CN1234942C - Composite temperature controlled ventilation roadbed - Google Patents

Abstract

The present invention relates to a mode for effectively protecting perennially frozen soil below road subgrades and building foundations and improving the stability of engineering construction in the construction of railways, roads and engineering construction carried out in a perennially frozen soil zone. The structure is characterized in that ventilation pipes are vertical to the running direction of a subgrade and buried in a position in embankment filling soil at a certain depth, a ventilating device which can control temperature automatically is arranged on the end part of each ventilation pipe, thermal insulation materials are arranged between a ventilating subgrade and the ventilation pipes or on the upper parts of the entire ventilation pipes, soil and stones are used for filling, covering and tamping. The earth body in the inner part of the subgrade is controlled to carry a heat quantity interchange only with outside low temperature airflows through the ventilating devices which can control temperature automatically; the thermal insulation materials arranged between the ventilation pipes or on the top part of the ventilaton pipe can preventing outside heat quantity from invading; the perennially frozen soil below is effectively protected, and the stability of the subgrade on the perennially frozen soil is kept at a high level; the influence of frost heave and thaw collapse caused by season active layer freeze-thaw cycles to the stability of the subgrade is effectively avoided. Natural cold energy is fully used in the novel subgrade, the stability of engineering construction in a perennially frozen soil zone is ensured, and the problem of constructing in a perennially frozen soil zone is solved.

Description

Compound temperature control ventilated embankment

Technical field

The present invention relates to carry out protecting road foundation and bottom, building foundation ever-frozen ground effectively in railway, highway and the engineering construction construction, improve a kind of pattern of engineering construction stability in Permafrost Area.

Background technology

Soil freeze and unique cold living phenomenon and natural landscape are moulded in the thawing effect, mankind's activity has participated in this effect energetically, has brought up the fragile ecological environment that cooperative development under this unique environment, this special cold environment is called as frozen soil environment.Because the thick-layer ground ice that frozen soil contained is in fragile thermal equilibrium state, thawing and frozen soil environment that the thick-layer ground ice is very easily brought out in the human engineering activity change, to the stability generation significant effects of engineering construction.Qinghai-Tibet Railway, Qinghai-Tibet Highway object of construction production and the Xinjiang-Tibet highway that will carry out that China builds, Xinjiang-Tibet railway, south water to north west lineman's journey all face high temperature (be temperature near 0 ℃ ever-frozen ground), hight-ice-content permafrost (being that the volume ice content surpasses 30% ever-frozen ground substantially), weather changes many difficult problems such as the continuous degeneration of warm ever-frozen ground.How to resolve the interaction of roadbed and basis and ever-frozen ground, guarantee that roadbed and basis are steady in a long-term, guarantee that the engineering construction safe operation also just becomes the key scientific problems that needs to be resolved hurrily.

The fragile cold conspicuous contradiction of distinguishing between the positive engineering activity of frozen soil, ecological environment and the mankind is perplexing carrying out smoothly of such regional engineering construction always.For this reason, the scientist of each frozen soil big country of the world is effective for seeking, engineering construction is convenient, and unremitting effort is being carried out in cost engineering measure low, free from environmental pollution always.Russian scientist J F Nixon (Geothermal aspects Of ventilated pad, design.Proceedings of the Third International conference On Permafrost.1978, Edmonton, Alberta Canada:841-846) has carried out managing the experimental study of wind refrigeration system all.Contain illuminate, Zhang Luxin, Yang Chengsong etc. in " application of insulation treatment measures in ever-frozen ground district highway construction " (dirt band, 2002,24 (5): reported 618-622) that the engineering measure of protecting ever-frozen ground is to overlay one deck heat insulating material in roadbed.The measure of the new-type protection ever-frozen ground of U.S.'s Alaska traffic science report is the top (see figure 7) that the combination of hair fastener heat pipe and heat insulating material is positioned over embankment.This measure main feature is to utilize heat pipe to start working when the heat insulating material temperature of lower is higher than upper temp, the bottom heat is delivered to top, temperature condition is next quits work opposite, stops the following biography of heat, and general effect plays the effect of " thermal diode " of one-way heat conduction.But because heat pipe is embedded in embankment inside, in case the working medium in the heat pipe leak, cause the forfeiture of heat pipe usefulness to repair.China scientific worker is based on national conditions; around Qinghai-Tibet Railway country Important Project project; with commonly used on permafrost region roadbed basis etc. before be the protection frozen soil principle of the passiveness of means to increase thermal resistance; change into " cooling roadbed " is the positive protection ever-frozen ground principle of means; utilize the feature of variation of ambient temperature; regulation and control embankment and extraneous heat transmission and exchange reach and strengthen the heat balance of ever-frozen ground ground temperature field, thereby provide reliable assurance to engineering works stable.The project of national nature science fund project of application; Chinese Academy of Sciences's " light in western part---protection frozen soil temperature control key technology research in the frozen soil engineering "; the major project of Chinese Academy of Sciences's knowledge innovation project " qinghai-tibet railway engineering and ever-frozen ground interact and environmental effect " has been carried out case study with regard to the problems referred to above emphatically, has finished the patent application (application number: 03114640.6,03114641.4) of " automatic temperature-controlled ventilation installation " and " the automatic temperature-controlled ventilation installation of fluid pressure type " under study for action.Open-air performance is seen Fig. 4, Fig. 5.

