CN111914458B - Method for controlling line shape of arch ring of reinforced concrete arch bridge - Google Patents

Abstract

The invention discloses a method for linear control of the arch circle of a reinforced concrete arch bridge. 2; S3. Calculate the vertical formwork elevation of the i-th cantilever pouring segment, and complete the pouring of the i-th cantilever pouring segment based on the vertical formwork elevation of the i-th cantilever pouring segment; S4. If i=N, set the Step S5 is executed after adding 1 to the value, if i<N, add 1 to the value of i and return to step S3; S5, calculate the installation elevation of the i-th stiff skeleton segment, based on the installation of the i-th stiff skeleton segment The construction of the ith rigid frame segment is completed at the elevation; S6, if i=M, end, if i<M, add 1 to the value of i and return to step S5. The invention can precisely control the segment line shape of the arch ring of the reinforced concrete arch bridge constructed by the cable-stayed buckle and the cantilever casting combined with the rigid skeleton.

Description

A kind of linear control method of arch circle of reinforced concrete arch bridge

technical field

The invention relates to the field of arch bridge construction, in particular to a linear control method for an arch circle of a reinforced concrete arch bridge.

Background technique

As a new technology of arch bridge construction, cable-stayed cantilever cast reinforced concrete box arch bridge has the advantages of good structural integrity, low cost, less maintenance, high construction stability, and strong spanning ability. The terrain is very suitable for the construction of cantilevered arches, so this process has great competitiveness in the western region of my country.

The construction of reinforced concrete arch bridges with cable-stayed cantilever casting combined with rigid skeletons is difficult because of its long cantilevered sections. With the increase of the length and weight of cantilever casting, temporary structures such as hanging baskets are prone to excessive stress on the rods and excessive downward deflection of the cantilever end. big. As a new construction technique of arch bridges, in the prior art, there is no method that can precisely control the segmental alignment of the arch ring of the reinforced concrete arch bridge constructed by the cable-stayed cantilever casting combined with the rigid skeleton.

Therefore, how to precisely control the formation of the segmental line of the arch ring of the reinforced concrete arch bridge constructed by the cantilever casting of the cable-stayed buckle and the cantilever combined with the rigid skeleton is an urgent problem to be solved by those skilled in the art.

SUMMARY OF THE INVENTION

Aiming at the above-mentioned deficiencies of the prior art, the technical problem actually solved by the present invention is to precisely control the segmental line shape of the arch ring of the reinforced concrete arch bridge constructed by the cable-stayed suspension cantilever casting combined with the rigid skeleton.

A reinforced concrete arch bridge arch ring linear control method, the method is suitable for a reinforced concrete arch bridge constructed by cable-stayed cantilever casting combined with a rigid skeleton, and the middle part of the arch ring of the reinforced concrete arch bridge is a rigid skeleton segment covered with concrete , the two sides are cantilever pouring sections, the cantilever pouring sections are numbered from 1 to N from the arch foot to the middle direction, and the rigid skeleton sections are sequentially numbered from the arch foot to the middle direction. N+1 to M; The linear control method of the arch circle of the reinforced concrete arch bridge includes:

S1. Obtain the arch design parameters of the reinforced concrete arch bridge;

S2. Complete the construction of the No. 1 cantilever pouring segment based on the arch design parameters of the reinforced concrete arch bridge, and set i=2;

S3. Calculate the vertical formwork elevation of the i-th cantilever pouring segment, and complete the pouring of the i-th cantilever pouring segment based on the vertical formwork elevation of the i-th cantilever pouring segment;

S4. If i=N, add 1 to the value of i and execute step S5; if i<N, add 1 to the value of i and return to step S3;

S5. Calculate the installation elevation of the i-th stiff frame segment, and complete the construction of the i-th stiff frame segment based on the installation elevation of the i-th stiff frame segment;

S6. If i=M, end, if i<M, add 1 to the value of i and return to step S5.

按下式计算：Preferably, in step S3, the vertical form elevation of the i-th cantilever casting segment

Calculate as follows:

表示第i号悬臂浇筑节段悬臂端的拱圈截面形心设计标高，

表示第i号悬臂浇筑节段悬臂端拱圈截面的设计预拱度值，

表示浇筑第i号悬臂浇筑节段时的主拱圈变形修正值，

表示浇筑第i号悬臂浇筑节段时的挂篮变形值，h表示主拱圈高度，

表示第i号悬臂浇筑节段悬臂端拱圈拱轴线水平倾角。In the formula,

Represents the design elevation of the centroid of the arch ring section at the cantilever end of the i-th cantilever casting segment,

Represents the design pre-camber value of the cantilever end arch ring section of the i-th cantilever casting segment,

Represents the deformation correction value of the main arch ring when pouring the i-th cantilever pouring segment,

represents the deformation value of the hanging basket when pouring the i-th cantilever pouring segment, h represents the height of the main arch ring,

Represents the horizontal inclination angle of the arch axis of the cantilever end arch ring of the i-th cantilever casting segment.

Preferably, the method for obtaining the design pre-camber value of a reinforced concrete arch bridge includes:

A Midas/civil model is established to obtain the mid-span design pre-camber value of the arch ring, and the design pre-camber value of the rest of the arch ring is proportionally distributed according to the horizontal thrust influence line of the arch foot.

