CN116561877A - Method for designing and calculating cement concrete pavement of road in field - Google Patents
Method for designing and calculating cement concrete pavement of road in field Download PDFInfo
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- 239000004567 concrete Substances 0.000 title claims abstract description 71
- 239000004568 cement Substances 0.000 title claims abstract description 48
- 238000000034 method Methods 0.000 title claims abstract description 26
- 230000009471 action Effects 0.000 claims abstract description 35
- 238000010276 construction Methods 0.000 claims abstract description 15
- 230000001186 cumulative effect Effects 0.000 claims abstract description 15
- 238000004364 calculation method Methods 0.000 claims abstract description 13
- 238000011065 in-situ storage Methods 0.000 claims abstract description 8
- 239000010410 layer Substances 0.000 claims description 58
- 239000011382 roller-compacted concrete Substances 0.000 claims description 10
- 239000002344 surface layer Substances 0.000 claims description 10
- 238000005192 partition Methods 0.000 claims description 6
- 230000001788 irregular Effects 0.000 abstract description 8
- 238000001228 spectrum Methods 0.000 abstract description 4
- 230000001105 regulatory effect Effects 0.000 abstract description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 abstract description 2
- 230000000694 effects Effects 0.000 description 6
- 239000000463 material Substances 0.000 description 4
- 239000002893 slag Substances 0.000 description 4
- 239000011435 rock Substances 0.000 description 3
- 238000009825 accumulation Methods 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 238000000638 solvent extraction Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000010438 granite Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 210000000323 shoulder joint Anatomy 0.000 description 1
- 239000010421 standard material Substances 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- G—PHYSICS
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/13—Architectural design, e.g. computer-aided architectural design [CAAD] related to design of buildings, bridges, landscapes, production plants or roads
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
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- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Abstract
The invention relates to the technical field of water conservancy and hydropower engineering, and provides a method for designing and calculating an in-situ road cement concrete pavement, which comprises the following steps: s1, basic data acquisition: acquiring total transportation amount and transportation vehicle data, and calculating the number of times of vehicle transportation, wherein the transportation vehicle data comprises vehicle load, vehicle axle load and axle number data; s2, calculating the cumulative action times of the design axle load: calculating the design axle load accumulated action times according to the transport vehicle data; s3, checking calculation. The invention is based on road traffic characteristics in the field, the axle load spectrum is simple and clear, the design axle load accumulated action frequency is easy to calculate and obtain, the design axle load is easy to adjust according to the actual situation, no stipulated or regulated fixed value limit exists, the invention is not limited by total construction period, daily work days, daily work shifts, irregular transportation strength and the like, the assumption of the base daily action frequency, daily work days, average annual growth rate and the like which are difficult to determine is omitted, and the result can be determined more accurately.
Description
Technical Field
The invention relates to a method for designing and calculating an in-situ road cement concrete pavement, and belongs to the technical field of hydraulic and hydroelectric engineering.
Background
The road traffic vehicles in the hydraulic and hydroelectric engineering field have large axle load, the road surface is easy to damage, and the calculation method is related to the calculation method adopted by the current design besides serious overload of the dump truck. Because the road use attribute in the hydraulic and hydroelectric engineering field is the same as the mine road, the design calculation is usually carried out by adopting GBJ 22-87 mine road design Specification, however, the specification has the following problems:
(2) the specification is formulated in 87 years, which is not updated so far, and the calculation method is old; the design of the tire pressure of the dumper for axle load and the equivalent circle diameter of the double tires of the dumper only provides data of three types of Tianjin TJ-360, beijing BJ-370 and Shanghai SH-380A, and the number of axles of the dumper is two. The number of the axles of the conventional dump truck for the hydraulic and hydroelectric engineering at present is 3 or 4, the same load is applied, the number of the axles is increased, and the axle load is greatly reduced;
(2) the standard design axle load accumulated action times are determined by the average daily action times of the axle load, the service life and the daily working days. The construction organization design rule of the water conservancy and hydropower engineering of SL 303-2004 determines the road grade according to annual traffic volume and driving density of the construction peak period, the traffic volume and driving density are peak values rather than annual average values, the traffic volume is different and irregular every year, and a plurality of assumption conditions such as the average driving density, daily work shift, annual working days, transportation vehicle model, construction period and the like are determined on assumption of the average daily traffic volume of the road design axle load in the field;
(3) the specification designs an axle load P by taking the maximum axle load as the design axle load m . The hydraulic and hydroelectric engineering often has a large part transported only once, and the vehicle with high running frequency and large axle load is a dump truck, if the axle load of the large part transportation vehicle is much larger than that of the dump truck, the axle load of the large part transportation vehicle is selected as the design axle load, (P) i /P m ）<1，（P i /P m ) After the 11 th power, the cumulative number of effects of the design axle load is severely distorted. P in the formula i I-class axle load for passing vehicles;
(4) the standard design axle load only provides 190kN, 250kN and 360kN, but the maximum full-load axle load of the dump truck for the hydraulic and hydroelectric engineering has 90KN, 130KN, 300kN and other axle loads, and the standard design axle load is single;
(5) the specification only considers the effect of the load of the vehicle, and does not consider the temperature effect, so that the calculated value is smaller;
(6) the specification is designed in a graph searching mode, the graph searching error is large, and step-by-step accumulated larger errors are formed;
(7) the elastic modulus value of the standard material is quite different from that of the current elastic modulus value.
