Water-rich round gravel stratum diaphragm wall construction cement paste composition, preparation method and application
By using compound cement slurry compositions and sawdust in the construction of water-rich gravel formation ground connection walls, the problems of high mud loss rate and poor wall protection performance are solved, and a more stable groove wall structure is achieved.
Patent Information
- Application Number
- CN202411875243.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-19
- Publication Date
- 2025-03-21
AI Technical Summary
During the process of ground connection walls forming troughs in water-rich gravel formations, the mud loss rate is high, resulting in poor wall protection performance and partial collapse of the trough wall.
A water-rich round gravel formation ground-connected wall construction cement slurry composition is employed, which includes bentonite, soda ash, CMC, lightly burned magnesium, binder and sawdust to increase the viscosity, specific gravity and stability of the slurry by compounding, and to block mud loss through sawdust.
It significantly reduces the mud loss rate, improves the wall protection performance and stability of the groove wall, and avoids local collapse of the groove wall.
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Figure CN119661172A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of ground-anchored wall construction, and particularly relates to a cement slurry composition for ground-anchored wall construction in a water-rich gravel stratum, a preparation method and an application thereof. Background Art
[0002] The underground continuous wall was proposed as a patent abroad as early as 1920, and it has a history of nearly 100 years. The application of underground continuous wall construction technology in actual engineering has a history of nearly 50 years. During the construction of subway stations, deep foundation pits need to be excavated. In order to avoid the collapse and deformation of the surrounding soil during the excavation of the foundation pit, an underground continuous wall will be pre-built outside the foundation pit. The underground continuous wall is to use trenching machinery on the ground, along the peripheral axis of the deep excavation project, under the condition of mud wall protection, to excavate a long and narrow deep trench. After cleaning the trench, a steel cage is suspended in the trench, and then underwater concrete is poured into a unit trench section by the conduit method. This is done section by section to build a continuous reinforced concrete wall underground as a water interception, anti-seepage, load-bearing, and water-retaining structure.
[0003] For areas where the gravel layer contains confined water and the confined water is mobile, the mud loss rate is as high as 3m during the trenching process of the ground-connected wall. 3 / h. The flowing groundwater dilutes and carries away the mud, reducing the wall protection performance of the mud and the self-stabilizing ability of the gravel layer, causing partial collapse of the trench wall during the trenching process. Summary of the invention
[0004] The purpose of the present invention is to overcome the technical defects in the prior art of high mud loss rate during trenching of ground-connected walls in water-rich gravel formation structures, which reduces the wall protection performance of the mud, and to provide a cement slurry composition, preparation method and application for ground-connected walls in water-rich gravel formations.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] A cement slurry composition for ground-connected wall construction in water-rich gravel strata, comprising the following raw materials in parts by weight per cubic meter:
[0007] 170-200 parts of bentonite, 8-15 parts of soda ash, 4-8 parts of CMC, 1-2.5 parts of light-burned magnesia, 1-2 parts of adhesive, 900-1000 parts of water; also includes sawdust, the weight percentage of the sawdust in the cement slurry composition is in the range of 4-8%.
[0008] In the technical solution of the present invention, in order to overcome the technical defects of high mud loss rate and poor wall protection performance during the trenching process of the ground-connected wall in the water-rich gravel stratum structure, the mud used for the ground-connected wall construction is compounded. On the basis of the base material bentonite, soda ash, CMC, light-burned magnesium and adhesive additives for improving the overall viscosity of the mud composition are added to further increase the viscosity, specific gravity and stability of the mud, thereby improving the wall protection effect. Soda ash can reduce water loss, increase stability, static shear force and pH value; CMC can reduce water loss, increase stability and static shear force; light-burned magnesium can increase the viscosity and stability of the slurry; and the adhesive can increase the viscosity of the slurry. On the basis of the above-mentioned compound composition, 4-6% by weight of sawdust components are further added. The sawdust is suspended and distributed in the mud through the mud circulation. When the mud diffuses and loses, the sawdust is taken away and filled in the gaps of the groove wall, thereby preventing the loss of mud.