包括浇筑第i号悬臂浇筑节段时主拱圈变形混凝土时变效应修正值

和浇筑第i号悬臂浇筑节段时现场实测温度修正值

Preferably,

Including the correction value of the time-varying effect of the deformed concrete of the main arch ring when pouring the No. i cantilever pouring segment

and the correction value of the field measured temperature when pouring the No. i cantilever pouring segment

表示基于挂篮预压荷载试验结果得到的第i号悬臂浇筑节段的挂篮变形预测值，

表示浇筑拱圈第i号悬臂浇筑节段工况下挂篮有限元仿真结果值，

表示第i-1号悬臂浇筑节段的挂篮实测变形值；Preferably,

represents the predicted value of the hanging basket deformation of the i-th cantilever pouring segment based on the preloading load test results of the hanging basket,

represents the value of the finite element simulation result of the hanging basket under the condition of the i-th cantilever pouring segment of the pouring arch ring,

Indicates the measured deformation value of the hanging basket of No. i-1 cantilever pouring segment;

其中，a和b均为常数项，G₂表示拱圈第2号悬臂浇筑节段的重量，G_i表示第i号悬臂浇筑节段拱圈的重量；Based on the test results of the preloading load of the hanging basket, the measured deformation value of the hanging basket under each graded load is recorded, and the mapping relationship between the graded load and the hanging basket deformation is obtained, and the predicted value of the hanging basket deformation of the i-th cantilever pouring segment can be obtained by linear fitting.

Among them, a and b are both constant terms, G ₂ represents the weight of the No. 2 cantilever pouring segment of the arch ring, and G _i represents the weight of the arch ring of the No. i cantilever pouring segment;

The finite element simulation model of the hanging basket under the condition of the No. i cantilever pouring section is established. The wet weight load of the arch ring of the No. i cantilever pouring section is simulated by line load, and the diaphragm of the arch ring is simulated by concentrated force.

作为

The measured deformation value of the hanging basket of the No. i-1 cantilever pouring segment

as

按下式计算：Preferably, in step S5, the installation elevation of the i-th rigid frame segment

Calculate as follows:

表示第i号劲性骨架节段悬臂端的拱圈截面形心设计标高，

表示第i号劲性骨架节段悬臂端拱圈截面的设计预拱度值，

表示安装第i号劲性骨架节段时现场实测温度修正值，h'表示型钢劲性骨架节段桁高，

表示第i号劲性骨架节段悬臂端拱圈拱轴线水平倾角，δ'_{阶段/步骤实际总位移}表示主拱圈分阶段施工有限元仿真模型中安装第i号劲性骨架节段施工阶段劲性骨架节段悬臂端控制点的阶段/步骤实际总位移值。In the formula,

Represents the design elevation of the centroid of the arch ring section at the cantilever end of the i-th stiff skeleton segment,

represents the design pre-camber value of the cantilever end arch ring section of the i-th stiffness skeleton segment,

Represents the correction value of the temperature measured on site when the No. ith stiff frame segment is installed, h' represents the girder height of the section steel stiff frame segment,

Represents the horizontal inclination of the arch axis of the arch ring at the cantilever end of the stiff skeleton segment No. i, and the _{actual total displacement of the δ' stage/step} represents the construction stage of the installation of the stiff skeleton segment No. i in the finite element simulation model of the staged construction of the main arch ring. Phase/step actual total displacement value for the cantilever end control points of the skeleton segment.

In summary, the present invention discloses a method for controlling the linear shape of the arch ring of a reinforced concrete arch bridge. The method is suitable for a reinforced concrete arch bridge constructed by cable-stayed cantilever casting combined with a rigid skeleton. The middle part of the arch ring of the reinforced concrete arch bridge is It is the rigid skeleton segment of the outer concrete, and the two sides are cantilever pouring segments. The cantilever pouring segments are numbered from 1 to N from the arch foot to the middle direction, and the rigid skeleton segments are numbered from the arch foot to the middle direction. is N+1 to M; the linear control method for the arch circle of the reinforced concrete arch bridge includes: S1, obtaining the arch design parameters of the reinforced concrete arch bridge; S2, completing the construction of the No. 1 cantilever pouring section based on the arch design parameters of the reinforced concrete arch bridge, setting i=2; S3. Calculate the vertical formwork elevation of the i-th cantilever pouring segment, and complete the pouring of the i-th cantilever pouring segment based on the vertical formwork elevation of the i-th cantilever pouring segment; S4. If i=N, set the Step S5 is executed after adding 1 to the value of i. If i<N, add 1 to the value of i and return to step S3; S5, calculate the installation elevation of the i-th stiff skeleton segment, based on the i-th stiff skeleton segment Complete the construction of the i-th stiff skeleton segment at the installation elevation of 1; S6, if i=M, end, if i<M, add 1 to the value of i and return to step S5. The invention can precisely control the segment line shape of the arch ring of the reinforced concrete arch bridge constructed by the cable-stayed buckle and the cantilever casting combined with the rigid skeleton.

