Method for determining pressure balance when replacing screw machine with earth pressure balance shield machine

Abstract

The present invention relates to the technical field of shield machines, and in particular to a method for determining the pressure balance of an earth pressure balance shield machine when replacing a screw machine under pressure; the method comprises: a soil bin airtightness construction stage; a screw machine replacement stage; and a recovery excavation stage. The method for determining the pressure balance of an earth pressure balance shield machine when replacing a screw machine under pressure according to the present invention divides the entire process of replacing a screw machine under pressure into three stages: a soil bin airtightness construction stage, a screw machine replacement stage, and a recovery excavation stage. By comprehensively considering the pressure balance in the three stages, the safety of the earth pressure balance shield machine during the entire construction process of replacing a screw machine under pressure can be more accurately guaranteed, thereby avoiding problems such as ground subsidence, collapse, uplift, and cracking.

Description

Technical Field

[0001] The invention relates to the technical field of shield machines, and in particular to a method for determining pressure balance when a screw machine of an earth pressure balance shield machine is replaced under pressure. Background Art

[0002] When the earth pressure balance shield machine (EPB) passes through unevenly hard and soft strata with boulders, it is very easy to cause wear of the screw conveyor (screw machine for short) inside the earth pressure balance shield machine, and even cause the screw shaft to break. For example, the screw machine was stuck due to boulders in the 1112-1118 ring of the right line from Baimang Station to the middle ventilation shaft of Shenzhen Metro Line 13, and a large number of boulders were found on the face in the 1116 ring. The screw machine blades were severely worn, and many boulders were stuck in the screw machine, causing the screw machine shaft to break. Therefore, the screw machine needs to be replaced in the tunnel. The process of replacing the screw machine usually requires depressurizing the soil bin (to normal pressure) before replacing the screw machine. However, replacing the screw conveyor under normal pressure (without pressure) is only suitable for formations with good surrounding rock stability. In formations with weak surrounding rock stability, replacing the screw conveyor under normal pressure can easily cause instability of the face soil, thereby causing landslides and endangering the safety of construction workers. Replacing the screw conveyor under pressure can maintain the stability of the face and balance the pressure from the rock and soil above. Therefore, it is crucial to determine the pressure in the soil bin during the process of replacing the screw conveyor under pressure. If the pressure in the soil bin is too high, it will cause physical discomfort to the construction workers on the one hand, and it will cause bulges on the surface in front of the face on the other hand. If the pressure in the soil bin is too low, the pressure-maintaining effect cannot be fully reflected, and there is still a risk of instability of the face soil. Therefore, the starting point of this patent is to evaluate whether the pressure is balanced when the earth pressure balance shield machine (EPB) replaces the screw conveyor under pressure, so as to solve the pressure balance problem during the on-site replacement of the screw conveyor under pressure.

[0003] Therefore, a method for determining the pressure balance of an earth pressure balance shield machine when replacing the screw machine under pressure is proposed. Summary of the invention

[0004] The purpose of the present invention is to provide a method for determining the pressure balance of an earth pressure balance shield machine when replacing a screw machine under pressure, so as to solve the problems raised in the above technology.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] The method for determining the pressure balance of an earth pressure balance shield machine when replacing a screw machine under pressure includes:

[0007] Step 1: During the soil bunker airtightness construction phase, based on the geological exploration report, a geological model diagram is established when the earth pressure balance shield machine is replaced with a screw machine under pressure, the lower limit range A and the upper limit range B of the water and soil pressure distribution on the tunnel face are determined, and the pressure values ​​in different soil bunkers are determined in combination with the diameter of the shield machine;

[0008] Step 2: During the screw machine replacement phase, a pressure gauge is installed on the soil bin partition, and an external spare air compressor is set up. Based on the combination of segmented control and overall control during the construction process, the pressure change warning value during disassembly and the pressure change warning value in the bin when installing the new screw machine are set, and the new screw machine is installed;

[0009] Step 3: Return to the excavation stage, debug the new screw machine, slowly reduce the soil bin pressure to the normal soil bin pressure during the excavation stage, and conduct a trial push of the shield machine to promptly determine whether there are any abnormalities in the movement and deformation of the soil in front of the heading face. If there are no abnormalities, continue the push work. If there are abnormalities, pressurize and unload the soil bin, and maintain the pressure balance during the push stage.