[0009] As a preferred embodiment of the present invention, the following ingredients are used: 180-190 parts of bentonite, 10-13 parts of soda ash, 5-7 parts of CMC, 1-2 parts of light-burned magnesia, 1.2-1.6 parts of binder, and 950-980 parts of water.
[0010] Carboxymethyl cellulose (CMC) is the largest, most widely used and most convenient product among cellulose ethers, commonly known as "industrial MSG". Mud containing CMC can form a thin and hard filter cake with low permeability on the well wall, reducing water loss.
[0011] After adding CMC to the mud, the drilling rig can obtain a low initial shear force, making it easy for the mud to release the gas wrapped in it, and at the same time quickly abandon the debris in the mud pit. Drilling mud, like other suspended dispersions, has a certain existence period. After adding CMC, it can be stabilized and the existence period can be extended. Mud containing CMC is rarely affected by mold, so it is not necessary to maintain a very high pH value or use preservatives. CMC is used as a drilling mud washing fluid treatment agent to resist pollution from various soluble salts. Mud containing CMC has good stability and can reduce water loss even at temperatures above 150°C. CMC with high viscosity and high degree of substitution is suitable for mud with low density, while CMC with low viscosity and high degree of substitution is suitable for mud with high density.
[0012] The soda ash is anhydrous sodium carbonate, which has the general properties of salt and belongs to inorganic salt. The pH value of the composition can be adjusted by compounding it in the mud composition. The soda ash and CMC can cooperate synergistically to reduce the overall water loss of the mud composition, and significantly improve the stability and static shear force.
[0013] Light-burned magnesium is made by calcining magnesite, brucite and magnesium hydroxide extracted from seawater or brine at about 800-1000℃ to decompose and emit CO 2 or H 2O, that is, light-burned magnesium powder is obtained, also known as light-burned magnesium oxide, caustic magnesium oxide or light-burned magnesium, commonly known as magnesia powder. Light-burned magnesium reacts with water to produce Mg(OH) 2 Hardening can improve the overall bonding ability of the mud composition.
[0014] As a preferred embodiment of the present invention, the weight percentage of sawdust is 5-6%. The higher the sawdust content, the less the mud loss is, and the more conducive it is to preventing the mud from seeping. However, the effect of reducing mud loss is not obvious after the content exceeds 6%. Too much sawdust is not easy to stir evenly during stirring, which is not conducive to the control of the slurry, and it is easy to clog during the mud circulation process, which is not conducive to troughing. Sawdust can effectively reduce mud loss, and the optimal content is about 5-6%.
[0015] Sawdust is also called sawdust, which is powdery wood chips of trees scattered from trees during sawing. Preferably, in the present invention, the raw material of sawdust is at least one of oak, pine and birch.
[0016] As a preferred embodiment of the present invention, the particle size of the sawdust is any one of 6 mesh and 10 mesh.
[0017] As a preferred embodiment of the present invention, the bentonite adopts Weifang bentonite. In the technical scheme of the present invention, a large number of experimental studies have been conducted on the performance of bentonites from different origins, and it is found that the viscosity of Anji bentonite slurry is between 35 and 40 seconds when the specific gravity is 1.12 to 1.15, and the viscosity of Weifang bentonite slurry is between 41 and 46 seconds when the specific gravity is 1.12 to 1.15. Therefore, this scheme preferably uses Weifang bentonite as the mud base material.
[0018] As a preferred embodiment of the present invention, the following ingredients are used: 186 parts of bentonite, 11.6 parts of soda ash, 5.58 parts of CMC, 1.49 parts of light-burned magnesia, 1.4 parts of adhesive, and 955 parts of water; the weight percentage of the sawdust is 5%.
[0019] A method for preparing a cement slurry composition according to any one of claims 1 to 5, characterized in that it comprises the following steps:
[0020] S1, mixing bentonite and water in proportion, and stirring evenly to obtain a first mixed solution;
[0021] S2, adding soda ash, CMC, light-burned magnesium and a binder into water in proportion, and stirring evenly to obtain a second mixed solution;
[0022] S3, mixing the first mixed liquid and the second mixed liquid, and then mixing sawdust into the mixed liquid according to a certain proportion and stirring evenly to obtain a cement slurry composition.