Description of drawings

In order to make the purpose, technical solutions and advantages of the invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:

Fig. 1 is the flow chart of a kind of reinforced concrete arch bridge arch loop linear control method disclosed by the present invention;

Fig. 2 is the structural representation of the arch bridge of a specific example in the present invention;

Fig. 3 is the sectional view of the arch foot corresponding to the arch bridge in Fig. 2;

Fig. 4 is the standard sectional view corresponding to the arch bridge in Fig. 2;

Fig. 5 is the longitudinal pouring sequence diagram of the arch ring of the closing section corresponding to the arch bridge in Fig. 2;

Fig. 6 and Fig. 7 are the horizontal pouring sequence diagrams of the arch ring of the closing section corresponding to the arch bridge in Fig. 2;

Figure 8 is a front view of the new triangular truss hanging basket;

Figure 9 is a side view of the new triangular truss hanging basket;

Fig. 10 is the schematic diagram of the coordinate system of arch circle coordinate calculation in the present invention;

Figure 11 is a schematic diagram of the reaction force-displacement reciprocal theorem;

Figure 12 is the layout diagram of the anchor end of the hanging basket load test;

Figure 13 is a schematic diagram of the finite element simulation model of the hanging basket under the condition of pouring the No. i cantilever pouring segment;

Figure 14 is a comparison diagram of the theoretical value and the measured value of the linear shape of the main arch after the method of the present invention is used to linearly control the arch bridge in Figure 2, and the loose cable is formed into an arch;

Figure 15 is a schematic diagram of the local coordinate system and parameters of the main arch ring.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings.

As shown in FIG. 1 , the present invention discloses a method for controlling the linear shape of the arch ring of a reinforced concrete arch bridge. This method is suitable for a reinforced concrete arch bridge constructed by cable-stayed cantilever casting combined with a rigid skeleton. The middle part is the rigid skeleton segment covered with concrete, and the two sides are cantilever pouring segments. The cantilever pouring segments are numbered from 1 to N from the arch foot to the middle direction, and the rigid skeleton segment is numbered from the arch foot to the middle direction. The sequence is N+1 to M; the reinforced concrete arch bridge arch circle linear control method includes:

S1. Obtain the arch design parameters of the reinforced concrete arch bridge;

S2. Complete the construction of the No. 1 cantilever pouring segment based on the arch design parameters of the reinforced concrete arch bridge, and set i=2;

S3. Calculate the vertical formwork elevation of the i-th cantilever pouring segment, and complete the pouring of the i-th cantilever pouring segment based on the vertical formwork elevation of the i-th cantilever pouring segment;

S4. If i=N, add 1 to the value of i and execute step S5; if i<N, add 1 to the value of i and return to step S3;

S5. Calculate the installation elevation of the i-th stiff frame segment, and complete the construction of the i-th stiff frame segment based on the installation elevation of the i-th stiff frame segment;

S6. If i=M, end, if i<M, add 1 to the value of i and return to step S5.

Taking the arch bridge shown in Figure 2 as an example, the span arrangement is 2×30+17×13.2 (main span 210m)+3×30m, and the total length of the bridge is 391.4m. The main bridge is a top-loaded reinforced concrete box arch bridge with a net span of 210m, a net sag height of 42m, a net sag-span ratio of 1/5, and the arch axis adopts a catenary, and the arch axis coefficient m=1.67. One side of the approach bridge is a 2×30m prestressed concrete simply supported and then structurally continuous T beam, and the other side approach is a 3×30 prestressed concrete first simply supported and then structurally continuous T beam. The plane of the main bridge is located on a straight line, and the longitudinal plane of the main bridge is located on a convex curve with i=±0.5% and R=25445.380m.

Except for the positions of No. 1 and No. 14 columns, the transverse partitions of the corresponding arch ring box girder are 35 cm thick, and the other positions are 35 cm; the transverse partitions between the bent columns are all 25 cm. Dry in the box, set φ5cm drainage holes at the arches in the box, at the chamfers of the diaphragm and the bottom plate, and at the bottom of the diaphragm; set φ5cm ventilation holes on the top plate of the web.

The construction buckle cable of the arch ring is set at the position of the diaphragm at the end of each segment, and the anchoring device adopts the fixed end round P anchor. After the construction of the main arch ring, the buckle cable should be cut off, and the cable hole should be filled with grouting.

As shown in Figure 3 and Figure 4, the arch ring is a single box and single chamber section, with a width of 7.0m and a height of 3.5m. The thickness of the top and bottom plate of the cast-in-place section of the arch foot bracket is gradually changed from 80cm to 40cm, and the thickness of the web plate is gradually changed from 80cm to 50cm. The other segments of the arch ring are 40cm behind the top and bottom plates, and the web thickness is 50cm.

The main arch ring is constructed by the combination method of cantilever casting and rigid skeleton. The No. 1 segment of the arch ring is cast in place with full-height brackets, and the No. 2 to No. 14 segments of the arch ring are cast by cantilevered cantilevers. The buckle and hanging cantilever was poured to the No. 14 section, and the remaining 24.65m closed section used steel structure to form a steel truss arch, and no additional anchor cables were added. Finally, the steel truss arch was outsourced with concrete to complete the closure of the main arch of the bridge. The Helong strength skeleton is divided into 3 sections, the first section is pre-buried in the concrete of No. 14 arch ring, and the second and third sections are hoisted and spliced as a whole. The construction process of sections 2 to 14 is as follows:

①When the concrete of the nth segment reaches the design strength, tension the nth group of buckles and anchor cables;

② Move the hanging basket to the pouring position of the n+1th segment;

③Pour the n+1th segment.

Taking into account the existing construction capacity and convenience of construction, the pouring of the outsourcing concrete adopts the following scheme: low-temperature sub-ring pouring the arch ring closing section, and two working faces are simultaneously and symmetrically pouring the arch box bottom plate and 1/2 web concrete. After the strength, the arch box roof and 1/2 web concrete are poured symmetrically in two working planes. Figure 5, Figure 6 and Figure 7 show the vertical and horizontal concrete pouring sequence diagrams of the arch ring in the Helong section.

