Earth pressure balance shield foam system, working method and calculation method

Abstract

The present invention discloses an earth pressure balance shield foam system, including a solution generating unit and a gas transmission unit, wherein the output pipelines of the solution generating unit and the gas transmission unit are both connected to a foam generator, and the foam generator generates foam required for improving the slag of the earth pressure balance shield. The present invention has a reasonable structure, and the normal operation of the system is ensured by an overflow section. The solution and the gas enter the foam generator in two ways, wherein the solution branch is provided with a mixing box to ensure sufficient mixing of the original liquid and water, and the gas circuit is provided with a condenser and a pressure reducing valve to ensure the safety of the gas circuit. The working process of the whole system is reasonable, and the control logic is clear, which ensures the safety and normal operation of the system. A gas pressure sensor is provided between the electric switch and the gas flow sensor. The calculation method is mainly for the semi-automatic mode and the fully automatic mode. The calculation methods of the two injection modes are novel, and the calculated gas volume is reasonable and accurate, which provides a guarantee for the normal operation of the system.

Description

Technical Field

[0001] The invention relates to earth pressure balance shield construction, and in particular to an earth pressure balance shield foam system, a working method and a calculation method. Background Art

[0002] The shield method is widely used in subways in major cities due to its advantages of safety, reliability, speed, economy and environmental protection. Earth pressure balance shield is increasingly used in urban subway tunnel construction.

[0003] The improvement of soil in the earth pressure balance shield plays a very important role in shield construction. The main materials for improving soil are foam, bentonite slurry, polymer aqueous solution and water. Foam plays an important role in the improvement of soil in the earth pressure balance shield due to its advantages such as high foaming rate, good lubricity, low cost and convenient operation. It is widely used in various rock formations such as silt formation, mudstone formation, sand formation and gravel formation.

[0004] Foam systems generally have three injection modes: manual, semi-automatic, and fully automatic. At present, the semi-automatic injection mode is generally adopted. However, in the semi-automatic foam injection mode, the calculation methods of setting the gas volume in the foam system are different for each shield manufacturer, and no consensus can be reached. After the parameters of some shield foam systems are set, the calculated gas volume is very large, resulting in adverse consequences such as gushing and over-squareness during earth pressure balance shield tunneling. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an earth pressure balance shield foam system, a working method and a calculation method. The earth pressure balance shield foam system has a reasonable structure and a clear control logic of the entire system, which ensures the safety and normal operation of the system. The gas volume calculated by the calculation method is reasonable, which provides a guarantee for the normal operation of the system.

[0006] The objective of the present invention is achieved through the following technical solutions:

[0007] The earth pressure balance shield foam system includes a solution generating unit and a gas transmission unit, wherein the output pipelines of the solution generating unit and the gas transmission unit are both connected to a foam generator, and the foam generator generates foam required for improving the earth pressure balance shield slag;

[0008] The foam generator is connected to the foam pipe, and the foam in the foam pipe must be able to be sprayed in front of the cutter disc;

[0009] The solution generating unit comprises a container for containing a foaming agent raw liquid, a raw liquid pipeline and a water inlet pipeline, wherein the raw liquid pipeline is connected to the container, and the end of the water inlet pipeline is a water inlet; the raw liquid pipeline and the water inlet pipeline are respectively connected to a mixing box or the raw liquid pipeline and the water inlet pipeline are connected to a tee, and a confluence pipeline is arranged between the tee and the mixing box; a solution pipeline is arranged between the mixing box and the foam generator;

[0010] The gas transmission unit includes an air intake pipe, a condenser, a pressure reducing valve, a barometer, a gas pressure sensor and an electric switch; the air intake pipe includes an air intake section 1 and an air intake section 2, and the barometer includes a first barometer and a second barometer; the air intake section 1 is provided with a condenser, a pressure reducing valve and a first barometer in sequence along the air intake direction, and the air intake section 2 is provided with a gas pressure sensor, an electric switch (a second electric switch) and a second barometer in sequence along the air intake direction; the air intake section 2 is connected to a foam generator.

[0011] As a preferred embodiment, the container for holding the foaming agent raw liquid is a storage tank, and the bottom of the storage tank is connected to the raw liquid pipeline.

[0012] As a preferred embodiment, the raw liquid pipeline includes four sections, which are respectively a first raw liquid pipe section, a second raw liquid pipe section, a third raw liquid pipe section and a fourth raw liquid pipe section; the second raw liquid pipe section and the third raw liquid pipe section are arranged between the first raw liquid pipe section and the fourth raw liquid pipe section, and the second raw liquid pipe section and the third raw liquid pipe section are arranged in parallel.

