Slurry making method for slurry shield and shield slurry

Abstract

The invention provides a slurry making method for a slurry shield and shield slurry, raw materials of the slurry making method comprise bentonite, a water reducing agent and an additive, the slurry making method comprises the following steps: mixing a water reducing agent mother solution with the bentonite in a stirring state to obtain a premix, keeping stirring, and adding the additive into the premix to obtain the shield slurry. And mixing the premix with an additive to obtain the shield slurry. According to the slurry making method provided by the invention, by designing the specific adding sequence of the base material and the additive, the slurry making time is short, the material consumption and the cost are low, and the obtained slurry is uniform, has relatively high viscosity while keeping relatively low filter loss, is used for slurry shield construction, and is good in pressure maintaining performance and good in use performance.

Description

Technical Field

[0001] The invention belongs to the technical field of shield construction, and in particular relates to a slurry making method for a slurry shield and shield slurry. Background Art

[0002] Slurry shield construction technology is widely used in soil excavation operations in underground projects, especially in soft soil layers and water-sensitive strata. The core principle is to form a slightly permeable mud film on the excavation surface to balance the water and soil pressure through mud pressure and ensure the stability of the excavation surface. In this construction, mud plays a vital role as a support, isolation and lubrication medium. However, in actual construction, the stability of mud performance and the ability to form mud films often face a series of challenges, such as sedimentation caused by uncertain mud dispersion and the inability of mud films to effectively balance water and soil pressure, which will directly affect the normal operation of the shield machine.

[0003] Commonly used mud base materials are natural clays such as bentonite, supplemented with admixtures such as thickeners and flocculants, and through precise proportions, mud with ideal properties is formed. Adding admixtures to mud helps to enhance the homogeneity of mud and increase its viscosity during the mud formation process. For example, thickeners or flocculants can improve its mixing uniformity and rheological properties and improve mud stability. The viscosity of mud is one of the key factors affecting its performance. Higher viscosity helps to enhance the stability of mud and the ability to form mud films, but the thicker the mud, the longer it takes to prepare. Higher viscosity will prolong the stirring time, and during the slurry return process, waste slurry particles that are difficult to settle will affect the quality of the mud, resulting in a decrease in mud performance. Therefore, how to balance viscosity, film-forming properties and workability in the preparation of mud has become a problem that must be solved in construction.

[0004] The traditional mud preparation method usually uses bentonite as the base material, adds pre-made thickeners, flocculants and other additives, and injects the mud into the slurry mixing tank after stirring evenly, and mixes it with the return slurry, and then sends the mud to the cutterhead through a shield pump. The advantage of this method is that after the mud is stirred evenly, it usually has a higher viscosity, better stability and lower filtration loss, which can effectively support the excavation surface and reduce water seepage. However, the disadvantage of this method is that the dispersion process is relatively slow, and the poor dispersibility of bentonite may cause part of the mud to sink to the bottom or adhere to the pool wall, resulting in a waste of resources. In addition, the preparation of high-concentration mud requires a long stirring time, which increases the construction cost.

[0005] Therefore, how to improve the dispersibility of mud, shorten the mud preparation time, and reduce waste has become a technical problem that needs to be solved urgently in slurry shield construction. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a slurry making method for a slurry shield and shield mud, so as to improve the dispersibility of the shield mud and shorten the mud preparation time.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a slurry making method for a slurry shield, wherein the raw materials of the slurry making method include bentonite, a water reducing agent and an admixture, and the slurry making method includes the following steps:

[0009] The water reducing agent mother solution and the bentonite are mixed under stirring to obtain a premix, and the premix is ​​mixed with an admixture while maintaining stirring to obtain shield mud.

[0010] The slurry making method provided by the present invention preferentially mixes a water reducing agent with a base material bentonite, and a water reducing agent (PCE) is a superplasticizer, which can reduce the interfacial tension between a solution and solid particles added to the solution, so that the bentonite base material of the mud is dispersed more quickly and fully, and then other admixtures are added, and the admixture has the functions of increasing viscosity and retaining water, and stabilizing the mud, and its viscosity per unit concentration is much higher than that of the base material, and the dosage is small and difficult to disperse, therefore, the dispersion time is long, and it must be added after the base material is fully dispersed. Through the specific addition sequence of the raw materials, the obtained slurry is uniform, and the preparation consumes less time. At the same time, the slurry has high viscosity, low filtration loss, and good pressure retention performance, and the slurry can directly enter the slurry mixing tank to participate in the mud and water circulation of the shield construction.