In order to meet the problems of length and weight in the construction of this project, a new type of triangular truss hanging basket (as shown in Figure 8 and Figure 9) is proposed, which mainly includes the main truss load-bearing system and the main truss load-bearing system. A pair of C-shaped hooks are arranged on the left and right sides of the middle part. The top of the C-shaped hook is connected with a walking device. The bottom of the walking device is located on the walking track on the top of the arch box of the poured segment. The C-shaped hook is provided with a connecting plate. The connecting plate The left and right sides are connected with the pull seats located on the sides of the front basket and the rear basket of the main truss load-bearing system through a plurality of cable-stayed slings. The rear basket is provided with an anti-roller device, and the main truss load-bearing system is provided with a lifting load-bearing anchor boom. . The upper and lower chords of the hanging basket are composed of trusses made of profiled steel, which are connected to the hook pins through steel slings. The hooks are welded box-shaped sections of steel plates. The hooks are only stressed when the hanging basket is walking. The wet weight is borne by the anchor boom.

Compared with the traditional hanging baskets used in overhanging reinforced concrete arch bridges, the new triangular hanging baskets can extend the length of overhanging to an unprecedented 8m, achieve a maximum inclination angle of 39.6°, and bear the weight of overhanging 188t. The device is simple, the force is clear, and the structure is efficient. In addition, the existing hanging basket anchor rod is usually anchored on the bottom plate of the cantilever end of the arch ring. In order to improve the mechanical performance of the cantilever of the arch ring segment, the new triangular truss hanging basket moves the anchoring position of the anchor hanger from the bottom plate of the arch ring to the top plate of the arch ring . Various loads such as concrete wet weight are also transmitted to the top plate of the arch ring through the hanging basket anchor rod, realizing the transformation from the tension at the web of the arch ring segment to the compression at the top plate of the arch ring, and the local stress of the arch ring segment is significantly improved. , the main tensile stress of the arch ring is significantly reduced. The new triangular truss hanging basket is used for the new technology of the cantilevered construction of the arch ring segment, which ensures the smoothness and smoothness of the line in the cantilever construction of the arch ring, and ensures the construction safety and construction quality of the arch bridge.

For a box-arch bridge of equal height, the elevation of any section of the main arch ring can be calculated according to its arch axis equation, section height, and section inclination angle of the arch ring.

Establish the xoy coordinate system as shown in Figure 10, and set the arch axis equation of the arch ring as:

f表示计算矢高；ξ为计算系数，

L表示计算跨径。In the formula: m is the arch axis coefficient; k is the calculation coefficient,

f represents the calculated vector height; ξ is the calculation coefficient,

L represents the calculation span.

The formula for calculating the horizontal inclination angle at the position x from the vault is:

Let the height of the main arch ring be h, when the cross section of the arch ring has the same height, the height of the back of the arch y _is :

The corresponding x-coordinates are:

However, during construction drawing design and bridge construction, the origin of the coordinate system is often established at the center of the arch foot section, as shown in the XOY coordinate system in Figure 10. At this time, the coordinate of the arch axis from the X position is:

In specific implementation, for the arch ring established in the XOY coordinate system, the vertical mold elevation of the centroid of the cantilever end section of the arch ring of the i-th cantilever casting segment is:

按下式计算：However, in the actual cantilevered construction process, when the concrete vertical form of the arch ring segment is positioned, it is often controlled by the bottom edge elevation of the box girder section at the cantilever end of the arch ring. Therefore, in step S3, for the XOY coordinate system, the ith cantilever Elevation of vertical formwork for pouring segment

Calculate as follows:

表示第i号悬臂浇筑节段悬臂端的拱圈截面形心设计标高，

表示第i号悬臂浇筑节段悬臂端拱圈截面的设计预拱度值，

表示浇筑第i号悬臂浇筑节段时的主拱圈变形修正值，

表示浇筑第i号悬臂浇筑节段时的挂篮变形值，h表示主拱圈高度，

表示第i号悬臂浇筑节段悬臂端拱圈拱轴线水平倾角。In the formula, in the formula,

Represents the design elevation of the centroid of the arch ring section at the cantilever end of the i-th cantilever casting segment,

Represents the design pre-camber value of the cantilever end arch ring section of the i-th cantilever casting segment,

Represents the deformation correction value of the main arch ring when pouring the i-th cantilever pouring segment,

represents the deformation value of the hanging basket when pouring the i-th cantilever pouring segment, h represents the height of the main arch ring,

Represents the horizontal inclination angle of the arch axis of the cantilever end arch ring of the i-th cantilever casting segment.

The distance from the bottom edge of the arch ring to the center of the arch foot section is:

The following is the specific process of calculating the vertical mold elevation:

(1) According to the design and construction drawings, obtain the main arch ring net span L _o , net sag height f ₀ , arch axis coefficient m, arch ring height H, section truss height h' of section steel stiffening skeleton, and elevation h ₀ of the arching line;

获取计算系数k；(2) According to the formula

Get the calculation coefficient k;

主拱圈计算跨径

主拱圈计算矢高

主拱圈拱脚截面水平倾角

如果

则令

重新计算，直至

退出循环；(3) Make the horizontal inclination angle of the arch axis of the cantilever end arch ring of the No. i cantilever casting segment

Calculated span of main arch ring

Calculate the sag height of the main arch ring

The horizontal inclination angle of the arch foot section of the main arch ring

if

order

recalculate until

exit the loop;

