阅读说明：本技术 输电线路联合板杆双锚板基础结构的下板的设计方法 (Transmission line of electricity combines the design method of the lower plate of the double anchor slab foundation structures of plate stem ) 是由 李炎隆 雒亿平 于 2019-08-27 设计创作，主要内容包括：本发明公开了一种输电线路联合板杆双锚板基础结构的下板的设计方法,双锚板基础固定结构包括板柱、板件组和锚杆组件,其中,板件组包括自上而下的上板和下板件,下板件包括两个独立设置的下板,其中,锚杆组件包括第一锚杆和第二锚杆,板柱与上板通过第一锚杆固接,上板与两个下板分别通过第二锚杆固接,上板的上表面和/或下表面设置有第一配筋,下板的上表面和/或下表面设置有第二配筋；下板的设计方法包括：步骤1：采用剪切法抗拔计算确定下板尺寸和埋深；步骤2：对下板进行抗冲切验算,根据下板的尺寸、埋深和抗冲验结果确定下板的所述配筋的数据。本发明可以消除现场钢筋绑扎作业,同时降低了施工周期。(The invention discloses a kind of design methods of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem, double anchor slab bases fixed structure includes sheet-pile, plate group and anchor rod component, wherein, plate group includes top-down upper plate and lower plate, lower plate includes two lower plates being independently arranged, wherein, anchor rod component includes the first anchor pole and the second anchor pole, sheet-pile is affixed by the first anchor pole with upper plate, it is affixed that upper plate with two lower plates passes through the second anchor pole respectively, the upper surface and/or lower surface of upper plate are provided with the first arrangement of reinforcement, the upper surface and/or lower surface of lower plate are provided with the second arrangement of reinforcement；The design method of lower plate includes: step 1: being calculated using shearing method resistance to plucking and determines lower board size and buried depth；Step 2: Punching Shear checking computations being carried out to lower plate, the data that result determines the arrangement of reinforcement of lower plate are tested according to the size of lower plate, buried depth and anti-impact.The present invention can eliminate live reinforcing bar binding operation, while reduce construction period.)

1. the design method that transmission line of electricity combines the lower plate of the double anchor slab foundation structures of plate stem, which is characterized in that

Double anchor slab bases fixed structure includes sheet-pile, plate group and anchor rod component,

Wherein, the plate group includes top-down upper plate (1) and lower plate, and the lower plate includes two and is independently arranged Lower plate (2), and

Construct complete in the state of, the upper plate (1) and the lower plate (2) are embedded in underground, at least the one of the sheet-pile Part is exposed to environment；

Wherein, the anchor rod component includes the first anchor pole (5) and the second anchor pole (6), and the sheet-pile and upper plate (1) pass through the first anchor Bar (5) is affixed, and the upper plate (1) and two lower plates (2) are affixed by the second anchor pole (6) respectively, the upper surface of the upper plate (1) And/or lower surface is provided with the first arrangement of reinforcement, the upper surface and/or lower surface of the lower plate (2) are provided with the second arrangement of reinforcement；

The design method of the lower plate includes:

Step 1: being calculated using shearing method resistance to plucking and determine lower board size and buried depth；

Step 2: Punching Shear checking computations being carried out to lower plate, size, buried depth and the anti-impact of the lower plate determined according to step 1 test result Determine the data of the arrangement of reinforcement of the lower plate.

2. the design method of lower plate according to claim 1, which is characterized in that step 1 specifically includes:

Step 11, using shearing method carry out lower plate on pull out stability Calculation,

Step 12 obtains critical buried-depth according to pulling out stability Calculation in lower plate；

Step 13, the buried depth for determining the lower plate by the critical buried-depth according to following condition:

The buried depth of the lower plate is not more than the critical buried-depth.

