CN109295826A - A kind of balanced design method of the graded broken stone Drainage Base on road surface - Google Patents
A kind of balanced design method of the graded broken stone Drainage Base on road surface Download PDFInfo
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- E—FIXED CONSTRUCTIONS
- E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
- E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
- E01C7/00—Coherent pavings made in situ
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- E01C11/00—Details of pavings
- E01C11/22—Gutters; Kerbs ; Surface drainage of streets, roads or like traffic areas
- E01C11/224—Surface drainage of streets
- E01C11/225—Paving specially adapted for through-the-surfacing drainage, e.g. perforated, porous; Preformed paving elements comprising, or adapted to form, passageways for carrying off drainage
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Abstract
The present invention provides a kind of balanced design method of the graded broken stone Drainage Base on road surface, the method includes permeance property and intensity according to graded broken stone Drainage Base, design level matches the thickness of crushed stone drainage foundation, and specifically include the minimum thickness that Drainage Base is designed according to the permeance property of Drainage Base, and go out the maximum gauge of Drainage Base according to the Intensity Design of Drainage Base, the thickness of final Drainage Base value from the data for meet the two conditions；And when designing the minimum thickness of Drainage Base, Drainage Base is divided into upper moisture content non-saturated region and the moisture content saturation region under.The present invention determines the minimum thickness of drainage requirement with this using the water level distribution situation in Boussinesq equation accurate description Drainage Base；In conjunction with the loading characteristic of Drainage Base, to determine the maximum gauge of Drainage Base.The Rational Thickness of Drainage Base is determined in terms of eventually by satisfaction draining and stress two.
Description
Technical Field
The invention belongs to the field of pavement engineering, and particularly relates to a balance design method of a graded broken stone drainage base layer of a pavement.
Background
In the rainfall process, most of water flows to the side ditches from the cross slopes and the longitudinal slopes of the road surface, and part of water permeates into the road surface through the cracks of the road surface. Therefore, a great deal of research is carried out by domestic and foreign scholars aiming at the problem of water damage of the pavement, and the arrangement of the internal drainage system of the pavement can effectively prevent diseases and prolong the service life of the pavement. In the middle of the flexible pavement structure, the graded broken stone drainage base layer is arranged, so that reflection cracks generated in the early stage of the pavement can be reduced. On the other hand, free water entering the interior of the pavement structure in various modes is the main reason for causing or accelerating pavement damage, and the drainage system in the interior of the pavement is provided with the graded broken stone drainage layer, so that moisture accumulated in the pavement structure can be timely removed, the service performance of the pavement is greatly improved, the service life of the pavement is greatly prolonged, and considerable economic benefit can be obtained.
The purpose of providing a drainage base layer in the entire pavement structure is to effectively drain water within the pavement structure to reduce the occurrence of damage, and to some extent, to dissipate pore water pressure at the bottom of the face layer or inside the face layer due to traffic load. The water infiltrated through the surface layer is collected in the drainage base layer, and then a water level with a certain height is formed in the drainage base layer. The water level height can be used as an index for evaluating the effectiveness of the drainage base layer, and a theoretical basis is provided for reasonably designing the thickness of the drainage base layer. Nowadays, a method of designing a drainage base layer having a relatively wide application range is proposed on the assumption that a drainage capacity when a stable flow is formed in the drainage base layer is equal to or greater than a water seepage amount based on a design rainfall amount (depth-of-flow), and a maximum water level height formed in the drainage base layer is used as a design thickness of the drainage base layer. On the other hand, from the viewpoint of the overall structure thickness design of the road surface, when the road surface structure scheme is determined, the structure needs to be subjected to mechanical checking calculation so as to judge whether the designed structure meets the design requirements. The existing flexible pavement structure design method in China mostly adopts a mechanical-empirical method, and the design indexes are the deflection value and the layer bottom tensile stress of a structural layer.
The strength of the drainage foundation layer is generally considered in China mainly during the thickness design of the graded broken stone drainage foundation layer, and the thickness of the graded broken stone drainage foundation layer is simply estimated according to Darcy's law, so that the drainage foundation layer is easily over-thick. In order to meet the drainage requirements of drainage base course, the thickness of graded broken stone drainage base course is designed according to depth-of-flow in the United states, but the design method of the drainage base course is not reasonable enough when the permeability of the drainage base course is determined.
