CN114004086A - Barrel-type foundation anti-overturning stability checking calculation method based on barrel-soil separation - Google Patents
Barrel-type foundation anti-overturning stability checking calculation method based on barrel-soil separation Download PDFInfo
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Abstract
The invention provides a barrel type foundation anti-overturning stability checking calculation method based on barrel soil separation, which comprises the following steps of: (1) building a barrel-type foundation anti-overturning bearing stress model with barrel-soil separation; (2) calculating the anti-overturning moment M of the cylinderRAnd an overturning moment Mq(ii) a (3) And calculating the minimum value of the anti-overturning safety coefficient and the corresponding position of the rotating shaft. The invention provides a method for checking and calculating the anti-overturning stability of a barrel-shaped foundation in a barrel wall bearing mode based on a stress model of the large-diameter wide and shallow barrel-shaped foundation which plays an anti-overturning role in barrel-soil separation and frictional resistance of inner and outer walls of a barrel. On the basis of analyzing a large amount of test data and numerical simulation results, the thought iteration trial calculation for obtaining the extreme value is adopted to find the most dangerous overturning rotating shaft of the cylindrical foundation to obtain a calculation method for the anti-overturning safety coefficient of the cylindrical foundation, so that the method can accurately evaluateThe anti-overturning stability of the offshore wind power large-diameter cylinder base under the extreme wind wave current load accords with the engineering practice, and the method is simple and clear.
Description
Technical Field
The invention belongs to the technical field of construction, and particularly relates to a barrel-type foundation anti-overturning stability checking calculation method based on barrel-soil separation.
Background
The cylindrical foundation can be prefabricated on the shore, towed by self-floating and sunk by suction, has the advantages of low manufacturing cost, convenience in transportation and installation, short field construction time and the like, and shows great development potential in offshore wind power engineering in recent years. Different from other ocean engineering, the offshore wind power engineering superstructure is high-rising, and environmental loads such as wind, wave, stream and the like acting on the superstructure generate huge overturning loads on the top surface of the foundation.
The large-diameter wide-shallow cylindrical foundation consists of a dome cover and a cylindrical skirt embedded into a seabed by a certain depth, under the action of overturning load, the cylindrical body and an internal soil body generate certain cooperative motion and relative motion, and the anti-overturning bearing mode of the large-diameter wide-shallow cylindrical foundation is different from that of a circular shallow foundation without a cylindrical skirt and a pier foundation with the same height-diameter ratio. Tests and finite element researches show that in a soil body with poor cohesiveness, the cooperative motion degree of the cylinder body and the internal soil body is low, and no corresponding theoretical method exists for the calculation of the anti-overturning stability under the cylinder-soil separation setting at present, so that a simplified method for the basic anti-overturning stability of the cylinder-soil separation calculation is needed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a barrel-type foundation anti-overturning stability checking method based on barrel-soil separation, which is mainly used for overcoming the defect that no corresponding theoretical method exists in the barrel-soil separation setting anti-overturning stability checking method in the prior art.
The invention provides a barrel type foundation anti-overturning stability checking calculation method based on barrel soil separation, which comprises the following steps of:
(1) anti-overturning bearing stress model for building barrel-soil separated barrel-shaped foundation
The model is established on the basis that the barrel and the soil body in the barrel can generate relative motion under the action of overturning load, and the inner side and the outer side of the wall surface of the barrel bear frictional resistance; under the action of overturning load, setting the foundation to rotate around a bottom surface rotating shaft mn;
(2) calculating the anti-overturning moment MR and the overturning moment Mq of the cylinder;
(3) calculating the minimum value of the anti-overturning safety coefficient and the corresponding position of the rotating shaft
The anti-overturning safety coefficient:
SFt＝MR/Mq (31)
to determine the most dangerous situation, the antidumping safety factor is derived from λ:
according to (32), the position of the foundation around the bottom surface rotating shaft mn is obtained through iterative trial calculation, and the minimum safety factor of the barrel-type foundation against overturning is calculated.
In some embodiments of the present invention, the,
the anti-overturning moment MRComprises the following steps:
MR＝MV+MR1+MEp+Mfs (1)
in the formula: mVThe anti-tilting moment is provided for vertical force and self weight; mR1The anti-overturning moment is provided for the foundation counterforce in the arc-shaped area of the cylinder end and the anti-overturning moment is provided for the foundation counterforce in the arc-shaped area of the cylinder top cover; mEpThe anti-overturning moment is provided for the passive soil pressure on the inner side and the outer side of the foundation; mfsThe anti-overturning moment is provided for the friction resistance of the inner side and the outer side of the foundation.
