Wall protection slurry for underground diaphragm wall in pebble stratum and preparation method of wall protection slurry

Abstract

The invention relates to the technical field of underground engineering construction, and particularly discloses pebble stratum underground diaphragm wall protecting slurry and a preparation method thereof. The pebble stratum underground diaphragm wall protecting slurry provided by the invention is prepared from the following components in parts by weight: 30 to 50 parts of bentonite, 20 to 30 parts of cement, 5 to 10 parts of shell powder, 3 to 8 parts of carboxymethyl cellulose, 1 to 3 parts of KH792 modified polypropylene fiber and 450 to 500 parts of water, further, the shell powder comprises shell powder with the particle size of 100-200 [mu] m and shell powder with the particle size of 800-1000 [mu] m; the invention further provides a preparation method of the pebble stratum underground diaphragm wall protecting slurry. The pebble stratum underground diaphragm wall protecting slurry provided by the invention is low in cost and good in protecting effect, a formed groove wall is excellent in stability, and the pebble stratum underground diaphragm wall protecting slurry can be prevented from collapsing for 120 hours and can meet the construction requirements of an underground diaphragm wall.

Description

Technical Field

[0001] The present application relates to the technical field of underground engineering construction, and in particular to a slurry for underground continuous wall protection in a pebble stratum and a preparation method thereof. Background Art

[0002] In construction projects, especially in underground continuous wall construction, the performance of the wall slurry directly affects the stability and construction quality of the wall. With the accelerated development of urban construction, pebble strata, as a common geological condition, put forward higher requirements for the construction of underground continuous walls. Reasonable configuration of wall slurry can not only effectively prevent wall collapse, but also improve construction efficiency, reduce costs, and ensure the smooth progress of the project.

[0003] At present, there are three main formulas used for the preparation of wall protection mud for underground continuous wall construction in pebble strata: one is based on bentonite as the main ingredient, and the rheological properties of the mud are adjusted by adding an appropriate amount of viscosity enhancer or thickener; the other is based on a mixture of bentonite and cement, and the wall fixing performance and sedimentation stability of the mud are improved by adjusting the ratio of the two and adding other chemical additives; and there is another type that uses a mixture of multiple mineral powders, such as kaolin, fly ash, etc., combined with bentonite to enhance the adaptability of the mud in complex strata.

[0004] However, these conventional formulas have many shortcomings in the actual application of pebble strata. Due to the complex structure of the pebble strata, large spacing between stones, and easy water seepage, the trench 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 underground continuous wall. Summary of the invention

[0005] In order to improve the wall protection performance and trench wall stability of the wall protection slurry, the present application provides a pebble formation underground continuous wall protection slurry and a preparation method.

[0006] In the first aspect, the present application provides a slurry for underground continuous wall protection in pebble formations, adopting the following technical scheme: a slurry for underground continuous wall protection in pebble formations, 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] The present application adopts bentonite, cement, shell powder, etc. to prepare a kind of underground continuous wall retaining mud with excellent stability and good anti-seepage performance in pebble strata. By controlling the weight of each component within the above range, the retaining mud can not only effectively prevent groundwater infiltration in the pebble strata, but also adapt to the complex geological conditions of the pebble strata, significantly improve the wall protection effect during the construction of the underground continuous wall, so that the trench wall does not collapse for up to 150 hours, meeting the requirements of the long-term construction of the underground continuous wall; and the retaining mud has good fluidity, which can greatly reduce the difficulty of construction. In addition, the raw materials used in the retaining mud of the present application have good economic and environmental protection characteristics, which is conducive to controlling construction costs while reducing environmental impact. In summary, the new type of retaining mud provided by the present application can realize efficient and safe construction of underground continuous walls under the premise of ensuring the quality of the project.

[0008] Optionally, the pebble stratum underground continuous wall slurry 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, and 1.5-2.5 parts of KH792 modified polypropylene fiber. And 450-500 parts of water.

[0009] Optionally, the pebble formation underground continuous wall retaining mud 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.

[0010] In some embodiments, the weight portions 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.

[0011] In a specific embodiment, the weight proportion of the shell powder can also be 5 parts, 6.5 parts, 7.5 parts, 8.5 parts or 10 parts.

[0012] In some embodiments, the weight proportion of the KH792 modified polypropylene fiber may be 1-1.5, 1-2, 1-2.5, 1-3, 1.5-2, 1.5-2.5, 1.5-3, 2-2.5, 2-3 or 2.5-3.

[0013] In a specific embodiment, the weight proportion of the KH792 modified polypropylene fiber can also be 1 part, 1.5 parts, 2 parts, 2.5 parts or 3 parts.

