CN109781962B - Salt-frost heaving double control-based high-speed railway salinized soil roadbed partition layer design method - Google Patents
Salt-frost heaving double control-based high-speed railway salinized soil roadbed partition layer design method Download PDFInfo
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Abstract
The method for designing the high-speed railway salinized soil roadbed partition layer based on salt-frost heaving double control is used for scientifically and reasonably determining the design of the high-speed railway salinized soil roadbed partition layer, is convenient and fast to implement, has clear flow and can well meet the requirements of actual engineering construction. The method comprises the following steps: determining the temperature difference delta t of different depths h below the top surface of the saline soil subgrade with the duration of not less than 1 year through on-site in-situ monitoring, and drawing a delta t-h graph; taking the depth corresponding to the delta T ═ delta T in the delta T-h graph as the depth ht of the environmental temperature sensitive layer of the salinized soil roadbed; determining the salt expansion force F of different depths h below the top surface of the roadbed through a salinized soil salt expansion test, and drawing an F-h graph; taking the depth corresponding to F-W in the F-h graph as the critical balance depth hF of the salt expansion force; determining the minimum setting depth [ h ] of the high-speed railway coarse-particle saline soil embankment partition layer; and finally determining the reasonable embedding depth h of the high-speed railway saline soil roadbed partition layer by combining the structural design of the high-speed railway roadbed foundation bed in the saline soil area.
Description
Technical Field
The invention relates to the technical field of geotechnical engineering, in particular to a design method of a high-speed railway saline soil subgrade partition layer.
Background
The saline soil has the characteristics of salt expansion and solution collapse, and the risk of frost heaving exists, so when the high-speed railway is built in the saline land area, the current specification requires that the saline soil cannot be used as roadbed filling, and the problem of filling for building the high-speed railway in the saline land area is very prominent.
Through scientific research, when the content of fine particles and the content of soluble salt are well controlled, the coarse-particle saline soil can be used for the high-speed railway roadbed filling, but improvement on the roadbed structure is needed, and the design of a partition layer is also needed to be improved. The reasonable setting depth of the partition layer influences the migration path and mode of moisture and salt in the whole roadbed range, and further influences the long-term salt-frost heaving deformation and damage of the high-speed railway roadbed in the saline soil area.
At present, the 'railway special roadbed design specification' makes a regulation on the content of soluble salt in a salinized soil roadbed filler, makes a simple regulation on the application conditions of a partition layer, and the position of the designed partition layer depends on experience mostly, so that no clear related design theory of the salinized soil roadbed partition layer of the high-speed railway is seen. Therefore, the design of the high-speed railway subgrade in the saline soil area urgently needs to provide a method for designing the high-speed railway saline soil subgrade partition layer.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for designing a high-speed railway salinized soil roadbed partition layer based on salt-frost heaving double control, so that the design of the high-speed railway salinized soil roadbed partition layer is scientifically and reasonably determined, the implementation is convenient, the flow is clear, and the method can well meet the requirements of actual engineering construction.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention relates to a method for designing a high-speed railway salinized soil roadbed partition layer based on salt-frost heaving double control, which comprises the following steps of:
(1) determining the temperature difference delta t of different depths h below the top surface of the saline soil subgrade with the duration of not less than 1 year through on-site in-situ monitoring, and drawing a delta t-h graph with the abscissa as the temperature difference delta t and the ordinate as the depth h;
(2) taking the depth corresponding to the delta T = [ delta T ] in the delta T-h graph in the step (1) as the depth ht of the environmental temperature sensitive layer of the salinized soil subgrade;
(3) determining the salt expansion force F of different depths h below the top surface of the roadbed through a salt expansion test of saline soil, and drawing an F-h graph with the abscissa as the salt expansion force F and the ordinate as the depth h;
(4) taking the depth corresponding to F = W in the F-h graph in the step (3) as the critical balance depth h of the salt expansion forceF ；
(5) Determining the minimum setting depth [ h ] of the coarse grain salinized soil roadbed partition layer of the high-speed railway according to the following formula:
[h]=max{hF，ht}
wherein [ h ]]The minimum setting depth h of the coarse grain salinized soil roadbed partition layer of the high-speed railwaytIs the depth of an environmental temperature sensitive layer h of a salinized soil roadbedFThe critical equilibrium depth of salt expansion force;
(6) and (5) according to the calculation result of the step (5), and by combining with the structural design of the high-speed railway subgrade bed in the saline soil area, carrying out easy implementation, rationality and economic analysis, and finally determining the reasonable embedding depth h of the high-speed railway saline soil subgrade partition layer.