Therefore, there is a need in the art for a method of designing a better graded crushed stone drainage base for pavements.
Disclosure of Invention
Therefore, the invention provides a balanced design method of a graded broken stone drainage base layer of a pavement, which comprises the steps of designing the thickness of the graded broken stone drainage base layer according to the permeability and the strength of the graded broken stone drainage base layer, and particularly designing the minimum thickness of the drainage base layer according to the permeability of the drainage base layer and the maximum thickness of the drainage base layer according to the strength of the drainage base layer, wherein the thickness of the final drainage base layer is taken from data meeting the two conditions; and when the minimum thickness of the drainage base layer is designed, the drainage base layer is divided into an upper moisture unsaturated zone and a lower moisture saturated zone.
In the existing design, the design of graded broken stone drainage base course thickness has two ideas, on one hand, satisfies the drainage requirement, confirms thickness through water level height, and on the other hand, combines mechanical strength to give design thickness. The graded broken stone drainage layer needs to meet the requirements of the two aspects, and if the drainage capacity is good, the porosity is high according to the relation with the pore parameters of the grading, so that the strength is reduced, and the deformation of the whole pavement is possibly influenced. Similarly, the grading is dense, the strength is high, and the drainage requirement may not meet the requirement. Therefore, in order to further perfect the design of the graded crushed stone drainage layer, the comprehensive permeability and strength requirements are very necessary. In the patent, firstly, the design requirements of the thickness of the drainage basic layer are combined, and a drainage basic layer design method which meets both the strength requirement and the drainage requirement is established. Secondly, when the minimum thickness of the drainage base layer is designed, the drainage base layer is divided into an upper moisture unsaturated zone and a lower moisture saturated zone, and the influence of the moisture unsaturated zone is considered, so that the design of the graded broken stone drainage base layer is more accurate and reasonable.
In a specific embodiment, when the minimum thickness of the drainage base layer is designed, the water level distribution in the drainage base layer is accurately described by adopting a Buxinesk equation or an equation converted from the Buxinesk equation.
In a specific embodiment, the minimum thickness of the drainage base layer is designed according to the representative particle size d of graded crushed stone50Porosity n and P0.075The three parameters obtain the trend of the permeability coefficient K along with the change of the three parameters, and further obtain the relation between the permeability coefficient K and the thickness of the drainage base layer so as to determine the minimum thickness of the drainage base layer.
In a specific embodiment, the indoor test establishes the relationship between the grading type of the macadam and the permeability coefficient K, and therefore obtains the trend of the permeability coefficient K along with the three parameters.
In a specific embodiment, the maximum thickness of the drainage substrate is designed according to the representative particle size d of the graded crushed stones50Porosity n and P0.075The dynamic modulus M is obtained by the three parametersrThe trend of the variation of these three parameters, and thus the dynamic modulus MrDesigning deflection and bottom tensile stress of the surface layer to determine the value range of the thickness of the drainage base layer so as toThe maximum thickness of the drainage base layer is determined.
In one specific embodiment, the indoor test establishes the grading type and dynamic modulus M of the crushed stonesrThus obtaining the dynamic modulus MrTrend with these three parameters.
In a specific embodiment, the drainage base balanced design method further comprises selecting a graded material of the graded crushed stone drainage base while designing the thickness of the drainage base.
Has the advantages that: the prior art adopts Darcy's law to estimate the thickness of the drainage basic layer, does not consider the concrete distribution of water level in the drainage basic layer, can not describe the drainage ability of the drainage basic layer rationally. The invention adopts a Boussinesq (Buxinesk) equation to accurately describe the water level distribution condition in the drainage base layer so as to determine the minimum thickness required by drainage; combining the stress characteristics of the drainage base layer, and according to the parameters representing grading performance, including the representative particle size d50Porosity n and P0.075And the thickness of the base layer is determined as a control index for determining the thickness of the base layer so as to determine the maximum thickness of the drainage base layer. Finally, the reasonable thickness of the drainage base layer is determined by meeting the drainage and stress.
Drawings
FIG. 1 is a two-dimensional road surface drainage seepage model diagram.
