CN104573227B - A kind of modeling method considering the cement concrete pavement moisture field of health effect - Google Patents

Abstract

Consider a modeling method for the cement concrete pavement moisture field of health effect, comprising: 1) utilize Fick second law to set up the governing equation of water translocation, the function expression of this governing equation is: 2) to the governing equation determination definite condition of water translocation; 3) the dry test figure of concrete under health-preserving condition and SPSA algorithm is utilized to demarcate parameter involved in the governing equation of water translocation; 4) numerical solution of user-defined format and definite condition is utilized to solve with the governing equation of parameter to water translocation demarcated; Its solution is moisture distribution curve, namely considers the cement concrete pavement moisture field of health effect.Instant invention overcomes cement concrete pavement stress analysis in prior art and do not consider the deficiency of the effect of moist gradient, propose the modeling method that a kind of Exact Design for highway and urban road cement concrete pavement provides the cement concrete pavement moisture field of the consideration health effect of parameter.

Description

A kind of modeling method considering the cement concrete pavement moisture field of health effect

Technical field

The invention belongs to highway and urban road cement concrete pavement technical field, relate to a kind of modeling method that can be used for the cement concrete pavement moisture field of the consideration health effect of highway and urban road Cement Concrete Pavement Design.

Background technology

In cement concrete pavement structure analysis theories and method for designing, the stress analysis of road deck and calculating are a very important basic research job.

Because cement concrete pavement bears action of traffic loading, load stress is the chief component of road deck stress.Cement Concrete Pavement Slab, except bearing load stress, because it is chronically exposed in physical environment, also bears the warping stress caused by environment.The mechanism that warping stress produces is: when the upper surface temperature of Cement Concrete Pavement Slab or humidity are lower than the temperature of (or higher than) lower surface or humidity, due to the mechanism of expanding with heat and contract with cold of concrete material, the buckling deformation that Cement Concrete Pavement Slab can produce upwards (or downward), under the frictional resistance effect of Cement Concrete Pavement Slab and basic unit, the distortion of Cement Concrete Pavement Slab is obstructed, and then can produce warping stress and distortion.The warpage of Cement Concrete Pavement Slab can cause producing between plate and ground coming to nothing.Under Vehicle Load, in Cement Concrete Pavement Slab, upper surface (or lower surface) place generation tension is concentrated, and finally can cause the transverse breakage of plate, affects the usability of Cement Concrete Pavement Slab, shortens the pavement structure life-span.In China, the road deck fracture that this warpage causes is comparatively general, and under local function, namely Cement Concrete Pavement Slab produces fracture in build after complete 3 years to 5 years usually, and disconnected plate rate linearly ascendant trend in time, corresponding maintenance and reconstruction cause heavy congestion and economic loss.Therefore, study warpage destroy and corresponding influence factor significant to Exact Design cement concrete pavement.

According to the difference of the origin cause of formation, warpage can divide for the temperature warping caused by thermograde and the humidity warpage caused by moist gradient.All the time, the research of people to concrete flag temperature warping is more and be familiar with comparatively unification, defines system, complete temperature field is estimated, buckling deformation and calculation method for stress, and has applied it in design reality.For humidity warpage, although researchist has recognized that its satisfy the need distortion of panel and stress has considerable influence, but it is less to the research of the formation mechenism of cement concrete pavement moist gradient, main cause is that the influence factor of Cement Concrete Pavement Slab humidity and boundary condition are more, as free water, subbase or subgrade moisture content etc. in the relative humidity of road surface surrounding environment, rainfall, concrete.Meanwhile, the development of humidity warpage is relative complex, because concrete shrinkage not only depends on relative humidity and the gradient thereof of Cement Concrete Pavement Slab, and is subject to the impact in the concrete length of time.The Time Dependent characteristic of this concrete deformation need take in the computation process of warping stress, because the pace of change of relative humidity is slower than temperature variation.At present, had some cement concrete humidity to divide other modeling method abroad, but these methods all do not consider the feature of highway and urban road cement concrete pavement, namely do not consider early stage health effect.Therefore, there is no the mathematical model of the description cement concrete pavement structure water translocation of a set of applicable design both at home and abroad at present, cannot the moisture field of Accurate Prediction road deck, and then the humidity warpage of road deck and corresponding stress cannot be calculated.Therefore, all do not consider the effect of moist gradient in current Design Procedure for Cement Concrete Pavement both domestic and external and analysis theories, thus have ignored moist gradient completely and to satisfy the need the impact of panel deformation and stress.Above-mentioned present situation may cause underestimating the warpage that produces actual in cement concrete pavement and stress, and Pavement Design parameter and actual military service situation are not inconsistent.