In the steps (1) and (2), the depth h of the environmental temperature sensitive layer of the salinized soil roadbedtIs Δ T = [ Δ T ] in a diagram of Δ T-h]Corresponding depth, delta t is the lowest temperature t of different depth saline soil layers of the top surface of the roadbed in one yearminAnd the maximum temperature tmaxTemperature difference of [ Delta T ]]Determined by combining the observation data of the regional temperature with the indoor freeze-thaw cycle test, when no regional experience exists, [ delta T [ [ delta ] T [ ]]Taking the mixture at 6-9 ℃;
in the steps (3) and (4), the critical balance depth h of salt expansion forceFThe depth corresponding to F = W in the F-h diagram, W is the overlying filling pressure, W = gamma multiplied by h1, wherein gamma is the volume weight of the overlying saline soil, and h1 is the thickness of the overlying saline soil.
The method has the advantages that the reasonable design position of the high-speed railway salinized soil roadbed partition layer can be determined through the depth of the environmental temperature sensitive layer in the salinized soil area and the curve that the salt expansion force changes along with the depth, and a basis is provided for the design of the high-speed railway roadbed in the salinized soil area.
Drawings
FIG. 1 is a diagram of a curve delta t-h of the variation of the temperature difference of the salinized soil subgrade of the high-speed railway with the depth in the embodiment of the invention.
FIG. 2 is a F-h graph of the salt expansion force of the salinized soil subgrade of the high-speed railway along with the change of the depth in the embodiment of the invention.
FIG. 3 is a diagram of the arrangement position of a salt-frost heaving double control-based high-speed railway salinized soil subgrade partition layer in the embodiment of the invention. In the figure, the reference numeral 1 is a surface layer of a foundation bed, 2 is an upper bottom layer of the foundation bed, 3 is a lower bottom layer of the foundation bed, 4 is a roadbed below the foundation bed, and 5 is a partition layer.
Detailed Description
The invention is further illustrated by the following specific examples in conjunction with the accompanying drawings.
The invention relates to a method for designing a salt-frost heaving double control-based high-speed railway salinized soil roadbed partition layer, which comprises the following steps of:
(1) determining the temperature difference delta t (unit: DEG C) of different depths h (unit: m) below the top surface of the saline soil subgrade with the duration of not less than 1 year through on-site in-situ monitoring, and drawing a delta t-h graph with the abscissa as the temperature difference delta t and the ordinate as the depth h;
(2) taking the depth corresponding to delta T = [ delta T ] in the delta T-h graph in the step (1) as the depth ht (unit: m) of the environmental temperature sensitive layer of the salinized soil subgrade;
(3) determining the salt expansion force F (unit: m) at different depths h (unit: m) below the top surface of the roadbed through a salt expansion test of saline soil, and drawing an F-h graph with the abscissa as the salt expansion force F and the ordinate as the depth h;
(4) taking the depth corresponding to F = W in the F-h graph in the step (3) as the critical balance depth h of the salt expansion forceF(unit: m);
(5) determining the minimum setting depth [ h ] of the coarse grain salinized soil roadbed partition layer of the high-speed railway according to the following formula:
[h]=max{hF，ht}
wherein [ h ]]Is coarse-grained salt for high-speed railwayMinimum setting depth (unit: m) of soil-affected subgrade partition layer, htThe depth (unit: m) of the environmental temperature sensitive layer of the salinized soil roadbed is hFCritical equilibrium depth of salt expansion force (unit: m);
(6) and (5) according to the calculation result of the step (5), and by combining with the structural design of the high-speed railway subgrade bed in the saline soil area, carrying out easy implementation, rationality and economic analysis, and finally determining the reasonable embedding depth h (unit: m) of the high-speed railway saline soil subgrade partition layer.
