CN116341089A - Method for calculating axial allowable bearing capacity of single pile of railway bored friction pile foundation - Google Patents
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Abstract
The invention relates to a method for calculating the axial allowable bearing capacity of a single pile of a railway drilling bored friction pile foundation, which comprises the following steps: calculating the calculated length l of the pile body p The method comprises the steps of carrying out a first treatment on the surface of the Calculating a pile body stability coefficient phi; calculating the final concrete center compression strength [ sigma ] c ]The method comprises the steps of carrying out a first treatment on the surface of the Calculating axial allowable bearing capacity P of single pile according to pile body material strength 1 The method comprises the steps of carrying out a first treatment on the surface of the Calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 The method comprises the steps of carrying out a first treatment on the surface of the Calculating the axial allowable bearing capacity [ P ] of single pile]When P 1 <P 2 When [ P ]]=P 1 The method comprises the steps of carrying out a first treatment on the surface of the Otherwise [ P ]]=P 2 . The invention can aim at the field of pile foundationsThe method solves the problem of inaccurate judgment by means of manual experience, ensures the safety of pile foundation design, and avoids unnecessary waste during engineering design.
Description
Technical Field
The invention relates to the technical field of pile foundations, in particular to a method for calculating an axial allowable bearing capacity of a single pile of a railway drilling bored friction pile foundation.
Background
When calculating the axial allowable bearing capacity of a single pile, a designer often relies on experience to determine some calculation parameters due to the vague simple guiding principle, for example, the allowable bearing capacity of the single pile is only improved according to the geological condition of the pile bottom or the bearing platform bottom, the main bearing capacity of the friction pile is provided by means of side friction resistance, the end resistance is small, and the actual condition cannot be reflected due to the improvement of the geological condition of the pile bottom or the bearing platform bottom. In addition, the allowable strength of the pile material has no quantitative calculation formula, 4000kN, 6000kN and 8000kN are respectively taken as the maximum bearing capacity of the pile according to the pile diameters of 1m, 1.25m and 1.5m by default, the actual situation cannot be considered by the numerical value, and the deviation is large.
Disclosure of Invention
The invention aims to solve the defects of the prior art and normalize the design flow of pile foundations, and provides a method for calculating the axial allowable bearing capacity of a single pile of a railway bored friction pile foundation.
The invention adopts the following technical scheme to realize the aim:
the method for calculating the axial allowable bearing capacity of the single pile of the railway bored friction pile foundation comprises the following steps:
s1, calculating calculated length l of pile body p ；
S2, determining a pile body stability coefficient phi;
s3, calculating the initial concrete center compression strength [ sigma ] according to the concrete strength grade c0 ]And the final concrete center compressive strength [ sigma ] is obtained by improving according to the load type c ]；
S4, calculating axial allowable bearing capacity P of single pile according to pile body material strength 1 ；
S5, calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 And according to the load type and the geological condition, P is compared with 2 Carrying out improvement;
s6, calculating the axial allowable bearing capacity [ P ] of the single pile]When P 1 <P 2 When [ P ]]=P 1 The method comprises the steps of carrying out a first treatment on the surface of the Otherwise [ P ]]=P 2 。
In step S1, the pile body is calculated to be of length l p Calculated as follows:
wherein:
l 0 pile length from the bottom of the bearing platform to the ground, m;
h, pile length of the part below the ground, m;
deformation coefficient of a-pile foundation.
