An under-reamed diaphragm wall slurry for pebble stratum and its preparation method

Abstract

This application relates to the technical field of underground engineering construction, and specifically discloses a slurry for protecting the wall of diaphragm wall in pebble stratum and a preparation method thereof. The slurry for protecting the wall of diaphragm wall in pebble stratum provided by this application comprises the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 5 - 10 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1 - 3 parts of KH792 modified polypropylene fiber, and 450 - 500 parts of water; further, the shell powder includes shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm; this application also provides a preparation method for the above-mentioned slurry for protecting the wall of diaphragm wall in pebble stratum. The slurry for protecting the wall of diaphragm wall in pebble stratum provided by this application has low cost, good wall protection effect, excellent stability of the formed groove wall, and can maintain non-collapse for 120 h, and can meet the construction requirements of diaphragm wall.

Description

Technical Field

[0001] This application relates to the technical field of underground engineering construction, and particularly to a slurry for protecting the wall of diaphragm wall in pebble stratum and a preparation method thereof. Background Art

[0002] In construction engineering, especially in the construction of diaphragm wall, the performance of the slurry directly affects the stability of the wall and the construction quality. With the accelerating development of urban construction, the pebble stratum, as a common geological condition, poses higher requirements for the construction of diaphragm wall. A reasonably configured slurry can not only effectively prevent the wall from collapsing, but also improve the construction efficiency, reduce the cost, and ensure the smooth progress of the project.

[0003] Currently, for the preparation of the slurry for protecting the wall of diaphragm wall in pebble stratum, there are mainly three types of formulas: one type is mainly composed of bentonite, and the rheological properties of the slurry are adjusted by adding appropriate viscosity increasing agents or thickening agents; another type is based on the mixture of bentonite and cement, and the wall protection performance and sedimentation stability of the slurry are improved by adjusting the ratio of the two and adding other chemical additives; there is also a type that is prepared by mixing a variety of mineral powders, such as kaolin, fly ash, etc., in combination with bentonite, to enhance the adaptability of the slurry in complex strata.

[0004] However, these conventional formulas have many deficiencies in the actual application in pebble stratum. Due to the complex structure, large spacing between stones, and easy water seepage in the pebble stratum, the groove wall is prone to collapse, the wall protection effect is insufficient, and a stable wall protection cannot be formed, which in turn affects the quality of the diaphragm wall. Summary of the Invention

[0005] In order to improve the wall protection performance of the slurry and the stability of the groove wall, this application provides a slurry for protecting the wall of diaphragm wall in pebble stratum and a preparation method thereof.

[0006] In the first aspect, this application provides a slurry for protecting the wall of diaphragm wall in pebble stratum, adopting the following technical solution: A slurry for protecting the wall of diaphragm wall in pebble stratum, comprising the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 5 - 10 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1 - 3 parts of KH792 modified polypropylene fiber, and 450 - 500 parts of water.

[0007] This application uses bentonite, cement, shell powder, etc. to prepare a slurry for the diaphragm wall in pebble stratum with excellent stability and good anti-seepage performance. By controlling the weight parts of each component within the above range, this slurry can not only effectively prevent groundwater seepage in the pebble stratum, but also adapt to the complex geological conditions of the pebble stratum, significantly improving the slurry support effect during the construction of the diaphragm wall, enabling the trench wall not to collapse within 150 hours, meeting the requirements of long-time construction of the diaphragm wall; and this slurry has good fluidity, which can greatly reduce the construction difficulty. In addition, the raw materials used in this slurry for the diaphragm wall have good economy and environmental protection characteristics, which is conducive to controlling construction costs and reducing environmental impact. In summary, the novel slurry provided by this application can achieve efficient and safe construction of the diaphragm wall on the premise of ensuring project quality.

[0008] Optionally, the slurry for the diaphragm wall in pebble stratum includes the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 6.5 - 8.5 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1.5 - 2.5 parts of KH792 modified polypropylene fiber

[0009] and 450 - 500 parts of water.

[0010] Optionally, the slurry for the diaphragm wall in pebble stratum includes the following components in parts by weight: 40 parts of bentonite, 25 parts of cement, 7.5 parts of shell powder, 5 parts of carboxymethyl cellulose, 2 parts of KH792 modified polypropylene fiber and 480 parts of water.

