Method for selecting proportion of clay cement slurry

Abstract

The application discloses a kind of selection methods of clay cement slurry proportion, belong to grouting technical field, including the following steps: S1, slurry and calculus body performance test is carried out: orthogonal test method is configured slurry, determine orthogonal test factor, under different proportion conditions, the performance of slurry and calculus body is determined, according to linear regression analysis method analysis factor influence on slurry and calculus body performance;S2, slurry proportion is preliminarily selected: select the working performance of rock mass crack grouting, respectively, carry out factor analysis, select preliminary slurry proportion;S3, optimization slurry proportion selection: for different age under hardening clay cement slurry XRD diffraction test, scanning electron microscope test, thermodynamic test, carry out clay cement slurry microcharacteristics research, preliminary selection slurry proportion is optimized.The application discloses a kind of selection methods of clay cement slurry proportion, can select appropriate slurry proportion according to different working conditions, better improve grouting effect, reduce engineering cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of grouting, in particular to a selection method of clay cement slurry ratio. BACKGROUND

[0002] In recent years, with the increase of mining intensity and the enhancement of groundwater resource protection awareness, water disaster and water resource protection problems in open-pit mines have become important bottleneck problems for safe and green mining in open-pit mines. In addition to carrying out various predictions, evaluations and mechanism researches, the more important thing for water disaster prevention and control in open-pit coal mines is advanced prevention and post-disaster treatment.

[0003] Grouting and plugging is the most important engineering means for water prevention and control in open-pit mines. In the early stage of the development of grouting and plugging technology, cement slurry is usually used as the grouting material for water-stopping curtain in coal mines. However, cement material has the characteristics of high price, easy to cause environmental pollution and high carbon emission, so people have been looking for an environmentally friendly, economical, water-stopping effect good and can replace cement slurry grouting material.

[0004] Clay cement slurry has its own water plugging performance. The use of clay cement slurry can greatly reduce the engineering cost, and it has the characteristics of non-toxic and harmless, and achieves ideal grouting effect in leakage plugging and seepage prevention engineering, further making the application prospect of this kind of slurry broad. However, due to different ratios of clay cement slurry, the grouting effect is also different.

[0005] Therefore, in the design of grouting engineering, the selection of slurry is an important link, which directly affects the quality of grouting and the cost of engineering. In order to better provide grouting effect and reduce engineering cost, it is necessary to select appropriate slurry ratio according to different working conditions. SUMMARY

[0006] The purpose of the present application is to provide a selection method of clay cement slurry ratio, which can better improve the grouting effect and solve the problem that different ratios of clay cement slurry lead to different grouting effects, thereby affecting the quality of grouting.

[0007] To achieve the above purpose, the present application provides a selection method of clay cement slurry ratio, which comprises the following steps:

[0008] S1, slurry and stone performance test: orthogonal test method is used to configure the slurry, the orthogonal test factors are determined, the performance of the slurry and the stone is measured under different ratio conditions, the performance of the slurry includes specific gravity, viscosity, sand content and setting time, the performance of the stone includes stone rate, tensile strength, compressive strength and elastic modulus, and the influence of orthogonal test factors on the performance of slurry and stone is analyzed according to linear regression analysis method;

[0009] S2, preliminary selection of slurry ratio: select the working performance of rock mass crack grouting, analyze the influencing factors respectively, and select the preliminary slurry ratio;

[0010] S3, optimization of slurry ratio selection: carry out XRD diffraction test, scanning electron microscope test and thermodynamic test on hardened clay cement slurry at different ages, carry out microstructure research of clay cement slurry, and optimize the preliminary selection of slurry ratio.

[0011] Preferably, in S1, the orthogonal test factors include water-cement ratio, cement dosage and accelerator dosage, wherein the water-cement ratio is 1:1, 1.25:1, 1.5:1, 1.75:1, 2:1, the cement dosage is 10%, 20%, 30%, 40%, 50%, and the accelerator dosage is 0, 1%, 3%, 5%, 10%.

[0012] Preferably, in S2, the working performance of rock mass crack grouting includes injectability, plasticity, impermeability and seismic resistance.

