Ecological grouting material based on shield muck and fiber modified and performance evaluation method

Abstract

The application discloses an ecological grouting material based on shield muck and fiber modification and a performance evaluation method thereof, and the method comprises the following steps: in step S1, performance index parameters of the ecological grouting material are obtained; in step S2, based on the performance index parameters, composite weight values of each performance index of the ecological grouting material are calculated by using composite weight; and in step S3, based on the composite weight values, a comprehensive evaluation value of the ecological grouting material is obtained by using a comprehensive performance evaluation method. The toughness of the grouting material is improved by adding fibers in the grouting material, and the shortcomings of the existing shield muck prepared grouting material, such as low strength and poor toughness, are improved. Meanwhile, environmental pollution caused by a large amount of shield muck accumulation is relieved, and financial and material resources consumed by shield muck transportation are reduced, so that ecological benefits and economic benefits are combined.

Description

Technical Field

[0001] The present invention relates to the technical field of grouting materials, and in particular to an ecological grouting material based on shield slag and fiber modification and a performance evaluation method. Background Art

[0002] As an essential part of people's daily lives, underground tunnel transportation naturally becomes a crucial component of underground space utilization. Shield tunneling, one of many underground construction technologies, has gradually become the mainstream technology for underground tunneling projects due to its efficiency and safety. However, as shield machines advance, soil, rock, and other materials from various strata are expelled and accumulated on the surface, becoming waste shield waste.

[0003] Currently, the resource-resource utilization of shield excavation waste to prepare shield simultaneous grouting slurry has become a new approach to addressing the shield excavation waste problem. Extensive research has been conducted domestically and internationally on the use of shield excavation waste to prepare grouting materials, with significant results. However, many existing studies have encountered shortcomings such as low strength and poor toughness in the grouting slurry prepared from shield excavation waste. Furthermore, existing studies have only proposed the materials and preparation methods for the grouting materials, without evaluating the performance of the resulting grouting materials.

[0004] When fibers are added to the grouting material, the fiber monofilaments become integrated with the grouting material, improving the material's continuity. Furthermore, the fibers share stress with the grouting material and share deformation, thereby increasing its strength and toughness. Therefore, it is necessary to propose a performance evaluation method for eco-grouting materials based on shield tunneling debris and fiber modification to address current issues. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an ecological grouting material based on shield slag and fiber modification, wherein the ecological grouting material is composed of shield slag, solidifying material, water, air entraining agent, and bundled monofilament fibers.

[0006] Optionally, the shield slag includes coarse sand, gravel, silt and clay.

[0007] Optionally, the solidifying material is cement.

[0008] Optionally, the monofilament or bundled fiber is one or more of polypropylene fiber, polyethylene fiber and alkali-resistant glass fiber.

[0009] The present invention also discloses a method for evaluating the performance of shield slag and fiber-modified ecological grouting materials, comprising:

[0010] Step S1, obtaining performance index parameters of the ecological grouting material;

[0011] Step S2: Based on the performance index parameters, a composite weight value of each performance index of the ecological grouting material is calculated using a composite weight;

[0012] Step S3: Based on the composite weight value, a comprehensive evaluation value of the ecological grouting material is obtained through a comprehensive performance evaluation method.

[0013] Optionally, in step S1, the performance index parameters mainly include: apparent density, consistency, setting time, water seepage rate, stone formation rate, cube compressive strength and water-land strength ratio.

[0014] Optionally, in step S2, the composite weight value W j The calculation formula is:

[0015]

[0016] Among them, W E,j is the entropy weight value of the performance index of ecological grouting materials, σ j is the comparative strength of grouting slurry performance index, r ij is the correlation coefficient between the two performance indicators of the grouting material, m represents the number of performance indicators of the grouting material, and i and j are the performance indicator numbers of the grouting material.

[0017] Optionally, the entropy weight value W of the performance index of the ecological grouting material E,j The calculation method is:

[0018]

[0019] Among them, e j It represents the information entropy of index j, and the calculation method is: Where n represents the number of experimental groups, P kj It represents the probability of k groups of j indicators after normalization. The normalization method is: x k,j ' represents the normalized value of the kth group j indicator parameter, x k,j represents the initial value of the kth group j indicator parameter, x jmax 、x jmin They represent the initial maximum and minimum values ​​of the j indicator parameter respectively.

