CN111651945A - Method for acquiring waterproof capacity of double-channel sealing gasket - Google Patents
Method for acquiring waterproof capacity of double-channel sealing gasket Download PDFInfo
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- 238000007789 sealing Methods 0.000 title claims abstract description 261
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Abstract
The invention discloses a method for acquiring the waterproof capacity of a double-channel sealing gasket, which comprises the following steps: calculating the corresponding relation between the residual waterproof ability value of the outer side sealing gasket when the inner side sealing gasket is about to leak and the waterproof ability value of the outer side sealing gasket when the outer side sealing gasket is singly waterproof, wherein the corresponding relation is represented by a reduction coefficient of the residual waterproof ability; determining the total waterproof capacity value of the double-channel sealing gasket, wherein the total waterproof capacity value is the sum of the waterproof capacity value of the inner side sealing gasket and the residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak; the optimization of the total waterproof capacity of the double-channel is realized by adjusting the proportion relation of the waterproof capacities of the inner and outer side sealing gaskets, and the waterproof sealing gaskets are arranged according to the optimization. The invention provides a brand-new method for acquiring the waterproof capability of the sealing gasket, breaks through the calculation theory of the fortification capability of the traditional double-channel sealing gasket, can obviously improve the waterproof safety of the shield tunnel, and has important significance for adapting to high water pressure and prolonging the design service life of the shield tunnel.
Description
Technical Field
The invention belongs to the technical field of shield tunnels, and particularly relates to a method for acquiring waterproof capacity of a double-channel sealing gasket.
Background
In recent thirty years, particularly since the 21 st century, with the construction of urban subways and underwater tunnels in China, the shield method is rapidly developed in China, new records are created once and again on the aspects of tunnel burial depth, diameter and water pressure bearing, and the waterproof design of the shield tunnel is also facing more and more challenges. The shield method tunnel structure is formed by splicing prefabricated pipe pieces, each pipe piece is provided with a waterproof system, and then the waterproof systems are combined into an integral waterproof system. As the waterproof function of the segment joint is the most critical part in the whole waterproof system, the adoption of the double-channel waterproof sealing gasket becomes a mainstream trend more and more along with the increase of water pressure.
The design idea of the waterproof capability of the existing double-channel sealing gasket is as follows: consider that the section of jurisdiction seam is many, difficult exempt from to have weak point because of sealed the pad construction not in place, the sealed pad of two-pass has increased 1 ~ 2 lines of defence than the sealed pad of single pass, can improve waterproof reliability. And think that because each sealed pad all can have the weak point, once groundwater breaks through first line of defence, will be flowed between the sealed pad of twice, and then arouse from the weakest position of the sealed pad of second way and take place the seepage, therefore there is the theory to think that the sealed pad of twice can not improve the waterproof ability of entire system, only is the reserve of a waterproof ability. However, if the respective waterproof capabilities of the inner side sealing gasket and the outer side sealing gasket are used as the overall waterproof capabilities of the two-way sealing gasket, or the sum of the respective waterproof capabilities of the inner side sealing gasket and the outer side sealing gasket is used as the overall waterproof capabilities of the two-way sealing gasket, the overall waterproof capabilities of the two-way sealing gasket are unreasonable, and the waterproof capabilities of the two-way sealing gasket cannot be reflected accurately.
In order to meet the construction requirement of a deeply buried underwater tunnel and guide the design of a high-water-pressure shield tunnel, the key technical problem to be solved is the calculation of the waterproof capacity of the double-channel sealing gasket. When the double-channel sealing gasket is used as a waterproof system of the shield tunnel, the total waterproof capacity of the double-channel sealing gasket can be calculated in advance, and then the reasonable maximum waterproof water pressure is set, so that the waterproof system has great significance on the waterproof safety of the shield tunnel, and theoretical support is provided for the tunnel to develop more deeply.
Disclosure of Invention
Aiming at least one defect or improvement requirement in the prior art, the invention provides a method for acquiring the waterproof capability of a double-channel sealing gasket, and aims to solve the problems that the waterproof capability of the double-channel sealing gasket cannot be quantitatively calculated, so that the waterproof design of a shield tunnel structure is unreasonable, and the waterproof safety of the shield tunnel structure is seriously influenced.