In some embodiments of the present invention, the,
the overturning moment MqComprises the following steps:
Mq＝MH+M0+MEa (20)
in the formula: mHOverturning moment generated by horizontal load; m0Moment load acting on the foundation; mEaIndicating the overturning moment generated by the active earth pressure outside the foundation.
In some embodiments, the respective section anti-overturning moments are calculated as follows:
a. anti-overturning moment provided by vertical load:
MV＝(QV+G)λR (10)
in the formula: qVIs a vertical load; g is the basis dead weight;
b. the anti-overturning moment that top cap and barrel end foundation counter-force provided:
Mx＝qu1Ax1lx1+qu2Ax2lx2 (11)
in the formula: q. q.su1、qu2The characteristic value of the bearing capacity of the foundation at the pressed positions of the top cover and the cylinder end can be determined by field tests such as load tests, static sounding and the like and formula calculation; a. thex1、Ax2The areas of the top cover and the cylinder end compression area; lx1、lx2Is area Ax1、Ax2Distance of the center of inertia to the mn axis;
the area and distance of the arch-shaped compression area at the right side of the rotating shaft at the top cover are calculated as follows:
Ax1＝(δ-λsinδ)R2 (12)
the area and distance of the right arc-shaped compression area of the rotating shaft at the barrel end are calculated as follows:
Ax2＝δ(2Rt-t2) (14)
in the formula: t is the wall thickness of the cylindrical foundation;
c. the anti-overturning moment provided by the passive soil pressure is not counted in the calculation of the anti-overturning moment;
d. anti-overturning moment provided by side friction resistance:
Mfs＝2Qgeneral assemblyR(2sinδ′-2λ′δ′+λ′π)/π (16)
In the formula: qGeneral assemblyThe total side frictional resistance of the cylindrical foundation comprises inner side frictional resistance and outer side frictional resistance;
when in the cohesive soil layer, the friction resistance of the soil body side in unit area of the cylinder wall is calculated according to the following formula:
fs＝αSu (17)
in the formula: alpha is a dimensionless coefficient; suTo calculate the non-drainage shear strength of the soil at the point,
the coefficient α is calculated by either:
α＝0.5Ψ0.5，Ψ≤1.0 (18)
α＝0.5Ψ0.25，Ψ＞1.0
with the proviso that alpha is not more than 1.0
In the formula: psi is c/P 'at the computation point'0(ii) a c is clay cohesion, P'0Calculating effective overburden pressure for the point;
when the soil enters the cohesionless soil layer, the frictional resistance of the soil body side in unit area of the cylinder wall is calculated according to the following formula:
fs＝KPo＇tanδ (19)
in the formula: k is a lateral soil pressure coefficient; p'0Calculating effective overburden pressure for the point; delta is the angle of friction between the soil and the wall of the cylinder.
In some embodiments, the respective part overturning moment is calculated as follows:
a. overturning moment generated by horizontal load:
MH＝QHL (21)
in the formula: qHFor horizontal loads acting at the center of the top cover.
b. External bending moment load M0
c. The overturning moment generated by the active soil pressure is not counted in the calculation of the overturning moment.
In some embodiments, a minimum safety factor of 1.35 is set, and when the calculated minimum safety factor is greater than 1.35, the calculation is qualified.
The invention has the beneficial effects that:
therefore, according to the embodiment of the disclosure, the method for checking the anti-overturning stability of the barrel-shaped foundation in the barrel wall bearing mode is provided based on the stress model of the large-diameter wide and shallow barrel-shaped foundation which plays an anti-overturning role in the barrel-soil separation and the frictional resistance of the inner wall and the outer wall of the barrel. On the basis of analyzing a large amount of test data and numerical simulation results, the most dangerous overturning rotating shaft of the cylindrical foundation is sought by adopting thought iteration trial calculation of extremum solving, and the method for calculating the overturning safety coefficient of the cylindrical foundation is obtained, so that the overturning stability of the offshore wind power large-diameter cylindrical foundation under the extreme wind wave current load can be accurately evaluated, the engineering practice is met, the method is simple and clear, the aim of accurately checking the overturning stability of the cylindrical foundation is fulfilled, and the method can also be used for similar ocean engineering foundation types such as polygonal cylindrical foundations, raft foundations with skirts and the like.
