CN114775350A - Comprehensive treatment method for low liquid limit silt subgrade - Google Patents
Comprehensive treatment method for low liquid limit silt subgrade Download PDFInfo
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- CN114775350A CN114775350A CN202210294791.8A CN202210294791A CN114775350A CN 114775350 A CN114775350 A CN 114775350A CN 202210294791 A CN202210294791 A CN 202210294791A CN 114775350 A CN114775350 A CN 114775350A
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C3/00—Foundations for pavings
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C3/00—Foundations for pavings
- E01C3/04—Foundations produced by soil stabilisation
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C3/00—Foundations for pavings
- E01C3/06—Methods or arrangements for protecting foundations from destructive influences of moisture, frost or vibration
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- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Pit Excavations, Shoring, Fill Or Stabilisation Of Slopes (AREA)
Abstract
The invention discloses a comprehensive treatment method for a low liquid limit silt subgrade, which is implemented according to the following steps: step 1, replacing a pebble filling layer; step 2, arranging a geotextile impermeable layer on the pebble layer in the step 1; step 3, arranging a silty soil embankment on the geotextile impervious layer in the step 2, and arranging a pebble slope toe and a cement soil layer at the toe of the silty soil embankment, wherein the silty soil embankment is covered by geotextile; step 4, arranging a cement soil area on the silty soil embankment in the step 3; and 5, arranging a road surface and a road shoulder on the cement soil area obtained in the step 4. The comprehensive treatment method for the low liquid limit silt subgrade solves the foundation treatment problem of the liquid limit silt.
Description
Technical Field
The invention belongs to the technical field of roadbed construction, and particularly relates to a comprehensive treatment method for a low liquid limit silt roadbed.
Background
The silt is more than half of the total mass of the silt with the particle size not more than 0.075mm, and the plasticity index of the silt is not more than 10. Generally, dense silt can be used as a good material of a foundation, but the liquid limit and plasticity index of low liquid limit silt are lower, and the mechanical property and water stability are poorer, so that the saturated low liquid limit silt is easy to be vibrated and liquefied during an earthquake, the pore water pressure in a soil body is increased suddenly, the stress among soil particles is reduced to zero, the shear strength is reduced, the bearing capacity of the foundation is lost, and a ground building is damaged. When planning a route, filling and digging balance during construction is ensured as much as possible, the aim is to effectively utilize the excavated earthwork during road construction, reduce earthwork waste to reduce cost, and have certain requirements on roadbed construction when the earthwork is low liquid limit silt while local materials are used. In order to reinforce the roadbed, mechanical methods such as rolling compaction or dynamic compaction can be adopted to reduce the porosity of the soil body and improve the compactness, but the compaction of low liquid limit silt is difficult and water seepage is easy when rainfall occurs, so that the single mechanical treatment effect is not ideal. Or the roadbed material is changed into the stone soil and the sandy soil with better engineering property by filling, so that the replacement materials are transported to take time and financial resources in the aspect of soil excavation and filling, and the waste parties also occupy land resources in the aspect of treatment. The foundation treatment aiming at the low liquid limit silt is a big problem in the current road construction, and the poor performance of the low liquid limit silt cannot be used in the high-standard roadbed construction, so that the application of the low liquid limit silt in the roadbed construction is restricted, the construction cost is invisibly increased, and the construction progress is influenced.
Disclosure of Invention
The invention aims to provide a comprehensive treatment method for a low liquid limit silt subgrade, which solves the problem of foundation treatment of liquid limit silt.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows: a comprehensive treatment method for a low liquid limit silt subgrade is implemented according to the following steps:
step 4, arranging a cement soil area on the silty soil embankment in the step 3;
and 5, arranging a road surface and a road shoulder on the cement soil area obtained in the step 4.
In a preferred embodiment of the present invention, in step 1, the pebble layer is 1.8m to 2 m.
As a preferable technical solution of the present invention, in the step 3, if the height of the silty soil embankment is greater than 4m, a filler or a soil cement cover layer is arranged every 3m to 4 m.
In a preferred embodiment of the present invention, in the step 3, the thickness of the filler or the soil cement coating layer is 0.25 m.
In a preferred embodiment of the present invention, in the step 3, the cement soil layer includes a thickness of 0.50m, which is 1.5m beyond and 1.5m inward of the toe of the silty soil embankment.
