CN115809496A - Pile plate roadbed design method and device adjacent to existing railway bridge well digging foundation - Google Patents
Pile plate roadbed design method and device adjacent to existing railway bridge well digging foundation Download PDFInfo
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- CN115809496A CN115809496A CN202211294848.0A CN202211294848A CN115809496A CN 115809496 A CN115809496 A CN 115809496A CN 202211294848 A CN202211294848 A CN 202211294848A CN 115809496 A CN115809496 A CN 115809496A
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Abstract
The application relates to the technical field of pile slab roadbed design, in particular to a pile slab roadbed design method and device adjacent to an existing railway bridge well digging foundation, and the problem of how to design a pile slab roadbed adjacent to the existing railway bridge well digging foundation can be solved to a certain extent. The method comprises the following steps: determining multiple groups of initial structure data of the pile plate roadbed to be built, wherein each group of initial structure data is used for building a corresponding road model to be built; modeling the intersection of each road model to be built and the existing railway bridge to obtain finite element models with the same number as the road models to be built; updating the initial mechanical parameters based on each finite element model to obtain corresponding mechanical parameters to be selected; and selecting target mechanical parameters from the mechanical parameters to be selected, taking the initial structure data of the finite element model corresponding to the target mechanical parameters as target structure data, and constructing a pile slab roadbed adjacent to the existing railway bridge well digging foundation according to the target structure data.
Description
Technical Field
The application relates to the technical field of pile slab roadbed design, in particular to a pile slab roadbed design method and device adjacent to an existing railway bridge well digging foundation.
Background
The so-called pile-slab roadbed is a roadbed generally composed of "piles" and "slabs", which is currently composed of factory prefabricated plate beams and most of the frame structure of pipe piles 2, and is a roadbed form which has emerged in recent years. Compared with the traditional roadbed, the pile-plate roadbed has higher rigidity, smaller settlement and lower cost, reduces the width of a slope in the construction process, and therefore the land utilization rate is greatly improved.
The existing railway bridge is obliquely penetrated downwards by the highway based on the pile plate roadbed, when the highway roadbed is closer to the bridge pier and other structural parts of the existing railway bridge, the vehicle load on the highway roadbed can disturb the existing railway bridge foundation structure, the existing railway bridge foundation load is increased, the redundant value of the existing railway bridge foundation load is reduced, the risks of deformation and instability of the existing railway bridge structure are increased, and railway operation is seriously influenced.
The existing railway bridge foundation has the types of pile foundations, well foundations and the like, the construction of constructing the pile-slab roadbed adjacent to or below the existing railway bridge taking the pile foundations as the bridge foundation is common at present, and the construction scheme related to constructing the pile-slab roadbed adjacent to the existing railway bridge taking the well foundations as the bridge foundation in the prior art is rare, so when the well foundations are adjacent to the pile-slab roadbed, the design of the pile-slab roadbed needs to be researched to reduce the influence of the post-construction pile-slab roadbed on the structure of the existing railway bridge as much as possible.
Disclosure of Invention
The application provides a method and a device for designing a pile-slab roadbed adjacent to an existing railway bridge excavation foundation, which are used for researching how to design the pile-slab roadbed so as to reduce the influence of a post-construction pile-slab roadbed on the structure of the existing railway bridge as much as possible.
The embodiment of the application is realized as follows:
the embodiment of the application provides a method for designing a pile plate roadbed adjacent to an existing railway bridge well digging foundation, which comprises the following steps:
determining multiple groups of initial structure data of a pile plate roadbed to be built, wherein each group of initial structure data is used for building a corresponding road model to be built, and the road to be built is based on the pile plate roadbed to be built;
modeling the intersection of each road model to be built and the existing railway bridge to obtain finite element models with the same number as the road models to be built, wherein the road to be built obliquely downwards penetrates through the existing railway bridge to form the intersection;
updating initial mechanical parameters based on each finite element model to obtain mechanical parameters to be selected corresponding to each finite element model, wherein the initial mechanical parameters are determined based on existing soil parameters of the existing railway bridge and proposed soil parameters of the road model to be built;
and selecting target mechanical parameters from the mechanical parameters to be selected, wherein the initial structure data of the finite element model corresponding to the target mechanical parameters are target structure data, and constructing a pile slab roadbed adjacent to the existing railway bridge well digging foundation according to the target structure data.
In some embodiments, the initial structural data includes at least a pile length, a pile diameter of the pile-slab foundation to be constructed, and a distance between the pile-slab foundation to be constructed and the excavated foundation of the existing railroad bridge.