Drawings
The invention is further illustrated by means of the attached drawings, but the embodiments in the drawings do not constitute any limitation to the invention, and for a person skilled in the art, other drawings can be obtained on the basis of the following drawings without inventive effort.
FIG. 1 is a schematic diagram of a stress model in a barrel foundation anti-overturning stability checking method based on barrel soil separation disclosed by the invention.
FIG. 2 is a schematic view (unit: mm) of the cylinder type base in example 1.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, when it is described that a specific device is located between a first device and a second device, there may or may not be an intervening device between the specific device and the first device or the second device. When a particular device is described as being coupled to other devices, that particular device may be directly coupled to the other devices without intervening devices or may be directly coupled to the other devices with intervening devices.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.
The applicant researches and discovers that:
in offshore wind power engineering, a cylindrical foundation is commonly used, wherein the large-diameter wide-shallow cylindrical foundation consists of a dome cover and a cylindrical skirt embedded into a seabed at a certain depth, under the action of overturning load, a cylinder and an internal soil body generate certain cooperative motion and relative motion, and the anti-overturning bearing mode of the cylindrical foundation is different from that of a circular shallow foundation without a cylindrical skirt and a pier foundation with the same height-diameter ratio. Tests and finite element researches show that in a soil body with poor cohesiveness, the cooperative motion degree of the cylinder body and the internal soil body is low, and no corresponding theoretical method exists for the calculation of the anti-overturning stability under the cylinder-soil separation setting at present, so that a simplified method for the basic anti-overturning stability of the cylinder-soil separation calculation is needed.
In view of the above, referring to fig. 1, the present disclosure provides a method for checking the anti-overturning stability of a barrel-shaped foundation based on barrel-soil separation, comprising the following steps:
(1) anti-overturning bearing stress model for building barrel-soil separated barrel-shaped foundation
The model is established on the basis that the barrel and the soil body in the barrel can generate relative motion under the action of overturning load, because when the cohesiveness of the foundation soil body is low, the barrel and the soil body in the barrel generate relative motion under the action of overturning load, the inner side and the outer side of the wall surface of the barrel bear frictional resistance, and the inner side and the outer side of the barrel wall exert the anti-overturning effect; as shown in fig. 1, under the action of the overturning load, the foundation is set to rotate around a bottom surface rotation axis mn, an intersection point of mn and a cylinder foundation diameter ab is set as x, and the distance between the point and the center of the foundation is related to the foundation radius as follows: ox ═ λ R, and the angle between ab and om is δ ═ arccos λ. The cylinder bottom is supported by an arc-shaped area, the foundation reaction force of the arch-shaped pressure area at the top cover can provide an anti-overturning moment, and the overturning moment provided by passive soil pressure and the overturning moment generated by active soil pressure take the soil pressure on the inner side and the outer side of the cylinder wall into consideration; the anti-overturning moment provided by the side friction resistance takes the friction resistance on the inner side and the outer side of the cylinder wall into consideration;
(2) calculating the anti-overturning moment MR and the overturning moment Mq of the cylinder;
the anti-overturning moment MRComprises the following steps:
MR＝MV+MR1+MEp+Mfs (1)
in the formula: mVThe anti-tilting moment is provided for vertical force and self weight; mR1The anti-overturning moment is provided for the foundation counterforce in the arc-shaped area of the cylinder end and the anti-overturning moment is provided for the foundation counterforce in the arc-shaped area of the cylinder top cover; mEpProviding passive earth pressure inside and outside the foundationThe anti-overturning moment of (a); mfsThe anti-overturning moment is provided for the friction resistance of the inner side and the outer side of the foundation.
The overturning moment MqComprises the following steps:
Mq＝MH+M0+MEa (20)
in the formula: mHOverturning moment generated by horizontal load; m0Moment load acting on the foundation; mEaIndicating the overturning moment generated by the active earth pressure outside the foundation.