In a preferred embodiment of the present invention, in step 3, the depth h of the cement layer is determined by the thickness of the bearing stratum or 2 meters below the potential sliding surface, and the width L is determined by half the filling height of the roadbed.
The invention has the beneficial effects that: (1) according to the comprehensive treatment method for the low liquid limit silt subgrade, silt obtained by replacing and filling pebbles at the base of the embankment is used for embankment filling, road excavation is fully utilized, earthwork abandonment is reduced, construction cost is reduced, and earthwork allocation is optimized, so that engineering development is facilitated. (2) According to the comprehensive treatment method for the low liquid limit silt subgrade, the subgrade settlement is reduced by filling pebbles at the base of the embankment, the stability is improved by adding the pebbles at the toe of the slope, and the pebbles are used for dissipating the pore water pressure of the base. The range of the slope toe added with pebbles is determined by the thickness of the bearing layer or the potential sliding surface and the filling height, so that the influence of the weak part of the base and the self weight of the filled soil of the embankment on the stability of the roadbed is controlled. (3) According to the comprehensive treatment method for the silt subgrade with the low liquid limit, the cement soil layer is laid on the slope toe to prevent seepage and scouring from taking away silt particles, so that the bearing capacity of the subgrade is invalid, the geotextile impervious layer is arranged on the base of the embankment, the geotextile is laid on the first layer of silt on the cement soil layer in the same way and is reversely wrapped twice, and the effect of water is reduced by reverse filtration. The method is used for taking measures for the poor water stability of the silt subgrade and preventing the influence caused by particle erosion on multiple road positions. (4) According to the comprehensive treatment method for the silt subgrade with the low liquid limit, provided by the invention, a vibration compaction process can be adopted, the construction progress can be accelerated on the premise of ensuring the compaction effect, the influence on the quality of the subgrade entity and the construction progress caused by mechanical equipment and a construction method is reduced as much as possible, the subgrade strength is improved and the water permeability is reduced due to the vibration compaction of silt. (5) According to the comprehensive treatment method for the low liquid limit silt subgrade, the filler or the cement soil covering layer is arranged for multiple times in the embankment filling process, so that the stress on the upper layer is uniformly diffused into the low liquid limit silt subgrade, the subgrade is prevented from being damaged due to stress concentration, and the bearing capacity and the stability of the subgrade are improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a construction schematic diagram of the comprehensive treatment method for the low liquid limit silt subgrade.
In the figure: 1. a pebble layer; 2. a geotextile impervious layer; 3. a pebble toe; 4. a cement soil layer; 5. a silty soil embankment; 6. a geotextile covering layer; 7. a filler or soil cement overlay; 8. a cement soil area; 9. road surface and curb.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention and are not to be construed as limiting the present invention.
In the description of the present invention, unless otherwise specifically limited, terms such as set, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention by combining the specific contents of the technical solutions.
The application provides a method for treating a low liquid limit silt subgrade, which can optimize an original subgrade design scheme, fully utilize silt soil of a road range excavation and an original design borrowing field, reduce waste earthwork and accelerate engineering progress.
