CN103469710A - Roadbed quality control construction method based on rebound modulus - Google Patents

Abstract

The invention relates to the technical field of cohesive pavements paved on site in fixed buildings, and in particular relates to a roadbed quality control construction method based on rebound modulus. The roadbed quality control construction method comprises the following steps: a. determining a design deflection value ls of the road face; b. according to the fact that the calculation deflection value of the road face is smaller than the design deflection value of the road face, and through the calculation, obtaining a compressive rebound modulus value E0 of the top surface of a roadbed; c. obtaining the hierarchical control standard for the modulus of the roadbed through a modulus attenuation method according to the E0; and d. performing data treatment. Rebound modulus is an important mechanical parameter in the road system, and can be used for avoiding the unfavorable condition that the degree of compaction can not truly reflect the integral condition of the roadbed during the construction process. According to the invention, the roadbed quality is controlled by calculating and through directly controlling mechanical performance indexes of the roadbed; hierarchical control indexes are obtained on the basis of calculation, thus a rebound modulus control method for construction quality of the roadbed is more reasonable, meanwhile, with the adoption of the rebound modulus for controlling the roadbed quality, the contacting between roadbed and road surface departments during handing over and acceptance inspection of a project is closer.

Description

A kind of the quality control of foundation job practices based on the modulus of resilience

[technical field]

The present invention relates to the coherent paving technical field of on-the-spot making in fixed buildings, specifically a kind of the quality control of foundation job practices based on the modulus of resilience.

[background technology]

Traditional highway subgrade construction is all carried out roadbed design and quality control on construction with compaction degree method, such as being more than or equal to compaction requirement in 96%, 0.8～1.5m depth bounds, compaction requirement in 0～0.8m depth bounds below the soil subgrade end face is more than or equal to 94%.On the one hand, compaction degree method hierarchical control index is to sum up and obtain according to engineering experience, lacks theoretical calculating and supports.On the other hand, difference due to factors such as dam filling construction, the soil property of banketing and water content, the roadbed of identical degree of compaction, larger difference may appear in its mechanical property, this may cause two kinds of unfavorable project situation: 1) even degree of compaction meets code requirement, the integral rigidity of roadbed and intensity but can't guarantee the pavement performance requirement; 2) although degree of compaction does not also reach designing requirement, and the integral rigidity of roadbed and intensity have met the pavement performance requirement.Mainly, degree of compaction is the physical property index that characterizes road structure to its reason in essence, can not directly reflect the mechanical property of roadbed.Simultaneously, road surface department requires the modulus of resilience of roadbed to reach the designing requirement value when pavement design; And degree of compaction all be take as controlling index in roadbed design and work progress in roadbed department, thereby, when the engineering check, be difficult to realize good linking between two departments.

[summary of the invention]

The present invention is difficult to reach deficiency and the defects such as designing requirement in order to solve prior art Road matrix amount exactly, provide a kind of method novel, safe and reliable, can realize building and meeting the quality control job practices of the roadbed of designing requirement on the bases such as different soil properties, method.

For achieving the above object, design a kind of the quality control of foundation job practices based on the modulus of resilience, it is characterized in that described the quality control of foundation job practices first calculates the modulus required value of each layering by the Known designs condition, then control the roadbed quality by the mechanical performance index of controlling roadbed, concrete steps are:

A. determine road table design deflection value l _s;

B. calculate deflection value<road table design deflection value according to the road table, by calculating roadbed end face compression rebound modulu value E ₀; Described road table calculates deflection value l _scomputational methods are:

$l_S=1000\frac{2\mathrm{P\&delta;}}{E_1}{\mathrm{\&alpha;}}_{c}F,$ Wherein: ${\mathrm{\&alpha;}}_c=f(\frac{h_1}{\mathrm{\&delta;}},\frac{h_2}{\mathrm{\&delta;}},...,\frac{h_{n-1}}{\mathrm{\&delta;}},\frac{E_2}{E_1},\frac{E_3}{E_2},...,\frac{E_0}{E_{n-1}}),$