[0013] As a preferred embodiment, the second raw liquid pipe section is set as an overflow section, and the first safety overflow valve is installed on the second raw liquid pipe section; the first variable frequency screw pump is installed on the third raw liquid pipe section; the first liquid level sensor is also installed on the third raw liquid pipe section; the first liquid flow sensor is arranged on the third raw liquid pipe section, and the first liquid level sensor, the first variable frequency screw pump and the first liquid flow sensor are arranged in sequence in the flow direction of the raw liquid.

[0014] As a preferred embodiment, a second liquid level sensor, a third liquid level sensor and a fourth liquid level sensor are installed on the mixing box.

[0015] As a preferred embodiment, a second variable frequency screw pump and a third liquid flow sensor are arranged on the solution pipeline. A second overflow section is connected in parallel on both sides of the second variable frequency screw pump, and a second safety overflow valve is arranged on the second overflow section.

[0016] The working method of the earth pressure balance shield foam system includes the following steps:

[0017] The foaming agent stock solution in the storage tank enters the inlet of the first variable frequency screw pump. After the first variable frequency screw pump is started, the high-pressure liquid is pumped out from the outlet of the first variable frequency screw pump, mixed with the water from the high-pressure water inlet through the first electric switch through the first check valve, and enters the mixing box;

[0018] The order of generating foam is as follows: the foam agent mixture in the mixing box enters the foam generator through the second stop valve (the first stop valve is installed on the first raw liquid pipe section), the second variable frequency screw pump, the second one-way valve, and the third stop valve; the high-pressure gas enters the foam generator through the air inlet, the fifth stop valve, the condenser, the pressure reducer, the second electric switch, the fourth one-way valve, and the sixth stop valve; the high-pressure foam agent mixture and the high-pressure gas generate foam in the foam generator, and after passing through the foam inspection window and the third one-way valve, the slag in front of the cutter disc is improved. The working method of the earth pressure balance shield foam system includes:

[0019] (1) When there is no foaming agent liquid in the storage tank, the first liquid level sensor displays empty, and the first variable frequency screw pump is not allowed to start;

[0020] (2) When the outlet pressure of the first variable frequency screw pump exceeds the safety pressure of the pump, the first safety relief valve opens and overflows back to the storage tank;

[0021] (3) When the first variable frequency screw pump is started, the required water flow rate can be calculated according to the flow rate of the first liquid flow sensor and the foaming agent concentration value, and the opening of the first electric switch is adjusted according to the value of the second liquid flow sensor to achieve the required water flow value;

[0022] (4) Three liquid level sensors are arranged in the mixing box: the second liquid level sensor, the third liquid level sensor and the fourth liquid level sensor; when the second liquid level sensor is powered on, it indicates that the liquid in the mixing box is full and the first variable frequency screw pump is shut down; when the third liquid level sensor loses power, it indicates that the liquid in the mixing box is almost used up and the first variable frequency screw pump is started; when the fourth liquid level sensor loses power, it indicates that the liquid in the mixing box is used up and the second variable frequency screw pump arranged on the solution pipeline is shut down and is not allowed to start;

[0023] (5) When the outlet liquid pressure of the second variable frequency screw pump exceeds the safety pressure of the pump, the second safety relief valve opens to overflow;

[0024] (6) The rotation speed of the second variable frequency screw pump can be adjusted in real time according to the flow value of the third liquid flow sensor to achieve the desired liquid flow.

[0025] (7) The opening of the second electric switch can be adjusted in real time according to the flow value of the gas flow sensor to achieve the desired gas flow;

[0026] (8) The pressure value of the foam pressure sensor can be used to determine whether the foam pipeline is blocked.

[0027] The calculation method of the foam system of the earth pressure balance shield includes: the foam system includes three injection modes: manual, semi-automatic and fully automatic;

[0028] In the manual injection mode, the flow rate of the foaming agent mixture is controlled by adjusting the rotation speed of the second variable frequency screw pump, and the gas flow rate is controlled by adjusting the opening of the second electric switch;

[0029] In semi-automatic mode:

[0030] A gas pressure sensor is set between the gas flow sensor on the second intake section and the second electric switch to measure the gas pressure value here; the gas pressure of the gas pressure sensor is set to P Gas ;

[0031] Assume the soil tank pressure is P e , the foaming rate is x, the foaming agent mixture is QLiquid, the gas volume is QGas, and the amount of foam generated is Q;

[0032] Calculation of the amount of foaming agent mixed liquid: QLiquid = Q / x;

[0033] The amount of gas required for foam can be accurately derived from the relationship between gas pressure and volume:

[0034] Semi-automatic mode: QGas=Q×(1-1 / x)×P e / P Gas

[0035] In full automatic mode:

[0036] Assume the shield excavation face area is A, the excavation speed is v, the foam injection rate is y, and the total amount of foam required is Q 总 ;

[0037] Calculate the total foam volume Q required by the shield tunneling speed 总 =A×v×y, then calculate the amount of foam required for each foam pipe according to the proportion of foam in each foam pipe, and finally calculate the amount of foam required for each foam pipe according to Q Liquid =Q / x to calculate the amount of foaming agent mixture, and according to Q Gas =Q×(1-1 / x)×P e / P Gas Calculate the amount of gas.