Referring to fig. 1, a shallow soft low-liquid limit silt embankment base with a thickness within 3m can be processed by a replacement filling method, the replacement depth is based on the principle that the bearing capacity of the base is met, a vibratory roller compaction method or a gravity dynamic compaction method can be adopted for compaction, the compaction degree meets the requirement of embankment base processing, a pebble layer is replaced by 1.8-2 m in the embodiment, and a geotextile layer is laid above the pebble layer to prevent embankment silt particles from being washed away and lost. The pebble slope toe is additionally arranged at the slope toe of the roadbed, the depth h of the pebble slope toe is determined according to the thickness of a bearing layer (namely the thickness of a soil layer directly bearing a foundation load) or 2 meters below a potential sliding surface (the depth of the bottom of an arc interface where soil body landslide occurs is added with 2 meters), the width L of the pebble slope toe is determined according to half of the filling height of the roadbed (namely the width L is half of the sum of the heights of a powdery soil embankment, a cement soil area, a road surface and a road shoulder in the attached drawing 1), and by additionally arranging the pebble slope toe, the slip of the powdery soil filling side slope can be prevented, and the pore water pressure of a substrate is dissipated. The foundation is changed with filling particles, the foundation is preferably covered and protected by cement soil, the cement soil is covered and filled with the particles, the cement soil treatment range comprises that the cement soil treatment range exceeds 1.5m outside a slope toe of the filled soil of the embankment and extends 1.5m inside the slope toe, the thickness is 0.50m, the cement soil treatment range is preferably compacted by a vibratory roller, and the compaction degree is not lower than 96% of the heavy standard. When the first layer is filled with the low liquid limit silt on the cement soil, the whole filling layer is wrapped by geotextile to prevent contact scouring. When the silty soil embankment is filled, a filler or cement soil covering layer with the thickness of 0.25m is paved every 3-4 m when the filling height is more than 4m, and the paving aims to uniformly diffuse the load above the filling layer to the low liquid limit silty soil roadbed. In the compaction control of embankment filling, construction processes of dump truck transportation, bulldozer paving and grader leveling are adopted, the axle weight of a dump truck needs to be controlled in construction, and when axle weight control is difficult, the wheel tracks of vehicles need to be compacted by a road roller before soil unloading. And adopting a double-steel-wheel vibratory roller to perform vibratory compaction, wherein the vibration frequency is 40-67 Hz, and the required compactness can be achieved by rolling for 3-4 times. When the steel wheel vibratory roller is driven by a tire to perform compaction, the vibration frequency is not lower than 28Hz, the low-amplitude small vibration rolling is adopted, the rolling times are 5-6 times, and the wheel track is smoothed in a retreating vibration or static pressure mode in the last rolling step. The roadbed and the upper embankment are paved with cement soil within the range of 1.5m, and the last layer of pavement of the lower embankment below the roadbed and the upper embankment are also wrapped with geotextile to prevent contact scouring. And finally, carrying out pavement and shoulder construction.
Thus, compared to the prior art: according to the comprehensive treatment method for the low liquid limit silt subgrade, silt obtained by replacing and filling pebbles at the base of the embankment is used for embankment filling, road excavation is fully utilized, earthwork abandonment is reduced, construction cost is reduced, and earthwork allocation is optimized, so that engineering development is facilitated. (2) According to the comprehensive treatment method for the low liquid limit silt subgrade, the subgrade settlement is reduced by filling pebbles at the base of the embankment, the stability is improved by adding the pebbles at the toe of the slope, and the pebbles are used for dissipating the pore water pressure of the base. The range of the slope toe added with pebbles is determined by the thickness of the bearing layer or the potential sliding surface and the filling height, so that the influence of the weak part of the base and the self weight of the filled soil of the embankment on the stability of the roadbed is controlled. (3) According to the comprehensive treatment method for the silt subgrade with the low liquid limit, the cement soil layer is laid on the slope toe to prevent seepage and scouring from taking away silt particles, so that the bearing capacity of the subgrade is invalid, the geotextile impervious layer is arranged on the base of the embankment, the geotextile is laid on the first layer of silt on the cement soil layer in the same way and is reversely wrapped twice, and the effect of water is reduced by reverse filtration. The method aims at the problems that the silty soil subgrade has poor water stability, measures are taken for multiple places of the subgrade, and the influence caused by particle erosion is prevented. (4) According to the comprehensive treatment method for the silt subgrade with the low liquid limit, provided by the invention, a vibration compaction process can be adopted, the construction progress can be accelerated on the premise of ensuring the compaction effect, the influence on the quality of the subgrade entity and the construction progress caused by mechanical equipment and a construction method is reduced as much as possible, the subgrade strength is improved and the water permeability is reduced due to the vibration compaction of silt. (5) According to the comprehensive treatment method for the low liquid limit silt subgrade, the filler or the cement soil covering layer is arranged for multiple times in the filling of the embankment, so that the stress on the upper layer is ensured to be uniformly diffused into the low liquid limit silt subgrade, the subgrade is prevented from being damaged due to stress concentration, and the bearing capacity and the stability of the subgrade are improved.