3. the design method of lower plate according to claim 2, which is characterized in that the step 11 is specifically, using as follows Formula (1) carry out lower plate on pull out stability Calculation:

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

Wherein, γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor pole, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_V For resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For upper plate Self weight, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

4. the design method of lower plate according to claim 3, which is characterized in that the resistance to plucking soil body circular sliding surface shearing Resistance upright projection component T_VCalculation formula are as follows:

Wherein, wherein A₁、A₂For Dimensionless Calculation parameter, by the sliding surface form of the resistance to plucking soil body,It is true with embedded depth of foundation ratio λ It is fixed.

5. the design method of lower plate according to claim 3, which is characterized in that soil body self weight G in the circular sliding surface_S Formula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

Wherein, γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃For zero dimension Calculating parameter and sliding surface form, internal friction angle by the resistance to plucking soil bodyIt is determined with embedded depth of foundation λ ratio.

6. the design method of lower plate according to claim 1, which is characterized in that in step 2, the Punching Shear of the lower plate Check formula are as follows:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

Wherein, β_hpFor by punching bearing capacity influential factor of sectional height, f_tFor concrete tensile strength, a_sFor protective layer thickness.

7. the design method of lower plate according to claim 1, which is characterized in that in step 2, the data of the arrangement of reinforcement include The moment of flexure of reinforcing bar calculates the moment of flexure of reinforcing bar by following formula (5):

Wherein, b, b ' are the diameter of steel area, and B is the diameter of basic lower plate, and P is pressure.

8. in step 2, the data of the arrangement of reinforcement include the sectional area of reinforcing bar, both direction is calculated by following formula (6) By the sectional area of tension reinforcement:

The steel bar arrangement in the lower plate is carried out according to the sectional area of the reinforcing bar and design specification.

9. the design method of lower plate according to claim 1, which is characterized in that the lower plate is cast-in-situ steel reinforced concrete knot Structure.

10. the design method of lower plate according to claim 1, which is characterized in that the arrangement of reinforcement of the steel bar stress of the lower plate Rate is not less than 0.15%.

Technical field

The invention belongs to electric power line pole tower equipment technical fields, and in particular to a kind of double anchor slabs of transmission line of electricity joint plate stem The design method of the lower plate of foundation structure.

Background technique

Transmission line tower foundation mainly uses " heavy excavation " foundation class, " draw and dig base expanding and base expanding " foundation class, " explosion expanded piling " basis Class.The key dimension of " heavy excavation " foundation class need to be determined according to the resistance to plucking stability requirement of transmission line tower foundation, in order to full The needs of stability are pulled out on foot, it is necessary to increase key dimension, improve foundation cost, simultaneously because spoir is more, to environment It destroys also larger." draw and dig base expanding and base expanding " foundation class is suitable in the anhydrous cohesive soil for penetrating into foundation pit, while pile foundation specification provides, such as Basis uses pile foundation, and essential bearing stratum needs guiding through collapsible loess, therefore the basis is with not being suitable for big thickness collapsible loess Area." explosion expanded piling " foundation class difficulty of construction is larger, has biggish concealment, and complicated construction technique, construction quality are difficult to control It makes, construction quality problem is difficult to find in time, and there is also certain difficulties for detection after work.Therefore, in conclusion current transmission of electricity Inconvenient ask is detected after overhead line structures foundation structure is primarily present complicated construction technique, and construction quality is not easy to control and work Topic.

Summary of the invention

The object of the present invention is to provide the design methods of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem, it is intended to The existing complicated construction technique of the current double anchor slab foundation structures of transmission line of electricity joint plate stem is solved, and construction quality is not easily-controllable The problem of at least part in inconvenience is detected after system and work.