In some embodiments, the initial mechanical parameters include stresses and displacements to which the existing railroad bridge pier is subjected;
determining initial mechanical parameters of the finite element model based on the existing soil parameters of the existing railroad bridge and the proposed soil parameters of the proposed highway model, and further comprising:
acquiring existing soil body parameters of the existing railway bridge and presetting proposed soil body parameters of a road model to be built;
and calculating the stress and displacement of the bridge piers of the existing railway bridge based on the existing soil body parameters and the proposed soil body parameters.
In some embodiments, the candidate mechanical parameters include stress and displacement respectively suffered by the existing railroad bridge when the highway is planned to be constructed and operated, the initial mechanical parameters are updated based on each finite element model, and the candidate mechanical parameters corresponding to each finite element model are obtained, further including:
loading loads to the finite element models, and updating the initial mechanical parameters based on each finite element model loaded with the loads to obtain the stress and the displacement respectively applied to the existing railway bridge when the road to be constructed is operated;
and updating the initial mechanical parameters based on each finite element model without loading load to obtain the stress and displacement respectively applied to the existing railway bridge when the road construction is planned to be built.
In some embodiments, selecting a target mechanical parameter from the candidate mechanical parameters further includes: and selecting the mechanical parameter to be selected corresponding to the minimum stress value as a target mechanical parameter.
In some embodiments, the existing railroad bridge excavation foundation and the pile slab roadbed to be built are linear elastic material models, the soil material model of the finite element model is a molar-coulomb model, and the strength failure criterion of the finite element model is a molar-coulomb strength criterion.
In some embodiments, the soil of the existing railroad bridge comprises silt, round gravel and a well foundation, the soil parameters of the silt and the round gravel each comprise an elastic modulus, a cohesion force, an internal friction angle, a poisson's ratio and a gravity, and the soil parameters of the well foundation comprise an elastic modulus, a poisson's ratio and a gravity.
In some embodiments, the soil mass intended to construct the highway comprises the pile-slab subgrade, the soil mass parameters of the pile-slab subgrade comprise modulus of elasticity, poisson's ratio and gravity, and the modulus of elasticity of the pile-slab subgrade is greater than the modulus of elasticity of each soil mass in the existing railroad bridge.
In some embodiments, further comprising setting constraints on the finite element model, setting constraints comprising:
horizontal constraints are applied in two mutually perpendicular directions at the bottom of the finite element model, and normal constraints are applied at both sides of the finite element model.
The present application still further provides a pile slab foundation design device adjacent to an existing railroad bridge excavation foundation, including:
the system comprises a determining module, a calculating module and a calculating module, wherein the determining module is used for determining a plurality of groups of initial structure data of a pile-plate roadbed to be built, each group of initial structure data is used for building a corresponding road model to be built, and the road to be built is based on the pile-plate roadbed to be built;
the modeling module is used for modeling the intersection of each to-be-built road model and the existing railway bridge to obtain finite element models with the same number as the to-be-built road models, and the to-be-built road obliquely downwards penetrates through the existing railway bridge to form the intersection;
the parameter updating module is used for updating initial mechanical parameters based on each finite element model to obtain to-be-selected mechanical parameters corresponding to each finite element model, and the initial mechanical parameters are determined based on existing soil parameters of the existing railway bridge and proposed soil parameters of the planned road model;
and the selecting module is used for selecting target mechanical parameters from the mechanical parameters to be selected, the initial structure data of the finite element model corresponding to the target mechanical parameters is target structure data, and the pile slab roadbed is built adjacent to the existing railway bridge well digging foundation according to the target structure data.
The beneficial effect of this application: the application provides a method for designing a pile plate road bridge adjacent to an existing railway bridge well digging foundation, mechanical influence of a road to be constructed according to initial structure parameters on the existing railway bridge structure is calculated through a finite element model, the mechanical influence is expressed by the mechanical parameters to be selected, target mechanical parameters are further selected from the mechanical parameters to be selected, and when the pile plate road bed of the road to be constructed is designed according to the initial structure data of the road to be constructed corresponding to the target mechanical parameters, the influence of the pile plate road bed on the existing railway bridge structure is minimum.
Drawings
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 shows a schematic flow diagram of a method for designing a pile-slab foundation adjacent to a well excavation foundation of an existing railroad bridge according to an embodiment of the present application;
FIG. 2 is a schematic flow chart illustrating the determination of initial mechanical parameters in another embodiment of the present application;
fig. 3A shows a relationship between a roadbed distance and a vertical variation amount of piers of an existing railroad bridge during a construction period and an operation period of a pile-slab roadbed;
fig. 3B illustrates a relationship between a roadbed distance and an existing railroad bridge pier horizontal displacement amount during a pile-slab roadbed construction period and an operation period;
fig. 4 shows the relationship between different pile lengths and vertical displacement of a pier and horizontal displacement along the bridge during highway construction;
fig. 5 shows the relationship between different pile lengths and pier settlement, horizontal displacement along the bridge direction during highway operation;
FIG. 6A shows the relationship between the pile length of a pile foundation excavation pile being 5m, different pile diameters, bridge pier settlement and horizontal displacement along the bridge direction;
FIG. 6B shows the relationship between the pile length of the excavated pile of the pile foundation of 9m, different pile diameters, bridge pier settlement and horizontal displacement along the bridge direction;
fig. 7A shows the relationship between the pile length of the pile foundation excavation pile being 5m, different pile diameters, bridge pier settlement and horizontal displacement along the bridge direction during operation;
fig. 7B shows the relationship between the pile length of the excavated pile of the pile foundation of 9m, different pile diameters, bridge pier settlement and horizontal displacement along the bridge direction during operation.