While the foregoing description shows and describes several preferred embodiments of the invention, it is to be understood, as noted above, that the invention is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (6)
1. A comprehensive treatment method for a low liquid limit silt subgrade is characterized by comprising the following steps:
step 1, replacing a pebble filling layer;
step 2, arranging a geotextile impervious layer on the pebble layer in the step 1;
step 3, arranging a silty soil embankment on the geotextile impervious layer in the step 2, and arranging a pebble slope toe and a cement soil layer at the toe of the silty soil embankment, wherein the silty soil embankment is covered by geotextile;
step 4, arranging a cement soil area on the silty soil embankment in the step 3;
and 5, arranging a road surface and a road shoulder on the cement soil area obtained in the step 4.
2. The comprehensive treatment method for the silt-bearing subgrade with the low liquid limit of claim 1, wherein in the step 1, the pebble layer is 1.8-2 m.
3. The comprehensive treatment method for the silt-low subgrade in claim 2, characterized in that in the step 3, if the height of the silt embankment is more than 4m, a filler or a cement soil covering layer is arranged every 3m-4 m.
4. The comprehensive treatment method for the low liquid limit silt subgrade according to the claim 3, characterized in that in the step 3, the thickness of the filler or the soil cement cover layer is 0.25 m.
5. The comprehensive treatment method for the silt subgrade with the low liquid limit according to the claim 4, characterized in that in the step 3, the cement soil layer comprises 1.5m beyond the toe of the silt embankment and 1.5m extending inward the toe, and the thickness is 0.50 m.
6. The comprehensive treatment method for the silt subgrade with the low liquid limit of claim 5, characterized in that in the step 3, the depth h of the cement soil layer is determined according to the thickness of a bearing stratum or 2 meters below a potential sliding surface, and the width L is determined according to half of the filling height of the subgrade.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210294791.8A CN114775350A (en) | 2022-03-23 | 2022-03-23 | Comprehensive treatment method for low liquid limit silt subgrade |
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| CN202210294791.8A CN114775350A (en) | 2022-03-23 | 2022-03-23 | Comprehensive treatment method for low liquid limit silt subgrade |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115354542A (en) * | 2022-09-05 | 2022-11-18 | 山东省公路桥梁建设集团有限公司 | Treatment method for road submerged roadbed, soil solidification material and preparation method |
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| JP2002121720A (en) * | 2000-10-12 | 2002-04-26 | Kanto Regional Development Bureau Ministry Of Land Infrastructure & Transport | Levee drain structure and its construction method |
| CN201485765U (en) * | 2009-08-25 | 2010-05-26 | 科达集团股份有限公司 | Novel low liquid limit silty soil subgrade |
| CN106283944A (en) * | 2016-08-09 | 2017-01-04 | 中电建路桥集团有限公司 | Method for reinforcing shallow soft foundation by pressing and filling rubbles and/or blocks |
| CN208136652U (en) * | 2018-04-12 | 2018-11-23 | 浙江大学城市学院 | Shallow-layer solidifies Piled Embankments |
| CN112160208A (en) * | 2020-08-13 | 2021-01-01 | 北京市政路桥股份有限公司 | Filling roadbed construction method suitable for water-rich low-lying permafrost region |
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2022
- 2022-03-23 CN CN202210294791.8A patent/CN114775350A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002121720A (en) * | 2000-10-12 | 2002-04-26 | Kanto Regional Development Bureau Ministry Of Land Infrastructure & Transport | Levee drain structure and its construction method |
| CN201485765U (en) * | 2009-08-25 | 2010-05-26 | 科达集团股份有限公司 | Novel low liquid limit silty soil subgrade |
| CN106283944A (en) * | 2016-08-09 | 2017-01-04 | 中电建路桥集团有限公司 | Method for reinforcing shallow soft foundation by pressing and filling rubbles and/or blocks |
| CN208136652U (en) * | 2018-04-12 | 2018-11-23 | 浙江大学城市学院 | Shallow-layer solidifies Piled Embankments |
| CN112160208A (en) * | 2020-08-13 | 2021-01-01 | 北京市政路桥股份有限公司 | Filling roadbed construction method suitable for water-rich low-lying permafrost region |
Non-Patent Citations (1)
| Title |
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| 李上红等, 北京：人民交通出版社 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115354542A (en) * | 2022-09-05 | 2022-11-18 | 山东省公路桥梁建设集团有限公司 | Treatment method for road submerged roadbed, soil solidification material and preparation method |
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