CN112777984B

CN112777984B - Curing agent for damming material of silty dam in loess region

Info

Publication number: CN112777984B
Application number: CN202110026177.9A
Authority: CN
Inventors: 张金良; 吴向东; 杨林; 于洋; 万岳
Original assignee: Yellow River Engineering Consulting Co Ltd
Current assignee: Yellow River Engineering Consulting Co Ltd
Priority date: 2021-01-08
Filing date: 2021-01-08
Publication date: 2022-05-06
Anticipated expiration: 2041-01-08
Also published as: CN112777984A

Abstract

The invention relates to a curing agent for a damming material of a silt dam in a loess area, which consists of a powder curing component and a liquid waterproof component, wherein the powder curing component comprises the following components: 65-75 parts of slag powder, 15-30 parts of cement, 5-25 parts of fly ash, 1-7 parts of synthetic fiber, 2-5 parts of calcium sulfate and 1-5 parts of calcium hydroxide; the liquid water-proof composition comprises: 70-90 parts of emulsified PDMS polydimethylsiloxane, 5-20 parts of nano silicon dioxide solution and 1-5 parts of xanthan gum. Compared with the prior art, the gel material can be directly used for curing the loess without adding any additional gel material. In a performance test, the unconfined compressive strength of the solidified soil body can reach more than 5MPa, and the toughness and the crack resistance of the solidified soil body are improved through fibers, so that the high-strength and high-toughness solidified soil body material is formed. The prepared liquid waterproof component is adopted to enable the soil body to have hydrophobicity, so that a large amount of external moisture can be effectively prevented from permeating, and the loess collapsibility is reduced.

Description

Curing agent for damming material of silty dam in loess region

Technical Field

The invention relates to a dam construction material curing agent, in particular to a curing agent for a damming material of a silty land in a loess plateau area.

Background

The silt dam refers to a dam building constructed in each level of channels in a water and soil loss area for the purpose of blocking silt, and the soil blocked by the dam building is called a dam land. The construction of a plurality of silt dams in one ditch is an important and unique ditch treatment engineering system in severe water and soil loss areas of the loess plateau in China. The main purposes are flood detention, mud blocking, land silting, water storage, farmland construction, agricultural production development and yellow river sediment reduction. The silty dam is an effective channel treatment project summarized by the masses in loess plateau regions in the long-term competition practice for water and soil loss, is widely distributed in a ditch fork of the loess plateau to form an artificial barrier for blocking a sediment conveying channel, and plays the dual effects of silty field construction and water and soil conservation.

CN1273687C discloses a loess flow-collecting field surface flow-increasing, roughness-reducing and solidifying method, which comprises the following steps of firstly removing soil impurities on the surface layer of the earth surface, digging the soil loose, removing weeds and impurities: preparing a soil curing agent and loess according to the weight ratio of 1: 6-1: 8, uniformly mixing by spraying water, paving and tamping to ensure that the dry density is more than 1.60g/cm 3; beating slurry on the tamped collecting surface, spreading pure curing agent on the slurry to smooth the collecting surface, and enabling the roughness to reach 0.012: and (5) regularly sprinkling water on the surface of the prepared current collecting field for maintenance. The loess sloping field collecting surface constructed by the invention has the advantages that the collecting efficiency can reach 80-90%, the service life is 15-20 years, the collecting efficiency is basically the same as that of a concrete collecting surface, the loess sloping field collecting surface is pollution-free, the construction cost is 3-5 yuan/square meter and is only one third of that of the concrete collecting surface; can be widely applied to vast loess plateau and other areas without sand and stone, and has important practical significance and practical value for promoting the development of drought area rainwater collection and recharge agriculture.

The invention discloses CN108102658A a soil solidifying agent suitable for constructing a silty clay roadbed, which is prepared by mixing the main components of magnesium chloride, aluminum chloride, triethanolamine, sodium sulfate, aminobenzenesulfonate, water and an organic surfactant, and has the advantages of simple process and convenient batch production; the soil curing agent is a weak acid ionic solution type soil curing agent, is convenient to use, can well and stably cure powdery clay, and is particularly suitable for loess in elm forest areas in Shaanxi. The soil curing agent is non-toxic, harmless, non-corrosive, micro in dosage and obvious in effect; the soil solidifying agent of the invention is used to stabilize the powdery clay, can obviously improve the water damage resistance and deformation resistance of the roadbed soil, and improve the overall strength of the roadbed. Can improve the defects of difficult compaction and poor water stability of the powdery clay, and can save a large amount of traditional road building materials such as lime, cement and the like.

