New type of wall protection slurry material for super deep diaphragm wall and preparation method thereof

Abstract

The present application relates to a kind of new type of wall protection mud material for ultra-deep underground continuous wall and its preparation method, comprising the following steps: pour mixing water into the first container, while adding bentonite, the first container is stirred to be uniformly dispersed;Sodium carbonate, sodium carboxymethyl cellulose, xanthan gum and silicone acrylic emulsion are mixed and added to mixing water and poured into the second container, and stirred to be fully hydrated;Mix the solution in the first container and the second container, stir to be fully mixed, complete mud preparation.The beneficial effects of the present application are: it can avoid the hidden troubles such as excessive lateral earth pressure, large amount of mud loss, thin and dense mud skin cannot be formed when the excavation depth of underground continuous wall is large, configure a new type of modified bentonite wall protection mud with suitable physical stability and chemical stability, appropriate relative density, good mud skin forming property, which can adapt to the working condition of ultra-deep underground continuous wall, avoid the occurrence of hole collapse and shrinkage phenomenon, so as to ensure the quality of slotting and construction safety.

Description

Technical Field

[0001] This invention belongs to the field of geotechnical engineering building materials technology, and in particular relates to a novel wall-protecting mud material for ultra-deep underground continuous walls and its preparation method. Background Technology

[0002] With the continuous development of urbanization and infrastructure construction in my country, the importance of deep foundation pit engineering has been increasingly recognized, and it has been widely used in various engineering constructions. Meanwhile, diaphragm walls, due to their advantages such as high wall rigidity, good integrity, strong impermeability, and reliable quality, can be constructed in urban areas with minimal vibration and low noise. They can be built close to existing buildings and are suitable for various foundation conditions. Therefore, they have become an important engineering method in foundation pit engineering, effectively serving as waterproofing and retaining structures to adapt to the increase in high-rise and super high-rise buildings and the development of subway construction.

[0003] Due to the application of advanced trenching equipment and new processes such as grab buckets, bentonite slurry is now the primary type of slurry used in diaphragm wall trenching, replacing the denser clay slurry. Currently, in practical engineering applications, dispersible slurry composed of fresh water, bentonite, and dispersing agents is still the main type used. These agents include soda ash, caustic soda, and sodium carboxymethyl cellulose (CMC), and for most engineering conditions, only the proportions of these components are adjusted, with little research on additives. However, when ultra-deep diaphragm walls with excavation depths exceeding 15m are involved, the excessive excavation depth can cause the trench walls to bear significant lateral earth pressure, which is even more pronounced under conditions of multiple confined water heads. Simultaneously, with increasing trench depth, other unstable factors on the trench walls also increase, especially in silty sand and fine sand strata, which are prone to trench wall instability and borehole collapse. Furthermore, the sediment at the bottom of the trench is difficult to remove, leading to a reduction in the bearing capacity of the diaphragm wall and potentially creating piping risks.

[0004] Therefore, it is particularly important to study a new type of wall-protecting mud material for the construction of ultra-deep underground continuous walls. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a novel wall-protecting mud material for ultra-deep underground continuous walls and its preparation method.

[0006] This novel wall-protecting slurry material for ultra-deep underground continuous walls comprises: water, bentonite, soda ash, sodium carboxymethyl cellulose, xanthan gum, and silicone-acrylic emulsion. The mass percentages of each component are as follows: bentonite 5.0%–10.0%, soda ash 0.2%–0.5%, xanthan gum 0.05%–0.5%, sodium carboxymethyl cellulose 0.1%–0.5%, silicone-acrylic emulsion 0%–2.0%, with the balance being mixing water.

[0007] Preferably, the bentonite is sodium-based bentonite with a particle size of 500-600 mesh.

[0008] Preferably, the soda ash is anhydrous sodium carbonate.

[0009] Preferably, the bentonite content is 8.0% of the total mass; the soda ash content is 0.3% of the total mass; the sodium carboxymethyl cellulose content is 0.1% to 0.3% of the total mass; the xanthan gum content is 0.05% to 0.1% of the total mass; and the silicone-acrylic emulsion content is 0% to 2.0% of the total mass.