[0010] Specifically, in the step 1, before the step of determining the lower limit range of the water and soil pressure distribution at the tunnel face and the upper limit range value of the water and soil pressure distribution at the tunnel face, it also includes determining the parameters required for calculating the self-weight stress of each soil layer in the geological model diagram, and the parameters include the gravity γ of each soil layer, the depth h of each soil layer, the position of the groundwater level, the depth h from the groundwater to the upper edge of the shield shell of the earth pressure balance shield machine, and the depth h of the groundwater to the upper edge of the shield shell of the earth pressure balance shield machine. 顶 , Depth from groundwater to the lower edge of the shield shell of the earth pressure balance shield machine h 底 , the depth h of the upper edge of the shield shell of the shield machine in the stratum where the shield is located (i+1)顶 , the depth of the lower edge of the shield shell of the shield machine in the stratum where the shield is located h (i+1)底 and the friction angle of the stratum where the shield is located

[0011] Specifically, in step 1, the calculation formula for the lower limit range A of the water and soil pressure distribution on the tunnel face is as follows:

[0012]

[0013]

[0014] Where: 顶 and A1 represent the lower limit of the water and soil pressure on the top of the shield shell of the shield machine, σ 底 A2 and A2 represent the lower limit of the water and soil pressure on the tunnel face at the bottom of the shield shell of the shield machine. a Represents the Rankine active earth pressure coefficient of the soil layer where the shield machine is located, h i represents the depth of soil layer i, γ i Represents the weight of soil layer i, that is, the lower limit of water and soil pressure distribution at the tunnel face is A1≤A≤A2.

[0015] Specifically, in step 1, the calculation formula for the upper limit range value B of the water and soil pressure distribution on the tunnel face is as follows:

[0016]

[0017]

[0018] Where: 顶 and B1 represent the upper limit of the water and soil pressure on the top of the shield shell of the shield machine. 底 and B2 represent the upper limit of the water and soil pressure on the tunnel face at the bottom of the shield shell of the shield machine, k P The Rankine passive earth pressure coefficient of the soil layer where the shield machine is located is That is, the upper limit range of water and soil pressure distribution on the tunnel face is B1≤B≤B2.

[0019] Specifically, in step 1, the pressure values ​​in different soil bins are determined in combination with the diameter of the shield machine, including:

[0020] When the diameter of the shield machine d≤14m, the pressure value in the soil bin is selected as min[1.5A2,0.7B2] to ensure the safety of the subsequent construction process;

[0021] When the diameter of the shield machine d>14m, the pressure value in the soil bin is selected as min[Q1,Q2], where:

[0022] Specifically, in the step 2, based on the combination of segmented control and overall control of the construction process, the pressure change warning value during disassembly and the pressure change warning value in the bin during installation of the new screw machine are set respectively, and the installation of the new screw machine is completed, including:

[0023] When 1.5A2 or Q1 is used as the pressure value in the soil bin, when the screw machine is removed and the pressure change is 0.2A2, an external standby air compressor is used to pressurize the bin to 1.3A2; when the screw machine is installed and the pressure change is 0.3A2, an external standby air compressor is used to pressurize the bin to 1.3A2, and it is ensured that the pressure in the bin is greater than A2 after the new screw machine is installed;

[0024] When 0.7B2 or Q2 is used as the pressure value in the soil bin, when the pressure change of 0.2Mpa is caused by the removal of the screw machine, an external spare air compressor is used to pressurize the bin by 0.2Mpa; when the pressure change of 0.3Mpa is caused during the installation of the screw machine, an external spare air compressor is used to pressurize the bin to 0.3Mpa, and it is ensured that the pressure in the bin is greater than A2 after the new screw machine is installed.

[0025] The beneficial effects of the present invention are as follows: the method for determining the pressure balance of the earth pressure balance shield machine when replacing the screw machine under pressure involves dividing the entire process of replacing the screw machine under pressure into three stages: the soil bin airtightness construction stage, the screw machine replacement stage and the recovery excavation stage. By comprehensively considering the pressure balance in the three stages, the safety of the earth pressure balance shield machine during the entire construction process of replacing the screw machine under pressure can be more accurately guaranteed, thereby avoiding problems such as surface subsidence, collapse, uplift and cracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flow chart of a method for determining pressure balance when replacing a screw machine under pressure in an earth pressure balance shield machine according to an embodiment of the present invention;