Detailed Description
To make the objects, embodiments and advantages of the present application clearer, the following is a clear and complete description of exemplary embodiments of the present application with reference to the attached drawings in exemplary embodiments of the present application, and it is apparent that the exemplary embodiments described are only a part of the embodiments of the present application, and not all of the embodiments.
It should be noted that the brief descriptions of the terms in the present application are only for the convenience of understanding the embodiments described below, and are not intended to limit the embodiments of the present application. These terms should be understood in their ordinary and customary meaning unless otherwise indicated.
The terms "first," "second," "third," and the like in the description and claims of this application and in the above-described drawings are used for distinguishing between similar or analogous objects or entities and not necessarily for describing a particular sequential or chronological order, unless otherwise indicated. It is to be understood that the terms so used are interchangeable under appropriate circumstances.
The terms "comprises" and "comprising," as well as any variations thereof, are intended to cover a non-exclusive inclusion, such that a product or device that comprises a list of elements is not necessarily limited to all of the elements explicitly listed, but may include other elements not expressly listed or inherent to such product or device.
The terms "disposed" and "connected" are to be construed broadly, e.g., as meaning a fixed connection, a removable connection, or an integral connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in this application will be understood to be a specific case for those of ordinary skill in the art.
Fig. 1 is a schematic flow chart illustrating a method for designing a pile-slab foundation adjacent to a dug foundation of an existing railroad bridge according to an embodiment of the present invention, and as shown in fig. 1, the method for designing a pile-slab foundation adjacent to a dug foundation of an existing railroad bridge includes the following steps:
according to construction experience and relevant national regulations, the influence of a pile plate roadbed on the structure of an existing railway bridge and the like needs to be considered when the pile plate roadbed is constructed, for example, the influence of the distance between the pile plate roadbed to be constructed and a well digging foundation of the existing railway bridge on pier columns of the existing railway bridge, the influence of pile length pile foundations on the displacement of pier columns of the existing railway bridge during different pile length pile foundation excavation construction, the influence of pile length pile plate roadbed operation on the displacement of pier columns of the existing railway bridge, the influence of different pile diameters on the displacement of pier columns of the existing railway bridge during pile foundation excavation construction, and the influence of pile plate foundations with different pile diameters on the displacement of pier columns of the existing railway bridge.
Therefore, the initial structural data at least comprises the pile length and the pile diameter of the pile-slab roadbed to be built and the distance between the pile-slab roadbed to be built and the well digging foundation of the existing railway bridge. According to the teaching of national standards, a plurality of groups of initial structure data are set so that the method can obtain the optimal structure data, and the influence of the pile plate roadbed designed according to the optimal structure data on the existing railway bridge structure is minimum.
And 120, modeling the intersection of each road model to be built and the existing railway bridge to obtain finite element models with the same number as the road models to be built, wherein the road to be built obliquely downwards penetrates through the existing railway bridge to form the intersection.
The foundation-pile plate foundation of the highway to be constructed needs to be constructed adjacent to the foundation-pit foundation of the existing railway bridge, and then the existing railway bridge is constructed under the highway which obliquely penetrates through the railway bridge, so that the intersection of the foundation and the pile plate foundation to be constructed is modeled in order to research the influence of the foundation of the pile plate to be constructed on the existing railway bridge structure.
In the finite element model, the existing railway bridge well digging foundation and the pile plate roadbed to be built are linear elastic material models, the soil body material model of the finite element model is a mole-coulomb model, and the strength failure criterion of the finite element model is a mole-coulomb strength criterion.
In some embodiments, constraints are placed on the finite element model, the placing constraints comprising: horizontal constraints are applied in two mutually perpendicular directions at the bottom of the finite element model and normal constraints are applied at both sides of the finite element model. The finite element model is topped by a free surface without any constraints.
in some embodiments, the initial mechanical parameters include stress and displacement experienced by existing railroad bridge piers.
