CN113025336A - Expansive soil ecological modifier - Google Patents

Abstract

The invention relates to a proportion and a preparation method of an expansive soil ecological modifier, wherein a stabilizer, an emulsifier, a coupling agent, an initiator, a plasticizer and a buffering agent are mainly added into three chemical raw materials of vinyl acetate, methyl methacrylate and vinyl versatate, and the expansive soil ecological modifier is generated through a series of chemical reactions such as dissolution, emulsification, coupling, polymerization and the like. The product is widely applied to a plurality of domestic expressways and railways, and has better economic benefit and social benefit.

Description

Expansive soil ecological modifier

Technical Field

The invention relates to a proportion and a preparation method of an expansive soil ecological modifier.

Background

The expansive soil is widely distributed in China, and the mineral composition of the expansive soil mainly comprises illite and montmorillonite and contains a small amount of kaolinite. The hydrophilic clay mineral can swell in water and shrink under water loss, and has obvious swelling and shrinking property, multiple crack property, super-consolidation property and strength weakening property. The accidents of sinking, slipping, longitudinal cracking, collapse and the like are easily caused. The mineral composition and structural form of the expansive soil make it have expansion and contraction characteristics, and the change of water content makes the characteristic show. The newly excavated expansive soil foundation and the side slope are influenced by factors such as rainwater, atmosphere, underground water, soil pressure and the like, so that the water content of the expansive soil is changed. Repeated swelling and shrinking results in loosening of the swelled soil body and the formation of many irregular cracks in the swelled soil body, which destroy the integrity of the soil body and make water invasion and water evaporation in the soil easier. The expansion and contraction deformation caused by the fluctuation of the water content of the soil body is repeated, and the crack is further expanded and developed towards the deep part of the soil layer, so that the strength of the soil body is greatly reduced, and a weathered layer is formed. The depth of the weathered layer is generally 1-1.2 m. Within the depth range of the weathering layer, the wet expansion and dry shrinkage effect of the soil body is obvious, and the cohesive force and the shear strength of the soil body are rapidly reduced, so that the atmospheric weathering layer is a direct guide layer for generating various foundation and side slope diseases, and has great harm to the stability of the foundation and the side slope, and the expansive soil atmospheric weathering layer is a main reason for harming engineering and is a key object for engineering protection and treatment. For the traditional disposal scheme of the expansive soil excavation side slope, the rigid protection in a fully-closed form is generally adopted. The main points are that: the main reason for the instability of the expansive soil slope is influenced by precipitation, when the soil absorbs water from an unsaturated state to a saturated state, the shear strength of the soil is gradually weakened from strong, and when the shear index value of the soil is attenuated along with the increase of the water content, the slope stability is gradually reduced until deformation damage is generated. Therefore, the slope is protected in a closed mode to prevent rainfall from being absorbed by unsaturated soil, and the method is mainly used for preventing and treating mortar rubble full pavements, protecting concrete hexagonal blocks full pavements, reinforcing the slope by soil nailing walls and the like. Practice proves that the rigid protection schemes have poor effect on treating the expansive soil. The expansion and shrinkage problems of the expansive soil body in the depth range influenced by the atmospheric weathering layer can not be fundamentally solved. Because the newly excavated slope surface of the expansive soil is influenced by various factors such as atmosphere, underground water, soil pressure change and the like, even if precipitation is not immersed, expansion and contraction can occur, certain deformation is inevitably generated, and new balance is achieved. Even if this deformation is not significant, it can be destructive to the rigid protective structure. Cracks are slowly formed, rainwater can infiltrate from the cracks, expansion and shrinkage deformation of the expansive soil are aggravated, and vicious circle is performed until chain damage is caused. The rigid protective structure also has the defects of glare, dry sound, incapability of reducing the ecological environment and the like. The expansive soil roadbed is treated by methods of replacing filling soil and doping lime, cement and the like in expansive soil roadbed filling materials, the lime solidification mechanism is the cementing action between hydrate of silicate and aluminum and particles, the cementing action is gradually dehydrated and the crystallization action of new minerals is carried out, so that the liquid limit is reduced, and the shear strength of a soil body is increased. Although the two methods have certain effects, through construction experience for many years, survey of a road which is already in traffic and indoor and outdoor tests, the reaction speed of lime, cement and soil is low, the strength of the generated hydrate is low, the durability is poor, the lime mixing amount is more than 8%, and the cement mixing amount is more than 6%, so that a certain effect can be achieved. And the materials need to be mixed evenly repeatedly during construction, the period is long, the working hours are consumed, the construction performance is poor, and the construction cost is high.

Disclosure of Invention

The expansive soil ecological modifier is characterized in that the components of the modifier are 100 parts of purified water, 1: 55-65 parts of vinyl acetate, and monomer 2: 6-10 parts of methyl methacrylate, 3 parts of monomer: 3-5 parts of ethylene versatate, stabilizer: 8-15 parts of polyvinyl alcohol, and an emulsifier: compounding 2-6 parts of nonylphenol polyoxyethylene ether/sodium dodecyl benzene sulfonate in a ratio of 1:1, wherein the coupling agent comprises the following components: KH560/KH570 are compounded in a ratio of 1:1 by 2-6 parts, and initiator: 1-5 parts of ammonium persulfate, and a plasticizer: 8-15 parts of dibutyl phthalate, and a buffering agent: 1-5 parts of sodium bicarbonate.