[0038] The beneficial effects of the present invention are as follows: the present invention provides an earth pressure balance shield foam system, working method and calculation method. The structure of the entire foam system is reasonable, and the normal operation of the system is guaranteed by the overflow section. The solution and gas enter the foam generator in two ways, wherein the solution branch is provided with a mixing box to ensure sufficient mixing of the original liquid and water, and the gas circuit is provided with a condenser and a pressure reducing valve to ensure the safety of the gas circuit. The working process of the entire system is reasonable, and the control logic is clear, which ensures the safety and normal operation of the system. The calculation method is mainly for the semi-automatic mode and the fully automatic mode. The calculation methods of the two injection modes are novel, which provide guarantee for the normal operation of the system.

[0039] In addition, a gas pressure sensor is added between the gas flow sensor and the second electric switch to accurately calculate the required gas volume, and a control method for the minimum flow rate of the foaming agent in the full-automatic mode is proposed, which solves the problem that the calculation method of the gas volume of the foam system is inaccurate and the full-automatic foam injection mode cannot be used. The present invention sets a gas pressure sensor on the gas pipeline to accurately calculate the gas volume required to generate foam, so as to generate excellent foam. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0041] Figure 1 This is a schematic diagram of the structure of the earth pressure balance shield foam system;

[0042] Figure 2 for Figure 1 A schematic diagram of the structure of part A;

[0043] Figure 3 for Figure 1 Schematic diagram of the structure of part B;

[0044] Figure 4 for Figure 1 Schematic diagram of the C part structure;

[0045] Figure 5 for Figure 1 Schematic diagram of the D part structure;

[0046] In the figure, 1-storage tank, 2-first stop valve, 3-first liquid level sensor, 4-first variable frequency screw pump, 5-first safety overflow valve, 6-first liquid flow sensor, 7-second liquid flow sensor, 8-first check valve, 9-first electric switch, 10-mixing box, 11-second liquid level sensor, 12-third liquid level sensor, 13-fourth liquid level sensor, 14-second stop valve, 15-second variable frequency screw pump, 16-second safety overflow valve, 17-second check valve, 18-first Three stop valves, 19-third liquid flow sensor, 20-pressure gauge, 21-foam generator, 22-foam inspection window, 23-foam pressure sensor, 24-third one-way valve, 25-fourth stop valve, 26-fifth stop valve, 27-third barometer, 28-condenser, 29-pressure reducer, 30-first barometer, 31-gas flow sensor, 32-second electric switch, 33-second barometer, 34-fourth one-way valve, 35-sixth stop valve, 36-gas pressure sensor. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0049] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0050] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] In the present invention, unless otherwise clearly specified and limited, if a first feature exists above or below a second feature, it may include that the first and second features are in direct contact, or it may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature is above, above and above the second feature, including that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. If the first feature exists below, below and below the second feature, it includes that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0052] Embodiment 1

[0053] like Figure 1-Figure 5 As shown, the earth pressure balance shield foam system includes a solution generating unit and a gas transmission unit, the output pipelines of the solution generating unit and the gas transmission unit are both connected to the foam generator 21, and the foam generator 21 generates the foam required for providing the slag improvement;

[0054] The foam generator 21 is connected to the foam pipe, and the foam in the foam pipe needs to be able to be sprayed in front of the cutter disc; further, the foam in the foam pipe is directly and evenly sprayed onto the palm surface in front of the cutter disc through the rotary joint, pipeline and multiple nozzles in front of the cutter disc, so as to improve the debris cut by the cutter disc; the improved debris enters the soil compartment through the cutter disc opening and is finally output through the screw conveyor.

[0055] The solution generating unit comprises a container for containing a foaming agent raw liquid, a raw liquid pipeline and a water inlet pipeline, the raw liquid pipeline is connected to the container, and the end of the water inlet pipeline is a water inlet; the raw liquid pipeline and the water inlet pipeline are respectively connected to the mixing box 10 or the raw liquid pipeline and the water inlet pipeline are connected to a tee, and a confluence pipeline is arranged between the tee and the mixing box 10; a solution pipeline is arranged between the mixing box 10 and the foam generator 21;

[0056] The gas transmission unit includes an air intake pipe, a condenser 28, a pressure reducing valve (pressure reducer 29), a barometer, a gas pressure sensor 36 and a second electric switch 32; the air intake pipe includes an air intake section 1 and an air intake section 2, and the barometer includes a first barometer 30 and a second barometer 33; the air intake section 1 is provided with a condenser 28, a pressure reducer 29 and a first barometer 30 in sequence along the air intake direction, and the air intake section 2 is provided with a gas pressure sensor 36, a second electric switch 32 and a second barometer 33 in sequence along the air intake direction; the air intake section 2 is connected to the foam generator 21.

