Design method of flexible connector water supply pipeline buttress

Abstract

The invention relates to a design method of a flexible connector water supply pipeline buttress, which comprises the following steps: calculating to obtain a section extrapolation P borne by a buttress of a bent pipeline, calculating to obtain a first component force borne by the buttress of the bent pipeline according to the section extrapolation P, and enabling the direction of the first component force to be perpendicular to the buttress of the bent pipeline and to face the bent pipeline; friction force between the pipeline and the soil is obtained through calculation, second component force corresponding to the friction force is obtained through calculation according to the friction force, and the direction of the second component force is opposite to that of the first component force; according to the first component force F1 and the second component force, the resultant force in the direction perpendicular to the buttress of the elbow pipeline is obtained through calculation; and obtaining the buttress volume meeting the buttress stability requirement according to the resultant force. Compared with the prior art, the influence of friction force is considered, the obtained buttress meeting the stability requirement of the buttress is small in size, and the concrete dosage is correspondingly reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of abutment design, and particularly relates to a design method for a flexible joint water supply pipeline abutment. Background Art

[0002] Existing flexible joint water supply pipeline abutments are generally designed according to the following principles:

[0003] For the abutments of horizontal elbow pipelines and the abutments of vertically upward elbow pipelines, the abutment design needs to consider the first component force F of the pipeline cross-section external thrust perpendicular to the abutment of the elbow pipeline 1 , the active earth pressure F on the thrust side of the abutment epk , the passive earth pressure F on the anti-thrust side of the abutment pk and the frictional force F on the sliding surface at the bottom of the abutment fk , and perform the abutment stability calculation according to the formula F pk - F epk + F fk ≥ KsF 1 , that is, obtain the resultant force value of F pk , F epk , F fk , and then obtain the volume of the abutment according to the resultant force value of F pk , F epk , F fk ; for the abutment of the horizontal elbow pipeline, the aforementioned first component force F 1 is equal to the standard value F of the water pressure resultant force generated by the cross-section external thrust P on the abutment wpk , for the abutment of the vertically upward elbow pipeline, the aforementioned first component force F 1 is equal to the component force F of the pipeline cross-section external thrust P in the direction perpendicular to the abutment of the elbow pipeline Fh ; where Ks is the anti-sliding stability coefficient, generally taken as 1.5;

[0004] For the abutment of the vertically downward elbow pipeline, the abutment design needs to consider the first component force F of the pipeline cross-section external thrust perpendicular to the abutment of the elbow pipeline 1 and the frictional force F on the sliding surface at the bottom of the abutment fk , and perform the abutment stability calculation according to the formula F fk ≥ KsF 1 , that is, obtain the value of F fk , and then obtain the volume of the abutment according to the value of F fk , where for the abutment of the vertically downward elbow pipeline, the aforementioned first component force F 1 is equal to the component force F of the pipeline cross-section external thrust P in the direction perpendicular to the abutment of the elbow pipeline Fh ; where Ks is the anti-sliding stability coefficient, generally taken as 1.5.

[0005] For the aforementioned calculation process, the self-weight of the abutment determines the frictional force F fk on the sliding surface at the bottom of the abutment. Therefore, in order to obtain a larger frictional force, the volume of the abutment often needs to be made very large.

[0006] However, in actual engineering, pipelines are usually laid underground. The frictional force between the pipeline and the soil actually exists and cannot be ignored. The direction of this frictional force is opposite to that of the first component force F 1 of the abutment perpendicular to the elbow pipeline corresponding to the external thrust of the pipeline cross-section. Therefore, the volume of the abutment calculated by the existing technology is relatively large, and a relatively large amount of concrete is required accordingly. Summary of the Invention

[0007] In order to solve all or part of the above problems, the purpose of the present invention is to provide a design method for the abutment of a flexible joint water supply pipeline. The abutment volume obtained by the design method of the abutment of the flexible joint water supply pipeline of the present invention is relatively small, and the amount of concrete used is correspondingly reduced.

[0008] According to one aspect of the present invention, there is provided a design method for the abutment of a flexible joint water supply pipeline, including:

[0009] Calculating the external thrust of the cross-section borne by the abutment of the elbow pipeline, and calculating the first component force received by the abutment of the elbow pipeline according to the external thrust of the cross-section. The direction of the first component force is perpendicular to the abutment of the elbow pipeline and towards the elbow pipeline;

[0010] Calculating the frictional force between the pipeline and the soil, and calculating the second component force corresponding to the frictional force according to the frictional force. The direction of the second component force is opposite to the direction of the first component force;

[0011] Calculating the resultant force in the direction perpendicular to the abutment of the elbow pipeline according to the first component force and the second component force;

[0012] Obtaining the abutment volume that meets the abutment stability requirements according to the resultant force.

