A method for disassembling frozen monitoring control before fault of a shield machine

Abstract

The present application relates to a kind of frozen monitoring control methods before shield machine fault front, according to the requirement of passage excavation construction, using salt water circulation freezing method, the freezing process is divided into active freezing, maintenance freezing and stop freezing three processes, these three processes correspond to shield front, shield front and shield front respectively before disassembly, before disassembly, wherein the first two processes are carried out temperature monitoring to salt water system and frozen curtain.In front of shield front disassembly, soil needs to be frozen first, after freezing, passage excavation is carried out, after passage excavation, support, thawing are carried out, then shield machine head is pushed forward, with the pushing of shield machine, segment is gradually installed, after the pushing of shield machine is completed, it is not necessary to freeze again, and the first two processes need to keep soil frozen, so temperature monitoring is carried out to salt water system and frozen curtain in the first two processes, to ensure the smooth progress of shield front disassembly.

Description

TECHNICAL FIELD

[0001] The present application belongs to a kind of soil body freezing monitoring control method, more particularly to a kind of method for disassembling freezing monitoring control before shield machine failure. BACKGROUND

[0002] Shield method is a kind of tunneling construction method different from open construction method, and it constructs (lays) supporting segment of tunnel while tunneling, and shield machine is a kind of tunnel boring machine using shield method.Shield machine is a kind of underground construction equipment, and there are different shield machines according to different soil, so the soil characteristics to be excavated have been considered in the design of shield machine, so that even if failure occurs, it can be removed at the rear of the shield machine head.

[0003] However, shield machine sometimes encounters unknown obstacles in front, so that shield machine cannot advance, at this time, it is not the failure of shield machine itself, but the failure of excavation, and shield machine needs to be taken out to remove obstacles, but the auxiliary structure of shield machine makes shield machine unable to take out the head from the tunnel in the backward way.

[0004] In view of the above situation, technicians propose a kind of front disassembly method of shield machine to take out the head, and the front disassembly method needs to establish a channel in front of the head of shield machine, and the channel is formed by freezing existing soil and excavating support, and freezing needs to be detected and controlled in order to ensure the safety of excavation. SUMMARY

[0005] The present application provides a kind of method for disassembling freezing monitoring control before shield machine failure, according to the channel excavation construction requirement, the freezing process is divided into three processes of active freezing, maintenance freezing and stopping freezing, and the three processes correspond to shield front disassembly before, shield front disassembly in the middle and shield front disassembly after respectively, so that the temperature of brine system and freezing curtain is monitored in the first two processes, so as to ensure the smooth progress of shield front disassembly.

[0006] The technical scheme of the present application is as follows: a method for disassembling and thawing before shield machine failure, according to the channel excavation construction requirements, a salt water circulation freezing method is adopted, the freezing process is divided into three processes, namely, active freezing, maintenance freezing and stopping freezing, the three processes correspond to the front disassembly before the shield, the middle disassembly before the shield and the rear disassembly before the shield respectively, in the first two processes, the salt water system and the frozen curtain are monitored in temperature, in the active freezing, the outer ring and the inner ring are synchronously frozen, the salt water system temperature is controlled to below-18 DEG C, when the channel is excavated, one frozen curtain temperature measuring point is arranged at each of the four corner points around the excavation face and the middle point of the excavation face, the temperature of the side of the frozen wall is below-3 DEG C, in the maintenance freezing, the outer ring is frozen, the inner ring is stopped freezing and thawing, in the maintenance freezing, the salt water system temperature of the outer ring freezing is controlled to below-18 DEG C, when the temperature of the interface between the shield body outer wall and the frozen soil rises to zero, the thawing can be stopped, during the thawing, the temperature of the channel inner wall is measured, the temperature measurement interval is 2 hours, in the range of-25 DEG C to-5 DEG C, the shield machine head is pushed forward once every 5 DEG C, in the range of-5 DEG C to 0 DEG C, the shield machine head is pushed forward once every 0.5 DEG C.