The existing built silt dam consists of a large dam and a water discharge building, wherein the large dam is built by adopting loess on site and is built into a homogeneous dam, and the flood control standard is low. Due to the fact that the number of the silt dam is large, the silt dam is distributed and dispersed, the management and protection task is huge, and the flood prevention standard of the silt dam is low, the silt dam is easy to break and damage when the silt dam is turned over in case of exceeding standard flood in a flood season, the exceeding standard flood formed when the upstream silt dam breaks can threaten the downstream silt dam, and therefore chain reaction is formed. In recent years, with the influence of global climate change, the probability of regional high-intensity rainstorm and extreme rainstorm flood in the yellow river basin is increased, the dam body is soaked for a long time by flood generated by continuous strong rainfall, and the probability of dam break caused by relatively high water level operation is increased. Loess has the characteristic of typical collapsibility, and can obviously reduce the strength and increase the deformation under the soaking condition, thereby threatening the safe operation and flood prevention safety of the silt dam.

Disclosure of Invention

The invention aims to solve the problems and provides a curing agent for a damming material of a silt dam in a loess plateau area, which has high flood control standard, strong anti-scouring damage capability and good waterproof performance.

In order to achieve the above purpose, the invention can adopt the following technical scheme:

the invention relates to a curing agent for a damming material of a check dam in a loess region, which consists of a powder curing component and a liquid waterproof component. Wherein the powder curing component comprises the following components:

65-75 parts of slag powder, 15-30 parts of cement, 5-25 parts of fly ash, 1-7 parts of synthetic fiber, 2-5 parts of calcium sulfate and 1-5 parts of calcium hydroxide.

In some embodiments, the slag powder is ground granulated blast furnace slag powder above grade S95.

In some embodiments, the cement is a portland or portland cement grade 42.5 or greater.

In some embodiments, the fly ash is obtained by grinding more than class F two-grade fly ash, and the fineness is more than 800 meshes.

In some embodiments, the synthetic fibers are PP, PVA, or PE fibers having a length of 5 to 10mm and an equivalent diameter of 20 to 50 μm.

And mixing the powder material in a high-speed mixer for 3-5 min, adding the synthetic fiber material, and mixing at a low speed for 2-3 min until the mixture is uniform.

Wherein the liquid waterproof composition comprises:

70-90 parts of emulsified PDMS polydimethylsiloxane, 5-20 parts of nano silicon dioxide solution and 1-5 parts of xanthan gum.

In some embodiments, the emulsified PDMS has a solid content of 30%, a viscosity of 100 to 350X 10 to E⁶m²/s。

In some embodiments, the nano-silica solution has a particle size of 20-50 nm and a solid content of 30%.

The preparation method of the liquid waterproof composition comprises the following steps:

and (3) stirring the materials in a slurry stirrer at a low speed for 3-5 min until the materials are uniform, thus obtaining the liquid waterproof component.

Applications of

In some embodiments, when in use, the powder material: 10-40% of loess: mixing uniformly 90-60, and then mixing the powder materials after stirring: uniformly spraying a liquid material in a ratio of 100: 3-8, intentionally stirring in the spraying process, additionally adding water to the optimal water content of the powder material in a compaction test, and then shaping.

Advantageous effects

Compared with the prior art, the invention has the following technical effects:

compared with the prior art, the gel material can be directly used for curing the loess without adding any additional gel material. In a performance test, the unconfined compressive strength of the solidified soil body can reach more than 5MPa, and the toughness and the crack resistance of the solidified soil body are improved through fibers, so that the high-strength and high-toughness solidified soil body material is formed. The prepared liquid waterproof component is adopted to enable the soil body to have hydrophobicity, so that a large amount of external moisture can be effectively prevented from permeating, and the loess collapsibility is reduced.

Detailed Description

The present invention is described in more detail below to facilitate an understanding of the present invention.