[0013] Preferably, S3 includes the following steps:

[0014] S31, obtain the mineral composition and content of hardened clay cement slurry at different hydration ages by X-ray diffraction, and analyze the hydration process and hydration products of clay cement slurry;

[0015] S32, observe the microstructure of hardened clay cement slurry at different ages by SEM scanning electron microscope, determine the types of hydration products, and compare and verify the hydration products analyzed by X-ray diffraction at corresponding ages;

[0016] S33, obtain the time change rule of heat release of clay cement slurry in the hydration process by thermodynamic test, and verify it, and optimize the preliminary selection of slurry ratio.

[0017] Preferably, in S31, the hydration process of clay cement slurry is analyzed mainly by the change of the composition and content of cement, clay and newly generated minerals.

[0018] Preferably, in S32, the types of hydration products are determined by observing the specific shape of different hydration products.

[0019] Preferably, in S33, the verification process is to verify the heat release change of the hydration reaction process analyzed by X-ray diffraction and scanning electron microscope with the thermodynamic test results.

[0020] Therefore, the selection method of the clay cement slurry ratio can select appropriate slurry ratio according to different working conditions; through the basic performance test of the slurry, the linear regression method is used to obtain the influence of the increment of each factor on the basic performance of the slurry, according to the test results, the preliminary selection method of the slurry ratio meeting four working performances is obtained, through the micro test, the solidification reaction mechanism of the slurry is studied, and the preliminary selection method of the slurry ratio is optimized, so that the grouting effect is better improved, and the engineering cost is reduced.

[0021] The technical solutions of the present application are further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is the relationship between the specific gravity of the clay-cement slurry of each ratio and the cement increment of the present application;

[0023] Figure 2 The figure is the relationship between the sand content of the clay-cement slurry of each ratio and the cement increment of the present application;

[0024] Figure 3 The figure is the relationship between the viscosity of the clay-cement slurry of each ratio and the cement increment of the present application;

[0025] Figure 4 The figure is the relationship between the 24-hour water separation rate of the clay-cement slurry of each ratio and the cement increment of the present application;

[0026] Figure 5 The figure is the relationship between the initial setting time of the clay-cement slurry of each ratio and the cement increment of the present application;

[0027] Figure 6 The figure is the relationship between the final setting time of the clay-cement slurry of each ratio and the cement increment of the present application;

[0028] Figure 7 The figure is the relationship between the stone formation rate of the clay-cement slurry of each ratio and the cement increment of the present application;

[0029] Figure 8 The figure is the relationship between the impermeability strength of the stone body of the clay-cement slurry of each ratio and the cement increment of the present application;

[0030] Figure 9 The figure is the relationship between the compressive strength of the stone body of the clay-cement slurry of each ratio and the cement increment of the present application;

[0031] Figure 10 The figure is the relationship between the tensile strength of the stone body of the clay-cement slurry of each ratio and the cement increment of the present application;

[0032] Figure 11 The figure is the relationship between the elastic modulus of the stone body of the clay-cement slurry of each ratio and the cement increment of the present application;

[0033] Figure 12 Fig. 8 is a graph of the relationship between the plastic strength of the clay-cement slurry of the present application and the cement content;

[0034] Figure 13 Fig. 9 is an X-ray diffraction pattern of the hydration product of the present application, wherein Fig. (a) is an X-ray diffraction pattern of the hydration product at different curing ages, and Fig. (b) is an X-ray diffraction pattern of the hydration product of different groups;

[0035] Figure 14 Fig. 10 is a fracture of the stone body of the clay solidification slurry of the present application;

[0036] Figure 15 Fig. 11 is a thermodynamic test result of the present application. DETAILED DESCRIPTION

[0037] The technical solutions of the present application are further described below by means of the accompanying drawings and examples.

[0038] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application.

