1. The cement modified soil roadbed filling process is characterized by comprising the following steps:

s1, cleaning and leveling the site;

s2, filling a protective layer for solidifying sulfate ions, and rolling the protective layer, wherein the compaction thickness of the protective layer is 10-12 cm;

s3, paving the cement modified soil, wherein the loose paving thickness is 25-35 cm;

s4, rolling the cement modified soil, compacting to 18-28 cm in thickness, and controlling the water content to be 12.3% -15.6% to obtain a cement modified soil layer;

and S5, curing for 7-11 days to obtain the roadbed.

2. A cement modified soil roadbed filling process as claimed in claim 1, wherein said protective layer includes filler and a plurality of cured cloths, said cured cloths being geotextiles impregnated with soluble calcium salt.

3. The process of claim 2, wherein the curing cloths are arranged in the filler along the length direction of the foundation and are sequentially connected end to end.

4. A cement modified soil roadbed filling process as claimed in claim 2, wherein said filler includes river sand and broken stones.

5. The process of claim 2, wherein in step S2, a reverse osmosis membrane is laid after the protective layer is rolled.

6. The cement modified soil roadbed filling process of claim 1, wherein the preparation method of the cement modified soil is as follows: uniformly mixing 91.5-93.8 parts by weight of soil, 6-8 parts by weight of cement and 0.2-0.4 part by weight of composite fiber, wherein the composite fiber takes spandex filaments as a core and is woven by wrapping chopped glass fibers, and the weight ratio of the spandex filaments to the chopped glass fibers is 1: 1; then adding water and continuously stirring until the mixture is uniform to obtain the cement modified soil, wherein the water content of the cement modified soil is 16-18%.

7. The process of claim 1, wherein the site is cleaned and leveled in S1, and then a plurality of filling areas are evenly divided for the site, and then the filling areas are filled by adopting the processes of S2-S5.

8. The process of claim 7 wherein joints between said zones are filled and rolled by lapping to maintain close joints between said zones.

Background

The cement modified soil is a ground material prepared by mixing and stirring raw materials such as soil, cement, water and the like according to a proper proportion, can effectively improve the compression resistance of a soil body and reduce the deformation of the ground soil, and is widely applied to projects such as foundation reinforcement, dam construction, road base treatment and the like.

With the increasingly wide application of the cement modified soil, the cement modified soil inevitably meets a corrosive environment in the application, for example, in a south ionic rare earth production place, many traffic engineering projects adopting the cement modified soil as a main road base material cross a rare earth mine area, while the south ionic rare earth mining process mainly adopts an ammonium sulfate solution to leach rare earth elements, but the ammonium sulfate cannot be completely recovered after use, and a part of the ammonium sulfate remains in a foundation. After the subgrade is filled, if the subgrade is rainy, rainwater permeates into the foundation along the subgrade structure gradually, ammonium sulfate releases sulfate ions under the dissolving action of the rainwater, the sulfate ions migrate into the cement modified soil structure, the cement modified soil is easy to corrode, the strength of the cement modified soil is reduced, and the subgrade filling quality is reduced.

Disclosure of Invention

In order to improve the strength of the cement modified soil and further improve the roadbed filling quality, the application provides a cement modified soil roadbed filling process.

The cement modified soil roadbed filling process adopts the following technical scheme:

a cement modified soil roadbed filling process comprises the following steps:

s1, cleaning and leveling the site;

s2, filling a protective layer for solidifying sulfate ions, and rolling the protective layer, wherein the compaction thickness of the protective layer is 10-12 cm;

s3, paving the cement modified soil, wherein the loose paving thickness is 25-35 cm;

s4, rolling the cement modified soil, compacting to 18-28 cm in thickness, and controlling the water content to be 12.3% -15.6% to obtain a cement modified soil layer;

and S5, curing for 7-11 days to obtain the roadbed.

