CN105088911A - Novel runway foundation structure preventing and treating disasters caused by 'pot cover effect' - Google Patents

Abstract

This application discloses a new type of roadbed structure for preventing disasters caused by the "pot cover effect", which includes laying on the notoginseng ash soil layer close to and below the dew point depth; Blind ditch on both sides of the gravel layer. Among them: the notoginseng ash layer includes a first inclined part and a second inclined part, the notoginseng ash layer is axisymmetric with respect to the boundary line between the first inclined part and the second inclined part, and the slope of the first inclined part is between 1% and 5%. According to the scheme of this application, while ensuring the strength of the roadbed, it can prevent the upward migration of gaseous water in the deep roadbed soil and prevent the condensation of gaseous water under the partition layer to form secondary disasters; The purpose of preventing disasters caused by the "pot lid effect".

Description

A new roadbed structure to prevent disasters caused by "pot cover effect"

technical field

The patent of the invention relates to a new type of roadbed structure for preventing and controlling disasters caused by the "pot cover effect", which is suitable for preventing roadbed disasters of airport runways and road and railway roadbed disasters in similar situations.

Background technique

The "pot cover effect" in the roadbed of the airport runway refers to the phenomenon that the water content of the shallow soil of the roadbed increases due to the airtightness of the road surface, which prevents the water from the upper part of the roadbed from being discharged. The groundwater level in arid areas is low, and the capillary action of groundwater has a limited range of upward water transport, which can hardly directly supplement the soil moisture in the upper part of the road foundation. The moisture in the shallow soil generally comes from the condensation of gaseous water transported to the upper part by temperature difference in the shallow low temperature area. . This phenomenon of gaseous water migration and condensation in the upper part is particularly prominent in arid and cold regions, and it is an important source of moisture in the foundation soil of airport runways. The existence of the "pot cover effect" prevents the accumulated water from flowing out, resulting in a continuous increase in the water content of the road foundation soil, which can seriously cause serious engineering disasters such as a decrease in the strength of the road foundation soil, uneven subsidence, frost heave, and road foundation muddying.

The disaster caused by the "pot cover effect" is similar to that of subgrade muddying.

At present, there are mainly the following methods for the prevention and control of subgrade muddying:

First, increase the height of the subgrade according to the actual situation to keep the upper soil layer away from the ground or surface water; strengthen the pavement or replace the soil (such as silt) that is prone to muddying within a certain depth below the pavement with good soil (such as gravel); Slag, broken bricks, compressed peat, pine and cypress bark, etc. are used as insulation layers to prevent the freezing line of the subgrade from moving deep and thin the frozen layer.

Second, set up horizontal blind ditches, and set up horizontal blind ditches under the road grooves for muddying road sections with a longitudinal slope of less than 3% to timely discharge the longitudinal water flow in the permeable base and the excess water when the soil foundation thaws during the spring thawing period.

Third, to set up seepage ditches, piped seepage ditches can be used to lower the groundwater level near the roadbed or intercepted seepage ditches can be used to intercept and remove the interlayer water flowing to the roadbed; improve the pavement structure and lay gravel cushions, or lime soil and cinder lime soil cushions.

Fourth, use gravel and crushed stone with uniform particles as the temperature-conducting layer for ventilation.

Fifth, use geosynthetics to control road muddying, improve the use of roads, set up slurry-resistant roadbed structures to control road muddying, and surround roadbeds with polyvinyl chloride membranes.

However, the above-mentioned control methods can only solve the disasters caused by the increase of water content at the bottom of the pavement caused by capillary water transport, and are not suitable for disasters such as frost heave caused by the increase of water content caused by the condensation of upward moving gaseous water. Therefore, the above method is not applicable to the prevention and control of disasters caused by the "pot lid effect" under the condition of low groundwater level in arid and semi-arid areas.

Contents of the invention

In order to prevent disasters such as frost heave, muddying, and uneven subsidence of the airport runway caused by the "pot cover effect", and ensure its normal operation, the purpose of the present invention is to provide a new roadbed structure that prevents disasters caused by the "pot cover effect".

According to one aspect of the present application, a roadbed structure includes: a notoginseng ash layer laid close to and below the dew point; a gravel layer laid on the upper surface of the notoginseng ash layer; and blinds arranged on both sides of the gravel layer. Ditch; wherein: the notoginseng lime soil layer includes a first slope and a second slope, the Sanqi lime soil layer is axisymmetric with respect to the boundary line between the first slope and the second slope, and the slope of the first slope is between 1 %～5%.

The roadbed structure includes laying a layer of dense notoginseng ash soil layer near the dew point position to ensure the strength while mainly preventing the gaseous water in the deep roadbed soil from migrating upwards and preventing the condensation of gaseous water under the layer to accumulate water; and A slope gravel layer with large pores is laid on the upper part of the notoginseng ash soil layer to dredge the accumulated water in the upper part of the subgrade, and the drainage and air blocking can prevent disasters caused by the "pot cover effect".