[0039] EMBODIMENT

[0040] The present application provides a selection method of clay-cement slurry ratio, comprising the following steps:

[0041] (1) Slurry and stone body performance test

[0042] The orthogonal test method is used to configure the slurry, the orthogonal test factors are determined, the specific gravity, viscosity, sand content, setting time of the slurry, and the stone rate, tensile strength, compressive strength and elastic modulus of the stone body are measured under different ratio conditions, and the influence of each orthogonal test factor on the performance of the slurry and the stone body is analyzed according to the test results.

[0043] The orthogonal test factors include water-cement ratio, cement content and accelerator content.

[0044] Table 1 below is the orthogonal test scheme, the water-cement ratio is selected as 1:1, 1.25:1, 1.5:1, 1.75:1 and 2:1;

[0045] The cement content is 10%, 20%, 30%, 40% and 50%;

[0046] The accelerator content is 0, 1%, 3%, 5% and 10%.

[0047] The linear regression analysis method is used to analyze the test results of the slurry performance, and the relationship graph between the slurry performance and the cement content is obtained, as shown in Fig. 1. Figures 1-12 Fig. 1 is a graph of the relationship between the slurry performance and the cement content of the present application.

[0048] Table 1 orthogonal test scheme

[0049]

[0050] 2) Propose the preliminary selection method of slurry ratio

[0051] The present application proposes rock mass fracture grouting working performance including injectability, plasticity, impermeability and anti-seismic performance, and indicates the relationship between slurry and stone body performance and the four working performances. The injectability is related to the viscosity, 24-hour water separation rate and setting time of the slurry; the plasticity is related to the 24-hour water separation rate, stone rate and plastic strength of the slurry; the impermeability is related to the stone rate, permeability coefficient and compressive strength of the stone body; and the anti-seismic performance is related to the plastic strength, compressive strength and elastic modulus of the stone body.

[0052] ① Injectability

[0053] The injectability of the slurry is determined by the diffusion radius of the slurry in the stratum, so the factors affecting the injectability of the slurry are the factors affecting the diffusion radius of the slurry. The diffusion radius of the slurry is mainly affected by two aspects, namely the rheological property of the slurry and the stability of the slurry.

[0054] a. Influence of rheological property of slurry on injectability

[0055] The diffusion radius of the slurry in the stratum is the basis for determining the injectability of the slurry, and the main influencing factor of the diffusion radius of the slurry is the rheological property of the slurry, and the main factors affecting the rheological property are the viscosity and setting time.

[0056] The rheological property of the slurry will be affected by the setting time of the slurry. The clay cement slurry will show different setting times due to different amounts of accelerators and clay cements. The setting time can only consider a reasonable range of clay amount and water-cement ratio. When the water-cement ratio is 1:1, the setting time is the smallest, which is 351 minutes. The slurry cannot effectively diffuse in the rock fracture, which is not desirable. When the water-cement ratio is greater than 1.5:1, the setting time is too long. In actual engineering conditions, under strong water-rich conditions, a long setting time will cause the slurry to be washed away by water, which cannot achieve the effect of grouting. Therefore, when the water-cement ratio is 1.25:1 or 1.5:1, it is more reasonable.

[0057] b. Influence of stability on injectability

[0058] The stability of clay cement slurry is also considered in the injectability. When the slurry with high water separation rate flows in the pore of the injected body, the flow section of the slurry decreases with the settlement of the particles. The viscosity of the slurry in the upper part of the pore decreases due to the water separation, resulting in the increase of the flow speed. However, the viscosity of the slurry in the lower part increases, resulting in the decrease of the flow speed. In addition, the water-cement ratio of the settled slurry decreases, the setting time of the slurry shortens, and the slurry plug is formed, which prevents the forward diffusion of the following slurry, and the diffusion distance of the slurry decreases.

[0059] When the slurry with high water separation rate flows in the pore of the injected body, the flow section of the slurry decreases with the settlement of the particles. The viscosity of the slurry in the upper part of the pore decreases due to the water separation, resulting in the increase of the flow speed. However, the viscosity of the slurry in the lower part increases, resulting in the decrease of the flow speed. When the water-cement ratio is less than or equal to 1.5:1, the water separation rate is less than 30%, and the stability is good.

