阅读说明：本技术 一种软弱地基的加固方法 (Method for reinforcing soft foundation ) 是由 林艳芬 于 2019-10-12 设计创作，主要内容包括：本发明涉及地基处理技术领域,具体涉及一种软弱地基的加固方法。本发明先在土坑底部铺垫一层碎石,接着以废弃猪毛为原料,得到功能添加剂,随后将挖出的软弱地基土和硅酸盐水泥、生石灰以及水预混后和功能添加剂搅拌混合高速打浆,得到加固浆料,最后将其注入预处理土坑中,养护固化后即可,本发明中猪毛蛋白在高速打浆的过程中具有良好的起泡能力,可促进泡沫的稳定性,避免由于土体重度过大造成的软弱地基沉降的现象,本发明加入的功能添加剂中还含有部分未溶解的猪毛角蛋白,起到分散地基土受到冲击时应力的作用,而功能填料还具有生物矿化作用,极大的增强了土体的力学强度,使路基承载力显著提高,具有广阔的应用前景。(The invention relates to the technical field of foundation treatment, in particular to a method for reinforcing a soft foundation. The invention firstly lays a layer of broken stone at the bottom of a soil pit, then uses waste pig hair as raw material to obtain functional additive, then mixes the dug-out soft foundation soil, silicate cement, quicklime and water in advance, then stirs, mixes and pulpes with the functional additive at high speed to obtain reinforced slurry, finally injects the reinforced slurry into a pretreated soil pit, the pig hair protein has good foaming capacity in the high-speed pulping process after curing and solidification, can promote the stability of foam and avoid the phenomenon of soft foundation settlement caused by over-heavy soil body, the functional additive added in the invention also contains part of undissolved pig hair keratin, plays the role of dispersing stress when the foundation soil is impacted, the functional filler also has a biological mineralization effect, greatly enhances the mechanical strength of the soil body, obviously improves the bearing capacity of the roadbed, and has wide application prospect.)

1. A method for reinforcing a soft foundation is characterized by comprising the following concrete reinforcing steps:

injecting self-made reinforcement slurry into the dug pretreated soil pit until the reinforcement slurry is flush with the upper edge of the soil pit, covering the surface of the soil pit with a film after grouting is finished, standing and maintaining, and removing the film on the surface after maintenance is finished, so that reinforcement of the soft foundation can be finished;

the digging and building steps of the pretreated pit are as follows:

digging soil pits on the surface of a soft foundation to be reinforced, keeping the vertical distance between two adjacent sides of two adjacent soil pits at 30cm, piling the dug soft foundation soil for later use, and spreading a layer of crushed stone at the bottom of each soil pit to obtain a pretreated soil pit;

the preparation steps of the self-made reinforcing material are as follows:

mixing the premix and the functional additive, putting the mixture into a high-speed pulping machine, pulping at a high speed of 800-900 r/min for 15-20 min, and obtaining the self-made reinforcement slurry after pulping;

the preparation steps of the premix are as follows:

weighing the spare soft foundation soil, Portland cement, quicklime and water, mixing, putting into a mixer, and mixing and stirring at a rotating speed of 100-200 r/min for 30-40 min to obtain a premix;

the preparation steps of the functional additive are as follows:

(1) mixing the waste pig hair with hydrochloric acid with the concentration of 0.5mol/L, putting the mixture into a reaction kettle, soaking for 3-5 hours, adjusting the pH to be neutral by using a sodium hydroxide solution with the concentration of 1mol/L after soaking is finished, adding sodium bisulfite into the reaction kettle, and continuing soaking for 3-5 hours at the temperature of 60-70 ℃ to obtain a soaked substance;

(2) and mixing the soaked substance with a sodium hydroxide solution with the concentration of 0.5mol/L, putting the mixture into a microwave oscillator, carrying out microwave oscillation reaction for 1-2 hours at the temperature of 70-80 ℃ and with the power of 200-300W, and obtaining the functional additive after the reaction is finished.

2. The method for reinforcing a weak foundation according to claim 1, wherein: in the specific reinforcing step, the standing and curing time is preferably 1-2 weeks.

3. The method for reinforcing a weak foundation according to claim 1, wherein: in the digging and building step of the pretreated pit, the side length of the dug pit is 2m, and the depth is 50 cm.

4. The method for reinforcing a weak foundation according to claim 1, wherein: in the digging and building step of the pre-treatment soil pit, the spreading thickness of the broken stone blocks is 10 cm.

5. The method for reinforcing a weak foundation according to claim 1, wherein: in the step of preparing the self-made reinforcing material, the mass ratio of the premix to the functional additive is 5: 1.