[0014] 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.

[0015] In some embodiments, the shell powder can 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.

[0016] 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).

[0017] In this application, it was found through experimental research that the further use of shell powder with the above-mentioned particle size ratio can obtain a wall protection mud with better comprehensive performance in viscosity, specific gravity and filtration loss, which can better meet the use requirements of underground continuous walls in pebble formations.

[0018] 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).

[0019] 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.

[0020] Optionally, the preparation method of the KH792 modified polypropylene fiber comprises the following steps: soaking the polypropylene fiber in a 2wt% KH792 solution for 24 hours, with the weight ratio of the polypropylene fiber to the KH792 solution being 1:6.5; then repeatedly washing the soaked polypropylene fiber with distilled water for 3 times, and then placing it in a drying room with a relative humidity of 50±5% and drying it for 5 days to constant weight to obtain the KH792 modified polypropylene fiber.

[0021] In the present application, polypropylene fiber is non-polar and therefore hydrophobic. When it is directly used in the wall protection slurry, its dispersibility and fluidity are slightly poor and it is prone to agglomeration. The present application further modifies the polypropylene fiber to obtain KH792 modified polypropylene fiber, which can increase the fluidity and toughness of the wall protection slurry, thereby greatly improving the crack resistance of the wall protection slurry and effectively avoiding the collapse of the trench wall.

[0022] In a second aspect, the present application provides a method for preparing a slurry for an underground continuous wall in a pebble formation, comprising the following steps: First, mix bentonite, shell powder and part of water, stir evenly and let stand for 8-10 hours to obtain premix①; Then, cement, carboxymethyl cellulose, polypropylene fiber and remaining water are mixed to obtain a premix②; The premix ① and the premix ② are mixed evenly to obtain the pebble stratum underground continuous wall retaining slurry.

[0023] Optionally, the standing temperature is 35-45°C.

[0024] In summary, this application has the following beneficial effects: 1. This application uses bentonite, cement, shell powder, etc. to prepare a wall protection mud, which has good stability and anti-permeability, can significantly improve the wall protection effect during the construction of underground continuous walls, and prevent the trench wall from collapsing for up to 150 hours, meeting the requirements for long-term construction of underground continuous walls in pebble formations.

[0025] 2. The present application further adopts shell powder with a particle size of 100-200μm and shell powder with a particle size of 800-1000μm to prepare wall protection mud, and the weight ratio of the above-mentioned particle size shell powder is controlled within the range of 1:(0.67-0.83). The obtained wall protection mud has better comprehensive properties such as viscosity and filtration loss, and the injection mobile phase is excellent. When used for pebble formation wall protection, it can ensure that no collapse occurs within 180 hours, and can better meet the use requirements of long-term construction operations of underground continuous walls in pebble formations. DETAILED DESCRIPTION

[0026] The present application provides a pebble stratum underground continuous wall retaining slurry, 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. Further, the pebble stratum underground continuous wall retaining slurry 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.

[0027] 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. Furthermore, 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).

[0028] The present application provides a method for preparing a pebble stratum underground continuous wall slurry, comprising the following steps: (1) First, bentonite, shell powder and water accounting for 2 / 3 of the total amount are mixed, stirred evenly and allowed to stand at 35-45° C. for 8-10 hours to obtain a premix ①; (2) Mixing cement, carboxymethyl cellulose, KH792 modified polypropylene fiber and remaining water to obtain a premix ②; (3) Premix ① and premix ② are mixed evenly to obtain a slurry for underground continuous wall protection in pebble formation.

[0029] In this application, bentonite was purchased from Lingshou County Zexu Mineral Products Trading Co., Ltd.; cement was P.W42.5 silicate cement; shell powder was obtained by crushing clam shells; carboxymethyl cellulose was purchased from Zibo Daoqin New Materials Co., Ltd.; polypropylene fiber was purchased from Tai'an Anfeng New Materials Technology Co., Ltd. The remaining raw materials, reagents, solvents, etc. of this application can be obtained through commercial purchase.

[0030] The present application is further described in detail below in combination with preparation examples, embodiments and performance testing experiments.

[0031] Examples 1-9 Examples 1-9 respectively provide a kind of underground continuous wall protection mud for pebble formation.

[0032] The difference between the above embodiments is that the addition amounts of shell powder and polypropylene fiber in the wall protection mud are specifically shown in Table 1 below.