[0060] The smaller the viscosity of the slurry, the better the flowability, and the larger the diffusion radius, the better the injectability of the slurry. However, in order to prevent the slurry from diffusing too far, the slurry consumption is large, and the viscosity is too low, which is easy to be washed away in the water-rich environment. When the water-cement ratio is too large, the stability of the slurry decreases. Therefore, the viscosity of the slurry should not be too low, and the water-cement ratio should not be too high. At the same time, the lower the setting time of the slurry, the faster the slurry solidifies, the smaller the diffusion radius, and the worse the injectability. However, if the setting time is too long, the slurry is easy to be washed away in the water-rich environment, which is not conducive to the grouting in Xiyuan Open-pit Coal Mine.

[0061] In summary, according to the test results of viscosity, 24-hour water separation rate, and setting time, the optimal proportioning range of the slurry meeting the injectability requirements is: the viscosity is 90 MPa.s-260 MPa.s, the 24-hour water separation rate is less than 30%, and the water-cement ratio of the slurry is 1.5:1 or 1.25:1.

[0062] Table 2 Performance requirements of the slurry meeting the injectability

[0063]

[0064] ② Plasticity

[0065] The plasticity of the grouting requires that the slurry can continuously and stably fill the rock fissures after the grouting is completed. Therefore, the main related indicators of the plasticity are the stability indicators of the slurry, i.e. the stone rate test and the stability test. In addition, the slurry should fill all the pores as much as possible, which requires a high consistency of the slurry. The higher the consistency, the better the flowability, and the slurry can penetrate into smaller fissures, which can better solve the water leakage problem in the mine area. Therefore, the study on the plasticity law mainly considers the stone rate, stability, flowability, and plastic strength of the slurry. The flowability has been studied in the previous study, and the plasticity of the slurry is mainly described in terms of the stability, stone rate, and plastic strength.

[0066] a. The influence of the stone rate on the plasticity

[0067] The slurry stone rate directly affects the filling and consolidation effect of the slurry on the water-containing structure such as voids. The higher the slurry stone rate, the smaller the remaining pore cracks after grouting, the stronger the blocking ability of the water section, and the lower the possibility of residual leakage water in the later period. Under the same conditions, a grouting material with a high stone rate should be preferred. The higher the stone rate, the better the water stopping effect. In actual fissure grouting engineering, it is considered that a stone rate of more than 65% can be considered to have good water stopping effect.

[0068] b. The influence of the water separation rate on the plasticity

[0069] The water separation rate of the slurry refers to the rate of water separated due to the sedimentation of cement particles in the slurry under static conditions. The size of the water separation rate is an indicator of the stability of the slurry. If the water separation rate of the slurry is too high, the remaining stone volume after grouting will be smaller, and the filling effect on the rock mass fissure will be poorer. At the same time, the separated water coexists with the cement clay in the fissure channel and will have a great impact on the shape of the final stone under the action of vibration. It is generally considered that a slurry with a water separation rate of less than 30% meets the requirements of grouting engineering.

[0070] c. The influence of the plastic strength on the plasticity

[0071] The plastic strength of the slurry is between 13 x 10 -5 MPa and 13.98 x 10 -5 MPa. With the increase of the water-cement ratio, the plastic strength of the slurry shows a downward trend, but it is not too obvious. When the water-cement ratio is constant, the increase of the cement content increases the plastic strength of the slurry, showing a positive correlation. This is because the cement added to the slurry reacts chemically with water, accelerator, and clay. Therefore, the increase of the cement content will affect the chemical reaction speed inside the slurry, thereby showing a greater influence on the increase of the plastic strength of the slurry.

[0072] According to the above analysis, the plasticity of the slurry is mainly affected by the fluidity and stability. The better the fluidity of the slurry, the stronger the ability of the slurry to flow and fill the rock mass fissure, that is, the better the plasticity of the slurry. The better the stability of the slurry, the higher the stone rate, and the stronger the filling ability after the slurry is injected into the rock mass fissure and solidified. Therefore, the better the fluidity and stability of the slurry, the higher the stone rate, and the better the plasticity of the slurry.