FIG. 2 is a schematic flow chart of a design method for balancing a drainage foundation of graded crushed stones.
Fig. 3 is a structure view of a flip-chip asphalt pavement in example 1.
Detailed Description
The purpose of the design of the pavement structure is to provide a reasonable pavement structure which is adaptive to climatic environment and geological conditions, and the obvious advantage of arranging the graded broken stone drainage base layer is that the water can be effectively drained, and the function has important significance for improving the pavement service condition and prolonging the service life of the road aiming at the climate complexity of Chinese terrain. When designing a pavement structure, the actual engineering conditions including climate, roadbed soil bearing capacity, traffic volume and materials are firstly known, some pavement structures are assumed according to the conditions, the thickness of the pavement structure layer is determined through mechanical calculation, and economic analysis is performed from a plurality of alternative schemes to determine the optimal scheme, so that the design of the structure layer is determined.
The method is used as the background, researches are carried out on the thickness design of the graded broken stone drainage layer, and the graded broken stone drainage base layer balance design method is provided by developing the permeability experiment and the large dynamic triaxial experiment research of the graded broken stone. Determining characteristic indexes including representative particle size d for grading broken stone performance based on grading design as starting point50Porosity n and P0.075(passage of particles smaller than 0.075 mm). By controlling the indexes, the method is applied to the thickness design of the graded broken stone drainage base course. The design of how the grading type influences the thickness of the drainage layer is discussed from the following two points, namely the idea of the balanced design method has two main lines:
(1) determining minimum thickness of drainage base
Based on depth-of-flow design theory, the maximum height in the drainage layer is used as the design thickness of the drainage base layer. By analyzing the calculation results of the unsaturated and drainage models, the permeability of the graded broken stone material is a main factor influencing the water level height of the drainage base under the condition of determining the permeability of the pavement. First, the saturation permeability coefficient was determined by experimental studies. Based on a one-dimensional steady-state Boussinesq equation model (the following formula 2 is a simplified version of the Boussinesq equation), the analytical solution of the water level height of the drainage layer is obtained again by considering the influence of the capillary water action.
As shown in fig. 1, the drainage base layer is divided into a saturated area and an unsaturated area, the base layer is assumed to be a watertight layer, and when the water level height forms a stable seepage surface, that is, water permeates into the drainage base layer to reach the stable seepage surface, the flow rate passing through the x-section can be represented by the following formula:
Qs(x)+Qus(x)＝Ix(1)
wherein x is the abscissa [ L ]]The coordinate value representing the transverse width direction of the drainage base layer is m, qs (x) L2T-1]And Qus (x) L2T-1]Respectively, the water flow rates in the saturated and unsaturated regions in the x-section, and I represents the permeability [ LT [ ]-1]Wherein T represents time in units of s;
the flow in the saturation region can be expressed as:
where f is (D-x) tan α, and is expressed as the height [ L ] of the non-drainage boundary from the reference plane](ii) a H is the height [ L ] of the drainage base layer relative to the reference surface]；KsRepresents the saturation permeability coefficient [ LT-1](ii) a D is the transverse width [ L ] of the drainage base layer]α denotes the slope of the substrate;
based on the Gardner soil-water characteristic curve, the macroscopic capillary water rise height can be defined as:
formula (III) αGExpressed as the parameter [ L ] of the distribution of the constituent particles of the porous medium-1]The value is 7.05; when the capillary rise plus H is greater than the sum of f and the thickness of the base drainage, the flow rate of the unsaturated zone can be expressed as:
where ψ denotes the suction (negative value) of the matrix, the sum of which with the vertical coordinate z equals the total head H; therefore, in this case, the control equation for calculating the water level height is:
the resulting water level height H is expressed as follows:
wherein,
and then, the water level height H is obtained based on an analytic solution given by the unsaturated drainage model, so that the calculation expression of the base layer thickness is as follows:
T＝H-D tanα(10)
the maximum value obtained is used as a reference value for designing the thickness of the base layer to meet the drainage performance.
Research results show that by adopting the same grading, the permeability coefficient is reduced along with the reduction of porosity, and the obtained highest water level value is increased. However, if the base layer is thicker, the tensile stress of the bottom layer of the surface layer is increased under the repeated action of load, so that the road surface is subjected to accumulated deformation to generate ruts, and therefore, the maximum thickness value of the base layer needs to be controlled.