Summary of the invention

Purpose of the present invention is based on above-mentioned thinking and the case study of carrying out, aim to provide a kind of efficient compound temperature control roadbed, be about to have the air chimney of automatic temperature-adjusting control system and the combination of heat insulating material is laid in the roadbed, only carry out exchange heat with the low-temperature airflow in the external world by the inner soil body of auto temperature controlled system control roadbed; Be arranged between the air chimney or the heat insulating material on top can intercept external heat and invades, effectively preserve the cold energy of its underpart, can keep and strengthen the thermal balance of ever-frozen ground thus, or the stability of engineering construction is based upon on the higher level by the accumulation of cold energy and the continuous reduction of ground temperature field; Simultaneously, also can effectively avoid the influence of frost heave that the freeze thawing circulation of season activity brought, thaw collapse to subgrade stability.

Purpose of the present invention can be achieved through the following technical solutions

A kind of compound temperature control ventilated embankment, it is the position that air chimney, the heat insulating material that will have automatic temperature-controlled ventilation installation is embedded in the embankment filled soil certain depth, automatic temperature-controlled ventilation installation is installed in the end of air chimney, air chimney is perpendicular to road-trend, heat insulating material is arranged between the air chimney, or the top of whole air chimney.

So-called heat insulating material is meant a kind of in polystyrene (EPS), polyurethane (PU), foam glass, the injection moulding polystyrene (XPS).

Above-mentioned automatic temperature-controlled ventilation installation has two kinds of forms

1, memorial alloy formula thermostat

By to the combining of memory alloy spring (SMS) and common spring (GS), just can under the different temperatures ambient conditions, carry out different interactions; Promptly under high temperature AF temperature environment, the coefficient of elasticity of SMS is higher than the coefficient of elasticity of GS, and SMS can finish impetus to GS; And be lower than under the MF temperature environment, the coefficient of elasticity of SMS is lower than the coefficient of elasticity of GS, and GS can finish reverse impetus to SMS.AF, MF can finish setting by in conjunction with on-the-spot radiation condition, temperature condition and laboratory test in the process of processing and processing memory alloy spring.By being connected of complex spring and air door axostylus axostyle, can finishing under the condition of different temperatures the door opening or the action of closing, thereby reach the purpose of control temperature.

2, fluid pressure type thermostat

Utilize the variation of the water body induction outside air temperature in the temperature induction unit in the system.Be lower than in 0 ℃ at outside air temperature, the water body in the unit freezes, and produces 9% volume expansion.Water body in the unit produces pressure to hydraulic oil on every side behind freezing expansion, under the effect of hydraulic fluid pressure, promote the generation of hydraulic pressure plug and move, and the air door that promotion air-flow control module is opened in the air chimney carries out aeration-cooling; When outside air temperature was higher than 0 ℃, frozen ice body can melt in the temperature induction unit, and volume produces and shrinks simultaneously; piston is returned to the position before freezing under the effect of spring, and closes the air door in the air chimney; stop hot air to enter, play the effect of the inner cold energy of protection roadbed.

Fig. 6 has shown the actual measurement ground temperature data of automatic control temperature control ventilated embankment in section on Qinghai-Tibet Railway.A～d represents that respectively the automatic control embankment experiences whole 4 typical periods of summer of roadbed center ground temperature situation.Among a with dotted line illustrated embankment structure and the height, the position at air chimney place.Ordinate is for showing the degree of depth axle of starting at from the embankment top; Abscissa is the ground temperature value of temperature boring observation.As seen from the figure, the temperature curve slope of the above soil body of air chimney is totally basic identical, promptly under the constant substantially situation of soil body coefficient of thermal conductivity, exists a comparatively stable hot-fluid to transmit heat to the bottom soil body.By actual measurement soil body coefficient of thermal conductivity is 1.1W/ (mK) substantially, by the equation of heat conduction