[0027] Figure 2 This is a simplified diagram of the geological model when the screw machine of the earth pressure balance shield machine under pressure is replaced in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] The present invention aims at the technical problem that the screw machine in the earth pressure balance shield machine is very likely to cause wear and even breakage of the screw shaft when the earth pressure balance shield machine passes through unevenly hard and soft strata with isolated rocks. The present invention adopts a method for determining the pressure balance when the screw machine of the earth pressure balance shield machine is replaced under pressure, and evaluates whether the pressure is balanced when the screw conveyor of the earth pressure balance shield machine is replaced under pressure. The method is used to solve the pressure balance problem in the process of replacing the screw machine under pressure on site, and can more accurately ensure the safety of the earth pressure balance shield machine during the entire construction process of replacing the screw machine under pressure, thereby avoiding problems such as surface subsidence, collapse, uplift and cracking.

[0030] Reference Figure 1 The present invention provides a method for determining the pressure balance of an earth pressure balance shield machine when replacing a screw machine under pressure, comprising the following steps:

[0031] Step 1: The soil bin airtightness construction phase.

[0032] S101: First, according to the geological exploration report and other documents, establish a geological model diagram for replacing the screw machine with an earth pressure balance shield machine under pressure (refer to the attached Figure 2 ).

[0033] For specific markings, please refer to the attached Figure 2The main features of the geological model diagram are: indicating the depth h and gravity γ of each soil layer; indicating the specific location of the groundwater level, especially the depth h from the groundwater to the upper edge of the shield shell of the earth pressure balance shield machine. 顶 ; Depth from groundwater to the lower edge of the shield shell of the earth pressure balance shield machine h 底 ; The depth of the upper edge of the shield shell of the shield machine in the stratum where the shield is located h (i+1)顶 ; The depth of the lower edge of the shield shell of the shield machine in the stratum where the shield is located h (i+1)底 .

[0034] S102: Determine the parameters required for calculating the self-weight stress of each soil layer in the geological model diagram. The specific parameters include the gravity γ of each soil layer, the depth h of each soil layer, the position of the groundwater level, and the depth h from the groundwater to the upper edge of the shield shell of the earth pressure balance shield machine. 顶 , Depth from groundwater to the lower edge of the shield shell of the earth pressure balance shield machine h 底 , the depth h of the upper edge of the shield shell of the shield machine in the stratum where the shield is located (i+1)顶 , the depth of the lower edge of the shield shell of the shield machine in the stratum where the shield is located h (i+1)底 and the friction angle of the stratum where the shield is located

[0035] S103: Determine the lower limit range A of the soil and water pressure distribution on the tunnel face.

[0036] The calculation formula for the lower limit range A of the water and soil pressure distribution on the tunnel face is as follows:

[0037]

[0038]

[0039] Where: 顶 and A1 represent the lower limit of the water and soil pressure on the top of the shield shell of the shield machine, σ 底 A2 and A2 represent the lower limit of the water and soil pressure on the tunnel face at the bottom of the shield shell of the shield machine. a Represents the Rankine active earth pressure coefficient of the soil layer where the shield machine is located, h i represents the depth of soil layer i, γ i Represents the weight of soil layer i, that is, the lower limit of water and soil pressure distribution at the tunnel face is A1≤A≤A2.

[0040] S104: Determine the upper limit range value B of the water and soil pressure distribution on the tunnel face.

[0041] The calculation formula for the upper limit range value B of the water and soil pressure distribution on the tunnel face is as follows:

[0042]

[0043]

[0044] Where: 顶 and B1 represent the upper limit of the water and soil pressure on the top of the shield shell of the shield machine. 底 and B2 represent the upper limit of the water and soil pressure on the tunnel face at the bottom of the shield shell of the shield machine, k P The Rankine passive earth pressure coefficient of the soil layer where the shield machine is located is That is, the upper limit range of water and soil pressure distribution on the tunnel face is B1≤B≤B2.

[0045] S105: Determine different soil bin pressure values ​​based on the diameter of the shield machine.

[0046] During the process of setting the pressure value in the soil bin, because the next construction step involves the replacement of the screw machine, and both the disassembly and installation of the screw machine require the bin door to be opened for construction, the air pressure in the original soil bin will drop. If the soil bin pressure is set according to the above calculated value, when the screw machine is replaced, the pressure in the soil bin will be lower than the water and soil pressure of the front face, thereby causing the front face to collapse.

[0047] Based on this, the shield machines are first classified according to their diameter. When the diameter of the shield machine is d≤14m, combined with relevant engineering experience, the pressure value in the soil bin is selected as min[1.5A2,0.7B2] to ensure safety in the subsequent construction process.