主拱圈计算矢高

(4) Calculated span of main arch ring

Calculate the sag height of the main arch ring

(5) As shown in Figure 15, take the position of the arching line of the arch as the origin, take the direction of the large mileage as the positive direction of the X axis, and take the vertical upward direction as the positive direction of the Y axis to establish a local coordinate system. Enter the x-coordinate value X0Ceni at the axis position of the cantilever end arch of the i segment of the arch ring, then

(6) The vertical formwork elevation of the cantilevered segment of the arch ring is

需由施工监控单位进行复核确认。通常拱桥设计预拱度值由3部分组成：拱圈自重、拱上建筑及桥面板、二期铺装等恒载下拱圈变形，10年收缩、徐变作用后拱圈变形及二分之一静活载下拱圈最大下挠值。通过建立Midas/civil模型，求取拱圈跨中设计预拱度值，拱圈其余位置设计预拱度值则按拱脚水平推力影响线成比例分布。When implemented,

It needs to be reviewed and confirmed by the construction monitoring unit. Usually the arch bridge design pre-camber value is composed of three parts: the self-weight of the arch ring, the building on the arch and the bridge deck, the deformation of the arch ring under constant load such as the second-stage pavement, the deformation of the arch ring after 10 years of shrinkage and creep, and the half of the arch ring. The maximum deflection value of the arch ring under a static live load. By establishing the Midas/civil model, the design pre-camber value at the mid-span of the arch ring is obtained, and the design pre-camber value at the rest of the arch ring is proportionally distributed according to the horizontal thrust influence line of the arch foot.

There are usually two ways to obtain the horizontal thrust influence line of the arch foot:

1) According to the definition of the influence line of structural mechanics, by using a unit force P=1, let it pass through each point on the bridge deck (if the finite element method is used, it will act on each node on the bridge deck one by one), The required element (internal force, displacement, reaction force, etc.) is calculated in turn, and the influence line is obtained. Assuming that the bridge deck has n nodes, n loads and n calculations are required. This method is less efficient.

2) Use the reaction force-displacement reciprocal theorem to calculate the influence line of the support reaction force. As shown in FIG. 11 , it is assumed that the bridge deck has n nodes, and m (m=1, 2, 3, . . . , n) is any one of the nodes. According to the reaction force-displacement reciprocal theorem, the reaction force Rkm of the support k caused by the unit force P=1 acting at the m point is equal to the unit displacement Δk=1 of the support k in the direction of Rkm caused by the direction P=1. The displacement (in the direction along Rkm is positive).

According to the definition of the influence line, the reaction force Rkm of the support k caused by the unit force P=1 acting at the m point is the value of the influence line of the support reaction force Rk at m. Since m is any node on the bridge deck, the value of the influence line of the reaction force Rk at each point is the deflection δmk at each point of the bridge deck caused by Δk=1, that is,

Rkm(m=1,2,3,...,n)=δmk(m=1,2,3,...,n)

Therefore, using the reaction force-displacement reciprocal theorem, the problem of finding the influence line of the reaction force becomes the problem of finding the deflection caused by the unit displacement of the support.

A finite element model of bare arch is established, so that the arch foot has a forced displacement of the longitudinal bridge unit, and the vertical deflection value of each node of the arch ring in the model is obtained at this time, which is the value of the horizontal thrust influence line value of the arch foot.

包括浇筑第i号悬臂浇筑节段时主拱圈变形混凝土时变效应修正值

和浇筑第i号悬臂浇筑节段时现场实测温度修正值

When implemented,

Including the correction value of the time-varying effect of the deformed concrete of the main arch ring when pouring the No. i cantilever pouring segment

and the correction value of the field measured temperature when pouring the No. i cantilever pouring segment

为分阶段施工拱圈节段有限元仿真模型拆除所有扣、锚索工况下各控制点(拱圈各节段悬臂端)累计位移值(考虑混凝土时变效应)与拱圈一次成拱时各控制点位移值(无法考虑混凝土时变效应)的差值。斜拉扣挂悬臂浇筑结合劲性骨架施工钢筋混凝土拱桥由于施工历时较长，混凝土时变效应显著，主拱圈分阶段施工过程中，在采用应力、线形双控情况下，难以保证松索成拱线形与一次成拱线形吻合，因此需要对主拱圈节段施工高程进行混凝土时变效应修正。

In order to construct the finite element simulation model of the arch ring segment in stages, the cumulative displacement value of each control point (cantilever end of each segment of the arch ring) under the condition of removing all buckles and anchor cables (considering the time-varying effect of concrete) is the same as the time when the arch ring is once arched. The difference between the displacement values of each control point (the time-varying effect of concrete cannot be considered). Due to the long construction time and the significant time-varying effect of concrete, the cable-stayed cantilever pouring combined with the rigid skeleton construction of the reinforced concrete arch bridge is difficult to ensure the formation of the loose cable during the staged construction of the main arch ring. The arch line shape is consistent with the primary arch line shape, so it is necessary to correct the concrete time-varying effect on the construction elevation of the main arch ring segment.