Fig. 2 is a schematic flow chart illustrating the process of determining initial mechanical parameters in another embodiment of the present application, and fig. 2 is a schematic flow chart illustrating the process of determining initial mechanical parameters based on existing soil parameters of an existing railroad bridge and proposed soil parameters of a road model to be constructed, including the following steps:
the existing railway bridge is constructed, so that soil parameters of the existing railway bridge can be directly obtained, the soil of the existing railway bridge comprises silt, round gravel and a well digging foundation, the soil parameters of the silt and the round gravel comprise elastic modulus, cohesive force, internal friction angle, poisson ratio and gravity, and the soil parameters of the well digging foundation comprise elastic modulus, poisson ratio and gravity.
Soil parameters of the pile plate roadbed comprise elastic modulus, poisson ratio and gravity, and the soil parameters of the road to be constructed need to be set according to construction requirements and relevant standards. It should be noted that the modulus of elasticity of the pile plate roadbed is greater than the modulus of elasticity of each soil body in the existing railway bridge.
In some embodiments, the soil parameters may be set with reference to table 1. Table 1 illustrates data for existing soil parameters and proposed soil parameters.
TABLE 1
And step 220, calculating the stress and displacement of the bridge piers of the existing railway bridge based on the existing soil body parameters and the proposed soil body parameters.
And 140, selecting target mechanical parameters from the mechanical parameters to be selected, taking the initial structure data of the finite element model corresponding to the target mechanical parameters as target structure data, and constructing a pile slab roadbed adjacent to the excavation foundation of the existing railway bridge according to the target structure data.
In some embodiments, loads are loaded to the finite element models, and the initial mechanical parameters are updated based on each loaded finite element model to obtain the stress and displacement respectively suffered by the existing railway bridge when the road operation is planned to be built. The standard of the road to be built applies a load with corresponding weight, and the applied load is used for simulating the vehicle bearing capacity of the road in operation.
In some embodiments, the initial mechanical parameters are updated based on each finite element model without loading, so as to obtain the stress and displacement respectively applied to the existing railway bridge when the road construction is planned to be built.
The method comprises the steps of calculating mechanical influence of a to-be-constructed road constructed according to initial structure parameters on the existing railway bridge structure through a finite element model, expressing the mechanical influence by the to-be-selected mechanical parameters, selecting target mechanical parameters from the to-be-selected mechanical parameters, and designing a pile plate roadbed of the to-be-constructed road according to the initial structure data of the to-be-constructed road corresponding to the target mechanical parameters, wherein the influence of the pile plate roadbed on the existing railway bridge structure is minimum.
The following are the calculations made according to the method of the present application.
(1) Influence of distance between pile foundation of pile plate roadbed and existing railway bridge well digging foundation on existing railway bridge pier stud
(1.1) influence of distance between pile foundation of pile plate roadbed and excavation foundation of existing railway bridge on vertical displacement of pier stud of existing railway bridge
For the pile plate roadbed operation period, when the roadbed distance L (namely the distance between a pile foundation of the pile plate roadbed and the excavation foundation of the existing railway bridge) is 11m, the settlement of the left side pier and the right side pier of the existing railway bridge is 0.3mm; when the roadbed distance L is 9m, the settlement of the left side pier is 0.2mm, and the settlement of the right side pier is 0.7mm; when the distance L is 7m, the settlement of the left side bridge pier is 0.1mm, and the settlement of the right side bridge pier is 1.6mm; when the roadbed distance L is 5m, the settlement of the pier on the left side is 0.1mm, and the settlement of the pier on the right side is 3.3mm. It can be seen that with the increase of the distance between the pile foundation of the pile plate roadbed and the excavation foundation of the existing railway bridge, the settlement of the pier of the existing railway bridge is gradually reduced, and the maximum displacement amount shows the trend of reduction. Fig. 3A shows a relationship between a roadbed distance and a vertical variation amount of piers of an existing railroad bridge during construction and operation of a pile-slab roadbed.
(1.2) influence of distance between pile foundation of pile plate roadbed and excavation foundation of existing railway bridge on horizontal displacement of pier stud of existing railway bridge
Along with the reduction of newly-built pile slab roadbed pile foundation and existing pier distance, the along-the-bridge direction horizontal displacement of pier increases gradually. In the road operation period, when the roadbed distance L is 11m, the maximum horizontal displacement of the left and right side piers along the bridge direction is 1.4mm; when the roadbed distance L is 9m, the maximum horizontal displacement of the bridge pier on the right side of the bridge along the bridge direction is 2.8mm; when the roadbed distance L is 7m, the maximum horizontal displacement of the bridge pier on the right side of the bridge along the bridge direction is 3.8mm; when the roadbed distance L is 5m, the maximum horizontal displacement of the bridge pier on the right side of the bridge along the bridge direction is 4.4mm.
