Analysis method for maximum actual covering depth of reinforced concrete sewer

Abstract

The application discloses a reinforced concrete drainage pipe maximum actual covering depth analysis method, comprising the following steps: 1, calculating the bending moment standard value and the axial force standard value of point A, two side points C and the uppermost point B under the pipe section; 2, according to the actual engineering situation and the soil parameters, taking the pipe top covering depth H s as a variable, the internal force design value of the jacking construction method drainage pipe engineering state is calculated, and a function relationship formula is obtained, in which the pipe top covering depth H s is the independent variable, and the pipe internal force design value M' di and N' di are the dependent variables; 3, the function relationship formula is adjusted by adjusting H s , and the positive calculation is clamped and fitted; M' di and N' di are respectively close to the three-point method experimental crack load of the national standard I, II and III pipes, and the corresponding H s corresponding to the fitting calculation result is obtained in the engineering allowable error range. The application can improve the design efficiency, reduce the design errors, avoid the engineering accidents caused by the weak pipe material selection under the condition of ensuring the safety and quality, and fully exert the pipeline performance.

Description

Technical Field

[0001] This invention relates to the field of computer-aided design technology, and in particular to an analysis method for the maximum actual soil cover depth of reinforced concrete drainage pipes. Background Technology

[0002] In existing technologies, the strength grades of reinforced concrete drainage pipes used in jacking construction are classified in the same way as reinforced concrete pipes. They are usually classified into Grade I, Grade II, and Grade III pipes according to the national standard GB / T11836, using the three-point test crack load P as the grade classification standard.

[0003] The P-value is an experimental standard value, which is difficult to correspond to the diverse soil properties and parameters across a wide area. Taking Class II pipe as an example, the maximum actual overburden depth that the pipe can withstand varies greatly when jacking pipes in soil environments with different properties.

[0004] In practical applications, the aforementioned existing technologies have created significant obstacles for designers in selecting pipe types for specific projects. Most of the selections are based on empirical assumptions, such as soil cohesion C = 0 kPa and internal friction angle φ = 30°, which are lacking in both safety and economy.

[0005] Moreover, each design involves a large number of repetitive mathematical calculations, which not only takes up a lot of design time but is also prone to errors.

[0006] Therefore, how to improve design efficiency, reduce design errors, and avoid engineering accidents caused by weak pipe material selection while ensuring safety and quality, and fully utilize the performance of pipe materials, has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] In view of the above-mentioned deficiencies of the prior art, the present invention provides the maximum actual soil cover depth of the pipe top when the national standard reinforced concrete drainage pipe is applied to the jacking construction method. The purpose is to improve design efficiency, reduce design errors, and avoid engineering accidents caused by weak pipe material selection while ensuring safety and quality, so as to give full play to the performance of the pipe material.

[0008] To achieve the above objectives, this invention discloses an analysis method for the maximum actual soil cover depth of reinforced concrete drainage pipes, comprising the following steps:

[0009] Step 1: Calculate the standard value M of the bending moment at point A at the bottom of the tube section, points C on both sides, and point B at the top under experimental conditions. KA M KB and M KC and the standard value of axial force N KA N KB and N KC ;

[0010] Step 2: Based on the actual engineering conditions and soil parameters, determine the overburden depth H above the pipe. s As a variable, the internal force design value M' of the drainage pipe project state in the jacking construction method is calculated. di and N' di The depth of soil cover H at the top of the pipe is obtained. s The design value of the internal force M' of the pipe is the independent variable. di and N' di The functional relationship between the dependent and dependent variables;

[0011] Step 3: Adjust H in the functional relationship. s The results of the positive squeeze fitting calculation; make M' di and N' di By approximating the crack load P from the three-point method experiments for Class I, Class II, and Class III pipes according to national standards to within the allowable error range in engineering, the corresponding H values ​​for the fitted calculations of Class I, Class II, and Class III pipes were obtained. s The maximum actual overburden depth of the pipe jacking is denoted as H. sMAXI H sMAXII and H sMAXIII .

[0012] Preferably, step 1 is as follows:

[0013] Step 1.1: Obtain the nominal inner diameter D0, wall thickness t, and concrete density γ of the drainage pipe to be analyzed.