If the design calculation is carried out by adopting the existing JTG D40-2011 road cement concrete pavement design specification, the specification application has the following problems:
(1) the axle load of the dump truck is often far more than 100kN, if 100KN in the specification is taken as the design axle load, the design axle load accumulated action times are calculated, the traffic load grade is determined, and the standard value of the flexural tensile strength of cement concrete is selected. (P) j /100）>1，（P j 100) after the 16 th power, the accumulated effective action times of the designed axle load can be severely distorted, so that the traffic load grade is judged to be wrong, and the standard value of the flexural tensile strength of the cement concrete is selected improperly. P in the formula j J-class axle load for passing vehicles;
(2) the standard design axle load cumulative action times are determined according to the base year design axle load daily action times, the traffic volume annual average increase rate and the design reference period, but the road traffic volume in the field is irregular and has no incremental, and the base year design axle load daily action times, the traffic volume annual average increase rate and the design axle load cumulative action times are difficult to determine.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for designing and calculating the road cement concrete pavement in a field, which can effectively solve the problems of improper parameter selection, inaccurate calculation, difficult determination of a reference value and the like.
The invention is realized by the following technical scheme.
The invention provides a method for designing and calculating an in-situ road cement concrete pavement, which comprises the following steps:
s1, basic data acquisition: the method comprises the steps of obtaining total transportation quantity and transportation vehicle data, and calculating to obtain the number of times of transportation of the vehicle by dividing the total transportation quantity required by the vehicle load, wherein the transportation vehicle data comprise vehicle load, vehicle axle load and axle number data, and the total transportation quantity is total transportation required during road construction in a field;
s2, calculating the cumulative action times of the design axle load: calculating the design axle load accumulated action times according to the transport vehicle dataN e =N e1 +N e2 +…+N ex +…+N en WhereinN ex The accumulated action times for the design axle load of the x-class vehicle is calculated by the following method,
wherein eta is 1 The transverse distribution coefficient of the vehicle track; η (eta) 2 Assigning coefficients to lanes, N e The number of times of action, P, is accumulated for the design axle load of all passing vehicles j For class x vehicle j axle load, P s To design the axle load, design the axle load P s Selecting the maximum axle load of the transport vehicle accounting for the main part in the transport vehicle type, and if the maximum axle load of the transport vehicle accounting for the main part in the transport vehicle type is less than 100kN, designing the axle load P s Selecting 100kN, n x The transportation times of the x-type vehicles are calculated by adopting the following modes: n is n x =Q x total /Q x In which Q x total For the total transportation quantity of the x-class vehicles, Q x The load of the class x vehicle is carried;
s3, calculating and checking: firstly simulating pavement structure layer data, and checking and adjusting thickness after calculating load fatigue stress, load maximum stress and temperature stress, wherein the pavement structure layer data comprises pavement structure type and structure layer thickness;
the transverse distribution coefficient, the lane distribution coefficient, the pavement structure type, the structure layer thickness, the load fatigue stress, the load maximum stress and the temperature stress of the vehicle track are all cited from JTG D40-2011 highway cement concrete pavement design specification.