$\mathrm{\Φ}=\mathrm{\λA}\frac{\mathrm{\Δt}}{\mathrm{\δ}},$ In the formula: the Phi unit time is transmitted to the heat on surface 2 from surface 1; The λ coefficient of thermal conductivity, W/ (mK); The A heat-conducting area; The difference of Δ t surface 1 and surperficial 2 temperature; δ thickness.Get stratum apart from embankment end face 1～2m, the end face temperature-averaging value in 6～September, the unit area hot-fluid, promptly heat flow density is:

$\frac{\mathrm{\&Phi;}}{A}=\mathrm{\&lambda;}\frac{\mathrm{\&Delta;t}}{\mathrm{\&delta;}}=1.1W/(m\&CenterDot;K)\&times;\frac{5.8-2.3}{1m}=3.85W/{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="C20041000213500091.png,C20041000213500111.png"\; state="\{\{state\}\}">m</figure-callout>}}^2$

Calculate for simplifying, the hydraulic pressure attemperating unit is partly used in automatic control, close air door at whole warm season (temperature is higher than 0 ℃), air chimney wherein coefficient of thermal conductivity of air after closing keeps 0.02W/ (mK), now calculate with the most frequently used EPS heat insulating material coefficient of thermal conductivity 0.03W/ (mK), lay the heat insulating material of 10cm between the air chimney, keep the temperature difference (complex chart 3 and heat insulating material are used field data) of 3 ℃ of heat insulating material upper and lower end faces, be about by the heat flow density of heat insulating material aspect:

$\frac{\mathrm{\&Phi;}}{A}=\mathrm{\&lambda;}\frac{\mathrm{\&Delta;t}}{\mathrm{\&delta;}}=0.03W/(m\&CenterDot;K)\&times;\frac{2-(-1)}{0.1m}=0.9W/{\mathrm{<figure-callout\; id="2"\; label="m"\; filenames="C20041000213500091.png,C20041000213500111.png"\; state="\{\{state\}\}">m</figure-callout>}}^2$

Because warm season enters the caloric requirement of the bottom soil body and eliminated by the heat release of cold season, unnecessary heat release is used for the reduction of soil body temperature.Can calculate thus, the heat flux that reduces by 1 times just can improve whole 2 times cooling effect.By calculating, by the heat flux of air chimney aspect in the ventilated embankment, heat flow density of the present invention is 23.4% of an automatic control ventilated embankment, and cooling effect of the present invention is 8.6 times of automatic temperature-controlled ventilated embankment.Comprehensive air chimney in off position down, the inner heat transfer free convection of the air chimney that the raying heat absorption of outer face, air chimney both sides causes, and because the heat conducting influence of the following embankment filled soil in heat insulating material interface under the thermal boundary condition of both sides, and the influence of other secondary cause such as air chimney tube wall conduction of heat, calculate with the comparatively conservative usefulness 40～50% of subduing, the cooling effect of this patent will be 3～4 times of automatic temperature-controlled ventilated embankment.

The beneficial effect of advantage of the present invention and generation is

1, is installed in the automatic temperature-controlled ventilation installation of air chimney end, have and allow flowing of relative low-temperature airflow, and the function that stops high temperature gas flow to flow, promptly when ambient air temperature is lower than 0 ℃, automatically open air door, carry out the convection heat transfer' heat-transfer by convection of the inner soil body and extraneous air-flow by air chimney; When environment temperature is higher than 0 ℃, close air door, stop air-flow and top soil body heat to import into, reach unidirectional refrigeration, thus the stability of protection roadbed bottom frozen soil.Through on-the-spot half a year of many practices, this covering device is finished compulsory exercise automatically in the design temperature scope, open or close air door, and action accurately, and is working properly;

2, between air chimney or whole top lay one deck heat insulating material.Cooling usefulness from whole roadbed bottom, automatic control ventilated embankment cooling usefulness improves a lot, stoped the direct heat effect of air-flow by day to embankment inside, but under embankment surface heat fringe conditions effect in summer, because the coefficient of thermal conductivity number of embankment filled soil improves relatively, still there is comparatively strong hot-fluid to conduct to the bottom ever-frozen ground by the soil body between the air chimney, its usefulness is produced a very large impact, the present invention is by between air chimney, or lay heat insulating material on the top of air chimney and just can greatly cut down this conduction of heat, realize that thermal discharge is far longer than caloric receptivity, improved whole cooling usefulness;

3, the present invention is with the combination of automatic temperature-controlled ventilated embankment and heat insulating material, make full use of both outstanding advantages, by employing to the nature cold energy, storage, reach maximum cooling-down effect to roadbed, solve the conspicuous contradiction between fragile cold district's frozen soil and the human engineering activity effectively, satisfy the specific (special) requirements of engineering construction at high temperature, hight-ice-content permafrost zone engineering stability;