[0048] In addition, when the diameter of the shield machine d>14m, the pressure value in the soil bin is selected as min[Q1,Q2]. Because the pressure at the top and bottom of the shield shell of the shield machine is very different, using only the bottom pressure will make the pressure in the soil bin too high, which is not conducive to the construction workers' work. Therefore, the parameters are set:

[0049] Step 2: Screw machine replacement stage.

[0050] S201: Install a pressure gauge on the soil bin partition to monitor the pressure value change in the soil bin at all times.

[0051] In this embodiment, when the screw machine replacement construction begins, the shield body is in a power-off state and the soil bin pressure sensor cannot display. It is necessary to install 6 pressure gauges on the soil bin partition in advance, respectively set in the upper, middle and lower parts of the soil bin for comparative monitoring.

[0052] S202: Set up an external backup air compressor.

[0053] In this embodiment, when the pressure changes too much, the bin is pressurized in time to ensure the stability of the soil at the tunnel face. Bentonite slurry can also be injected into the soil bin and the cutterhead can be rotated to allow it to slowly increase to the set value.

[0054] S203: Based on the combination of segmented control and overall control of the construction process, a warning value for pressure change during disassembly and a warning value for pressure change in the bin during installation of a new screw machine are set respectively, and the installation of the new screw machine is completed.

[0055] In this embodiment, when 1.5A2 or Q1 is used as the pressure value in the soil bin, when the screw machine is removed and the pressure change is 0.2A2, the external standby air compressor is immediately used to pressurize the bin to 1.3A2; when the screw machine is installed and the pressure change is 0.3A2, the external standby air compressor is immediately used to pressurize the bin to 1.3A2. Finally, it should be ensured that after the new screw machine is installed, the pressure in the bin must be greater than A2.

[0056] In this embodiment, when 0.7B2 or Q2 is used as the pressure value in the soil bin, when the pressure change of 0.2Mpa is caused during the removal of the screw machine, the external standby air compressor is immediately used to pressurize the bin to 0.2Mpa; when the pressure change of 0.3Mpa is caused during the installation of the screw machine, the external standby air compressor is immediately used to pressurize the bin to 0.3Mpa. Finally, it should be ensured that after the new screw machine is installed, the pressure in the bin must be greater than A2.

[0057] Step 3: Return to the excavation phase.

[0058] S301: Debugging new screw machine.

[0059] In this embodiment, the overall linkage debugging of the shield machine is carried out. After the debugging is completed, try to start the newly replaced screw conveyor, first set the low-speed forward screw speed 1-3rpm, observe the screw machine torque, and before the torque reaches the rated torque, turn off the forward rotation of the screw machine and switch to the reverse mode to observe the screw machine torque. If the conventional operation cannot be started, inject an appropriate amount of bentonite slurry or foam mixture through the reserved valve hole of the screw machine, and continue to try the above forward and reverse switching operation steps until the screw machine can operate normally.

[0060] S302: Slowly reduce the soil bin pressure to the soil bin pressure in the normal excavation stage.

[0061] In this embodiment, surface observation points are densely arranged in front of the shield machine face (different from the observation point arrangement during normal advancement), and the soil bin pressure in the second stage is slowly reduced to the soil bin pressure in the normal excavation stage (there are a lot of theoretical research and engineering experience for reference in determining the soil bin pressure during normal excavation, which is the prior art and will not be repeated here).

[0062] S303: The shield machine conducts trial push and re-push to promptly determine whether there are any abnormalities in the movement and deformation of the soil in front of the face. If there are no abnormalities, the push and re-push work will continue. If there are abnormalities, the soil bin will be pressurized and unloaded to maintain the pressure balance during the push and re-push stage.