[0011] Preferably, the water reducer comprises a polycarboxylate water reducer.

[0012] Preferably, the amount of the water reducing agent is 8-10 g / cm 3 , for example, it can be 8g / cm 3 、8.5g / cm 3 , 9g / cm 3 , 9.5g / cm 3 or 10g / cm 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0013] In the present invention, the polycarboxylate water reducer used is a commercially available liquid standard high-performance polycarboxylate water reducer that complies with GB 8076 and GB 8077 standards.

[0014] In the present invention, the solid content of the water reducing agent mother solution used is 40%.

[0015] Preferably, the amount of the water reducing agent mother solution is 20-25 mL / m 3 , for example, it can be 20mL / m 3 , 21mL / m3 , 22mL / m 3 , 23mL / m 3 , 24mL / m 3 or 25 mL / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the bentonite comprises calcium-based bentonite.

[0017] Preferably, the amount of bentonite used is 0.9-1.1 kg / m 3 , for example, it can be 0.9kg / m 3 , 0.95kg / m 3 , 1.0kg / m 3 1.05kg / m 3 or 1.1kg / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the stirring time of the water reducing agent mother solution and bentonite is 3-5 s / m based on the volume of the obtained slurry. 3 , for example, it can be 3s / m 3 , 3.5s / m 3 , 4s / m 3 , 4.5s / m 3 or 5s / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0019] Preferably, the additives include a thickener, a flocculant and a positively charged gel.

[0020] The thickener sodium polyacrylate (ASAP) is the main thickener. Its long-chain structure forms a spatial network structure with the substrate, and is balanced with the steric hindrance of the comb-shaped water reducer in the mud. After the front of the cutterhead contacts the soil, the overall moisture content decreases, and the network structure appears. The mud film formed has strong pressure and permeability resistance, can better support the excavation surface, and achieve low filtration loss; the positively charged gel dispersed particles have a high zeta potential and can polarize water molecules, forming a stable polarized complex with the negatively charged substrate particles. This complex has special rheological properties, the static shear force of the mud is increased, which is conducive to the suspension and carrying of sand and gravel, and the shear thinning performance is enhanced, which reduces the scouring effect of the mud on the excavation surface and prevents pressure fluctuations from breaking through the formation.

[0021] Preferably, the thickener comprises sodium polyacrylate.

[0022] Preferably, the amount of the thickener is 18-22 g / m 3, for example, it can be 18g / m 3 , 19g / m 3 , 20g / m 3 , 21g / m 3 or 22g / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0023] In the present invention, the molecular weight of the sodium polyacrylate is in the range of 8-10 million.

[0024] Preferably, the flocculant comprises sodium alginate.

[0025] Preferably, the amount of the flocculant used is 5-8 g / m 3 , for example, it can be 5g / m 3 , 6g / m 3 , 7g / m 3 or 8g / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0026] Preferably, the amount of the positive electrode glue used is 8-10 g / m 3 , for example, it can be 8g / m 3 , 8.5g / m 3 , 9g / m 3 , 9.5g / m 3 or 10g / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the stirring time of the premix and the admixture is 8-10 s / m based on the volume of the obtained slurry. 3 , for example, it can be 8s / m 3 , 8.5s / m 3 , 9s / m 3 , 9.5s / m 3 or 10s / m 3 , but not limited to the listed values, other unlisted values ​​within the numerical range are also applicable.

[0028] Preferably, in the slurry making method, the stirring speed is 45-75rpm, for example, it can be 45rpm, 50rpm, 55rpm, 60rpm, 65rpm, 70rpm or 75rpm, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0029] Preferably, in the slurry making method, a stirrer is used for stirring.

[0030] Preferably, the traveling speed of the mixing head of the mixer is 10-15 m / min, for example, it may be 10 m / min, 11 m / min, 12 m / min, 13 m / min, 14 m / min or 15 m / min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0031] Preferably, the stirring mode of the mixer includes: along the axial direction of the stirring head of the mixer, the spacing between the stirring blade groups is 0.8-1.0m, and along the axial direction perpendicular to the stirring head of the mixer, the spacing between the stirring blade groups is 1.0-1.5m.