To achieve the above object, according to a first aspect of the present invention, there is provided a method of obtaining a waterproof capability of a two-way gasket, the two-way gasket including an inner side gasket and an outer side gasket, the inner side gasket having a waterproof capability not higher than that of the outer side gasket; the calculation method comprises the following steps:
s1: calculating a corresponding relation between a residual waterproof ability value of the outer side sealing gasket when the inner side sealing gasket is about to leak and a waterproof ability value of the outer side sealing gasket when the outer side sealing gasket is singly waterproof based on a fluid mechanics equation, wherein the corresponding relation is represented by a reduction coefficient of the residual waterproof ability;
s2: determining the total waterproof capacity value of the double-channel sealing gasket, wherein the total waterproof capacity value is the sum of the waterproof capacity value of the inner side sealing gasket and the residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak, and the calculation formula is as follows:
P3＝P2+αP1
F＝P3/P1＝P2/P1+α
wherein, P3The total waterproof capacity value of the double-channel sealing gasket is represented; p2α P representing the waterproof capability of the inner gasket when waterproof alone1The residual waterproof ability value of the outer side sealing gasket when the inner side sealing gasket is about to leak is shown; p1Indicating waterproofing of the outside gasket aloneThe capacity value α represents the reduction coefficient of the residual waterproof capacity obtained by a waterproof test, and F represents the total waterproof coefficient of the double-channel sealing gasket.
Preferably, the obtaining method further includes:
calculating the reduction coefficient of residual waterproof capacity under different experimental working conditions and waterproof capacity values of the outer side sealing gasket and the inner side sealing gasket under the condition of independent waterproof through a double-sealing gasket combined test to generate a mapping relation table; the experimental working conditions comprise the opening amount and the slab staggering amount of the segment joints;
and acquiring the opening amount and the slab staggering amount between the joints of the shield tunnel segments, and calculating the total waterproof energy value of the double-channel sealing gasket according to the corresponding residual waterproof capacity reduction coefficient and the respective waterproof capacity values of the outer side sealing gasket and the inner side sealing gasket which are searched in the mapping relation table according to the opening amount and the slab staggering amount.
Preferably, the obtaining method further includes:
adjusting the waterproof capability P of the inner and outer gaskets when the inner and outer gaskets are independently waterproof by adjusting the physical parameters of the gaskets2、P1And the ratio of the two, so as to maximize the overall waterproofing factor F of the dual gasket;
the physical parameters comprise Poisson's ratio of the corresponding material of the sealing gasket, hole radius of the sealing gasket and elastic modulus of the sealing gasket after compression.
Preferably, the obtaining method further includes:
and configuring a safety factor for representing the aging and stress relaxation of the sealing gasket, and optimizing the total waterproof capacity value of the double-channel sealing gasket according to the safety factor to obtain the final waterproof capacity value of the double-channel sealing gasket.
Preferably, in the above obtaining method, the calculating, based on the fluid mechanics equation, a correspondence between the residual waterproof ability value of the outer gasket when the inner gasket is about to leak and the waterproof ability value of the outer gasket when the outer gasket is waterproof alone is specifically:
acquiring the equivalent diameter and the length of a leakage hole of the outer sealing gasket when leakage is about to occur and the flow speed of water in the leakage hole, and calculating the first flow resistance of the water in the leakage hole of the outer sealing gasket according to a hydrodynamic laminar flow theory; the first flow resistance is used for representing a waterproof capacity value when the outer side sealing gasket is singly waterproof;
acquiring the equivalent diameter and the length of a leakage hole of the outer sealing gasket and the flow speed of water in the leakage hole when the inner sealing gasket is about to leak, and calculating second flow resistance of the water in the leakage hole of the outer sealing gasket according to a hydrodynamic laminar flow theory; the second flow resistance is used for representing the residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak;
and determining the corresponding relation between the residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak and the waterproof capacity value of the outer side sealing gasket when the outer side sealing gasket is singly waterproof according to the first flow resistance and the second flow resistance.