[0011] In some embodiments, the weight parts of the shell powder can be 5 - 6.5 parts, 5 - 7.5 parts, 5 - 8.5 parts, 5 - 10 parts, 6.5 - 7.5 parts, 6.5 - 8.5 parts, 6.5 - 10 parts, 7.5 - 8.5 parts, 7.5 - 10 parts or 8.5 - 10 parts.

[0012] In a specific embodiment, the weight parts of the shell powder can also be 5 parts, 6.5 parts, 7.5 parts, 8.5 parts or 10 parts.

[0013] In some embodiments, the weight parts of the KH792 modified polypropylene fiber can be 1 - 1.5 parts, 1 - 2 parts, 1 - 2.5 parts, 1 - 3 parts, 1.5 - 2 parts, 1.5 - 2.5 parts, 1.5 - 3 parts, 2 - 2.5 parts, 2 - 3 parts or 2.5 - 3 parts.

[0014] In a specific embodiment, the weight parts of the KH792 modified polypropylene fiber can also be 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0015] Optionally, the shell powder includes shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm.

[0016] In some embodiments, the shell powder may be a mixture of shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm, a mixture of shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 500 - 600 μm, or a mixture of shell powder with a particle size of 500 - 600 μm and shell powder with a particle size of 800 - 1000 μm.

[0017] Optionally, the weight ratio of the shell powder with a particle size of 100 - 200 μm to the shell powder with a particle size of 800 - 1000 μm is 1:(0.67 - 0.83).

[0018] In this application, through experimental exploration, it is found that by further using the shell powder with the above particle size ratio, the comprehensive performance of the viscosity, specific gravity, and filtration loss of the slurry for protecting the wall is better, and it can better meet the usage requirements of the diaphragm wall in the pebble stratum.

[0019] In some embodiments, the weight ratio of the shell powder with a particle size of 100 - 200 μm to the shell powder with a particle size of 800 - 1000 μm can be 1:(0.67 - 0.75) or 1:(0.75 - 0.83).

[0020] In a specific embodiment, the weight ratio of the shell powder with a particle size of 100 - 200 μm to the shell powder with a particle size of 800 - 1000 μm can also be 1:0.67, 1:0.75, or 1:0.83.

[0021] Optionally, the preparation method of the KH792 - modified polypropylene fiber includes the following steps: soaking polypropylene fiber in a 2 wt% KH792 solution for 24 h, with the weight ratio of polypropylene fiber to the KH792 solution being 1:6.5; then repeatedly washing the soaked polypropylene fiber with distilled water 3 times, and then putting it into a drying chamber with a relative humidity of 50 ± 5% to dry for 5 days until constant weight to obtain the KH792 - modified polypropylene fiber.

[0022] In this application, due to the non - polar characteristics of polypropylene fiber, it has hydrophobicity. When directly used in the slurry for protecting the wall, its dispersibility and fluidity are slightly poor, and agglomeration is likely to occur. In this application, by further modifying the polypropylene fiber, the obtained KH792 - modified polypropylene fiber can increase the fluidity and toughness of the slurry for protecting the wall, thereby greatly improving the crack - resistance performance of the slurry for protecting the wall and effectively avoiding the collapse of the groove wall.

[0023] Second, this application provides a method for preparing a slurry for protecting the wall of a diaphragm wall in a pebble stratum, including the following steps:

[0024] First, mix bentonite, shell powder and part of water, stir evenly and then let it stand for 8 - 10 h to obtain premix ①;

[0025] Then, mix cement, carboxymethyl cellulose, polypropylene fiber and the remaining water to obtain premix ②;

[0026] Mix premix ① and premix ② evenly to obtain the slurry for protecting the wall of the diaphragm wall in pebble stratum.

[0027] Optionally, the temperature for standing is 35 - 45 °C.

[0028] In summary, the present application has the following beneficial effects:

[0029] 1. The present application uses bentonite, cement, shell powder, etc. to prepare a slurry for protecting the wall, which has good stability and anti - permeability, can significantly improve the effect of protecting the wall during the construction of the diaphragm wall, making the groove wall not collapse within 150 h, and meeting the use requirements for the long - time construction of the diaphragm wall in pebble stratum.