[0010] The preparation method of this novel wall-supporting mud material for ultra-deep underground continuous walls includes the following steps:

[0011] S1. Design the mud mix ratio according to the composition of the foundation soil. Based on the mud mix ratio, weigh out the corresponding amounts of water, bentonite, soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone acrylic emulsion.

[0012] S2. Pour the mixing water into the first container, and while adding the bentonite, stir the first container until it is evenly dispersed;

[0013] S3. Mix soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone acrylic emulsion, add to the mixing water and pour into the second container, and stir until fully hydrated;

[0014] S4. Mix the solutions in the first and second containers and stir until fully mixed to complete the mud preparation.

[0015] As a preferred option, step S5 follows step S4. Step S5 is a mud performance test: First, prepare experimental instruments according to the performance indicators to be tested; then, swell the prepared mud for 24 hours to form a mud sample; select appropriate experimental instruments to test the various performance indicators of the mud sample. If the various performance indicators of the mud do not meet the requirements, then prepare the mud again by adjusting the mud mix ratio.

[0016] Preferably, the indicators include one or more of viscosity, API filtration loss, mud cake thickness, specific gravity, sand content, and pH value, and the experimental instruments include any one or more of Marshall funnel viscometer, medium-pressure filtration loss meter, vernier caliper, mud hydrometer, sand content meter, pH test paper, and standard colorimetric card.

[0017] Preferably, the performance indicators include a specific gravity of 1.03 to 1.10, a viscosity of 25s to 35s, an API filtration loss of <15ml / 30min, a mud cake thickness of <1.5mm / 30min, and a pH between 8 and 9.

[0018] The beneficial effects of this invention are:

[0019] 1) The mud material prepared by the method described in this invention can avoid the hidden dangers such as excessive lateral earth pressure, large amount of mud loss, and inability to form a thin and dense mud cake when the excavation depth of the diaphragm wall is large. It can formulate a new type of modified bentonite wall protection mud with suitable physical and chemical stability, appropriate relative density, good mud cake formation, and adaptability to ultra-deep diaphragm wall working conditions, so as to avoid the occurrence of hole collapse and hole shrinkage, thereby ensuring the quality of trenching and construction safety.

[0020] 2) The mud of this invention uses water, bentonite, soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone-acrylic emulsion as raw materials. The main raw material of the mud formula, sodium-based bentonite, has a low cost and can significantly improve the wall protection effect of the mud while reducing engineering costs. At the same time, the raw materials do not have high requirements for storage conditions, the preparation process is simple and quick, and the experience requirements of the operators are not high.

[0021] 3) The mud formulation material proposed in this invention is environmentally friendly and has a low pollution rate. Attached Figure Description

[0022] Figure 1 Flowchart for mud preparation;

[0023] Figure 2 The figure shows the experimental results of the effect of single factors on the viscosity of mud materials;

[0024] Figure 3 Figure 1 shows the experimental results of the effect of single factors on filtration loss of mud materials.

[0025] Figure 4 The figure shows the experimental results of the effect of single factors on mud cake thickness of mud materials;

[0026] Figure 5 The following is a graph showing the mud viscosity test results for the example group;

[0027] Figure 6 The diagram shows the slurry filtration loss test results for the example group.

[0028] Figure 7 This is a diagram of the mud and mud cake thickness test in the example group. Detailed Implementation

[0029] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0030] Example 1

[0031] As one example, such as Figure 1As shown, the preparation method of this novel wall-supporting mud material for ultra-deep underground continuous walls includes the following steps:

[0032] S1. Design the mud mix ratio according to the composition of the foundation soil. According to the mud mix ratio, weigh the corresponding amounts of water, bentonite, and polymer, where the polymer includes soda ash, sodium carboxymethyl cellulose, xanthan gum, and silicone acrylic emulsion.