[0013] Further, the calculating the external thrust of the cross-section borne by the abutment of the elbow pipeline and calculating the first component force received by the abutment of the elbow pipeline according to the external thrust of the cross-section further includes:

[0014] Calculating the external thrust of the cross-section borne by the abutment of the elbow pipeline according to the designed inner diameter of the pipeline interface and the designed inner water pressure of the pipeline;

[0015] For the abutment of the horizontal elbow pipeline, calculating the hydraulic resultant force generated by the external thrust of the cross-section on the abutment of the elbow pipeline, and obtaining the first component force received by the abutment of the elbow pipeline according to the hydraulic resultant force;

[0016] For the piers of the elbow pipes with vertical upward bends and vertical downward bends, the third component force and the fourth component force corresponding to the external thrust of the cross-section are respectively calculated, and the first component force received by the pier of the elbow pipe is obtained according to the fourth component force, wherein the direction of the fourth component force is the same as the direction of the first component force, and the third component force is perpendicular to the fourth component force.

[0017] Further, the specific calculation method for obtaining the external thrust of the cross-section borne by the pier of the elbow pipe according to the designed inner diameter of the pipe joint and the designed internal water pressure of the pipe is as follows:

[0018] The external thrust of the cross-section is equal to 0.785 times the square of the designed inner diameter of the elbow pipe joint multiplied by the designed internal water pressure of the elbow pipe and divided by one thousand.

[0019] Further, for the pier of the horizontal elbow pipe, according to the external thrust of the cross-section, the hydraulic pressure resultant force generated by the external thrust of the cross-section on the pier of the elbow pipe is calculated, and the specific method for obtaining the first component force received by the pier of the elbow pipe according to the hydraulic pressure resultant force is as follows:

[0020] For the pier of the horizontal elbow pipe, according to the external thrust of the cross-section and the bending angle of the elbow pipe, the hydraulic pressure resultant force is calculated, wherein the hydraulic pressure resultant force is equal to one-half times the sine value of the bending angle of the elbow pipe multiplied by 2 times the external thrust of the cross-section;

[0021] The first component force received by the pier of the elbow pipe is equal to the hydraulic pressure resultant force.

[0022] Further, for the piers of the elbow pipes with vertical upward bends and vertical downward bends, the third component force and the fourth component force corresponding to the external thrust of the cross-section are respectively calculated, and the specific method for obtaining the first component force received by the pier of the elbow pipe according to the fourth component force is as follows:

[0023] For the piers of the elbow pipes with vertical upward bends and vertical downward bends, the third component force and the fourth component force corresponding to the external thrust of the cross-section are respectively calculated according to the external thrust of the cross-section and the bending angle of the elbow pipe; wherein, for the piers of the elbow pipes with vertical upward bends and vertical downward bends, the third component force is equal to the sine value of the bending angle of the pipe multiplied by the external thrust of the cross-section; for the piers of the elbow pipes with vertical upward bends and vertical downward bends, the fourth component force is equal to the product of negative one times the sum of the cosine value of the bending angle of the elbow pipe and one and the external thrust of the cross-section;

[0024] The first component force received by the pier of the elbow pipe is equal to the fourth component force.

[0025] Further, the calculation of the friction force between the pipe and the soil and the calculation of the second component force corresponding to the friction force further include:

[0026] Calculate the friction force per unit length of the pipeline;

[0027] Calculate the friction force between the pipeline and the soil based on the friction force per unit length of the pipeline and the length of the elbow;

[0028] Calculate the second component force corresponding to the friction force based on the friction force between the pipeline and the soil.

[0029] Further, the calculation of the friction force per unit length of the pipeline is specifically as follows:

[0030] Calculate the friction force per unit length of the pipeline based on the friction coefficient between the pipeline and the soil, the outer diameter of the pipeline wall, the covering height from the top of the pipe to the designed ground surface, the specific weight of water in the pipeline, the specific weight of the backfill soil, and the calculated thickness of the pipe wall.