The distance between the pile foundation of the newly-built pile plate roadbed and the well digging foundation of the existing railway bridge is relatively obvious in the influence on the horizontal displacement of the bridge foundation along the bridge direction, and the closer the pile foundation of the newly-built pile plate roadbed is to the bridge foundation, the larger the influence on the horizontal displacement of the pier stud of the existing railway bridge is. Fig. 3B shows a relationship between a roadbed distance and an existing railroad bridge pier horizontal displacement amount during a pile-slab roadbed construction period and an operation period.
(2) Influence of different pile lengths of pile slab roadbed on displacement of pier of existing railway bridge
(2.1) influence on displacement of pier of existing railway bridge during excavation construction of long pile foundations of different piles
Along with the excavation process of the pile slab roadbed foundation pit, the peripheral soil body tends to slide towards the unloading direction of the soil body, so that the peripheral earth surface is settled, and the influence of different pile foundation excavation working conditions on the existing railway bridge pier is calculated and analyzed by a finite element method.
The influence of pile foundation excavation on the displacement of an existing pier in the pile forming process is analyzed, the construction method is considered to be a row-jumping and pile-jumping construction method, the calculation is practical, the result is representative, the displacement change of the pier under the excavation condition of a single drilled pile is only considered under the action of self weight, the displacement change of the pier under the maximum excavation depth is kept unchanged at the diameter of 1.2m, the displacement change of the pier under the maximum excavation depth is respectively calculated when the pile length is 5m, 7m, 9m, 11m, 13m and 15m (namely initial structure data), and the settlement (namely vertical displacement) and the horizontal displacement along the bridge direction of the pile foundation pier excavation under different pile length conditions are obtained through calculation. Fig. 4 shows the relationship between different pile lengths and vertical displacement of bridge piers and horizontal displacement along the bridge direction during highway construction.
As shown in fig. 4, as the pile length increases, the excavation of the pile foundation causes the unloading of the soil around the pier, and further causes the settlement and horizontal displacement of the pier, wherein the settlement is increased from 1.9mm (when the pile length is 5 m) to 4.6mm (when the pile length is 15 m), and the horizontal displacement along the bridge direction is increased from 0.1mm (when the pile length is 5 m) of the pile length of 5m to 3.9mm (when the pile length is 15 m). When the excavation of the pile foundation is less than 7.5m, the change rate of the settlement of the pier of the existing railway caused by excavation along with the excavation depth is 0.05mm/m, and the change rate of the horizontal displacement along the bridge direction is 0.25mm/m. When the excavation depth is larger than 7.5m, the change rate of settlement along with the excavation depth is 0.38mm/m, and the change rate of horizontal displacement along the bridge direction is 0.42mm/m.
It can be seen that when the excavation depth is larger than 7.5m, the sedimentation change rate of the existing railway pier is increased to 0.38mm/m from 0.05mm/m, and the change rate of the horizontal displacement along the bridge is increased to 0.42mm/m from 0.25mm/m. Therefore, in the pile-forming process of the pile-slab roadbed, the settlement of the existing railway pier caused by excavation and the horizontal displacement along the bridge direction are both obviously influenced by the depth of the railway bridge foundation, and when the excavation depth exceeds the buried depth of the existing railway pier, the change rate of the settlement caused by excavation and the horizontal displacement along the bridge direction are both obviously increased.
(2.2) influence on displacement of pier of existing railway bridge during operation of long pile plate roadbed with different piles
In order to analyze the influence of different pile lengths on the displacement of the existing bridge pier, the method considers that the diameter of the pile of 1.2m is kept unchanged under the combined action of self weight and driving load, calculates the displacement changes of the pile slab roadbed and the bridge pier under the different pile lengths of 5m, 7m, 9m, 11m, 13m and 15m, and obtains the settlement (vertical displacement) of the existing railway bridge pier and the horizontal displacement along the bridge under the different pile lengths through calculation. Fig. 5 shows the relationship between different pile lengths and the settlement of a pier and the horizontal displacement along the bridge direction during the highway operation.
As can be seen from fig. 5, the maximum vertical displacement of the pier is increased from 6.1mm (when the pile length is 5 m) to 6.4mm (when the pile length is 7 m) and then to 5.8mm (when the pile length is 15 m); the maximum horizontal displacement of the pier along the bridge direction is increased to 3.0mm (when the pile length is 9 m) from 2.8mm (when the pile length is 5 m) and then reduced to 2.4mm (when the pile length is 15 m). When the pile length is less than 7.5m, the settlement and the horizontal displacement of the pier of the existing railway are increased along with the increase of the pile length, and when the pile length is more than 7.5m, the settlement and the horizontal displacement of the pier are reduced along with the increase of the pile length.
(3) Influence of different pile diameters on settlement of pier of existing railway
(3.1) influence of different pile diameters on displacement of pier of existing railway bridge during pile foundation excavation construction
In order to research the displacement influence of different pile diameters on the bridge pier in the excavation process, finite elements are used for analyzing and calculating, and a construction method of row jumping and pile jumping is adopted in construction. In order to make calculation fit practical and make the result representative, the displacement change of the pier under the excavation condition of a single drilled pile under the action of self weight is considered.