Description of drawings

Other characteristics, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

Fig. 1 shows a road foundation structure for preventing disasters caused by the "pan lid effect" according to an embodiment of the present application.

Detailed ways

The application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain related inventions, rather than to limit the invention. It should also be noted that, for ease of description, only parts related to the invention are shown in the drawings.

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and embodiments.

Fig. 1 shows a road foundation structure for preventing disasters caused by the "pan lid effect" according to an embodiment of the present application.

As shown in Figure 1, the roadbed structure of the present invention includes a notoginseng ash layer 10 laid close to and below the dew point depth, a gravel layer 20 laid on the upper surface of the notoginseng ash layer, and blinds arranged on both sides of the gravel layer 20. Ditch 30. Here, the dew point depth is the depth corresponding to the dew point temperature.

Wherein, the notoginseng ash layer 10 includes a first inclined portion 11 and a second inclined portion 12 . The notoginseng ash layer is axisymmetric with respect to the boundary line between the first inclined portion 11 and the second inclined portion 12, and the slope of the first inclined portion is between 1% and 5%.

In some implementation manners, the distance d between the top of the notoginseng ash layer formed by the intersecting of the first inclined portion 11 and the second inclined portion 12 and the dew point depth 40 may be between 20 cm and 30 cm.

In some implementation manners, the thickness of the notoginseng ash layer 10 may be between 20 and 30 centimeters.

In some implementations, the thickness of the gravel layer 20 may be between 20-30 centimeters.

In the roadbed structure of the present invention, the laying of the notoginseng ash layer 10 can prevent the upward migration of deep gaseous water, and the laying of the notoginseng ash layer 10 below the dew point depth can prevent the generation of gaseous water condensation under the layer to form new disasters.

In some implementations, determining the dew point depth may include: determining the vapor pressure based on the thermostat ground temperature and relative humidity; determining the dew point temperature based on the vapor pressure; and determining the dew point depth based on the ground temperature-depth distribution curve.

In some application scenarios of these implementations, for example, the saturated vapor pressure at this temperature can be obtained by using the following formula (1) based on the ground temperature of the constant temperature layer of the soil obtained through perennial monitoring:

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; v</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; a</span>}\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 0.611</span>}\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 17.27</span>}\frac{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 273.2</span>}}{\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 36</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

Among them, _uv,sat is the saturated vapor pressure, and T is the temperature of the constant layer.

Then, according to the relative humidity of the soil pore air at the temperature of the constant temperature layer measured and the saturated vapor pressure obtained by the formula (1), the vapor pressure is obtained by using the following formula (2):

u _v =RH u _v,sat (2)

Among them, RH is the relative humidity, and _uv is the vapor pressure.

When measuring the relative humidity of the soil pore air at the temperature of the constant temperature layer, for example, a thermocouple dry hygrometer, a chilled mirror hygrometer, a polymer resistance/capacitance sensor and other equipment can be used for sampling measurement.

Next, bring the vapor pressure u _v calculated in formula (2) into the following formula (3) to obtain the dew point temperature:

${\mathrm{<span\; class="notranslate">\; T</span>}}_{\mathrm{<span\; class="notranslate">\; d</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 36</span>}\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 4700</span>}}{\mathrm{<span\; class="notranslate">\; I</span>}\mathrm{<span\; class="notranslate">\; no</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; v</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 16.78</span>}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

where T _d is the calculated dew point temperature.

Finally, based on the ground temperature-depth distribution curve obtained from perennial monitoring, the dew point depth can be determined.

The road foundation structure of the present invention fundamentally prevents gaseous water from migrating upwards by using the air barrier effect of the dense Panax notoginseng ash layer; the air barrier at the dew point can prevent condensed water from being produced under the gas barrier layer, preventing secondary disasters in the third It is formed at the bottom of the seven ash soil layer; the slope gravel layer can be used to discharge the possible accumulated water in the upper road foundation of the notoginseng ash layer in time to prevent the accumulation of seepage water from the surface.

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above-mentioned technical features, but should also cover the technical solution formed by the above-mentioned technical features without departing from the inventive concept. Other technical solutions formed by any combination of or equivalent features thereof. For example, a technical solution formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to).

Claims (4)

1. a road based structures, is characterized in that, comprising:

Be layed in close to and lower than the 37 lime earth layer of the dew point degree of depth;

Be layed in the sandy gravel stratum of described 37 lime earth layer upper surface; And be arranged at the french drain of described sandy gravel stratum both sides;

Wherein:

Described 37 lime earth layer comprises the first rake and the second rake, described 37 lime earth layer about the first rake and described second rake boundary line axisymmetricly, and the gradient of described first rake is between 1% ~ 5%.

2. road according to claim 1 based structures, is characterized in that:

The top of described 37 lime earth layer and the spacing of the described dew point degree of depth are 20 ~ 30 centimetres.

3. road according to claim 1 and 2 based structures, is characterized in that:

The thickness of described 37 lime earth layer is 20 ~ 30 centimetres.

4. road according to claim 3 based structures, is characterized in that:

The thickness of described sandy gravel stratum is 20 ~ 30 centimetres.