Preferably, in the above obtaining method, the respective waterproof capability values of the outer side sealing gasket and the inner side sealing gasket, and the reduction coefficient of the residual waterproof capability are determined through experiments, and specifically include:
(1) respectively testing the maximum water pressure resistance values of the inner side sealing gasket and the outer side sealing gasket under different experimental working conditions to obtain respective waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket;
(2) under the same experimental working condition, testing the maximum water pressure resistance value of a double-channel sealing gasket consisting of an inner side sealing gasket and an outer side sealing gasket to obtain the total water resistance value of the double-channel sealing gasket;
(3) and carrying out regression analysis on the respective waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket measured under different experimental working conditions and the total waterproof capacity value of the double-channel sealing gasket to obtain the corresponding residual waterproof capacity reduction coefficients under different experimental working conditions.
Preferably, in the above obtaining method, the respective waterproof capability values of the inner side sealing gasket and the outer side sealing gasket and the total waterproof capability value of the dual-channel sealing gasket are tested by respectively adopting a "straight seam" and a "T-shaped seam" waterproof test device, and regression analysis is performed by combining the test results of the "straight seam" and the "T-shaped seam" to calculate the corresponding reduction coefficient of the residual waterproof capability under different experimental conditions.
Preferably, in the above obtaining method, both the inner side sealing gasket and the outer side sealing gasket are ethylene propylene diene monomer rubber sealing gaskets.
In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:
the method for acquiring the waterproof capacity of the double-channel sealing gasket comprises the steps of triggering two factors which influence the waterproof capacity from a leakage hole, a fine leakage hole and contact stress, respectively analyzing the waterproof capacities of an inner sealing gasket and an outer sealing gasket by combining hydrodynamics, determining the relationship among the waterproof capacities of the double-channel sealing gasket, the inner sealing gasket and the outer sealing gasket, and determining the waterproof capacity values of the outer sealing gasket and the inner sealing gasket and the corresponding residual waterproof capacity reduction coefficient under the working condition according to the design working condition of a shield tunnel segment joint, so as to calculate the total waterproof capacity value of the double-channel sealing gasket; the total waterproof capacity value calculated by the method can accurately reflect the waterproof capacity of the shield tunnel waterproof system, the maximum protection water pressure of the shield tunnel is set based on the total waterproof capacity value, leakage can be effectively prevented, and the waterproof safety of the shield tunnel is obviously improved.
Drawings
FIG. 1 is a schematic structural view of a two-way gasket according to an embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating the effect of micro weep holes on water resistance provided by an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a waterproof mechanism of the dual-gasket according to an embodiment of the present invention;
fig. 4 is a design flowchart of a method for acquiring a waterproof capability of a dual-channel gasket according to an embodiment of the present invention.
Fig. 5 is a graph showing a correspondence curve between the total waterproof coefficient of the two-way gasket and the ratio of the waterproof ability values of the inner and outer gaskets when they are individually waterproofed.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
The invention provides a method for acquiring waterproof capacity of a double-channel sealing gasket, which is characterized in that the waterproof capacity of an inner channel sealing gasket and an outer channel sealing gasket is respectively analyzed by combining fluid mechanics from a leakage hole, a fine leakage hole and contact stress which influence the waterproof capacity, and the waterproof capacity of the outer side sealing gasket and the inner side sealing gasket under different working conditions and the corresponding reduction coefficient of the residual waterproof capacity are calculated through a waterproof test, so that the mapping relation between the total waterproof capacity value of the double-channel sealing gasket and the waterproof capacity of the inner side sealing gasket and the outer side sealing gasket is acquired; the waterproof capability of the double-channel sealing gasket adopted in the shield tunnel can be accurately evaluated based on the mapping relation so as to reasonably configure the maximum protection water pressure of the shield tunnel; or the independent waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket are determined by taking the waterproof capacity of the double sealing gasket as the maximum target, and the double sealing gaskets are arranged according to the mode to perform tunnel waterproof, so that the waterproof capacity of the shield tunnel is improved to the maximum extent.