[0073] In summary, according to the test results of the 24-hour water separation rate, stone rate, and plastic strength, the optimal proportioning range that meets the plasticity of the slurry is: the slurry stone rate is greater than or equal to 65%, the 24-hour water separation rate is less than 30%, and the plastic strength is greater than 13.30 x 10 -5 MPa.

[0074] Table 3 meets the performance requirements of the plastic slurry

[0075]

[0076] ③ Impermeability

[0077] In fissure rock mass, grouting method is used to resist permeability and block water. The mechanism of slurry to resist permeability and block water is that the slurry has a blocking effect opposite to the direction of water flow, that is, the flow of slurry is the reverse process of water seepage. When selecting the appropriate slurry ratio, we mainly consider whether the stone body formed by the slurry after grouting can meet the demand of water resistance curtain resisting water permeability. From this aspect, we need to consider four aspects of performance, which are stone rate, impermeability, uniaxial compressive strength and elastic modulus.

[0078] a. The influence of stone rate on impermeability

[0079] The stone rate of slurry directly affects the filling and reinforcement effect of slurry on water-containing structures such as voids. The higher the stone rate of slurry, the less likely it is to separate and stratify during pumping, the more compact the sealing of water leakage channels in water-containing structures, the stronger the sealing ability of water cross section, and the lower the possibility of residual leakage of water in the later stage. Under the same conditions, high-stone-rate grouting materials should be preferred. Because the flexible water-stop curtain grouting project is different from general grouting projects, its slurry consumption is large, so the strength of the stone body of the grouting material is not high, but the stone rate has certain requirements. The higher the stone rate, the better the water stopping effect. In actual fissure grouting engineering, it is considered that the stone rate of more than 65% can be considered to have good water stopping effect.

[0080] b. The influence of permeability coefficient on impermeability

[0081] Through consulting a large amount of data, it is understood that the grouting process of clay curing slurry filling water-rich rock fissures under different grouting parameters and stratum drainage speed is simulated through indoor test, and it is obtained that the permeability coefficient of clay cement slurry stone body under indoor water-rich conditions reaches 1 x 10 -6 cm / s under water-cement ratio 1.5:1 and 28d curing, which can completely meet the design requirements of water-rich karst filling grouting.

[0082] c. The influence of compressive strength on impermeability

[0083] The compressive strength of the stone body is one of the important factors to ensure that the grouting body does not occur permeation damage, and is an important indicator of its performance. The slurry fills, penetrates, and compacts in the stratum until it is finally solidified into a stone body. With the continuous improvement of the strength of the slurry stone body and the gradual expansion of the volume, the stone body is closely combined with the stratum to be grouted. This not only improves the impermeability of the stratum, but also reinforces the stratum. Referring to the performance and application conditions of other types of slurry stone bodies, it can be considered that the compressive strength of the clay cement slurry stone body should reach 0.5 MPa to 1 MPa after 28 days to meet the requirements of anti-seepage and leakage prevention.

[0084] d. Influence of elastic modulus on impermeability

[0085] The elastic modulus of the grouting stone body is an important mechanical property, which reflects the relationship between the stress and the strain of the stone body. For the flexible waterproof curtain grouting slurry stone body, controlling the elastic modulus of the slurry stone body to meet the deformation adaptability is an important indicator of impermeability and water resistance. That is, the elastic modulus of the slurry stone body should be very low, so that the stone body can produce a certain deformation ability under certain stress, and the deformed stone body can better fill the cracks and resist water penetration.

[0086] In actual engineering, for the flexible waterproof curtain crack grouting, it is considered that the elastic modulus of the slurry stone body should be less than 1 GPa, so that the stone body can deform well under certain force, which is beneficial to the impermeability and water resistance.