The moment of each part is calculated as follows:
wherein, each part anti-overturning moment is calculated as follows:
a. anti-overturning moment provided by vertical load:
MV＝(QV+G)λR (10)
in the formula: qVIs a vertical load; g is the basis dead weight;
b. the anti-overturning moment that top cap and barrel end foundation counter-force provided:
Mx＝qu1Ax1lx1+qu2Ax2lx2 (11)
in the formula: q. q.su1、qu2The characteristic value of the bearing capacity of the foundation at the pressed positions of the top cover and the cylinder end can be determined by field tests such as load tests, static sounding and the like and formula calculation; a. thex1、Ax2The areas of the top cover and the cylinder end compression area; lx1、lx2Is area Ax1、Ax2Distance of the center of inertia to the mn axis;
the area and distance of the arch-shaped compression area at the right side of the rotating shaft at the top cover are calculated as follows:
Ax1＝(δ-λsinδ)R2 (12)
the area and distance of the right arc-shaped compression area of the rotating shaft at the barrel end are calculated as follows:
Ax2＝δ(2Rt-t2) (14)
in the formula: t is the wall thickness of the cylindrical foundation;
c. anti-overturning moment provided by passive earth pressure: the actual engineering foundation is mostly stratified soil, and the anti-overturning moment of the passive soil pressure is calculated in a layered mode. Because the basic inclination rate of the fan is required to be not more than 0.5 degrees, the active and passive soil pressure of the cylinder wall under the small inclination rate is difficult to calculate accurately, and the passive soil pressure is greater than the active soil pressure, the active and passive soil pressure can be used as a safety reserve in the actual checking calculation, and the calculation of the anti-overturning moment is not included.
d. Anti-overturning moment provided by side friction resistance:
Mfs＝2Qgeneral assemblyR(2sinδ′-2λ′δ′+λ′π)/π (16)
In the formula: qGeneral assemblyThe total side frictional resistance of the cylindrical foundation comprises inner side frictional resistance and outer side frictional resistance;
when in the cohesive soil layer, the friction resistance of the soil body side in unit area of the cylinder wall is calculated according to the following formula:
fs＝αSu (17)
in the formula: alpha is a dimensionless coefficient; suTo calculate the non-drainage shear strength of the soil at the point,
the coefficient α is calculated by either:
α＝0.5Ψ0.5，Ψ≤1.0 (18)
α＝0.5Ψ0.25，Ψ＞1.0
with the proviso that alpha is not more than 1.0
In the formula: psi is c/P 'at the computation point'0(ii) a c is clay cohesion, P'0To calculate the points haveEffectively covering soil pressure;
when the soil enters the cohesionless soil layer, the frictional resistance of the soil body side in unit area of the cylinder wall is calculated according to the following formula:
fs＝KPo＇tanδ (19)
in the formula: k is a lateral soil pressure coefficient; p'0Calculating effective overburden pressure for the point; delta is the angle of friction between the soil and the wall of the cylinder.
Wherein, each part overturning moment is calculated as follows:
a. overturning moment generated by horizontal load:
MH＝QHL (21)
in the formula: qHFor horizontal loads acting at the center of the top cover.
b. External bending moment load M0
c. Overturning moment generated by active soil pressure: because the anti-overturning moment provided by the passive soil pressure is larger than the overturning moment generated by the active soil pressure, the anti-overturning moment can be used as a safety reserve in the actual checking calculation, and the calculation of the overturning moment is not included.
(3) Calculating the minimum value of the anti-overturning safety coefficient and the corresponding position of the rotating shaft
The anti-overturning safety coefficient:
SFt＝MR/Mq (31)
the conventional pier foundation anti-overturning stability checking calculation generally takes the front toe of the foundation bottom surface as a rotating shaft, and for a cylindrical foundation, the rotating shaft is uncertain, so that the most dangerous situation is found, the range of the rotating center of the cylindrical foundation is obtained according to the test and finite element calculation, and the anti-overturning safety coefficient in the range is derived from lambda:
according to (32), the position of the foundation around the bottom surface rotating shaft mn is obtained through iterative trial calculation, and after the rotating shaft position of the foundation is determined, the minimum safety factor of the barrel-shaped foundation for resisting overturning is calculated.
As an implementation mode, in the actual engineering, the soil in the barrel is linked with the barrel to a certain extent, the minimum safety factor is set to be 1.35 by considering the action of the soil in the barrel, and the minimum safety factor is qualified through checking calculation when the calculated minimum safety factor is greater than 1.35.
The following detailed description is made with reference to the embodiments and the accompanying drawings.
Example 1: as shown in fig. 2, a certain offshore wind power project is located in the south-east coast of china, the single-machine capacity is 3.3MW, a single-cylinder multi-cabin cylinder type foundation is adopted, wherein the outer diameter D of the cylinder type foundation is 30m, the wall thickness t of the cylinder side is 0.025m, and the soil penetration height h of the foundation is 9.0 m.
The geological conditions of the positions of the fans are shown in the following table 1.
TABLE 1 soil layer parameter table
The load combination of the fan under the extreme working condition of the bearing capacity limit state is shown in table 2.