The technical solution of the present invention is explained in detail by specific examples below.
In the method for obtaining the waterproof capability of the two-way sealing gasket provided by the embodiment, the two-way sealing gasket comprises an inner side sealing gasket and an outer side sealing gasket, and the independent waterproof capability of the inner side sealing gasket is not higher than that of the outer side sealing gasket; this is because when the waterproof ability of the inside sealing gasket is higher than the outside sealing gasket, after the outside sealing gasket leaks, along with the increase of the water pressure between the two sealing gaskets, the water pressure of the inside and outside sides of the maximum contact stress point of the outside sealing gasket is higher than the waterproof ability, so that the contact surface of the outside sealing gasket is punctured from the inside and outside sides, and the residual waterproof ability is 0, which is not favorable for the overall waterproof performance and should be avoided.
Fig. 1 is a schematic structural diagram of a two-way gasket according to this embodiment, in which a gasket 1 is an outer-side gasket, a gasket 2 is an inner-side gasket, the outer-side gasket is disposed near a water-facing surface, and a waterproof capability of the inner-side gasket is not higher than that of the outer-side gasket; in the embodiment, the inner side sealing gasket and the outer side sealing gasket are both ethylene propylene diene monomer sealing gaskets; the invention firstly considers two control factors of contact stress and leakage holes, combines hydromechanics, respectively analyzes the waterproof mechanism of the single-channel sealing gasket and the double-channel sealing gasket, determines the hydraulic power and pressure change characteristics of the whole process from the contact of water pressure to the damage of leakage of the inner and outer side sealing gaskets under the waterproof mode of the double-channel sealing gasket, and calculates the relation between the total waterproof capacity of the double-channel sealing gasket and the waterproof capacity of each sealing gasket.
(1) Waterproof mechanism of single-way sealing gasket
The waterproof capacity of the sealing gasket is controlled by two factors, namely the maximum contact stress of each contact surface and the tiny leakage holes of the contact surfaces. When the contact surface state is poor and the leakage holes are large, leakage can occur even if the contact stress is higher than the water pressure; when the contact surface state is good and the leakage hole is small, the waterproof capability is controlled by the contact stress and the leakage hole.
FIG. 2 is a schematic diagram illustrating the effect of micro leak holes on waterproof performance according to the present embodiment; for the waterproof capability of the tiny leakage holes of the contact surface, the analysis is carried out by referring to the idea of rubber sealing in mechanical engineering. When groundwater flows along the seepage hole, viscous resistance can be generated, as long as the viscous resistance in the hole is higher than the pressure difference between the inside and the outside, the seepage amount generated by the viscous resistance can be ignored, and the waterproof effect can be achieved. Only when the water pressure difference causes the leakage amount to exceed the standard, the sealing is considered to be invalid. Actually, when the contact surface state is better, the two factors are mutually influenced, referring to fig. 2, as the water pressure increases, the region with the contact stress at the side of water being smaller than the water pressure gradually opens, and the length of the original tiny leakage hole is shortened, so that the waterproof capability is reduced; when groundwater reaches the maximum contact stress point, if the water resistance in the seepage hole is greater than the waterproof capacity of contact stress, then along with further increase of water pressure, groundwater can break through the maximum contact stress point, make the contact surface of maximum contact stress point dorsal water side also open fast, cause the waterproof capacity of seepage hole to decline sharply, that is to say, contact stress is waterproof and seepage hole water resistance is waterproof almost reaching the limit simultaneously, therefore can adopt the waterproof capacity of seepage hole as the waterproof capacity of design approximately.
(2) Waterproof mechanism of double-channel sealing gasket after leakage of outer sealing gasket
FIG. 3 is a schematic diagram illustrating a waterproof mechanism of the dual-channel gasket provided in this embodiment; as shown in fig. 3, after the double-channel gasket is arranged, after the outside water pressure breaks through the outside gasket, along with the increase of the outside water pressure and the inside water pressure (the water pressure between the double-channel gasket), the contact stress on each contact surface is increased, and the size of the leakage hole is reduced, so that the outside gasket has certain waterproof capability and is marked as residual waterproof capability. When the water pressure of the inner side reaches the waterproof capacity of the inner side sealing gasket, the inner side sealing gasket leaks, and the waterproof capacity of the whole double-channel sealing gasket reaches the limit.