[0023] As a preferred embodiment of the present invention, the preparation method also includes S4, performing a performance test on the cement slurry composition: preparing experimental instruments according to the target performance indicators, and then swelling the prepared cement slurry composition for at least 24 hours to form a mud sample, and testing the performance of the mud sample by using the corresponding experimental instruments. When the mud sample has indicators that do not meet the standards, the proportions are corrected again according to steps S1-S3 to obtain a cement slurry composition that meets the standards.
[0024] Preferably, the performance indicators include viscosity, specific gravity, pH value, colloid rate, stability and mud skin thickness.
[0025] Specifically, mud stability refers to whether the mud is easy to sink under the action of geocentric stress. The "water separation test" and "upper and lower specific gravity difference test" are commonly used to measure mud stability. For mud that has been left to stand for more than 1 hour, take mud samples from the upper 1 / 3 and lower 1 / 3 of its container and measure their densities respectively. If there is no difference between the two, the mud quality is qualified.
[0026] An application of a cement slurry composition, characterized in that the cement slurry composition is used for the construction of ground-connected walls in water-rich gravel strata.
[0027] Compared with the prior art, the present invention has the following beneficial effects:
[0028] The cement slurry composition of the present invention is compounded with soda ash, CMC, light-burned magnesium and adhesive auxiliary materials on the basis of the base material bentonite, so as to further increase the viscosity, specific gravity and stability of the mud, thereby improving the wall protection effect. Furthermore, on the basis of the above-mentioned compound composition, 5% by weight of sawdust components are further added, and the sawdust is suspended and distributed in the mud through the mud circulation, and the sawdust is taken away and filled in the gaps of the tank wall while the mud diffuses and loses, thereby preventing the loss of mud. BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Figure 1 A geological profile of the area to be constructed;
[0030] Figure 2 It is the test record diagram of the first and second order test slots;
[0031] Figure 3 The following are the test results of the test tank after 8h and 16h of trough formation. DETAILED DESCRIPTION
[0032] The present invention is further described in detail below in conjunction with test examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the content of the present invention belong to the scope of the present invention.
[0033] Unless otherwise specified, in the description of the specific embodiments of the present invention, the terms indicating the orientation or position relationship such as "up", "down", "left", "right", "center", "inside", "outside", etc. are all expressions based on the orientation or position relationship shown in the drawings, or the orientation or position relationship when the invented product / equipment / device is usually used. These terms of orientation or position relationship are only for the convenience of describing the scheme of the present invention or simplifying the description in the specific embodiments, so as to facilitate the technicians to quickly understand the scheme, rather than indicating or implying that a specific device / component / element must have a specific orientation, or be constructed and operated in a specific position relationship, and therefore cannot be understood as a limitation on the present invention.
[0034] In addition, if the terms "horizontal", "vertical", "overhanging", "parallel" and the like appear, it does not mean that the corresponding devices / components / elements are required to be absolutely horizontal or vertical or overhanging or parallel, but may be slightly tilted or have deviations. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but may be slightly tilted. Alternatively, it can be simplified to mean that the corresponding devices / components / elements are set in directions such as "horizontal", "vertical", "overhanging", "parallel", etc., and can have an error / deviation of ±10% relative to the corresponding direction setting, more preferably an error / deviation within ±8%, more preferably an error / deviation within ±6%, more preferably an error / deviation within ±5%, and more preferably an error / deviation within ±4%. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its role in the scheme of the present invention.
[0035] In addition, the expressions “first”, “second”, “third”, etc. that appear in the terms are merely descriptions used to distinguish the same or similar components and should not be understood as emphasizing or implying the relative importance of specific components.
[0036] In addition, in the description of the embodiments of the present invention, "several", "plurality" and "a number" represent at least 2. It can be any number such as 2, 3, 4, 5, 6, 7, 8, 9, and even more than 9.
[0037] In addition, in the description of the technical solution of the present invention, unless otherwise clearly specified / defined / restricted, the terms "set", "install", "connect", "connected", "provided with", "laid", and "arranged" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection, and can be welding, riveting, bolting, threading, and other commonly used connection means in the field. This connection can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be the internal connection of two elements.