[0057] Embodiment 2

[0058] In order to achieve better storage, the container for holding the foaming agent raw liquid is a storage tank 1, and the bottom of the storage tank 1 is connected to the raw liquid pipeline. The connection position of the raw liquid pipeline and the storage tank 1 can make the raw liquid in the storage tank 1 flow out completely under the action of gravity. The installation position of the storage tank 1 is higher than the installation position of the first variable frequency screw pump 4. The installation position of the mixing box 10 is higher than the installation position of the second variable frequency screw pump 15. This arrangement allows the liquid to flow to the inlet of the variable frequency screw pump under the action of gravity.

[0059] Embodiment 3

[0060] The raw liquid pipeline includes four sections, which are the first raw liquid pipe section, the second raw liquid pipe section, the third raw liquid pipe section and the fourth raw liquid pipe section; the second raw liquid pipe section and the third raw liquid pipe section are arranged between the first raw liquid pipe section and the fourth raw liquid pipe section, and the second raw liquid pipe section and the third raw liquid pipe section are arranged in parallel.

[0061] The second raw liquid pipe section is set as an overflow section, and the first safety overflow valve 5 is installed on the second raw liquid pipe section. The first safety overflow valve 5 can ensure the normal operation of the raw liquid pipeline and avoid the situation where the first variable frequency screw pump 4 is damaged due to excessive pressure. When the outlet pressure of the first variable frequency screw pump 4 exceeds the safety pressure of the pump, the first safety overflow valve 5 opens and overflows back to the storage tank 1.

[0062] In order to provide high-pressure raw liquid, a first variable frequency screw pump 4 is installed on the third raw liquid pipe section.

[0063] Embodiment 4

[0064] On the basis of the third embodiment, a first liquid level sensor 3 is further installed on the third raw liquid pipe section. A first liquid flow sensor 6 is arranged on the third raw liquid pipe section, and the first liquid level sensor 3, the first variable frequency screw pump 4 and the first liquid flow sensor 6 are arranged in sequence in the flow direction of the raw liquid. The liquid level of the third raw liquid or the storage tank 1 can be monitored by the first liquid level sensor 3. For example, when there is no raw liquid in the storage tank 1, the first liquid level sensor 3 loses power, and the controller can send a display signal (such as the number 0) to the display indicating that there is no raw liquid in the storage tank 1 after receiving the signal from the first liquid level sensor 3. After the first liquid level sensor 3 loses power, the first variable frequency screw pump 4 can also be turned off by the controller, or the operator can replenish the raw liquid in the storage tank 1 after obtaining the signal that there is no liquid in the storage tank 1. The flow of the third raw liquid pipe section can be obtained by the first liquid flow sensor 6.

[0065] Embodiment 5

[0066] A second liquid level sensor 11, a third liquid level sensor 12 and a fourth liquid level sensor 13 are installed on the mixing box 10; the second liquid level sensor 11 is used to detect whether the liquid in the mixing box 10 is full, the third liquid level sensor 12 is used to detect whether the liquid in the mixing box 10 reaches a critical value, which can be 10%-30% of the height or volume of the mixing box 10, and the fourth liquid level sensor 13 is used to detect whether the liquid in the mixing box 10 is empty.

[0067] The solution pipeline is provided with a second variable frequency screw pump 15 and a third liquid flow sensor 19. The second overflow section is connected in parallel on both sides of the second variable frequency screw pump 15, and the second overflow section is provided with a second safety overflow valve 16 to ensure the normal operation of the solution pipeline.

[0068] Embodiment 6

[0069] like Figure 1-Figure 5 , the devices involved in this embodiment are sorted out as follows:

[0070] The stop valves include: a first stop valve 2, a second stop valve 14, a third stop valve 18, a fourth stop valve 25, a fifth stop valve 26 and a sixth stop valve 35. The first stop valve 2 is installed on the first raw liquid pipe section. The second stop valve 14 is installed on the solution pipeline near the mixing box 10. The third stop valve 18 is installed on the solution pipeline near the foam generator 21. The fourth stop valve 25 is installed on the foam pipeline. The fifth stop valve 26 is installed on the first air intake section near the air inlet. The sixth stop valve 35 is installed on the second air intake section near the foam generator 21.

[0071] The liquid level sensor includes: a first liquid level sensor 3, a second liquid level sensor 11, a third liquid level sensor 12 and a fourth liquid level sensor 13. The first liquid level sensor 3 is arranged on the third raw liquid pipe section. The second liquid level sensor 11, the third liquid level sensor 12 and the fourth liquid level sensor 13 are arranged on the mixing box 10 for detecting the liquid level.

[0072] The variable frequency screw pump comprises: a first variable frequency screw pump 4 and a second variable frequency screw pump 15. The first variable frequency screw pump 4 is installed on the third raw liquid pipe section; the second variable frequency screw pump 15 is arranged on the solution pipeline.