[0063] In this embodiment, during the trial and repeated pushing project of the shield machine, the movement and deformation of the surface soil in front of the heading face are observed in time. If there is no abnormality, the repeated pushing work is continued; if there is abnormal uplift on the surface (that is, the uplift value exceeds the specified range of the specification), the pressure relief operation is carried out in the soil bin; if there is abnormal settlement on the surface (that is, the settlement value exceeds the specified range of the specification), the pressurization operation is carried out in the soil bin.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A method for determining the pressure balance of an earth pressure balance shield machine when replacing a screw machine under pressure, characterized in that: include: Step 1: During the soil bunker airtightness construction phase, based on the geological exploration report, a geological model diagram of the earth pressure balance shield machine when replacing the screw machine under pressure is established, and the parameters required for calculating the self-weight stress of each soil layer in the geological model diagram are determined. The parameters include the gravity γ of each soil layer, the depth h of each soil layer, the position of the groundwater level, and the depth h from the groundwater to the upper edge of the shield shell of the earth pressure balance shield machine. 顶 , Depth from groundwater to the lower edge of the shield shell of the earth pressure balance shield machine h 底 , the depth h of the upper edge of the shield shell of the shield machine in the stratum where the shield is located (i+1)顶 , the depth of the lower edge of the shield shell of the shield machine in the stratum where the shield is located h (i+1)底 and the friction angle of the stratum where the shield is located Determine the lower limit range A and the upper limit range B of the water and soil pressure distribution on the tunnel face, and determine the pressure values ​​in different soil bins in combination with the diameter of the shield machine. The calculation formula for the lower limit range A of the water and soil pressure distribution on the tunnel face is as follows: Where: 顶 and A1 represent the lower limit of the water and soil pressure on the top of the shield shell of the shield machine, σ 底 A2 and A2 represent the lower limit of the water and soil pressure on the tunnel face at the bottom of the shield shell of the shield machine. a Represents the Rankine active earth pressure coefficient of the soil layer where the shield machine is located, h i represents the depth of soil layer i, γ i Represents the weight of soil layer i, that is, the lower limit of soil and water pressure distribution at the tunnel face is A1≤A≤A2; The calculation formula for the upper limit range value B of the water and soil pressure distribution on the tunnel face is as follows: Where: 顶 and B1 represent the upper limit of the water and soil pressure on the top of the shield shell of the shield machine. 底 and B2 represent the upper limit of the water and soil pressure on the tunnel face at the bottom of the shield shell of the shield machine, k P The Rankine passive earth pressure coefficient of the soil layer where the shield machine is located is That is, the upper limit range of the water and soil pressure distribution on the tunnel face is B1≤B≤B2; Step 2: During the screw machine replacement phase, a pressure gauge is installed on the soil bin partition, and an external spare air compressor is set up. Based on the combination of segmented control and overall control during the construction process, the pressure change warning value during disassembly and the pressure change warning value in the bin when installing the new screw machine are set, and the new screw machine is installed; Step 3: Return to the excavation stage, debug the new screw machine, slowly reduce the soil bin pressure to the normal soil bin pressure during the excavation stage, and conduct a trial push of the shield machine to promptly determine whether there are any abnormalities in the movement and deformation of the soil in front of the heading face. If there are no abnormalities, continue the push work. If there are abnormalities, pressurize and unload the soil bin, and maintain the pressure balance during the push stage.

2. The method for determining pressure balance when replacing a screw machine with pressure balance shield machine according to claim 1, characterized in that: In the step 1, the pressure values ​​in different soil bins are determined in combination with the diameter of the shield machine, including: When the diameter of the shield machine d≤14m, the pressure value in the soil bin is selected as min[1.5A2, 0.7B2] to ensure the safety of the subsequent construction process; When the diameter of the shield machine d>14m, the pressure value in the soil bin is selected as min[Q1, Q2], where 3. The method for determining pressure balance when replacing a screw machine with pressure balance shield machine according to claim 2, characterized in that: In the step 2, based on the combination of segmented control and overall control of the construction process, the pressure change warning value during disassembly and the pressure change warning value in the bin during installation of the new screw machine are set respectively, and the installation of the new screw machine is completed, including: When 1.5A2 or Q1 is used as the pressure value in the soil bin, when the screw machine is removed and the pressure change is 0.2A2, an external standby air compressor is used to pressurize the bin to 1.3A2; when the screw machine is installed and the pressure change is 0.3A2, an external standby air compressor is used to pressurize the bin to 1.3A2, and it is ensured that the pressure in the bin is greater than A2 after the new screw machine is installed; When 0.7B2 or Q2 is used as the pressure value in the soil bin, when the pressure change of 0.2Mpa is caused by the removal of the screw machine, an external spare air compressor is used to pressurize the bin by 0.2Mpa; when the pressure change of 0.3Mpa is caused during the installation of the screw machine, an external spare air compressor is used to pressurize the bin to 0.3Mpa, and it is ensured that the pressure in the bin is greater than A2 after the new screw machine is installed.

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