By adopting the technical scheme, the field is firstly cleaned and leveled, so that the field is kept clean and leveled, and the condition that impurities are doped in the roadbed to influence the stability of the roadbed is reduced. And then filling and rolling a protective layer, wherein the protective layer can solidify sulfate ions and reduce the migration condition of the sulfate ions in the roadbed. And paving the cement modified soil, rolling the cement modified soil, and maintaining to finish the filling process of the cement modified soil roadbed. The filling of the protective layer can reduce the damage of sulfate ions to the strength of the cement modified soil, thereby obtaining the effect of improving the strength of the cement modified soil and improving the filling quality of the roadbed.

Optionally, the protective layer comprises a filler and a plurality of pieces of solidified cloth, and the solidified cloth is geotextile impregnated with soluble calcium salt.

Through adopting above-mentioned technical scheme, the solidification cloth sets up in the filler for the geotechnological cloth that has soluble calcium salt of flooding, and when rainwater infiltration protective layer, soluble calcium salt dissolves production calcium ion on geotechnological cloth, can solidify the sulfate radical ion of migration, reduces sulfate radical ion's continuation migration to reduce the sulfate radical ion and get into in the modified soil of cement and destroy the condition of the modified soil intensity of cement. Sulfate ions and calcium ions are combined to generate calcium sulfate, the calcium sulfate is adsorbed on the filler, gaps among the filler are filled, a certain reinforcing effect can be achieved on the protective layer, and then the strength of the cement modified soil is improved, so that the effect of improving the filling quality of the roadbed is achieved.

Optionally, each of the curing cloths is arranged in the filler along the length direction of the foundation and is sequentially connected end to end.

Through adopting above-mentioned technical scheme, solidification cloth end to end connection can make sulfate radical ion contact with solidification cloth more, reduces the condition that sulfate radical ion migrated the protective layer to a great extent, further improves the solidification effect to sulfate radical ion.

Optionally, the filler comprises river sand and crushed stone.

By adopting the technical scheme, the broken stone and the river sand are used as the filler, so that the strength supporting effect can be achieved, the migration situation of sulfate ions can be further reduced by staggered filling formed by different particle sizes of the broken stone and the river sand, and the damage of the sulfate ions to the cement modified soil is reduced.

Optionally, in S2, a reverse osmosis membrane is laid after the protective layer is rolled.

Through adopting above-mentioned technical scheme, because reverse osmosis membrane's setting, the rainwater can permeate cement modified soil and make soluble calcium salt dissolve in getting into the protective layer through reverse osmosis membrane, produces calcium ion and solidifies the sulfate radical ion, and during sulfate radical ion can't permeate reverse osmosis membrane got into cement modified soil simultaneously, effectively reduced the destruction of sulfate radical ion to cement modified soil intensity, improved the intensity of cement modified soil, consequently, obtained the effect that improves the filling quality of road bed.

Optionally, the preparation method of the cement modified soil comprises the following steps: uniformly mixing 91.5-93.8 parts by weight of soil, 6-8 parts by weight of cement and 0.2-0.4 part by weight of composite fiber, wherein the composite fiber takes spandex filaments as a core and is woven by wrapping chopped glass fibers, and the weight ratio of the spandex filaments to the chopped glass fibers is 1: 1; then adding water and continuously stirring until the mixture is uniform to obtain the cement modified soil, wherein the water content of the cement modified soil is 16-18%.

By adopting the technical scheme, the composite fiber which is woven by taking the spandex filament as the core and wrapping the chopped glass fiber has better elasticity and tensile strength, the composite fiber is mixed with soil and cement, water is added, and the mixture is mixed to prepare the cement modified soil.

Optionally, after the yard is cleaned and leveled in S1, a plurality of filling areas are averagely divided for the yard, and then the filling areas are filled by adopting the processes from S2 to S5.

By adopting the technical scheme, the quality of each filling area can be controlled and adjusted in time by adopting the partition filling method, so that the filling quality of the roadbed is improved.

Optionally, joints between filling areas are filled and rolled by using a lapping method so as to keep the joints between the filling areas tightly connected.

Through adopting above-mentioned technical scheme, adopt the overlap joint method to fill and roll between each filling district, can make the seam crossing between each filling district link up closely, help improving the joint strength between each filling district, consequently, obtain the effect that improves the filling quality of road bed.

