A kind of method of utilizing steel slag to fill highway subgrade
Technical field
The present invention relates to fill highway subgrade, more specifically relate to a kind of method of utilizing steel slag to fill highway subgrade.
Background technology
In the construction of filling highway subgrade, utilizing steel slag to fill highway subgrade is a kind of new method, can reduce slag and stack place and environment pollution, turns waste into wealth, and promotes environmental protection, solves the not enough problem of highway engineering filler, reduces construction costs.
Shanghai municipal sector once utilized vessel slag to carry out the test of causeway base course in the sixties in 20th century, but because slag did not process at that time, free calcium oxide f-CaO and magnesia MgO composition are higher in the slag, cause the unstability of filling body volume, the application of slag in road is restricted.Wuhan Iron and Steel Plant was carried out the Wuhan Iron and Steel Plant slag and was done the research work of foundation backfill material test in 1988.Because slag has its special relatively physical and mechanical property, some not success is attempted in some application of once carrying out, heaves cracking, foundation expansion, mill construction destruction etc. as terrace, causes and applies slowly.The comprehensive utilizating research of slag aspect road puts more effort in recent years, and oneself has certain achievement in research both at home and abroad, all is that it is used as the roadbed backfilling material mostly, or replaces rubble in the road compound simply as aggregate.People are utilizing steel slag to fill highway subgrade, particularly fill highway embankment, also do not have perfect method.
Summary of the invention
The objective of the invention is to be to provide a kind of method of utilizing steel slag to fill highway subgrade, easy to implement the method, easy to operate, adopting necessarily required steel slag and cohesive soil is main stuffing, can satisfy the construction quality requirement of filling highway subgrade and embankment, cost is low, and subgrade stability is reliable.
To achieve these goals, the present invention has adopted following technical scheme: a kind of method of utilizing steel slag to fill highway subgrade, be characterized in, and be main stuffing with steel slag and the cohesive soil that meets certain requirements, may further comprise the steps:
A, filling roadbedly select materials with slag
Subgrade construction has strict requirement to the filling material quality, and therefore the safety of problem entail dangers to roadbeds such as slag expansion efflorescence want strict every index of controlling slag:
(1) new slag must not be used or sneak into, the steel slag of storing up more than a year should be adopted.Be used for filling roadbed slag maximum particle diameter and should be not more than 40mm (square hole), particle diameter should not surpass 40% greater than the granule content of 20mm.Slag mass percent by particle diameter sees Table 1.Coarse fodder must not take place when filling concentrate built on stilts phenomenon.
Suggestion grading limit (the percent of pass: mass percent %) of table 1 slag
(2), should satisfy the following regulation of on-the-spot filler CBR value for express highway roadbed: the following degree of depth 0~0.3m in bottom surface, road surface, more than or equal to 8%; The following degree of depth 0.3~0.8m in bottom surface, road surface is more than or equal to 5%; The following degree of depth 0.8~1.5m in bottom surface, road surface is more than or equal to 4%; Below the following degree of depth 1.5m in bottom surface, road surface, more than or equal to 3%.
(3) slag crush values: roadbase slag crush values should be less than 30%.Such aggregate strength height, soundness is good, the modulus of elasticity height.
(4) slag stability: building the road with slag is that process ageing or other method (as through hot application slag technology and crushing-magnetic selection) are handled stable slag, should guarantee to decompose and stablize, and f-CaO content answers<3%; (the fluctuation upper limit of 91~110kPa) boiling pulverization rate measured values is no more than 5% to normal pressure; Should remove rubbish and objectionable impurities.
(5) slag quality coefficient: the slag quality coefficient should be greater than 1.2, in the slag average of compounds such as manganese, titanium, sulphur all within the setting (as MgO content in 9%, TiO
2Content is below 1%, and sulfur content is below 0.6%).
Slag is stacked the place, should strengthen the division management of the old and new's slag, delimits special production zone, and the special train haul is avoided other slag to mix transporting to the building site influence roadbed filling quality, will carry out random inspection to the slag of transporting to engineering site and check.
B, fill speed:
The slag of controlling well is filling roadbed fills speed, can guarantee the stability of roadbed.Slag also is that foundation soil is fixed, the process of gain in strength in the filling construction process, along with the continuous growth of consolidation strength, could guarantee to bear ever-increasing upper load.The slag railway embankment using is slow more, and is favourable more to the stability of ground, but the highway construction duration requires the time of filling short more good more again.Therefore, should guarantee the duration, also will guarantee workmanship, must propose the problem that slag fills speed.The speed of filling of filling roadbed each layer of slag is 5~8 days, will cooperate highway to detect data simultaneously and control, and strengthens the monitoring of process that slag is filled, and obtains full and accurate monitored data and comes guiding construction.
