribution adjustment coefficient, the porosity and permeability coefficient of the soil sample, and the control particle size;

[0060] An evaluation parameter e is introduced to determine the type and quality of the mud film used in slurry shield tunneling in sandy strata, and the calculation is performed according to the following formula:

[0061]

[0062] Where f is the mud material d 85 The particle size is controlled by i, which is the particle size distribution adjustment coefficient, n is the porosity of the soil sample, and k is the permeability coefficient of the soil sample.

[0063] Step 5: As Figure 3 As shown, the type of mud film is obtained based on the evaluation parameters. Figure 3 In the diagram, the lower horizontal axis represents the equivalent particle size, which characterizes the particle size of the equivalent soil sample in the evaluation parameter e. The equivalent particle size is...

[0064] The details are shown in Table 2:

[0065] Table 2: Mud Film Type Judgment Table

[0066]

[0067] The larger the calculated evaluation parameter e, the higher the quality of the mud film formed. The method for determining the type of mud permeation film formation using the evaluation parameter e is as follows:

[0068] When the evaluation parameter is not less than the first set value, the mud film is of the mud skin type. When the evaluation parameter is less than the first set value but not less than the second set value, the mud film is of the mud skin and permeable zone combination type. When the evaluation parameter is less than the second set value, the mud film is of the permeable zone type.

[0069] Furthermore, the first setting value is 1.0, and the second setting value is 0.571.

[0070] Specifically, such as Figure 4As shown, when the evaluation parameter e ≥ 1.0, the mud film formed by mud penetration in sandy strata is of the mud cake type. The mud film can transfer all mud pressure to the excavation face soil in the form of approximately surface force, converting it into effective soil stress. The conversion efficiency is high, and the excavation face stability is strong. Figure 5 As shown, when the evaluation parameter is 0.571 ≤ e < 1.0, the mud infiltration in sandy formations forms a combination of mud cake and seepage zone. Part of the mud pressure is converted into surface force, and the remaining part maintains the stability of the excavation face in the form of seepage force. Figure 6 As shown, when the evaluation parameter e < 0.571, the mud infiltration film formation in sandy strata is of the infiltration zone type. In the pressure transmission, the mud pressure is maintained by the infiltration force to maintain the stability of the excavation face. Its pressure conversion efficiency is low and the excavation face stability is poor.

[0071] The method in this embodiment obtains evaluation parameters based on the porosity and permeability coefficient of the soil sample, the particle size distribution adjustment coefficient of the mud, and the control particle size. Based on these parameters, the mud film type is determined. This method considers not only the diverse pore distribution and permeability characteristics of strata with different degrees of sandification, but also the relative particle sizes of the sandy strata particles and the mud particles used. For complex strata with different degrees of sandification, it can accurately determine the compatibility between the mud and the strata through quantitative standards, providing guidance for mud control in slurry shield tunneling. It has high engineering practicality. Furthermore, the type of mud film formed by mud permeation at the slurry shield tunneling face can be analyzed through indoor permeability tests and parameter calculations. The method is simple and practical, quantifying the state of the mud film with indicators, and thus predicting the pressure transmission path at the excavation face and the stability of the mud film support. It provides guidance and suggestions for mud control and excavation face stability control in slurry shield tunneling in sandy strata, ensuring construction safety.

[0072] In a practical application of this embodiment:

[0073] The soil samples were from sandy strata excavated using a slurry shield tunneling machine. The S1 type soil had a particle size range of 0.25-0.5 mm, and the D... 10 (The particle size corresponding to a cumulative particle size distribution percentage of 10% in a soil sample is that of particles smaller than D in the soil) 10 The particle mass (accounting for 10% of the total mass) is 0.275 mm, D 60 (The particle size corresponding to a cumulative particle size distribution percentage of 60% in a soil sample is that which is smaller than D in the soil) 60 The particle size distribution (60% of the total mass) is 0.4 mm, and the soil particle uniformity coefficient C u The value is 1.45, and k is 6.5 × 10. -4 m / s, n is 0.42, the particle size range of S2 type soil is 1-2mm, D10 (the particle size corresponding to the cumulative particle size distribution percentage of the soil sample reaching 10%, i.e., the particle size in the soil is smaller than D) 10The particle size (10% of the total mass) is 1.1 mm, and D60 (the particle size corresponding to 60% of the cumulative particle size distribution of the soil sample, i.e., the particle size smaller than D in the soil) is 1.1 mm. 60 The particle size distribution (60% of the total mass) is 1.6 mm, and the soil particle uniformity coefficient C u The value is 1.45, and k is 9.1 × 10. -3 m / s, n is 0.43. All of the above parameters can be obtained through existing experimental methods.

[0074] The permeability coefficient of the soil samples was determined as follows: three samples of each of the S1 and S2 types of soil were taken, and the permeability coefficients measured under constant head permeability tests were averaged to obtain the permeability coefficient for each soil type. The porosity of the soil samples was determined as follows: three samples of each of the S1 and S2 types of soil were taken, and the porosity was measured using the ring cutter method. The average porosity was obtained to obtain the porosity for each soil type. Two types of test mud were used: SL1 type mud material had a bentonite content of 8.55%, a sand content of 34.92%, and a density of 1.1 g / m³. 3 Controlling particle size d 85 The thickness is 155 μm, and the coefficient of non-uniformity is C. u =6.5, curvature coefficient C c =2.12, particle size distribution adjustment factor is taken as 1.0. Particle size distribution adjustment factor is taken as 1.0. SL2 type mud material has a bentonite content of 6.32%, a sand content of 60.69%, and a density of 1.3 g / m³. 3 Controlling particle size d 85 The thickness is 187 μm, and the coefficient of non-uniformity is C. u =6.3 curvature coefficient C c =1.72, and the particle size distribution adjustment coefficient is taken as 1.0. The determination of the control particle size and particle size distribution adjustment coefficient of the mud material is as follows: particle size analysis is performed on SL1 and SL2 type mud materials using an LS13320 laser particle size analyzer to obtain particle size distribution curves and analysis reports, the control particle size is read, and the particle size distribution adjustment coefficient is determined by the particle non-uniformity coefficient and curvature coefficient.