In step S2, pile body stability factor phi is according to l p D is the diameter of pile foundation and m; the method comprises the following steps:
when l p When/d is less than or equal to 7, phi=1.00;
when 7 < l p Phi=1.00+ (0.98-1.00)/(8.5-7) × (l) when/d is less than or equal to 8.5 p /d-7)；
When 8.5 < l p When/d is less than or equal to 10.5, phi=0.98+ (0.95-0.98)/(10.5-8.5) × (l) p /d-8.5)；
When 10.5 < l p Phi=0.95+ (0.92-0.95)/(12-10.5) x (l) when/d is not more than 12 p /d-10.5)；
When 12 < l p Phi=0.92+ (0.87-0.92)/(14-12) × (l) when/d is not more than 14 p /d-12)；
When 14 < l p Phi=0.87+ (0.81-0.87)/(15.5-14) × (l) when/d is not more than 15.5 p /d-14)；
When 15.5 < l p When/d is less than or equal to 17, phi=0.81+ (0.75-0.81)/(17-15.5) × (l) p /d-15.5)；
When 17 < l p Phi=0.75+ (0.70-0.75)/(19-17) × (l) when/d is less than or equal to 19 p /d-17)；
When 19 < l p Phi=0.70+ (0.65-0.70)/(21-19) × (l) when/d is not more than 21 p /d-19)；
When 21 < l p Phi=0.65+ (0.60-0.65)/(22.5-21) × (l) when/d is not more than 22.5 p /d-21)；
When 22.5 < l p When/d is less than or equal to 24, phi=0.60+ (0.56-0.60)/(24-22.5) × (l) p /d-22.5)；
When 24 < l p When/d is less than or equal to 26, phi=0.56+ (0.52-0.56)/(26-24) × (l) p /d-24)；
When l p When/d is equal to or greater than 26, phi=0.52.
In step S3, the initial concrete center compression strength [ sigma ] is calculated according to the concrete strength grade c0 ]The method specifically comprises the following steps:
when the concrete strength is C25, [ sigma ] c0 ]=6.8MPa；
When the concrete strength is C30, [ sigma ] c0 ]=8.0MPa；
When the concrete strength is C35, [ sigma ] c0 ]=9.4MPa；
When the concrete strength is C40, [ sigma ] c0 ]=10.8MPa；
When the concrete strength is C45, [ sigma ] c0 ]=12.0MPa；
[ Sigma ] when the concrete strength is C50 c0 ]=13.4MPa；
When the concrete strength is C55, [ sigma ] c0 ]=14.8MPa；
When the concrete strength is C60, [ sigma ] c0 ]=16.0MPa。
In step S3, an improvement coefficient is determined according to the load type, and the final concrete center compressive strength [ sigma ] is obtained according to the improvement coefficient c ]；
When the load type is the main force, [ sigma ] c ]=[σ c0 ]；
When the load type is main force plus additional force, [ sigma ] c ]=1.3×[σ c0 ]；
When the load type is main force plus special force, [ sigma ] c ]=1.5×[σ c0 ]；
When the load type is principal force+earthquake force, [ sigma ] c ]=1.5×[σ c0 ]。
In step S4, calculating the axial allowable bearing capacity P of the single pile according to the pile body material strength 1 The calculation formula is as follows:
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )；
wherein:
a-pile body area, m 2 ；
The ratio of the elastic modulus of the n-bar to the deformation modulus of the concrete;
ρ 0 -minimum pile body reinforcement.
In step S4, the ratio n of the elastic modulus of the reinforcing steel bar to the deformation modulus of the concrete is determined according to the strength grade of the concrete, specifically:
when the concrete strength is C25, C30, C35, n=10;
when the concrete strength is C40, C45, C50, C55, C60, n=8.
In step S4, the minimum reinforcement ratio ρ of the pile body 0 The method is determined according to the types of the steel bars, and specifically comprises the following steps:
when the type of the reinforcing steel bar is HPB300, ρ 0 =0.55%；
When the type of the reinforcing steel bar is HPB400, ρ 0 =0.50%；
When the type of the reinforcing steel bar is HPB500, ρ 0 =0.45%。
In step S5, calculating the axial allowable bearing capacity P of the single pile according to the rock-soil resistance 2 The calculation formula is as follows:
P 2 =Σq i F i +q 0 N 0 ；
wherein:
F i -the side friction of each layer of soil;
N 0 -end resistance of the pile bottom;
q i 、q 0 -foundation allowable bearing capacity increase factor, including soil providing side friction resistance and soil providing end resistance.