[0087] According to the above analysis, the greater the stone rate of the slurry solidified body, the smaller the permeability coefficient, the greater the compressive strength, and the smaller the elastic modulus, the better the impermeability of the stone body. The main indicator affecting the impermeability of the slurry is the permeability coefficient of the slurry. The lower the permeability coefficient, the better the impermeability of the slurry. The permeability coefficient of the slurry is mainly affected by the water-cement ratio and the clay content. The higher the water-cement ratio of the slurry, the higher the permeability coefficient of the slurry, and the worse the impermeability. The second factor affecting the impermeability is the compressive strength, stone rate, and elastic modulus of the slurry. The greater the compressive strength, the stronger the resistance to static water pressure, and the slurry stone body will not be squeezed out by water pressure. At the same time, the higher the stone rate of the slurry, the more fully the slurry fills the cracks, and the better the resistance to water penetration. The lower the elastic modulus, the stronger the deformation ability of the stone body under certain stress, and the deformed stone body can better fill the cracks and resist water penetration. While the higher the water-cement ratio of the slurry, the lower the stone rate and compressive strength of the stone body, and the greater the elastic modulus. The higher the clay content, the higher the stone rate and elastic modulus, and the higher the compressive strength. Therefore, the appropriate ratio should be selected to achieve the optimal impermeability effect.

[0088] In summary, according to the test results of the stone rate, permeability coefficient and compressive strength, the optimal proportion range of the slurry that meets the impermeability of the flexible waterproof curtain is as follows: the stone rate of the slurry is greater than 65%, the permeability coefficient of the grouting stone body is less than 1 x 10 -6 cm / s, and the compressive strength is greater than 1 MPa.

[0089] Table 4 Performance requirements of the slurry that meets the impermeability

[0090]

[0091] (4) Anti-seismic property

[0092] The main function of the waterproof curtain wall is to prevent water seepage of the side slope, but it still requires strength. When the side slope in the mining area is blasted, the waterproof curtain simultaneously bears the lateral earth pressure of the side slope and the transverse impact force generated by the blasting vibration. If the waterproof curtain does not have good anti-seismic property and loses strength to produce a large deformation, the water blocking performance will also be greatly affected. When analyzing the anti-seismic property of grouting, two aspects are usually considered. One aspect is the strength of the slurry stone body, such as the tensile strength and the compressive strength. The other aspect is the stress-strain relationship of the slurry stone body, which includes the plastic strength before the slurry solidifies and the elastic modulus after the stone.

[0093] a. Influence of compressive strength on anti-seismic property

[0094] The compressive strength of the stone body directly affects the anti-seismic property of the waterproof curtain. The higher the compressive strength, the greater the pressure that the entire waterproof curtain can bear. The lower the compressive strength, the easier the waterproof curtain is damaged and loses the water blocking performance. According to the compressive strength test, the water-cement ratio shows a negative correlation with the compressive strength of the slurry. The greater the water-cement ratio, the lower the compressive strength of the stone body. Therefore, the two proportions with a too high water-cement ratio are not considered in our range. In addition, a lower cement content will also greatly reduce the compressive strength of the stone body. Therefore, when considering the compressive strength, the selection of the proportion should be that the water-cement ratio is less than or equal to 1.5:1 and the cement content is greater than 20%.

[0095] b. Influence of tensile strength on anti-seismic property

[0096] The slurry fills into the rock mass fracture under the action of grouting pressure. The development of the rock mass fracture is extremely irregular. Therefore, the shape of the slurry vein formed by the slurry is also extremely irregular, and the force received is also from different directions. In addition to pressure, the slurry may also be subjected to tension, bending, shear, and torsion. Therefore, simply detecting the compressive strength of the stone body cannot fully reflect the strength of the stone body. Therefore, it is necessary to detect the tensile strength of the stone body. The stronger the tensile strength of the stone body, the less likely it is to produce cracks and damage, and the better the water blocking performance.

[0097] c. Influence of elastic modulus on anti-seismic property

[0098] Elastic modulus is an important performance parameter of engineering materials, and it is a measure of the ability of an object to resist elastic deformation. Since the flexible waterproof curtain is used in this project, it is difficult to ensure that the waterproof curtain does not deform at all. Therefore, under the condition of not affecting the water-blocking performance, small deformation is allowed to exist. Therefore, it is necessary to measure the elastic modulus. As long as the strain caused by the stress on the curtain body does not cause cracks in the stone body and cause water seepage, it can be determined that the elastic modulus meets the requirements. The standard elastic modulus of plastic concrete is usually in the range of 0.5-3.0 Gpa, so we select the elastic modulus of 0.6 Gpa or more as the qualified clay cement slurry.