C, the filling roadbed compacting of slag:
At first be that slag after paving must in time roll, slag should be in the optimum moisture content scope when rolling.Next is that the slag embankment is answered placement in layers, adopts the vibratory roller layered rolling.Determine suitable to roll facility, roll mode and corresponding degree of compaction with the method for routine test highway section test, the degree of compaction of slag roadbed should be not less than 90%.The 3rd is to adopt maximum dry density and optimum moisture content as the filling roadbed degree of compaction basis of calculation of slag.Select representational sample to carry out compaction test, determine maximum dry density and optimum moisture content to survey.The factor that the lamination solidity is filled in influence has varied, such as compactibility, water content, the loose laying depth of filler, and the compacting machinary that adopts of construction and compacting functions etc., all will produce influence in various degree to the degree of compaction of filling layer.If slag filler grating good the suggestion grading limit of table 1 slag (as meet) and be in optimum moisture content, then slag is easy to compacting.The maximum dry density scope of described slag is 2.3g/cm
3~2.6g/cm
3, the optimum moisture content scope is 6.0%~9.0%.
D, slag embankment cross-sectional design:
Designs such as slag embankment cross-sectional design mainly comprises side slope of embankment ratio of slope, depth of fill, fills bed thickness, closedtop layer, underseal layer, interlayer, bank protection, drainage system and cross section.
(1) depth of fill and side slope ratio of slope
The height H of slag railway embankment using generally is not more than 5m, requires natural ground soil allowable bearing [σ] greater than 192kPa simultaneously, if allowable bearing does not reach requirement, then should adopt change fill out, treatment measures such as powder spray piling reinforcing.The railway embankment using ratio of slope is 1:1.5, and the side slope ratio of slope of immerseable embankment below design water level is 1: 1.75.
(2) fill bed thickness
The layer thickness control of filling of slag is important measures that guarantee the filling roadbed quality of slag.To heavy compacting machinary, the layering loose laying depth is 30cm, and should adjust according to test section compacting testing result.Also bed thickness can be reduced, to guarantee compaction quality.Ram vibration at small-sized electric and tamp under 3 times the situation, the degree of compaction the when compacted depth of slag is 15cm can reach about 85%.
(3) closedtop layer, underseal layer, interlayer
25~35cm is provided with the soil property layer that binds below road surface structare layer, adopts road surface base layer materials such as rendzinas, two-ash soil or three dirt to make to bind layer.When natural ground is an expansive soil foundation, then should adopt expansive soil foundation slag embankment cross-sectional design figure.For soft foundation and expansion roadbed, immerse ground for preventing road surface flow water, in steel embankment bottom the thick back cover layer of 45~55cm should be set.After natural ground handled through necessary reinforcing, leveling, should adopt index of plasticity to be not less than 6 cohesive soil, should overlay geo-grid on the local inhomogeneous ground.When natural ground is a soft foundation, then should adopt soft foundation slag embankment cross-sectional design figure.Natural ground through after necessary ground processing and flattening, is filled the slag roadbed again.When the slag depth of fill surpasses 4m, should the thick interlayer of 55~65cm together be set at the embankment middle part, interlayer adopts cohesive soil to fill.The every increase of slag embankment 2m then is provided with the cohesive soil interlayer one.Interlayer not only can stop the upper strata rainwater infiltration, can also absorb the swelling stress of slag embankment, reduces or avoids slag to expand to the destruction of embankment.Require not contain foreign material in the clay, compacting under optimum moisture content, loose laying depth and degree of compaction will reach the requirement of relevant road quality classification standard.
(4) bank protection
Side slope of embankment (10,11) and curb are taked the measure of soil property bank protection edge protection.Bank protection earth material employing index of plasticity is not less than 6 clay soil.The width of soil property bank protection is no less than 2m for the roadbed both sides, and the gradient is identical with the slag embankment gradient.In the soil property bank protection, weeper drain is set.The french drain cross dimensions is 40cm * 50cm, level interval 10~15m, and vertical interval 1.0~1.5m is quincunx arranged crosswise, the flare gradient 10%.When there is the water logging bubble embankment both sides, should adopt barricade and mortar bank protection, stop water to permeate to the slag embankment.When the anhydrous immersion in embankment both sides, can adopt the grid bank protection, turfing on the slope, engineering protection combines with biological protection.