in formula: l _sfor the road table calculates deflection value, unit is: 0.01mm; F is the flexure comprehensive correction factor; The tire ground connection pressure that p is Standard of vehicle, unit is: MPa; The tire equivalent radius of circle that δ is Standard of vehicle, unit is: cm; α _cfor theoretical deflection coefficient, by dedicated program or nomogram, calculate; E ₀for roadbed end face compression rebound modulu value, unit is: MPa; E ₁, E ₂..., E _n-1for road surface layers of material compression rebound modulu value, unit is: MPa; h ₁, h ₂..., h _n-1for the road structure layer thickness, unit is: cm; Wherein, ground surface material modulus of resilience E _ican determine according to laboratory test, actual deflection value l is shown on road _sit is the supercrust thickness h _i, ground surface material modulus of resilience E _iwith roadbed end face compression rebound modulu value E ₀complicated function, actual deflection value l _sneed meet l _s<l _dcondition, can calculate by above-mentioned formula the roadbed end face compression rebound modulu value met design requirement; Calculating can adopt trial and error procedure: first draft a certain E ₀thereby value is tried to achieve F and α _cvalue, then tentative calculation deflection value l _swhether be less than design deflection value l _d; If satisfied E ₀meet the requirements; Otherwise continue tentative calculation until obtain applicable E ₀value, this calculating can adopt artificial calculating or zooming program to carry out.

C. according to E ₀value, obtain subgrade modulus hierarchical control standard by the modulus damped method; Described modulus damped method is: during roadbed design, wheel load is reduced to equivalent circle evenly distributed load, according to circular evenly distributed load stress decay curve, the roadbed top modulus of resilience is carried out along depth direction to decay in proportion, and pass through vertical stress σ in roadbed under circular evenly distributed load ₁and each layering modulus of resilience E _icalculating obtain the occurrence of modulus hierarchical control index; During the subgrade resilient modulus attenuation analysis, should deduct the equivalent depth that roadbed is converted on road surface, equivalent depth is 2.5～3m, i.e. the following position of roadbed degree of depth 2.5m～3m, vertical stress σ in roadbed under described circular evenly distributed load ₁computational methods be: σ ₁=α p, in formula: p is evenly distributed load, and unit is: kN; α is stress coefficient, when calculation level is positioned at central point below, load action place,

the radius that R is the circle of stress area, unit is: m; The roadbed degree of depth that Z converts later for the equivalent depth of considering road surface, unit is: m; Each layering modulus of resilience computational methods are: E _i=α E ₀, in formula: α is stress coefficient, when calculation level is positioned at central point below, load action place,

e _ifor the modulus of resilience at roadbed different depth place, unit is: MPa; E ₀for roadbed end face compression rebound modulu value, unit is: MPa.

D. data are processed; Described data are treated to: the decay of carrying out the modulus of resilience by circular evenly distributed load stress decay curve is calculated, and in final modulus controlling value, guarantees E ₀₄be not less than 20MPa, calculate E ₀₁, E ₀₂, E ₀₃, E ₀₄after can control and construct and select filler, fill compacting and base treatment, carry out Subgrade Compaction Quality control according to the modulus of resilience hierarchical control standard during subgrade compaction, guarantee that each layer of roadbed meets each layering modulus control criterion.

Described road table design deflection value l _dcomputational methods are: l _d=600N _e ^-0.2a _ca _sa _b, in formula: l _dfor design deflection value, unit is: 0.01mm; N _efor a track accumulative equivalent axles in design period, unit is: inferior/track; A _cfor the road quality classification coefficient, speedway, Class I highway are 1.0, and Class II highway is 1.1, three, Class IV highway is 1.2; A _sfor the surface layer genre modulus, asphalt concrete pavement is 1.0, and heat is mixed and stirred cold-mix asphalt rubble, bituminous penetration pavement, containing penetration macadam with coated chips, bituminous surface treatment, is 1.1; A _bfor the Pavement Structure coefficient, can determine road surface types according to highway pavement typical structure or standard section, semi-rigid asphalt pavement is 1.0, Asphalt Pavement with Flexible Base is 1.6.

The equivalent depth reduction formula of flexible pavement is:

in formula: Z ₀for being scaled the equivalent depth of roadbed soil layer, unit is m; h _ifor each layer thickness of road surface, unit is m; E _ifor the modulus of resilience of ground surface material, unit is MPa; E ₀for the modulus of resilience of subgrade soils, unit is MPa; M is index, for multilayer flexible pavement m=2.5.For common asphalt highway structure, the flexible pavement equivalent depth Z calculated according to above formula ₀=2.5～3.0m.