[0099] d. The influence of plastic strength on seismic performance

[0100] Plastic strength is a measure of the internal deformation and flow resistance of the slurry, which can be regarded as the shear strength of the slurry. The plastic strength of the slurry represents the shear resistance of the slurry. Since the slurry needs time to form a stone body with strength after being injected into the rock, and the force is uninterrupted, if the slurry deforms too much during the consolidation to form the stone body, it will also affect the water-blocking effect in the later period. Therefore, the plastic strength should not be too small, and the inner wall of the slurry needs a certain ability to resist deformation to prevent large deformation before the lump is formed. At the same time, the plastic strength of the slurry should not be too high, otherwise it will affect the flowability of the slurry, making it difficult to penetrate into the small cracks in the rock and play a water-blocking role.

[0101] When considering seismic resistance, we require that the plastic strength should not be too small, and should be greater than 13.3 x 10 -5 MPa.

[0102] Based on the test results of plastic strength, compressive strength, and elastic modulus, the optimal ratio of the slurry that meets the seismic resistance of the flexible waterproof curtain is selected in the range of: elastic modulus greater than or equal to 0.6 Gpa, plastic strength greater than 13.3 x 10 -5 MPa, compressive strength greater than 1 MPa, and tensile strength greater than 0.17 MPa.

[0103] Table 5 Performance requirements of slurry that meets seismic resistance

[0104]

[0105]

[0106] ⑤ Ratio selection method

[0107] Based on the above analysis, the four performance indicators of the slurry are as follows.

[0108] Table 6 range of relevant indicators

[0109]

[0110] According to the engineering practice, the required indicators are selected respectively, and the selection of slurry ratio is carried out.

[0111] Table 7 preliminary selection method of slurry ratio

[0112]

[0113]

[0114] (3) optimization of slurry ratio preliminary selection method

[0115] Firstly, the mineral composition and content of hardened clay cement slurry under different hydration ages are obtained by X-ray diffraction, and the hydration process of clay cement slurry is analyzed mainly through the change of the content of cement, clay and newly generated mineral; Then the microstructure of hardened clay cement slurry under different ages is observed by SEM scanning electron microscope, the type of hydration product is determined by observing the specific shape of different hydration products, and the hydration product analyzed by X-ray diffraction under corresponding age is compared and verified, at the same time, the distribution of pores and cracks in microstructure can also explain the macroscopic water blocking performance; Finally, the time variation rule of heat release of clay cement slurry in hydration process can be obtained by thermodynamic test, which is the macroscopic phenomenon of microcosmic hydration reaction process, the heat released by different hydration products is different, which can be verified by the heat release change of hydration reaction process analyzed by X-ray diffraction and scanning electron microscope, and the results of thermodynamic test.

[0116] In order to better explore the influence of each component of slurry on hydration reaction, according to the test results of slurry performance, we select the following five groups of ratio as the sample of solidification and water blocking mechanism research test.

[0117] Table 8 slurry ratio

[0118]

[0119] According to the XRD test results, Figure 13) analysis can be obtained, the age is 1d, each proportion of the reaction has not been fully carried out, the XRD analysis result is roughly the same; with the extension of time, the hydration reaction continues, the hydration product of each component of cement begins to increase, according to the XRD analysis result, the 9th group (water-cement ratio 1.25:1, cement addition 40%, accelerator addition 1%) and the 12th group (water-cement ratio 1.5:1, cement addition 20%, accelerator addition 3%) compared with the rest of the three groups, the generated product is more, the reaction is more complete, the generated hydration product is more, and can better play the role of cementation and fill the pores in the clay particles, and improve the strength of the sample; with the increase of curing time, the hydration reaction proceeds, and the hydration product begins to have a secondary reaction with the cations on the surface of the clay particles.