Summary of the invention

The object of the invention is to overcome cement concrete pavement stress analysis in prior art and do not consider the deficiency of the effect of moist gradient, and then propose the modeling method that a kind of Exact Design for highway and urban road cement concrete pavement provides the cement concrete pavement moisture field of the consideration health effect of parameter.

For achieving the above object, the present invention adopts following technical scheme:

Consider a modeling method for the cement concrete pavement moisture field of health effect, it is characterized in that: the modeling method of the cement concrete pavement moisture field of described consideration health effect comprises the following steps:

1) utilize Fick second law to set up the governing equation of water translocation, the function expression of the governing equation of described water translocation is:

$\frac{\∂(\mathrm{\θ}-{\mathrm{\θ}}_L)}{\∂t}=\frac{\∂}{\∂x}\left\{D\frac{\∂}{\∂x}(\mathrm{\θ}-{\mathrm{\θ}}_L)\right\}$

Wherein:

θ is the inside concrete relative humidity simultaneously caused by the outside drying of moisture and self-desiccation, 0≤θ≤1;

θ _lthe inside concrete humidity reducing amount because self-desiccation causes, 0≤θ _l≤ 1;

X is the degree of depth apart from concrete slab surface, and unit is m;

T is the time, and unit is s;

The coefficient of diffusion of concrete moisture when D is outside drying, be the nonlinear function of concrete relative humidity, its function expression is:

$D\left(\mathrm{\θ}\right)=D_0(1-\exp (-{\left(\frac{{\mathrm{\α}}_0}{\mathrm{\θ}}\right)}^n\left)\right)$

Wherein:

D ₀be under drying regime be the coefficient of diffusion under the complete state of saturation of concrete, unit is m ²/ s;

α ₀be undetermined coefficient, relevant with concrete property, described concrete property includes but not limited to cement type, match ratio and porosity;

N is the coefficient describing coefficient of diffusion shape;

2) to step 1) the governing equation determination definite condition of water translocation set up, described definite condition comprises upper boundary conditions, downstream condition and the starting condition of considering health effect;

3) the dry test figure of concrete under health-preserving condition and SPSA algorithm is utilized to step 1) involved parameter is demarcated in the governing equation of water translocation set up; Test figure obtains by doing concrete drying test;

4) utilize the numerical solution of user-defined format and step 2) in definite condition and step 3) in the parameter of demarcating to step 1) governing equation of water translocation set up solves; The solution of the governing equation of described water translocation is moisture distribution curve, namely considers the cement concrete pavement moisture field of health effect.

As preferably, step 2 of the present invention) in the function expression of starting condition in definite condition be:

θ(x,t)＝100％,t＝0

The function expression of the upper boundary conditions in described definite condition is:

$\mathrm{\&theta;}(x,t)=\{\begin{array}{c}{f}_c{\mathrm{\&theta;}}_{en},if{f}_c{\mathrm{\&theta;}}_{en}<1,x=0,t>0\\ 1,if{f}_c{\mathrm{\&theta;}}_{en}\&GreaterEqual;1,x=0,t>0\end{array},$

Wherein:

θ _enit is ambient humidity;

F _cthe health factor to be calibrated, when air health-preservation, f _c=1; When being its health-preserving condition, fc be greater than 1 number;

Lower boundary in described definite condition adopts Neumann boundary condition:

$\frac{\&part;\mathrm{\&theta;}}{\&part;x}=0,x=l,t>0$

Wherein:

L is the degree of depth apart from concrete slab surface in solved governing equation.

As preferably, step 3 of the present invention) in fitness function in SPSA algorithm be:

$RMSE=\sqrt{\frac{\underset{w=1}{\overset{a}{\&Sigma;}}\underset{k=1}{\overset{b}{\&Sigma;}}{({\mathrm{\&theta;}}_{k,w}^{nea}-{\mathrm{\&theta;}}_{k,w}^{sim})}^2}{ab}}$

Wherein:

that w sensing station tests the concrete humidity obtained when Time labeling k; Inside the test that described sensor does when being and doing coefficient of diffusion parameter calibration, sensor, inside concrete, is specifically shown in embodiment;

it is the concrete humidity that w sensing station calculates when Time labeling k; This calculating is theoretical value, solves obtain according to the governing equation proposed above;

W is humidity sensor location label;

K is label drying time, k=1 ... the unit of 28, k is sky;

A is humidity sensor number;

B is drying test continuous days.