[0075] In one implementation, when using SL1 type mud to form a permeable film in S1 type soil, the calculated evaluation parameters e = 2.67, e ≥ 1.0, determine that the generated mud film type is mud cake type. The mud film can transfer all mud pressure to the excavation face soil in the form of approximately surface force, converting it into effective soil stress, with high conversion efficiency and strong excavation face stability.

[0076] In one implementation, when using SL1 type mud to form a seepage film in S2 type soil, the calculated evaluation parameter e = 0.73, where 0.57 ≤ e < 1.0, indicates that the mud film type is a combination of mud cake and seepage zone. Part of the mud pressure is converted into surface force, and the remaining part maintains the stability of the excavation face in the form of seepage force.

[0077] In one implementation, when using SL1 type mud to form a permeable film in S2 type soil, the calculated evaluation parameter e1 = 0.73, 0.57 ≤ e < 1.0, indicates that the generated mud film type is a combination of mud cake and permeable zone. When using SL2 type mud to form a permeable film in S2 type soil, e2 = 0.89, 0.57 ≤ e < 1.0, also indicates that the generated mud film type is a combination of mud cake and permeable zone. Since e1 < e2, it can be concluded that the quality of the mud film formed by permeating S2 type soil using SL2 type mud is superior to that formed by permeating S2 type soil using SL1 type mud.

[0078] In one implementation, the criteria for determining the type of mud infiltration film formation are as follows: when the evaluation parameter e ≥ 1.0, the mud infiltration film formation in sandy formations is of the mud skin type; when the evaluation parameter 0.571 ≤ e < 1.0, the mud infiltration film formation in sandy formations is of the mud skin + infiltration zone combination type; when the evaluation parameter e < 0.571, the mud infiltration film formation in sandy formations is of the infiltration zone type.

[0079] In one implementation, the quality comparison of the same type of mud film is accomplished by comparing the evaluation parameter e, and the larger the evaluation parameter e is, the higher the quality of the mud film.

[0080] In one embodiment, when excavating a tunnel using a slurry shield tunneling machine, in order to obtain a higher quality mud film, the quality of the existing mud film can be evaluated and the mud slurry ratio optimized using the evaluation parameter e.

[0081] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the mud film type of a slurry shield tunneling machine in sandy strata, characterized in that, Includes the following steps: Obtain soil and mud material samples from the formation; The porosity and permeability coefficient of the obtained soil samples are obtained, and the control particle size of the mud material is obtained based on the obtained mud material samples. The controlled particle size of the mud material includes a first particle size, a second particle size, a third particle size, and a fourth particle size. Among the mud material, particles smaller than the first particle size account for 10% of the total mass, particles smaller than the second particle size account for 30% of the total mass, particles smaller than the third particle size account for 60% of the total mass, and particles smaller than the fourth particle size account for 85% of the total mass. The particle size distribution adjustment coefficient is obtained based on the controlled particle size. The non-uniformity coefficient and curvature coefficient of the mud are obtained based on the controlled particle size of the mud material, and the particle size distribution adjustment coefficient is obtained based on the non-uniformity coefficient and curvature coefficient. Evaluation parameters are obtained based on the particle size distribution adjustment factor, the porosity and permeability coefficient of the soil sample, and the control particle size. The type of mud film is determined based on the evaluation parameters.

2. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 1, characterized in that, The porosity of the soil samples was obtained using the ring cutter method.

3. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 2, characterized in that, When obtaining the porosity of a formation soil sample using the ring cutter method, multiple ring cutter samples are obtained and their corresponding porosities are calculated. The average value of the multiple porosities is taken as the porosity of the formation soil sample.

4. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 1, characterized in that, The permeability coefficient of the soil samples was obtained using indoor permeability tests with constant or variable head.

5. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 4, characterized in that, When conducting indoor permeability tests with constant or variable water head, multiple test soil samples are obtained for testing, and the average permeability coefficient of the multiple soil samples is taken as the permeability coefficient of the stratum soil sample.

6. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 1, characterized in that, The controlled particle size of the mud material is obtained by laser particle size analyzer or sieving method.

7. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 6, characterized in that, When using a laser particle size analyzer, the corresponding control particle size can be directly read from the analysis results obtained by the laser particle size analyzer or calculated by interpolation.

8. The method for determining the mud film type of a slurry shield tunneling machine in sandy strata as described in claim 1, characterized in that, When the evaluation parameter is not less than the first set value, the mud film is of the mud skin type; when the evaluation parameter is less than the first set value but not less than the second set value, the mud film is of the mud skin and permeable zone combination type; when the evaluation parameter is less than the second set value, the mud film is of the permeable zone type. Furthermore, the first setting value is 1.0, and the second setting value is 0.571.

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