TABLE 23.3 MW Fan antidumping checking calculation load combination value
First, the underlying rotation axis position is determined by iterative calculation: ox is 4.6 m.
The vertical load and the dead weight of the foundation provide the anti-inclination moment as follows:
MV＝(V+Gb)λR＝(4.61+20.6)×4.6＝115.97MNm
the section of thick bamboo tip soil layer is the silt layer, and foundation bearing capacity eigenvalue is 320kPa, and section of thick bamboo top cap soil layer is the silt layer, and foundation bearing capacity eigenvalue is 130kPa, and the anti moment of inclining that the foundation bearing capacity provided does:
MR1＝0.13×217.26×4.31+0.32×0.94×6.7＝123.75MNm
the anti-tilting moment provided by the frictional resistance is as follows:
Mfs＝2×2Qgeneral assemblyR(2sinδ′-2λ′δ′+λ′π)/π
＝2×2×1.64×15×(2×sin1.39-2×0.18×1.39+0.18×3.14)
＝199.7MNm
Anti-tilting moment M provided by passive lateral soil pressureEpGreater than the overturning moment M generated by the driving sideEaTherefore, considering the action of the earth pressure as a safe reserve of the anti-tilting capability of the cylinder foundation, and not counting the total anti-tilting moment, the anti-tilting moment of the cylinder foundation is:
MR＝MR1+Mfs+MV＝123.75+199.7+115.97＝439.42MNm
the overturning moment caused by the horizontal load is: mH＝8.2×9＝73.81MNm
The external bending moment load on the cylinder foundation is as follows: m0＝1.68×26+6.5×9.5+127.2＝232.6MNm
The overturning moment applied to the cylindrical foundation is as follows: mq＝MH+M0＝73.81+232.6＝306.44MNm
Thus, the safety factor against overturning of the drum foundation is:
the calculated minimum safety coefficient is greater than the minimum safety coefficient by 1.35, the calculation is qualified, and the requirement of anti-overturning stability is met.
Compared with the prior art, the invention provides a barrel foundation anti-overturning stability checking calculation method based on barrel soil separation, and provides a barrel foundation anti-overturning stability calculation method in a barrel wall bearing mode based on a stress model in which barrel soil separation and frictional resistance of inner and outer walls of a barrel play an anti-overturning role.
Compared with the traditional anti-overturning calculation method taking the front toe of the base bottom surface as the rotating shaft, the method combines the test and the numerical analysis, adopts the idea of obtaining the extreme value to iteratively calculate the position of the most dangerous rotating shaft, and obtains the minimum safety factor of the barrel-shaped base anti-overturning.
The method is in line with engineering practice, simple and clear, realizes the purpose of accurately checking and calculating the anti-overturning stability of the cylinder foundation, and can be used for similar ocean engineering foundation types such as polygonal cylinder foundations, raft foundations with skirt boards and the like.
Finally, it should be emphasized that the present invention is not limited to the above-described embodiments, but only the preferred embodiments of the invention have been described above, and the present invention is not limited to the above-described embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (6)
1. A barrel-type foundation anti-overturning stability checking calculation method based on barrel-soil separation is characterized by comprising the following steps:
(1) anti-overturning bearing stress model for building barrel-soil separated barrel-shaped foundation
The model is established on the basis that the barrel and the soil body in the barrel can generate relative motion under the action of overturning load, and the inner side and the outer side of the wall surface of the barrel bear frictional resistance; under the action of overturning load, setting the foundation to rotate around a bottom surface rotating shaft mn;
(2) calculating the anti-overturning moment M of the cylinderRAnd an overturning moment Mq；
(3) Calculating the minimum value of the anti-overturning safety coefficient and the corresponding position of the rotating shaft
The anti-overturning safety coefficient:
SFt＝MR/Mq (31)
to determine the most dangerous situation, the antidumping safety factor is derived from λ:
according to (32), the position of the foundation around the bottom surface rotating shaft mn is obtained through iterative trial calculation, and the minimum safety factor of the barrel-type foundation against overturning is calculated.
2. The method for checking the overturning resistance stability of a barrel-shaped foundation based on barrel soil separation as claimed in claim 1,
the anti-overturning moment MRComprises the following steps:
MR＝MV+MR1+MEp+Mfs (1)
in the formula: mVThe anti-tilting moment is provided for vertical force and self weight; mR1The anti-overturning moment is provided for the foundation counterforce in the arc-shaped area of the cylinder end and the anti-overturning moment is provided for the foundation counterforce in the arc-shaped area of the cylinder top cover; mEpThe anti-overturning moment is provided for the passive soil pressure on the inner side and the outer side of the foundation; mfsThe anti-overturning moment is provided for the friction resistance of the inner side and the outer side of the foundation.