[0030] 2. The present application further uses shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm to prepare the slurry for protecting the wall, and controls the weight ratio of the above - mentioned shell powder with different particle sizes within the range of 1:(0.67 - 0.83). The obtained slurry for protecting the wall has better comprehensive properties such as viscosity and filtration loss, and good fluidity during perfusion. When it is used for protecting the wall in pebble stratum, it can ensure no collapse within 180 h, and better meet the use requirements for the long - time construction operation of the diaphragm wall in pebble stratum. Specific Embodiments

[0031] The present application provides a slurry for protecting the wall of the diaphragm wall in pebble stratum, which comprises the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 5 - 10 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1 - 3 parts of KH792 modified polypropylene fiber and 450 - 500 parts of water. Further, the slurry for protecting the wall of the diaphragm wall in pebble stratum comprises the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 6.5 - 8.5 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1.5 - 2.5 parts of KH792 modified polypropylene fiber and 450 - 500 parts of water.

[0032] Among them, the shell powder includes shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm. Further, the weight ratio of the shell powder with a particle size of 100 - 200 μm to the shell powder with a particle size of 800 - 1000 μm is 1:(0.67 - 0.83).

[0033] The method for preparing the slurry for protecting the underground diaphragm wall in pebble stratum provided by this application includes the following steps:

[0034] (1) First, mix bentonite, shell powder and 2 / 3 of the total amount of water, stir evenly, and then let it stand at 35 - 45 °C for 8 - 10 h to obtain premix ①;

[0035] (2) Then, mix cement, carboxymethyl cellulose, KH792 modified polypropylene fiber and the remaining water to obtain premix ②;

[0036] (3) Mix premix ① and premix ② evenly to obtain the slurry for protecting the underground diaphragm wall in pebble stratum.

[0037] In this application, the bentonite is purchased from Zexu Mineral Products Trading Co., Ltd. in Lingshou County; the cement is P.W42.5 Portland cement; the shell powder is obtained by crushing the clam shell; the carboxymethyl cellulose is purchased from Zibo Daoqin New Materials Co., Ltd.; the polypropylene fiber is purchased from Tai'an Anfeng New Materials Technology Co., Ltd. The rest of the raw materials, reagents, solvents, etc. of this application can all be obtained through commercial purchase.

[0038] The following further elaborates on this application in combination with preparation examples, implementation examples and performance detection tests.

[0039] Examples 1 - 9

[0040] Examples 1 - 9 respectively provide a slurry for protecting the underground diaphragm wall in pebble stratum.

[0041] The difference between the above - mentioned examples lies in the addition amounts of shell powder and polypropylene fiber in the slurry for protecting the underground diaphragm wall, as shown in Table 1 below.

[0042] The method for preparing the slurry for protecting the underground diaphragm wall in pebble stratum provided by Examples 1 - 9 includes the following steps:

[0043] (1) First, mix 4 kg of bentonite, shell powder (particle size 800 - 1000 μm) and 32 kg of water, stir evenly, and then let it stand at 35 - 45 °C for 8 - 10 h to obtain premix ①;

[0044] (2) Then, mix 2 kg of cement, 0.5 kg of carboxymethyl cellulose, KH792 modified polypropylene fiber and 16 kg of water to obtain premix ②;

[0045] (3) Mix premix ① and premix ② evenly to obtain the slurry for protecting the underground diaphragm wall in pebble stratum.

[0046] Among them, the preparation method of KH792 modified polypropylene fiber is as follows: Soak polypropylene fiber in 2wt% KH792 solution for 24h, and the weight ratio of polypropylene fiber to KH792 solution is 1:6.5; Then repeatedly wash the soaked polypropylene fiber with distilled water 3 times, and then put it into a drying chamber with a relative humidity of 50±5% and dry it for 5 days until constant weight to obtain KH792 modified polypropylene fiber.

[0047] Table 1 The addition amounts of shell powder and KH792 modified polypropylene fiber in the slurry for protecting the wall in Examples 1-9

[0048]

[0049]

[0050] Examples 10-15

[0051] Examples 10-15 respectively provide a slurry for protecting the wall of diaphragm wall in pebble stratum.

[0052] The difference between the above examples and Example 3 is as follows: The particle size and proportion of shell powder are shown in Table 2 below.

[0053] Table 2 The particle size and proportion of shell powder in Examples 3, 10-15

[0054]

[0055] Comparative Example 1

[0056] Comparative Example 1 provides a slurry for protecting the wall of diaphragm wall in pebble stratum.

[0057] The difference between the above examples and Example 3 is as follows: Replace shell powder with barite powder of 1250 mesh.

[0058] Comparative Example 2

[0059] Comparative Example 2 provides a slurry for protecting the wall of diaphragm wall in pebble stratum.