[0033] S2. Pour the mixing water into the first container, and while adding the bentonite, stir the first container until it is evenly dispersed;

[0034] S3. Mix soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone acrylic emulsion, add to the mixing water and pour into the second container, and stir until fully hydrated;

[0035] S4. Mix the solutions in the first and second containers and stir until fully mixed to complete the mud preparation.

[0036] Step S5, Mud Performance Testing: First, select the test indicators and prepare the experimental instruments; then, swell the prepared mud for 24 hours to form a mud sample and test the corresponding indicators.

[0037] Specifically, one or more of the following instruments are selected: Marshall funnel viscometer, medium-pressure filtration loss meter, vernier caliper, mud hydrometer, sand content meter, pH test paper, and standard colorimetric card. The viscosity, API filtration loss, mud cake thickness, specific gravity, sand content, and pH value of the mud sample are tested. If the performance indicators of the mud do not meet the requirements, the mud mix ratio is adjusted and the mud is re-prepared.

[0038] According to the standard DB33 / T 1233-2021 "Technical Specification for Diaphragm Walls in Zhejiang Province", the specific gravity, funnel viscosity, API filtration loss, mud cake thickness, and pH value of bentonite slurry are all important indicators for controlling slurry performance. The performance indicators of newly prepared bentonite slurry should meet the following requirements:

[0039] The specific gravity should be between 1.03 and 1.10, the viscosity between 20 and 25 seconds in cohesive soils and between 25 and 35 seconds in sandy soils, the water loss should be below 15 ml / 30 min, the mud cake thickness should be below 1.5 mm / 30 min, and the pH should be between 8 and 9. If the prepared bentonite slurry does not meet the specifications, it will be difficult to achieve a good wall protection effect, and it will also have an adverse effect on the performance of concrete pouring and after concrete hardening.

[0040] Example 2

[0041] As another embodiment, this embodiment two is proposed based on embodiment one. The components of this novel wall-protecting mud material for ultra-deep underground continuous walls include: water, bentonite, soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone acrylic emulsion.

[0042] Bentonite is sodium-based bentonite with a particle size of 500-600 mesh.

[0043] The soda ash is anhydrous sodium carbonate.

[0044] The mass percentages of each component are as follows: sodium bentonite content is 8.0% of the total mass; soda ash content is 0.3% of the total mass; sodium carboxymethyl cellulose content is 0.1% to 0.3% of the total mass; xanthan gum content is 0.05% to 0.1% of the total mass; silicone acrylic emulsion content is 0% to 2.0% of the total mass; and the balance is mixing water.

[0045] Based on the above-mentioned proportion range proposed in this embodiment, experiments were conducted with sodium carboxymethyl cellulose added at a mass percentage of 0.1% and 0.3%, xanthan gum added at a mass percentage of 0.05% and 0.1%, and silicone-acrylic emulsion added at a mass percentage of 0%, 0.5%, 1%, and 2%.

[0046] Specifically, it is divided into four sets of implementation examples:

[0047] First embodiment group: sodium carboxymethyl cellulose 0.1%, xanthan gum 0.05%, silicone acrylic emulsion added at mass amounts of 0%, 0.5%, 1%, and 2%.

[0048] The second embodiment group consisted of: sodium carboxymethyl cellulose 0.3%, xanthan gum 0.05%, and silicone-acrylic emulsion added at mass amounts of 0%, 0.5%, 1%, and 2%.

[0049] The third example group consisted of 0.1% sodium carboxymethyl cellulose, 0.1% xanthan gum, and silicone-acrylic emulsions added at mass amounts of 0%, 0.5%, 1%, and 2%.

[0050] The fourth example group consisted of: sodium carboxymethyl cellulose 0.3%, xanthan gum 0.1%, and silicone-acrylic emulsions added at mass levels of 0%, 0.5%, 1%, and 2%. The remaining amount was water for mixing.

[0051] Meanwhile, a control group was prepared by mixing sodium bentonite at a mass addition of 8.0% and soda ash at a mass addition of 0.3%, i.e., no other polymers were added.