The step S3 includes the steps of:
s3.1, calculating load fatigue stress: according to the pavement structure type and the structure layer thickness, the design axle load accumulated action times are combined, and the load fatigue stress is calculated;
s3.2, calculating the maximum load stress: selecting the maximum axle load of all transport vehicles, and calculating the maximum load stress according to the pavement structure type and the thickness of the structural layer;
s3.3, calculating temperature stress: calculating the maximum temperature stress and the temperature fatigue stress according to the natural partition where the road is located, the road surface structure type and the thickness of the structural layer;
s3.4, checking and calculating and adjusting the thickness: and determining a reliability coefficient according to the road grade, determining the concrete design flexural tensile strength according to the load fatigue stress, the load maximum stress, the maximum temperature stress and the temperature fatigue stress, checking the thickness of the structural layer of the road structure, if the checking is not satisfactory, adjusting the type of the road structure and/or the thickness of the structural layer, returning to the step S3.1, and if the checking is satisfactory, ending.
The checking calculation of the thickness of the pavement structural layer comprises the following conditions simultaneously:
a. determining a reliability coefficient gamma according to road class r And determining the design flexural tensile strength f of the cement concrete according to the load condition r For cement concrete load fatigue stress sigma pr And temperature fatigue stress sigma tr Checking gamma r (σ pr +σ tr )≤f r Meeting the requirements;
b. determining a reliability coefficient gamma according to road class r And determining the designed flexural tensile strength f of the concrete according to the load condition r Maximum stress sigma for load (p,max) And maximum temperature stress sigma (t,max) Checking gamma r (σ (p,max) +σ (t,max) )≤f r Meeting the requirements;
c. if lean concrete or roller compacted concrete base laminate or lower laminate is adopted under the cement concrete surface layer, determining the reliability coefficient gamma according to the road grade r And determining the design flexural tensile strength f of lean concrete or roller compacted concrete according to the load condition br For lean concrete or roller compacted concrete, the fatigue stress sigma is loaded bpr Checking gamma r σ bpr ≤f br Meets the requirements.
And calculating the surface layer of the middle surface of the pavement structure layer by the maximum temperature stress and the temperature fatigue stress.
The road grade determination reliability coefficient is obtained according to the importance degree of the road.
The lane allocation coefficient eta 2 The value is 1 when the two lanes are set to run in a split way and the truck only runs on one side; the N is ex There is no direction coefficient in the calculation formula.
The number of times of vehicle transportation is the number of times of going to a destination under the condition of vehicle loading, the number of times of returning to no load is equal to the number of times of vehicle transportation, and the number of times of designing axle load accumulation under the condition of no load is added into calculation.
The concrete design flexural tensile strength is determined according to the design axle load and the design axle load accumulated action times.
The invention has the beneficial effects that: based on road traffic characteristics in the field, the axle load spectrum is simple and clear, the design axle load accumulated action frequency is easy to calculate accurately, the design axle load is easy to adjust according to actual practice, no definite or regulated value limit is adopted, the limitation of total construction period, daily work days, daily work shifts, irregular transportation strength and the like is avoided, the assumption of the base daily action frequency, the daily work days, the average annual growth rate and the like which are difficult to determine is omitted, and the result can be determined more accurately.
Drawings
FIG. 1 is a schematic flow diagram of at least one embodiment of the present invention.
Detailed Description
The technical solution of the present invention is further described below, but the scope of the claimed invention is not limited to the above.
The road load in the field is concentrated in the construction period of the hydraulic and hydroelectric engineering, and the traffic characteristics are as follows: (1) the traffic volume and traffic load are large, the driving speed is low, the transportation strength is high, and the traffic is irregular and has no incremental; almost no vehicles pass after construction is finished, or even become a constituent part of social traffic, traffic load is often smaller after construction is finished. (2) In-site road traffic often has unidirectionality, such as a drainage tunnel excavates waste slag to a slag site, a truck is transported to the slag site from an excavation surface, and an empty truck is transported to the slag site from the excavation surface; the total transportation amount, the transportation vehicle type and the load design stage of the hydraulic and hydroelectric engineering construction can be determined, so that the total transportation amount, the transportation vehicle type and the load are determined specifically for a certain road.
The road surface damage is mainly fatigue damage caused by repeated load action, the total road transportation amount and the transportation vehicle type in the field and the load thereof are determined, the transportation times can be determined, and the times are the times of repeated load action on the road surface and are not limited by total construction period, daily working days, daily working shifts, irregular transportation strength and the like.