In summary, the present application has the following beneficial effects:

1. because this application fills out the protective layer earlier, can solidify the sulfate ion, reduce the sulfate ion migration condition in the road bed, reduce the sulfate ion to the destruction of the intensity of cement modified soil, consequently, obtain the intensity that improves cement modified soil to improve the effect of the filling quality of road bed.

2. Through the quality control of each step technology in whole filling process in this application, like protective layer compaction thickness, the water content of the modified soil of cement after mixing, modified soil compaction thickness of cement etc. can effectively improve the holistic filling quality of road bed.

3. This application is through reverse osmosis membrane's setting, and the rainwater can permeate cement modified soil and make soluble calcium salt dissolve in getting into the protective layer through reverse osmosis membrane, produces calcium ion and solidifies the sulfate radical ion, and during sulfate radical ion can't see through reverse osmosis membrane entering cement modified soil simultaneously, effectively reduced the destruction of sulfate radical ion to cement modified soil intensity, improved the intensity of cement modified soil, consequently, obtained the effect that improves the filling quality of road bed.

Detailed Description

The present application will be described in further detail with reference to examples. The special description is as follows: the following examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer, and the starting materials used in the following examples were obtained from ordinary commercial sources unless otherwise specified.

The chopped glass fibers had a length of 6 mm.

The gauge of the spandex filament is 154 dtex.

The cement is P.O 42.5.5 ordinary portland cement.

The river sand is 8-16 meshes.

The particle size of the broken stone is 10-20 mm.

The water is industrial water.

Preparation example

Preparation example 1

Taking 500kg of spandex filament and 500kg of chopped glass fiber, and preparing the composite fiber taking the spandex filament as a core and coated with the chopped glass fiber by a core-spun yarn process, wherein the pre-drafting multiple of the spandex filament is 4 times.

Preparation example 2

The preparation method of the cement modified soil comprises the following steps:

the method comprises the steps of obtaining soil materials from a soil sampling field, and crushing the soil materials by using a hydraulic soil crusher to enable the particle size of the soil materials to be less than or equal to 10cm, wherein the content of the soil materials with the particle size of 5-10 cm is 5%, and the content of the soil materials with the particle size of 0.5-5 cm is 50%.

Adding 91.5 tons of soil materials after soil crushing, 8 tons of cement and 0.5 ton of composite fiber prepared in preparation example 1 into a mixing station, firstly performing dry mixing, uniformly mixing, then adding water, and performing wet mixing until the mixture is uniformly mixed to obtain the cement modified soil, wherein the water content of the cement modified soil is 16%.

Preparation example 3

The difference between the preparation example and the preparation example 2 is that: the dosage of the soil material is 92.6 tons, the dosage of the cement is 7 tons, the dosage of the composite fiber is 0.4 ton, and the water content of the cement modified soil is 17 percent.

Preparation example 4

The difference between the preparation example and the preparation example 2 is that: the dosage of the soil material is 93.8 tons, the dosage of the cement is 6 tons, the dosage of the composite fiber is 0.2 tons, and the water content of the cement modified soil is 18 percent.

Preparation example 5

The difference between this preparation and preparation 3 is that: in this preparation, no conjugate fiber was present.

Performance test

Test method

The cement modified soil prepared in preparation examples 2 to 5 was respectively prepared into cubic test molds according to the method of "stirring, molding and curing of a.2 test piece" in JGJ/T233-2011, the size was 70.7mm, curing was performed for 7 days, and then an unconfined compressive strength test was performed on each test mold according to the method of "appendix b.2 unconfined compressive strength test" in JGJ/T233-2011, the rate was 0.1kN/s, and the test results are detailed in table 1.

TABLE 1

Test results	Preparation example 2	Preparation example 3	Preparation example 4	Preparation example 5
					Unconfined compressive strength/MPa	1.54	1.62	1.57	1.03

It can be seen from the combination of preparation examples 3 and 5 and table 1 that the cement modified soil prepared in preparation example 3 has better elasticity and tensile strength than the cement modified soil prepared in preparation example 5 due to the addition of more composite fibers, the composite fibers are formed by spinning spandex filaments as cores and wrapping chopped glass fibers, and the composite fibers, soil materials, cement and water are mixed to prepare the cement modified soil. From the test results, the unconfined compressive strength of the cement modified soil prepared in preparation example 3 is 1.57 times that of the cement modified soil prepared in preparation example 5, and the effect of improving the strength of the cement modified soil by adding the composite fiber is reflected, so that the effect of improving the filling quality of the roadbed is obtained.