Fig. 4 is a design flowchart of a method for acquiring waterproof capability of a dual-channel gasket provided in this embodiment, and the calculation process provided in this embodiment is described with reference to fig. 4, where the method includes the following steps:
calculating first flow resistance of water in a leakage hole of the outer side sealing gasket when leakage is about to occur, and taking the first flow resistance as a waterproof capacity value of the outer side sealing gasket; calculating a second flow resistance of water in the leakage hole of the outer side sealing gasket when the inner side sealing gasket is about to leak, wherein the second flow resistance is a residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak;
in this condition of the outer gasket at the imminent occurrence of a leak, as shown in FIG. 2, it is assumed that the equivalent diameter of the leak hole in the outer gasket is d1(the diameter is obtained according to the principle that the total resistance of the pipeline with the same cross section is equal to the total resistance of the pipeline with the same cross section because the total length and the diameter of the holes are different), and the length is L1The flow velocity of water in the leakage hole is V1The flow state of the water in the holes is laminar flow. According to the theory of hydrodynamics, the flow resistance of the holes can be obtained as follows:
wherein μ is a viscosity coefficient (Pa/s) and γ is a gravity coefficient (kN/m)3)。
In this condition of the inner seal at the imminent occurrence of a leak, as shown in FIG. 3, it is assumed that the equivalent diameter of the leak hole in the outer seal is d2Length of L2The flow velocity of water in the leakage hole is V2The flow state of the water in the holes is laminar flow. According to the theory of hydrodynamics, the flow resistance of the holes can be obtained as follows:
the symbols in the formula have the same meanings as above and are not described in detail.
Determining a corresponding relation between the residual waterproof capacity value of the outer side sealing gasket and the waterproof capacity value of the outer side sealing gasket according to the first flow resistance and the second flow resistance, wherein the corresponding relation is represented by a residual waterproof capacity reduction coefficient;
determining the total waterproof capacity value of the double-channel sealing gasket, wherein the total waterproof capacity value is the sum of the waterproof capacity value of the inner side sealing gasket and the residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak;
assuming that the waterproof capabilities of the outer side gasket and the inner side gasket are P1、P2The total waterproof capacity of the double-channel sealing gasket is P3；
For the condition that the outer sealing gasket is about to leak, the following conditions are provided:
P1＝hf1(3)
for the condition that the inner sealing gasket is about to leak, the following conditions are provided:
P3-P2＝hf2(4)
substituting formula (1) into formula (3), substituting formula (2) into formula (4), and dividing the left and right sides of formula (3) and formula (4) respectively to obtain:
the allowable leakage amount of the outer side sealing gasket under two working conditions is assumed to be the same, namely:
substituting equation (6) into equation (5) yields:
assuming that the gasket is an elastomer, the displacement of the side wall of the leakage hole under the action of internal pressure is as follows:
wherein ν is Poisson's ratio (EPDM rubber is about 0.47, modified according to the actual engineering value), E is elastic modulus after compression of the gasket (EPDM rubber is about 7.8MPa, modified according to the actual engineering value), a is the radius of the hole, P is the valueiIs the internal pressure.
When the leakage hole of the outside sealing gasket is about to leak in a large scale, the internal pressure can be similar to the external water pressure of the hole, and then:
d1＝(1+0.1885P1)2a (9)
d2＝(1+0.1885P3)2a (10)
substituting equations (9) and (10) into equation (7) can yield:
order:
then: p3＝P2+αP1(13)
α denotes the reduction factor of the residual waterproof ability of the outside gasket, which is used to characterize the residual waterproof ability h of the outside gasketf2Water-proof ability P with outside sealing pad1The corresponding relation between the two;
due to P3≥P1Thus L in general1≥L2I.e. α ≦ 1, and further has P3≤P2+P1Because the factors influencing α are more, the specific value of the compound is determined by a waterproof experiment.