Those skilled in the art will recognize that: the chemical reactions described herein may be used to suitably prepare a number of other compounds of the invention, and other methods for preparing the compounds of the invention are considered to be within the scope of the invention. For example, the synthesis of those non-exemplified compounds according to the present invention can be successfully accomplished by those skilled in the art by modification, such as appropriate protection of interfering groups, by the use of other known reagents other than those described herein, or by some routine modification of the reaction conditions. In addition, the reactions disclosed herein or known reaction conditions are also recognized as being applicable to the preparation of other compounds of the present invention.

The curing agent for the damming material of the silt dam in the loess plateau area consists of a powder curing component and a liquid waterproof component. Wherein the powder curing component comprises the following components:

Wherein, the slag powder can adopt S95 level ground granulated blast furnace slag powder, and the quality meets the regulation of the current national standard of granulated blast furnace slag powder used in cement, mortar and concrete (GB/T18046); the cement can be ordinary Portland cement 42.5 cement, and the quality of the cement meets the regulations of the current national standard general Portland cement (GB/T175); the fly ash can be formed by grinding F-class secondary fly ash, the fineness of the fly ash is 1000 meshes, and the quality of the fly ash before grinding meets the regulation of the existing national standard fly ash for cement and concrete (GB/T1596); the synthetic fiber is PVA fiber, the length is 10mm, the equivalent diameter is 20 mu m, and other properties meet the regulations of the existing national standard synthetic fiber for cement concrete and mortar GB/T21120.

The specific process for preparing the powder curing composition comprises the following steps:

The liquid composition comprises the following components in parts by weight:

(1) The emulsified PDMS has a solid content of 30%, and a viscosity of 100-350 multiplied by 10-6 m²And s. It has the following general molecular structural formula

(2) The nano silicon dioxide solution has the particle size of 20-50 nm and the solid content of 30%.

The nanosilica solution may be commercially available or prepared as follows: the industrial silicon with Si more than or equal to 99 percent, Ca less than or equal to 0.02 percent, Al less than or equal to 0.27 percent, Fe less than or equal to 0.20 percent and other impurities less than or equal to 0.51 percent is ground and screened to prepare silicon powder, the silicon powder is slowly added into a reactor within 4 to 6 hours, sodium hydroxide or potassium hydroxide and lithium hydroxide are used as catalysts, distilled water is used as a dissolving medium, the reaction temperature is 60 to 97 ℃ under normal pressure, the reaction is completed within 4 to 6 hours, and a silicon dioxide solution with the concentration of 25 to 35 percent is prepared after filtering and decoloring.

(3) Commercially available xanthan gum, which is a complex polysaccharide produced by fermentation, has the following structural formula:

Examples of preparation of loess-molded sample

The loess is obtained from typical loess areas of Ulforest of Shaanxi province, and is matched with the curing agent of the embodiment of the invention to prepare a molded sample. The preparation method of the invention is adopted, wherein the compositions, compositions and proportions of the curing agents adopted in the examples are shown in the table.

TABLE 1

Coefficient of wet fall test

Loess has various degrees of collapsibility due to its unique engineering properties and structural characteristics. The method is directly related to the construction cost and safety risk of the engineering, so the method is always an important problem concerned by the geotechnical engineering industry. The loess collapse coefficient of the soil in western regions of China needs to be tested before construction of loess buildings in the western regions so as to ensure safety.

The loess collapsibility coefficient (coefficient of collapsibility of loess) is a mechanical parameter for evaluating the collapsibility of loess. The ratio of the height difference of the soil sample before and after soaking to the original height of the soil sample under a certain pressure.

According to the 4.3.2 th article of the building code of collapsible loess area (GB 50025-2018) in China, the collapsible coefficient deltas is calculated according to the following formula:

in the formula: h is_pKeeping the sample with natural water content and structure, and sinking to a stable height (mm) when pressurizing to a certain pressure;

h’_p-adding the stabilized height (mm) of the sample after pressing and sinking under the saturated condition of soaking;

h₀original height (mm) of the sample.