Based on the above, a first embodiment of the present invention relates to a method for designing and calculating an in-situ road cement concrete pavement, as shown in fig. 1, comprising the following steps:
s1, basic data acquisition: the method comprises the steps of obtaining total transportation quantity and transportation vehicle data, and calculating to obtain the number of times of transportation of the vehicle by dividing the total transportation quantity required by the vehicle load, wherein the transportation vehicle data comprise vehicle load, vehicle axle load and axle number data, and the total transportation quantity is total transportation required during road construction in a field;
s2, calculating the cumulative action times of the design axle load: calculating the design axle load accumulated action times according to the transport vehicle dataN e =N e1 +N e2 +…+N ex +…+N en WhereinN ex The accumulated action times for the design axle load of the x-class vehicle is calculated by the following method,
wherein eta is 1 The transverse distribution coefficient of the vehicle track; η (eta) 2 Assigning coefficients to lanes, N e The number of times of action, P, is accumulated for the design axle load of all passing vehicles j For class x vehicle j axle load, P s To design the axle load, design the axle load P s Selecting the maximum axle load of the transport vehicle accounting for the main part in the transport vehicle type, and if the maximum axle load of the transport vehicle accounting for the main part in the transport vehicle type is less than 100kN, designing the axle load P s Selecting 100kN, n x Is of the x classThe number of times of transportation of the vehicle is calculated by adopting the following mode: n is n x =Q x total /Q x In which Q x total For the total transportation quantity of the x-class vehicles, Q x The load of the class x vehicle is carried;
s3, calculating and checking: firstly simulating pavement structure layer data, and checking and adjusting thickness after calculating load fatigue stress, load maximum stress and temperature stress, wherein the pavement structure layer data comprises pavement structure type and structure layer thickness;
the lane distribution coefficient, the pavement structure type, the structure layer thickness, the load fatigue stress, the load maximum stress and the temperature stress are all cited from JTG D40-2011 highway cement concrete pavement design specification. The lane distribution coefficient is referred to as A.1.3 in JTG D40-2011 road cement concrete pavement design Specification.
Therefore, based on the characteristics of clear road traffic, clear transport vehicles and less high-frequency transport vehicle load types in practice, the axle load spectrum is simple and clear, the design axle load accumulation times are easy to calculate accurately, the design axle load is easy to adjust according to actual practice, and no definite or regulated fixed value limit is adopted.
Specifically, as a preferable scheme for more fitting the actual condition of the road pavement design in the engineering site, the pavement structure layer is at least three layers, and the type parameters of the pavement structure layer are determined according to the materials of each layer.
Preferably, the lane distribution coefficient η is preferably more suitable for the road transportation conditions in the engineering site 2 The value of the two-lane is 1 when the two-lane is set to run in a lane and the truck is only running on one side.
The second embodiment of the present invention is substantially the same as the first embodiment, with the main difference that step S3 includes the steps of:
s3.1, calculating load fatigue stress: according to the pavement structure type and the structure layer thickness, the design axle load accumulated action times are combined, and the load fatigue stress is calculated;
s3.2, calculating the maximum load stress: selecting the maximum axle load of all transport vehicles, and calculating the maximum load stress according to the pavement structure type and the thickness of the structural layer;
s3.3, calculating temperature stress: calculating the maximum temperature stress and the temperature fatigue stress according to the natural partition where the road is located, the road surface structure type and the thickness of the structural layer;
s3.4, checking and calculating and adjusting the thickness: and determining a reliability coefficient according to the road grade, determining the concrete design flexural tensile strength according to the load fatigue stress, the load maximum stress, the maximum temperature stress and the temperature fatigue stress, checking the thickness of the structural layer of the road structure, if the checking is not satisfactory, adjusting the type of the road structure and/or the thickness of the structural layer, returning to the step S3.1, and if the checking is satisfactory, ending.
Based on road traffic characteristics in the field, the maximum axle load of the transport vehicle accounting for the main share is selected as the design axle load to calculate the design axle load accumulated action times based on the total transportation amount and the transport vehicle load, the method is not limited by the total construction period, the number of working days per year, the daily working schedule, irregular transportation strength and the like, the assumption of the base annual action times, the number of working days per year, the average annual growth rate and the like which are difficult to determine is omitted, and the result can be more accurately determined.