The technical scheme adopted by the invention is that

1, a kind of design method of the lower plate of the double anchor slab basis fixed structures of transmission line of electricity joint plate stem,

Double anchor slab bases fixed structure includes sheet-pile, plate group and anchor rod component,

Wherein, plate group includes top-down upper plate and lower plate, and lower plate includes two lower plates being independently arranged, and And

In the state of constructing completion, upper plate and lower plate are embedded in underground, and at least part of sheet-pile is exposed to environment；

Wherein, anchor rod component includes the first anchor pole and the second anchor pole, and sheet-pile and upper plate are affixed by the first anchor pole, upper plate and Two lower plates pass through that the second anchor pole is affixed respectively, and the upper surface and/or lower surface of upper plate are provided with the first arrangement of reinforcement, the upper table of lower plate Face and/or lower surface are provided with the second arrangement of reinforcement；

The design method of lower plate includes:

Step 1: being calculated using shearing method resistance to plucking and determine lower board size and buried depth；

Step 2: Punching Shear checking computations being carried out to lower plate, size, buried depth and the anti-impact of the lower plate determined according to step 1 test result Determine the data of the arrangement of reinforcement of lower plate.

The features of the present invention also characterized in that

Step 1 specifically includes:

Step 11, using shearing method carry out lower plate on pull out stability Calculation,

Step 12 obtains critical buried-depth according to pulling out stability Calculation in lower plate；

Step 13, the buried depth for determining lower plate by the critical buried-depth according to following condition:

The buried depth of lower plate is not more than critical buried-depth.

Step 11 is specifically, using stability Calculation is pulled out in following formula (1) progress lower plate:

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

Wherein, γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor cable, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For The self weight of upper plate, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

Resistance to plucking soil body circular sliding surface shearing resistance upright projection component T_VCalculation formula are as follows:

Wherein, wherein A₁、A₂For Dimensionless Calculation parameter, by the sliding surface form of the resistance to plucking soil body,With embedded depth of foundation ratio λ It determines.

Soil body self weight G in circular sliding surface_SFormula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

Wherein, γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃For nothing Dimension calculating parameter and sliding surface form, internal friction angle by the resistance to plucking soil bodyIt is determined with embedded depth of foundation λ ratio.

In step 2, the Punching Shear check formula of lower plate are as follows:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

Wherein, β_hpFor by punching bearing capacity influential factor of sectional height, f_tFor concrete tensile strength, a_sTo protect thickness Degree.

In step 2, the data of arrangement of reinforcement include the moment of flexure of reinforcing bar, and the moment of flexure of reinforcing bar is calculated by following formula (5):

Lower plate is monolithic reinforced concrete structure.

The ratio of reinforcement of the steel bar stress of lower plate is not less than 0.15%.

The beneficial effects of the present invention are: the design side of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention Method, the structure reinforcing bars can weld together with lower plate steel plate, and concreting is carried out after foundation bottom, can eliminate scene Reinforcing bar binds operation, while reducing construction period.

Detailed description of the invention

Fig. 1 is that joint plate stem is double in the design method of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention The schematic diagram of anchor slab foundation structure；

Fig. 2 is foundation structure in the design method of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention Schematic top plan view；

Fig. 3 is lower plate structure in the design method of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention Schematic diagram；

Fig. 4 is joint plate hitch in the design method of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention The schematic diagram of structure；

Fig. 5 is that lower plate stress is shown in the design method of the double anchor slab foundation structure lower plates of transmission line of electricity of the present invention joint plate stem It is intended to；

It Fig. 6, is that lower plate is pressurized in the design method for the lower plate that transmission line of electricity of the present invention combines the double anchor slab foundation structures of plate stem When moment of flexure Strength co-mputation simplified schematic diagram.

In figure, 1. upper plates, 2. lower plates, 3. upper plate steel plates, 4. lower plate steel plates, 5. first anchor poles, 6. second anchor poles, 7. lower spiral shells Cap, 8. protective caps, 9. gaskets, 10. upper plate short columns, 11. anchor poles, 12. anchor cables.

Specific embodiment

The following describes the present invention in detail with reference to the accompanying drawings and specific embodiments.