[0038] The composition and mix ratio of the cement slurry composition of the present invention are obtained based on the foundation soil composition of a subway project. Specifically, the proposed construction site is located in the plain area of northern Zhejiang. The Quaternary strata are developed within the exploration depth range, and there are many types of genesis, mainly lake silt soil and lake gravel, which are revealed to be about 8.7 to 31.9 meters thick through exploration.
[0039] Specifically, the rock and soil composition, stratigraphic age, thickness and elevation within the survey depth and range are shown in Table 1 below, and the geological profile is shown in Figure 1 As shown:
[0040] Table 1 is the classification table of foundation soil layers
[0041]
[0042] According to the groundwater-bearing space medium and water physics, hydrodynamic characteristics and occurrence conditions, the groundwater in the proposed site can be divided into Quaternary loose rock pore groundwater, pore pressure water and bedrock fissure water.
[0043] In this embodiment, in order to solve the problem of trenching collapse in the upper water-rich gravel layer, trial trenching was carried out by trial mixing different mud parameters, and the trenching effects were compared. The effects of different mud gravities, viscosities, and mud skin thicknesses on the wall protection effect were studied and compared, and the most suitable mud parameters for trenching in water-rich loose gravel formations in northern Zhejiang were found.
[0044] Table 2 shows the performance indexes of cement slurry compositions
[0045]
[0046] By trying to use bentonite from different origins to adapt the mud to the trial trench, the mud index performance was tested, and the mud parameters of Anji bentonite and Weifang bentonite and their effects on the stability of the trench wall were studied and compared; by trying to add different admixtures to configure the mud, the mud parameters were tested, and the effects of the dosage of admixtures such as soda ash and CMC on the wall protection effect were studied and compared; and an attempt was made to add sawdust to the wall protection mud to study whether the addition of sawdust to the wall protection mud could effectively reduce the loss of mud in water-rich formations, and the optimal dosage of sawdust.
[0047] In order to determine the influence of each raw material on the mud performance, single factor experiments were carried out on bentonite content, soda ash content, hydroxymethyl cellulose (PMC) content, and light-burned magnesium content, and finally the optimal cement slurry composition ratio under the construction environment of the present invention was determined.
[0048] The new slurry parameters were compared by the origin of bentonite, as shown in Table 3:
[0049] Table 3 is a comparison of bentonite pulping parameters from different origins
[0050]
[0051] By comparing the parameters of new slurry made from bentonite from different origins, it was found that the viscosity of Anji bentonite slurry was between 35 and 40s when the specific gravity was 1.12-1.15, and the viscosity of Weifang bentonite slurry was between 41 and 46s when the specific gravity was 1.12-1.15. This proves that the viscosity of Weifang bentonite is significantly stronger than that of Anji bentonite, and is more conducive to the stability of the trench wall.
[0052] Furthermore, in order to verify the actual wall protection performance difference between Weifang bentonite slurry and Anji bentonite slurry, trial trenching was carried out again in the vicinity outside the pit to ensure that there was no significant change in the geological conditions in the trenching area. The quality of the trench wall was tested by an ultrasonic wall measuring instrument and compared with the quality of the trench wall of the Anji bentonite trench. After trenching, the stability of the trench wall was tested again by ultrasonic wave every 8 hours and compared with the time of trenching to confirm the effect of waiting time on the stability of the trench wall and the durability of the mud wall protection. The test results of the trench wall of the trial trenching outside the pit are as follows: Figure 2-3 As shown, Figure 2 It is the test record diagram of the first and second order test slots; Figure 3 The following are the test results of the test tank after 8h and 16h of trough formation.
[0053] In the initial trenching process, two trenching trials using Anji bentonite failed (the maximum width of the trench wall collapse was about 1.5m). After the adjustment to Shandong Weifang bentonite, there was no trench wall collapse and the maximum local collapse width was 25cm, which fully demonstrated that the wall protection effect of Weifang bentonite is significantly better than that of Anji bentonite. When trenching in strata with poor geological conditions, especially in gravel layers, Weifang bentonite should be used as the material for the wall protection mud, which is conducive to the stability of the trench wall.
