CN101423353B - Method for improving expansive soil by waste foundry sand and construction method - Google Patents
Method for improving expansive soil by waste foundry sand and construction method Download PDFInfo
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- CN101423353B CN101423353B CN2008102439107A CN200810243910A CN101423353B CN 101423353 B CN101423353 B CN 101423353B CN 2008102439107 A CN2008102439107 A CN 2008102439107A CN 200810243910 A CN200810243910 A CN 200810243910A CN 101423353 B CN101423353 B CN 101423353B
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Abstract
The invention discloses a method for modifying expansive soil by waste foundry sand, which comprises the following steps: step one, according to the proportion of between 1 to 5 and 1 to 3 of the mass of the waste foundry sand to the mass of dry soil of a soil body needing to be improved, weighing the waste foundry sand and the soil body to be improved, and mixing the waste foundry sand and the soil body evenly, wherein the components of the waste foundry sand in mass percentage are: 41 percent of quartz sand, 37 percent of coal dust, 19 percent of clay and 3 percent of iron; step two, determining the optimum moisture content; and step three, adding water to the mixed soil obtained in the step one, and stirring the mixture evenly to obtain waste foundry sand improved expansive soil. The method for using the waste foundry sand to improve the expansive soil is utilized to obtain a construction method for using the waste foundry sand to improve the expansive soil. With a method for constructing the waste foundry sand improved expansive soil which is obtained by the method for improving the expansive soil by the waste foundry sand, the obtained waste foundry sand improved expansive soil is paved as a surface improved layer the thickness of which is between 30 and 60 centimeters on the construction surface; and then the surface improved layer is kept for 3 to 7 days under natural condition, and the improved soil body has a chemical reaction with the components of the waste foundry sand to eliminate or reduce the swell-shrink characteristics of the soil body in the improved layer, thus the strength required by an engineering can be achieved.
Description
Technical field
What the present invention relates to is a kind of expansive soil improvement method, is specifically related to choosing and improving swelling soil intensity and reduce the method for dilatational strain the optimum mix amount of a kind of discarded casting sand.Belong to geologic hazard processing and geotechnical engineering technical field.
Background technology
Up to the present, the expansive soil improvement method mainly contains: compacting method, physically improved method, chemical amendments, the method for preserving moisture, soil replacement method and biological modification method.
(1) compacting method is that swelling soil is compacted to desired density.Compacting method expense is low, but certain limited applicability is arranged, and it generally is applicable to weak expansive soil foundation, and the expansive soil foundation dry density after the compacting can increase, and cohesive force and internal friction angle also increase, and bearing capacity of foundation soil improves.
(2) physically improved method comprises the soil nailing wall, and pile foundation adds geotextile and mix the methods such as grating that sandy gravel changes soil in swelling soil.Physically modified method construction is simple, but execution conditions, restricted application.
(3) chemical modifying method is that Xiang Tuzhong mixes inorganic salts or organic substance etc., improves interaction between the water and soil by the surface reaction of catalytic activation grogs, makes the character of soil still can reach set index under the influence of water, improves the engineering properties of swelling soil.
(4) method of preserving moisture is that the variation of water ratio is the most direct factor that causes the swelling soil expand with wet and contract with dry, and the method for preserving moisture is exactly to keep the water ratio in the soil constant.
(5) soil replacement method is a kind of swelling soil under the ground is cut out and change the method for common great soil group or dirt into, and this method can thoroughly be effected a radical cure the harm that swelling soil causes.
(6) the biological modification method is exactly to utilize bio-surfactant attached to reducing liquid level tension force on the surface of clay mineral and making clay mineral surface-hydrophobicized, destroy the mineral surface hydration shell or make it attenuation, thereby make interparticle bonding power become big, the slip resistance of soil improves, and swell-shrink characteristic reduces.
(7) existing physically improvedly have chemical modifying method to be meant again to mix lime, cement, flyash, slag and compound thereof by a certain percentage in swelling soil, adds the stable reaction soil that a certain amount of active catalyst promotes modifying agent and soil.