A kind of design method of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention,

As shown in Figure 1, Figure 2 and Figure 3, a kind of double anchor slab foundation structures of transmission line of electricity joint plate stem include sheet-pile 5, plate group And anchor rod component,

Wherein, plate group includes top-down upper plate 1 and lower plate, and lower plate includes two lower plates being independently arranged 2, And

In the state of constructing completion, upper plate 1 and lower plate 2 are embedded in underground, and at least part of sheet-pile 5 is exposed to ring Border；

Wherein, anchor rod component includes the first anchor pole 3 and the second anchor pole 4, and sheet-pile 5 is affixed by the first anchor pole 3 with upper plate 1, Upper plate 1 is affixed by the second anchor pole 4 respectively with two lower plates 2, and the upper surface and/or lower surface of upper plate 1 are provided with the first arrangement of reinforcement, The upper surface and/or lower surface of lower plate 2 are provided with the second arrangement of reinforcement；

A kind of design method of the lower plate of the double anchor slab foundation structures of transmission line of electricity joint plate stem of the present invention, comprising:

Step 1: being calculated using shearing method resistance to plucking and determine lower board size and buried depth；

Step 2: Punching Shear checking computations being carried out to lower plate, size, buried depth and the anti-impact of the lower plate determined according to step 1 are tested As a result the data of the arrangement of reinforcement of the lower plate are determined.

Wherein,

Step 1 specifically includes:

Step 11, using shearing method carry out lower plate on pull out stability Calculation,

Step 12 obtains critical buried-depth according to pulling out stability Calculation in lower plate；

Step 13, the buried depth for determining lower plate by the critical buried-depth according to following condition:

The buried depth of lower plate is not more than critical buried-depth.

Step 11 is specifically, using stability Calculation is pulled out in following formula (1) progress lower plate:

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

Wherein, γ_fAbove to pull out partial safety factor, T ' is the pulling force on every anchor cable, R_upFor basic Ultimate Up-lift Bearing Capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component, G_SIt is self-possessed for the soil body in circular sliding surface, G_{On f}For The self weight of upper plate, G_{Under f}For the self weight of lower plate, G_BackfillFor backfill weight.

Resistance to plucking soil body circular sliding surface shearing resistance upright projection component T_VCalculation formula are as follows:

Wherein, wherein A₁、A₂For Dimensionless Calculation parameter, by the sliding surface form of the resistance to plucking soil body,With embedded depth of foundation ratio λ It determines.

Soil body self weight G in circular sliding surface_SFormula are as follows:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

Wherein, γ_SFor the natural unit weight (kN/m of the resistance to plucking soil body³), V₀For h_tBasis volume (m in depth bounds³), A₃For nothing Dimension calculating parameter and sliding surface form, internal friction angle by the resistance to plucking soil bodyIt is determined with embedded depth of foundation λ ratio.

In step 2, the Punching Shear check formula of lower plate are as follows:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

Wherein, β_hpFor by punching bearing capacity influential factor of sectional height, f_tFor concrete tensile strength, a_sTo protect thickness Degree.

In step 2, the data of arrangement of reinforcement include the moment of flexure of reinforcing bar, and the moment of flexure of reinforcing bar is calculated by following formula (5):

Lower plate is monolithic reinforced concrete structure.

The ratio of reinforcement of the steel bar stress of lower plate is not less than 0.15%.

A kind of design method of the lower plate of the double anchor slab foundation structures of present invention transmission line of electricity joint plate stem is carried out below detailed It describes in detail bright.

1, shearing method resistance to plucking, which calculates, determines lower board size and buried depth,

As shown in figure 4, due to the presence of horizontal force, on the basis of pull out when, anchor cable can provide certain anti-for basic upper plate The power toppled, the pulling force on every anchor cable are as follows: T '

The lower plate on joint plate rope basis is calculated using shearing method pulls out stabilization, due to plate rope commbined foundations special shape and In view of the difficulty and economy of construction, lower plate should shallow embedding as far as possible, i.e. lower plate buried depth is not more than critical buried-depth.

Therefore only exist h_t≤h_cThe case where, then according to specification " DL/T 5219-2005 aerial power transmission line basic engineering skill Art regulation " it is calculated with shearing method when pulling out stable and should carry out pulling out stability Calculation using following formula.