[0020] Optionally, in step S3, the comprehensive evaluation value H is calculated as follows:

[0021]

[0022] Among them, W j Indicates the composite weight value of grouting material performance index, x j + 、x j- They represent the optimal and worst values ​​of the j indicator parameter, respectively, and k is the test group code.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. By adding fiber to the grouting material, the toughness of the grouting material is improved, overcoming the low strength and poor toughness of the existing grouting material made from shield excavation debris. This also alleviates the environmental pollution caused by the accumulation of large amounts of shield excavation debris and reduces the financial and material resources consumed in the transportation of shield excavation debris, achieving both ecological and economic benefits.

[0025] 2. The performance evaluation method of the present invention can quickly calculate the comprehensive performance evaluation value of the grouting material, thereby enabling the performance of the grouting material to be evaluated more quickly and accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0027] Figure 1 This is a flow chart for preparing the grouting material according to an embodiment of the present invention;

[0028] Figure 2 This is a flow chart of a method for evaluating the performance of grouting materials according to an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Example 1

[0032] An ecological grouting material based on shield slag and fiber modification, the preparation process is as follows Figure 1 As shown, the ecological grouting material consists of shield slag, solidification material, water, air entraining agent, and bundled monofilament fibers.

[0033] Based on this embodiment, the shield tunnel passes through a silty clay layer. By analyzing the properties of the shield slag generated during the construction of the tunnel and the research results on the preparation of grouting materials from existing shield slag, the ratio of the grouting material was determined based on the test of various performance indicators of the grouting material. Specifically, it is: 1 part by weight of cement, 10.3 parts by weight of shield slag, 3.2 parts by weight of water, 0.02 parts by weight of air-entraining agent, and 0.0125 parts by weight of polypropylene fiber. This ratio is set as the 4# experimental group.

[0034] The specific preparation process is as follows: first, use a hoist to flip the shield slag from the slag storage pool and lift it to the mixing system with the vibration device for loading. Then, activate the mixing and water adding system to prepare the slag slurry. At the same time, use the vibration screening system to store the slurry with a particle size of ≤2.36mm for standby use. After that, the screened slurry is discharged into the aeration tank for continuous aeration. At the same time, start the slurry mixing system, pump the slurry into the slurry mixing tank, add curing material, air entraining agent, and fiber for stirring and modulation, and finally pump the prepared slurry into the mortar tank for use.

[0035] Specifically, the grouting material performance index test includes testing of apparent density, consistency, setting time, water seepage rate, stone rate, cube compressive strength and water-land strength ratio.

[0036] The main components of the ecological grouting material proposed in this embodiment include: shield slag, solidifying material, water, air-entraining agent, and bundled monofilament fibers. The shield slag includes coarse sand, gravel, silt and clay; the solidifying material is cement; and the bundled monofilament fibers are one or more of polypropylene fiber, polyethylene fiber, and alkali-resistant glass fiber. The addition of fibers connects countless fiber monofilaments with the grouting material. The fibers and the grouting material are deformed by the expansion force of the soil together, and the fibers increase the longitudinal deformation of the grouting material due to their huge elongation during crack expansion, providing space for expansion deformation, attenuating the expansion force, and thus enhancing the strength and toughness of the grouting material. In addition, the preparation of this grouting material consumes a large amount of shield slag, reuses the discarded shield slag, alleviates the environmental pollution caused by the accumulation of a large amount of shield slag, and reduces the financial and material resources consumed in the transportation of shield slag, thereby achieving both ecological and economic benefits.

[0037] Based on the ecological grouting material prepared in the embodiment, the performance of the obtained ecological grouting material was evaluated. The specific process is as follows: Figure 2 As shown:

[0038] Three other groups of grouting materials with different proportions were set up for comparison with the 4# experimental group. Among them:

[0039] The mix ratio of experimental group 1# is: 1 part by weight of cement, 10.3 parts by weight of shield slag, 3.2 parts by weight of water, and 0.02 parts by weight of air entraining agent.