[0060] The difference between the above examples and Example 3 is as follows: The addition amount of shell powder is 0.13 kg.

[0061] Comparative Example 3

[0062] Comparative Example 3 provides a slurry for protecting the wall of diaphragm wall in pebble stratum.

[0063] The difference between the above examples and Example 3 is as follows: Replace polypropylene fiber with sodium polyacrylate.

[0064] Performance detection test

[0065] The properties of the slurry for the diaphragm wall obtained in Examples 1-15 and Comparative Examples 1-3 were tested, including viscosity, specific gravity, filtration loss, and slump test. The results are shown in Table 3 below.

[0066] (1) Viscosity: The viscosity of the slurry for the diaphragm wall was measured using a "Coat-4 cup" viscometer.

[0067] (2) Specific gravity: The specific gravity of the slurry for the diaphragm wall was measured using a mud balance.

[0068] (3) Filtration loss: The filtration loss of the slurry refers to the amount of permeate passing through a 45.3 cm 5 filtration area within 30 minutes under a pressure of 6.867×10 2 Pa; it was measured using a ZNS-2A slurry filtration loss tester.

[0069] (4) Slump test: The slurry for the diaphragm wall obtained in Examples 1-15 and Comparative Examples 1-3 was used for the protection of the pebble stratum. Timing started after the slurry for the diaphragm wall was poured, and ended when the diaphragm wall collapsed. The protection time of each slurry for the diaphragm wall was tested.

[0070] Table 3 Test results of the properties of the slurry for the diaphragm wall obtained in Examples 1-15 and Comparative Examples 1-3

[0071]

[0072] According to the test results in Table 3, the viscosity of the slurry for the diaphragm wall obtained in Examples 1-15 of the present application was 20-25 S, the specific gravity was 1.02-1.14, and the filtration loss was 11-18 mL. The diaphragm wall would not collapse within 150 h after the above slurry for the diaphragm wall was used for the protection of the pebble stratum. The viscosity of the slurry for the diaphragm wall obtained in Comparative Example 1 was only 18 S, the specific gravity was 1.00, and the filtration loss was 20 mL. The diaphragm wall collapsed 96 h after the above slurry for the diaphragm wall was used for the protection of the pebble stratum. The viscosity of the slurry for the diaphragm wall obtained in Comparative Examples 2-3 was 27-30 S, the specific gravity was 1.15-1.17, and the filtration loss was 9-10 mL. When the above slurry for the diaphragm wall was used for the protection of the pebble stratum, it was found that the fluidity of the slurry was poor and the pouring was difficult. Therefore, it shows that the slurry for the diaphragm wall prepared from bentonite, cement, shell powder, etc. in the present application has excellent properties. When it is used for the protection of the complex pebble stratum, it can achieve a lasting and stable protection effect, providing safety guarantee for the long-time operation and construction of the diaphragm wall.

[0073] From the test results of Examples 1-5, it can be seen that the viscosity of the slurry for shaft wall obtained in Example 1 is 20S, and the filtration loss is 17 mL. The viscosity is on the low side and the filtration loss is too large. After using the above slurry for shaft wall protection in a cobble stratum, collapse occurred after 157 h. The viscosity of the slurry for shaft wall obtained in Example 5 is as high as 25S, and the specific gravity is as high as 1.12. The viscosity of the slurry for shaft wall is slightly high and the fluidity is slightly poor, making the pouring slightly difficult. However, the viscosity of the slurry for shaft wall obtained in Examples 2-4 is 22-23S, the specific gravity is 1.02-1.12, and the filtration loss is 15-16 mL. After using the above slurry for shaft wall protection in a cobble stratum, the shaft wall protection time is as long as 160-164 h. Therefore, it shows that when the addition amount of shell powder in this application is controlled within the range of 6.5-8.5 parts, the viscosity and filtration loss of the obtained slurry for shaft wall are moderate, the shaft wall protection time is long, and it can meet the use requirements of the diaphragm wall in a cobble stratum.