The compacting of soil property bank protection will be constructed simultaneously with embankment, large-scale compacting machinary roll less than the place, tamp with small-sized machine.
When filled-up ground is subjected to terrain and its features restriction or subgrade stability deficiency, can adopt the spats roadbed.The spats height should not surpass 4m, and the embankment spats that flooded by water logging should protect or reinforce.
(5) drainage system
Construction period, answer drainage trenching, in roadbed inside weeper drain to be set.When construction rolls, horizontal wall inscription should be set, be beneficial to rainwater and be discharged to the embankment both sides, during embankment fills horizontal wall inscription and longitudinal gradient will be set, the horizontal wall inscription gradient is controlled at 1.5%~5.0%, and the longitudinal gradient gradient is controlled at 0.3%~3.0%.Trapezoidal gutter is established in the embankment both sides, wide 180cm suitable for reading, the wide 60cm of end opening; The excavation highway section is established rectangle and is added a cover the edges of boards ditch, and landform is smooth, longitudinal gradient is mild lowly fills out, dish-like ditch is established in the shallow cut highway section; Trapezoidal catchwater is established in the big highway section of catchment area outside top, cutting slope.The road surface hydromining enters gutter or gutter with the mode of cross flow, water is concentrated to enter in the natural irrigation canals and ditches again.Gutter adopts cemented rock to build by laying bricks or stones, and mortar adopts the M7.5 mortar, and cemented rock thickness is 250cm.The position of carrying out import and export is selected and is handled, phenomenon such as prevent obstruction, overflow, seepage, deposit, wash away and freeze.The gutter bottom of trench longitudinal gradient gradient should be consistent with gradient incline, and be not less than 0.3%.The current of surface drainage ditch tube drainage can be discharged into the sedimentation basin post precipitation earlier and be discharged to outside the roadbed.Catchwater should be provided with according to orographic condition and catchment area etc.The moat top catchwater of excavation roadbed should be arranged on beyond the groove 5m, and should lay in conjunction with landform.The embankment catchwater of filled-up ground upside should be not less than 2m apart from the distance of fill toe.In the area of heavy rainfull, look actual conditions and can establish one or multi-channel catchwater.The catchwater form of fracture should be determined in conjunction with position, displacement, landform and side slope situation are set, cut the bottom of trench longitudinal gradient and be not less than 0.3%.
The present invention compared with prior art has following major advantage: 1. reduce the stacking place and the environment pollution of slag, turn waste into wealth, promote environmental protection; 2. solve the not enough problem of highway engineering filler; 3. with low cost; 4. subgrade stability is reliable.
Description of drawings
Fig. 1 is a kind of method standard schematic cross-sectional view of utilizing steel slag to fill highway subgrade;
Fig. 2 is a kind of method expansive soil foundation slag embankment schematic cross-sectional view of utilizing steel slag to fill highway subgrade;
Fig. 3 is a kind of method soft foundation slag embankment schematic cross-sectional view of utilizing steel slag to fill highway subgrade.
Among the figure: the roadbed after 1-leveling is handled; 2-slag embankment; 3-M7.5 mortar building block stone; 4-french drain; 5-interlayer, thick 55~65cm; 6-soil property bank protection; 7-layer binds; 8-underseal layer; 9-excavate weak soil and change the roadbed of filling out after the leveling, 10-bank protection ratio of slope 1: 1.75,11-bank protection ratio of slope 1:1.5.
The specific embodiment
The invention will be further described below in conjunction with accompanying drawing.
A kind of method of utilizing steel slag to fill highway subgrade the steps include:
A, filling roadbedly select materials with slag
Subgrade construction has strict requirement to the filling material quality, and therefore the safety of problem entail dangers to roadbeds such as slag expansion efflorescence want strict every index of controlling slag:
(1) new slag must not be used or sneak into, the steel slag of storing up more than a year should be adopted.Be used for filling roadbed slag maximum particle diameter and should be not more than 40mm (square hole), particle diameter should not surpass 40% greater than the granule content of 20mm.Should adopt the suggestion grading limit of table 1.Coarse fodder must not take place when filling concentrate built on stilts phenomenon.