The transformation of summing up above 7 kinds of method swelling soils mainly contains modification and structural transformation two big classes, wherein, comparative maturity and method commonly used are lime, flyash improvement in the method for modifying, these two kinds of methods all are to utilize the hydrate and the mutual cementation of soil particle of silicate and aluminium, along with cementing matter dewaters and neogenic crystallization gradually, form gelling become to assign to binder soil earth, stop up the capillary structure of soil, thereby reduce liquid limit, increase the slip resistance of the soil body.This is present comparatively successful soil-solidified-agent, but the speed of response of lime and cement and soil is slower, and the hydrate intensity that is generated is lower, and weather resistance is relatively poor, and lime intermingled quantity is more than 8%, cement mixing content just can reach certain effect more than 6%, and construction volume is very high, needs uniform mixing repeatedly during construction, cycle is long, consume man-hour, and be difficult for holding, occur hidden danger of quality easily.Simultaneously also there is contaminate environment in it, is unfavorable for problem such as greening.For seek economy, effectively, the swelling soil filler improvement new way of environmental protection, Chinese scholars has proposed the heavy addition agent method from different approach, wherein macromolecular material has become focus as additive.But, but the test effect of at present domestic interpolation scheme is unsatisfactory and generalization is relatively poor.
And the sand of casting usefulness mostly is high grade quartz sand and (contains SiO
2More than the 85%-95%), the more expensive non-quartz sand of price that still can stand higher temperature (1600 ℃) that has.China's high grade quartz sand resource relative shortage if cast used sand is not fully utilized and a large amount of discarding, is great waste to limited resources, and can cause serious environmental to pollute.
Summary of the invention
Purpose of the present invention just is to overcome above-mentioned defective, the invention provides a kind of method of improving expansive soil by waste foundry sand and with the constructional method of the improving expansive soil by waste foundry sand that obtains, can effectively solve the swelling soil swell-shrinking deformation and destroy problem and improve swelling soil intensity, be easy to promote.
Technical solution of the present invention is a kind of method of improving expansive soil by waste foundry sand, and step is:
The first step, in discarded casting sand quality: the ratio of the dry ground quality of the required improvement soil body=1: 5～1: 3, take by weighing the discarded casting sand and the improvement soil body, mix; Consisting of of described discarded casting sand is in the mass percent ratio: quartz sand 41%, coal dust 37%, potter's clay 19%, iron 3%.Described quartz sand contains SiO
285%-95%wt.
Second the step, by " highway earthwork test rule " (JTJ-051-93) medium and heavy compaction test determine optimum moisture content;
The 3rd step added water in the composite soil that the first step obtains by the water yield of the optimum moisture content of determining, can adopt the mix of successively sprinkling water, and water is dispersed in the mixture, and stirring obtains improving expansive soil by waste foundry sand.
Using the constructional method of the improving expansive soil by waste foundry sand that the method for described improving expansive soil by waste foundry sand obtains, is the surfaction layer of 30～60cm at the construction surface laying depth with the improving expansive soil by waste foundry sand that obtains; Then, kept under field conditions (factors) 3～7 days, the composition generation chemical reaction in the improvement soil body and the discarded casting sand, the swell-shrink characteristic of the soil body can reach requirement of engineering intensity in elimination or the reduction improvement layer.
Beneficial effect:
At first, the present invention directly uses depleted casting sand improvement swelling soil, has both saved engineering cost, and discarded casting sand is reused, and has protected environment, and the engineering project disaster that causes for the minimizing swelling soil has been opened up a new modification method again.
Secondly, the discarded contained casting sand of casting adds as coarse aggregate, and casting sand plays skeleton function, but also can improve the mixture grating, and discarded casting sand uniform distribution in swelling soil has good physicals, belongs to physically improved method;
Once more, the iron that discarded casting sand includes reacts after adding water, can generate iron rust, the force of cohesion of mixture is strengthened, further improve swelling soil, effectively improve swelling soil intensity, belong to chemical modifying, the present invention effectively combines physically improved and advantage chemical modifying method.