[0031] Further, the calculation of the friction force between the pipeline and the soil based on the friction force per unit length of the pipeline and the length of the elbow is specifically as follows: Set the length of the elbow as the length of the pipeline between the two flexible joints on both sides of the abutment, and the friction force between the pipeline and the soil is equal to the friction force per unit length of the pipeline multiplied by the length of the elbow;

[0032] The calculation of the second component force corresponding to the friction force based on the friction force between the pipeline and the soil is specifically as follows: The second component force corresponding to the friction force is equal to one-half times the sine value of the angle α of the pipeline bend multiplied by 2 multiplied by the friction force per unit length of the pipeline multiplied by the length of the elbow.

[0033] Further, the calculation of the resultant force in the direction of the abutment perpendicular to the elbow pipeline based on the first component force and the second component force is specifically as follows:

[0034] The resultant force in the direction of the abutment perpendicular to the elbow pipeline is equal to the first component force minus the second component force.

[0035] Further, the calculation of the abutment volume that meets the abutment stability requirements based on the resultant force further includes:

[0036] For the abutments of horizontal elbow pipelines and vertical upward elbow pipelines, based on the resultant force and the anti-sliding stability resistance coefficient, obtain the resultant force value of the active earth pressure on the thrust side of the abutment, the friction force on the sliding surface at the bottom of the abutment, and the passive earth pressure on the anti-thrust side of the abutment that meet the abutment stability requirements, and obtain the volume of the abutment based on the resultant force value;

[0037] For the abutments of vertical downward elbow pipelines, based on the resultant force and the anti-sliding stability resistance coefficient, obtain the friction force on the sliding surface at the bottom of the abutment that meets the abutment stability requirements, and obtain the volume of the abutment based on the friction force on the sliding surface at the bottom of the abutment.

[0038] As can be seen from the above technical solution, a design method for a flexible joint water supply pipeline pier provided by the present invention has the following beneficial effects:

[0039] Compared with the prior art, the present invention takes into account the influence of friction, and the volume of the pier that meets the requirements of pier stability obtained is smaller, correspondingly reducing the amount of concrete used. Description of the Drawings

[0040] Figure 1 is a flowchart of the design method for the flexible joint water supply pipeline pier of the embodiment of the present invention;

[0041] Figure 2 is a top view of the horizontal elbow pipeline and the pier;

[0042] Figure 3 is Figure 2 a cross-sectional view of the A-A section in

[0043] Figure 4 is an elevation view of the vertically upward bent elbow pipeline and the pier;

[0044] Figure 5 is Figure 4 a cross-sectional view of the B-B section in

[0045] Figure 6 is an elevation view of the vertically upward bent elbow pipeline and the pier;

[0046] Figure 7 is Figure 6 a cross-sectional view of the C-C section in

[0047] Figure 8 is a force diagram of the horizontal elbow pipeline and the pier. Detailed Embodiment

[0048] In order to better understand the purpose, structure and function of the present invention, the following further describes in detail a design method for a flexible joint water supply pipeline pier of the present invention with reference to the drawings.

[0049] As Figure 1 shown, a design method for a flexible joint water supply pipeline pier of an embodiment of the present invention includes the following steps:

[0050] Step S01: Calculate the external thrust P on the section borne by the pier of the elbow pipeline, and calculate the first component force F 1 received by the pier of the elbow pipeline according to the external thrust P, and the direction of the first component force is perpendicular to the pier of the elbow pipeline and towards the elbow pipeline;

[0051] Step S02: Calculate the friction force between the pipeline and the soil, and calculate the second component force F corresponding to the friction force according to the friction force. fp , the direction of the second component force F fp is opposite to the direction of the first component force;

[0052] Step S03: Calculate the resultant force in the direction of the pier perpendicular to the elbow pipeline according to the first component force F 1 and the second component force F fp ;

[0053] Step S04: Obtain the volume of the pier that meets the pier stability requirements according to the resultant force.

[0054] In the embodiment of the present invention, the influence of the friction force between the elbow pipeline and the soil on the calculation of the pier volume is considered, and accordingly, the second component force corresponding to the friction force is introduced. The direction of the second component force is opposite to that of the first component force. Therefore, a part of the first component force is offset accordingly, thereby reducing the volume of the pier calculated according to the resultant force and reducing the amount of concrete used.