As preferably, step 4 of the present invention) in solve and comprise the solving of intermediate node, solving of top layer node and solving of bottom layer node;

The numerical expression form solved of described intermediate node is:

$\begin{array}{c}{\mathrm{\&theta;}}_{i,j+\mathrm{\&Delta;}t}=\frac{1}{1+0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\&lsqb;D\left({\mathrm{\&theta;}}_{i+1,j}\right)+2D\left({\mathrm{\&theta;}}_{i,j}\right)+D\left({\mathrm{\&theta;}}_{i-1,j}\right)\&rsqb;}\&times;\\ \&lsqb;0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\left(D\right({\mathrm{\&theta;}}_{i+1,j})+D({\mathrm{\&theta;}}_{i,j}\left)\right){\mathrm{\&theta;}}_{i+1,j}+{\mathrm{\&theta;}}_{i,j}+0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\left(D\right({\mathrm{\&theta;}}_{i-1,j})+D({\mathrm{\&theta;}}_{i,j}\left)\right){\mathrm{\&theta;}}_{i-1,j}\&rsqb;\end{array}$

Wherein:

θ _i,jfor the humidity of i-th node during jth time step, Δ x is spatial mesh size, and Δ t is time step.

Because the humidity of top layer node is the product of air humidity and the health factor, therefore, time dependent air humidity function is adopted for solving of top layer node; The numerical expression form solved of described top layer node is:

${\mathrm{\&theta;}}_{1,j}=\left\{\begin{array}{ccc}{f}_c{\mathrm{\&theta;}}_{en}\left(j\right),& if& f_c{\mathrm{\&theta;}}_{en}\left(j\right)<1\\ 1,& if& f_c{\mathrm{\&theta;}}_{en}\left(j\right)\&GreaterEqual;1\end{array}\right.,$

Because (N+1) individual node in the humidity of bottom layer node is that humidity value is equal with N number of node, therefore, the numerical expression form solved of bottom layer node is:

θ _N+1,j＝θ _N,j。

The present invention has the following advantages:

The invention provides a kind of modeling method considering the cement concrete pavement moisture field of health effect, the method comprises 1) utilize Fick second law to set up the governing equation of water translocation; 2) to the governing equation determination definite condition of water translocation; 3) parameter involved in the governing equation of water translocation is demarcated; 4) governing equation of the numerical solution of user-defined format to water translocation is utilized to solve; The solution of the governing equation of water translocation is moisture distribution curve, namely considers the cement concrete pavement moisture field of health effect.The concept introducing the health factor in governing equation of the present invention can describe the moisture diffusion regularity of early-age concrete boundary under health-preserving condition preferably, has clear and definite physical significance; Meanwhile, the numerical solution algorithm of foundation is explicit form, and computing velocity is high, and precision is high, is applicable to Project Realization.

Accompanying drawing explanation

Fig. 1 is the modeling method flow process of the cement concrete pavement moisture field of the worry health effect that the present invention proposes;

Fig. 2 is concrete moisture transfer mechanism test concept map (unit: cm);

Fig. 3 is pavement humidity field under the air health-preservation condition applying a kind of embodiment of the present invention;

Fig. 4 is pavement humidity field under the sealing compound health-preserving condition applying a kind of embodiment of the present invention;

Fig. 5 is pavement humidity field under the water health-preserving condition applying a kind of embodiment of the present invention;

Fig. 6 is the node schematic diagram in numerical solution.