[0032] Among them, along the axial direction of the mixing head of the mixer, the spacing of the mixing blade group is 0.8-1.0m, for example, it can be 0.8m, 0.85m, 0.9m, 0.95m or 1.0m, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0033] Along the axial direction perpendicular to the mixing head of the mixer, the spacing of the mixing blade group is 1.0-1.5m, for example, it can be 1.0m, 1.1m, 1.2m, 1.3m, 1.4m or 1.5m, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0034] In a second aspect, the present invention provides a shield slurry, wherein the shield slurry is obtained by the slurry making method described in the first aspect.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The slurry making method provided by the present invention designs a specific base material and an addition sequence of an admixture, so that the slurry making process takes less time, the material usage and the cost are low, the obtained slurry is uniform, and while maintaining a low filtration loss, it has a high viscosity, is used for slurry shield construction, has good pressure retention performance, and good performance in use. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further illustrated below through specific implementation methods.

[0038] In order to clearly illustrate the technical solution of the present invention, in a specific implementation manner, in the mixer, a group of blades is arranged every 0.9 m along the axial direction of the mixing head, and a group of blades is arranged every 1.2 m along the axial direction perpendicular to the mixing head.

[0039] Example 1

[0040] This embodiment provides a slurry making method for a slurry shield, the slurry making method comprising the following steps:

[0041] (1) Weigh the materials required for slurry making respectively. According to the slurry water volume, the mother liquor of standard polycarboxylate water reducer (PCE) (solid content 40%) is 22mL / m 3 , sodium polyacrylate (ASAP) powder (molecular weight 8-10 million) 20g / m 3 , MMH positive adhesive 9g / m 3 , sodium alginate powder 6g / m 3 ;

[0042] (2) Turn on the mixer, set the stirring speed to 60 rpm, and the moving speed of the stirring head to 12 m / min. Add water to the mixer, add the water reducer mother liquor, and then add calcium-based bentonite. The amount of calcium-based bentonite is 1.0 kg / m according to the amount of mud water. 3 , and continue stirring. The stirring time is 4s / m according to the volume of the obtained slurry. 3 ;

[0043] (3) Keep stirring and add sodium polyacrylate, positive electrode gel and sodium alginate into the mixer at the same time. The stirring time is 9 s / m based on the volume of the obtained slurry. 3 , and shield mud is obtained.

[0044] Example 2

[0045] This embodiment provides a slurry making method for a slurry shield, the slurry making method comprising the following steps:

[0046] (1) Weigh the materials required for slurry making respectively, according to the slurry water volume, standard polycarboxylate water reducer (PCE) mother liquor (solid content 40%) 20mL / m 3 , sodium polyacrylate (ASAP) powder (molecular weight 8-10 million) 18g / m 3 , MMH positive adhesive 10g / m 3 , sodium alginate powder 5g / m 3 ;

[0047] (2) Turn on the mixer, set the stirring speed to 45 rpm, and the moving speed of the stirring head to 15 m / min. Add water to the mixer, add the water reducer mother liquor, and then add calcium-based bentonite. The amount of calcium-based bentonite is 0.9 kg / m according to the amount of mud water. 3 , stirring was continued, and the stirring time was 5s / m according to the volume of the obtained slurry 3 ;

[0048] (3) Keep stirring and add sodium polyacrylate, positive electrode gel and sodium alginate into the mixer at the same time. The stirring time is 8s / m based on the volume of the obtained slurry. 3 , and shield mud is obtained.