[0054] Example 1
[0055] 170 kg of bentonite and 980 kg of water were mixed in proportion and stirred to obtain a first mixed solution; 8 kg of soda ash, 4.23 kg of CMC, 1 kg of light-burned magnesia and 1 kg of adhesive were added into water and stirred to obtain a second mixed solution; the first mixed solution and the second mixed solution were mixed, and 5% by weight (58.2 kg) of sawdust was added thereto and stirred to obtain a cement slurry composition.
[0056] Example 2
[0057] 178 kg of bentonite and 900 kg of water are mixed in proportion and stirred to obtain a first mixed liquid; 8.5 kg of soda ash, 5 kg of CMC, 1.5 kg of light-burned magnesia and 1.2 kg of adhesive are added into water and stirred to obtain a second mixed liquid; the first mixed liquid and the second mixed liquid are mixed, and 4% by weight (43.7 kg) of sawdust is added thereto and stirred to obtain a cement slurry composition.
[0058] Example 3
[0059] 186 kg of bentonite and 960 kg of water were mixed in proportion and stirred to obtain a first mixed solution; 9.2 kg of soda ash, 6 kg of CMC, 2 kg of light-burned magnesia and 1.4 kg of adhesive were added into water and stirred to obtain a second mixed solution; the first mixed solution and the second mixed solution were mixed, and 5.5% by weight (64 kg) of sawdust was added thereto and stirred to obtain a cement slurry composition.
[0060] Example 4
[0061] 190 kg of bentonite and 1000 kg of water are mixed in proportion, and stirred evenly to obtain a first mixed liquid; 10.1 kg of soda ash, 8 kg of CMC, 2.5 kg of light-burned magnesia and 2 kg of adhesive are added into water, and stirred evenly to obtain a second mixed liquid; the first mixed liquid and the second mixed liquid are mixed, and 6% by weight (69.6 kg) of sawdust is mixed therein according to proportion and stirred evenly to obtain a cement slurry composition.
[0062] Example 5
[0063] 186 kg of bentonite and 955 kg of water were mixed in proportion and stirred to obtain a first mixed solution; 11.16 kg of soda ash, 5.58 kg of CMC, 1.49 kg of light-burned magnesia and 1.5 kg of adhesive were added into water and stirred to obtain a second mixed solution; the first mixed solution and the second mixed solution were mixed, and 5% by weight (60.6 kg) of sawdust was added thereto and stirred to obtain a cement slurry composition.
[0064] Comparative Example 1
[0065] A cement slurry composition was prepared in the comparative example. The preparation method and content of the cement slurry composition were the same as those of Example 5, except that the comparative example did not contain sawdust.
[0066] Comparative Example 2
[0067] A cement slurry composition was prepared in the comparative example. Its preparation method and content were the same as those in Example 5, except that the amount of sawdust added in the comparative example was 3%.
[0068] The slurry loss of the cement slurry mixtures of Examples 1-5 and Comparative Examples 1-2 at different sawdust dosages is shown in the following table:
[0069] Table 4 is a comparison of mud loss after sawdust addition
[0070]
[0071] The mud performance test was carried out on Examples 1-5 and Comparative Examples 1-2. The results are shown in Table 5:
[0072] Specifically, the test method for specific gravity is as follows: inject the mud sample into the mud cup, flush the cup mouth, drain the excess mud and air, slowly move the weight on the scale, when the bubble is in the center and the lever is horizontal, the scale value is the specific gravity, the unit is (g / cm 3 ).
[0073] The viscosity test method is the funnel method. Use your finger to block the outflow port at the bottom of the funnel, inject the mud sample into the funnel through the screen until the liquid level reaches the bottom of the screen, remove your finger and start the stopwatch. The time required for the sample to flow to the 1500mL mark in the measuring cup is the funnel viscosity, in (s).
[0074] pH value: Dip the mud filtrate that has passed the water loss meter test and drop it in the middle of the pH test paper. Compare the stabilized color with the standard colorimetric card to get the pH value.