的方法包括：基于已经建立的分阶段施工拱圈节段有限元仿真模型，选择浇筑拱圈第i号悬浇节段施工阶段，保存当前施工阶段有限元仿真模型为一个单独静力模型，对主拱圈进行升温/降温处理(温度改变量为任意的单位变化量)，获取温度改变与拱圈第i号悬浇节段控制点(节段悬臂端)位移变化映射关系。在浇筑拱圈第i号悬浇节段混凝土前，开展拱圈第i-1号悬浇节段位置现场温度测量，基于单位温度改变与拱圈第i号悬浇节段控制点(悬臂端位置)位移变化映射关系，获取主拱圈变形温度修正值。Obtain

The method includes: based on the established finite element simulation model of the staged construction of the arch ring segment, selecting the construction stage of the i-th cantilevered segment of the pouring arch ring, saving the finite element simulation model of the current construction stage as a separate static model, The main arch ring is heated/cooled (the temperature change is an arbitrary unit change), and the mapping relationship between the temperature change and the displacement change of the control point (cantilever end of the segment) of the i-th cantilevered segment of the arch ring is obtained. Before pouring the concrete of the i-th cantilevered segment of the arch ring, carry out the on-site temperature measurement at the position of the i-1 cantilevered segment of the arch ring. position) displacement change mapping relationship to obtain the deformation temperature correction value of the main arch ring.

表示基于挂篮预压荷载试验结果得到的第i号悬臂浇筑节段的挂篮变形预测值，

表示浇筑拱圈第i号悬臂浇筑节段工况下挂篮有限元仿真结果值，

表示第i-1号悬臂浇筑节段的挂篮实测变形值；When implemented,

represents the predicted value of the hanging basket deformation of the i-th cantilever pouring segment based on the preloading load test results of the hanging basket,

represents the value of the finite element simulation result of the hanging basket under the condition of the i-th cantilever pouring segment of the pouring arch ring,

Indicates the measured deformation value of the hanging basket of No. i-1 cantilever pouring segment;

其中，a和b均为常数项，G₂表示拱圈第2号悬臂浇筑节段的重量，G_i表示第i号悬臂浇筑节段拱圈的重量；Based on the test results of the preloading load of the hanging basket, the measured deformation value of the hanging basket under each graded load is recorded, and the mapping relationship between the graded load and the hanging basket deformation is obtained, and the predicted value of the hanging basket deformation of the i-th cantilever pouring segment can be obtained by linear fitting.

Among them, a and b are both constant terms, G ₂ represents the weight of the No. 2 cantilever pouring segment of the arch ring, and G _i represents the weight of the arch ring of the No. i cantilever pouring segment;

After the hanging basket is assembled on the 1# segment of the arch ring, in order to ensure the construction quality and safety, the preloading test must be carried out on the hanging basket before the construction of the next process to check whether the carrying capacity of the hanging basket meets the design requirements and verify the hanging basket. The rationality of the design, and the preload test can eliminate the inelastic deformation of the hanging basket and obtain the elastic deformation value of graded loading. Taking the arch bridge shown in Figure 2 as an example, the specific operation steps of the load test are as follows:

(1) The test is carried out by setting vertical anchor cables on the original ground, and the steel strands pull the hanging basket in reverse. After the hanging basket is assembled, the test is carried out with the 2# segment load.

(2) After the 1# segment is poured, as shown in Figure 12, construct 4 vertical anchor cables (single anchor cable adopts 6φj15.24mm steel strand) at both ends of the bottom beam, and the length of the anchor cable is 17m , 19m, and the length of anchoring into the rock shall not be less than 10m. When the anchor cable is tensioned, a concrete base of 50 × 50 × 30 cm is poured on the original ground, and a 2I40b I-beam box is installed on the top surface of the base. Tension the anchor cable and grouting the anchor cable hole.

(3) After the 1# segment is tensioned, remove the 1# cast-in-place bracket, assemble the hanging basket (the bottom mold is not installed), and install two 2I40b I-beam boxes on the top surface of the cantilever end of the hanging basket as a reverse pull Longitudinal beams, and leveling steel boxes are welded at the corresponding positions on the top surface of the longitudinal beams, and a total of 4 leveling steel boxes are arranged.

(4) Vertical steel bundle for installation load test, a single vertical steel bundle is made of 4φj15.24mm steel strand, the lower end is the fixed end, which is anchored on the steel box on the top surface of the base, and the upper end is the tensioning end, which is anchored in On the leveling steel box on the top side rail of the hanging basket.

(5) The weight of the 2# segment is 1886KN. Add to the graded load, observe the settlement value of the front end of the hanging basket, and check whether there is any abnormality in the connection between the structures of the hanging basket. Carry out the next level of tensioning, and after the final tensioning reaches 120%, check again whether the hanging basket is abnormal, observe the settlement of the front end of the hanging basket, pause for 60 minutes, and start unloading after no abnormality.

As shown in Figure 13, the finite element simulation model of the hanging basket under the condition of pouring the No. i cantilever pouring segment is established. Force simulation, we can get

作为

The measured deformation value of the hanging basket of the No. i-1 cantilever pouring segment

as

The actual deformation of the hanging basket should be calculated according to the difference between the elevations of the measuring points before and after the concrete is poured, that is,

In the formula, H _{before pouring} and H _{after pouring} are the elevations of the same measuring point before and after the concrete pouring of the arch ring segment.

In the formula, the calculation method of the deformation before pouring minus after pouring is adopted, so the actual deformation of the obtained hanging basket is a positive value.

The following points should be paid attention to in the elevation measurement before and after the concrete pouring of the arch ring segment:

1) To obtain the actual deformation value of the hanging basket, the elevation measurement must be carried out before and after the concrete of the arch ring segment is poured. The measurement should be carried out in a period when the air temperature is relatively stable and the temperature field of the cross section of the arch ring is relatively stable, that is, before the sun comes out in the morning. When the weather is cloudy, due to the relatively small change in temperature difference, the time period can be flexibly selected to carry out the measurement.