Embodiment

See Fig. 1, the invention provides a kind of modeling method considering the cement concrete pavement moisture field of health effect, the modeling method of the cement concrete pavement moisture field of this consideration health effect comprises the following steps:

1) utilize Fick second law to set up the governing equation of water translocation, the function expression of the governing equation of water translocation is:

$\frac{\&part;(\mathrm{\&theta;}-{\mathrm{\&theta;}}_L)}{\&part;t}=\frac{\&part;}{\&part;x}\left\{D\frac{\&part;}{\&part;x}(\mathrm{\&theta;}-{\mathrm{\&theta;}}_L)\right\}$

Wherein:

θ is the inside concrete relative humidity simultaneously caused by the outside drying of moisture and self-desiccation, 0≤θ≤1;

θ _lthe inside concrete humidity reducing amount because self-desiccation causes, 0≤θ _l≤ 1;

X is the degree of depth apart from concrete slab surface, and unit is m;

T is the time, and unit is s;

The coefficient of diffusion of concrete moisture when D is outside drying, be the nonlinear function of concrete relative humidity, its function expression is:

$D\left(\mathrm{\&theta;}\right)=D_0(1-\exp (-{\left(\frac{{\mathrm{\&alpha;}}_0}{\mathrm{\&theta;}}\right)}^n\left)\right)$

Wherein:

D ₀be under drying regime be the coefficient of diffusion under the complete state of saturation of concrete, unit is m ²/ s;

α ₀be undetermined coefficient, relevant with concrete property, concrete property includes but not limited to cement type, match ratio and porosity;

N is the coefficient describing coefficient of diffusion shape;

2) to step 1) the governing equation determination definite condition of water translocation set up, definite condition comprises upper boundary conditions, downstream condition and the starting condition of considering health effect;

The function expression of the starting condition in definite condition is:

θ(x,t)＝100％,t＝0

The function expression of the upper boundary conditions in definite condition is:

$\mathrm{\&theta;}(x,t)\{\begin{array}{c}{f}_c{\mathrm{\&theta;}}_{en},if{f}_c{\mathrm{\&theta;}}_{en}<1,x=0,t>0\\ 1,if{f}_c{\mathrm{\&theta;}}_{en}\&GreaterEqual;1,x=0,t>0\end{array},$

Wherein:

θ _enit is ambient humidity;

F _cthe health factor to be calibrated, when air health-preservation, f _c=1; When being its health-preserving condition, fc be greater than 1 number;

Lower boundary in definite condition adopts Neumann boundary condition:

$\frac{\&part;\mathrm{\&theta;}}{\&part;x}=0,x=l,t>0$

Wherein:

L is the degree of depth apart from concrete slab surface in solved governing equation.

3) the dry test figure of concrete under health-preserving condition and SPSA algorithm is utilized to step 1) involved parameter is demarcated in the governing equation of water translocation set up; Test figure obtains by doing concrete drying test;

Fitness function in SPSA algorithm is:

$RMSE=\sqrt{\frac{\underset{w=1}{\overset{a}{\&Sigma;}}\underset{k=1}{\overset{b}{\&Sigma;}}{({\mathrm{\&theta;}}_{k,w}^{nea}-{\mathrm{\&theta;}}_{k,w}^{\mathrm{si}m})}^2}{ab}}$

Wherein:

that w sensing station tests the concrete humidity obtained when Time labeling k; Inside the test that sensor does when being and doing coefficient of diffusion parameter calibration, sensor, inside concrete, is specifically shown in embodiment;

it is the concrete humidity that w sensing station calculates when Time labeling k; This calculating is theoretical value, solves obtain according to the governing equation proposed above;

W is humidity sensor location label;

K is label drying time, k=1 ... the unit of 28, k is sky;

A is humidity sensor number;

B is drying test continuous days.

4) utilize the numerical solution of user-defined format and step 2) in definite condition and step 3) in the parameter of demarcating to step 1) governing equation of water translocation set up solves; The solution of the governing equation of water translocation is moisture distribution curve, namely considers the cement concrete pavement moisture field of health effect;

Wherein: solve and comprise the solving of intermediate node, solving of top layer node and solving of bottom layer node, see Fig. 6;

The numerical expression form solved of intermediate node is:

$\begin{array}{c}{\mathrm{\&theta;}}_{i,j+\mathrm{\&Delta;}t}=\frac{1}{1+0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\&lsqb;D\left({\mathrm{\&theta;}}_{i+1,j}\right)+2D\left({\mathrm{\&theta;}}_{i,j}\right)+D\left({\mathrm{\&theta;}}_{i-1,j}\right)\&rsqb;}\&times;\\ \&lsqb;0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\left(D\right({\mathrm{\&theta;}}_{i+1,j})+D({\mathrm{\&theta;}}_{i,j}\left)\right){\mathrm{\&theta;}}_{i+1,j}+{\mathrm{\&theta;}}_{i,j}+0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\left(D\right({\mathrm{\&theta;}}_{i-1,j})+D({\mathrm{\&theta;}}_{i,j}\left)\right){\mathrm{\&theta;}}_{i-1,j}\&rsqb;\end{array}$

Wherein:

θ _i,jfor the humidity of i-th node during jth time step, Δ x is spatial mesh size, and Δ t is time step.