[0052] Table 1 Composition and proportion of mud materials in each group

[0053]

[0054] Following the above proportions and using the method proposed in Example 1, a total of 17 groups of mud materials were prepared, including four example groups and a control group. Their compositions are shown in Table 1. The 17 groups of mud materials were then subjected to mud performance tests, and the results are shown in Tables 2 and 3. Figures 5 to 7 As shown.

[0055] Table 2 Test results of various indicators of mud materials

[0056]

[0057] Specifically, to verify the fluidity and deformation characteristics of the 17 groups of mud materials, a Marshall funnel viscometer was used to measure the viscosity of the mud. Higher mud viscosity indicates a stronger slag-carrying capacity and a shorter penetration distance in the formation, which is beneficial for the rapid formation of a high-quality mud cake. However, increased mud viscosity also makes mud pumping extremely difficult.

[0058] The viscosity test results of 17 groups of mud materials in the four example groups and the control group were analyzed, such as Figure 2 As shown, the viscosity of the prepared slurry improved to varying degrees with increasing percentage of silicone-acrylic emulsion. Groups 3 through 7 showed the most significant viscosity improvement. The improvement effect varied slightly depending on the amount of sodium carboxymethyl cellulose, silicone-acrylic emulsion, and xanthan gum added. Figure 2 As shown, the viscosity increases significantly with the increase of xanthan gum content, and first increases and then decreases with the increase of sodium carboxymethyl cellulose and silicone-acrylic emulsion content.

[0059] To verify the stability of the 17 mud materials, a medium-pressure filtration loss meter was used to measure the API filtration loss and mud cake thickness. Excessive API filtration loss would result in an excessively thick and loose mud cake, negatively impacting the project.

[0060] Analysis of the API filtration loss and mud cake thickness test results of 17 groups of mud materials in four example groups and a control group showed that with the addition of silicone-acrylic emulsion, both the API filtration loss and mud cake thickness of the mud materials showed a significant decreasing trend. Simultaneously, the increased addition of xanthan gum, silicone-acrylic emulsion, and sodium carboxymethyl cellulose also improved the stability of the mud materials to some extent. Figure 3 As shown in the figure. Among them, the viscosity improvement effect of groups 2-11 and 13-17 is more ideal, that is, the mud materials except for the control group and group 12 all meet the requirements.

[0061] To verify the wall support performance of 17 sets of drilling mud in ultra-deep formations, an NB-1 hydrometer was used to measure the specific gravity of the mud. Excessive specific gravity leads to increased water loss from the mud, and also requires greater power for mud circulation, potentially affecting the trenching machine. Conversely, if the specific gravity is too low, although the mud can be pumped smoothly, filtration loss within the formation will also increase.

[0062] The specific gravity test results of 17 mud materials in four control examples and control groups were analyzed. The effects of silicone acrylic emulsion, xanthan gum and sodium carboxymethyl cellulose on specific gravity were relatively small. The specific gravity of each mud group was about 1.04 to 1.06, which can meet the requirements of fresh mud in cohesive and sandy soils.

[0063] To verify the compactness of the mud cake in 17 mud samples, the sand content of the mud was measured using a NA-1 sand content meter. An excessively high sand content will reduce the viscosity of the mud, causing the mud cake to become loose, ultimately reducing the mud's wall-protecting properties and increasing the difficulty of borehole cleaning and sediment removal.

[0064] Analysis of the sand content test results of 17 groups of mud materials in four example groups and a control group revealed that the experimental groups with higher viscosity had relatively lower sand content, indicating a certain correlation between sand content and viscosity. Except for the control group, the sand content of the prepared mud materials was generally between 3% and 5%, which meets the requirements for newly prepared mud in cohesive and sandy soils.

[0065] To verify the mud cake compactness of the 17 mud samples, pH test paper and a standard colorimetric card were used to measure the pH of the mud. Excessive sand content leads to a decrease in mud viscosity, causing the mud cake to become loose, ultimately reducing the mud's wall-protecting properties and increasing the difficulty of borehole cleaning and sediment removal.