And when the pile lengths are respectively 5m and 9m, the displacement changes of the bridge piers when the pile diameters are 1.0m, 1.2m, 1.5m and 2.0m in the excavation process are calculated, and the bridge pier settlement (vertical displacement) and the bridge following direction horizontal displacement under the condition of different pile diameters of the pile foundation excavation are obtained through calculation. For example, fig. 6A shows the relationship between the length of the pile foundation excavation pile being 5m, the different pile diameters and the bridge pier settlement (vertical displacement), and the horizontal displacement along the bridge direction, and fig. 6B shows the relationship between the length of the pile foundation excavation pile being 9m, the different pile diameters and the bridge pier settlement (vertical displacement), and the horizontal displacement along the bridge direction.
As can be seen from fig. 6A, when the excavation depth is 5m, the excavation depth is smaller than the burial depth of the abutment, and as the pile diameter is increased from 1.0m to 2.0m, the settlement amount of the pier is decreased from 2.0mm to 1.8mm, and the horizontal displacement in the bridge direction is decreased from 0.4mm (when the pile diameter is 1.0 m) to 0.1mm (when the pile diameter is 2.0 m) of 2 m.
As can be seen from fig. 6B, when the excavation depth is 9m, the excavation depth is greater than the bridge foundation burial depth, and as the excavation width is increased from 1.om to 2.0m, the settlement of the piers is about 2.4mm, and the displacement in the bridge direction is about 1.4 mm. The influence of calculation accuracy is eliminated, and the influence of the pile diameter on the existing railway pier is small when the pile foundation is excavated.
(3.2) influence of pile plate roadbeds with different pile diameters on displacement of pier of existing railway bridge during operation
In order to analyze the influence of different pile diameters on the displacement of the existing bridge pier, under the combined action of the self weight and the traveling load, when the pile length is 5m and 9m respectively, the displacement changes of the pile plate roadbed and the bridge pier when the pile diameter is 1.0m, 1.2m, 1.5m and 2.0m are calculated, and the bridge pier settlement (vertical displacement) and the bridge following horizontal displacement under the conditions of different pile diameters in operation are obtained. The relation among the pile foundation excavation pile length of 5m, different pile diameters, bridge pier settlement (vertical displacement) and horizontal displacement along the bridge direction during operation is shown in fig. 7A, and the relation among the pile foundation excavation pile length of 9m, different pile diameters, bridge pier settlement (vertical displacement) and horizontal displacement along the bridge direction during operation is shown in fig. 7B.
As can be seen from FIG. 7A, when the pile length is 5m, the settlement of the bridge pier is 6.1mm as the pile diameter is increased from 1m to 2m, and the horizontal displacement along the bridge direction is reduced from 2.9mm (when the pile diameter is 1.0 m) to 2.7mm (when the pile diameter is 2.0 m).
As can be seen from FIG. 7B, when the pile length is 9m, the pier settlement is 6.1mm as the pile diameter is increased from 1.0m to 2.0m, the pier horizontal displacement is decreased from 3.1mm (when the pile diameter is 1.0 m) to 3.0mm (when the pile diameter is 2.0 m), and the amount of change is less than 4%. Therefore, the influence of calculation accuracy is eliminated, and the influence of the change of the pile diameter on the settlement of the existing railway pier and the horizontal displacement along the bridge direction is small during operation.
The comprehensive calculation result shows that the underpass highway engineering breaks the balance state of foundation soil and changes the initial coupling relation between the foundation of the existing railway bridge and the surrounding soil body. The calculation result shows that the distance between the pile plate roadbed and the bridge pier has a remarkable influence on the bridge pier, the influence is larger when the distance between the pile plate roadbed and the bridge pier is closer to the bridge pier, and the influence is close to that of the existing research, but the existing research generally sets the distance between the post-construction pile plate roadbed and the bridge pier of the existing railway bridge according to 4-6 times of the pile diameter of the post-construction pile foundation, and the calculation result is different from the obtained result of the application, and the distance between the post-construction pile plate roadbed and the bridge pier of the existing railway bridge is preferably set according to 4-9 times of the pile diameter of the post-construction pile foundation.
The calculation result also shows that the settlement and the along-bridge horizontal displacement of the existing railway pier are increased along with the increase of the maximum excavation depth of the pile foundation, and the settlement and the along-bridge horizontal displacement of the existing railway pier are gradually smaller as the pile length is increased. The settlement of the existing railway pier and the horizontal displacement along the bridge caused by excavation are both obviously influenced by the depth of the railway bridge foundation, and when the excavation depth exceeds the buried depth of the excavation foundation of the existing railway pier, the change rate of the settlement and the horizontal displacement along the bridge caused by excavation is both obviously increased.