Compared with the existing technology, its advantage is that the present invention utilizes the theoretical modulus required value that each layering of roadbed is provided that calculates, and controls the roadbed quality by the mechanical performance index of direct control roadbed in the present invention.The modulus of resilience is an important mechanics parameter in approach system, directly reflects the mechanical property of roadbed, in work progress, can avoid degree of compaction possibly can't truly reflect that the rough sledding of roadbed bulk strength occurs; Each hierarchical control index is to obtain on the basis of calculating, thereby the modulus of resilience of Subgrade Construction Quality control method is more reasonable; Simultaneously, adopting the modulus of resilience to control the roadbed quality can make roadbed, road surface department be connected more close when the engineering check.

[accompanying drawing explanation]

Fig. 1 is main schematic flow sheet of the present invention;

Fig. 2 is modulus of resilience hierarchical control index schematic diagram of the present invention;

Fig. 3 is the embodiment schematic diagram of Pavement Structure Combination 6 coating systems in the embodiment of the present invention;

Wherein: 1. equivalent circle evenly distributed load 2. stress decay curve 3. roadbed layering modulus are controlled index;

Specifying Fig. 1 is Figure of abstract of the present invention.

[specific embodiment]

Below in conjunction with accompanying drawing, the invention will be further described, is very clearly the structure of this device and the principle people professional concerning this.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.

The present invention is a kind of modulus of resilience Subgrade Construction Quality control method, and it utilizes the theoretical modulus required value that each layering of roadbed is provided that calculates, and by the mechanical performance index of direct control roadbed, controls the roadbed quality.

Provide road quality classification in the Road Design charter, the known conditions such as surface layer, basic unit's grade and design life, can calculate and obtain road table design deflection value l according to above-mentioned condition _d.

L _d=600N _e ^-0.2a _ca _sa _bformula (1)

In formula: l _d--design deflection value (0.01mm);

N _e--a track accumulative equivalent axles (inferior/track) in design period;

A _c--the road quality classification coefficient, speedway, Class I highway are 1.0, Class II highway is 1.1, three, Class IV highway is 1.2;

A _s--the surface layer genre modulus, asphalt concrete pavement is 1.0, heat is mixed and stirred cold-mix asphalt rubble, bituminous penetration pavement (containing penetration macadam with coated chips), bituminous surface treatment is 1.1;

A _b--the Pavement Structure coefficient, semi-rigid asphalt pavement is 1.0, Asphalt Pavement with Flexible Base is 1.6.

There are highway pavement typical structure or standard section in each area, can determine thus Pavement Structure, supercrust thickness h _ietc. parameter.Ground surface material, as grating bituminous concrete, two grey gravels, graded broken stone etc. are manually to produce material, character is even, its modulus of resilience E _ican determine according to uniaxial compression test (cylinder method) or indoor plate-bearing test.Uniaxial compression test (cylinder method) can referring to " highway engineering pitch and Asphalt Mixture Experiment rules " (JTGE20-2011) in T0713-2000 joint; The test of the indoor modulus of resilience can referring to " highway earthwork test rule " (JTGE40-2007) in T0135-1993 joint.The modulus of resilience design reference value of conventional ground surface material also is provided simultaneously, in the appendix E of " bituminous pavement design for highway standard " (JTGD50-2006).Actual deflection value l is shown on road _sit is the supercrust thickness h _i, ground surface material modulus of resilience E _iwith the complicated function of roadbed end face compression rebound modulu value, and actual deflection value l _sneed meet l _s<l _dcondition, can calculate by formula (2) and (3) the roadbed end face compression rebound modulu value met design requirement.Calculating can adopt trial and error procedure: first draft a certain E ₀value, through type (3) is tried to achieve F and α _cvalue, the deflection value l that then tentative calculation formula (2) is definite _swhether be less than design deflection value l _d.If satisfied E ₀meet the requirements; Otherwise continue tentative calculation until obtain satisfactory E ₀value.This calculating can adopt artificial calculating or special-purpose zooming program to carry out, to simplify computational process.