Suggestion grading limit (the percent of pass: mass percent %) of table 1 slag
(2), should satisfy the following regulation of on-the-spot CBR value for express highway roadbed: the following degree of depth 0~0.3m in bottom surface, road surface, more than or equal to 8%; The following degree of depth 0.3~0.8m in bottom surface, road surface is more than or equal to 5%; The following degree of depth 0.8~1.5m in bottom surface, road surface is more than or equal to 4%; Below the following degree of depth 1.5m in bottom surface, road surface, more than or equal to 3%.
(3) slag crush values: roadbase slag crush values should be less than 30%.Such aggregate strength height, soundness is good, the modulus of elasticity height.
(4) slag stability: building the road with slag is that process ageing or other method (as through hot application slag technology and crushing-magnetic selection) are handled stable slag, should guarantee to decompose and stablize, and f-CaO content answers<3%; (the fluctuation upper limit of 91~110kPa) boiling pulverization rate measured values is no more than 5% to normal pressure; Should remove rubbish and objectionable impurities (as the magnesia brick etc. that gives up).
(5) the slag quality coefficient should be greater than 1.2, in the slag average of compounds such as manganese, titanium, sulphur all within the setting (as MgO content in 9%, TiO
2Content is below 1%, and sulfur content is below 0.6%).
Slag is stacked the place, should strengthen the division management of the old and new's slag, delimits special production zone, and the special train haul is avoided other slag to mix transporting to the building site influence roadbed filling quality, will carry out random inspection to the slag of transporting to engineering site and check.
B, fill speed
The slag of controlling well is filling roadbed fills speed, can guarantee the stability of roadbed.Slag also is that foundation soil is fixed, the process of gain in strength in the filling construction process, along with the continuous growth of consolidation strength, could guarantee to bear ever-increasing upper load.The slag railway embankment using is slow more, and is favourable more to the stability of ground, but the highway construction duration requires the time of filling short more good more again.Therefore, should guarantee the duration, also will guarantee workmanship, must propose the problem that slag fills speed.The speed of filling of filling roadbed each layer of slag is 5~8 days, will cooperate highway to detect data simultaneously and control, and strengthens the monitoring of process that slag is filled, and obtains full and accurate monitored data and comes guiding construction.
C, the filling roadbed compacting of slag
Slag after paving must in time roll, and slag should be in the optimum moisture content scope when rolling.The slag embankment is answered placement in layers, adopts the vibratory roller layered rolling.Determine suitable to roll facility, roll mode and corresponding degree of compaction with the method for routine test highway section test, the degree of compaction of slag roadbed should be not less than 90%.
Adopt maximum dry density and optimum moisture content as the filling roadbed degree of compaction basis of calculation of slag.Select representational sample to carry out compaction test, determine maximum dry density and optimum moisture content to survey.The factor that the lamination solidity is filled in influence has varied, such as compactibility, water content, the loose laying depth of filler, and the compacting machinary that adopts of construction and compacting functions etc., all will produce influence in various degree to the degree of compaction of filling layer.If slag filler grating good the suggestion grading limit of table 1 slag (as meet) and be in optimum moisture content, then slag is easy to compacting.The maximum dry density scope of slag is 2.3g/cm
3~2.6g/cm
3, the optimum moisture content scope is 6.0%~9.0%.
D, slag embankment cross-sectional design
Designs such as slag embankment cross-sectional design mainly comprises side slope of embankment ratio of slope, depth of fill, fills bed thickness, closedtop layer, underseal layer, interlayer, bank protection, drainage system and cross section.
(1) depth of fill and side slope ratio of slope
Fig. 1 is a slag embankment standard cross-section schematic diagram, its instructions for use be natural ground soil allowable bearing [σ] greater than 192kPa, natural ground neither soft foundation neither expansive soil foundation.Natural ground is handled through necessary leveling, filled slag roadbed 2 on the roadbed 1 after leveling is handled.If allowable bearing do not reach requirement, then should adopt change fill out, treatment measures such as powder spray piling reinforcing.The height of embankment generally is not more than 5m, and railway embankment using ratio of slope 11 is 1:1.5.The side slope ratio of slope 10 of immerseable embankment below design water level is 1: 1.75.
(2) fill bed thickness
The layer thickness control of filling of slag is important measures that guarantee the filling roadbed quality of slag.To heavy compacting machinary, the layering loose laying depth is 30cm, and should adjust according to test section compacting testing result.Also bed thickness can be reduced, to guarantee compaction quality.Ram vibration at small-sized electric and tamp under 3 times the situation, the degree of compaction the when compacted depth of slag is 15cm can reach about 85%.