[0073] The safety relief valve comprises: a first safety relief valve 5 and a second safety relief valve 16. The first safety relief valve 5 is installed on the second raw liquid pipe section; the second safety relief valve 16 is arranged on the second overflow section.

[0074] The liquid flow sensor includes: a first liquid flow sensor 6, a second liquid flow sensor 7 and a third liquid flow sensor 19. The first liquid flow sensor 6 is arranged on the third raw liquid pipe section; the second liquid flow sensor 7 is arranged on the water inlet pipe near the water inlet; and the third liquid flow sensor 19 is arranged on the solution pipe.

[0075] Pressure gauge 20 : The pressure gauge 20 is arranged on the solution pipe section between the third liquid flow sensor 19 and the foam generator 21 .

[0076] The barometer includes: a first barometer 30, a second barometer 33 and a third barometer 27. The first barometer 30 is arranged on the first air intake section. The second barometer 33 is arranged on the second air intake section. The third barometer 27 is installed between the fifth stop valve 26 and the condenser 28.

[0077] The electric switch includes: a first electric switch 9 and a second electric switch 32. The first electric switch 9 is arranged on the water inlet pipe; the second electric switch 32 is installed on the second air inlet section.

[0078] The one-way valve includes: a first one-way valve 8, a second one-way valve 17, a third one-way valve 24 and a fourth one-way valve 34. The first one-way valve 8 is installed on the fourth raw liquid pipe section; the second one-way valve 17 is installed on the solution pipeline and is located after the second variable frequency screw pump 15; the third one-way valve 24 is arranged on the foam pipeline and is located between the foam pressure sensor 23 and the fourth stop valve 25; the fourth one-way valve 34 is arranged on the second air intake section and is located between the second air pressure gauge 33 and the sixth stop valve 35.

[0079] This embodiment has set installation restrictions for most of the devices. Together with other embodiments, it can form a better earth pressure balance shield foam system. The various components are reasonably arranged to facilitate control and adjustment.

[0080] Embodiment 7

[0081] The working method of the earth pressure balance shield foam system includes the following steps:

[0082] After the first variable frequency screw pump 4 is started, the foaming agent liquid in the storage tank 1 enters the inlet of the first variable frequency screw pump 4, and the high-pressure liquid is pumped out from the outlet of the first variable frequency screw pump 4, passes through the first check valve 8 and is mixed with the high-pressure water from the high-pressure water inlet through the first electric switch 9, and enters the mixing box 10;

[0083] The order of generating foam is as follows: the foaming agent mixed liquid in the mixing box 10 enters the foam generator 21 through the second stop valve 14 (the first stop valve 2 is installed on the first raw liquid pipe section), the second variable frequency screw pump 15, the second one-way valve 17, the third stop valve 18, the third liquid flow sensor 19, and the pressure gauge 20; the high-pressure gas enters the foam generator 21 through the air inlet, the fifth stop valve 26, the third air pressure gauge 27, the condenser 28, the pressure reducer 29, the first air pressure gauge 30, the gas flow sensor 31, the second electric switch 32, the second air pressure gauge 33, the fourth one-way valve 34, and the sixth stop valve 35; the high-pressure foaming agent mixed liquid and the high-pressure gas generate foam in the foam generator 21, and are sprayed to the front of the cutter disc through the foam inspection window 22, the foam pressure sensor 23, the third one-way valve 24, and the rotary joint to improve the slag in front of the cutter disc.

[0084] Embodiment 8

[0085] The working method of the earth pressure balance shield foam system includes:

[0086] (1) When there is no foaming agent concentrate in the storage tank 1, the first liquid level sensor 3 displays empty, and the first variable frequency screw pump 4 is not allowed to start.

[0087] (2) When the outlet pressure of the first variable frequency screw pump 4 exceeds the safety pressure of the pump, the first safety relief valve 5 opens to overflow back to the storage tank 1.

[0088] (3) When the first variable frequency screw pump 4 is started, the required water flow rate can be calculated according to the flow rate of the first liquid flow sensor 6 and the input foaming agent concentration value, and the opening of the first electric switch 9 is adjusted according to the value of the second liquid flow sensor 7 to achieve the required water flow value.

[0089] (4) Three liquid level sensors are arranged in the mixing box 10: a second liquid level sensor 11, a third liquid level sensor 12 and a fourth liquid level sensor 13; when the second liquid level sensor 11 is powered on, it indicates that the mixing box 10 is full of liquid, and the first variable frequency screw pump 4 is shut down; when the third liquid level sensor 12 is powered off, it indicates that the liquid in the mixing box 10 is almost used up, and the first variable frequency screw pump 4 is started; when the fourth liquid level sensor 13 is powered off, it indicates that the liquid in the mixing box 10 is used up, and the second variable frequency screw pump 15 arranged on the solution pipeline is shut down and is not allowed to start.