[0055] Among them, in step S01, the sectional external thrust P borne by the pier of the elbow pipeline is calculated, and according to the sectional external thrust P, the first component force F received by the pier of the elbow pipeline is calculated. 1 It further includes:

[0056] S011: Calculate the sectional external thrust P borne by the pier of the elbow pipeline according to the designed inner diameter dn of the pipeline interface and the designed inner water pressure F of the pipeline. wdk ;

[0057] Specifically, the sectional external thrust P is equal to 0.785 times the square of the designed inner diameter dn of the elbow pipeline interface multiplied by the designed inner water pressure F of the elbow pipeline wdk divided by one thousand. That is, according to different designed inner diameters dn of the elbow pipeline interface and designed inner water pressures F of the elbow pipeline wdk , the sectional external thrust P borne by the pier of the elbow pipeline can be calculated according to Equation 1:

[0058] P = 0.785dn 2 F wdk / 1000 Equation 1

[0059] In Equation 1, dn = α D D, where α D is the conversion coefficient between the designed inner diameter of the elbow pipeline interface and the inner diameter of the pipe, and D is the inner diameter of the pipe (unit: mm); the designed inner water pressure F of the elbow pipeline wdk (unit: MPa) is usually obtained by multiplying the working pressure of pipes of different materials by a coefficient.

[0060] After calculating the external thrust P on the cross-section borne by the pier of the elbow pipe, the first component force F on the pier of the elbow pipe can be calculated according to the external thrust P on the cross-section. 1 For the piers of horizontal elbow pipes, and for the piers of elbow pipes bent vertically upward and vertically downward, the calculations of their first component forces are as follows:

[0061] S012: For the pier of a horizontal elbow pipe, according to the external thrust P on the cross-section, calculate the hydraulic pressure resultant force F generated by the external thrust P on the pier of the elbow pipe. wpk According to the hydraulic pressure resultant force F wpk the first component force F on the pier of the elbow pipe is obtained. 1 .

[0062] Specifically, for the pier of a horizontal elbow pipe, according to the external thrust P on the cross-section and the bending angle α of the elbow pipe, calculate the hydraulic pressure resultant force F. wpk That is, according to the external thrust P on the cross-section and the bending angle α of the elbow pipe, the hydraulic pressure resultant force F can be calculated according to Equation (2). wpk :

[0063]

[0064] It can be seen from Equation (2) that the hydraulic pressure resultant force F wpk is equal to half of the sine value of the bending angle α of the elbow pipe multiplied by 2 times the external thrust P on the cross-section.

[0065] Equation (2) is the hydraulic pressure resultant force F calculated for the pier of a horizontal elbow pipe. wpk For a horizontal elbow pipe, the two pipe segments forming the elbow pipe are both in the same plane parallel to the horizontal plane, that is, its bending condition can be seen from the top view; once again, Figure 2 is the top view of the horizontal elbow pipe and the pier, Figure 3 and Figure 2 is the sectional view taken along the A-A direction in Figure 2 and Figure 3 the specific structure of the horizontal elbow pipe can be obtained.

[0066] For the tee and pipe plug, the hydraulic pressure resultant force F generated by the external thrust P on the cross-section on the corresponding pier wpk is equal to the external thrust P on the cross-section.

[0067] For the pier of a horizontal elbow pipe, after calculating the hydraulic pressure resultant force F generated by the external thrust P on the cross-section on the pier of the horizontal elbow pipe. wpk the first component force F on the pier of the horizontal elbow pipe can be obtained according to the hydraulic pressure resultant force, 1 where the first component force F on the pier of the horizontal elbow pipe 1 is equal to the hydraulic pressure resultant force F.wpk .

[0068] For the piers of the elbow pipes with vertical upward bends and vertical downward bends, the third component force N and the fourth component force F corresponding to the external thrust on the cross-section are calculated respectively h , and based on the fourth component force F h the first component force F received by the pier of the elbow pipe is obtained 1 , where the direction of the fourth component force is the same as that of the first component force, and the third component force is perpendicular to the fourth component force.

[0069] Specifically, for the piers of the elbow pipes with vertical upward bends and vertical downward bends, according to the external thrust P on the cross-section and the bending angle α of the elbow pipe, the third component force N and the fourth component force F corresponding to the external thrust P on the cross-section are calculated respectively h ; among them, for the piers of the elbow pipes with vertical upward bends and vertical downward bends, their third component force N is equal to the sine value of the bending angle α of the pipe multiplied by the external thrust P on the cross-section; for the piers of the elbow pipes with vertical upward bends and vertical downward bends, their fourth component force F h is equal to the product of the sum of negative one times the cosine value of the bending angle α of the elbow pipe and one and the external thrust P.