In step S5, q i 、q 0 Depending on the load type and geological conditions, the following are specific:
p1, when the load type is dominant: q i 、q 0 1.0;
p2, when the load type is main force plus additional force: q i 、q 0 1.2;
p3, when the load type is main force+special force:
σ 0 is the basic bearing capacity of foundation soil,
when sigma is 0 >At 500KPa, q i 、q 0 1.4;
when 150KPa<σ 0 Q is less than or equal to 500KPa i 、q 0 1.3;
when sigma is 0 Q is less than or equal to 150KPa i 、q 0 1.2;
p4, when the load type is main force+earthquake force:
σ 0 is the basic bearing capacity of foundation soil,
when sigma is 0 >At 500KPa, q i 、q 0 1.4;
when 150KPa<σ 0 Q is less than or equal to 500KPa i 、q 0 1.3;
when sigma is 0 Q is less than or equal to 150KPa i 、q 0 1.2.
The beneficial effects of the invention are as follows: aiming at the problem of calculating the allowable bearing capacity of a single pile, the invention provides a single pile axial allowable bearing capacity calculation formula calculated according to the pile body material strength from the three aspects of pile body stability, concrete material strength and reinforcement ratio, and respectively improves the bearing capacities of side friction resistance and end resistance according to load types and geological conditions, thereby solving the problem of inaccurate judgment by means of manual experience, ensuring the safety of pile foundation design and avoiding unnecessary waste during engineering design. The method is suitable for the design of bored friction pile foundations of bridges such as roads, railways, municipal works and the like.
Drawings
FIG. 1 is a computational flow diagram of the present invention;
FIG. 2 is a schematic view of a friction pile foundation according to embodiment 1 of the present invention;
the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Detailed Description
The principles and features of the present invention are described below with reference to the drawings, the examples are illustrated for the purpose of illustrating the invention and are not to be construed as limiting the scope of the invention. The invention is more particularly described by way of example in the following paragraphs with reference to the drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When a component is considered to be "connected" to another component, it can be directly connected to the other component or intervening components may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
as shown in fig. 1, the method for calculating the axial allowable bearing capacity of the single pile of the railway bored friction pile foundation comprises the following steps:
s1, calculating calculated length l of pile body p ；
S2, determining a pile body stability coefficient phi;
s3, calculating the initial concrete center compression strength [ sigma ] according to the concrete strength grade c0 ]And the final concrete center compressive strength [ sigma ] is obtained by improving according to the load type c ]；
S4, calculating axial allowable bearing capacity P of single pile according to pile body material strength 1 ；
S5, calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 And according to the load type and the geological condition, P is compared with 2 Carrying out improvement;
s6, calculating the axial allowable bearing capacity [ P ] of the single pile]When P 1 <P 2 When [ P ]]=P 1 The method comprises the steps of carrying out a first treatment on the surface of the Otherwise [ P ]]=P 2 。
In step S1, the pile body is calculated to be of length l p Calculated as follows:
wherein:
l 0 pile length from the bottom of the bearing platform to the ground, m;
h, pile length of the part below the ground, m;
deformation coefficient of a-pile foundation.
In step S2, pile body stability coefficient Φ is calculated according to the vertical direction in table 1 by a linear difference formula:
table 1 pile body stability factor table
Note that: table l p Calculating the length, m, of the pile body; d is the diameter of pile foundation and m.