[0014] Step 1.2: Calculate the pipe's radius r0 and its weight per unit length G. 1k The specific formula is as follows:

[0015] r0 = (D0 + t) / 2;

[0016] G 1k =2πr0×t×γ;

[0017] Step 1.3: Obtain the crack load P in the three-point method experiment, and the internal force coefficients α at the lowest point A, two side points C, and the highest point B of the cross-section caused by the pipe's self-weight. MA α MB α MC α NA α NB and α NC And the internal force coefficient β of the lowest point A, two side points C and the highest point B of the cross section caused by the three-point load. MA β MB β MC β NA β NB and β NC ;

[0018] Step 1.4: Calculate the standard value M of the bending moment at point A, both sides C, and the uppermost point B of the cross section caused by the self-weight of the pipe. GKA M GKB and M GKC Standard value of axial force N GKA N GKB and N GKC And the standard value M of the bending moment at the lowest point A, the two side points C and the highest point B of the cross section caused by the three-point load. PKA M PKB and M PKC Standard value of axial force N PKA N PKB and N PKC The specific formula is as follows:

[0019] M GKi =α Mi ×G 1K ×r0;

[0020] N GKi =α Ni ×G 1K ;

[0021] M PKi =β Mi ×P×r0;

[0022] N PKi =β Ni ×P;

[0023] Where i is A, B, or C, i.e., M GKi With α Mi For each corresponding M GKA M GKB Or M GKC With α MA α MB or α MC N GKi With α Ni For each corresponding N GKA N GKB or N GKC With α NA α NB or α NC M PKi With β Mi For each corresponding M PKA M PKB Or M PKC With β MA β MB or β MC N PKi With β Ni For each corresponding N PKA N PKBor N PKC With β NA β NB or β NC ;

[0024] Step 1.5: Calculate the standard value of the bending moment M at point A at the bottom of the tube section, points C on both sides, and point B at the top in the experimental state. KA M KB and M KC and the standard value of axial force N KA N KB and N KC The specific formula is as follows;

[0025] M Ki =M GKi +M PKi ;

[0026] N Ki =N GKi +N PKi ;

[0027] Where i is A, B, or C, i.e., M Ki With M GKi and M PKi For each corresponding M KA M KB Or M KC With M GKA M GKB Or M GKC and M PKA M PKB Or M PKC N Ki With N GKi and N PKi For each corresponding N KA N KB or N KC With N GKA N GKB or N GKC and N PKA N PKB or N PKC .

[0028] More preferably, the unit weight γ of the reinforced concrete tube is 26 kN / m³. 3 ;

[0029] In step 1.3, α MA It is 0.239, α MB It is 0.08, α MC The value is -0.091, α NA It is 0.236, α NB It is -0.048, α NC It is 0.25;

[0030] β MA β is 0.318. MB β is 0.318. MC β is -0.182. NA β is 0 NB β is 0 NC It is 0.5.

[0031] The beneficial effects of this invention are:

[0032] The application of this invention can improve design efficiency, reduce design errors, and, while ensuring safety and quality, avoid engineering accidents caused by weak pipe material selection, thus fully leveraging pipeline performance.

[0033] The following will further explain the concept, specific structure, and technical effects of the present invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Attached Figure Description

[0034] Figure 1 The following is a flowchart illustrating the execution of an embodiment of the present invention.

[0035] Figure 2 A flowchart of step 1 in one embodiment of the present invention is shown. Detailed Implementation

[0036] Example

[0037] like Figure 1 The method for analyzing the maximum actual soil cover depth of reinforced concrete drainage pipes, as shown, is characterized by the following steps:

[0038] Step 1: Calculate the standard value M of the bending moment at point A at the bottom of the tube section, points C on both sides, and point B at the top under experimental conditions. KA M KB and M KC and the standard value of axial force N KA N KB and N KC ;

[0039] Step 2: Based on the actual engineering conditions and soil parameters, determine the overburden depth H above the pipe. s As a variable, the internal force design value M' of the drainage pipe project state in the jacking construction method is calculated. di and N' di The depth of soil cover H at the top of the pipe is obtained. s The design value of the internal force M' of the pipe is the independent variable. di and N' di The functional relationship between the dependent and dependent variables;

[0040] Step 3: Adjust H in the functional relationship sThe results of the positive squeeze fitting calculation; make M' di and N' di By approximating the crack load P from the three-point method experiments for Class I, Class II, and Class III pipes according to national standards (i.e., the standard value of internal force under this value), and within the allowable error range in engineering, the corresponding H values ​​for the fitted calculations of Class I, Class II, and Class III pipes are obtained. s The maximum actual overburden depth of the pipe jacking is denoted as H. sMAXI H sMAXII and H sMAXIII .

