CN112726684A - Method for inhibiting frost heaving deformation of fiber-modified stratum - Google Patents
Method for inhibiting frost heaving deformation of fiber-modified stratum Download PDFInfo
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- CN112726684A CN112726684A CN202011559357.5A CN202011559357A CN112726684A CN 112726684 A CN112726684 A CN 112726684A CN 202011559357 A CN202011559357 A CN 202011559357A CN 112726684 A CN112726684 A CN 112726684A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D31/00—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution
- E02D31/10—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure
- E02D31/14—Protective arrangements for foundations or foundation structures; Ground foundation measures for protecting the soil or the subsoil water, e.g. preventing or counteracting oil pollution against soil pressure or hydraulic pressure against frost heaves in soil
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- Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
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- Excavating Of Shafts Or Tunnels (AREA)
Abstract
The invention discloses a method for inhibiting frost heaving deformation of a fiber-improved stratum, which is suitable for urban underground freezing construction. The fiber modified stratum is constructed in the quasi-freezing area, in order to prevent the freezing area from frost heaving, the construction space of the fiber modified stratum is larger than that of the freezing area, freezing pipes are arranged in the fiber modified stratum of the quasi-freezing area, then the freezing pipes are utilized to form the freezing area in the fiber modified stratum, and the fiber modified stratum effectively inhibits the influence of frost heaving deformation generated in the freezing area on the surrounding non-freezing area. The influence of frost heaving on the surrounding environment in the freezing process is effectively reduced, the effect of suppressing the influence of frost heaving deformation is good, the development speed of frozen soil can be increased by doping the steel fibers, the freezing time is shortened, the water content of the soil body and the flow of underground water can not be obviously changed by doping the steel fibers, the influence of an improved stratum on the soil body can be reduced, the underground environment is effectively protected, and the engineering cost is reduced.
Description
Technical Field
The invention relates to a method for inhibiting frost heaving deformation of a stratum, in particular to a method for inhibiting frost heaving deformation of a fiber improved stratum used in underground freezing construction, and belongs to the field of municipal underground engineering construction.
Background
In the underground engineering construction, when complex geological conditions such as a water-rich soft soil stratum and the like are met, the soil layer is often reinforced by adopting an artificial freezing technology, and the stratum performance is improved, so that the excavation and structure construction can be completed in the water-rich stratum. The frost heaving is a big disadvantage of the manual freezing method, if the frost heaving is controlled improperly, underground pipelines and foundations of adjacent buildings can be damaged, and even engineering accidents can happen in severe cases. Generally, most projects adopt methods of soil taking and pressure relief, intermittent starting of a freezing station, low-temperature brine flow control and the like to control the frost heaving amount, but the methods are passive control methods, only the increase of the frost heaving amount can be properly reduced, the frost heaving amount cannot be controlled from the source, and excessive methods of soil taking and pressure relief through drilling, low-temperature brine flow reduction and the like can cause great influence on an original soil layer and a frozen wall, so that the construction risk is increased.
In order to overcome the defects of passive control methods such as soil taking and pressure relief, domestic scholars propose a 'improving and freezing' method, which is a method for actively controlling frost heaving amount, namely inhibiting frost heaving from the source. In some projects in recent years, frost heaving is controlled by adopting a method of injecting cement into a soil layer, and a remarkable effect is achieved. The cement improved soil is characterized in that a certain amount of cement paste is mixed into the soil body by utilizing a cement deep mixing pile process in the range of freezing the soil body, and the cement and the water in the soil body are subjected to chemical reaction, so that the water in the soil body is reduced, the permeability coefficient of the stratum is reduced, and the aim of inhibiting frost heaving is fulfilled. However, the cement-modified soil has chemical action, is easy to pollute underground environment, and the modified stratum cannot be restored to the original state, particularly the restriction action of underground water, so that the process of agricultural production and the like is seriously influenced.
Disclosure of Invention
Aiming at the defects of the technology, the method for inhibiting frost heaving deformation of the fiber-improved stratum is simple in construction and low in cost, can effectively reduce the influence of stratum improvement on subsequent construction and agricultural production, and can reduce the influence of frost heaving on the surrounding environment in the freezing process, and can effectively inhibit frost heaving deformation in two aspects of frost heaving amount of a freezing area and deformation transmission amount of an unfrozen area, so that the influence of stratum frost heaving deformation on the ground in the freezing construction process is reduced.
In order to achieve the technical purpose, the method for inhibiting frost heaving deformation of the fiber improved stratum comprises the steps of constructing the fiber improved stratum in a to-be-frozen region, wherein the fiber improved stratum is formed by doping steel fibers into original soil particles, in order to prevent the frost heaving phenomenon of the frozen region, the construction space of the fiber improved stratum is larger than that of the frozen region, arranging freezing pipes in the fiber improved stratum in the to-be-frozen region, then forming the frozen region in the fiber improved stratum by utilizing the freezing pipes, and effectively inhibiting the influence of the frost heaving deformation generated in the frozen region on the surrounding non-frozen region of the fiber improved stratum.