[0075] A certain volume of mud sample is kept at a specified air pressure for 30 minutes. The amount of filtrate flowing out is the water loss. The sample is taken out, the floating slurry is washed off, and the thickness of the mud cake can be measured.
[0076] Table 5 shows the properties of cement slurry compositions at different ratios
[0077]
[0078]
[0079] In the specific scheme of the present invention, the cement slurry composition is compounded with soda ash, CMC, light-burned magnesium and adhesive auxiliary materials on the basis of the base material bentonite, so as to further increase the viscosity, specific gravity and stability of the mud, thereby improving the wall protection effect. Furthermore, on the basis of the above-mentioned compound composition, 5% by weight of sawdust components are further added, and the sawdust is suspended and distributed in the mud through the mud circulation. When the mud diffuses and loses, the sawdust is taken away and filled in the gaps of the groove wall, thereby preventing the loss of mud. The cement slurry composition with this ratio is applied to the upper water-rich gravel layer trenching construction process, which has a good technical effect.
[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.
Claims
1. A cement slurry composition for ground-connected wall construction in water-rich gravel strata, characterized in that: The unit cubic meter includes the following raw materials in parts by weight: 170-200 parts of bentonite, 8-15 parts of soda ash, 4-8 parts of CMC, 1-2.5 parts of light-burned magnesia, 1-2 parts of adhesive, and 900-1000 parts of water; it also includes sawdust, and the weight percentage of the sawdust in the cement slurry composition is in the range of 4-8%.
2. The cement slurry composition for ground-connected wall construction in water-rich gravel strata according to claim 1, characterized in that: The unit cubic meter includes the following raw materials in parts by weight: 180-190 parts of bentonite, 10-13 parts of soda ash, 5-7 parts of CMC, 1-2 parts of light-burned magnesia, 1.2-1.6 parts of binder, and 950-980 parts of water.
3. The cement slurry composition for ground-connected wall construction in water-rich gravel strata according to claim 2, characterized in that: The unit cubic meter includes the following raw materials in parts by weight: 186 parts of bentonite, 11.6 parts of soda ash, 5.58 parts of CMC, 1.49 parts of light-burned magnesia, 1.4 parts of adhesive, and 955 parts of water. The weight percentage of the sawdust is 5%.
4. The cement slurry composition for ground-connected wall construction in water-rich gravel strata according to claim 3, characterized in that: The weight percentage of the sawdust is 5-6%.
5. The cement slurry composition for ground-connected wall construction in water-rich gravel strata according to claim 4, characterized in that: The weight percentage of the sawdust is 5%.
6. The cement slurry composition for ground-connected wall construction in water-rich gravel strata according to claim 4, characterized in that: The raw material of sawdust is at least one of oak, pine and birch.
7. The cement slurry composition for ground-connected wall construction in water-rich gravel strata according to claim 4, characterized in that: The particle size of the sawdust is any one of 6 mesh and 10 mesh.
8. A method for preparing a cement slurry composition according to any one of claims 1 to 7, characterized in that: The steps include: S1, mixing bentonite and water in proportion, and stirring evenly to obtain a first mixed solution; S2, adding soda ash, CMC, light-burned magnesium and a binder into water in proportion, and stirring evenly to obtain a second mixed solution; S3, mixing the first mixed liquid and the second mixed liquid, and then mixing sawdust into the mixed liquid according to a certain proportion and stirring evenly to obtain a cement slurry composition.
9. The method for preparing the cement slurry composition according to claim 8, characterized in that: The preparation method also includes S4, performing a performance test on the cement slurry composition: preparing experimental instruments according to target performance indicators, and then swelling the prepared cement slurry composition for at least 24 hours to form a mud sample, and testing the performance of the mud sample using corresponding experimental instruments. When the mud sample has indicators that do not meet the standards, the proportions are corrected again according to steps S1-S3 to obtain a cement slurry composition that meets the standards.
10. An application of a cement slurry composition, characterized in that: The cement slurry composition is used for the construction of ground-anchored walls in water-rich gravel formations.