Because the humidity of top layer node is the product of air humidity and the health factor, therefore, time dependent air humidity function is adopted for solving of top layer node; The numerical expression form solved of top layer node is:

${\mathrm{\&theta;}}_{1,j}=\left\{\begin{array}{c}{f}_c{\mathrm{\&theta;}}_{en}\left(j\right),if{f}_c{\mathrm{\&theta;}}_{en}\left(j\right)<1\\ 1,if{f}_c{\mathrm{\&theta;}}_{en}\left(j\right)\&GreaterEqual;1\end{array}\right.,$

Because (N+1) individual node in the humidity of bottom layer node is that humidity value is equal with N number of node, therefore, the numerical expression form solved of bottom layer node is:

θ _N+1,j＝θ _N,j。

Below to adopt method of the present invention to set up match ratio for certain cement concrete pavement under 3 kinds of Curing Methods, technical scheme provided by the present invention is further detailed.

1, described content sets up governing equation and definite condition corresponding with it to specifications

$\left\{\begin{array}{c}\frac{\&part;(\mathrm{\&theta;}-{\mathrm{\&theta;}}_L)}{\&part;t}=\frac{\&part;}{\&part;x}\left\{D\frac{\&part;}{\&part;x}(\mathrm{\&theta;}-{\mathrm{\&theta;}}_L)\right\},0<x<l,t>0\\ \mathrm{\&theta;}(x,0)=1,0\&le;x\&le;l,\\ \frac{\&part;}{\&part;x}\mathrm{\&theta;}(l,t)=0,t\&GreaterEqual;0,\\ \mathrm{\&theta;}(x,t)=\{\begin{array}{c}{f}_c{\mathrm{\&theta;}}_{en},if{f}_c{\mathrm{\&theta;}}_{en}<1,x=0,t>0,\\ 1,if{f}_c{\mathrm{\&theta;}}_{en}\&GreaterEqual;1,x=0,t>0\end{array},t\&GreaterEqual;0\end{array}\right..$

2, the demarcation of parameter: specifically comprise the following steps:

The preparation of 2.1 materials

Select the road cement concrete compound of a kind of typical water gray scale, be designated as N30, its match ratio is in table 1.The cement that compound is selected is P.O.42.5 Portland cement, adds water reducer (consumption is 1%) and, does not add other admixtures outward.

Table 1 concrete mix (kg/m ³)

2.2 process of the test

Make the cube concrete sample of 3 150mm × 150mm × 150mm, the inside concrete humidity of test specimen under 3 kinds of Curing Methods such as air health-preservation, sealing compound health and watering health is tested, only tieing up direction at concrete 1 for simulation moisture (is x direction, namely vertical) upper migration, concrete sample other 5 surfaces except surface need be sealed, divide evaporation to prevent water.In addition, due to the self-desiccation characteristic of early-age concrete, need to carry out humidity measurement to complete sealing mixed material test specimen.

Adopt Switzerland SensirionSHT15 Temperature Humidity Sensor to carry out concrete humidity test, its humidity measurement precision is ± 2%.

Process of the test is as follows:

Pouring concrete: pour into a mould the concrete according to match ratio configuration in the concrete test die of reserved instrument connection;

Sensor is laid: after 4 hours, slowly extracted by embedding pvc pipe, in time sensor probe is inserted concrete, and by 2 side end aperture silica gel plugs and paraffin sealing, divides evaporate from the side to prevent water;

Sealing, health and test: according to different Curing Method requirement, surface of test piece is carried out epoxy sealing, air health-preservation, sealing compound health and watering health, wherein sealing compound health is that (consumption is 0.1m in disposable sprinkling ²/ Kg), watering health is that (consumption is 0.2m in timing watering every day ²/ Kg), start humidity measurement, humidity detection frequency is 1h simultaneously, and monitoring periods is 28d.During test, test specimen moisture releasing is indoor, in process of the test, test specimen desiccated surface upward, and continue with temperature state the air ambient that pectinid declines in time to form concrete surface humidity by the adjustable heat electric fan of temperature, wherein, moisture transfer mechanism test concept is shown in Fig. 2.