γ_fT′≤R_up=T_V+G_S+G_{On f}+G_{Under f}+G_Backfill(1),

In formula (1):

γ_fAbove to pull out partial safety factor, can be chosen by table 1, T ' is that the pulling force on every anchor cable is R_upFor basic limit resistance to plucking Bearing capacity (KN), T_VFor resistance to plucking soil body circular sliding surface shearing resistance upright projection component；G_SCertainly for the soil body in circular sliding surface Weight；G_{On f}For the self weight of upper plate, G_{Under f}For the self weight of lower plate；G_BackfillFor backfill weight.

Table 1: on the basis of additional partial safety factor when pulling out

Resistance to plucking soil body circular sliding surface shearing resistance upright projection component is calculated according to the following formula:

In formula: A₁、A₂--- Dimensionless Calculation parameter, by the sliding surface form of the resistance to plucking soil body,It is true with embedded depth of foundation ratio λ It is fixed.

Wherein: α be intermediate computations parameter, indicate radius r with basic aspect ratio, λ (h/D) and change feature；

Wherein: n is resistance to plucking soil mass sliding surface morphological parameters, different with the physico mechanical characteristic variation of the soil body, can be according to examination Determination is tested, clay preferably takes n=4, and sandy soil preferably takes n=2~3, and Gobi desert rubble local product takes n=1.0~1.5.

Soil body self weight G in circular sliding surface_SIt is calculated according to the following formula:

G_S=μ γ_S(A₃h_t ³-V₀) (3),

Wherein: μ is earth resistance item reduction coefficient, γ_SFor resistance to plucking soil body natural unit weight (kN/m³), V₀For h_tIn depth bounds Basis volume (m³), A₃For Dimensionless Calculation parameter, by sliding surface form, the internal friction angle of the resistance to plucking soil bodyWith embedded depth of foundation ratio It determines.

Earth resistance item reduction coefficient calculation method is as follows:

1. as L >=D+2 λ h₁When, μ=1.00；

2. as L=D,

If h_tWhen≤2.5D, μ=0.75；

If 2.5D≤h_tWhen≤3.0D, μ=0.65；

If 3.0D≤h_tWhen≤4.0D, μ=0.55；

3. as D < L < D+2 λ h₁When, μ can be determined according to interpolation method；

In above formula, λ is related coefficient with adjacent resistance to plucking soil body shear force face,When, λ=0.50；When, λ=0.55；When, λ=0.60；When, λ=0.65；Other values can be obtained by interpolation It arrives.

G in formula 1_{On f}、G_{Under f}、G_BackfillIt is calculated as follows respectively:

G_{On f}=γ_ConcreteV_{Upper plate} (302)

G_{Under f}=γ_ConcreteV_{Lower plate} (303)

G_Backfill=γ_Backfillπr_Hole ²h_t (304)

In formula: γ_ConcreteFor concrete density (kN/m³)；V_{Upper plate}For upper plate volume (m³)；V_{Lower plate}For lower plate volume (m³)；γ_BackfillFor Backfill bulk density can be reduced natural rock-filled bulk density according to backfill coefficient, it is proposed that take 0.8 γ_S(kN/m³)；r_HoleFor lower plate hole Diameter (m).

Power transmission tower is corner tower, γ_fIt can be taken as 1.6 according to table 1, uplift force T '=556kN that lower plate is subject to.

Wherein A₁、A₂And A₃Value mainly by buried depth ratio h_t/ B control, therefore, the case where design can be according to different buried depth ratio Design the size and arrangement of reinforcement of lower plate, and carry out lower plate on pull out Stability Checking Calculation.