[0040] The mix ratio of experimental group 2# is: 1 part by weight of cement, 10.3 parts by weight of shield slag, 3.2 parts by weight of water, 0.02 parts by weight of air entraining agent, and 0.005 parts by weight of polypropylene fiber.

[0041] The 3# control group's mix ratio was: 1 part by weight cement, 10.3 parts by weight shield slag, 3.2 parts by weight water, 0.02 parts by weight air-entraining agent, and 0.01 parts by weight polypropylene fiber. Four different grouting materials were prepared using these four different raw material ratios, and the performance parameters of each grouting material were tested.

[0042] Step S1: Obtain the performance index parameters of the ecological grouting material. The specific test method for each performance index parameter of the grouting material is as follows:

[0043] 1. Apparent density: The ratio of mass to volume of 1L of slurry measured by an electronic scale with an accuracy of 0.1g and a measuring range of more than 3kg.

[0044] 2. Consistency: Pour the slurry into the test container until the liquid level is about 10mm below the edge of the container. Then vibrate and tap to make the liquid level flat. Then place the container on the consistency tester, adjust the test cone until it just touches the surface, lock the test cone, and return the reading dial to zero. Then release the test cone and let it fall for 10 seconds. Record the sinking distance, which is the measured consistency value.

[0045] 3. Setting time: Pour the slurry into the experimental container until the liquid level is about 10mm below the edge of the container, then vibrate and tap to make the liquid surface flat. Place the container on the tester, adjust the probe so that it just touches the liquid surface, set the pressing depth to 25mm, lock it, and adjust the reading disk to zero, then press the probe in evenly in 10 seconds and record the reading. Measure once every 30 minutes from the formation of the slurry. When the probe resistance reaches 0.3MPa, change it to once every 15 minutes, ensuring that each needle position is at least 12mm away from the previous position and the edge of the container. While recording, draw a resistance-time relationship diagram, starting from the time of adding water and stirring. The time corresponding to the resistance value of 0.5MPa in the figure is the setting time. The resistance value calculation formula is f p Indicates resistance value (MPa, accuracy 0.01), N p represents the static pressure (N) when the penetration depth is 25 mm, A p Indicates the cross-sectional area of ​​the test needle, take 30mm 2 .

[0046] 4. Water exudation rate and stone formation rate: Fill 250mL of slurry into a 250mL measuring cylinder, wait for 1 minute, measure the initial liquid level a0, and then seal the cylinder. After three hours, measure the scales a1 and a2 corresponding to the water exudation level and the slurry surface. According to the formula To calculate the water bleeding rate, the result is accurate to 0.1%; after three days, measure the scale value a3 of the hardened slurry page, according to the formula To calculate the stone rate, the result is accurate to 0.1%.

[0047] 5. Cube compressive strength: The slurry was placed in a cube mold with a side length of 70.7 mm, and then placed in a 20°C test room for 24 hours. After demoulding, the cube compressive strength test was performed after curing for 28 days at 20°C and 99% relative humidity. According to the formula The cube compressive strength value is calculated, where f m,cu is the cubic compressive strength of the grouting material (MPa), N u is the maximum load when the specimen breaks (N), A is the pressure bearing area (mm 2 ), k is the conversion coefficient, and its value is 1.35.

[0048] 6. Water-land intensity ratio: The calculation formula is: Where S R represents the water-land intensity ratio, S w represents the compressive strength of the specimen cured in water for 28 days (MPa), S a Represents the compressive strength (MPa) of the specimen cured in air for 28 days.

[0049] After the above experimental tests, the performance index parameters of four groups of grouting materials with different fiber content are shown in Table 1.

[0050] Table 1

[0051]

[0052] Step S2: Based on the performance index parameters, a composite weight value of each performance index of the ecological grouting material is calculated using a composite weight.

[0053] The composite weight values ​​of the performance index parameters of the four groups of grouting materials with different fiber content are calculated by the composite weight calculation formula of the performance index parameters of the grouting materials. The composite weight calculation formula of the performance index parameters of the grouting materials is as follows:

[0054]

[0055] Where W j Represents the composite weight value of grouting material performance index, W E,j is the entropy weight value of the grouting material performance index, σ j is the comparative strength of grouting slurry performance index, r ij is the correlation coefficient between the two performance indicators of the grouting material, m represents the number of performance indicators of the grouting material, and i and j are the performance indicator numbers of the grouting material.