6. The method for reinforcing a weak foundation according to claim 1, wherein: in the preparation step of the premix, 40-50 parts of spare soft foundation soil, 20-30 parts of Portland cement, 15-20 parts of quicklime and 100-200 parts of water are counted in parts by weight.

7. The method for reinforcing a weak foundation according to claim 1, wherein: in the step (1) of preparing the functional additive, the mass ratio of the waste pig hair to the hydrochloric acid with the concentration of 0.5mol/L is 1: 10.

8. The method for reinforcing a weak foundation according to claim 1, wherein: in the step (1) of preparing the functional additive, the adding amount of the sodium bisulfite is 10 percent of the mass of the waste pig hair.

9. The method for reinforcing a weak foundation according to claim 1, wherein: in the preparation step (2) of the functional additive, the mass ratio of the soaked substance to the sodium hydroxide solution with the concentration of 0.5mol/L is 1: 10.

Technical Field

The invention relates to the technical field of foundation treatment, in particular to a method for reinforcing a soft foundation.

Background

In recent years, dredged soil is often used as filling soil for reclamation of land from sea, and after the dredged soil is filled to a construction site by mechanical blowing, ultra-weak soil is often formed on the surface. The ultra-soft soil has the characteristics of high water content, large compressibility, low strength and bearing capacity and the like, and therefore, the foundation must be reinforced before any use, and the land obtained by land reclamation from sea can be used as a construction land.

At present, the traditional soft foundation reinforcement treatment method mainly comprises the following steps: a dynamic compaction replacement method, an overload prepressing method, a pile body reinforcing method and the like. In the dynamic compaction replacement process, mechanisms such as dynamic compaction, replacement into piers, drainage consolidation and the like complement each other to form a complex integral reinforcing structure. The construction method has the characteristics of simple construction process, economy and convenience, and capability of reinforcing the soft foundation by dynamic compaction replacement and drainage consolidation. At present, the dynamic compaction replacement method is mainly used for soft soil layers with high water content, large pore ratio, large compressibility and low strength value in coastal areas, and is lack of application to soft foundations in carbonate rock areas; the pile body reinforcing method is to form a composite foundation together with the soil body between piles to raise the comprehensive bearing capacity and settlement controlling capacity of the foundation. Has quick effect, but needs to rely on additional stress to influence one or more better natural foundation bearing layers in the depth range. In addition, the soil body between piles cannot be improved continuously along with the time, and the possibility of attenuation of the reinforcing effect can also occur in the later period; the overload preloading method can effectively solve the problem of settlement of soft foundation, but the required construction period is long, and the overload preloading method is not suitable for projects with construction period requirements.

Because the density of the soft foundation soil is high, the soil is heavy, the subgrade settlement is easy to occur, and the mechanical property and the bearing capacity of the soft foundation soil are low, the soft foundation reinforcing method which is low in cost, high in reliability, easy to adjust and control, wide in adaptability and good in technical economy needs to be provided urgently.

Disclosure of Invention

The invention mainly solves the technical problems of large density, heavy soil, easy subgrade settlement, low mechanical property and poor bearing capacity of the existing weak foundation soil, and provides a method for reinforcing the weak foundation.

In order to solve the technical problems, the technical scheme adopted by the invention is as follows:

the concrete reinforcing steps of the soft foundation are as follows:

injecting self-made reinforcement slurry into the dug pretreated soil pit until the reinforcement slurry is flush with the upper edge of the soil pit, covering the surface of the soil pit with a film after grouting is finished, standing and maintaining, and removing the film on the surface after maintenance is finished, so that reinforcement of the soft foundation can be finished;

the digging and building steps of the pre-treated pit are as follows:

digging soil pits on the surface of a soft foundation to be reinforced, keeping the vertical distance between two adjacent sides of two adjacent soil pits at 30cm, piling the dug soft foundation soil for later use, and spreading a layer of crushed stone at the bottom of each soil pit to obtain a pretreated soil pit;

the preparation steps of the self-made reinforcing material are as follows:

mixing the premix and the functional additive, putting the mixture into a high-speed pulping machine, pulping at a high speed of 800-900 r/min for 15-20 min, and obtaining the self-made reinforcement slurry after pulping;

the preparation steps of the premix are as follows:

weighing the spare soft foundation soil, Portland cement, quicklime and water, mixing, putting into a mixer, and mixing and stirring at a rotating speed of 100-200 r/min for 30-40 min to obtain a premix;

the preparation steps of the functional additive are as follows:

(1) mixing the waste pig hair with hydrochloric acid with the concentration of 0.5mol/L, putting the mixture into a reaction kettle, soaking for 3-5 hours, adjusting the pH to be neutral by using a sodium hydroxide solution with the concentration of 1mol/L after soaking is finished, adding sodium bisulfite into the reaction kettle, and continuing soaking for 3-5 hours at the temperature of 60-70 ℃ to obtain a soaked substance;

(2) and mixing the soaked substance with a sodium hydroxide solution with the concentration of 0.5mol/L, putting the mixture into a microwave oscillator, carrying out microwave oscillation reaction for 1-2 hours at the temperature of 70-80 ℃ and with the power of 200-300W, and obtaining the functional additive after the reaction is finished.