Step four, constructing a mapping relation table among experimental working conditions, the waterproof capability values of the outer side sealing gasket and the inner side sealing gasket and the reduction coefficient of the residual waterproof capability, wherein the experimental working conditions comprise the opening amount and the slab staggering amount of the segment joints;
in this embodiment, the waterproof capability P of the outer side sealing gasket and the inner side sealing gasket under different experimental conditions is determined by the waterproof experimental device1、P2And testing, calculating a reduction coefficient α of residual waterproof capacity, and further establishing a mapping relation table, wherein the waterproof experimental device can adopt a linear seam or T-shaped seam type experimental device, and the specific test process comprises the following steps:
(1) respectively testing the maximum water pressure resistance values of the inner side sealing gasket and the outer side sealing gasket under different experimental working conditions to obtain respective waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket;
in this embodiment, two experimental conditions are designed: the opening amount is 8mm, the staggering amount is 0mm, and the opening amount is 8mm, and the staggering amount is 15 mm; the inner side sealing gasket and the outer side sealing gasket are placed in the testing device separately, water is filled in the sealing gasket, the water pressure is increased by 0.1MPa every five minutes until the sealing gasket seeps water, the maximum water resistance pressure value is tested, and the respective waterproof capabilities of the inner side sealing gasket and the outer side sealing gasket are obtained respectively.
(2) Under the same experimental working condition, testing the maximum water pressure resistance value of a double-channel sealing gasket consisting of an inner side sealing gasket and an outer side sealing gasket to obtain the total water resistance value of the double-channel sealing gasket;
placing the double-channel sealing gasket in a test device according to the same test conditions, filling water in the double-channel sealing gasket, increasing the water pressure by 0.1MPa every five minutes until the sealing gasket seeps water, and testing the maximum water pressure resistance value to obtain the total waterproof capacity of the double-channel sealing gasket;
(3) carrying out regression analysis on the respective waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket measured under different experimental working conditions and the total waterproof capacity value of the double-channel sealing gasket to obtain corresponding residual waterproof capacity reduction coefficients under different experimental working conditions;
table 1 shows the test results of the experimental conditions of the waterproof capability of the dual-channel gasket provided in this embodiment, in which the gasket 1 is an outer-side gasket, and the gasket 3 is an inner-side gasket; the waterproof capability of the sealing gasket 1 is greater than that of the sealing gasket 3; the values in parentheses in the table are the average of the three test values;
TABLE 1 Experimental conditions for waterproof capability of dual-channel sealing gasket
The working condition 6 is limited by the equipment capacity, and the leakage does not occur when the water pressure is loaded to 6.0Mpa, so that the data is non-limit working condition data; regression analysis is performed according to the data in table 1, and the calculation formula of the integral waterproof capacity of the double-channel sealing gasket can be obtained as follows:
the first experimental condition is as follows: opening 8mm, staggering 0 mm:
P3>0.74P1+P2(14)
the experimental conditions are as follows: opening an 8mm dislocation table by 15 mm:
P3＝0.53P1+P2(15)
since waterproofing of segment joints requires consideration of adverse conditions of proper opening and dislocation, the design waterproofing ability is preferably calculated according to the formula (b).
As a preferred example, in the present embodiment, the respective waterproof capabilities of the inner side sealing gasket and the outer side sealing gasket and the total waterproof capability of the dual-way sealing gasket are tested by using the "straight seam" and "T-seam" waterproof test apparatuses, respectively, and regression analysis is performed by combining the test results of the "straight seam" and the "T-seam" to calculate the reduction coefficient of the residual waterproof capability corresponding to different experimental conditions.