[0090] (5) When the outlet liquid pressure of the second variable frequency screw pump 15 exceeds the safety pressure of the pump, the second safety relief valve 16 opens to overflow.

[0091] (6) According to the shield foam parameter setting, the required liquid flow rate of each foam pipeline can be calculated. According to the flow value of the third liquid flow sensor 19, the speed of the second variable frequency screw pump 15 can be adjusted in real time to achieve the required liquid flow rate.

[0092] (7) According to the shield foam parameter setting, the required gas flow rate of each foam pipeline can be calculated. According to the flow value of the gas flow sensor 31, the opening of the second electric switch 32 can be adjusted in real time to achieve the required gas flow rate.

[0093] (8) The effect of the generated foam can be checked through the foam inspection window 22 or by opening the fourth stop valve 25, and the foam-related parameter settings can be appropriately adjusted according to the foam effect.

[0094] (9) Whether the foam pipeline is blocked can be determined by the pressure value of the foam pressure sensor 23.

[0095] (10) The one-way valve prevents the reverse flow of the relevant media. Each stop valve is opened or closed when it needs to be inspected or maintained. Each pressure gauge can observe the pressure in real time.

[0096] (11) The number of foam pipes for each shield machine should be designed based on factors such as the shield excavation area and the flow rate of each foam pipe. Figure 1 and Figure 2 As shown, 6 foam pipes are provided. The mixing box 10 outputs 6 solution pipes; 6 air intake sections are provided, and the 6 air intake sections are all connected to the air intake section. The settings on each solution pipe are the same, and the settings on each air intake section are also the same.

[0097] Embodiment 9

[0098] Under current construction conditions, most shield tunneling drivers use semi-automatic foam injection mode instead of fully automatic foam injection mode because the foam nozzle of the foam system is easily clogged in fully automatic mode. However, in the semi-automatic foam injection mode, the amount of foam injected is large when the excavation speed is low, the state of the slag is difficult to control, and the cost is high.

[0099] The earth pressure balance shield foam system urgently needs to optimize the equipment, find a reasonable method for calculating the gas volume, and adopt a fully automatic foam injection mode to solve the problem of slag improvement in the foam system and reduce the cost of foam use.

[0100] The foam system generally has three injection modes: manual, semi-automatic and fully automatic. In the manual injection mode, the flow rate of the foaming agent mixture is controlled by adjusting the rotation speed of the second variable frequency screw pump 15, and the gas flow rate is controlled by adjusting the opening of the second electric switch 32; in the semi-automatic mode, the foam is automatically injected after inputting the parameters such as the flow rate, foaming rate, and foaming agent stock solution concentration of each foam tube; in the fully automatic mode, the foam is automatically injected after inputting the parameters such as the foaming rate, foaming agent stock solution concentration, the ratio of the foam generated by each foam tube to the total foam, and the injection rate in combination with the shield tunneling speed.

[0101] Calculation method of earth pressure balance shield foam system, including calculation methods of semi-automatic and fully automatic injection modes;

[0102] In semi-automatic mode:

[0103] In order to accurately calculate the gas volume, a gas pressure sensor 36 is set between the gas flow sensor 31 on the second intake section and the second electric switch 32 to measure the gas pressure value there; the gas pressure of the gas pressure sensor 36 is set to P Gas ;

[0104] Assume the soil tank pressure is P e , the foaming rate of each foam tube is x, and the foaming agent mixture of each foam tube is Q Liquid , the gas volume of each foam tube is Q Gas , the amount of foam generated by each foam tube is Q;

[0105] Calculation method of foaming agent mixture: Q Liquid =Q / x

[0106] There are two methods for calculating the amount of foam gas today:

[0107] ①Q Gas =Q×(1-1 / x)

[0108] ②Q Gas =Q×(1+P e )×(1-1 / x)

[0109] ① The gas volume calculation method is to treat the gas pressure of the foam generation equal to the soil chamber pressure, and ② the gas volume calculation method is to regard the gas generating foam as gas under standard atmospheric pressure. However, since the pressure of the foam generation gas is neither equal to the soil chamber pressure nor the standard atmospheric pressure, there is a deviation between the two gas volume calculation methods.

[0110] The present invention can accurately deduce the amount of gas required for foaming through the relationship between gas pressure and volume:

[0111] Semi-automatic mode: Q Gas =Q×(1-1 / x)×P e / P Gas

[0112] In full automatic mode:

[0113] Assume that the shield excavation face area is A, the excavation speed is v, the foam injection rate is y, and the total foam volume generated by the foam tube is Q 总 ;

[0114] Calculate the total foam volume Q required by the shield tunneling speed 总 =A×v×y, then calculate the amount of foam required for each foam pipe according to the proportion of foam in each foam pipe, and finally calculate the amount of foam required for each foam pipe according to Q Liquid =Q / x to calculate the amount of foaming agent mixed liquid for each foam tube, and according to Q Gas =Q×(1-1 / x)×P e / P Gas The gas volume is calculated by controlling the speed of the second variable frequency screw pump 15 to meet the foaming agent mixed liquid volume, and after accurately calculating the required gas volume, the opening of the second electric switch 32 is controlled to achieve the purpose of the required gas volume.