Data store and analyze: read by corresponding software by the humidity data of different test specimen, and stored in Microsoft Access database, for subsequent analysis is prepared.

The demarcation of 2.3 parameters

Adopt SPSA algorithm to carry out the parameter calibration of model, parameter that algorithm adopts (span of this parameter by literature survey obtain (1, zP, NajjarLJ.Nonlinearwaterdiffusioninnonsaturatedconcrete.M aterialandConstruction, 1972, Vol.5 (1): 3 ~ 20; 2, AkitaH, FujiwaraT, OzakaY.Apracticalprocedurefortheanalysisofmoisturetransf erwithinconcreteduetodrying.MagazineofConcreteResearch, 1997, Vol.49 (179): 129 ~ 137; 3, XuQ, RuizJM, ChangGK, etal.MoisturetransportmodelforenhancingFHWAHIPERPAVpredi ctions.TransportationResearchRecord:JournaloftheTranspor tationResearchBoard, 2009, Vol.2113 (1): 1 ~ 12; 4, WongSF, WeeTH, SwaddiwudhipongS, etal.Studyofwatermovementinconcrete.2001:53,205 ~ 220)) in table 2.In the fitness function of algorithm come from measured data, obtained by numerical solution.

Table 2SPSA algorithm parameter

Parameter	Value
		D 0(×10 -10m 2/s)	[0.1,8.0]
α 0	[0.01,0.1]
		n	[1,16]
f c	[1,3]

That demarcates the results are shown in Table 3.

Table 3 model parameter calibration result

3, model solve the determination with moisture field, adopt Matlab programme, solve governing equation, the moisture field at the different depth place under the 3 kinds of health-preserving conditions finally obtained is as Fig. 3, Fig. 4 and Fig. 5.As seen from the figure, concrete under 3 kinds of health-preserving conditions all reduces with the growth of drying time in the humidity at different depth place, but the size of changing down is relevant with Curing Method, the magnitude relationship of changing down is: the health of air health-preservation > sealing compound health > water.

Above-mentioned is can understand and apply the invention for the ease of those skilled in the art to the description of embodiment.Those of ordinary skill in the art can make amendment to this example, and principle described herein are applied in other embodiments and need not through creative work.Therefore, the invention is not restricted to embodiment here, those skilled in the art are according to announcement of the present invention, and the improvement made for the present invention and amendment should within protection scope of the present invention.

Claims (4)

1. consider a modeling method for the cement concrete pavement moisture field of health effect, it is characterized in that: the modeling method of the cement concrete pavement moisture field of described consideration health effect comprises the following steps:

1) utilize Fick second law to set up the governing equation of water translocation, the function expression of the governing equation of described water translocation is:

$\frac{\&part;(\mathrm{\&theta;}-{\mathrm{\&theta;}}_L)}{\&part;t}=\frac{\&part;}{\&part;x}\left\{D\frac{\&part;}{\&part;x}(\mathrm{\&theta;}-{\mathrm{\&theta;}}_L)\right\}$

Wherein:

θ is the inside concrete relative humidity simultaneously caused by the outside drying of moisture and self-desiccation, 0≤θ≤1;

θ _lthe inside concrete humidity reducing amount because self-desiccation causes, 0≤θ _l≤ 1;

X is the degree of depth apart from concrete slab surface, and unit is m;

T is the time, and unit is s;

The coefficient of diffusion of concrete moisture when D is outside drying, be the nonlinear function of concrete relative humidity, its function expression is:

$D\left(\mathrm{\&theta;}\right)=D_0(1-\exp (-{\left(\frac{{\mathrm{\&alpha;}}_0}{\mathrm{\&theta;}}\right)}^n\left)\right)$

Wherein:

D ₀be under drying regime be the coefficient of diffusion under the complete state of saturation of concrete, unit is m ²/ s;

α ₀be undetermined coefficient, relevant with concrete property, described concrete property includes but not limited to cement type, match ratio and porosity;

N is the coefficient describing coefficient of diffusion shape;

2) to step 1) the governing equation determination definite condition of water translocation set up, described definite condition comprises upper boundary conditions, downstream condition and the starting condition of considering health effect;

3) the dry test figure of concrete under health-preserving condition and SPSA algorithm is utilized to step 1) involved parameter is demarcated in the governing equation of water translocation set up;

4) utilize the numerical solution of user-defined format and step 2) in definite condition and step 3) in the parameter of demarcating to step 1) governing equation of water translocation set up solves; The solution of the governing equation of described water translocation is moisture distribution curve, namely considers the cement concrete pavement moisture field of health effect.