[0070] For the piers of the elbow pipes with vertical upward bends and vertical downward bends, the third component force N corresponding to the external thrust P on the cross-section can be calculated according to Equation 3, and the fourth component force F h corresponding to the external thrust P on the cross-section can be calculated according to Equation 4:

[0071] N = Psinα Equation 3

[0072] F h = P(1 - cosα) Equation 4

[0073] Once again, for the fourth component force F corresponding to the external thrust P on the cross-section h , its direction is the same as that of the first component force, that is, its direction is perpendicular to the pier of the elbow pipe and towards the elbow pipe; for the third component force N corresponding to the external thrust P on the cross-section, it is used to calculate the frictional force F fk .

[0074] For the piers of the elbow pipes with vertical upward bends and vertical downward bends, after calculating the fourth component force F corresponding to the external thrust P on the cross-section h , the first component force F received by the pier of the horizontal elbow pipe can be obtained according to the fourth component force F h corresponding to the external thrust P on the cross-section 1 , where the first component force F received by the pier of the horizontal elbow pipe 1 is equal to the fourth component force F corresponding to the external thrust P on the cross-section h .

[0075] Finally, for the pier of the elbow pipe with a vertical upward bend, the two pipe segments forming the elbow pipe are both in the vertical plane, that is, the bending situation can be seen from the elevation view; again, Figure 4 is the elevation view of the elbow pipe with a vertical upward bend and the pier, Figure 5 then it is Figure 4 the sectional view taken along the B-B direction in Figure 4 and Figure 5 the specific structure of the elbow pipe with a vertical upward bend can be obtained.

[0076] For the pier of the elbow pipe with a vertical downward bend, the two pipe segments forming the elbow pipe are both in the vertical plane, that is, the bending situation can be seen from the elevation view; again, Figure 6 is the elevation view of the elbow pipe with a vertical upward bend and the pier, Figure 7 then it is Figure 6 the sectional view taken along the C-C direction in Figure 6 and Figure 7 the specific structure of the elbow pipe with a vertical upward bend can be obtained.

[0077] Among them, in step S02, the friction force between the pipe and the soil is calculated, and the second component force F corresponding to the friction force is calculated according to the friction force fp which further includes:

[0078] S021: Calculate the friction force per unit length of the pipe F fpk .

[0079] Specifically, according to the friction coefficient between the elbow pipe and the soil, the outer diameter of the pipe wall, the covering height from the pipe top to the designed ground surface, the specific weight of the water in the pipe, the specific weight of the backfill soil, and the calculated thickness of the pipe wall, the friction force per unit length of the pipe F fpk can be calculated. The friction force per unit length of the pipe F fpk is as shown in Equation Five:

[0080]

[0081] In Equation Five, μ S represents the friction coefficient between the pipe and the soil, which should be determined by tests. D 1 represents the outer diameter of the pipe wall (m), H S represents the covering height from the pipe top to the designed ground surface (m), γ w represents the standard value of the specific weight of the water in the pipe (which can be taken as 10 kN / m³); γ s represents the specific weight of the backfill soil (kN / m³), and t 0 represents the calculated thickness of the pipe wall (m).

[0082] When determining the friction coefficient between the pipeline and the soil in the above formula, in order to obtain a definite value, the periphery of the pipeline can be backfilled and compacted with medium-coarse sand, and the compaction coefficient is not less than 0.9.

[0083] S022: Calculate the friction force between the pipeline and the soil according to the friction force per unit length of the pipeline and the length L of the elbow g , and the friction force between the pipeline and the soil is obtained.

[0084] Specifically, set the length L of the elbow g as the length of the pipeline between the two flexible joints on both sides of the abutment, then the friction force between the pipeline and the soil is equal to the friction force F per unit length of the pipeline fpk multiplied by the length L of the elbow g , that is, the friction force between the pipeline and the soil is F fpk L g .

[0085] S023: Calculate the second component force F corresponding to the friction force according to the friction force between the pipeline and the soil fp .

[0086] Specifically, the second component force F corresponding to the friction force fp is equal to one-half times the sine value of the angle α of the pipeline bend multiplied by 2 multiplied by the friction force F per unit length of the pipeline fpk multiplied by the length of the elbow, that is, the second component force F corresponding to the friction force fp can be calculated according to Equation 6:

[0087]

[0088] Among them, in step S03, according to the first component force F 1 and the second component force F fp , the resultant force in the direction of the abutment perpendicular to the elbow pipeline is specifically:

[0089] The resultant force in the direction of the abutment perpendicular to the elbow pipeline is equal to the first component force F 1 minus the second component force F fp , that is, F 合 = F 1 - F fp , and the direction of F 合 is the same as the direction of F 1 . The F 合 calculated in this embodiment cancels out the second component force F corresponding to the friction force between the pipeline and the soil fp , so that the value of F 合 is correspondingly smaller than the value obtained in the prior art without considering the friction force. Therefore, the abutment volume that meets the abutment stability requirement obtained by using the value of F 合 is smaller, thereby reducing the amount of concrete used.