The method comprises the following specific steps:
a. doping steel fibers in a preset freezing area below the underground water level and a surrounding stratum area thereof by a jet grouting reinforcement method to form a fiber-modified stratum wrapping the freezing area;
b. constructing a freezing pipe at a position of a to-be-frozen area in the fiber-modified stratum;
c. connecting a freezing system, and completing freezing construction of a freezing area by using a freezing pipe;
d. in the process of forming the frozen soil, the steel fibers doped into the stratum effectively improve the development speed of the frozen soil, and the cementing action between the steel fibers and the soil particles limits the displacement between the soil particles and the growth of ice lens bodies, so that the frost heaving amount of the frozen soil is reduced; steel fibers at the edge of the frozen soil and outside the frozen soil play a good water guiding role, so that the dissipation of pore water is accelerated, and the frost heaving deformation of the unfrozen soil stratum is reduced;
e. along with the development of frozen soil, the unfrozen area at the edge of the frozen wall is gradually changed into a frozen area, the water guide effect of the steel fibers in the unfrozen area in the fiber-modified stratum is also continuously changed into the cementing effect in the frozen wall, the frost heaving in the frozen soil is continuously limited, meanwhile, the steel fibers in the unfrozen area also continuously play a water guide effect, and the transfer effect of the frost heaving amount of the stratum is reduced.
When the thickness of the frozen wall meets the design requirement, the construction work of the excavation area below the frozen area can be carried out under the maintenance action of the frozen wall; after the construction of the excavation area is finished, the freezing is stopped, and the stratum can be recovered to the initial state after being unfrozen.
Before the fiber-improved stratum is constructed, the total mass of the fiber-improved stratum is estimated according to the space volume of the pre-constructed fiber-improved stratum, and then steel fibers with the mass ratio of 3% -5% are uniformly mixed into a construction area of the fiber-improved stratum in a jet grouting reinforcement mode, so that the fiber-improved stratum is completed.
The diameter of the steel fiber is 0.5-3 mm, and the length of the steel fiber is 5-30 mm.
Has the advantages that: the steel fiber is doped into the freezing area to form an improved stratum, so that the frost heaving amount of the freezing area is effectively reduced, the frost heaving deformation transmission of the unfrozen area is inhibited, the influence of frost heaving on the surrounding environment in the freezing process is reduced, the development speed of frozen soil can be increased by doping the steel fiber, the freezing time is shortened, the water content of a soil body and the flow of underground water can not be obviously changed by doping the steel fiber, the underground environment can be effectively protected, and the engineering cost is reduced. The freezing speed of the fiber-improved stratum is high, and the steel fibers enhance the constraint effect among soil particles, so that the frost heaviness of a freezing area is reduced; meanwhile, the steel fibers outside the freezing area increase the water guide channels of the unfrozen area, so that the dissipation of pore water is accelerated, the deformation of the unfrozen stratum around the freezing wall of the freezing area is reduced, and the influence of frost heaving deformation on the surrounding environment of the unfrozen area is inhibited.
Drawings
FIG. 1 is a schematic representation of the effectiveness of the practice of the present invention in fiber-upgrading a subterranean formation.
In the figure: 1-ground; 2-ground water level; 3-fiber-reinforced formation zones; 4-freezing the tube; 5-freezing area; 6-excavating an area;
Detailed Description
The following description of the embodiments refers to the accompanying drawings for illustrating the specific embodiments in which the invention may be practiced.
As shown in figure 1, the method for inhibiting frost heaving deformation of a fiber-modified stratum of the invention comprises the following main construction steps that underground water exists below the ground 1 of a certain urban area, when an excavation area 6 needs to be constructed below an underground water level 2, because the underground water is abundant, a soil layer is reinforced and supported by adopting an artificial freezing method, the range of a freezing area 5 is designed, and in order to reduce the influence of frost heaving deformation on the surrounding environment in the freezing process, the stratum of the steel fiber-modified freezing area 5 is doped to inhibit the frost heaving amount of the stratum: the fiber-modified stratum 3 is constructed in a quasi-freezing area, the fiber-modified stratum 3 is formed by original soil particle mixed steel fibers, in order to prevent the freezing area from frost heaving, the construction space of the fiber-modified stratum 3 is larger than that of the freezing area, a freezing pipe 4 is arranged in the fiber-modified stratum 3 of the quasi-freezing area, then a freezing area 5 is formed in the fiber-modified stratum 3 by the freezing pipe 4, and the fiber-modified stratum 3 effectively inhibits the influence of frost heaving deformation generated in the freezing area 5 on the surrounding non-freezing area.