2. the modeling method of the cement concrete pavement moisture field of consideration health effect according to claim 1, is characterized in that: described step 2) in the function expression of starting condition in definite condition be:

θ(x,t)＝100％,t＝0

The function expression of the upper boundary conditions in described definite condition is:

$\mathrm{\&theta;}(x,t)=\left\{\begin{array}{c}{f}_c{\mathrm{\&theta;}}_{en},if{f}_c{\mathrm{\&theta;}}_{en}<1,x=0,t>0,\\ 1,if{f}_c{\mathrm{\&theta;}}_{en}\&GreaterEqual;1,x=0,t>0\end{array}\right.$

Wherein:

θ _enit is ambient humidity;

F _cthe health factor to be calibrated, when air health-preservation, f _c=1; When being its health-preserving condition, fc be greater than 1 real number;

Lower boundary in described definite condition adopts Neumann boundary condition:

$\frac{\&part;\mathrm{\&theta;}}{\&part;x}=0,x=l,t>0$

Wherein:

L is the degree of depth apart from concrete slab surface in solved governing equation, unit m.

3. the modeling method of the cement concrete pavement moisture field of consideration health effect according to claim 2, is characterized in that: described step 3) in fitness function in SPSA algorithm be:

$RMSE=\sqrt{\frac{\underset{w=1}{\overset{a}{\&Sigma;}}\underset{k=1}{\overset{b}{\&Sigma;}}{({\mathrm{\&theta;}}_{k,w}^{mea}-{\mathrm{\&theta;}}_{k,w}^{sim})}^2}{ab}}$

Wherein:

that w sensing station tests the concrete humidity obtained when Time labeling k;

it is the concrete humidity that w sensing station calculates when Time labeling k;

W is humidity sensor location label;

K is label drying time, k=1 ... the unit of 28, k is sky;

A is humidity sensor number;

B is drying test continuous days.

4. the modeling method of the cement concrete pavement moisture field of consideration health effect according to claim 3, is characterized in that: described step 4) in solve and comprise the solving of intermediate node, solving of top layer node and solving of bottom layer node;

The numerical expression form solved of described intermediate node is:

$\begin{array}{c}{\mathrm{\&theta;}}_{i,j+\mathrm{\&Delta;}t}=\frac{1}{1+0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\&lsqb;D\left({\mathrm{\&theta;}}_{i+1,j}\right)+2D\left({\mathrm{\&theta;}}_{i,j}\right)+D\left({\mathrm{\&theta;}}_{i-1,j}\right)\&rsqb;}\&times;\\ \&lsqb;0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\left(D\left({\mathrm{\&theta;}}_{i+1,j}\right)+D\left({\mathrm{\&theta;}}_{i,j}\right)\right){\mathrm{\&theta;}}_{i+1,j}+{\mathrm{\&theta;}}_{i,j}+0.5\frac{\mathrm{\&Delta;}t}{{\left(\mathrm{\&Delta;}x\right)}^2}\left(D\left({\mathrm{\&theta;}}_{i-1,j}\right)+D\left({\mathrm{\&theta;}}_{i,j}\right)\right){\mathrm{\&theta;}}_{i-1,j}\&rsqb;\end{array}$

Wherein:

θ _i,jfor the humidity of i-th node during jth time step, Δ x is spatial mesh size, and Δ t is time step; The numeric format solved of described top layer node is:

${\mathrm{\&theta;}}_{1,j}=\left\{\begin{array}{ccc}{f}_c{\mathrm{\&theta;}}_{en}\left(j\right),& if& f_c{\mathrm{\&theta;}}_{en}\left(j\right)<1,\\ 1,& if& f_c{\mathrm{\&theta;}}_{en}\left(j\right)\&GreaterEqual;1\end{array}\right.$

The numeric format solved of described bottom layer node is:

θ _N+1,j＝θ _N,j。