[0033] The method for preparing the slurry for underground continuous wall in pebble formation provided in Examples 1-9 comprises the following steps: (1) First, 4 kg of bentonite, shell powder (particle size of 800-1000 μm) and 32 kg of water were mixed, stirred evenly and allowed to stand at 35-45° C. for 8-10 hours to obtain a premix ①; (2) Mix 2 kg of cement, 0.5 kg of carboxymethyl cellulose, KH792 modified polypropylene fiber and 16 kg of water to obtain a premix ②; (3) Premix ① and premix ② are mixed evenly to obtain a slurry for underground continuous wall protection in pebble formation.

[0034] Among them, the preparation method of KH792 modified polypropylene fiber is: immerse the polypropylene fiber in a 2wt% KH792 solution for 24 hours, and the weight ratio of the polypropylene fiber to the KH792 solution is 1:6.5; then the immersed polypropylene fiber is repeatedly washed 3 times with distilled water, and then placed in a drying room with a relative humidity of 50±5% and dried for 5 days to constant weight to obtain KH792 modified polypropylene fiber.

[0035] Table 1 Addition amount of shell powder and KH792 modified polypropylene fiber in the wall protection mud of Examples 1-9 Examples 10-15 Examples 10-15 respectively provide a kind of underground continuous wall protection mud for pebble formation.

[0036] The difference between the above embodiment and embodiment 3 is that the particle size and proportion of shell powder are specifically shown in Table 2 below.

[0037] Table 2 Particle size and ratio of shell powder in Example 3 and Examples 10-15 Comparative Example 1 Comparative Example 1 provides a kind of underground continuous wall protection slurry for pebble stratum.

[0038] The difference between the above embodiment and embodiment 3 is that the shell powder is replaced with 1250 mesh barite powder.

[0039] Comparative Example 2 Comparative Example 2 provides a kind of underground continuous wall protection mud in pebble stratum.

[0040] The difference between the above embodiment and embodiment 3 is that the added amount of shell powder is 0.13 kg.

[0041] Comparative Example 3 Comparative Example 3 provides a kind of underground continuous wall protection mud in pebble stratum.

[0042] The difference between the above embodiment and embodiment 3 is that the polypropylene fiber is replaced by sodium polyacrylate.

[0043] Performance testing Various properties of the underground continuous wall retaining slurry obtained in Examples 1-15 and Comparative Examples 1-3 were tested, including viscosity, specific gravity, filtration loss and collapse tests. The results are shown in Table 3 below.

[0044] (1) Viscosity: The viscosity of the wall protection mud was tested using a "Tu-4 cup" viscosity tester.

[0045] (2) Specific gravity: Use a mud density meter to measure the specific gravity of the wall protection mud.

[0046] (3) Filtration loss: Mud filtration loss refers to the amount of slurry lost at 6.867×10 5 Under the pressure of Pa, the mud passes 45.3cm in 30 minutes. 2 The amount of permeate in the filtration area is tested using the ZNS-2A mud loss tester.

[0047] (4) Collapse test: The underground continuous wall protection mud obtained in Examples 1-15 and Comparative Examples 1-3 was used for the protection of the gravel stratum wall. The timing started from the completion of the injection of the protection mud and ended when the protection wall collapsed. The protection time of each protection mud was tested.

[0048] Table 3 Test results of various properties of underground continuous wall slurry obtained in Examples 1-15 and Comparative Examples 1-3 According to the test results in Table 3, the wall protection mud obtained in Examples 1-15 of the present application has a viscosity of 20-25S, a specific gravity of 1.02-1.14, and a filtration loss of 11-18mL. The wall protection mud will not collapse within 150 hours after being used for wall protection in pebble formations. The wall protection mud obtained in Comparative Example 1 has a viscosity of only 18S, a specific gravity of 1.00, and a filtration loss of 20mL. The wall protection mud collapsed 96 hours after being used for wall protection in pebble formations; the wall protection mud obtained in Comparative Examples 2-3 has a viscosity of 27-30S, a specific gravity of 1.15-1.17, and a filtration loss of 9-10mL. When the wall protection mud was used for wall protection in pebble formations, it was found that the mud had poor fluidity and was difficult to inject. Therefore, it is explained that the wall protection mud prepared by bentonite, cement, shell powder, etc. in this application has excellent properties. It is used for complex pebble stratum wall protection to achieve a long-lasting and stable wall protection effect and provide safety guarantee for the long-term construction of underground continuous walls.