[0115] The present invention is provided with a solution generating unit and a gas transmission unit, and the solution and the gas are combined in the foam generator 21 and generate foam in the foam generator 21. A gas pressure sensor 36 is provided between the gas flow sensor 31 and the second electric switch 32 to accurately calculate the required gas amount, thus solving the problem of inaccurate calculation method of gas amount in the foam system.

[0116] Embodiment 10

[0117] During shield tunneling, the minimum foam injection volume parameter for each foam pipe is increased, and the sequence of shield cutter rotation and foam opening is optimized to avoid blockage of the foam pipe nozzle.

[0118] The main reason why the foam system's fully automatic injection mode is prone to clogging the foam pipe is that the foam injection volume is adjusted with the shield tunneling speed. When the shield just starts to tunnel or the tunneling speed is low, basically no foam is generated, which easily causes the foam nozzle to be blocked. Therefore, after repeated tests, the minimum foam injection volume is set to limit it (such as the minimum foam injection volume of each foam pipe is 20L / min), and the fully automatic foam injection must be started first, and the cutterhead rotation is started after the foam injection is normal. When shutting down, stop the cutterhead first and then turn off the foam, which can effectively avoid the blockage of the foam pipe nozzle. In the shield's fully automatic injection mode, each foam pipeline is set with a minimum foam flow limit, which can effectively reduce the probability of foam pipe blockage.

[0119] As the shield tunneling speed increases, when the optimized foam system fully automatic injection mode allocates the foam injection volume to each foam pipeline greater than the minimum foam injection (such as 20L / min-30L / min), full automatic control can be performed to improve the slag improvement effect and reduce the cost of foam use. In the shield fully automatic injection mode, each foam pipeline is set with a minimum foam flow limit, which can effectively reduce the probability of foam pipe blockage and reduce construction costs.

[0120] The above description is only to illustrate some principles and functions of the earth pressure balance shield foam system, working method and calculation method of the present invention, and is not intended to limit the present invention to the specific structure and applicable scope shown and described. Therefore, all corresponding modifications and equivalents that may be used belong to the scope of the patent applied for by the present invention.

[0121] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Calculation method of earth pressure balance shield foam system, characterized in that: include: The foam system includes semi-automatic and fully automatic injection mode calculation methods; In semi-automatic mode: A gas pressure sensor is set between the gas flow sensor on the second intake section and the second electric switch to measure the gas pressure value here; the gas pressure of the gas pressure sensor is set to P Gas ; Assume the soil tank pressure is P e , the foaming rate is x, and the foaming agent mixture is Q Liquid , the amount of gas is Q Gas , the amount of foam generated is Q; the amount of foaming agent mixed liquid is calculated as: Q Liquid =Q / x The amount of gas required for foam can be accurately derived from the relationship between gas pressure and volume: Semi-automatic mode: Q Gas =Q×(1-1 / x)×P e / P Gas In full automatic mode: Assume the shield excavation face area is A, the excavation speed is v, the foam injection rate is y, and the total amount of foam required is Q 总 ; Calculate the total foam volume Q required by the shield tunneling speed 总 =A×v×y, then calculate the amount of foam required for each foam pipe according to the proportion of foam in each foam pipe, and finally calculate the amount of foam required for each foam pipe according to Q Liquid =Q / x to calculate the amount of foaming agent mixture, and according to Q Gas =Q×(1-1 / x)×P e / P Gas Calculate the amount of gas.

2. Earth pressure balance shield foam system, characterized by: The calculation method of the earth pressure balance shield foam system according to claim 1 is applied, comprising a solution generating unit and a gas transmission unit, wherein the output pipes of the solution generating unit and the gas transmission unit are both connected to a foam generator, and the foam generator generates foam required for improving the earth pressure balance shield slag; The foam generator is connected to the foam pipe, and the foam in the foam pipe must be able to be sprayed in front of the cutter disc; The solution generating unit comprises a container for containing a foaming agent raw liquid, a raw liquid pipeline and a water inlet pipeline, wherein the raw liquid pipeline is connected to the container, and the end of the water inlet pipeline is a water inlet; the raw liquid pipeline and the water inlet pipeline are respectively connected to a mixing box or the raw liquid pipeline and the water inlet pipeline are connected to a tee, and a confluence pipeline is arranged between the tee and the mixing box; a solution pipeline is arranged between the mixing box and the foam generator; The gas transmission unit includes an air intake pipe, a condenser, a pressure reducing valve, a barometer, a gas pressure sensor and an electric switch; the air intake pipe includes an air intake section 1 and an air intake section 2, and the barometer includes a first barometer and a second barometer; the air intake section 1 is provided with a condenser, a pressure reducing valve and a first barometer in sequence along the air intake direction, and the air intake section 2 is provided with a gas pressure sensor, an electric switch and a second barometer in sequence along the air intake direction; the air intake section 2 is connected to a foam generator.