[0049] Example 3

[0050] This embodiment provides a slurry making method for a slurry shield, the slurry making method comprising the following steps:

[0051] (1) Weigh the materials required for slurry making respectively, according to the slurry water volume, standard polycarboxylate water reducer (PCE) mother liquor (solid content 40%) 25mL / m 3 , sodium polyacrylate (ASAP) powder (molecular weight 8-10 million) 22g / m 3 , MMH positive adhesive 8g / m 3 , sodium alginate powder 8g / m 3 ;

[0052] (2) Turn on the mixer, set the stirring speed to 75 rpm, and the moving speed of the stirring head to 10 m / min. Add water to the mixer, add the water reducer mother liquor, and then add calcium-based bentonite. The amount of calcium-based bentonite is 1.1 kg / m according to the amount of mud water. 3 , stirring was continued, and the stirring time was 3s / m according to the volume of the obtained slurry 3 ;

[0053] (3) Keep stirring and add sodium polyacrylate, positive electrode gel and sodium alginate into the mixer at the same time. The stirring time is 10 s / m based on the volume of the obtained slurry. 3 , and shield mud is obtained.

[0054] Example 4

[0055] This embodiment provides a slurry making method for a slurry shield. Compared with Embodiment 1, no positive electrode glue is added in step (3), and the rest is the same as Embodiment 1.

[0056] Comparative Example 1

[0057] This comparative example provides a pulping agent, which is a commercially available HS-1 pulping agent.

[0058] The slurrying agent is the shield slurrying agent HS-1 provided by Hebei Renqiu Chaoyu Petroleum Additives Co., Ltd.

[0059] The components of the pulping agent include polyacrylic acid salts, cellulose salts, polyacrylonitrile salts, anti-calcifiers, modified soil and synergistic additives.

[0060] Comparative Example 2

[0061] This comparative example provides a pulping agent, which is a commercially available HS-3 pulping agent.

[0062] The slurrying agent is the shield slurrying agent HS-3 provided by Hebei Renqiu Chaoyu Petroleum Additives Co., Ltd.

[0063] The components of the pulping agent include polyacrylic acid salts, polyacrylonitrile salts, cellulose salts, vinyl multi-monomer copolymers, positive gel, micropore plugging expansion agent, modified soil and synergistic additives.

[0064] Comparative Example 3

[0065] This comparative example provides a slurrying agent, which is calcium-based bentonite.

[0066] Comparative Example 4

[0067] This comparative example provides a slurrying agent, and the raw materials of the slurrying agent include: calcium-based bentonite, standard polycarboxylic acid water-reducing agent, sodium polyacrylate powder, MMH positive electrode gel and sodium alginate powder.

[0068] The amount of the constituent raw materials in the slurrying agent is the same as that in Example 1, measured by the amount of water used in the slurry.

[0069] The pulping agent is obtained by directly mixing the constituent raw materials according to the usage amounts.

[0070] Comparative Example 5

[0071] This comparative example provides a slurry making method for a slurry shield, the slurry making method comprising the following steps:

[0072] (1) Weigh the materials required for slurry making respectively. According to the slurry water volume, the mother liquor of standard polycarboxylate water reducer (PCE) (solid content 40%) is 22mL / m 3 , sodium polyacrylate (ASAP) powder (molecular weight 8-10 million) 20g / m 3 , MMH positive adhesive 9g / m 3 , sodium alginate powder 6g / m 3 ;

[0073] (2) Turn on the mixer, add water and calcium-based bentonite. The amount of calcium-based bentonite is 1.0 kg / m according to the amount of mud water. 3 , sodium polyacrylate, positive electrode gel and sodium alginate are added to the mixer, and the stirring time is 9s / m according to the volume of the obtained slurry. 3 ;

[0074] (3) Keep stirring and add water reducing agent mother liquid into the mixer. The stirring time is 4s / m based on the volume of the obtained slurry. 3 , and shield mud is obtained.

[0075] That is, compared with Example 1, the order of adding the water reducing agent and the admixture in step (2) and step (3) is swapped, and the rest is the same as Example 1.

[0076] Comparative Example 6

[0077] This comparative example provides a slurry making method for a slurry shield. Compared with Example 1, no water reducing agent is added in step (2), and the rest is the same as Example 1.

[0078] Performance Testing

[0079] The pulping agent provided in the comparative example was added into the water at a dosage of 1.5 kg / m 3 , stirring to make slurry, the stirring speed is 300rpm, the stirring time is 8min, and 1L of shield mud is prepared respectively.

[0080] The shield mud provided in the embodiments and comparative examples was subjected to performance tests, and the obtained results are listed in Table 1.

[0081] The test method for the undispersed mass is as follows: the slurry is filtered using a 4.75 mm standard sieve, and the unscreened component and the precipitated component are weighed without drying before weighing.