The method comprises the following specific steps:
a. doping steel fibers into a freezing area 5 preset below the underground water level 2 and a zone 3 of a stratum around the freezing area 5 by a jet grouting reinforcement method to form a fiber modified stratum 4 wrapping the freezing area 5;
specifically, before constructing the fiber-modified stratum 3, estimating the total mass of the fiber-modified stratum 3 according to the space volume of the pre-constructed fiber-modified stratum 3, and then uniformly doping 3-5% of steel fibers into a construction area of the fiber-modified stratum 3 in a mass ratio by a jet grouting reinforcement mode, wherein the diameter of the steel fibers is 0.5-3 mm, and the length of the steel fibers is 5-30 mm, so as to finish the fiber-modified stratum 3;
b. constructing a freezing pipe 4 at a position of a to-be-frozen area in the fiber-modified stratum 4;
c. the freezing system is connected, and the freezing construction of the freezing area 5 is completed by using the freezing pipe 4;
d. in the process of forming the frozen soil, the steel fibers doped into the stratum effectively improve the development speed of the frozen soil, and the cementing action between the steel fibers and the soil particles limits the displacement between the soil particles and the growth of ice lens bodies, so that the frost heaving amount of the frozen soil is reduced; steel fibers at the edge of the frozen soil and outside the frozen soil play a good water guiding role, so that the dissipation of pore water is accelerated, and the frost heaving deformation of the unfrozen soil stratum is reduced;
e. with the development of frozen soil, the unfrozen area at the edge of the frozen wall is gradually changed into a frozen area, the water guide effect of the steel fibers in the unfrozen area in the fiber modified stratum 3 is also continuously changed into the cementing effect in the frozen wall, the frost heaving in the frozen soil is continuously limited, meanwhile, the steel fibers in the unfrozen area also continuously play a water guide effect, and the transfer effect of the formation frost heaving amount is reduced;
f. when the thickness of the frozen wall meets the design requirement, the construction work of the excavation region 6 below the frozen region 5 can be carried out under the maintenance action of the frozen wall;
g. after the construction of the excavation area 6 is finished, the freezing is stopped, and the stratum can be recovered to the initial state after being unfrozen.
Claims (5)
1. A method of inhibiting frost heave deformation in a fiber-modified formation, comprising: the fiber-modified stratum (3) is constructed in a quasi-freezing area, the fiber-modified stratum (3) is formed by modifying original soil particles by doping steel fibers, in order to prevent a frost heaving phenomenon in the freezing area, the construction space of the fiber-modified stratum (3) is larger than that of the freezing area, freezing pipes (4) are arranged in the fiber-modified stratum (3) in the quasi-freezing area, then freezing areas (5) are formed in the fiber-modified stratum (3) by utilizing the freezing pipes (4), and the fiber-modified stratum (3) effectively inhibits the influence of frost heaving deformation generated by the freezing areas (5) on surrounding non-freezing areas.
2. The method for inhibiting frost heave deformation in a fiber-modified stratum according to claim 1, comprising the following steps:
a. steel fibers are doped into a freezing area (5) preset below the underground water level (2) and an area (3) of a stratum around the freezing area by a jet grouting reinforcement method to form a fiber modified stratum (4) wrapping the freezing area (5);
b. constructing a freezing pipe (4) at a position of a to-be-frozen area in the fiber-modified stratum (4);
c. the freezing system is connected, and freezing construction of the freezing area (5) is completed by using the freezing pipe (4);
d. in the process of forming the frozen soil, the steel fibers doped into the stratum effectively improve the development speed of the frozen soil, and the cementing action between the steel fibers and the soil particles limits the displacement between the soil particles and the growth of ice lens bodies, so that the frost heaving amount of the frozen soil is reduced; steel fibers at the edge of the frozen soil and outside the frozen soil play a good water guiding role, so that the dissipation of pore water is accelerated, and the frost heaving deformation of the unfrozen soil stratum is reduced;
e. along with the development of frozen soil, the unfrozen area at the edge of the frozen wall is gradually changed into a frozen area, the water guide effect of the steel fibers in the unfrozen area in the fiber modified stratum (3) is also continuously changed into the cementing effect in the frozen wall, the frost heaving in the frozen soil is continuously limited, meanwhile, the steel fibers in the unfrozen area also continuously play the water guide effect, and the transfer effect of the formation frost heaving amount is reduced.
3. The method of inhibiting frost heave deformation in a fiber-modified formation of claim 2, wherein: when the thickness of the frozen wall meets the design requirement, the construction work of the excavation region (6) below the frozen region (5) can be carried out under the maintenance action of the frozen wall; after the construction of the excavation area (6) is finished, the freezing is stopped, and the stratum can be recovered to the initial state after being unfrozen.
4. The method of inhibiting frost heave deformation in a fiber-modified formation of claim 2, wherein: before the fiber-modified stratum (3) is constructed, the total mass of the fiber-modified stratum (3) is estimated according to the space volume of the pre-constructed fiber-modified stratum (3), and then steel fibers with the mass ratio of 3% -5% are uniformly mixed into the construction area of the fiber-modified stratum (3) in a jet grouting reinforcement mode, so that the fiber-modified stratum (3) is completed.
5. The method of inhibiting frost heave deformation in a fiber-modified formation of claim 1, wherein: the diameter of the steel fiber is 0.5-3 mm, and the length of the steel fiber is 5-30 mm.
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| CN113756816A (en) * | 2021-08-25 | 2021-12-07 | 上海市机械施工集团有限公司 | Method for controlling frost heaving of shallow soil |
| CN114351528A (en) * | 2021-12-01 | 2022-04-15 | 北京中煤矿山工程有限公司 | High-pressure slurry jet hole cutting and frost heaving reduction construction method |
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