$l_S=1000\frac{2\mathrm{P\&delta;}}{E_1}{\mathrm{\&alpha;}}_{c}F$ Formula (2)

Wherein:

$\begin{array}{c}{\mathrm{\&alpha;}}_c=f(\frac{h_1}{\mathrm{\&delta;}},\frac{h_2}{\mathrm{\&delta;}},...,\frac{h_{n-1}}{\mathrm{\&delta;}},\frac{E_2}{E_1},\frac{E_3}{E_2},...,\frac{E_0}{E_{n-1}})\\ F=1.63{\left(\frac{l_S}{2000\mathrm{\&delta;}}\right)}^{0.38}{\left(\frac{E_0}{p}\right)}^{0.36}\end{array}$ Formula (3)

In formula: l _s--the road table calculates deflection value (0.01mm);

F--flexure comprehensive correction factor;

The tire ground connection pressure (MPa) of p--Standard of vehicle;

The tire equivalent radius of circle (cm) of δ--Standard of vehicle

α _c--theoretical deflection coefficient, can calculate by nomogram;

E ₀--roadbed end face compression rebound modulu value (MPa);

E ₁, E ₂..., E _n-1--road surface layers of material compression rebound modulu value (MPa);

H ₁, h ₂..., h _n-1--road structure layer thickness (cm);

F is function, because this function is very complicated, therefore generally by calculating, do not obtain α _cvalue, but by nomogram (by h1/ δ, h3/ δ ..., hn-1/ δ, E2/E1, E3/E2 ..., the relation of E0/En-1 and α c is depicted as standard chart, if known, the value of front parameter just can find corresponding α c value in nomogram) solve.

On load action and road, the vertical stress of generation and strain meeting are successively decreased with the degree of depth, thereby the mode that each layer of roadbed should successively decrease from top to bottom by strength and modulus combines, and can give full play to like this ability of each structural material.Roadbed is divided into to 4 layers in this method, adopts successively from top to bottom 4 modulus of resilience hierarchical control indexs (E01, E02, E03, E04) to be controlled the construction quality of roadbed.During roadbed design, wheel load is reduced to equivalent circle evenly distributed load, according to circular evenly distributed load stress decay curve, the roadbed top modulus of resilience is carried out along depth direction to decay in proportion, to obtain the occurrence of modulus hierarchical control index.Calculate the vertical stress of inner each depth of roadbed according to the Bu Xinnaisike solution.French mathematician Bu Xinnaisike (J.Boussinesq) points out, when the foundation surface effect has vertical point load P, in ground, the stress components of any point and displacement component can solve and draw by elastic theory, and have provided concrete design formulas.These computational methods it is well known to those having skill in the art that, therefore do not do and repeat at this.Vertical stress is plotted on figure and has just obtained circular evenly distributed load stress decay curve along the degree of depth.According to the stress decay curve, the roadbed top modulus of resilience is carried out along depth direction to decay in proportion, to obtain the occurrence of modulus hierarchical control index, Fig. 2 is the distribution curve of modulus along the degree of depth.Calculate under circular Uniform Load when the vertical stress in roadbed distributes, should consider the impact of road surface on roadbed, by the road surface thickness conversion be and the connatural equivalent depth of roadbed.The equivalent depth reduction formula of flexible pavement is

$Z_0=\mathrm{\&Sigma;}{h_i}^m\sqrt{\frac{E_i}{E_0}}$

In formula: Z ₀---be scaled the equivalent depth (m) of roadbed soil layer;

H _i---each layer thickness of road surface (m);

E _i---the modulus of resilience (MPa) of ground surface material;

E ₀---the modulus of resilience (MPa) of subgrade soils;

M---index, for multilayer flexible pavement m=2.5.

For common asphalt highway structure, the flexible pavement equivalent depth Z calculated according to above formula ₀generally between 2.5～3.0m, easy on calculating, preferably by Z ₀conservative value 2.5m.

Vertical stress σ in roadbed under circular evenly distributed load ₁design formulas see formula (4).