The calculation result also shows that in order to effectively reduce the horizontal and vertical displacement influence of the pile plate roadbed on the existing structure, the pile length of the pile plate roadbed is optimized, an annular arrangement scheme is provided by comparing the arrangement of the piles with other arrangement modes, the pile plate roadbed which adopts the annular arrangement has certain effect on stabilizing the soil body and reducing the railway bridge, but the pile length is effectively reduced by increasing the number of the piles, and the expected purpose is achieved.
The method simulates the influence rule of the pile plate roadbed under different structural data on the existing railway bridge structure, and the design of the pile plate roadbed is carried out based on the influence rule, wherein the method mainly aims at reducing the influence on the piers of the existing railway bridge by selecting the distance between the pile plate roadbed and a well digging foundation, the pile length of the pile plate roadbed, the pile diameter of the pile plate roadbed and the like, and ensures the structure and the operation safety of the existing railway bridge.
The embodiment of the application further provides a rigid frame pile plate roadbed structure. The rigid frame pile plate roadbed structure consists of a reinforced concrete cast-in-place beam, a reinforced concrete cast-in-place pile and other auxiliary projects; the cast-in-situ reinforced concrete beam and the cast-in-place reinforced concrete pile are connected by reinforcing steel bars and cast into a whole, and the cast-in-situ reinforced concrete beam and the cast-in-place reinforced concrete pile are of a multi-span continuous rigid frame structure. The rigid frame structure transversely adopts a cantilever structure, and the structures such as the foundation of the existing railway bridge are effectively avoided. The rigid frame structure adopts C50 reinforced concrete, the plate thickness is 90cm, and the top position of the pile foundation is thickened to 1.5m. The reinforced concrete cast-in-place pile is designed to be in a single-row 3-pile form at the beam end of the cast-in-place beam, and the row direction is vertical to the cast-in-place beam; the reinforced concrete cast-in-place piles in the middle of the cast-in-place beam are arranged in a quincuncial shape of 7 piles, the diameter of each pile is less than or equal to 1.2m, and the minimum distance between the pile foundation of the rigid frame structure and the integral foundation of the existing railway pier is more than or equal to 4d (4.8 m).
Still another embodiment of this application provides a pile slab foundation design device of neighbouring existing railroad bridge well digging basis, includes:
the system comprises a determining module, a calculating module and a calculating module, wherein the determining module is used for determining multiple groups of initial structure data of the pile plate roadbed to be built, each group of initial structure data is used for building a corresponding road model to be built, and the road to be built is based on the pile plate roadbed to be built;
the modeling module is used for modeling the intersection of each road model to be built and the existing railway bridge to obtain finite element models with the same number as the road models to be built, and the road to be built obliquely downwards penetrates the existing railway bridge to form the intersection;
the parameter updating module is used for updating the initial mechanical parameters based on each finite element model to obtain the mechanical parameters to be selected corresponding to each finite element model, and the initial mechanical parameters are determined based on the existing soil body parameters of the existing railway bridge and the proposed soil body parameters of the road model to be built;
and the selecting module is used for selecting target mechanical parameters from the mechanical parameters to be selected, the initial structure data of the finite element model corresponding to the target mechanical parameters is target structure data, and the pile slab roadbed is built adjacent to the existing railway bridge well digging foundation according to the target structure data.
The modules can be embedded in a hardware form or independent from a processor in the computer device, and can also be stored in a memory in the computer device in a software form, so that the processor can call and execute operations corresponding to the modules.
The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the foregoing discussion in some embodiments is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed above. Many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles and the practical application, to thereby enable others skilled in the art to best utilize the embodiments and various embodiments with various modifications as are suited to the particular use contemplated.
Claims (10)
1. A design method of a pile-slab roadbed adjacent to an existing railway bridge well digging foundation is characterized by comprising the following steps:
determining multiple groups of initial structure data of a pile plate roadbed to be built, wherein each group of initial structure data is used for building a corresponding road model to be built, and the road to be built is based on the pile plate roadbed to be built;
modeling the intersection of each road model to be built and the existing railway bridge to obtain finite element models with the same number as the road models to be built, wherein the road to be built obliquely downwards penetrates through the existing railway bridge to form the intersection;
updating initial mechanical parameters based on each finite element model to obtain to-be-selected mechanical parameters corresponding to each finite element model, wherein the initial mechanical parameters are determined based on existing soil parameters of the existing railway bridge and proposed soil parameters of the road model to be built;
and selecting target mechanical parameters from the mechanical parameters to be selected, wherein the initial structure data of the finite element model corresponding to the target mechanical parameters are target structure data, and constructing a pile slab roadbed adjacent to the existing railway bridge well digging foundation according to the target structure data.