[0049] From the test results of Examples 1-5, it can be seen that the viscosity of the wall protection mud obtained in Example 1 is 20S, and the filtration loss is 17mL. The viscosity is low and the filtration loss is too large. The above-mentioned wall protection mud was used for the pebble formation wall protection for 157h and collapsed; the viscosity of the wall protection mud obtained in Example 5 is as high as 25S, and the specific gravity is as high as 1.12. The viscosity of the wall protection mud is slightly large, the fluidity is slightly poor, and the perfusion is slightly difficult. The viscosity of the wall protection mud obtained in Examples 2-4 is 22-23S, the specific gravity is 1.02-1.12, and the filtration loss is 15-16mL. After the above-mentioned wall protection mud is used for the pebble formation wall protection, the wall protection time is as long as 160-164h. Therefore, it is explained that the application controls the addition amount of shell powder within the range of 6.5-8.5 parts, and the viscosity and filtration loss of the obtained wall protection mud are moderate, the wall protection time is long, and it can meet the use requirements of the underground continuous wall of the pebble formation.

[0050] The test results of Example 3 and Examples 6-9 show that with the increase in the amount of KH792 modified polypropylene fiber added, the viscosity and specific gravity of the obtained wall protection mud slightly increase, the filtration loss gradually decreases, and the wall protection time first increases and then remains basically unchanged. Further comparison shows that the viscosity of the wall protection mud obtained in Example 6 is 20S, the filtration loss is 18mL, the viscosity is low, the filtration loss is too large, and the wall protection time is 158h; while the viscosity of the wall protection mud obtained in Example 3 and Examples 7-9 is 22-23S, the specific gravity is 1.02-1.6, the filtration loss is 13-16mL, and the wall protection time is 161-165h. Therefore, considering the comprehensive cost, the application further controls the addition amount of KH792 modified polypropylene fiber within the range of 1.5-2.5 parts, and the obtained wall protection mud has moderate viscosity and filtration loss, and a long wall protection time, which can meet the use requirements of underground continuous walls in pebble formations.

[0051] From the test results of Example 3 and Examples 10-15, it can be seen that Example 3 uses shell powder with a particle size of 800-1000μm, and the wall protection time of the wall protection mud prepared is 163h; Example 10 uses shell powder with a particle size of 100-200μm to prepare the wall protection mud, and the wall protection time is 170h; Example 14 uses a mixture of 100-200μm shell powder and 500-600μm shell powder to prepare the wall protection mud, and the wall protection time is 171h; Example 15 uses a mixture of 500-600μm shell powder and 800-1000μm shell powder to prepare the wall protection mud, and the wall protection time is 175h; and Examples 11-13 use a mixture of 100-200μm shell powder and 800-1000μm shell powder to prepare the wall protection mud, and the wall protection time is 180-183h. Therefore, it is explained that the present application further adopts a mixture of 100-200μm shell powder and 800-1000μm shell powder to prepare underground continuous wall protective mud. The obtained wall protective mud has better wall protective effect and better trench wall stability, which can ensure that it will not collapse within 180 hours and meet the requirements of longer-term construction of underground continuous walls.

[0052] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. A slurry for underground continuous wall protection in pebble strata, characterized in that: The invention 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.

2. The pebble stratum underground continuous wall protection slurry according to claim 1, characterized in that: The pebble stratum underground continuous wall protection slurry 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 underground continuous wall protection in pebble strata according to claim 1, characterized in that: The pebble stratum underground continuous wall protection slurry 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 slurry for underground continuous wall protection in pebble strata according to claim 1, characterized in that: 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.

5. The slurry for underground continuous wall protection in pebble strata according to claim 4, characterized in that: 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).

6. The slurry for underground continuous wall protection in pebble strata according to claim 1, characterized in that: The preparation method of the KH792 modified polypropylene fiber is as follows: the polypropylene fiber is immersed in a 2wt% KH792 solution for 24 hours, and the weight ratio of the polypropylene fiber to the KH792 solution is 1:6.5; then the immersed polypropylene fiber is repeatedly washed 3 times with distilled water, and then placed in a drying room with a relative humidity of 50±5% and dried for 5 days to constant weight to obtain the KH792 modified polypropylene fiber.

7. The method for preparing the slurry for underground continuous wall in pebble strata according to any one of claims 1 to 6, characterized in that: The following steps are involved: First, mix bentonite, shell powder and part of water, stir evenly and let stand for 8-10 hours to obtain premix①; Then, cement, carboxymethyl cellulose, KH792 modified polypropylene fiber and remaining water are mixed to obtain premix②; The premix ① and the premix ② are mixed evenly to obtain the pebble stratum underground continuous wall retaining slurry.

8. The method for preparing the slurry for underground continuous wall in pebble stratum according to claim 7, characterized in that: The standing temperature is 35-45°C.

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