Embodiment
Depleted casting sand behind the cast iron that discarded casting sand material provides for Taining, Nanjing cast iron company limited
A kind of method of improving expansive soil by waste foundry sand, step is:
The first step, in discarded casting sand quality: the ratio of the dry ground quality of the required improvement soil body=1: 5～1: 3, take by weighing the discarded casting sand and the improvement soil body, mix; Consisting of of described discarded casting sand is in the mass percent ratio: quartz sand 41%, coal dust 37%, potter's clay 19%, iron 3%.Described quartz sand contains SiO
285%-95%wt.
Second the step, by " highway earthwork test rule " (JTJ-051-93) medium and heavy compaction test determine optimum moisture content;
The 3rd step added water in the composite soil that the first step obtains by the water yield of the optimum moisture content of determining, can adopt the mix of successively sprinkling water, and water is dispersed in the mixture, and stirring obtains improving expansive soil by waste foundry sand.
Using the constructional method of the improving expansive soil by waste foundry sand that the method for described improving expansive soil by waste foundry sand obtains, is the surfaction layer of 30～60cm at the construction surface laying depth with the improving expansive soil by waste foundry sand that obtains; Then, kept under field conditions (factors) 3～7 days, the composition generation chemical reaction in the improvement soil body and the discarded casting sand, the swell-shrink characteristic of the soil body can reach requirement of engineering intensity in elimination or the reduction improvement layer.
Embodiment 1
The mixture preparation is with preparation 1kg mixture.The processing step of mixture preparation is as follows: (1) needs the dry ground quality of the improvement soil body is 0.8kg, (the cast waste sand quality: dry ground quality=1: 4) take by weighing after required cast waste sand quality 0.2kg (2) mixes that is 25% by mass percentage, the optimum moisture content 15.1%wt that (JTJ-051-93) obtains in the medium and heavy compaction test by " highway earthwork test rule ", 151g water is joined in this mixture, and the layering blunge prevents to form pimple.
The improvement construction method step is: the cast waste sand-improvement dry ground mixture for preparing is laid the surfaction layer that forms the required thickness 40cm of engineering.
Improved effect: (1) swell-shrink characteristic: (JTJ-051-93) do the expansion overall rate according to " highway earthwork test rule " and test, pure swelling soil expansion overall rate is 2.801%, when mixing discarded casting sand rate when reaching 20%wt, the mixture expansion overall rate only is 0.130%, the requirement of expansion overall rate eps≤0.7% of the improvement swelling soil of satisfied " highway subgrade construction technique normalizing " defined; (2) intensity: according to " highway earthwork test rule " (JTJ-051-93) unconfined compressive strenght test of doing, when pure swelling soil water ratio is 14.2%, its intensity reaches peak value, is 704.45kpa, but its intensity is violent with the water ratio variable effect, cause construction quality impaired so be easy to generate the breathing variation, and mix discarded casting sand rate when reaching 20%wt, its mixture intensity peak is 731.15kpa, has not only improved intensity, and intensity is less with the water ratio influence, is applicable to the engineering application.
Embodiment 2
A kind of method of improving expansive soil by waste foundry sand, step is:
The first step, in discarded casting sand quality: the ratio of the dry ground quality of the required improvement soil body=1: 5, take by weighing the discarded casting sand and the improvement soil body, mix; Consisting of of described discarded casting sand is in the mass percent ratio: quartz sand 41%, coal dust 37%, potter's clay 19%, iron 3%.Described quartz sand contains SiO
285%wt.
Second the step, by " highway earthwork test rule " (JTJ-051-93) medium and heavy compaction test determine optimum moisture content;
The 3rd step added water in the composite soil that the first step obtains by the water yield of the optimum moisture content of determining, can adopt the mix of successively sprinkling water, and water is dispersed in the mixture, and stirring obtains improving expansive soil by waste foundry sand.
Using the constructional method of the improving expansive soil by waste foundry sand that the method for described improving expansive soil by waste foundry sand obtains, is the surfaction layer of 30cm at the construction surface laying depth with the improving expansive soil by waste foundry sand that obtains; Then, kept under field conditions (factors) 3 days, the composition generation chemical reaction in the improvement soil body and the discarded casting sand, the swell-shrink characteristic of the soil body can reach requirement of engineering intensity in elimination or the reduction improvement layer.