3. The earth pressure balance shield foam system according to claim 2, characterized in that: The container for holding the foaming agent raw liquid is a storage tank, and the bottom of the storage tank is connected to the raw liquid pipeline.

4. The earth pressure balance shield foam system according to claim 2, characterized in that: The raw liquid pipeline includes four sections, which are the first raw liquid pipe section, the second raw liquid pipe section, the third raw liquid pipe section and the fourth raw liquid pipe section; the second raw liquid pipe section and the third raw liquid pipe section are arranged between the first raw liquid pipe section and the fourth raw liquid pipe section, and the second raw liquid pipe section and the third raw liquid pipe section are arranged in parallel.

5. The earth pressure balance shield foam system according to claim 4, characterized in that: The second raw liquid pipe section is set as an overflow section, and the first safety overflow valve is installed on the second raw liquid pipe section; the first variable frequency screw pump is installed on the third raw liquid pipe section; the first liquid level sensor is also installed on the third raw liquid pipe section; the first liquid flow sensor is arranged on the third raw liquid pipe section, and the first liquid level sensor, the first variable frequency screw pump and the first liquid flow sensor are arranged in sequence in the flow direction of the raw liquid.

6. The earth pressure balance shield foam system according to claim 2, characterized in that: The second liquid level sensor, the third liquid level sensor and the fourth liquid level sensor are installed on the mixing box.

7. The earth pressure balance shield foam system according to claim 2, characterized in that: A second variable frequency screw pump and a third liquid flow sensor are arranged on the solution pipeline; second overflow sections are connected in parallel on both sides of the second variable frequency screw pump, and a second safety overflow valve is arranged on the second overflow section.

8. The working method of the earth pressure balance shield foam system is characterized by: The earth pressure balance shield foam system is the earth pressure balance shield foam system as claimed in claim 2; The steps include: After the first variable frequency screw pump is started, the foam agent liquid in the storage tank enters the inlet of the first variable frequency screw pump, and the high-pressure liquid is pumped out from the outlet of the first variable frequency screw pump, mixed with the water from the high-pressure water inlet through the first electric switch through the first one-way valve, and enters the mixing box; the order of generating foam is as follows: the foam agent mixed liquid in the mixing box enters the foam generator through the second stop valve, the second variable frequency screw pump, the second one-way valve, and the third stop valve; the high-pressure gas enters the foam generator through the air inlet, the fifth stop valve, the condenser, the pressure reducer, the second electric switch, the fourth one-way valve, and the sixth stop valve; the high-pressure foam agent mixed liquid and the high-pressure gas generate foam in the foam generator, and after passing through the foam inspection window and the third one-way valve, the slag in front of the cutter disc is improved.

9. The working method of the earth pressure balance shield foam system according to claim 8, characterized in that: include: (1) When there is no foaming agent liquid in the storage tank, the first liquid level sensor displays empty, and the first variable frequency screw pump is not allowed to start; (2) When the outlet pressure of the first variable frequency screw pump exceeds the safety pressure of the pump, the first safety relief valve opens and overflows back to the storage tank; (3) When the first variable frequency screw pump is started, the required water flow rate can be calculated according to the flow rate of the first liquid flow sensor and the foaming agent concentration value, and the opening of the first electric switch is adjusted according to the value of the second liquid flow sensor to achieve the required water flow value; (4) Three liquid level sensors are arranged in the mixing box: the second liquid level sensor, the third liquid level sensor and the fourth liquid level sensor; when the second liquid level sensor is powered on, it indicates that the liquid in the mixing box is full and the first variable frequency screw pump is shut down; when the third liquid level sensor loses power, it indicates that the liquid in the mixing box is almost used up and the first variable frequency screw pump is started; when the fourth liquid level sensor loses power, it indicates that the liquid in the mixing box is used up and the second variable frequency screw pump arranged on the solution pipeline is shut down and is not allowed to start; (5) When the outlet liquid pressure of the second variable frequency screw pump exceeds the safety pressure of the pump, the second safety relief valve opens to overflow; (6) The speed of the second variable frequency screw pump can be adjusted in real time according to the flow value of the third liquid flow sensor to achieve the desired liquid flow; (7) The opening of the second electric switch can be adjusted in real time according to the flow value of the gas flow sensor to achieve the desired gas flow; (8) The pressure value of the foam pressure sensor can be used to determine whether the foam pipeline is blocked.

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