In the concrete reinforcing step, the standing and curing time is preferably 1-2 weeks.

In the digging and building step of the pre-treated pit, the side length of the dug pit is 2m, and the depth is 50 cm.

In the digging and building step of the pre-treatment soil pit, the spreading thickness of the broken stone blocks is 10 cm.

In the preparation step of the self-made reinforcing material, the mass ratio of the premix to the functional additive is 5: 1.

In the preparation step of the premix, 40-50 parts by weight of the spare soft foundation soil, 20-30 parts by weight of Portland cement, 15-20 parts by weight of quicklime and 100-200 parts by weight of water are counted.

In the step (1) of preparing the functional additive, the mass ratio of the waste pig hair to the hydrochloric acid with the concentration of 0.5mol/L is 1: 10.

In the step (1) of preparing the functional additive, the adding amount of the sodium bisulfite is 10 percent of the mass of the waste pig hair.

In the preparation step (2) of the functional additive, the mass ratio of the soaked substance to the sodium hydroxide solution with the concentration of 0.5mol/L is 1: 10.

The beneficial technical effects of the invention are as follows:

(1) digging a pit on the surface of a soft foundation to be reinforced, paving a layer of crushed stone at the bottom of the pit to obtain a pretreated pit, then taking waste pig hair as a raw material, treating the pig hair with acid and sodium bisulfite, then dipping the pig hair in alkali liquor microwave to obtain a functional additive, then premixing the dug soft foundation soil, portland cement, quicklime and water, stirring and mixing the premixed material with the functional additive at a high speed for pulping to obtain a reinforced slurry, finally injecting the reinforced slurry into the dug pretreated pit, curing and solidifying to finish the reinforcement of the soft foundation The quick lime and the water are premixed and then stirred and mixed with the functional additive to be pulped at a high speed to obtain reinforced slurry, because the number of disulfide bonds in the pig hair protein is large, the flexibility is good, and the amphipathy is obvious, the foaming capacity is good in the high-speed pulping process, the protein colloid viscosity is high, part of peptide chains can stretch on a gas-liquid interface to form a two-dimensional protective network, the mechanical strength of a foam interface membrane is increased, the stability of foam can be promoted, abundant micro air holes are formed in the reinforced slurry, the density of a reinforced soil body is reduced, the gravity of the reinforced soil is reduced, and the phenomenon of soft foundation settlement caused by the over-heavy soil body can be avoided;

(2) the functional additive added in the invention also contains partial undissolved pig hair keratin which has stable property and high mechanical strength, the addition of the keratin can form a physical reticular cross-linked structure in a reinforced soil body and is used as a stress conduction path to play a role of stress when dispersed foundation soil is impacted, the impact resistance bearing performance of a soft foundation is improved, meanwhile, when the foundation is subjected to temperature difference shrinkage, the toughness tensile strength is provided, the mechanical performance of the foundation is improved, and the functional filler also has a biomineralization function, wherein the insoluble pig hair keratin can become a framework or a template for crystal nucleation and growth, and polar groups of soluble protein molecular side chains interact with calcium ions in lime milk through coordination, static electricity and other functions, so that calcium attracts carbonate ions, and further attracts more calcium ions along with the aggregation of the carbonate ions, when the ion concentration is increased to form a nucleation point, the crystal growth is regulated and controlled by controlling the migration rate of ions, so that the micro-morphology of the calcium carbonate is influenced, the regular rhombohedral calcite crystals are formed, the mechanical strength of a soil body is greatly enhanced, the roadbed bearing capacity is obviously improved, and the method has a wide application prospect.