The method comprises the following steps:
when l p When/d is less than or equal to 7, phi=1.00;
when 7 < l p Phi=1.00+ (0.98-1.00)/(8.5-7) × (l) when/d is less than or equal to 8.5 p /d-7)；
When 8.5 < l p When/d is less than or equal to 10.5, phi=0.98+ (0.95-0.98)/(10.5-8.5) × (l) p /d-8.5)；
When 10.5 < l p Phi=0.95+ (0.92-0.95)/(12-10.5) x (l) when/d is not more than 12 p /d-10.5)；
When 12 < l p Phi=0.92+ (0.87-0.92)/(14-12) × (l) when/d is not more than 14 p /d-12)；
When 14 < l p Phi=0.87+ (0.81-0.87)/(15.5-14) × (l) when/d is not more than 15.5 p /d-14)；
When 15.5 < l p When/d is less than or equal to 17, phi=0.81+ (0.75-0.81)/(17-15.5) × (l) p /d-15.5)；
When 17 < l p Phi=0.75+ (0.70-0.75)/(19-17) × (l) when/d is less than or equal to 19 p /d-17)；
When 19 < l p Phi=0.70+ (0.65-0.70)/(21-19) × (l) when/d is not more than 21 p /d-19)；
When 21 < l p Phi=0.65+ (0.60-0.65)/(22.5-21) × (l) when/d is not more than 22.5 p /d-21)；
When 22.5 < l p When/d is less than or equal to 24, phi=0.60+ (0.56-0.60)/(24-22.5) × (l) p /d-22.5)；
When 24 < l p When/d is less than or equal to 26, phi=0.56+ (0.52-0.56)/(26-24) × (l) p /d-24)；
When l p When/d is equal to or greater than 26, phi=0.52.
In step S3, according to the concrete strength gradeCalculating the central compression strength [ sigma ] of initial concrete c0 ]Look-up is performed as in table 2.
Table 2 concrete center compressive Strength (MPa)
And according to the load type, the compressive strength [ sigma ] of the final concrete center is obtained by improving according to the table 3 c ]。
Table 3 table for coefficient of improvement in compressive strength of concrete center
In step S4, calculating the axial allowable bearing capacity P of the single pile according to the pile body material strength 1 The calculation formula is as follows:
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )；
wherein:
a-pile body area, m 2 ；
The ratio of the elastic modulus of the n-bar to the deformation modulus of the concrete;
ρ 0 -minimum pile body reinforcement.
The ratio of the elastic modulus of the steel bars to the deformation modulus of the concrete was determined according to the strength grade of the concrete, as shown in table 4.
TABLE 4 ratio of elastic modulus of reinforcing bars to deformation modulus of concrete
Minimum reinforcement rate ρ of pile body 0 Determined according to the kind of the reinforcing bars as shown in table 5.
Table 5 pile body minimum reinforcement ratio table
According to the resistance of rock and soilCalculating the axial allowable bearing capacity P of single pile 2 The calculation formula is as follows:
P 2 =Σq i F i +q 0 N 0 ；
wherein:
F i -the side friction of each layer of soil;
N 0 -end resistance of the pile bottom;
q i 、q 0 -foundation allowable bearing capacity increase factor, including soil providing side friction resistance and soil providing end resistance.
q i 、q 0 Depending on the type of load and the geological conditions, see in particular table 6.
Table 6 allowable bearing capacity improvement coefficient of foundation
Note that: sigma in table 0 Is the basic bearing capacity of foundation soil, KPa.
Specific example 1:
some bridge pier adopts a bored cast-in-place friction pile foundation, the diameter of a pile foundation is 1m, the number of piles is 8, the pile length is 36.5m, the ground elevation is 112.335m, the bearing platform bottom elevation is 115.335m, the deformation coefficient of the pile foundation is 0.3447, the pile body is concrete marked with C30, the steel bar adopts HPB300, other specific dimensions and geological conditions are shown in figure 2, and geological parameters are shown in table 7.