Specifically, the road grade determination reliability coefficient is obtained according to the importance degree of the road.
Preferably, the maximum temperature stress and the temperature fatigue stress are calculated for the surface course of the surface in the pavement structure layer.
Preferably, the checking of the thickness of the pavement structure layer comprises simultaneously satisfying the following conditions:
a. determining a reliability coefficient gamma according to road class r And determining the design flexural tensile strength f of the cement concrete according to the load condition r For cement concrete load fatigue stress sigma pr And temperature fatigue stress sigma tr Checking gamma r (σ pr +σ tr )≤f r Meeting the requirements;
b. determining a reliability coefficient gamma according to road class r And determining the designed flexural tensile strength f of the concrete according to the load condition r Maximum stress sigma for load (p,max) And maximum temperature stress sigma (t,max) Checking gamma r (σ (p,max) +σ (t,max) )≤f r Meeting the requirements;
c. if lean concrete or roller compacted concrete base laminate or lower laminate is adopted under the cement concrete surface layer, determining the reliability coefficient gamma according to the road grade r And determining the design flexural tensile strength f of lean concrete or roller compacted concrete according to the load condition br For lean concrete or roller compacted concrete, the fatigue stress sigma is loaded bpr Checking gamma r σ bpr ≤f br Meets the requirements.
A third embodiment of the present invention, in combination with the above embodiment, includes the following steps:
step 1: basic information acquisition: road traffic, transport vehicle load, axle count, axle load survey.
Total transport amount × vehicle load = number of vehicle transport times, which is the number of times the load repeatedly acts on the road surface. There are several kinds of dumpers for road transportation in general field, and the total transportation quantity Q of the x-class dumpers is required x total Class-x vehicle weight Q x Number of x class vehicle transportation n x I.e. n x =Q x total /Q x The x-type vehicle is represented by the vehicle load, such as a 25-ton dump truck and a 32-ton dump truck.
Step 2: and selecting the design axle load and calculating the cumulative action times of the design axle load.
Selecting the maximum axle load of the transport vehicle accounting for the main share as a design axle load P s Meanwhile, the no-load influence of the dump truck is considered, and the push typeAnd (d) theN e =N e1 +N e2 +…+N ex +…+N en And calculating the design axle load accumulated action times. P in the formula j Representing the j-level axle load of the class i vehicle; η (eta) 1 Representing the transverse distribution coefficient of the vehicle track; η (eta) 2 Indicating a lane distribution coefficient, and taking 1 if the double lanes are set to run in a lane-dividing mode, namely the truck only runs on one side; n (N) ex Representing the design axle load accumulated action times of the X-type vehicle, N e Representing all trafficThe design axle load of the vehicle accumulates the number of times of action.
Because of unidirectionality and definiteness of road traffic in the field, N ex The calculation formula does not take the direction coefficient into consideration.
Step 3: the initial pavement structure layer and thickness are calculated to load fatigue stress sigma pr （σ pbr ）。
And (3) calculating the load fatigue stress by adopting an annex B formula of JTG D40-2011 road cement concrete pavement design specification according to the initial pavement structure layer and thickness and the design axle load accumulated action times calculated in the step (2).
Step 4: maximum load selection, calculating maximum load stress sigma p,max 。
And selecting the maximum axle load of all transport vehicles, and calculating the maximum load stress according to the structure layer and the thickness of the primary pavement by adopting an annex B formula of JTG D40-2011 road cement concrete pavement design Specification.
Step 5: based on the natural partitioning, the temperature stress is calculated.
According to the natural partition of the road and the structure layer and thickness of the primary pavement, adopting the formula of annex B of JTG D40-2011 road cement concrete pavement design Specification to calculate the maximum temperature stress sigma t,max And temperature fatigue stress sigma tr 。
Step 6: checking and adjusting the thickness.
According to the cement concrete which can be prepared by experience or engineering site, determining the flexural tensile strength f designed by cement concrete r (design flexural tensile Strength f of lean concrete or roller compacted concrete) br ) Determining a reliability coefficient gamma according to road class r . Press gamma r (σ pr +σ tr )≤f r （γ r σ pbr ≤f br ) And gamma r (σ (p,max) +σ (t,max) )≤f r Checking whether the initial pavement structure layer and the thickness meet the design requirements, and if not, adjusting the material or the thickness of the structure layer, and recalculating the load fatigue stress, the load maximum stress, the temperature stress and the like until the pavement structure layer and the thickness meet the design requirements.