2) Since the cantilever poured concrete arch bridge adopts the construction method of fixed arch foot, and the rigidity of the section of the arch ring is large, the deformation value of the hanging basket is relatively small during the construction of the first few sections. In order to reduce the error caused by the measuring instrument, the precision level should be preferred for measurement.

3) With the increase of segmental concrete pouring, the deformation of the arch ring increases correspondingly. At this time, the level measurement is still preferred. When the measurement is difficult, the total station measurement can be considered.

劲性骨架实际施工过程中，为切线拼装、焊接，不存在挂篮施工，因此

因此，步骤S5中，第i号劲性骨架节段的安装标高

按下式计算：In the specific implementation, since the reinforced concrete arch bridge is constructed with a rigid skeleton in a certain length in the middle of the span of the cable-stayed cantilever casting combined with the rigid skeleton, and because it is made of steel, there is no time-varying effect of concrete, so

In the actual construction process of the rigid skeleton, it is tangentially assembled and welded, and there is no hanging basket construction, so

Therefore, in step S5, the installation elevation of the i-th rigid frame segment

Calculate as follows:

表示第i号劲性骨架节段悬臂端的拱圈截面形心设计标高，

表示第i号劲性骨架节段悬臂端拱圈截面的设计预拱度值，

表示安装第i号劲性骨架节段时现场实测温度修正值，h'表示型钢劲性骨架节段桁高，

表示第i号劲性骨架节段悬臂端拱圈拱轴线水平倾角，δ'_{阶段/步骤实际总位移}表示主拱圈分阶段施工有限元仿真模型中安装第i号劲性骨架节段施工阶段劲性骨架节段悬臂端控制点的阶段/步骤实际总位移值。In the formula,

Represents the design elevation of the centroid of the arch ring section at the cantilever end of the i-th stiff skeleton segment,

represents the design pre-camber value of the cantilever end arch ring section of the i-th stiffness skeleton segment,

Represents the correction value of the temperature measured on site when the No. ith stiff frame segment is installed, h' represents the girder height of the section steel stiff frame segment,

Represents the horizontal inclination of the arch axis of the arch ring at the cantilever end of the stiff skeleton segment No. i, and the _{actual total displacement of the δ' stage/step} represents the construction stage of the installation of the stiff skeleton segment No. i in the finite element simulation model of the staged construction of the main arch ring. Phase/step actual total displacement value for the cantilever end control points of the skeleton segment.

According to (1) to (5) in the specific calculation process of the vertical formwork elevation, the installation elevation of the segmental control point (the top edge of the segment cantilever end) of the mid-span stiff skeleton of the arch ring can be expressed as:

Taking the arch bridge shown in FIG. 2 as an example, using the method disclosed in the present invention, in terms of the shape of the arch ring, the whole bridge is tested after the main arch ring is closed and the anchor cable is removed. Middle and inside. The maximum difference between the measured value and the theoretical value is only 2.5cm, which meets the requirements of the specification, which proves that the linear shape of the main arch ring is well controlled and there is no "saddle shape". Figure 14 shows the line shape of the main arch after the loose cable is arched.

In addition, in the present invention, after the pouring of each cantilever pouring segment is completed, the poured segment can also be inspected by its height after pouring and the height after tensioning of buckles and anchor cables.

则第i号悬臂浇筑节段的混凝土浇筑完成后的拱圈顶缘高程为：After the concrete of the arch ring is poured, under the action of the wet weight of the concrete of the segment, the hanging basket will be deformed downward. The actual deformation of the hanging basket after the concrete pouring of the i-th cantilever pouring segment is:

Then the top edge elevation of the arch ring after the concrete pouring of the i-th cantilever pouring segment is:

It can be seen from the formula:

时，即挂篮理论变形与挂篮实测变形一致，此时，拱圈顶缘测点高程可简化为when

, that is, the theoretical deformation of the hanging basket is consistent with the measured deformation of the hanging basket. At this time, the elevation of the measuring point at the top edge of the arch ring can be simplified as

设两者的差值为In general, the theoretical deformation of the hanging basket is not equal to the measured deformation of the hanging basket, that is,

Let the difference between the two be

时，Δf_挂篮变形＞0，表示挂篮理论变形值偏大；when

When Δf _{hanging basket deformation} > 0, it means that the theoretical deformation value of hanging basket is too large;

时，Δf_挂篮变形＜0，表示挂篮理论变形值偏小。when

When Δf _{hanging basket} deformation is less than 0, it means that the theoretical deformation value of hanging basket is too small.

However, the above two situations can be expressed by the formula, that is, the elevation of the measuring point at the top edge of the arch ring of the i-th cantilever pouring segment is:

It is very important to measure the deformation value of the hanging basket every time. With the increase of the number of segments, the inclination of the segment gradually decreases, and the wet weight of the previous segment also decreases due to the inclination of the segment, and the wet weight is close to the vertical. The straight (gravity) direction is applied to the basket.

After the concrete of the arch ring reaches the design strength, it can be tensioned symmetrically, graded and synchronously according to the buckled cable force and the anchor cable force calculated by monitoring. Due to the action of the buckle force, the segment of the arch ring will deflect upward. According to the deformation relationship, the calculation formula of the top edge elevation of the i-th segment after the tension is completed is:

where:

The Δf _{tension deformation} is the difference (displacement) of the deformation between the buckle cable after tension and before tension.