[0041] This invention improves upon existing technologies and employs computational techniques for automatic calculation. Based on parameters such as soil cohesion, internal friction angle, pipe diameter, and wall thickness in different actual engineering projects, it can specifically determine the maximum overburden depth that Class I, Class II, and Class III pipes can withstand under specific engineering conditions. This effectively avoids engineering accidents caused by weak pipe material selection, and at the same time, fully utilizes pipeline performance while ensuring safety and quality, achieving a safe and economical goal.

[0042] Step 2 can be performed using the internal force calculation method for reinforced concrete drainage pipes in the jacking construction method of the "Technical Specification for Pipe Jacking in Water Supply and Drainage Engineering" CECS246, and the technical calculation method disclosed in Ge Chunhui's "Pipe Jacking Engineering Design and Construction" (first edition, January 2012, pp. 258-264), published by China Architecture & Building Press, with the soil cover depth H above the pipe as the basis. s The design value of the internal force M' of the pipe is the independent variable. di and N' di The function expression for the dependent variable.

[0043] The principle behind step 3 is as follows:

[0044] 1) By adjusting the soil cover depth H above the independent variable pipe s The results of the positive-squeeze fitting calculation are used to calculate the design value of the internal forces of reinforced concrete drainage pipes under the jacking construction method. di '、N di The internal force standard values ​​of the three-point method test conditions of the national standard reinforced concrete drainage pipes (Grade I, Grade II, and Grade III) are respectively approximated to the allowable error range of the project.

[0045] 2) Obtain the fitting calculation results H for each level of national standard reinforced concrete drainage pipe (Level I, Level II, Level III). s H represents the maximum actual backfill depth for the jacking construction method of this level of pipe. sMAXI H sMAXII and H sMAXIII .

[0046] like Figure 2 As shown, in some embodiments, step 1 is specifically as follows:

[0047] Step 1.1: Obtain the nominal inner diameter D0, wall thickness t, and concrete density γ of the drainage pipe to be analyzed.

[0048] Step 1.2: Calculate the pipe's radius r0 and its weight per unit length G. 1k The specific formula is as follows:

[0049] r0 = (D0 + t) / 2;

[0050] G 1k =2πr0×t×γ;

[0051] Step 1.3: Obtain the crack load P in the three-point method experiment, and the internal force coefficients α at the lowest point A, two side points C, and the highest point B of the cross-section caused by the pipe's self-weight. MA α MB α MC α NA α NB and α NC And the internal force coefficient β of the lowest point A, two side points C and the highest point B of the cross section caused by the three-point load. MA β MB β MC β NA β NB and β NC ;

[0052] Step 1.4: Calculate the standard value M of the bending moment at point A, both sides C, and the uppermost point B of the cross section caused by the self-weight of the pipe. GKA M GKB and M GKC Standard value of axial force N GKA N GKB and N GKC And the standard value M of the bending moment at the lowest point A, the two side points C and the highest point B of the cross section caused by the three-point load. PKA M PKB and M PKC Standard value of axial force N PKA N PKB and N PKC The specific formula is as follows:

[0053] M GKi =α Mi ×G 1K ×r0;

[0054] N GKi =α Ni ×G 1K ;

[0055] M PKi =β Mi ×P×r0;

[0056] N PKi =β Ni ×P;

[0057] Where i is A, B, or C, i.e., M GKi With α Mi For each corresponding M GKA M GKB Or M GKC With α MA α MB or α MC N GKi With α Ni For each corresponding N GKA N GKB or N GKC With α NA α NB or α NC M PKi With β Mi For each corresponding M PKA M PKB Or M PKC With β MA β MB or β MC N PKi With β Ni For each corresponding N PKA N PKB or N PKC With β NA β NB or β NC ;

[0058] Step 1.5: Calculate the standard value of the bending moment M at point A at the bottom of the tube section, points C on both sides, and point B at the top in the experimental state. KA M KB and M KC and the standard value of axial force N KA N KB and N KC The specific formula is as follows;

[0059] M Ki =M GKi +M PKi ;

[0060] N Ki =N GKi +N PKi ;

[0061] Where i is A, B, or C, i.e., M Ki With M GKi and M PKi For each corresponding M KAM KB Or M KC With M GKA M GKB Or M GKC and M PKA M PKB Or M PKC N Ki With N GKi and N PKi For each corresponding N KA N KB or N KC With N GKA N GKB or N GKC and N PKA N PKB or N PKC .