Detailed Description

Digging soil pits with the side length of 2m and the depth of 50cm on the surface of a soft foundation to be reinforced, keeping the vertical distance between two adjacent sides of two adjacent soil pits to be 30cm, piling up the dug soft foundation soil for later use, and spreading a layer of crushed stone with the thickness of 10cm at the bottom of each soil pit to obtain a pretreated soil pit; mixing the waste pig hair and hydrochloric acid with the concentration of 0.5mol/L according to the mass ratio of 1:10, putting the mixture into a reaction kettle, soaking for 3-5 hours, adjusting the pH to be neutral by using a sodium hydroxide solution with the concentration of 1mol/L after soaking is finished, adding sodium bisulfite with the mass of 10% of the waste pig hair into the reaction kettle, and continuously soaking for 3-5 hours at the temperature of 60-70 ℃ to obtain a soaked substance; mixing the soaked substance with a sodium hydroxide solution with the concentration of 0.5mol/L according to the mass ratio of 1:10, putting the mixture into a microwave oscillator, carrying out microwave oscillation reaction for 1-2 hours at the temperature of 70-80 ℃ and with the power of 200-300W, and obtaining a functional additive for later use after the reaction is finished; weighing 40-50 parts by weight of standby soft foundation soil, 20-30 parts by weight of portland cement, 15-20 parts by weight of quicklime and 100-200 parts by weight of water, mixing, putting into a mixer, and mixing and stirring at the rotating speed of 100-200 r/min for 30-40 min to obtain a premix; mixing the premix and the standby functional additive according to the mass ratio of 5:1, putting the mixture into a high-speed pulping machine, pulping at a high speed of 800-900 r/min for 15-20 min, and obtaining self-made reinforcement slurry after pulping; and (3) injecting the self-made reinforcing slurry into the dug pretreated soil pit until the self-made reinforcing slurry is flush with the upper edge of the soil pit, covering the surface of the soil pit with a film after grouting is finished, standing and curing for 1-2 weeks, and removing the film on the surface after curing is finished, so that the reinforcement of the soft foundation can be completed.

Preparation of a pretreated soil pit: digging soil pits with the side length of 2m and the depth of 50cm on the surface of a soft foundation to be reinforced, keeping the vertical distance between two adjacent sides of two adjacent soil pits to be 30cm, piling up the dug soft foundation soil for later use, and spreading a layer of crushed stones with the thickness of 10cm at the bottom of each soil pit to obtain a pretreated soil pit.

Preparation of the soak: mixing the waste pig hair and hydrochloric acid with the concentration of 0.5mol/L according to the mass ratio of 1:10, putting the mixture into a reaction kettle, soaking for 3 hours, adjusting the pH to be neutral by using sodium hydroxide solution with the concentration of 1mol/L after soaking is finished, adding sodium bisulfite with the mass of 10% of the waste pig hair into the reaction kettle, and continuing soaking for 3 hours at the temperature of 60 ℃ to obtain a soaked substance.

Preparation of functional additive: mixing the soaked substance with 0.5mol/L sodium hydroxide solution according to the mass ratio of 1:10, placing into a microwave oscillator, carrying out microwave oscillation reaction at 70 ℃ for 1h with the power of 200W, and obtaining the functional additive after the reaction is finished for later use.

Preparation of premix: weighing 40 parts by weight of standby soft foundation soil, 20 parts by weight of Portland cement, 15 parts by weight of quicklime and 100 parts by weight of water, mixing, putting into a mixer, and mixing and stirring at the rotating speed of 100r/min for 30min to obtain the premix.

Preparing self-made reinforcing slurry: and mixing the premix and the standby functional additive according to the mass ratio of 5:1, putting the mixture into a high-speed pulping machine, pulping at a high speed of 800r/min for 15min, and obtaining the self-made reinforcement slurry after pulping.

Preparing the reinforcement of the soft foundation: and (3) injecting the self-made reinforcing slurry into the dug pretreated soil pit until the self-made reinforcing slurry is flush with the upper edge of the soil pit, covering the surface of the soil pit with a film after grouting is finished, standing and curing for 1 week, and removing the film on the surface after curing is finished, so that the reinforcement of the soft foundation can be completed.

Preparation of a pretreated soil pit: digging soil pits with the side length of 2m and the depth of 50cm on the surface of a soft foundation to be reinforced, keeping the vertical distance between two adjacent sides of two adjacent soil pits to be 30cm, piling up the dug soft foundation soil for later use, and spreading a layer of crushed stones with the thickness of 10cm at the bottom of each soil pit to obtain a pretreated soil pit.

Preparation of the soak: mixing the waste pig hair and hydrochloric acid with the concentration of 0.5mol/L according to the mass ratio of 1:10, putting the mixture into a reaction kettle, soaking for 4 hours, adjusting the pH to be neutral by using sodium hydroxide solution with the concentration of 1mol/L after soaking is finished, adding sodium bisulfite with the mass of 10% of the waste pig hair into the reaction kettle, and continuing soaking for 4 hours at 65 ℃ to obtain a soaked substance.