As a specific application of the scheme, on the basis of determining the calculation method of the total waterproof capacity value of the double-channel sealing gasket and the mapping relation table, the actual waterproof capacity value can be calculated according to the setting condition of the shield tunnel waterproof system, so that the waterproof pressure is reasonably set, and the waterproof safety is improved; specifically, the method comprises the following steps:
under the condition that the opening amount and the slab staggering amount between the joints of the shield tunnel segments are known, acquiring respective waterproof capacity values of the outer side sealing gasket and the inner side sealing gasket and corresponding residual waterproof capacity reduction coefficients under the current experimental working condition according to the mapping relation table created in the fourth step, and calculating the total waterproof capacity value of the double-channel sealing gasket;
if the opening amount and the slab staggering amount between the segment joints of a certain tunnel are known, the respective waterproof capacities of the outer side sealing gasket and the inner side sealing gasket and the corresponding reduction coefficient of the residual waterproof capacity can be obtained, and then the total waterproof capacity of the double-channel sealing gasket can be calculated according to a formula (13).
The waterproof pressure of the double-channel sealing gasket is higher than that of the single-channel sealing gasket in waterproof lifting rate: t ═ P2+αP1) /P1＝P2/P1+α。
The total waterproof ability value of the above two-way sealing gasket is calculated without considering the aging and stress relaxation phenomena of the sealing gasket, and in the practical application process, the sealing gasket can affect the total waterproof ability after aging and stress relaxation, therefore, in order to more accurately reflect the total waterproof ability of the two-way sealing gasket, the embodiment adds the influence factors of aging and stress relaxation into the above calculation formula, and the calculation formula for obtaining the final waterproof ability of the two-way sealing gasket is as follows:
Pw＝(P2+αP1)/K (16)
in the formula, PwFor final waterproofing of the double-seal(ii) a capability; p1、P2The waterproof capacity of the outer side sealing gasket and the waterproof capacity of the inner side sealing gasket are not considered in aging and stress relaxation, α is a reduction coefficient of the residual waterproof capacity of the outer side sealing gasket, K is a safety coefficient considering aging and stress relaxation, and K is 2-3.
Taking a double-channel waterproof sealing gasket adopted by a certain tunnel in China as an example, the waterproof capability finally determined by adopting the method is as follows:
Pw＝(P2+0.5P1)/K
to obtain the maximum water pressure PwThe waterproof pressure of the tunnel is increased from 0.8MPa to 1.5MPa at present in China because of (2.2+0.5 x 3.1)/2.5 x 1.5 MPa.
As another specific application of the present invention, on the basis of determining the mapping relationship between the total waterproof ability value of the two-way gasket and the waterproof ability values of the inner and outer gaskets when they are individually waterproofed, the waterproof ability value P of the inner and outer gaskets when they are individually waterproofed is adjusted by adjusting the physical parameters of the gaskets2、P1And the ratio of the two, so as to maximize the overall waterproofing factor F of the dual gasket, wherein:
F＝P3/P1＝P2/P1+α (17)
FIG. 5 is a graph showing a correspondence between the total waterproof coefficient of the two-way gasket and the ratio of the waterproof ability values of the inner gasket and the outer gasket when they are individually waterproofed; as can be seen from FIG. 5, by pairing P2、P1The ratio of (A) is optimized, so that the total waterproof coefficient F can be maximized; the physical parameters of the sealing gasket comprise Poisson ratio v of the corresponding material of the sealing gasket, the hole radius a of the sealing gasket, the elastic modulus E of the sealing gasket after compression and the like, and the physical parameters can influence the independent waterproof capacity value of the inner/outer sealing gasket. The design goal of the scheme is to maximize the total waterproof coefficient F, and the double-sealing gasket is arranged according to the waterproof capacity value and the position relation of the inner-side sealing gasket and the outer-side sealing gasket when the total waterproof coefficient F is maximized, so that the total waterproof capacity value P of the double-sealing gasket can be increased3Realize the double-channel waterproof assemblyAnd optimizing the waterproof capability.