[0090] Among them, step S04 of obtaining the pier volume that meets the pier stability requirements according to the resultant force further includes:

[0091] For the horizontal elbow pipe pier and the vertical upward elbow pipe pier, according to the resultant force and the anti-sliding stability resistance coefficient, the active earth pressure F on the thrust side of the pier that meets the pier stability requirements is obtained epk , the friction force F on the sliding surface at the bottom of the pier fk and the passive earth pressure F on the anti-thrust side of the pier pk . According to the resultant force value, the volume of the pier is obtained.

[0092] Specifically, the pier stability requirement here means that it is necessary to meet the requirements of Equation VII, that is

[0093] F pk -F epk +F fk ≥K s F 合 Equation VII

[0094] In Equation VII, K s represents the anti-sliding stability resistance coefficient, F epk represents the active earth pressure on the thrust side of the pier, F fk represents the friction force on the sliding surface at the bottom of the pier, F pk represents the passive earth pressure on the anti-thrust side of the pier. For the horizontal elbow pipe and the pier, the directions of the forces are as Figure 8 shown. From Equation VII and Figure 8 known, after obtaining K s and F 合 , the active earth pressure F on the thrust side of the pier that meets the pier stability requirements can be obtained epk , the friction force F on the sliding surface at the bottom of the pier fk and the passive earth pressure F on the anti-thrust side of the pier pk . Furthermore, according to the resultant force value of the three, the volume of the pier can be obtained.

[0095] For the pier of the vertical downward elbow pipe, according to the resultant force and the anti-sliding stability resistance coefficient, the friction force F on the sliding surface at the bottom of the pier that meets the pier stability requirements is obtained fk . According to the friction force F on the sliding surface at the bottom of the pier fk , the volume of the pier is obtained.

[0096] The pier stability requirement here means that it is necessary to meet the requirements of Equation VII, that is

[0097] F fk ≥KsF 合 Equation VIII

[0098] In Equation VIII, K sDenote the anti-slip stability resistance coefficient, generally taken as 1.5, F fk Denote the frictional force on the sliding surface at the bottom of the abutment pier, which is known from Equation VIII to obtain K s and F 合 After that, the frictional force F on the sliding surface at the bottom of the abutment pier that meets the stability requirements of the abutment pier can be obtained fk , and then based on the frictional force F on the sliding surface at the bottom of the abutment pier fk the volume of the abutment pier can be obtained

[0099] Among them, for the active earth pressure F on the thrust side of the abutment pier epk , the frictional force F on the sliding surface at the bottom of the abutment pier fk and the passive earth pressure F on the anti-thrust side of the abutment pier pk are explained as follows

[0100] The active earth pressure F on the thrust side of the abutment pier epk is divided into two cases: the groundwater level is lower than the bottom surface of the abutment pier and the groundwater level is higher than the bottom surface of the abutment pier. Among them, when the groundwater level is lower than the bottom surface of the abutment pier, Equation IX is used for calculation, and when the groundwater level is higher than the bottom surface of the abutment pier, Equation X is used for calculation

[0101]

[0102] The passive earth pressure F on the anti-thrust side of the abutment pier pk is also divided into two cases: the groundwater level is lower than the bottom surface of the abutment pier and the groundwater level is higher than the bottom surface of the abutment pier. Among them, when the groundwater level is lower than the bottom surface of the abutment pier, Equation XI is used for calculation, and when the groundwater level is higher than the bottom surface of the abutment pier, Equation XII is used for calculation

[0103]

[0104] For Equations IX to XII, the meanings of each symbol are: γ s1 denote the unit weight of the undisturbed soil above the groundwater level (KN / m 3 ); γ s3 denote the unit weight of the backfill soil used in the calculation of the active earth pressure (KN / m 3 ); γ s ' denote the effective unit weight of the soil below the groundwater level (KN / m 3 ); Z 1 denote the depth (m) of the top of the abutment pier below the design ground surface; Z 2 denote the depth (m) of the bottom of the abutment pier below the design ground surface; Z w denote the depth (m) of the groundwater level below the design ground surface; L denote the length (m) of the bottom surface of the abutment pier; φ d denote the equivalent internal friction angle of the soil (°)