[0062] In some embodiments, the unit weight γ of the reinforced concrete tube is 26 kN / m. 3 ;

[0063] In step 1.3, α MA It is 0.239, α MB It is 0.08, α MC The value is -0.091, α NA It is 0.236, α NB It is -0.048, α NC It is 0.25;

[0064] β MA β is 0.318. MB β is 0.318. MC β is -0.182. NA β is 0 NB β is 0 NC It is 0.5.

[0065] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for analyzing the maximum actual cover depth of a reinforced concrete drain pipe, characterized by, The method comprises the following steps: Step 1, Calculate the standard values of the bending moments M KA , M KB and M KC and the standard values of the axial forces N KA , N KB and N KC at the point A under the tube cross section of the experimental state, the points C on both sides and the uppermost point B Step 2, according to the actual engineering conditions and soil parameters, the pipe top soil depth H s As a variable, the internal force design value M' of the pipe jacking construction method is calculated di And N' di , get the function relationship formula with the pipe top soil depth H s As the independent variable, the internal force design value M' di And N' di As the dependent variable Step 3, by adjusting H in the function relationship s , positive calculation of the squeeze fitting calculation results; M' di and N' di , respectively, approach the national standard I, II and III pipe three-point method experimental crack load P, to the engineering allowable error range, the corresponding H s of the fitting calculation results corresponding to I, II and III pipes are obtained as the maximum actual covering depth of the pipe, respectively, H sMAXI , H sMAXII and H sMAXIII .

2. The reinforced concrete sewer maximum actual cover depth analysis method according to claim 1, characterized by, Step 1 is specifically as follows: Step 1.1, obtaining the nominal inner diameter D0, the pipe wall thickness t and the pipe reinforced concrete unit weight γ of the drainage pipe which needs to be analyzed; Step 1.2, Calculate the pipe radius r0and the pipe self-weight per unit length G 1k The specific formula is as follows: r0=(D0+t) / 2; G 1k = 2πr0xt x γ; Step 1.3, obtain the three-point method experimental crack load P, the internal force coefficient α of the lowest point A, the two side points C and the uppermost point B in the section caused by the pipe self weight MA , α MB , α MC , α NA , α NB and α NC , and the internal force coefficient β of the lowest point A, the two side points C and the uppermost point B in the section caused by the three-point load MA , β MB , β MC , β NA , β NB and β NC ; Step 1.4, calculate the bending moment standard values M of the cross section at the lower point A, the two side points C and the uppermost point B caused by the self weight of the pipe GKA , M GKB , and M GKC , the axial force standard values N GKA , N GKB , and N GKC , and the bending moment standard values M of the cross section at the lowermost point A, the two side points C and the uppermost point B caused by the three-point load PKA , M PKB , and M PKC , the axial force standard values N PKA , N PKB , and N PKC , the specific formulas are as follows: M GKi = a Mi x G 1K x r0; N GKi = a Ni x G 1K ; M PKi = β Mi × P × r0; N PKi = β Ni × P; wherein i is A, B or C, i.e. M GKi with a Mi are mutually corresponding M GKA , M GKB or M GKC with a MA , a MB or a MC , N GKi with a Ni are mutually corresponding N GKA , N GKB or N GKC with a NA , a NB or a NC , M PKi with b Mi are mutually corresponding M PKA , M PKB or M PKC with b MA , b MB or b MC , N PKi with b Ni are mutually corresponding N PKA , N PKB or N PKC with b NA , b NB or b NC ; Step 1.5, Calculate the standard value of the bending moment M at point A, the two side points C, and the uppermost point B of the pipe cross section of the experimental state KA M KB and M KC and the standard value of the axial force N KA N KB and N KC , the specific formula is as follows; M Ki = M GKi + M PKi ; N Ki = N GKi + N PKi ; wherein i is A, B or C, i.e. M Ki with M GKi and M PKi are mutually corresponding M KA , M KB or M KC with M GKA , M GKB or M GKC and M PKA , M PKB or M PKC N Ki with N GKi and N PKi are mutually corresponding N KA , N KB or N KC with N GKA , N GKB or N GKC and N PKA , N PKB or N PKC .

3. The reinforced concrete sewer maximum actual cover depth analysis method according to claim 2, characterized by, Pipe reinforced concrete unit weight γ is 26 kN / m 3 ; In step 1.3, a MA = 0.239, a MB = 0.08, a MC = -0.091, a NA = 0.236, a NB = -0.048, a NC = 0.25; β MA is 0.318, β MB is 0.318, β MC is -0.182, β NA is 0, β NB is 0, β NC is 0.5.

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