It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (7)
1. The method for acquiring the waterproof capacity of the double-channel sealing gasket is characterized in that the double-channel sealing gasket comprises an inner side sealing gasket and an outer side sealing gasket, and the waterproof capacity value of the inner side sealing gasket is not higher than that of the outer side sealing gasket; the method comprises the following steps:
s1: calculating a corresponding relation between a residual waterproof ability value of the outer side sealing gasket when the inner side sealing gasket is about to leak and a waterproof ability value of the outer side sealing gasket when the outer side sealing gasket is singly waterproof based on a fluid mechanics equation, wherein the corresponding relation is represented by a reduction coefficient of the residual waterproof ability;
s2: determining the total waterproof capacity value of the double-channel sealing gasket, wherein the total waterproof capacity value is the sum of the waterproof capacity value of the inner side sealing gasket and the residual waterproof capacity value of the outer side sealing gasket when the inner side sealing gasket is about to leak, and the calculation formula is as follows:
P3＝P2+αP1
F＝P3/P1＝P2/P1+α
wherein, P3The total waterproof capacity value of the double-channel sealing gasket is represented; p2α P representing the waterproof capability of the inner gasket when waterproof alone1The residual waterproof ability value of the outer side sealing gasket when the inner side sealing gasket is about to leak is shown; p1The waterproof capacity value of the outer side sealing gasket during independent waterproof is shown, α shows the reduction coefficient of the residual waterproof capacity obtained through a waterproof test, and F shows the total waterproof coefficient of the double-channel sealing gasket.
2. The method for obtaining the waterproof capability of a two-way gasket according to claim 1, further comprising:
calculating the reduction coefficient of residual waterproof capacity under different experimental working conditions and waterproof capacity values of the outer side sealing gasket and the inner side sealing gasket under the condition of independent waterproof through a double-sealing gasket combined test to generate a mapping relation table; the experimental working conditions comprise the opening amount and the slab staggering amount of the segment joints;
and acquiring the opening amount and the slab staggering amount between the joints of the shield tunnel segments, and calculating the total waterproof energy value of the double-channel sealing gasket according to the corresponding residual waterproof capacity reduction coefficient and the respective waterproof capacity values of the outer side sealing gasket and the inner side sealing gasket which are searched in the mapping relation table according to the opening amount and the slab staggering amount.
3. The method for obtaining the waterproof capability of a two-way gasket according to claim 1, further comprising:
adjusting the waterproof capability P of the inner and outer gaskets when the inner and outer gaskets are independently waterproof by adjusting the physical parameters of the gaskets2、P1And the ratio of the two, so as to maximize the overall waterproofing factor F of the dual gasket;
the physical parameters comprise Poisson's ratio of the corresponding material of the sealing gasket, hole radius of the sealing gasket and elastic modulus of the sealing gasket after compression.
4. The method for obtaining the waterproof capability of a two-way gasket according to claim 1, further comprising:
and configuring a safety factor for representing the aging and stress relaxation of the sealing gasket, and optimizing the total waterproof capacity value of the double-channel sealing gasket according to the safety factor to obtain the final waterproof capacity value of the double-channel sealing gasket.
5. The method for acquiring waterproof capability of a dual gasket according to claim 2, wherein the process of establishing the mapping relationship table specifically includes:
respectively testing the maximum water pressure resistance values of the inner side sealing gasket and the outer side sealing gasket under different experimental working conditions to obtain respective waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket;
under the same experimental working condition, testing the maximum water pressure resistance value of a double-channel sealing gasket consisting of an inner side sealing gasket and an outer side sealing gasket to obtain the total water resistance value of the double-channel sealing gasket;
and carrying out regression analysis on the respective waterproof capacity values of the inner side sealing gasket and the outer side sealing gasket measured under different experimental working conditions and the total waterproof capacity value of the double-channel sealing gasket to obtain the corresponding residual waterproof capacity reduction coefficients under different experimental working conditions.
6. The method for acquiring the waterproof capability of the dual-channel sealing gasket according to claim 5, wherein the waterproof capability values of the inner sealing gasket and the outer sealing gasket and the total waterproof capability value of the dual-channel sealing gasket are respectively tested by adopting a 'straight seam' and 'T-shaped seam' waterproof test device, and regression analysis is performed by combining the test results of the 'straight seam' and the 'T-shaped seam' to calculate the corresponding reduction coefficient of the residual waterproof capability under different experimental conditions.
7. The method for obtaining the waterproof capability of the dual gasket as recited in claim 1, wherein the inner gasket and the outer gasket are both ethylene propylene diene monomer gaskets.
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