TABLE 7 geological parameter table
Pile length l of pile cap bottom to ground 0 =3m；
Pile length h=33.5m for the subsurface portion;
4/α=4/0.3447=11.60<h=33.5；
calculated length l of pile body p =0.5×(l0+4/α)=0.5×(3+11.60)=7.30；
l p D=7.30/1=7.30, looking up table 1, phi=1+ (0.98-1)/(8.5-7) ×(7.30-7)=0.996；
Table look-up 4 according to C30, n=10;
look-up table 5 according to HPB300, ρ 0 =0.55%；
Then, the axial allowable bearing capacity of the single pile is respectively calculated according to the following 4 load types:
(1) Load type: a main force;
look up table 2 according to C30 and consider the improvement factor of Table 3, [ sigma ] c ]=1.0×8=8Mpa；
Calculating the axial allowable bearing capacity P of a single pile calculated according to the pile body material strength 1 ；
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )=0.7×0.996×8000×π/4×(1+10×0.55%)=4621.57kN；
Calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 ；
Look-up table 6, q 1 =1.0，q 2 =1.0，q 3 =1.0，q 4 =1.0，q 5 =1.0，q 0 =1.0；
P 2 =Σq i F i +q 0 N 0 =1.0×371.50+1.0×251.94+1.0×1583.37+1.0×502.66+1.0×589.05+1.0×203.29=3501.61kN；
Therefore, under the working condition of main force, the single pile axially tolerates the bearing capacity [ P ]]=min{P 1 ，P 2 }={4621.57，3941.08}=3501.61kN。
(2) Load type: main force + additional force;
look up table 2 according to C30 and consider the improvement factor of Table 3, [ sigma ] c ]=1.3×8=10.4Mpa；
Calculating the axial allowable bearing capacity P of a single pile calculated according to the pile body material strength 1 ；
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )=0.7×0.996×10400×π/4×(1+10×0.55%)=6008.04kN；
Calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 ；
Look-up table 6, q 1 =1.2，q 2 =1.2，q 3 =1.2，q 4 =1.2，q 5 =1.2，q 0 =1.2；
P 2 =Σq i F i +q 0 N 0 =1.2×371.50+1.2×251.94+1.2×1583.37+1.2×502.66+1.2×589.05+1.2×203.29=4201.93kN；
Therefore, under the working condition of main force and additional force, the single pile axially tolerates the bearing force [ P ]]=min{P 1 ，P 2 }={6008.04，4201.93}=4201.93kN；
(3) Load type: main force + special force;
look up table 2 according to C30 and consider the improvement factor of Table 3, [ sigma ] c ]=1.5×8=12.0Mpa；
Calculating the axial allowable bearing capacity P of a single pile calculated according to the pile body material strength 1 ；
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )=0.7×0.996×12000×π/4×(1+10×0.55%)=6932.36kN；
Calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 ；
P 2 =Σq i F i +q 0 N 0 =1.2×371.50+1.3×251.94+1.3×1583.37+1.3×502.66+1.4×589.05+1.4×203.29=4594.44kN；
Therefore, under the working condition of main force and special force, the single pile axially tolerates the bearing force [ P ]]=min{P 1 ，P 2 }={6932.36，4594.44}=4594.44kN；
(4) Load type: main force + earthquake force;
look up table 2 according to C30 and consider the improvement factor of Table 3, [ sigma ] c ]=1.5×8=12.0Mpa；
Calculating the axial allowable bearing capacity P of a single pile calculated according to the pile body material strength 1 ；
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )=0.7×0.996×12000×π/4×(1+10×0.55%)=6932.36kN；
Calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 ；
P 2 =Σq i F i +q 0 N 0 =1.2×371.50+1.3×251.94+1.3×1583.37+1.3×502.66+1.4×589.05+1.4×203.29=4594.44kN；
Therefore, under the working condition of main force and earthquake force, the single pile axially tolerates the bearing force [ P ]]=min{P 1 ，P 2 }={6932.36，4594.44}=4594.44kN。
Aiming at the problem of calculating the allowable bearing capacity of a single pile, the invention provides a single pile axial allowable bearing capacity calculation formula calculated according to the pile body material strength from the three aspects of pile body stability, concrete material strength and reinforcement ratio, and respectively improves the bearing capacities of side friction resistance and end resistance according to load types and geological conditions, thereby solving the problem of inaccurate judgment by means of manual experience, ensuring the safety of pile foundation design and avoiding unnecessary waste during engineering design. The method is suitable for the design of bored friction pile foundations of bridges such as roads, railways, municipal works and the like.
While the invention has been described above with reference to the accompanying drawings, it will be apparent that the invention is not limited to the above embodiments, but is intended to cover various modifications, either made by the method concepts and technical solutions of the invention, or applied directly to other applications without modification, within the scope of the invention.