Examples

Example 1

A cement modified soil roadbed filling process comprises the following steps:

s1, site cleaning and leveling: transplanting and cleaning trees, shrubs and the like in the field range, digging all roots in the field range, filling and tamping pits, and leveling the field by using a grader. The site is averagely divided into a plurality of filling areas, and the following filling processes are respectively carried out.

S2, filling a protective layer, wherein the protective layer can be used for solidifying sulfate ions.

The protective layer comprises a filler, the filler comprises river sand and broken stones with a mass ratio of 6:4, the strength supporting effect of the bottom of the roadbed can be achieved, and the migration of sulfate ions can be reduced by staggered filling formed by different particle sizes of the river sand and the broken stones.

The river sand and the broken stones are evenly mixed and then spread on the ground, the ground is divided into two layers, and the solidified cloth is laid between the fillers spread on the two layers, wherein the solidified cloth is the geotextile impregnated with the calcium chloride. When rainwater permeates into the protective layer, calcium chloride on the geotextile is dissolved to generate calcium ions, the calcium ions are combined with sulfate ions leached by the rainwater to generate calcium sulfate, and calcium sulfate precipitates are adsorbed on the filler, so that the sulfate ions are solidified, gaps among the fillers are filled, and the strength of the protective layer is enhanced. The migration condition of sulfate ions is reduced, so that the damage condition of the sulfate ions to the cement modified soil is reduced, and the filling quality of the roadbed is improved.

Each solidification cloth sets up along the length direction of ground, and end to end connection sets up in the filler to make more sulfate radical ions and solidification cloth contact and be solidified, reduce the condition that sulfate radical ion migrated the protective layer to a great extent, further improve the solidification effect to sulfate radical ion.

And rolling the protective layer, wherein the protective layer is subjected to static pressure once, weak vibration once and strong vibration three times during rolling, and the compaction thickness is kept within the range of 10-12 cm.

And laying a reverse osmosis membrane after the protective layer is rolled so as to further reduce the condition that sulfate ions migrate out of the protective layer.

S3, conveying the cement modified soil prepared in the preparation example 2 to a filling area, paving the cement modified soil on a reverse osmosis membrane, using a bulldozer to step on the paved cement modified soil flatly, and leveling the soil by using a grader until the loose pavement thickness is 25 +/-1 cm.

And S4, rolling the cement modified soil by a road roller by adopting a forward-backward staggered distance method, carrying out static pressure for 2 times, then carrying out vibration rolling for 6 times, wherein the rolling speed is 3km/h, the compaction thickness is 18 +/-1 cm, and sprinkling water or airing at any time in the rolling process to control the water content to be 12.3% so as to obtain the cement modified soil layer.

In the above S2-S4, the joints of the protective layers between the filling areas are filled and rolled by a lapping method, that is, the former filling area is left by 5% of the area of the filling area, and the former filling area and the next filling area are constructed together to keep the joints between the filling areas connected tightly. And in the construction process, the quality of each filling area is detected and adjusted at any time so as to control the construction quality.

And S5, maintaining for 7 days by adopting a covering method, and covering soil with the thickness of 5cm to obtain the roadbed.

Example 2

This example differs from example 1 in that: the cement-modified soil prepared in preparation example 3 was used, the loose paving thickness of the cement-modified soil was 30. + -.1 cm, the compacted thickness was 23. + -.1 cm, the water content rate during rolling was controlled to be 13.8%, and the curing days were 9 days.

Example 3

This example differs from example 1 in that: the cement-modified soil prepared in preparation example 4 was used, the loose paving thickness of the cement-modified soil was 35. + -.1 cm, the compacted thickness was 28. + -.1 cm, the water content rate during rolling was controlled to 15.6%, and the curing days were 11 days.

Example 4

This example differs from example 2 in that: the cement-modified soil prepared in preparation example 5 was used.

The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.