[0120] According to the scanning electron microscope test result ( Figure 14 ) analysis can be obtained, at 1d, the stone body surface can clearly see that there are microcracks and holes, at this time, the strength of the stone body is weak, and the water permeability is strong, at 7d, the cracks and holes on the surface of the stone body are greatly reduced, the water permeability of the stone body begins to gradually weaken, and the surface begins to appear hydration product enrichment phenomenon, at 28d, the hydration product is further enriched, and gradually connected into a sheet, the microcracks and holes on the surface of the stone body are greatly reduced, almost all disappear, the strength of the stone body is greatly strengthened, the water permeability is further weakened, and the structure of the slurry is improved. Therefore, at this time, it can be considered that the stone body after 28d of age as a grouting material can meet the requirements of grouting.

[0121] According to the thermodynamic test result ( Figure 15 ) can be obtained, the hydration process of clay cement slurry is similar to that of cement. The hydration process and mechanism of cement are the basis for improving the early strength. Only by fully understanding the hydration process and the reactions occurring in each process can the early strength be improved based on the reaction mechanism of the early process. The hydration process of cementitious materials can be divided into five stages: pre-induction period (dissociation period), induction period, acceleration period, deceleration period and stable period.

[0122] Through the microcharacteristics of clay cement slurry, it is shown that when the cement addition of the slurry is 20% to 40%, the solidification and water blocking effect of the stone body of the clay cement slurry is better.

[0123] Table 9 final selection method of slurry ratio

[0124]

[0125]

[0126] Therefore, the selection method of the clay cement slurry ratio can better improve the grouting effect, solve the problem that the grouting effect is different due to different clay cement slurry ratios in the background art, and thus affect the grouting quality.

[0127] It should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still make modifications or equivalent replacements to the technical solutions of the present application, and these modifications or equivalent replacements should not make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for selecting the mix proportion of clay-cement slurry, characterized in that, Includes the following steps: S1. Conduct performance tests on slurry and stone body: Use orthogonal experimental design to prepare slurry, determine orthogonal experimental factors, measure the performance of slurry and stone body under different mix ratios, and analyze the influence of orthogonal experimental factors on the performance of slurry and stone body using linear regression analysis. S2. Preliminary selection of grout mix ratio: Select the working performance of rock mass fracture grouting, analyze the influencing factors, and select the preliminary grout mix ratio; S3. Optimization of Grout Mix Ratio: XRD diffraction, scanning electron microscopy, and thermodynamic tests were conducted on hardened clay-cement grout at different ages to study the microstructure of the clay-cement grout and optimize the initial selection of the grout mix ratio; including the following steps: S31. The mineral composition and content of hardened clay-cement paste at different ages were obtained by X-ray diffraction, and the hydration process and hydration products of the clay-cement paste were analyzed. S32. The microstructure of hardened clay cement paste at different ages was observed by scanning electron microscopy (SEM) to determine the types of hydration products and to compare and verify them with the hydration products analyzed by X-ray diffraction at the corresponding ages. S33. The heat release law over time during the hydration process of clay cement slurry was obtained and verified through thermodynamic experiments, and the slurry mix ratio was initially optimized.

2. The method for selecting the proportion of clay cement slurry according to claim 1, characterized in that: In S1, the orthogonal experimental factors include water-cement ratio, cement dosage, and accelerator dosage.

3. The method for selecting the proportion of clay cement slurry according to claim 2, characterized in that: In S2, the working performance of rock mass fracture grouting includes injectability, plasticity, impermeability and seismic resistance.

4. The method for selecting the proportion of clay cement slurry according to claim 3, characterized in that: In S31, the hydration process of clay cement paste is analyzed by the changes in the composition and content of cement, clay and newly generated minerals.

5. The method for selecting the proportion of clay cement slurry according to claim 3, characterized in that: In step S32, the type of hydration product is determined by observing the specific shapes of different hydration products.

6. The method for selecting the proportion of clay cement slurry according to claim 3, characterized in that: In S33, the verification process involves estimating the change in heat release during the hydration reaction process as analyzed by X-ray diffraction and scanning electron microscopy, and verifying it with the results of thermodynamic experiments.

Images