During the simulation calculation of the finite element software model, the "cumulative displacement" of the segment should be extracted for the arch ring constructed by the cast-in-place method, and its value is represented by the _{cumulative displacement} of δ.

Due to the combined action of systematic errors, accidental errors, environmental errors and measurement errors, the actual measured elevation often differs from the theoretically calculated elevation.

In order to solve the measurement error caused by the difference between the two measuring points before and after, fixed measuring points should be set on the arch ring, and obvious marks should be made. Every time you measure, it is always fixed on the measuring point, thereby solving the problem of different measuring points.

Since the elevation measuring point is placed on the bottom mold of the arch ring base plate when the cantilevered section is in the vertical form, once the pouring is completed, the elevation measuring point needs to be transferred to the top edge of the arch back, and a fixed point on the arch ring needs to be set up. Measuring point.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described with reference to the preferred embodiments of the present invention, those of ordinary skill in the art should Various changes in the above and in the details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims (2)

1. The linear control method is characterized in that the method is suitable for a reinforced concrete arch bridge constructed by combining inclined pull buckle hanging cantilever casting with a stiff framework, the middle part of an arch ring of the reinforced concrete arch bridge is a stiff framework section wrapped with concrete, two sides of the arch ring are cantilever casting sections, the number of the cantilever casting sections from arch feet to the middle direction is sequentially 1 to N, and the number of the stiff framework section from the arch feet to the middle direction is sequentially N +1 to M; the method for controlling the arch ring line shape of the reinforced concrete arch bridge comprises the following steps:

s1, acquiring design parameters of the reinforced concrete arch bridge arch;

s2, completing construction of the No. 1 cantilever casting segment based on the design parameters of the reinforced concrete arch bridge arch, and setting i to 2;

s3, calculating the vertical formwork elevation of the ith cantilever casting section, and completing the casting of the ith cantilever casting section based on the vertical formwork elevation of the ith cantilever casting section; in step S3, the vertical formwork level of the i-th cast-in-place cantilever segment

Calculated as follows:

in the formula,

showing the designed elevation of the center of the arch ring section of the cantilever end of the No. i cantilever casting section,

the design pre-camber value of the cantilever end arch ring section of the No. i cantilever casting section is shown,

the main arch ring deformation correction value when the No. i cantilever casting segment is cast is shown,

the deformation value of the cradle when the No. i cantilever casting segment is cast is shown, h is the height of the main arch ring,

representing the horizontal inclination angle of the arch axis of the arch ring at the cantilever end of the No. i cantilever casting section;

wherein,

correction value of time-varying effect of main arch ring deformed concrete during casting of No. i cantilever casting section

And the corrected value of the on-site measured temperature when the No. i cantilever casting segment is cast

Showing the predicted hanging basket deformation value of the i-th cantilever casting segment obtained based on the hanging basket pre-pressing load test result,

showing the hanging basket finite element simulation result value under the working condition of casting the No. i cantilever casting section of the arch ring,

the measured deformation value of the hanging basket of the i-1 th cantilever casting section is represented;

based on the cradle pre-pressing load test result, recording the cradle actual measurement deformation value under each graded load, obtaining the graded load and cradle deformation mapping relation, and obtaining the cradle deformation prediction value of the No. i cantilever casting segment by adopting linear fitting

Wherein a and b are both constant terms, G₂Denotes the weight of the No. 2 arch ring cast-in-place segment, G_iRepresenting the weight of the i-th cast-in-place cantilever segment arch ring;

establishing a cradle finite element simulation model under the working condition of casting the i-th cantilever casting section, simulating the concrete wet load of the arch ring of the i-th cantilever casting section by adopting a linear load, and simulating the diaphragm plate of the arch ring by adopting a concentrated force to obtain the concrete suspension bracket finite element simulation model

Actually measured deformation value of hanging basket adopting No. i-1 cantilever casting segment

As

S4, if i is equal to N, step S5 is executed by adding 1 to the value of i, and if i is less than N, step S3 is returned to by adding 1 to the value of i;

s5, calculating the installation elevation of the ith stiff skeleton segment, and finishing the construction of the ith stiff skeleton segment based on the installation elevation of the ith stiff skeleton segment; in step S5, the installation elevation of the i-th stiff skeleton segment

Calculated as follows:

in the formula,

showing the designed elevation of the center of the arch ring section of the cantilever end of the No. i stiff skeleton section,

the design pre-camber value of the cantilever end arch ring section of the No. i stiff skeleton section is shown,

the temperature correction value measured on site when the No. i stiff skeleton section is installed is shown, h' represents the truss height of the section steel stiff skeleton section,

representing horizontal inclination angle delta of cantilever end arch ring arch axis of No. i stiff skeleton segment'_{Actual total displacement of stage/step}Representing the actual total displacement value of the stage/step of installing the cantilever end control point of the stiff framework segment in the construction stage of the ith stiff framework segment in the finite element simulation model for the staged construction of the main arch ring

S6 is terminated if i is equal to M, and if i < M, the value of i is added by 1, and the process returns to step S5.

2. The reinforced concrete arch bridge arch ring line shape control method of claim 1, wherein the method for obtaining the design pre-arch degree value of the reinforced concrete arch bridge comprises:

and establishing a Midas/civil model, solving a design pre-camber value in the arch ring span, wherein the design pre-camber values at the other positions of the arch ring are distributed in proportion to the arch springing horizontal thrust influence line.

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