[0074] From the test results of Example 3 and Examples 6-9, it can be seen that as the addition amount of KH792-modified polypropylene fiber increases, the viscosity and specific gravity of the obtained slurry for shaft wall increase slightly, the filtration loss gradually decreases, and the shaft wall protection time first increases and then basically remains unchanged. Further comparison shows that the viscosity of the slurry for shaft wall obtained in Example 6 is 20S, the filtration loss is 18 mL, the viscosity is on the low side, the filtration loss is too large, and the shaft wall protection time is 158 h. However, the viscosity of the slurry for shaft wall obtained in Example 3 and Examples 7-9 is 22-23S, the specific gravity is 1.02-1.6, the filtration loss is 13-16 mL, and the shaft wall protection time is 161-165 h. Therefore, considering the comprehensive cost, in this application, the addition amount of KH792-modified polypropylene fiber is further controlled within the range of 1.5-2.5 parts. The viscosity and filtration loss of the obtained slurry for shaft wall are moderate, the shaft wall protection time is long, and it can meet the use requirements of the diaphragm wall in a cobble stratum.

[0075] From the test results of Example 3 and Examples 10 - 15, it can be seen that in Example 3, shell powder with a particle size of 800 - 1000 μm was used, and the wall protection time of the prepared slurry for protecting the wall was 163 h; in Example 10, shell powder with a particle size of 100 - 200 μm was used, and the wall protection time of the prepared slurry for protecting the wall was 170 h; in Example 14, a mixture of shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 500 - 600 μm was used to prepare the slurry for protecting the wall, and the wall protection time was 171 h; in Example 15, a mixture of shell powder with a particle size of 500 - 600 μm and shell powder with a particle size of 800 - 1000 μm was used to prepare the slurry for protecting the wall, and the wall protection time was 175 h; while in Examples 11 - 13, a mixture of shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm was used to prepare the slurry for protecting the wall, and the wall protection time was 180 - 183 h. Therefore, it shows that further using a mixture of shell powder with a particle size of 100 - 200 μm and shell powder with a particle size of 800 - 1000 μm to prepare the slurry for protecting the wall of the diaphragm wall in this application, the wall protection effect of the obtained slurry for protecting the wall is better, the stability of the trench wall is better, it can ensure no collapse within 180 h, and meet the requirements for the construction of the diaphragm wall for a long time.

[0076] Although the present invention has been described in detail with general descriptions and specific embodiments above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An underwater continuous wall protecting slurry for pebble stratum, characterized in that, It comprises the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 5 - 10 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1 - 3 parts of KH792 modified polypropylene fiber, and 450 - 500 parts of water; The shell powder includes shell powder with a particle size of 100 - 200 μm and shells with a particle size of 800 - 1000 μm; the weight ratio of the shell powder with a particle size of 100 - 200 μm to the shell powder with a particle size of 800 - 1000 μm is 1:(0.67 - 0.83); The preparation method of the KH792 modified polypropylene fiber is as follows: Immerse the polypropylene fiber in a 2wt% KH792 solution for 24 h, and the weight ratio of the polypropylene fiber to the KH792 solution is 1:6.5; then repeatedly wash the soaked polypropylene fiber with distilled water 3 times, and then place it in a drying chamber with a relative humidity of 50 ± 5% and dry it for 5 days until constant weight to obtain the KH792 modified polypropylene fiber.

2. The slurry for protecting the wall of the diaphragm wall in the pebble stratum according to claim 1, wherein, The slurry for protecting the wall of the diaphragm wall in pebble stratum comprises the following components in parts by weight: 30 - 50 parts of bentonite, 20 - 30 parts of cement, 6.5 - 8.5 parts of shell powder, 3 - 8 parts of carboxymethyl cellulose, 1.5 - 2.5 parts of KH792 modified polypropylene fiber, and 450 - 500 parts of water.

3. The slurry for protecting the wall of the diaphragm wall in pebble stratum according to claim 1, characterized in that The slurry for protecting the wall of the diaphragm wall in pebble stratum comprises the following components in parts by weight: 40 parts of bentonite, 25 parts of cement, 7.5 parts of shell powder, 5 parts of carboxymethyl cellulose, 2 parts of KH792 modified polypropylene fiber, and 480 parts of water.

4. The preparation method of the slurry for the diaphragm wall in pebble stratum according to any one of claims 1-3, characterized in that It includes the following steps: First, mix bentonite, shell powder with part of the water, stir evenly and let it stand for 8 - 10 h to obtain premix ①; Then mix cement, carboxymethyl cellulose, KH792 modified polypropylene fiber with the remaining water to obtain premix ②; Mix premix ① and premix ② evenly to obtain the slurry for protecting the wall of the diaphragm wall in pebble stratum.

5. The preparation method of the slurry for the diaphragm wall in pebble stratum according to claim 4, characterized in that, The temperature of the standing is 35 - 45 °C.

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