[0105] For the piers of horizontal elbow pipes, the piers of vertically upward elbow pipes, and the piers of vertically downward elbow pipes, the frictional force F on the sliding surface at the bottom of the pier fk is calculated according to Equation Thirteen, Equation Fourteen, and Equation Fifteen respectively:

[0106] F fk =(G + W - F fvk )f Equation Thirteen

[0107] F fk =(G + W + N - F fwk )f Equation Fourteen

[0108] F fk =(G + W - N - F fwk )f Equation Fifteen

[0109] For Equation Thirteen, Equation Fourteen, and Equation Fifteen, N represents the third component force (kN) corresponding to the external thrust of the aforementioned cross-section, F fwk represents the standard value of the buoyancy force (KN) exerted on the pier and its top soil cover, F fwk can be obtained by calculating according to Equation Sixteen; G represents the self-weight of the pier concrete (KN), G can be obtained by calculating according to Equation Seventeen; W represents the self-weight of the soil cover on the top of the pier (KN), W can be obtained by calculating according to Equation Eighteen; f represents the friction coefficient of the soil on the bottom of the concrete pier.

[0110] F fvk =γ w A(Z 2 -Z w ) Equation Sixteen

[0111] G = Y c V c Equation Seventeen

[0112] W = Y s 2V s Equation Eighteen

[0113] For Equation Sixteen, Equation Seventeen, and Equation Eighteen, the meanings of each symbol are as follows: Z 2 represents the depth (m) of the bottom of the pier below the design ground surface; Z w represents the depth (m) of the groundwater level below the design ground surface; γ w represents the unit weight of groundwater (kN / m 3 ); A represents the bottom area of the pier (m 2 ), where, for the horizontal pier as shown in Figure 2 , its cross-section is trapezoidal, A = 0.2L + (L + L 0 )B / 2, L represents the length (m) of the bottom surface of the pier, L 0 represents the length of the upper bottom surface of the pier, B represents the height of the trapezoid, for the one as shown inFigures 4 - 7 The vertical pier shown, A = BL; Y C represents the unit weight of concrete (kN / m 3 ); V c represents the volume of pier concrete (m 3 ); Y s2 represents the unit weight of the soil covering the top of the pier and the pipe fitting foundation (kN / m 3 ); V s represents the volume of the soil covering the top of the pier (m 3 ).

[0114] Compared with the prior art, the present invention takes into account the influence of friction, and the volume of the pier that meets the requirements of pier stability obtained is smaller, and accordingly the amount of concrete used is reduced.

[0115] It should be noted that unless otherwise specified, the technical terms or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art to which the present invention belongs.

[0116] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed in the text, but includes all technical solutions falling within the scope of the claims.

Claims

1. A design method for a flexible interface water supply pipeline support, characterized in that: include: Calculate the cross-sectional external thrust borne by the support pier of the elbow pipe, and calculate the first force component borne by the support pier of the elbow pipe according to the cross-sectional external thrust, wherein the direction of the first force component is perpendicular to the support pier of the elbow pipe and toward the elbow pipe; The friction force between the pipeline and the soil is calculated, and a second force component corresponding to the friction force is calculated based on the friction force, wherein the direction of the second force component is opposite to the direction of the first force component; Calculate the resultant force in a direction perpendicular to the buttress of the elbow pipe according to the first force component and the second force component; The volume of the buttress satisfying the buttress stability requirement is obtained according to the resultant force.

2. The method according to claim 1, characterized in that The step of calculating the cross-sectional external thrust borne by the support pier of the elbow pipe and calculating the first force component borne by the support pier of the elbow pipe according to the cross-sectional external thrust further comprises: According to the designed inner diameter of the pipeline interface and the designed internal water pressure of the pipeline, the cross-sectional external thrust borne by the pier of the elbow pipeline is calculated; For the support pier of the horizontal elbow pipe, according to the cross-sectional external thrust, the water pressure resultant force generated by the cross-sectional external thrust on the support pier of the elbow pipe is calculated, and the first component force received by the support pier of the elbow pipe is obtained according to the water pressure resultant force; For the piers of the curved pipe that bends vertically upward and vertically downward, the third force component and the fourth force component corresponding to the cross-sectional external thrust are respectively calculated, and the first force component received by the pier of the curved pipe is obtained according to the fourth force component, wherein the direction of the fourth force component is the same as the direction of the first force component, and the third force component is perpendicular to the fourth force component.