(3) closedtop layer, underseal layer, interlayer
25~35cm cm is provided with the soil property layer 7 that binds below road surface structare layer, adopts road surface base layer materials such as rendzinas, two-ash soil or three dirt to make to bind layer.The every increase of slag depth of fill 2m should be provided with the thick cohesive soil interlayer 5 of 55~65cm together.When natural ground is an expansive soil foundation, then should adopt expansive soil foundation slag embankment cross-sectional design figure, see Fig. 2.After natural ground handled through necessary reinforcing, leveling, should adopt index of plasticity to be not less than 6 cohesive soil, bottom the slag embankment, the thick back cover layer 8 of 45~55cm is set, should overlay geo-grid on the local inhomogeneous ground.When natural ground is a soft foundation, then should adopt soft foundation slag embankment cross-sectional design figure, see Fig. 3.On excavating weak soil and changing roadbed 9 after filling out leveling, fill slag roadbed 2 again.
When the slag depth of fill surpasses 4m, should the thick interlayer 5 of 55~65cm together be set at the embankment middle part, interlayer adopts cohesive soil to fill.The every increase of slag embankment 2m then is provided with cohesive soil interlayer 7 one.Interlayer not only can stop the upper strata rainwater infiltration, can also absorb the swelling stress of slag embankment, reduces or avoids slag to expand to the destruction of embankment.Require not contain foreign material in the clay, compacting under optimum moisture content, loose laying depth and degree of compaction will reach the requirement of relevant road quality classification standard.
(4) bank protection
The side slope of embankment and curb are taked the 6 edge protection measures of soil property bank protection.Bank protection earth material employing index of plasticity is not less than 6 clay soil.The width of soil property bank protection 6 is no less than 2m for the roadbed both sides, and the gradient is identical with the slag embankment gradient.Weeper drain 4 is set in the soil property bank protection.The french drain cross dimensions is 40cm * 50cm, level interval 10~15m, and vertical interval 1.0~1.5m is quincunx arranged crosswise, the flare gradient 10%.When there is the water logging bubble embankment both sides, should adopt barricade and mortar bank protection, stop water to permeate to the slag embankment.When the anhydrous immersion in embankment both sides, can adopt the grid bank protection, turfing on the slope, engineering protection combines with biological protection.
The compaction in layers of soil property bank protection will be constructed simultaneously with embankment, large-scale compacting machinary roll less than the place, tamp with small-sized machine.
When filled-up ground is subjected to terrain and its features restriction or subgrade stability deficiency, can adopt the spats roadbed.The spats height should not surpass 4m, and the embankment spats that flooded by water logging should protect or reinforce.
(5) drainage system
Construction period, answer drainage trenching, in roadbed inside weeper drain 4 to be set.When construction rolls, horizontal wall inscription should be set, be beneficial to rainwater and be discharged to the embankment both sides; During embankment fills horizontal wall inscription and longitudinal gradient will be set, the horizontal wall inscription gradient is controlled at 1.5%~5.0%, and the longitudinal gradient gradient is controlled at 0.3%~3.0%.
Trapezoidal gutter is established in the embankment both sides, wide 180cm suitable for reading, the wide 60cm of end opening; The excavation highway section is established rectangle and is added a cover the edges of boards ditch, and landform is smooth, longitudinal gradient is mild lowly fills out, dish-like ditch is established in the shallow cut highway section; Trapezoidal catchwater is established in the big highway section of catchment area outside top, cutting slope.The road surface hydromining enters gutter or gutter with the mode of cross flow, water is concentrated to enter in the natural irrigation canals and ditches again.Gutter adopts M7.5 cemented rock 3 to build by laying bricks or stones, and cemented rock thickness is 250cm.The position of carrying out import and export is selected and is handled, phenomenon such as prevent obstruction, overflow, seepage, deposit, wash away and freeze.Gutter bottom of trench longitudinal gradient should be consistent with gradient incline, and be not less than 0.3%.The current of surface drainage ditch tube drainage can be discharged into the sedimentation basin post precipitation earlier and be discharged to outside the roadbed.
Catchwater should be provided with according to orographic condition and catchment area etc.The moat top catchwater of excavation roadbed should be arranged on beyond the groove 5m, and should lay in conjunction with landform.The embankment catchwater of filled-up ground upside should be not less than 2m apart from the distance of fill toe.In the area of heavy rainfull, look actual conditions and can establish one or multi-channel catchwater.The catchwater form of fracture should determine that the bottom of trench longitudinal gradient is not less than 0.3% in conjunction with position, displacement, landform and side slope situation are set.