A preparation method of an expansive soil ecological modifier is characterized by comprising the following steps:

firstly, 100 parts of water and 8-15 parts of stabilizer are put into a stainless steel reaction kettle provided with devices for reflux condensation, stirring, heating and the like, the temperature is increased to 80-90 ℃, the mixture is fully stirred for 2-4 hours to be completely dissolved, then 2-6 parts of emulsifier are added, stirred and mixed uniformly, and the mixture is cooled to 70 ℃; secondly, 1/4 of three raw materials of 55-65 parts of monomer 1, 6-10 parts of monomer 2 and 3-5 parts of monomer 3 and 2-6 parts of coupling agent are put into a reaction kettle, and 1-5 parts of initiator and water are added according to the proportion of 1: 5, preparing aqueous solution, putting 1/2 initiator aqueous solution into a reaction kettle, fully stirring, controlling the temperature to be 65-70 ℃, reacting for 1-2 hours, and then adding the rest 1/2 initiator aqueous solution; thirdly, slowly dripping the remaining 3/4 of the three raw materials of the monomer 1, the monomer 2 and the monomer 3 into the reaction kettle within 4 hours, fully stirring and controlling the temperature to be 75-80 ℃, and then keeping the temperature to continue the reaction for 2 hours; step four, cooling the reaction mixture to 50 ℃, adding 8-15 parts of plasticizer into the reaction kettle, and adding 1-5 parts of buffering agent and water according to the weight ratio of 1: and preparing 10 components into an aqueous solution, adding the aqueous solution into a reaction kettle, fully stirring and cooling to room temperature to obtain the expansive soil ecological modifier.

The reaction equation is as follows:

drawings

FIG. 1 is a schematic process flow diagram.

Detailed Description

One of the specific embodiments is described below:

the Mongolian railway is distributed on expansive soil areas, and in order to ensure the safety and quality of engineering, the Mongolian railway is entrusted by Mongolian railway construction departments, and the expansive soil ecological modifier is adopted to carry out modification construction on cutting slopes of expansive soil sections and soil bodies of foundations.

Firstly, the expansive soil ecological modifier, water and lime are mixed according to the weight ratio of 1: 100: 5 fully stirring to prepare an aqueous solution, uniformly spraying the prepared aqueous solution of the expansive soil ecological modifier on the surface of the expansive soil body, and infiltrating into the soil body by an infiltration method. After the first spraying is finished, the soil body is dried, and then the next spraying is carried out by the same method, and the spraying times of the expansive soil ecological modifier aqueous solution are preferably three times under the common condition. After the modification construction is finished, in order to distinguish the modification effects at different depths, three modified soil samples with the depths of 0.0-0.3 m, 0.3-0.6 m and 0.6-1.0 m and one undisturbed soil sample are delivered to a detection mechanism with CMA quality for detection, and the detection result is detailed as follows:

comparative table for swelling test results

The detection results in the table show that the free expansion rates of three modified soil samples at different depths are all below 40%, the montmorillonite content is all below 7%, the cation exchange capacity is all below 170 mmol/kg, and according to the discrimination standard of the expansive soil, the modified soil bodies are all non-expansive soil, so that the aim of modifying the expansive soil into the non-expansive soil is fulfilled. The expansive soil ecological modifier produced by our company is widely applied to projects such as highways, railways and the like so far, and the modified soil body has good performance and stable effect and is deeply praised by users.

Claims (2)

1. The expansive soil ecological modifier is characterized in that the components of the modifier are 100 parts of purified water, 1: 55-65 parts of vinyl acetate, and monomer 2: 6-10 parts of methyl methacrylate, 3 parts of monomer: 3-5 parts of ethylene versatate, stabilizer: 8-15 parts of polyvinyl alcohol, and an emulsifier: compounding 2-6 parts of nonylphenol polyoxyethylene ether/sodium dodecyl benzene sulfonate in a ratio of 1:1, wherein the coupling agent comprises the following components: KH560/KH570 are compounded in a ratio of 1:1 by 2-6 parts, and initiator: 1-5 parts of ammonium persulfate, and a plasticizer: 8-15 parts of dibutyl phthalate, and a buffering agent: 1-5 parts of sodium bicarbonate.

2. A preparation method of an expansive soil ecological modifier is characterized by comprising the following steps:

firstly, 100 parts of water and 8-15 parts of stabilizer are put into a stainless steel reaction kettle provided with devices for reflux condensation, stirring, heating and the like, the temperature is increased to 80-90 ℃, the mixture is fully stirred for 2-4 hours to be completely dissolved, then 2-6 parts of emulsifier are added, stirred and mixed uniformly, and the mixture is cooled to 70 ℃; secondly, 1/4 of three raw materials of 55-65 parts of monomer 1, 6-10 parts of monomer 2 and 3-5 parts of monomer 3 and 2-6 parts of coupling agent are put into a reaction kettle, and 1-5 parts of initiator and water are added according to the proportion of 1: 5, preparing aqueous solution, putting 1/2 initiator aqueous solution into a reaction kettle, fully stirring, controlling the temperature to be 65-70 ℃, reacting for 1-2 hours, and then adding the rest 1/2 initiator aqueous solution; thirdly, slowly dripping the remaining 3/4 of the three raw materials of the monomer 1, the monomer 2 and the monomer 3 into the reaction kettle within 4 hours, fully stirring and controlling the temperature to be 75-80 ℃, and then keeping the temperature to continue the reaction for 2 hours; step four, cooling the reaction mixture to 50 ℃, adding 8-15 parts of plasticizer into the reaction kettle, and adding 1-5 parts of buffering agent and water according to the weight ratio of 1: and preparing 10 components into an aqueous solution, adding the aqueous solution into a reaction kettle, fully stirring and cooling to room temperature to obtain the expansive soil ecological modifier.

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