[0082] The mud density, Marsh funnel viscosity and 1h colloid rate are tested in accordance with Appendix K of "JTG / T 3650-2020 Technical Specifications for Highway Bridge and Culvert Construction".

[0083] API filtration loss is tested in accordance with GB / T 5005-2010 Drilling Fluid Material Specification.

[0084] Table 1

[0085]

[0086] It can be seen from Table 1 that the mud components prepared by the slurry making method provided by the present invention are completely dispersed, and have extremely low fluid loss while maintaining high viscosity and colloid rate. Compared with Example 1, in Example 4, the fluid loss of the mud increases without adding positive gel, and the MMH positive gel is beneficial to increase the viscosity of the mud after uniform dispersion and reduce the fluid loss.

[0087] Compared with Example 1, in Comparative Examples 1-3, under the condition of the same amount of materials added, the present method is better than the two pulping agents HS-1 and HS-3 on the market in various indicators, and is also much higher than the performance of using only bentonite; in Comparative Examples 4-5, when the same ratio is used for pulping, adding PCE later or adding all materials at the same time will cause the thickener and bentonite to be unable to be fully dispersed within the same time; in Comparative Example 6, this phenomenon is aggravated by not adding PCE, which seriously reduces the viscosity and colloid rate of the homogeneous slurry body, increases the filtration loss, and has poor film-forming properties.

[0088] Due to the small total amount of addition, the various adjustments have little effect on the mud density. When the order of addition remains unchanged, the effect of the amount of each thickener on the dissolution process is weaker than that of PCE, but the effect on the various properties of the mud is stronger than that of PCE.

[0089] In summary, the slurry making method provided by the present invention takes less time to make slurry, has low material consumption and cost, and the obtained slurry is uniform by designing a specific base material and the order of adding admixtures. It has high viscosity while maintaining a low filtration loss, and is used for mud shield construction, with good pressure retention performance and good performance in use.

[0090] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A slurry making method for a slurry shield, characterized in that: The raw materials of the pulping method include bentonite, a water reducing agent and an admixture, and the pulping method includes the following steps: The water reducing agent mother solution and the bentonite are mixed under stirring to obtain a premix, and the premix is ​​mixed with an admixture while maintaining stirring to obtain shield mud.

2. The pulping method according to claim 1, characterized in that: The water reducer includes a polycarboxylate water reducer; Preferably, the amount of the water reducing agent is 8-10 g / cm 3 .

3. The pulping method according to claim 1 or 2, characterized in that: The bentonite includes calcium-based bentonite; Preferably, the amount of bentonite used is 0.9-1.1 kg / m 3 .

4. The pulping method according to any one of claims 1 to 3, characterized in that: The stirring time of the water reducing agent mother solution and bentonite is 3-5s / m based on the volume of the obtained slurry. 3 .

5. The pulping method according to any one of claims 1 to 4, characterized in that: The additives include a thickener, a flocculant and a positive-electrolyte gel.

6. The pulping method according to claim 5, characterized in that: The thickener includes sodium polyacrylate; Preferably, the amount of the thickener is 18-22 g / m 3 .

7. The pulping method according to claim 5 or 6, characterized in that: The flocculant includes sodium alginate; Preferably, the amount of the flocculant used is 5-8 g / m 3 ; Preferably, the amount of the positive electrode glue used is 8-10 g / m 3 .

8. The pulping method according to any one of claims 1 to 7, characterized in that: The stirring time of the premix and the admixture is 8-10 s / m based on the volume of the obtained slurry. 3 .

9. The pulping method according to any one of claims 1 to 8, characterized in that: In the slurry making method, the stirring speed is 45-75 rpm; Preferably, in the pulping method, a stirrer is used for stirring; Preferably, the moving speed of the mixing head of the mixer is 10-15 m / min; Preferably, the stirring mode of the mixer includes: along the axial direction of the stirring head of the mixer, the spacing between the stirring blade groups is 0.8-1.0m, and along the axial direction perpendicular to the stirring head of the mixer, the spacing between the stirring blade groups is 1.0-1.5m.

10. A shield slurry, characterized in that: The shield slurry is obtained by the slurry making method according to any one of claims 1-9.

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