(2) Determining a maximum thickness of a drainage substrate that meets strength requirements
Based on the theory of a pavement elastic layered system, the design of the whole pavement structure is considered, and whether the thickness of a drainage base layer meets the design requirements of pavement deflection and the bottom tensile stress of a surface layer needs to be checked. The elastic modulus is an important index for representing the strength of the graded crushed stone and is also a design technical index of the graded crushed stone material, and the elastic modulus of the graded crushed stone is linked with the porosity. It is indicated in the specifications that porosity control below 15% is recommended to ensure base course strength and overall pavement structural stability.
Because the way of designing the maximum thickness of the drainage base layer according to the strength of the drainage base layer is consistent with the prior art, the content of the invention is not described herein.
Summarizing, the fit point of the whole balance design method is the control of the characteristic parameters of gradation, the former design meets the drainage design requirements aiming at the drainage performance of the drainage material, namely, the maximum value of the formed water level height is used as the reference value of the design value; the latter is designed by considering the thickness of each structural layer of the whole pavement, the strength of the drainage base layer material meets the design requirements, namely the calculated critical thickness value meets the pavement deflection and the pavement bottom tensile stress design index, and the schematic diagram of the balanced design method is shown in fig. 2.
Example 1
Supposing that a highway is constructed on a certain road section, the design year limit is 15 years, the average traffic increase rate is 10 percent, the lane coefficient is 0.45, and the road section is positioned in a natural area IV of the highway7The consistency of the silty soil is 1.00, the width B of the road surface is 24.5, four lanes of the traffic lane are 2 multiplied by 7.5m, the traffic lane is positioned in a middle-wet road section, and a large amount of crushed stone aggregates are supplied along the road. The accumulated equivalent number (N) obtained by the axle load conversione) Is 1 × 107Secondary/lane. The dynamic modulus of the soil matrix is found to be 40MPa according to the standard. The compression modulus value of the cement stabilized macadam is 1500MPa, and the thickness is 35 cm. Assuming that the design requirements of the medium grade crushed stone have the porosity of 13 percent, the gradient of 0.2 percent and the road surface infiltration rate of 2.4 multiplied by 10-4cm/s, four gradation classes designed by the method of the present inventionAnd (5) designing the thickness of the drainage base layer. The pavement structure is shown in fig. 3.
1. Calculation of minimum thickness
Considering the influence of capillary water action in the drainage process, a non-saturated drainage model is adopted, after the permeability coefficient in a saturated area is reasonably determined according to equation (1), all parameters are substituted into a method for calculating the water level height based on equations (2) to (10) to obtain the highest water level height value, and the highest water level height value is used as the minimum thickness T meeting the drainage requirement in the drainage base layer designminSee table 1.
2. Determination of maximum thickness
(1) Calculation of deflection
The design method of the flexible asphalt pavement in China adopts a multilayer elastic layered theory under the action of double-circle vertical uniform load, the contact state of the structural layers of the pavement is completely continuous, and the deflection value and the layer bottom tensile stress of the structural layers are used as design indexes. The standard axle load adopted by the design of the asphalt flexible pavement is a double-wheel-set single-axle load of 100KN (BZZ-100). The designed deflection value is determined according to the road grade, the accumulated standard equivalent axle number within the design year, the surface layer and the base layer, and the calculation expression is as follows:
in the formula IdRepresents the design deflection value (0.01 mm); n is a radical ofeIs the cumulative equivalent axle number (secondary/lane) of one lane in the design year; a. thecThe highway grade is 1.0 of the expressway and the first-level highway; a. thesRepresenting a surface layer type coefficient, and taking 1.0 as an asphalt concrete surface layer; a. thebIs the pavement structure type coefficient, the flexible base asphalt pavement is 1.0, and the designed deflection value obtained according to the formula is 23.88 mm. Actually measuring deflection value L of road surface at wheel gap center under action of double-circle uniformly distributed loadtIs equal to the design deflection value ldAnd corrected for the theoretical deflection coefficient α1Is calculated asThe following:
wherein,
in the formula LtMeasured deflection value (mm) of road surface, P is tyre contact pressure (MPa) of standard vehicle type, 0.7MPa is taken, delta is equivalent circle radius, 10.65cm is taken, F is deflection comprehensive correction coefficient, F is 0.529, α is obtained by the above formula1Is 4.239.