3. The method for checking the overturning resistance stability of the cylindrical foundation based on cylindrical soil separation as claimed in claim 2,
the overturning moment MqComprises the following steps:
Mq＝MH+M0+MEa (20)
in the formula: mHOverturning moment generated by horizontal load; m0Moment load acting on the foundation; mEaIndicating the overturning moment generated by the active earth pressure outside the foundation.
4. The method for checking the overturning stability of the barrel-shaped foundation based on the barrel-soil separation as claimed in claim 3, wherein the overturning moment of each part is calculated as follows:
a. anti-overturning moment provided by vertical load:
MV＝(QV+G)λR (10)
in the formula: qVIs a vertical load; g is the basis dead weight;
b. the anti-overturning moment that top cap and barrel end foundation counter-force provided:
Mx＝qu1Ax1lx1+qu2Ax2lx2 (11)
in the formula: q. q.su1、qu2Is a top cover and a cylinder endThe bearing capacity characteristic value of the foundation at the pressure position can be determined by field tests such as load tests, static sounding and the like and formula calculation; a. thex1、Ax2The areas of the top cover and the cylinder end compression area; lx1、lx2Is area Ax1、Ax2Distance of the center of inertia to the mn axis;
the area and distance of the arch-shaped compression area at the right side of the rotating shaft at the top cover are calculated as follows:
Ax1＝(δ-λsinδ)R2 (12)
the area and distance of the right arc-shaped compression area of the rotating shaft at the barrel end are calculated as follows:
Ax2＝δ(2Rt-t2) (14)
in the formula: t is the wall thickness of the cylindrical foundation;
c. the anti-overturning moment provided by the passive soil pressure is not counted in the calculation of the anti-overturning moment;
d. anti-overturning moment provided by side friction resistance:
Mfs＝2Qgeneral assemblyR(2sinδ′-2λ′δ′+λ′π)/π (16)
In the formula: qGeneral assemblyThe total side frictional resistance of the cylindrical foundation comprises inner side frictional resistance and outer side frictional resistance;
when in the cohesive soil layer, the friction resistance of the soil body side in unit area of the cylinder wall is calculated according to the following formula:
fs＝αSu (17)
in the formula: alpha is a dimensionless coefficient; suTo calculate the non-drainage shear strength of the soil at the point,
the coefficient α is calculated by either:
α＝0.5Ψ0.5，Ψ≤1.0 (18)
α＝0.5Ψ0.25，Ψ＞1.0
with the proviso that alpha is not more than 1.0
In the formula: psi is c/P 'at the computation point'0(ii) a c is clay cohesion, P'0Calculating effective overburden pressure for the point;
when the soil enters the cohesionless soil layer, the frictional resistance of the soil body side in unit area of the cylinder wall is calculated according to the following formula:
fs＝KP′otanδ (19)
in the formula: k is a lateral soil pressure coefficient; p'0Calculating effective overburden pressure for the point; delta is the angle of friction between the soil and the wall of the cylinder.
5. The method for checking the overturning stability of the barrel-shaped foundation based on the barrel-soil separation as claimed in claim 4, wherein the overturning moment of each part is calculated as follows:
a. overturning moment generated by horizontal load:
MH＝QHL (21)
in the formula: qHFor horizontal loads acting at the center of the top cover.
b. External bending moment load M0
c. The overturning moment generated by the active soil pressure is not counted in the calculation of the overturning moment.
6. The method for checking barrel type foundation overturn-resisting stability based on barrel soil separation as claimed in claim 5, wherein a minimum safety factor is set to be 1.35, and when the calculated minimum safety factor is greater than 1.35, the checking is qualified.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN114809125A (en) * | 2022-04-15 | 2022-07-29 | 中交天津港湾工程研究院有限公司 | Prediction method for anti-tilting stability of steel cylinder |
| CN114809125B (en) * | 2022-04-15 | 2023-09-12 | 中交天津港湾工程研究院有限公司 | Method for predicting anti-tilting stability of steel cylinder |
| WO2023197880A1 (en) * | 2022-04-15 | 2023-10-19 | 中交天津港湾工程研究院有限公司 | Steel cylinder anti-overturning stability prediction method |
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