Embodiment 3
A kind of method of improving expansive soil by waste foundry sand, step is:
The first step, in discarded casting sand quality: the ratio of the dry ground quality of the required improvement soil body=1: 3, take by weighing the discarded casting sand and the improvement soil body, mix; Consisting of of described discarded casting sand is in the mass percent ratio: quartz sand 41%, coal dust 37%, potter's clay 19%, iron 3%.Described quartz sand contains SiO
285%-95%wt.
Second the step, by " highway earthwork test rule " (JTJ-051-93) medium and heavy compaction test determine optimum moisture content;
The 3rd step added water in the composite soil that the first step obtains by the water yield of the optimum moisture content of determining, can adopt the mix of successively sprinkling water, and water is dispersed in the mixture, and stirring obtains improving expansive soil by waste foundry sand.
Using the constructional method of the improving expansive soil by waste foundry sand that the method for described improving expansive soil by waste foundry sand obtains, is the surfaction layer of 60cm at the construction surface laying depth with the improving expansive soil by waste foundry sand that obtains; Then, kept under field conditions (factors) 7 days, the composition generation chemical reaction in the improvement soil body and the discarded casting sand, the swell-shrink characteristic of the soil body can reach requirement of engineering intensity in elimination or the reduction improvement layer.
Claims (3)
1. the method for an improving expansive soil by waste foundry sand is characterized in that, step is:
The first step, in discarded casting sand quality: the ratio of the dry ground quality of the required improvement soil body=1: 5～1: 3, take by weighing the discarded casting sand and the improvement soil body, mix;
Second the step, by " highway earthwork test rule " (JTJ-051-93) medium and heavy compaction test determine optimum moisture content;
The 3rd step added water in the composite soil that the first step obtains by the water yield of the optimum moisture content of determining, stirring obtains improving expansive soil by waste foundry sand;
Consisting of of described discarded casting sand, by percentage to the quality: quartz sand 41%, coal dust 37%, potter's clay 19%, iron 3%.
2. the method for improving expansive soil by waste foundry sand as claimed in claim 1 is characterized in that, described quartz sand contains SiO
285%-95%wt.
3. using the constructional method of the improving expansive soil by waste foundry sand that the method for improving expansive soil by waste foundry sand as claimed in claim 1 obtains, it is characterized in that, is the surfaction layer of 30～60cm at the construction surface laying depth with the improving expansive soil by waste foundry sand that obtains; Then, kept under field conditions (factors) 3～7 days, can reach requirement of engineering intensity.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2008102439107A CN101423353B (en) | 2008-12-10 | 2008-12-10 | Method for improving expansive soil by waste foundry sand and construction method |
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| CN2008102439107A CN101423353B (en) | 2008-12-10 | 2008-12-10 | Method for improving expansive soil by waste foundry sand and construction method |
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| CN101423353B true CN101423353B (en) | 2010-12-08 |
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Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101805159B (en) * | 2010-04-14 | 2012-05-30 | 苏益仁 | Liquid-state casting fast curing-formed high-temperature resistant pottery clay and moulding technology |
| CN102352622B (en) * | 2011-07-25 | 2013-12-11 | 河海大学 | Method for improving swelling soil by using alkali residue and construction method for alkali- residue-modified soil |
| CN103184733A (en) * | 2011-12-27 | 2013-07-03 | 河海大学 | Method for improving expansive soil and construction method thereof |
| CN105887801A (en) * | 2016-05-16 | 2016-08-24 | 浙江工业大学 | Method for improving expansive soil foundation through ardealite and waste tire rubber powder |
| CN108385662A (en) * | 2018-01-29 | 2018-08-10 | 河海大学 | A method of utilizing silicon ash stabilized expansive soil property |
| CN109536175B (en) * | 2018-12-05 | 2021-03-23 | 内蒙古农业大学 | Expansive soil modifier, preparation and application thereof and method for modifying expansive soil by using expansive soil modifier |
| CN112458816A (en) * | 2020-11-21 | 2021-03-09 | 蓝海建设集团有限公司 | Weak expansion soil roadbed construction process |
| CN113308250A (en) * | 2021-06-23 | 2021-08-27 | 合肥工业大学 | Utilization method of waste stone |
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