(2) Calculation of the tensile stress at the bottom of a layer
The asphalt concrete layer is composed of fine grain type, medium grain type and coarse grain type dense graded concrete from top to bottom. The compression modulus of each layer is 20 ℃, the fine grain type dense graded asphalt concrete is 1400MPa, the splitting strength is 1.4MPa, and the thickness is 4 cm; the medium grain type dense-graded asphalt concrete is 1200MPa, the splitting strength is 1.0MP, and the thickness is 6 cm; the coarse grain type dense-graded concrete is 1000MPA, the splitting strength is 0.8MPa, and the thickness is 8 cm; the allowable tensile stress at the bottom of the bituminous concrete layer according to specification (JTG D50-2006) is as follows:
wherein sigmaRIndicating the allowable tensile stress (MPa) of the pavement structure layer material; sigmasIs the ultimate cleavage strength (MPa) of the asphalt concrete; ksIs the tensile strength structural coefficient. Fine grain type dense asphalt concrete:
medium-grain dense asphalt concrete:
coarse-grained dense asphalt concrete:
(3) checking and calculating deflection value and layer bottom tensile stress
The multilayer pavement structure can not directly adopt a three-layer elastic system formula and can be solved by adopting a computer program. 3. And (3) calculating the result: as shown in tables 1 and 2.
TABLE 1 minimum recommended thickness values for drainage layers of different graded crushed stone materials
TABLE 2 maximum thickness of drainage foundation determined by gravel base of different gradation
In Table 1, representsParticle diameter d50And (4) representing different grading of crushed stones, wherein different design thickness recommended ranges are given by different grading. The porosity in the design requirement is smaller than that in the calculation of the maximum thickness in the requirement of meeting the mechanical requirement, the porosity is improved, and the modulus of the drainage base layer is increased, so that the value of the maximum thickness meeting the mechanical requirement is smaller than that in the table 2.
Lower modulus of graded macadam indicates lower strength, e.g., very severely weathered graded macadam. And the graded broken stone with good quality and high strength has high modulus. When the modulus of the graded broken stone is about 300MPa, the graded broken stone is preferably used for a drainage base course of a high-grade road; and when the modulus of the graded broken stone is lower, the graded broken stone can be generally suitable for a drainage base course of a common road.
Table 1 and table 2. For example, in the graded gravel 1, when the modulus of the graded gravel is 305MPa, the maximum thickness meeting the mechanical property is less than 23cm, and the minimum thickness meeting the drainage requirement is 24cm, and obviously, the thickness value cannot meet the requirements of strength and permeability at the same time. Therefore, according to the control indexes in the balance design method, the porosity is recommended to be improved, the minimum thickness reduction of the permeability is met, the thickness value in the mechanical calculation is increased, a value range is obtained, even a thickness design value appears, the requirement of combining the design thickness of the whole pavement can be met, and the requirement of the drainage performance can also be met. In the grading 1, when the modulus of the graded broken stone is 250MPa, the thickness of the drainage base layer is 24-47 cm, but the thickness of the drainage base layer of the graded broken stone is generally required to be not more than 30cm in the specification. Therefore, the thickness of the graded crushed stone drainage base layer can be selected together according to the specific conditions by combining the factors.
Similarly, if gradation 2 is selected, the porosity can be increased when the modulus of the graded crushed stone is 336 MPa.
However, if the gradation 3 and the gradation 4 are selected, and the modulus of the gradation macadam is 322MPa and 309MPa respectively, the value range of the thickness design of the drainage base layer of the gradation macadam is 12-19 cm and 10-22 cm respectively.
The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions and substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.
Claims (8)
1. A method for designing the balance of a graded broken stone drainage basic layer of a pavement comprises the steps of designing the thickness of the graded broken stone drainage basic layer according to the permeability and the strength of the graded broken stone drainage basic layer, specifically designing the minimum thickness of the drainage basic layer according to the permeability of the drainage basic layer, designing the maximum thickness of the drainage basic layer according to the strength of the drainage basic layer, and finally obtaining the value of the thickness of the drainage basic layer from data meeting the two conditions; and when the minimum thickness of the drainage base layer is designed, the drainage base layer is divided into an upper moisture unsaturated zone and a lower moisture saturated zone.