4, aspect engineering stability, because the enforcement of the present invention in qinghai-tibet railway engineering, make the continuous accumulation of cold energy in the engineering construction basis, ever-frozen ground can be maintained in lower, the stable thermal field, effectively avoid the intensification phenomenon of ground temperature behind the common engineering construction, and the subgrade settlement that causes therefrom distortion, Foundation Design stability is based upon on the higher level.Simultaneously because the raising of the artificial ever-frozen ground upper limit, avoided the influence of frost heave that the freeze thawing circulation of seasonal active layer brought, thaw collapse to engineering stability;

5, the present invention is under the prerequisite of the thermal field stability requirement that satisfies roadbed bottom ever-frozen ground, can be by reducing the rational deployment of depth of fill and air chimney and heat insulating material, reduce the cost of system engineering, shorten the construction period, actual construction cost with reference to Qinghai-Tibet Railway construction, the engineering cost of this invention is about the 1/2-1/3 of jackstone roadbed, remain basically stable with the engineering measure expense of Qinghai-Tibet Highway hot pin test section, but cooling-down effect of the present invention obviously is better than the former.Therefore, from the input and output of whole engineering measure, the cost of compound temperature control roadbed will obviously be better than other engineering measure, the intensity height, and engineering stability is good;

6, aspect range of application, because storage cold-working mechanism except high ice content ever-frozen ground district, all can be used in the higher area of environment temperature technical measures of the present invention such as high temperature ever-frozen ground, island ever-frozen ground.

Description of drawings

Fig. 1 is compound temperature control ventilated embankment sectional schematic diagram

Fig. 2 is the automatic temperature-controlled ventilation installation of Fig. 1

Fig. 3 is that Fig. 1 heat insulating material is arranged on schematic diagram between the ventilated embankment air chimney

Fig. 4 be Fig. 1 early morning automatic temperature-controlled air door be in and open and schematic diagram just in off position

Fig. 5 be Fig. 1 noon automatic temperature-controlled air door be in and close group's state diagram

Fig. 6 is that not same date automatic control and nothing centre-drilling hole temperature between keyholed back plate are shown the contrast schematic diagram

Fig. 7 is the road structure of hair fastener type heat pipe and heat insulating material combination

The specific embodiment

Below, in conjunction with the accompanying drawings, will be further described again the present invention

Embodiment 1, and a kind of compound temperature control ventilated embankment is to be made up of automatic temperature-controlled ventilation installation 1 (Chinese invention patent has been applied in self-control, and application number is 03114640.6,03114641.4), cement air chimney 2, polystyrene (EPS) plate, native stone.Air chimney 2 is perpendicular to road-trend and be embedded in the bottom of embankment filled soil, and automatic temperature-controlled ventilation installation 1 is installed in its end, and polystyrene (EPS) plate is arranged on the top of ventilated embankment air chimney 2, covers compacting with native stone.

When outside air temperature was lower than 0 ℃, the air door 4 of automatic temperature-controlled ventilation installation 1 opened automatically, impelled the embankment and the basic internal soil body to carry out heat convection by air chimney 2 and cool ambient air; When outside air temperature was higher than 0 ℃, air door 4 auto-closings of automatic temperature-controlled ventilation installation 1 stoped importing into of external heat.

Lay one deck 10cm polystyrene (EPS) warming plate on air chimney top, overcome emitting of low-temperature heat quantity, cut down embankment filled soil greatly by the transmission of conduction of heat to the air chimney 2 bottom soil bodys and ever-frozen ground heat.

Combination by thermostat 1, air chimney 2 and polystyrene (EPS) warming plate, overcome emitting of low-temperature heat quantity, importing into of heat of high temperature, greatly improved the cooling usefulness of roadbed, employing, storage have been realized to cold energy, guaranteed the stability of ever-frozen ground, satisfied the technical need of Qinghai-Tibet Railway roadbed in ever-frozen ground stability.

Embodiment 2, and air chimney 2 is embedded in the position of embankment filled soil certain depth, and automatic temperature-controlled ventilation installation 1 is installed in its end, and injection moulding polystyrene (XPS) warming plate is laid between the air chimney, and its heat-insulating cooling effect is identical with embodiment 1.

Claims (2)

1. compound temperature control ventilated embankment, form by automatic temperature-controlled ventilation installation (1), air chimney (2), heat insulating material (3), native stone, it is characterized in that air chimney is perpendicular to road-trend and be embedded in the position of embankment filled soil certain depth, automatic temperature-controlled ventilation installation (1) is installed in its end, heat insulating material (3) is arranged between the ventilated embankment air chimney (2)/or the top of whole air chimney (2), cover compacting with native stone.

2. a kind of compound temperature control ventilated embankment according to claim 1 is characterized in that a kind of in the polystyrene (EPS), polyurethane (PU), foam glass, injection moulding polystyrene (XPS) of described heat insulating material (3).

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