In the step (1), the temperature difference delta t is the lowest temperature t of saline soil layers with different depths below the top surface of the roadbed in one yearminAnd the maximum temperature tmaxThe temperature difference is determined according to the in-situ monitoring data of the regional field temperature.
In the step (2), [ Delta T ] is determined by combining the regional temperature observation data with the indoor freeze-thaw cycle test, and when no regional experience exists, [ Delta T ] can be 6-9 ℃.
In the step (4), W is the overlying filling pressure, namely W = gamma multiplied by h1, wherein gamma is the unit weight of the overlying saline soil (unit: kN/m)3) And h1 is the thickness of the overlying saline soil (unit: m).
In the steps (1) to (5), the depth h of the environmental temperature sensitive layer of the salinized soil subgrade is determinedtCritical equilibrium depth h of salt swell forceFDetermining the minimum setting depth [ h ] of the coarse grain salinized soil roadbed partition layer of the high-speed railway]。
Example (b):
a high-speed railway ballastless track railway subgrade in a certain saline land area is filled to a height of 5m, the top surface width is 13.6m, and the side slope ratio is 1: 1.5. The method for determining the arrangement position of the partition layer of the coarse-grained saline soil high-speed railway roadbed comprises the following specific steps:
(1) determining the temperature difference delta t of different depths h below the top surface of the saline soil subgrade with the duration of not less than 1 year through on-site in-situ monitoring, and drawing a delta t-h graph with the abscissa as the temperature difference delta t and the ordinate as the depth h;
(2) taking the depth corresponding to the delta T = [ delta T ] in the delta T-h graph in the step (1) as the depth ht of the environmental temperature sensitive layer of the salinized soil subgrade, and taking the [ delta T ] =9 ℃ and ht =1.18m as shown in the graph 1;
(3) determining the salt expansion force F (unit: m) at different depths h (unit: m) below the top surface of the roadbed through a salt expansion test of saline soil, and drawing an F-h graph with the abscissa as the salt expansion force F and the ordinate as the depth h;
(4) taking the depth corresponding to F = W in the F-h graph in the step (3) as the critical balance depth h of the salt expansion forceFWherein gamma is 2100kg/cm3, hF=1.36m, as shown in fig. 2;
(5) according to [ h]=max{ hF，ht= max {1.56, 1.18} =1.36m, and the minimum setting depth [ h ] of the high-speed railway coarse-particle salinized soil roadbed partition layer can be obtained]=1.36m。
(6) According to the high-speed rail design specification, the high-speed rail foundation bed can be divided into a foundation bed surface layer 1 and a foundation bed bottom layer, wherein the thickness of the foundation bed surface layer 1 is 0.4m, and the thickness of the foundation bed bottom layer is 2.3 m. If partition layer 5 sets up between foundation bed top layer 1 and foundation bed top 2, then unsatisfied the minimum depth of setting that step (5) obtained, if set up in foundation bed bottom 3 lower part, not only the width is wide, and the salt content of foundation bed bottom within range up migration easily moreover can only be to the salt content strict control of whole foundation bed bottom, and this is higher to the filler demand in salinized soil area, and economic nature is also relatively poor. Therefore, in the salinized soil area, the roadbed is divided into an upper basement layer 2 and a lower basement layer 3, the thickness of the upper basement layer 2 of the basement is 1.0m, coarse-grained salinized soil with the soluble salt content of less than 1.5% is adopted for filling, the thickness of the lower basement layer 3 of the basement is 1.3m, coarse-grained salinized soil with the soluble salt content of less than 3% is adopted for filling, and the reasonable position of the upper partition layer 5 of the salinized soil roadbed of the high-speed railway is the interface between the upper basement layer 2 of the basement and the lower basement layer 3 of the basement, namely the depth is 1.4m, as shown in figure 3.