2. The method of claim 1, wherein when designing the minimum thickness of the drainage substrate, the water level distribution in the drainage substrate is accurately described by using a Buxinesk equation or an equation transformed from the Buxinesk equation.
3. The method as claimed in claim 1, wherein the minimum thickness of the drainage bed is designed according to the representative particle size d of graded crushed stone50Porosity n and P0.075The three parameters obtain the trend of the permeability coefficient K along with the change of the three parameters, and further obtain the relation between the permeability coefficient K and the thickness of the drainage base layer so as to determine the minimum thickness of the drainage base layer.
4. A method according to claim 3, characterized in that the laboratory test establishes the relationship between the grading type of the macadam and the permeability coefficient K, thus obtaining the trend of the permeability coefficient K as a function of these three parameters.
5. The method of claim 1, wherein the maximum thickness of the drainage bed is designed according to the representative particle size d of graded crushed stone50Porosity n and P0.075The dynamic modulus M is obtained by the three parametersrThe trend of the variation of these three parameters, and thus the dynamic modulus MrAnd designing deflection and the bottom tensile stress of the surface layer to determine the value range of the thickness of the drainage base layer so as to determine the maximum thickness of the drainage base layer.
6. The method of claim 5, wherein the grading type and dynamic modulus M of the crushed stones are established by laboratory testsrThus obtaining the dynamic modulus MrTrend with these three parameters.
7. The method as claimed in any one of claims 1 to 6, wherein the method for designing the drainage foundation in a balanced manner further comprises selecting the graded material of the graded crushed stone drainage foundation while designing the thickness of the drainage foundation.
8. The method according to any one of claims 1 to 7,
the drainage basic layer is divided into a saturated area and an unsaturated area, the basic layer bottom layer is assumed to be a watertight layer, when the water level height forms a stable seepage surface, that is, when water permeates into the drainage basic layer to reach the stable seepage surface, the flow passing through the x section can be represented by the following formula:
Qs(x)+Qus(x)＝Ix (1)
wherein x is the abscissa [ L ]]The coordinate value representing the transverse width direction of the drainage base layer is m, qs (x) L2T-1]And Qus (x) L2T-1]Respectively, the water flow rates in the saturated and unsaturated regions in the x-section, and I represents the permeability [ LT [ ]-1]Wherein T represents time in units of s;
the flow in the saturation region can be expressed as:
where f is (D-x) tan α, and is expressed as the height [ L ] of the non-drainage boundary from the reference plane](ii) a H is the height [ L ] of the drainage base layer relative to the reference surface]；KsRepresents the saturation permeability coefficient [ LT-1](ii) a D is the transverse width [ L ] of the drainage base layer]α denotes the slope of the substrate;
based on the Gardner soil-water characteristic curve, the macroscopic capillary water rise height can be defined as:
formula (III) αGExpressed as the parameter [ L ] of the distribution of the constituent particles of the porous medium-1]The value is 7.05; when the sum of the capillary rise height and H is more than f and the base layer rowThe flow rate in the unsaturated zone, when the thickness of the water is summed, can be expressed as:
where ψ denotes the suction (negative value) of the matrix, the sum of which with the vertical coordinate z equals the total head H; therefore, in this case, the control equation for calculating the water level height is:
the resulting water level height H is expressed as follows:
wherein,
and then, the water level height H is obtained based on an analytic solution given by the unsaturated drainage model, so that the calculation expression of the base layer thickness is as follows:
T＝H-D tanα (10)
the maximum value obtained is used as a reference value for designing the thickness of the base layer to meet the drainage performance.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114117615A (en) * | 2021-12-02 | 2022-03-01 | 中国科学院武汉岩土力学研究所 | Method and device for determining performance of roadbed of highway section and processing equipment |
| US11847383B2 (en) | 2021-12-02 | 2023-12-19 | Institute Of Rock And Soil Mechanics, Chinese Academy Of Sciences | Method for determining a performance of an unsaturated subgrade of a multi-layered expressway section and processing device thereof |
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| CN109295826B (en) | 2021-03-12 |
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