2. The method of designing a pile-slab foundation adjacent to a well excavation foundation of an existing railroad bridge of claim 1,
the initial structure data at least comprise the pile length and the pile diameter of the pile-slab roadbed to be built and the distance between the pile-slab roadbed to be built and the well digging foundation of the existing railway bridge.
3. The method of designing a pile-slab subgrade adjacent to a dug foundation of an existing railroad bridge, according to claim 1, wherein said initial mechanical parameters include stress and displacement to which said existing railroad bridge pier is subjected;
determining initial mechanical parameters of the finite element model based on the existing soil parameters of the existing railway bridge and the proposed soil parameters of the road model to be built, and further comprising:
acquiring existing soil body parameters of the existing railway bridge and presetting proposed soil body parameters of a road model to be built;
and calculating the stress and displacement of the bridge piers of the existing railway bridge based on the existing soil body parameters and the proposed soil body parameters.
4. The method of designing a pile-slab subgrade adjacent to an existing railroad bridge excavation foundation of claim 3, wherein the candidate mechanical parameters include stresses and displacements to which the existing railroad bridge is respectively subjected during construction and operation of a planned construction highway, the initial mechanical parameters are updated based on each of the finite element models, and candidate mechanical parameters corresponding to each of the finite element models are obtained, further comprising:
loading loads to the finite element models, and updating the initial mechanical parameters based on each finite element model loaded with the loads to obtain the stress and the displacement respectively suffered by the existing railway bridge when the road to be constructed is operated;
and updating the initial mechanical parameters based on each finite element model without loading load to obtain the stress and displacement respectively applied to the existing railway bridge when the road construction is planned to be built.
5. The method of designing a pile-slab subgrade adjacent to a well excavation foundation of an existing railroad bridge of claim 1, wherein selecting a target mechanical parameter from the candidate mechanical parameters further comprises: and selecting the mechanical parameters to be selected corresponding to the minimum stress value as target mechanical parameters.
6. The method of designing a pile-slab subgrade adjacent to an existing railroad bridge pit foundation of claim 1, wherein the existing railroad bridge pit foundation and the pile-slab subgrade to be constructed are linear elastic material models, the soil material model of the finite element model is a molar-coulomb model, and the strength failure criterion of the finite element model is a molar-coulomb strength criterion.
7. The method of claim 1, wherein said existing railroad bridge comprises silt, round gravel and a dug foundation, wherein said silt and said round gravel have soil parameters comprising elastic modulus, cohesion, internal friction angle, poisson's ratio and gravity, and wherein said dug foundation has soil parameters comprising elastic modulus, poisson's ratio and gravity.
8. The method of claim 7, wherein said soil mass of said road to be constructed comprises said pile plate subgrade, said pile plate subgrade having soil mass parameters including modulus of elasticity, poisson's ratio and weight, said pile plate subgrade having a modulus of elasticity greater than the modulus of elasticity of each soil mass of said existing railroad bridge.
9. The method of designing a pile-slab subgrade adjacent to an existing railroad bridge excavation foundation of claim 1, further comprising placing constraints on the finite element models, the placing constraints comprising:
horizontal constraints are applied in two mutually perpendicular directions at the bottom of the finite element model, and normal constraints are applied at both sides of the finite element model.
10. The utility model provides a be close to existing railroad bridge foundation's pile slab roadbed design device that digs well which characterized in that includes:
the system comprises a determining module, a calculating module and a calculating module, wherein the determining module is used for determining a plurality of groups of initial structure data of a pile-plate roadbed to be built, each group of initial structure data is used for building a corresponding road model to be built, and the road to be built is based on the pile-plate roadbed to be built;
the modeling module is used for modeling the intersection of each to-be-built highway model and the existing railway bridge to obtain finite element models with the same number as the to-be-built highway models, and the to-be-built highway obliquely penetrates through the existing railway bridge to form the intersection;
the parameter updating module is used for updating initial mechanical parameters based on each finite element model to obtain mechanical parameters to be selected corresponding to each finite element model, and the initial mechanical parameters are determined based on the existing soil parameters of the existing railway bridge and the proposed soil parameters of the road model to be built;
and the selecting module is used for selecting target mechanical parameters from the mechanical parameters to be selected, the initial structure data of the finite element model corresponding to the target mechanical parameters are target structure data, and the pile slab roadbed is built adjacent to the existing railway bridge well digging foundation according to the target structure data.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116484478A (en) * | 2023-04-28 | 2023-07-25 | 安徽省交通控股集团有限公司 | Design method of spliced pile plate type road |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116484478A (en) * | 2023-04-28 | 2023-07-25 | 安徽省交通控股集团有限公司 | Design method of spliced pile plate type road |
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