σ ₁=α p formula (4)

In formula: p--evenly distributed load (kN);

α--stress coefficient, when calculation level is positioned at central point below, load action place, $\mathrm{\&alpha;}=1-\frac{1}{{(1+R^2/Z^2)}^{1.5}};$

The radius (m) of R--circle of stress area;

The roadbed degree of depth (m) that the equivalent depth on Z--consideration road surface converts later

Modulus of resilience decay formula adopts the reduction coefficient α identical with formula (4):

E _i＝α·E ₀ (5)

In formula: E _i--the modulus of resilience (MPa) at roadbed different depth place;

E ₀--roadbed end face compression rebound modulu value (MPa).

During the subgrade resilient modulus attenuation analysis, should deduct the equivalent depth that roadbed is converted on road surface, from the following position of roadbed degree of depth 2.5m, carry out the decay of the modulus of resilience by circular evenly distributed load stress decay curve and calculate.Final E ₀₁, E ₀₂, E ₀₃, E ₀₄result of calculation see Fig. 2 and table 1.Roadbed has requirement to the minimum strength of filler, needs to guarantee E in the modulus controlling value ₀₄be not less than 20MPa.Carry out Subgrade Compaction Quality control according to the modulus of resilience hierarchical control standard in table 1 during subgrade compaction, only need to guarantee that each layer of roadbed meets each layering modulus control criterion and get final product.

Table 1

Certain highway pavement type is asphalt concrete pavement, and Pavement Structure Combination is 6 coating systems, and as shown in Figure 3, in figure, load is that the standard double wheel axle carries BZZ-100, and h is bed thickness, and E is the modulus of resilience, and u is poisson's ratio.This pavement of road design deflection value l _dfor 0.31mm, the modulus of resilience of road surface layers of material and intensity level can be determined according to engineering experience, see Fig. 3, now only have E ₀it is unknown number.Utilize special-purpose zooming program, English lotus Shell oil company seminar develops BISAR software and repeatedly carries out tentative calculation, gets an E during each tentative calculation ₀value, E ₀carry out from small to large value according to certain difference, actual deflection value ls value is shown on the road that will obtain a correspondence, until the l that satisfies condition _s<l _dduring=0.31mm, finish to calculate, the modulus of resilience controlling value that finally obtains the roadbed end face is 40MPa.Finally according to the modulus damped method in Fig. 2, obtain subgrade modulus hierarchical control standard, the results are shown in Table 2.

During subgrade construction, its quality is just controlled according to the layering modulus value in table.Utilize standard detecting method or other method that on-the-spot loaded plate method is the modulus of resilience to carry out the modulus detection, when the modulus on road surface reaches requiring in table 1, think that this layer of Subgrade Compaction Quality is qualified.

Table 2 subgrade resilient modulus control criterion

Claims (3)

1. the quality control of foundation job practices based on the modulus of resilience, it is characterized in that described the quality control of foundation job practices first calculates the modulus required value of each layering by the Known designs condition, then control the roadbed quality by the mechanical performance index of controlling roadbed, concrete steps are:

A. determine road table design deflection value l _s;

B. calculate deflection value<road table design deflection value according to the road table, by calculating roadbed end face compression rebound modulu value E ₀; Described road table calculates deflection value l _scomputational methods are:

$l_S=1000\frac{2\mathrm{P\&delta;}}{E_1}{\mathrm{\&alpha;}}_{c}F,$ Wherein: ${\mathrm{\&alpha;}}_c=f(\frac{h_1}{\mathrm{\&delta;}},\frac{h_2}{\mathrm{\&delta;}},...,\frac{h_{n-1}}{\mathrm{\&delta;}},\frac{E_2}{E_1},\frac{E_3}{E_2},...,\frac{E_0}{E_{n-1}}),$ in formula: l _sfor the road table calculates deflection value, unit is: 0.01mm; F is the flexure comprehensive correction factor; The tire ground connection pressure that p is Standard of vehicle, unit is: MPa; The tire equivalent radius of circle that δ is Standard of vehicle, unit is: cm; α _cfor theoretical deflection coefficient, by nomogram, calculate; E ₀for roadbed end face compression rebound modulu value, unit is: MPa; E ₁, E ₂..., E _n-1for road surface layers of material compression rebound modulu value, unit is: MPa; h ₁, h ₂..., h _n-1for the road structure layer thickness, unit is: cm; Wherein, ground surface material modulus of resilience E _ican determine according to laboratory test, actual deflection value l is shown on road _sit is the supercrust thickness h _i, ground surface material modulus of resilience E _iwith the complicated function of roadbed end face compression rebound modulu value, actual deflection value l _sneed meet l _s<l _dcondition, can calculate by above-mentioned formula the roadbed end face compression rebound modulu value met design requirement, calculating can adopt trial and error procedure: first draft a certain E ₀thereby value is tried to achieve F and α _cvalue, then tentative calculation deflection value l _swhether be less than design deflection value l _d; If satisfied E ₀meet the requirements; Otherwise continue tentative calculation until obtain applicable E ₀value, this calculating can adopt artificial calculating or zooming program to carry out;