The critical depth of 2 various soil mass of table

Be enumerated the critical depth of different soil in table 2, when geological conditions is cohesive soil, critical depth between 3.5D~ Between 1.5D, therefore, when according to different buried depth than design lower plate, to make lower plate meet the requirement of shallow embedding, when design, is selected Buried depth ratio should be less than defined critical buried-depth ratio.It is contemplated that the dosage and buried depth of basic material are to the shadow of soil body resistance to plucking Ring, the size of lower plate again cannot excessive and buried depth also should not it is too small, this just determines that buried depth ratio cannot be too small.

Because being designed as the design on single basis, do not consider by horizontal force and adjacent foundation to power transmission tower upper and low approximations Reduction, since lower plate carries out angle θ=90 °, then it is 1.0 that lower plate, which allows upper and low approximations reduction factor,.

Allow upper and low approximations R_up:

γfT′<R_up(305),

Therefore the size of lower plate meets upper and low approximations requirement.

2, basic lower plate Punching Shear checking computations；

The lower plate stress on joint plate rope basis is as shown in figure 5, lower plate stress is axial tension, but is individually directed to lower plate When consideration, lower plate actual force is to act on lower plate bottom direction to upward pressure in fact, and size is T '.

The Punching Shear of lower plate is checked according to specification " DL/T 5219-2005 aerial power transmission line basic engineering technical stipulation " Following formula is calculated:

F_l≤0.7β_hpf_ta_m(h-a_s) (4),

In formula: β_hpAs h≤0.8m, to take 1.0 by punching bearing capacity influential factor of sectional height, as h >=2.0m, take 0.9, it is taken therebetween by linear interpolation, f_tFor concrete tensile strength, C35 concrete, f are generally used_tTake 1.57N/mm²； a_sFor protective layer thickness, 50mm is taken.

a_mIt is calculated according to following formula:

In formula: a_bFor punching failure cone least favorable side side length.

F_lIt is calculated according to following formula:

F_l=pA_l (402)

In formula: p is that lower plate is averaged net pressure (kN/m²), A_lFor Punching Shear shaded area (m²)。

Wherein the lower plate net pressure design value p that is averaged is calculated according to following formula:

In formula: r_{Lower plate}For lower plate radius (m)；

Punching Shear shaded area A_lIt is calculated according to following formula:

A_l=π [r_{Lower plate} ²-(0.45+h-0.05)²] (404),

According to the size being calculated, the diameter of lower plate is B, the thickness h of lower plate, can be in the hope of:

F_l≤0.7β_hpf_ta_m(h-a_s) (405),

Meet the requirement of basic Punching Shear.

3, lower plate Reinforcement Design；

Lower plate arrangement of reinforcement is calculated according to the buried depth and base plate size that are calculated.

Load that power transmission tower basis lower plate is subject to is axial load, as shown in fig. 6, and above upper plate calculation of Bending Moment Method, since bottom plate is circle, therefore the moment of flexure of lower plate top surface both direction can size it is identical, and can be according to " DL/T 5219- 2005 aerial power transmission line basic engineering technical stipulations " in following formula Conservative estimation.

In formula: b, b ' can be determined according in above and Fig. 6.

After obtaining moment of flexure, the tension reinforcement sectional area of both direction can be calculated according to the following formula:

It, need to be according to calculated reinforcing steel area and " GB50007- after calculating basic upper plate tension reinforcement area of section 2011 Code for design of building " in about baseplate reinforcing bar arrangement technical stipulation carry out power transmission tower joint plate rope basis The steel bar arrangement of upper plate.

(1) the steel bar stress minimum steel ratio of lower plate is no less than 0.15%, and the minimum diameter of lower plate steel bar stress is unsuitable Less than 10mm, spacing is not preferably greater than 200mm, is not also preferably less than 100mm.The thickness of cover to reinforcement takes 50mm；

(2) as diameter B >=2.5m of lower plate, the length of lower plate steel bar stress can use 0.9 times of radius, along radial direction Arrangement；

(3) when reinforcing bar demand is less than the demand of distributing bar, joint plate rope should be generally carried out according to constructional reinforcement The arrangement of reinforcement of the lower plate on basis.