The above description is only used for illustrating some principles of the method for designing the salt-frost heaving double control-based high-speed railway salinized soil roadbed partition layer of the invention, and the invention is not limited to the specific method and the application range shown and described, so all the corresponding modifications and equivalents which can be utilized belong to the patent scope applied by the invention.
Claims (2)
1. The method for designing the high-speed railway salinized soil roadbed partition layer based on salt-frost heaving double control comprises the following steps:
(1) determining the temperature difference delta t of different depths h below the top surface of the saline soil subgrade with the duration of not less than 1 year through on-site in-situ monitoring, and drawing a delta t-h graph with the abscissa as the temperature difference delta t and the ordinate as the depth h;
(2) taking the depth corresponding to the delta T = [ delta T ] in the delta T-h graph in the step (1) as the depth ht of the environmental temperature sensitive layer of the salinized soil subgrade;
(3) determining the salt expansion force F of different depths h below the top surface of the roadbed through a salt expansion test of saline soil, and drawing an F-h graph with the abscissa as the salt expansion force F and the ordinate as the depth h;
(4) taking the depth corresponding to F = W in the F-h graph in the step (3) as the critical balance depth h of the salt expansion forceF ；
(5) Determining the minimum setting depth [ h ] of the coarse grain salinized soil roadbed partition layer of the high-speed railway according to the following formula:
[h]=max{hF，ht}
wherein [ h ]]The minimum setting depth h of the coarse grain salinized soil roadbed partition layer of the high-speed railwaytIs the depth of an environmental temperature sensitive layer h of a salinized soil roadbedFThe critical equilibrium depth of salt expansion force;
(6) according to the calculation result of the step (5), and by combining with the structural design of the high-speed railway subgrade bed in the saline soil area, carrying out easy implementation, rationality and economic analysis, and finally determining the reasonable embedding depth h of the high-speed railway saline soil subgrade partition layer;
in the steps (1) and (2), the depth h of the environmental temperature sensitive layer of the salinized soil roadbedtIs Δ T = [ Δ T ] in a diagram of Δ T-h]Corresponding depth, delta t is the lowest temperature t of different depth saline soil layers of the top surface of the roadbed in one yearminAnd the maximum temperature tmaxTemperature difference of [ Delta T ]]According toThe regional temperature observation data is determined by combining the indoor freeze-thaw cycle test, and when no regional experience exists, [ delta T [ delta ] T [, T [ ]]Taking the mixture at 6-9 ℃;
in the steps (3) and (4), the salt expansion critical force balance depth hFThe depth corresponding to F = W in the F-h diagram, W is the overlying filling pressure, W = gamma multiplied by h1, wherein gamma is the volume weight of the overlying saline soil, and h1 is the thickness of the overlying saline soil.
2. The method for designing the salt-frost heaving double control-based high-speed railway salinized soil roadbed partition layer as claimed in claim 1, wherein the method comprises the following steps: in the steps (1) to (5), the depth h of the environmental temperature sensitive layer of the salinized soil subgrade is determinedtCritical equilibrium depth h of salt swell forceFDetermining the minimum setting depth [ h ] of the coarse grain salinized soil roadbed partition layer of the high-speed railway]。
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| CN104250946A (en) * | 2014-10-11 | 2014-12-31 | 中铁第四勘察设计院集团有限公司 | High-speed railway subgrade structure for saline soil areas |
| CN106592346B (en) * | 2017-01-22 | 2018-11-23 | 中铁二院工程集团有限责任公司 | In-strong saline soil area headchute partition-type non-fragment orbit cutting foundation bed structure |
| CN206800076U (en) * | 2017-01-22 | 2017-12-26 | 中铁二院工程集团有限责任公司 | Saline soil area high-speed railway embankment reinforcing construction |
| CN107632139A (en) * | 2017-10-17 | 2018-01-26 | 中交第公路勘察设计研究院有限公司 | Consider each salt marsh earth salt expansive force test device and usage to confined pressure |
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| CN108930294B (en) * | 2018-07-24 | 2020-04-17 | 中铁二院工程集团有限责任公司 | Method for determining uplift amount of low-embankment-base saline soil pile foundation after reinforcement |
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