3. The method according to claim 2, characterized in that According to the designed inner diameter of the pipeline interface and the designed internal water pressure of the pipeline, the cross-sectional external thrust borne by the pier of the elbow pipeline is calculated as follows: The cross-sectional external thrust is equal to 0.785 times the square of the design inner diameter of the elbow pipe interface multiplied by the design internal water pressure of the elbow pipe divided by one thousand.

4. The method according to claim 2, characterized in that: For the support pier of the horizontal elbow pipe, the water pressure resultant force generated by the cross-sectional external thrust on the support pier of the elbow pipe is calculated according to the cross-sectional external thrust, and the first component force on the support pier of the elbow pipe obtained according to the water pressure resultant force is specifically: For the support pier of the horizontal curved pipe, the water pressure resultant force is calculated according to the cross-sectional external thrust and the bending angle of the curved pipe, wherein the water pressure resultant force is equal to half the sine value of the bending angle of the curved pipe multiplied by 2 times the cross-sectional external thrust; The first component force on the buttress of the elbow pipe is equal to the resultant water pressure force.

5. The method according to claim 2, characterized in that: For the piers of the curved pipes that bend vertically upward and vertically downward, the third force component and the fourth force component corresponding to the cross-sectional external thrust are calculated respectively, and the first force component received by the piers of the curved pipes is obtained according to the fourth force component: For the piers of the curved pipes that bend vertically upward and vertically downward, the third force component and the fourth force component corresponding to the cross-sectional external thrust are calculated according to the cross-sectional external thrust and the bending angle of the curved pipe respectively; wherein, for the piers of the curved pipes that bend vertically upward and vertically downward, the third force component is equal to the sine value of the pipe bending angle multiplied by the cross-sectional external thrust; for the piers of the curved pipes that bend vertically upward and vertically downward, the fourth force component is equal to the sum of the cosine value of the bending angle of the curved pipe multiplied by one times the cross-sectional external thrust; The first force component received by the buttress of the elbow pipe is equal to the fourth force component.

6. The method according to claim 1, characterized in that The calculating of the friction force between the pipeline and the soil and calculating the second force component corresponding to the friction force according to the friction force further includes: The friction force per unit length of the pipeline is calculated; The friction force between the pipeline and the soil is calculated according to the friction force per unit length of the pipeline and the length of the elbow; According to the friction between the pipeline and the soil, a second component force corresponding to the friction force is calculated.

7. The method according to claim 6, characterized in that The calculated friction force per unit length of the pipeline is specifically: The friction force per unit length of the pipeline is calculated based on the friction coefficient between the pipeline and the soil, the diameter of the outer wall of the pipeline, the soil cover height from the top of the pipe to the designed ground, the weight of the water in the pipeline, the weight of the backfill soil and the calculated thickness of the pipe wall.

8. The method according to claim 6, characterized in that The friction force between the pipeline and the soil is calculated based on the friction force per unit length of the pipeline and the length of the elbow pipe as follows: the length of the elbow pipe is set to be the length of the pipeline between the two flexible interfaces on both sides of the pier, and the friction force between the pipeline and the soil is equal to the friction force per unit length of the pipeline multiplied by the length of the elbow pipe; The second component force corresponding to the friction force calculated based on the friction force between the pipeline and the soil is specifically: the second component force corresponding to the friction force is equal to half the sine value of the angle α of the pipeline bending multiplied by 2 multiplied by the friction force per unit length of the pipeline multiplied by the length of the bent pipe.

9. The method according to claim 1, characterized in that: The resultant force in the direction perpendicular to the buttress of the elbow pipe is calculated based on the first force component and the second force component as follows: The resultant force perpendicular to the buttress direction of the elbow pipe is equal to the first force component minus the second force component.

10. The method according to claim 1, characterized in that The pier volume that meets the pier stability requirement is obtained according to the combined force further comprising: For the piers of the horizontal curved pipe and the piers of the vertically curved pipe, the resultant value of the active earth pressure on the thrust side of the pier, the friction force on the sliding surface at the bottom of the pier and the passive earth pressure on the thrust side of the pier that meet the stability requirements of the pier is obtained according to the resultant force and the anti-sliding stability resistance coefficient, and the volume of the pier is obtained according to the resultant force value; For a pier of a curved pipe that bends vertically downward, the friction force on the sliding surface at the bottom of the pier that meets the stability requirements of the pier is obtained based on the resultant force and the anti-sliding stability resistance coefficient, and the volume of the pier is obtained based on the friction force on the sliding surface at the bottom of the pier.

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