C. according to E ₀value, obtain subgrade modulus hierarchical control standard by the modulus damped method; Described modulus damped method is: during roadbed design, wheel load is reduced to equivalent circle evenly distributed load, according to circular evenly distributed load stress decay curve, the roadbed top modulus of resilience is carried out along depth direction to decay in proportion, and pass through vertical stress σ in roadbed under circular evenly distributed load ₁and each layering modulus of resilience E _icalculating obtain the occurrence of modulus hierarchical control index; During the subgrade resilient modulus attenuation analysis, should deduct the equivalent depth that roadbed is converted on road surface, equivalent depth is 2.5～3m, i.e. the following position of roadbed degree of depth 2.5m～3m; Vertical stress σ in roadbed under described circular evenly distributed load ₁computational methods be: σ ₁=α p, in formula: p is evenly distributed load, and unit is: kN; α is stress coefficient, when calculation level is positioned at central point below, load action place, the radius that R is the circle of stress area, unit is: m; The roadbed degree of depth that Z converts later for the equivalent depth of considering road surface, unit is: m; Each layering modulus of resilience computational methods are: E _i=α E ₀, in formula: α is stress coefficient, when calculation level is positioned at central point below, load action place,

e _ifor the modulus of resilience at roadbed different depth place, unit is: MPa; E ₀for roadbed end face compression rebound modulu value, unit is: MPa;

D. data are processed; Described data are treated to: the decay of carrying out the modulus of resilience by circular evenly distributed load stress decay curve is calculated, and in final modulus controlling value, guarantees E ₀₄be not less than 20MPa, calculate E ₀₁, E ₀₂, E ₀₃, E ₀₄after can control and construct and select filler, fill compacting and base treatment, carry out Subgrade Compaction Quality control according to the modulus of resilience hierarchical control standard during subgrade compaction, guarantee that each layer of roadbed meets each layering modulus control criterion.

2. a kind of the quality control of foundation job practices based on the modulus of resilience as claimed in claim 1, is characterized in that described road table design deflection value l _dcomputational methods are: l _d=600N _e ^-0.2a _ca _sa _b, in formula: l _dfor design deflection value, unit is: 0.01mm; N _efor a track accumulative equivalent axles in design period, unit is: inferior/track; A _cfor the road quality classification coefficient, speedway, Class I highway are 1.0, and Class II highway is 1.1, three, Class IV highway is 1.2; A _sfor the surface layer genre modulus, asphalt concrete pavement is 1.0, and heat is mixed and stirred cold-mix asphalt rubble, bituminous penetration pavement, containing penetration macadam with coated chips, bituminous surface treatment, is 1.1; A _bfor the Pavement Structure coefficient, can determine road surface types according to highway pavement typical structure or standard section, the structure types coefficient of semi-rigid asphalt pavement is 1.0, the structure types coefficient of Asphalt Pavement with Flexible Base is 1.6.

3. a kind of the quality control of foundation job practices based on the modulus of resilience as claimed in claim 1 is characterized in that the equivalent depth reduction formula of flexible pavement is:

in formula: Z ₀for being scaled the equivalent depth of roadbed soil layer, unit is m; h _ifor each layer thickness of road surface, unit is m; E _ifor the modulus of resilience of ground surface material, unit is MPa; E ₀for the modulus of resilience of subgrade soils, unit is MPa; M is index, for multilayer flexible pavement m=2.5.For common asphalt highway structure, the flexible pavement equivalent depth Z calculated according to above formula ₀=2.5～3.0m.

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