The test pressure for determining the coefficient of collapsibility deltas is determined according to the depth of the soil sample and the pressure of the substrate. Calculating the depth of the soil sample from the bottom surface of the foundation, and calculating from 1.5m below the ground when the elevation of the foundation is uncertain; the test pressure should be taken under the following conditions:

1. when the substrate pressure is less than 300kPa, applying 200kPa to a soil layer within 10m below the substrate, applying the saturated dead weight pressure of soil covering the soil layer from below 10m to the top surface of a non-collapsible loess layer;

2. when the base pressure is not less than 300kPa, the actual base pressure is preferably used, and when the saturated dead weight pressure of the upper covering soil is greater than the actual base pressure, the saturated dead weight pressure of the upper covering soil is applied;

3. for the newly piled loess with high compressibility, the pressure of (100-150) kPa is preferably applied to the soil layer within 5m below the substrate, and the pressure of 200kPa and the saturated dead weight pressure of the upper covering soil are respectively applied to the soil layer with the pressure of 5 m-10 m and the pressure of 10m below the substrate to the top surface of the non-collapsible loess layer.

Coefficient of Wet collapse of samples in inventive examples 1-5

After the curing agent samples of examples 1-5 were obtained, the curing agent samples were continuously used in loess areas to test their performance. Taking a plurality of loess in typical loess areas of Yulin of Shanxi, crushing the loess into 100 meshes, and airing for later use. According to the powder material: loess 18: 82, uniformly mixing. Spraying and adding 4% of liquid material, stirring uniformly, and adding a proper amount of water in the process to adjust to an optimal water content state. Preparing unconfined compressive strength samples and collapse coefficient test samples, and forming blank samples at the same time. The results of the experiments are shown in the following table.

TABLE 2

	Compressive strength MPa	Coefficient of wet sinking
			Example 1	6.3	0.017
Example 2	5.8	0.015
			Example 3	6.1	0.016
Examples4	5.3	0.011
			Example 5	5.9	0.013
Blank sample	1.2	0.042

After curing for 7 days, the unconfined compressive strength of the cured sample is up to 6.1MPa, and the unconfined compressive strength of a blank sample is 1.2 MPa; the coefficient of wet collapse of the cured sample was as low as 0.011 for the blank sample, 0.042. Therefore, the curing agent provided by the invention obviously improves the strength of the soil body and reduces the collapsibility of the soil body.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims

1. A curing agent for a damming material of a check dam in a loess area comprises a powder curing component and a liquid waterproof component:

wherein the powder curing component comprises the following components:

65-75 parts of slag powder, 15-30 parts of cement, 5-25 parts of fly ash, 1-7 parts of synthetic fiber, 2-5 parts of calcium sulfate and 1-5 parts of calcium hydroxide;

the synthetic fiber is a PP fiber, a PVA fiber or a PE fiber, the length is 5-10 mm, and the equivalent diameter is 20-50 μm;

wherein the liquid waterproof composition comprises:

70-90 parts of emulsified polydimethylsiloxane, 5-20 parts of nano silicon dioxide solution and 1-5 parts of xanthan gum;

the emulsified polydimethylsiloxane has the solid content of 30 percent and the viscosity (1.0-3.5) multiplied by 10^-4m²/s；

The nano silicon dioxide solution has the particle size of 20-50 nm and the solid content of 30%.

2. The curing agent according to claim 1, wherein the slag powder is ground granulated blast furnace slag powder of grade S95 or above.

3. The curing agent according to claim 1, wherein the cement is Portland or ordinary Portland cement with a grade of 42.5 or more.

4. The curing agent according to claim 1, wherein the fly ash is obtained by grinding more than class F two-grade fly ash, and the fineness of the fly ash is more than 800 meshes.

5. The use of the curing agent for the damming material of the silt dam in the loess area as set forth in claim 1 to 4, wherein the powder material is mixed in a high-speed mixer for 3 to 5min, and then the synthetic fiber material is added and mixed at a low speed for 2 to 3min until the mixture is uniform; stirring the components of the liquid waterproof composition in a slurry stirrer at a low speed for 3-5 min until the components are uniform, thus obtaining the liquid waterproof component;

according to the powder material: loess = 10-40: mixing uniformly 90-60, and then mixing the powder materials after stirring: uniformly spraying a liquid material according to the ratio of liquid =100: 3-8, intentionally stirring in the spraying process, additionally adding water to the optimal water content of the mixed powder material in a compaction test, and then shaping.