Claims (10)
1. The method for calculating the axial allowable bearing capacity of the single pile of the railway bored friction pile foundation is characterized by comprising the following steps of:
s1, calculating calculated length l of pile body p ；
S2, determining a pile body stability coefficient phi;
s3, calculating the initial concrete center compression strength [ sigma ] according to the concrete strength grade c0 ]And the final concrete center compressive strength [ sigma ] is obtained by improving according to the load type c ]；
S4, calculating axial allowable bearing capacity P of single pile according to pile body material strength 1 ；
S5, calculating axial allowable bearing capacity P of single pile according to rock-soil resistance 2 And according to the load type and the geological condition, P is compared with 2 Carrying out improvement;
s6, calculating the axial allowable bearing capacity [ P ] of the single pile]When P 1 <P 2 When [ P ]]=P 1 The method comprises the steps of carrying out a first treatment on the surface of the Otherwise [ P ]]=P 2 。
2. The method for calculating axial allowable bearing capacity of a single pile of a bored friction pile foundation for railways according to claim 1, wherein in step S1, a pile body is calculated to have a length l p Calculated as follows:
wherein:
l 0 pile length from the bottom of the bearing platform to the ground, m;
h, pile length of the part below the ground, m;
deformation coefficient of a-pile foundation.
3. The method for calculating axial allowable bearing capacity of a single pile of a bored friction pile foundation for railways according to claim 2, wherein in step S2, the pile body stability factor Φ is determined according to l p D is the diameter of pile foundation and m; the method comprises the following steps:
when l p When/d is less than or equal to 7, phi=1.00;
when 7 < l p Phi=1.00+ (0.98-1.00)/(8.5-7) × (l) when/d is less than or equal to 8.5 p /d-7)；
When 8.5 < l p Phi=0.98+ (0.95-0.98)/. Times.d. is less than or equal to 10.510.5-8.5)×(l p /d-8.5)；
When 10.5 < l p Phi=0.95+ (0.92-0.95)/(12-10.5) x (l) when/d is not more than 12 p /d-10.5)；
When 12 < l p Phi=0.92+ (0.87-0.92)/(14-12) × (l) when/d is not more than 14 p /d-12)；
When 14 < l p Phi=0.87+ (0.81-0.87)/(15.5-14) × (l) when/d is not more than 15.5 p /d-14)；
When 15.5 < l p When/d is less than or equal to 17, phi=0.81+ (0.75-0.81)/(17-15.5) × (l) p /d-15.5)；
When 17 < l p Phi=0.75+ (0.70-0.75)/(19-17) × (l) when/d is less than or equal to 19 p /d-17)；
When 19 < l p Phi=0.70+ (0.65-0.70)/(21-19) × (l) when/d is not more than 21 p /d-19)；
When 21 < l p Phi=0.65+ (0.60-0.65)/(22.5-21) × (l) when/d is not more than 22.5 p /d-21)；
When 22.5 < l p When/d is less than or equal to 24, phi=0.60+ (0.56-0.60)/(24-22.5) × (l) p /d-22.5)；
When 24 < l p When/d is less than or equal to 26, phi=0.56+ (0.52-0.56)/(26-24) × (l) p /d-24)；
When l p When/d is equal to or greater than 26, phi=0.52.