The above steps of the methods are divided, for clarity of description, and may be combined into one step or split into multiple steps when implemented, so long as they include the same logic relationship, and they are all within the protection scope of this patent; it is within the scope of this patent to add insignificant modifications to the process or introduce insignificant designs, but not to alter the core design of the process.
Example 1: by adopting the embodiment, the road in a certain hydropower station is calculated, the natural partition of the road in the station is 7, and the following steps are adopted:
step 1: basic information acquisition: road traffic, transport vehicle load, axle count survey.
The maximum temperature gradient is 98 ℃/m, the field rock is mainly England rock, the England rock and granite belong to the same class, and the linear expansion coefficient is 10 multiplied by 10 -6 and/C. The road is double lanes, the transverse distribution coefficient of the wheel track is 0.5, the vehicle runs in separate lanes, and the distribution coefficient of the lane is 1. The pavement structure layer adopts: 3% of cement stabilized macadam subbase layer (elastic modulus 1300 MPa) +5% of cement stabilized macadam subbase layer (elastic modulus 2000 MPa) +cement concrete surface layer. The plate length is 5m, the material fatigue index is 0.057, the concrete shoulder joint stress reduction coefficient is 0.92, the comprehensive coefficient is 1, the concrete design flexural tensile strength is 5MPa, and the reliability coefficient is 1.07.
The comprehensive rebound modulus of the road bed top is 80MPa, the overload loading mass of a 25-ton dump truck is 32 tons, the overload loading mass of the 32-ton dump truck is 37 tons, the road traffic information in the field is shown in table 1, the loading parameters of the dump truck are shown in table 2, the loading parameters of a large transport truck are shown in table 3, and the loading parameters of a concrete mixing transport truck are shown in table 4:
；
；
；
。
step 2: and selecting the design axle load and calculating the cumulative action times of the design axle load.
The design axle load selects the maximum axle load of the main transport vehicle when the 25 ton and 32 ton dump truck is overloaded, namely: p (P) s =240kN。
The overload transportation times of the 1480 ten thousand-ton 32-ton dump truck are as follows: 1480 ten thousand tons/37 tons = 40 ten thousand times, and the design axle load accumulated action times N is no-load e1 =0.5×1× (2× (92/240) ++11 (46/240) ++11) ×40 ten thousand times=10.5 times, negligible; design of cumulative number of times N of axle load during overload e1 =0.5×1× (2× (240/240)/(11+ (120/240)/(11)) ×40 ten thousand times=40×10+4times.
The overload transportation times of the 640 ten thousand-ton 25-ton dump truck are as follows: 640 ten thousand tons/32 tons = 20 ten thousand times, and the cumulative action times N of the axle load is designed e2 =0.5×1× (2× (212/240)/(11+ (106/240)/(11) ×20 ten thousand times=5.11×10+4times.
Concrete density 2.6t/m 3 The transportation times of a 3.12 ten thousand ton concrete 6 m-wave concrete mixing transportation vehicle are 3.12/(2.6x6) =0.2 ten thousand times, and the cumulative action times N of the axle load is designed e3 =4.2x10x (-2) times, negligible.
One-time transportation of large parts, and design of accumulated axle load acting times N e4 =0.9 times, negligible.
Design the cumulative action times N of axle load e =N e1 +N e2 +N e3 +N e4 =45.12x10ζ4 times.
Step 3: and (5) initially simulating the pavement structure layer and thickness, and calculating the load fatigue stress.
The combination of the primary pavement structure layers is 15cm of the subbase layer, 13cm of the base layer and 34cm of the surface layer. According to the formula B of annex B of JTG D40-2011 road cement concrete pavement design specification, the load stress generated by the design shaft load at the critical load position is sigma ps =2.074 MPa, load fatigue stress σ pr =4.007MPa。
Step 4: and selecting the maximum load, and calculating the maximum load stress.
Comparing the axle weights, wherein the maximum load is 240kN; according to the formula of annex B of JTG D40-2011 road cement concrete pavement design specification, the load stress sigma generated by the maximum load at the critical load position is calculated pm =2.074 MPa, maximum load stress σ (p,max) =1.908MPa。
Step 5: based on the natural partitioning, the temperature stress is calculated.