[0056] The entropy weight method is calculated as follows: Where W E,j represents the weight value of the entropy weight method of the j indicator parameter, m is the number of indicators, e j It represents the information entropy of index j, and the calculation method is: Where n represents the number of experimental groups, P kj It represents the probability of k groups of j indicators after normalization. The normalization method is: x k,j ' represents the normalized value of the kth group j indicator parameter, x k,j represents the initial value of the kth group j indicator parameter, x jmax 、x jmin They represent the initial maximum and minimum values ​​of the j indicator parameter respectively.

[0057] Performance index comparison strength σ j The calculation method is Where x k,j represents the initial value of the kth group j indicator parameter, represents the average value of the initial value of the j indicator parameter, and n represents the number of experimental groups.

[0058] Correlation coefficient r ij The calculation method is

[0059] Where x k,i represents the initial value of the index parameter of group i in k, x k,j represents the initial value of the kth group j indicator parameter, represents the average value of the initial value of the i indicator parameter, represents the average value of the initial value of the j indicator parameter, and n represents the number of experimental groups.

[0060] The calculation results are recorded in Table 2.

[0061] Table 2

[0062]

[0063] Step S3: Based on the composite weight value, obtain the comprehensive evaluation value H of the ecological grouting material through a comprehensive performance evaluation method. k .

[0064] The comprehensive evaluation value of grouting materials at different fiber content is calculated using the comprehensive performance evaluation formula of grouting materials. The calculation formula is: Where W j Indicates the composite weight value of grouting material performance index, x j + 、x j -They represent the optimal and worst values ​​of the j indicator parameter, respectively, m is the number of indicators, k is the test group code, and j is the performance indicator code.

[0065] The calculation results are shown in Table 3.

[0066] Table 3

[0067] Experimental group number <![CDATA[Comprehensive evaluation value H k > 1# 1.91 2# 49.39 3# 69.01 4# 98.07

[0068] Based on the comprehensive evaluation values ​​of the grouting materials at different fiber content shown in Table 3, the comprehensive evaluation values ​​of experimental groups 1# and 2# are lower than that of the control group 3#, so they are unqualified. The performance evaluation value of the grouting material of experimental group 4# is higher than that of the control group 3#, so the grouting material of experimental group 4# is qualified.

[0069] According to the content disclosed in this embodiment, the grouting material of this embodiment makes up for the shortcomings of low strength and poor toughness of the existing grouting material prepared from shield slag. At the same time, the performance evaluation method mentioned in the present invention can quickly calculate the comprehensive performance evaluation value of the grouting material, and thus can evaluate the performance of the grouting material more quickly and accurately.

[0070] Example 2

[0071] An evaluation system for the performance of shield slag and fiber-modified eco-grouting materials, comprising:

[0072] The composite weight calculation module is used to calculate the composite weight value of each performance index of the ecological grouting material using composite weights based on performance index parameters.

[0073] The composite weight values ​​of the performance index parameters of the four groups of grouting materials with different fiber content are calculated by the composite weight calculation formula of the performance index parameters of the grouting materials. The composite weight calculation formula of the performance index parameters of the grouting materials is as follows:

[0074]

[0075] Where W j Represents the composite weight value of grouting material performance index, W E,j is the entropy weight value of the grouting material performance index, σ j is the comparative strength of grouting slurry performance index, r ij is the correlation coefficient between the two performance indicators of the grouting material, m represents the number of performance indicators of the grouting material, and i and j are the performance indicator numbers of the grouting material.

[0076] The entropy weight method is calculated as follows: Where W E,j represents the weight value of the entropy weight method of the j indicator parameter, m is the number of indicators, e jIt represents the information entropy of index j, and the calculation method is: Where n represents the number of experimental groups, P kj It represents the probability of k groups of j indicators after normalization. The normalization method is: x k,j ' represents the normalized value of the kth group j indicator parameter, x k,j represents the initial value of the kth group j indicator parameter, x jmax 、x jmin They represent the initial maximum and minimum values ​​of the j indicator parameter respectively.