4. The method for calculating axial allowable bearing capacity of a single pile of a bored friction pile foundation for railways according to claim 3, wherein in step S3, initial concrete center compression strength [ σ ] is calculated from the concrete strength level c0 ]The method specifically comprises the following steps:
when the concrete strength is C25, [ sigma ] c0 ]=6.8MPa；
When the concrete strength is C30, [ sigma ] c0 ]=8.0MPa；
When the concrete strength is C35, [ sigma ] c0 ]=9.4MPa；
When the concrete strength is C40, [ sigma ] c0 ]=10.8MPa；
When the concrete strength is C45, [ sigma ] c0 ]=12.0MPa；
[ Sigma ] when the concrete strength is C50 c0 ]=13.4MPa；
When the concrete strength is C55, [ sigma ] c0 ]=14.8MPa；
When the concrete strength is C60, [ sigma ] c0 ]=16.0MPa。
5. The method for calculating the axial allowable bearing capacity of a single pile of a railway bored friction pile foundation according to claim 4, wherein in step S3, an improvement coefficient is determined according to the load type, and the final concrete center compressive strength [ σ ] is obtained according to the improvement coefficient c ]；
When the load type is the main force, [ sigma ] c ]=[σ c0 ]；
When the load type is main force plus additional force, [ sigma ] c ]=1.3×[σ c0 ]；
When the load type is main force plus special force, [ sigma ] c ]=1.5×[σ c0 ]；
When the load type is principal force+earthquake force, [ sigma ] c ]=1.5×[σ c0 ]。
6. The method for calculating axial allowable bearing capacity of single pile of bored friction pile foundation for railway according to claim 5, wherein in step S4, the axial allowable bearing capacity P of single pile is calculated according to the pile body material strength 1 The calculation formula is as follows:
P 1 =0.7·φ·[σ c ]·A·(1+nρ 0 )；
wherein:
a-pile body area, m 2 ；
The ratio of the elastic modulus of the n-bar to the deformation modulus of the concrete;
ρ 0 -minimum pile body reinforcement.
7. The method for calculating the axial allowable bearing capacity of a single pile of a railway bored friction pile foundation according to claim 6, wherein in step S4, the ratio n of the elastic modulus of the reinforcing steel bar to the deformation modulus of the concrete is determined according to the concrete strength grade, specifically:
when the concrete strength is C25, C30, C35, n=10;
when the concrete strength is C40, C45, C50, C55, C60, n=8.
8. The method for calculating the axial allowable bearing capacity of a single pile of a railway bored friction pile foundation according to claim 7, wherein in step S4, the minimum reinforcement ratio ρ of the pile body is 0 The method is determined according to the types of the steel bars, and specifically comprises the following steps:
when the type of the reinforcing steel bar is HPB300, ρ 0 =0.55%；
When the type of the reinforcing steel bar is HPB400, ρ 0 =0.50%；
When the type of the reinforcing steel bar is HPB500, ρ 0 =0.45%。
9. The method for calculating the axial allowable bearing capacity of a single pile of a railway bored friction pile foundation according to claim 8, wherein in step S5, the axial allowable bearing capacity P of the single pile is calculated according to the geotechnical resistance 2 The calculation formula is as follows:
P 2 =Σq i F i +q 0 N 0 ；
wherein:
F i -the side friction of each layer of soil;
N 0 -end resistance of the pile bottom;
q i 、q 0 -foundation allowable bearing capacity increase factor, including soil providing side friction resistance and soil providing end resistance.
10. The method for calculating the axial allowable bearing capacity of a single pile of a bored friction pile foundation for railways according to claim 9, wherein in step S5, q i 、q 0 Depending on the load type and geological conditions, the following are specific:
p1, when the load type is dominant: q i 、q 0 1.0;
p2, when the load type is main force plus additional force: q i 、q 0 1.2;
p3, when the load type is main force+special force:
σ 0 is the basic bearing capacity of foundation soil,
when sigma is 0 >At 500KPa, q i 、q 0 1.4;
when 150KPa<σ 0 Q is less than or equal to 500KPa i 、q 0 1.3;
when sigma is 0 Q is less than or equal to 150KPa i 、q 0 1.2;
p4, when the load type is main force+earthquake force:
σ 0 is the basic bearing capacity of foundation soil,
when sigma is 0 >At 500KPa, q i 、q 0 1.4;
when 150KPa<σ 0 Q is less than or equal to 500KPa i 、q 0 1.3;
when sigma is 0 Q is less than or equal to 150KPa i 、q 0 1.2.