The natural partition is 7, the maximum temperature gradient is 98 ℃/m, and the maximum temperature stress sigma of the surface layer is calculated according to the formula B of annex of JTG D40-2011 highway cement concrete pavement design specification (t,max) =1.27 MPa, temperature fatigue stress σ tr =0.469MPa。
Step 6: checking and adjusting the thickness.
Flexural tensile strength f of concrete design r Reliability coefficient gamma of =5 MPa r =1.07。
γ r (σ pr +σ tr )=4.790MPa≤5MPa，
γ r (σ (p,max) +σ (t,max) )=3.397MPa≤5MPa。
The initial pavement structure layer and thickness meet the requirements, and can bear the comprehensive fatigue effect of load stress and temperature stress in the design reference period and the comprehensive effect of maximum load stress of maximum axle load and maximum temperature stress of maximum temperature gradient.
According to JTG D40-2011 road cement concrete pavement design specification, considering the drainage of the base layer, adding 2cm to the design thickness of the base layer on the basis of the calculated thickness; the wearing layer is added on the surface layer, and the design thickness is added by 1cm on the basis of the calculated thickness. Therefore, the design pavement structure is three layers, namely a surface layer, a base layer and a bottom layer from top to bottom, and the related parameters are shown in table 5:
。
it follows that the invention:
(1) based on road traffic characteristics in a field, selecting the maximum axle load of the transport vehicle accounting for a main share as a designed axle load, and calculating the number of times of vehicle transportation by using the total transportation capacity and the load of the transport vehicle, wherein the number of times is not limited by the total construction period, the number of working days per year, the daily working schedule, irregular transportation strength and the like, and the assumptions of the base annual action times, the annual working days, the annual average growth rate and the like which are difficult to determine are omitted, so that the cumulative action times of the designed axle load can be accurately determined;
(2) based on the on-site road traffic and clear transportation vehicles, the high-frequency transportation vehicles have fewer vehicle load types (usually 15-ton and 25-ton self-discharging automobiles), namely the axle load spectrum is simple and clear. N (N) e Is easy to calculate accurately;
(3) the selection of the design axle load is not limited by 190kN, 250kN and 360kN of GBJ 22-87 factory and mine road design specifications, is not limited by 100kN of JTG D40-2011 road cement concrete pavement design specifications, and can be carried out according to engineering actual passing vehicles;
(4) because the axle load of the road design in the field is large, N is calculated e The traffic load grade is not judged (i.e. N is not calculated by taking 100kN as the design axle load e Judging traffic load grade), the flexural tensile strength of the cement concrete design can be a large value according to cement concrete or experience which can be prepared on the engineering site;
(5) the grafting of GBJ 22-87 factory and mine road design rule and JTG D40-2011 road cement concrete road surface design rule is completed, and the problems that GBJ 22-87 factory and mine road design rule is old and the two rules are not applicable to the road surface design in the field are solved;
(6) according to JTG D40-2011 road cement concrete pavement design specification, the temperature load effect, the maximum load effect and the material parameter value are considered, so that the actual situation is more met.
It will be understood by those skilled in the art that the foregoing embodiments are merely illustrative of the principles of the invention, and that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
Claims (8)
1. A method for designing and calculating an in-situ road cement concrete pavement is characterized by comprising the following steps of: the method comprises the following steps:
s1, basic data acquisition: the method comprises the steps of obtaining total transportation quantity and transportation vehicle data, and calculating to obtain the number of times of transportation of the vehicle by dividing the total transportation quantity required by the vehicle load, wherein the transportation vehicle data comprise vehicle load, vehicle axle load and axle number data, and the total transportation quantity is total transportation required during road construction in a field;
s2, calculating the cumulative action times of the design axle load: calculating the design axle load accumulated action times according to the transport vehicle dataN e = N e1 +N e2 +…+N ex +…+N en WhereinN ex The accumulated action times for the design axle load of the x-class vehicle is calculated by the following method,
wherein eta is 1 The transverse distribution coefficient of the vehicle track; η (eta) 2 Assigning coefficients to lanes, N e The number of times of action, P, is accumulated for the design axle load of all passing vehicles j For class x vehicle j axle load, P s To design the axle load, design the axle load P s Selecting the maximum axle load of the transport vehicle accounting for the main part in the transport vehicle type, and if the maximum axle load of the transport vehicle accounting for the main part in the transport vehicle type is less than 100kN, designing the axle load P s Selecting 100kN, n x The transportation times of the x-type vehicles are calculated by adopting the following modes: n is n x =Q x total /Q x In which Q x total For the total transportation quantity of the x-class vehicles, Q x The load of the class x vehicle is carried;
s3, calculating and checking: firstly simulating pavement structure layer data, and checking and adjusting thickness after calculating load fatigue stress, load maximum stress and temperature stress, wherein the pavement structure layer data comprises pavement structure type and structure layer thickness;
the transverse distribution coefficient, the lane distribution coefficient, the pavement structure type, the structure layer thickness, the load fatigue stress, the load maximum stress and the temperature stress of the vehicle track are all cited from JTG D40-2011 highway cement concrete pavement design specification.