[0066] Analysis of the pH test results of 17 groups of mud materials in four example groups and control groups shows that the pH value of each mud material generally increased with the increase of the amount of each additive, but except for groups 16 and 17, it remained between 8 and 9, which can meet the pH requirements of mud materials used in diaphragm walls.

[0067] Based on the above results, a total of 17 mud materials were obtained in the four example groups and the control group in this embodiment. After screening, groups 3 to 7 showed better wall protection performance. These mud materials have lower sand content, more stable viscosity, less filtration loss, and thinner and denser mud cake, which can avoid accidents such as hole collapse and necking during the construction of diaphragm walls, thereby ensuring the quality of trenching and the safety of construction.

[0068] It should be noted that the parts in this embodiment that are the same as or similar to those in Embodiment 1 can be referred to each other, and will not be repeated in this application.

[0069] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

Claims

1. A novel wall-supporting slurry material for ultra-deep underground continuous walls, characterized in that, Its components include: water, bentonite, soda ash, sodium carboxymethyl cellulose, xanthan gum, and silicone-acrylic emulsion. The mass percentages of each component are as follows: bentonite 5.0%–10.0%, soda ash 0.2%–0.5%, xanthan gum 0.05%–0.5%, sodium carboxymethyl cellulose 0.1%–0.5%, silicone-acrylic emulsion 0.5%–2.0%, and the balance is mixing water.

2. The novel wall-protecting slurry material for ultra-deep underground continuous walls according to claim 1, characterized in that, Bentonite is sodium-based bentonite with a particle size of 500-600 mesh.

3. The novel wall-protecting slurry material for ultra-deep underground continuous walls according to claim 1, characterized in that, The soda ash is anhydrous sodium carbonate.

4. The novel wall-protecting slurry material for ultra-deep underground continuous walls according to claim 1, characterized in that, The bentonite content is 8.0% of the total mass; the soda ash content is 0.3% of the total mass; the sodium carboxymethyl cellulose content is 0.1% to 0.3% of the total mass; the xanthan gum content is 0.05% to 0.1% of the total mass; and the silicone-acrylic emulsion content is 0.5% to 2.0% of the total mass.

5. The method for preparing the novel wall-protecting slurry material for ultra-deep underground continuous walls as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Design the mud mix ratio according to the composition of the foundation soil. Based on the mud mix ratio, weigh out the corresponding amounts of water, bentonite, soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone acrylic emulsion. S2. Pour the mixing water into the first container, and while adding the bentonite, stir the first container until it is evenly dispersed; S3. Mix soda ash, sodium carboxymethyl cellulose, xanthan gum and silicone-acrylic emulsion, add them to the mixing water and pour them into the second container. Stir until fully hydrated. S4. Mix the solutions in the first and second containers and stir until fully mixed to complete the mud preparation.

6. The method for preparing the novel wall-protecting slurry material for ultra-deep underground continuous walls according to claim 5, characterized in that, After step S4, there is a step S5, which is the mud performance test: First, prepare the experimental instruments according to the performance indicators to be tested; then, the prepared mud swells for 24 hours to form a mud sample; select the appropriate experimental instruments to test the various performance indicators of the mud sample. If the various performance indicators of the mud do not meet the requirements, the mud mix ratio is adjusted and the mud is prepared again.

7. The method for preparing the novel wall-protecting slurry material for ultra-deep underground continuous walls according to claim 6, characterized in that, The indicators include one or more of viscosity, API filtration loss, mud cake thickness, specific gravity, sand content, and pH value. The experimental instruments include any one or more of the following: Marshall funnel viscometer, medium-pressure filtration loss meter, vernier caliper, mud hydrometer, sand content meter, pH test paper, and standard colorimetric card.

8. The method for preparing the novel wall-protecting slurry material for ultra-deep underground continuous walls according to claim 6, characterized in that, The performance indicators include a specific gravity of 1.03–1.10, a viscosity of 25–35 s, an API filtration loss of <15 ml / 30 min, a mud cake thickness of <1.5 mm / 30 min, and a pH between 8 and 9.

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