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Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103266634A (en) * | 2013-01-09 | 2013-08-28 | 交通运输部公路科学研究所 | Determination method of bearing capacity of overlong bored pile |
| CN103981861A (en) * | 2013-05-17 | 2014-08-13 | 林建省 | Pile foundation theory, lime soil pile carrying capacity and lime soil pile stirring impacting operation system |
| CN104863124A (en) * | 2015-05-11 | 2015-08-26 | 华南理工大学 | Device and method for utilizing bearing force of soil between cast-in-place piles |
| CN105926689A (en) * | 2016-05-18 | 2016-09-07 | 中铁上海设计院集团有限公司 | Calculation method for allowable single pile bearing capacity of following drilling method railway tubular piles |
| CN108222084A (en) * | 2018-01-12 | 2018-06-29 | 上海城乡建筑设计院有限公司 | A kind of Analysis of Bearing Capacity method of pile body under engineering pile test pile operating mode |
| CN108221972A (en) * | 2018-03-12 | 2018-06-29 | 四川省建筑科学研究院 | A kind of built pile and its construction method and vertical bearing capacity of single pile computational methods |
| CN112012198A (en) * | 2020-08-31 | 2020-12-01 | 中国建筑西北设计研究院有限公司 | Pile body variable concrete strength grade cast-in-place pile and strength grade determination method thereof |
| CN112329104A (en) * | 2020-11-05 | 2021-02-05 | 中国铁路设计集团有限公司 | Calculation method for rotary excavating squeezing and expanding cast-in-place pile |
| CN113051643A (en) * | 2021-03-17 | 2021-06-29 | 河北建设勘察研究院有限公司 | Method and system for calculating vertical ultimate bearing capacity of karst cave penetrating type rock-socketed pile |
| CN116070325A (en) * | 2023-02-13 | 2023-05-05 | 合肥工业大学 | Method for calculating horizontal bearing capacity of rigid pile attached with multilayer limited stiffness beams |
-
2023
- 2023-05-31 CN CN202310626212.XA patent/CN116341089B/en active Active
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103266634A (en) * | 2013-01-09 | 2013-08-28 | 交通运输部公路科学研究所 | Determination method of bearing capacity of overlong bored pile |
| CN103981861A (en) * | 2013-05-17 | 2014-08-13 | 林建省 | Pile foundation theory, lime soil pile carrying capacity and lime soil pile stirring impacting operation system |
| CN104863124A (en) * | 2015-05-11 | 2015-08-26 | 华南理工大学 | Device and method for utilizing bearing force of soil between cast-in-place piles |
| CN105926689A (en) * | 2016-05-18 | 2016-09-07 | 中铁上海设计院集团有限公司 | Calculation method for allowable single pile bearing capacity of following drilling method railway tubular piles |
| CN108222084A (en) * | 2018-01-12 | 2018-06-29 | 上海城乡建筑设计院有限公司 | A kind of Analysis of Bearing Capacity method of pile body under engineering pile test pile operating mode |
| CN108221972A (en) * | 2018-03-12 | 2018-06-29 | 四川省建筑科学研究院 | A kind of built pile and its construction method and vertical bearing capacity of single pile computational methods |
| CN112012198A (en) * | 2020-08-31 | 2020-12-01 | 中国建筑西北设计研究院有限公司 | Pile body variable concrete strength grade cast-in-place pile and strength grade determination method thereof |
| CN112329104A (en) * | 2020-11-05 | 2021-02-05 | 中国铁路设计集团有限公司 | Calculation method for rotary excavating squeezing and expanding cast-in-place pile |
| CN113051643A (en) * | 2021-03-17 | 2021-06-29 | 河北建设勘察研究院有限公司 | Method and system for calculating vertical ultimate bearing capacity of karst cave penetrating type rock-socketed pile |
| CN116070325A (en) * | 2023-02-13 | 2023-05-05 | 合肥工业大学 | Method for calculating horizontal bearing capacity of rigid pile attached with multilayer limited stiffness beams |
Non-Patent Citations (2)
| Title |
|---|
| QINGFU LI ET AL.: "Reliability Analysis of Bearing Capacity of Pile Foundation of Continuous Rigid Frame Bridge During Construction", 《IOP CONF. SERIES: MATERIALS SCIENCE AND ENGINEERING 780 (2020) 022024》, pages 1 - 9 * |
| 廖立坚 等: "铁路桥梁桩基优化计算方法研究", 《铁道工程学报》, no. 2, pages 47 - 52 * |
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