2. The method for designing and calculating the on-site road cement concrete pavement according to claim 1, wherein the step S3 comprises the steps of:
s3.1, calculating load fatigue stress: according to the pavement structure type and the structure layer thickness, the design axle load accumulated action times are combined, and the load fatigue stress is calculated;
s3.2, calculating the maximum load stress: selecting the maximum axle load of all transport vehicles, and calculating the maximum load stress according to the pavement structure type and the thickness of the structural layer;
s3.3, calculating temperature stress: calculating the maximum temperature stress and the temperature fatigue stress according to the natural partition where the road is located, the road surface structure type and the thickness of the structural layer;
s3.4, checking and calculating and adjusting the thickness: and determining a reliability coefficient according to the road grade, determining the concrete design flexural tensile strength according to the load fatigue stress, the load maximum stress, the maximum temperature stress and the temperature fatigue stress, checking the thickness of the structural layer of the road structure, if the checking is not satisfactory, adjusting the type of the road structure and/or the thickness of the structural layer, returning to the step S3.1, and if the checking is satisfactory, ending.
3. The method for designing and calculating the pavement of the in-situ road cement concrete according to claim 2, wherein the checking the thickness of the pavement structure layer comprises simultaneously satisfying the following conditions:
a. determining a reliability coefficient gamma according to road class r And determining the design flexural tensile strength f of the cement concrete according to the load condition r For cement concrete load fatigue stress sigma pr And temperature fatigue stress sigma tr Checking gamma r (σ pr +σ tr )≤f r Meeting the requirements;
b. determining a reliability coefficient gamma according to road class r And determining the designed flexural tensile strength f of the concrete according to the load condition r For load ofMaximum stress sigma (p,max) And maximum temperature stress sigma (t,max) Checking gamma r (σ (p,max) +σ (t,max) )≤f r Meeting the requirements;
c. if lean concrete or roller compacted concrete base laminate or lower laminate is adopted under the cement concrete surface layer, determining the reliability coefficient gamma according to the road grade r And determining the design flexural tensile strength f of lean concrete or roller compacted concrete according to the load condition br For lean concrete or roller compacted concrete, the fatigue stress sigma is loaded bpr Checking gamma r σ bpr ≤f br Meets the requirements.
4. The method for designing and calculating the in-situ road cement concrete pavement according to claim 2, wherein the maximum temperature stress and the temperature fatigue stress calculate the surface layer in the pavement structural layer.
5. The method for designing and calculating the on-site road cement concrete pavement according to claim 2, wherein the road class determination reliability coefficient is obtained according to the road importance level.
6. The method for designing and calculating an in-situ road cement concrete pavement according to claim 1, wherein the lane distribution coefficient η 2 The value is 1 when the two lanes are set to run in a split way and the truck only runs on one side; the N is ex There is no direction coefficient in the calculation formula.
7. The method for designing and calculating the on-site road cement concrete pavement according to claim 1, wherein the number of times the vehicle is transported is the number of times the vehicle is transported to a destination under the condition of loading, the number of times of returning to no load is equal to the number of times of transporting the vehicle, and the number of times of designing the cumulative effect of the axle load under the condition of no load is added to the calculation.
8. The method for designing and calculating the on-site road cement concrete pavement according to claim 2, wherein the concrete design flexural tensile strength is determined according to the design axle load and the design axle load accumulated action times.
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| CN111962350A (en) * | 2020-09-18 | 2020-11-20 | 湖南科技大学 | Geocell reinforced cement concrete pavement structure and method for calculating thickness of surface slab |
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