[0077] Performance index comparison strength σ j The calculation method is Where x k,j represents the initial value of the kth group j indicator parameter, x j represents the average value of the initial value of the j indicator parameter, and n represents the number of experimental groups.

[0078] Correlation coefficient r ij The calculation method is

[0079] Where x k,i represents the initial value of the index parameter of group i in k, x k,j represents the initial value of the kth group j indicator parameter, represents the average value of the initial value of the i indicator parameter, represents the average value of the initial value of the j indicator parameter, and n represents the number of experimental groups.

[0080] The calculation results are recorded in Table 4.

[0081] Table 4

[0082]

[0083] A comprehensive evaluation module is used to obtain the comprehensive evaluation value H of the ecological grouting material based on the composite weight value through a comprehensive performance evaluation method. k .

[0084] The comprehensive evaluation value of grouting materials at different fiber content is calculated using the comprehensive performance evaluation formula of grouting materials. The calculation formula is: Where W j Indicates the composite weight value of grouting material performance index, x j + 、x j - They represent the optimal and worst values ​​of the j indicator parameter, respectively, m is the number of indicators, k is the test group code, and j is the performance indicator code.

[0085] The calculation results are shown in Table 5.

[0086] Table 5

[0087] Experimental group number <![CDATA[Comprehensive evaluation value H k > 1# 1.91 2# 49.39 3# 69.01 4# 98.07

[0088] Based on the comprehensive evaluation values ​​of the grouting materials at different fiber content shown in Table 5, the comprehensive evaluation values ​​of experimental groups 1# and 2# are lower than that of the control group 3#, so they are unqualified. The performance evaluation value of the grouting material of experimental group 4# is higher than that of the control group 3#, so the grouting material of experimental group 4# is qualified.

[0089] According to the content disclosed in this embodiment, the grouting material of this embodiment makes up for the shortcomings of low strength and poor toughness of the existing grouting material prepared from shield slag. At the same time, the performance evaluation method mentioned in the present invention can quickly calculate the comprehensive performance evaluation value of the grouting material, and thus can evaluate the performance of the grouting material more quickly and accurately.

[0090] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for evaluating the performance of an eco-grouting material based on shield slag and fiber modification, characterized by: The ecological grouting material is composed of shield slag, solidifying material, water, air entraining agent, and bundled monofilament fibers; the shield slag includes coarse sand, gravel, silt and clay; the solidifying material is cement; and the bundled monofilament fibers are one or more of polypropylene fibers, polyethylene fibers and alkali-resistant glass fibers; The evaluation method includes: Step S1, obtaining performance index parameters of the ecological grouting material; Step S2: Based on the performance index parameters, a composite weight value of each performance index of the ecological grouting material is calculated using a composite weight; Step S3: Based on the composite weight value, a comprehensive evaluation value of the ecological grouting material is obtained by a comprehensive performance evaluation method; In step S1, the performance index parameters mainly include: apparent density, consistency, setting time, water bleeding rate, stone formation rate, cube compressive strength and water-land strength ratio; In step S2, the composite weight value The calculation formula is: in, is the entropy weight value of the performance index of ecological grouting materials, is the comparative strength of grouting slurry performance index, r ij is the correlation coefficient between the two performance indicators of the grouting material, m represents the number of performance indicators of the grouting material, and i and j are the performance indicator numbers of the grouting material.

2. The method for evaluating the performance of shield slag and fiber-modified ecological grouting materials according to claim 1, characterized in that: The entropy weight value of the performance index of the ecological grouting material The calculation method is: Among them, e j It represents the information entropy of index j, and the calculation method is: , where n represents the number of experimental groups, P kj It represents the probability of k groups of j indicators after normalization. The normalization method is: , x k,j ' represents the normalized value of the kth group j indicator parameter, x k,j represents the initial value of the kth group j indicator parameter, x jmax 、x jmin They represent the initial maximum and minimum values ​​of the j indicator parameter respectively.

3. The method for evaluating the performance of shield slag and fiber-modified ecological grouting materials according to claim 1, characterized in that: In step S3, the comprehensive evaluation value H is calculated as follows: Among them, W j Represents the composite weight value of the performance index of ecological grouting materials, x j + 、x j - They represent the optimal and worst values ​​of the j indicator parameter, respectively, and k is the test group code.

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