Preparation of functional additive: mixing the soaked substance with 0.5mol/L sodium hydroxide solution according to the mass ratio of 1:10, placing the mixture into a microwave oscillator, carrying out microwave oscillation reaction for 1h at 75 ℃ with the power of 250W, and obtaining the functional additive after the reaction is finished for later use.

Preparation of premix: weighing 45 parts by weight of standby soft foundation soil, 25 parts by weight of portland cement, 17 parts by weight of quicklime and 150 parts by weight of water, mixing and then putting into a mixer, and mixing and stirring at the rotating speed of 150r/min for 35min to obtain the premix.

Preparing self-made reinforcing slurry: and mixing the premix and the standby functional additive according to the mass ratio of 5:1, putting the mixture into a high-speed pulping machine, pulping at the high speed of 850r/min for 17min, and obtaining the self-made reinforcement slurry after pulping.

Preparing the reinforcement of the soft foundation: and (3) injecting the self-made reinforcing slurry into the dug pretreated soil pit until the self-made reinforcing slurry is flush with the upper edge of the soil pit, covering the surface of the soil pit with a film after grouting is finished, standing and curing for 1 week, and removing the film on the surface after curing is finished, so that the reinforcement of the soft foundation can be completed.

Preparation of a pretreated soil pit: digging soil pits with the side length of 2m and the depth of 50cm on the surface of a soft foundation to be reinforced, keeping the vertical distance between two adjacent sides of two adjacent soil pits to be 30cm, piling up the dug soft foundation soil for later use, and spreading a layer of crushed stones with the thickness of 10cm at the bottom of each soil pit to obtain a pretreated soil pit.

Preparation of the soak: mixing the waste pig hair and hydrochloric acid with the concentration of 0.5mol/L according to the mass ratio of 1:10, putting the mixture into a reaction kettle, soaking for 5 hours, adjusting the pH to be neutral by using sodium hydroxide solution with the concentration of 1mol/L after soaking is finished, adding sodium bisulfite with the mass of 10% of the waste pig hair into the reaction kettle, and continuing soaking for 5 hours at 70 ℃ to obtain a soaked substance.

Preparation of functional additive: mixing the soaked substance with 0.5mol/L sodium hydroxide solution according to the mass ratio of 1:10, placing into a microwave oscillator, carrying out microwave oscillation reaction at 80 ℃ with the power of 300W for 2h, and obtaining the functional additive after the reaction is finished for later use.

Preparation of premix: weighing 50 parts by weight of standby soft foundation soil, 30 parts by weight of Portland cement, 20 parts by weight of quicklime and 200 parts by weight of water, mixing, putting into a mixer, and mixing and stirring at the rotating speed of 200r/min for 40min to obtain the premix.

Preparing self-made reinforcing slurry: and mixing the premix and the standby functional additive according to the mass ratio of 5:1, putting the mixture into a high-speed pulping machine, pulping at a high speed of 900r/min for 20min, and obtaining the self-made reinforcement slurry after pulping.

Preparing the reinforcement of the soft foundation: and (3) injecting the self-made reinforcing slurry into the dug pretreated soil pit until the self-made reinforcing slurry is flush with the upper edge of the soil pit, covering the surface of the soil pit with a film after grouting is finished, standing and curing for 2 weeks, and removing the film on the surface after curing is finished, so that the reinforcement of the soft foundation can be completed.

Comparative example 1: the procedure was essentially the same as in example 1, except that no soak was added.

Comparative example 2: the procedure was essentially the same as in example 2, except that no premix was added.

Comparative example 3: a method for reinforcing a soft foundation provided by a company in Shanghai.

The method for reinforcing the soft foundation provided by the invention is compared with the method provided by the comparative example, and the detection results are shown in table 1:

the dredger fill is made into cubic test blocks with the size of 70mm multiplied by 70mm, and the test blocks are respectively detected before reinforcing and after reinforcing.

The shear strength test presses the cross plate head into the soft soil at the bottom of the hole from the drill hole, rotates at a uniform speed, and measures the torque required by the rotation of the cross plate head through a certain measuring system until the soil body is destroyed, thereby calculating the shear strength of the unearthed soil.

TABLE 1 measurement results of Properties

As can be seen from the data in Table 1, the reinforcing method for the soft foundation provided by the invention has the advantages of simple reinforcing steps, easy operation, low cost, obvious reinforcing effect, capability of effectively resisting flood, strong rainfall erosion and heavy object rolling, capability of improving the surrounding environment and wide application prospect.