[0007] According to the channel excavation construction requirements, the freezing process is divided into three processes, namely, active freezing, maintenance freezing and stopping freezing, the three processes correspond to the front disassembly before the shield, the middle disassembly before the shield and the rear disassembly before the shield respectively, the soil needs to be frozen before the front disassembly before the shield, the channel is excavated after the soil is frozen, the support and thawing are carried out after the channel excavation, then the shield machine head is pushed forward, with the pushing forward of the shield machine, the segment is gradually installed, after the pushing forward of the shield machine is completed, the freezing is not needed, in the first two processes, the salt water system and the frozen curtain are monitored in temperature, so that the smooth progress of the front disassembly before the shield is ensured.

[0008] As preferred, the cooling water consumption is calculated before freezing, W=W1+N×W2, in the formula, N is the number of oil coolers, , in the formula, W1 is the total flow m 3 / h required for the condenser to circulate cooling water; Q T is the calculated refrigeration capacity kcal / h, γ is the density of water, and γ=1.0 t / m 3 , c is the heat capacity of water, and c=1000 kcal / t℃, and Δt is the circulating water temperature difference; the circulating amount of the cooling water of the oil cooler is calculated according to the following formula: , in the formula, W2 is the circulating amount m 3 / h of the cooling water required for the oil cooler, and Δt y is the temperature difference of the water in and out of the oil cooler in design, and Wy is the water consumption of each oil cooler in design, and the value is 8 m 3The soil body is frozen by salt water circulation, so the amount of cooling water needs to be considered. The cooling water tower and cooling unit of the freezing system are set by calculating the amount of cooling water, and the freezing cooling circulation condition is obtained according to the monitoring data of the cooling unit.

[0009] Preferably, the amount of salt water circulation is calculated before freezing, , wherein W is the amount of salt water circulation received by the shield m 3 , Qt is the cooling amount received by the shield kcal / h, γ is the density of salt water, and γ=1.26 t / m 3 , c is the heat capacity of salt water, c=653 kcal / t℃, and Δt is the temperature difference of the salt water in the circuit, Δt=1.6℃. The amount of salt water required for freezing is calculated by the amount of salt water circulation, and the salt water pump is set. The freezing condition of the freezing pipeline is obtained according to the monitoring of the amount of salt water circulation.

[0010] Preferably, Qt is set to 6.31×10 4 kcal / h according to the thickness and maintenance time of the frozen soil body. The cooling water pump and the salt water pump are selected according to the amount of cooling water and the amount of salt water circulation, and the specific gravity of the salt water is 1.260-1.265.

[0011] Preferably, the freezing pipes used in freezing are arranged in an inner ring and an outer ring. The freezing pipes in the inner ring are one-way, and the freezing pipes in the outer ring are one-way. The two-way freezing pipes are independent, and each way of the freezing pipes is connected to a freezing station. The difference between the first two freezing processes is whether the freezing pipes in the inner ring participate in freezing. In the active freezing process, all the freezing pipes are frozen. In the maintenance freezing process, the freezing pipes in the outer ring continue to actively freeze, and the freezing pipes in the inner ring stop freezing, so as to avoid freezing between the shield machine head and the passage wall during the advancing process of the shield machine head.

[0012] Preferably, temperature measuring holes are arranged outside the outer ring of the outer ring freezing pipes and inside the inner ring of the inner ring freezing pipes. The radial distance between the temperature measuring holes in the inner ring and the temperature measuring holes outside the outer ring is the radial thickness of the frozen soil body, and the position of the temperature measuring holes in the inner ring is just corresponding to the position of the four corner points of the passage.

[0013] The beneficial effects of the present application are: according to the requirements of the passage excavation construction, the freezing process is divided into three processes of active freezing, maintenance freezing and stop freezing, which correspond to the shield front disassembly before, during and after, respectively. The soil needs to be frozen before the shield front disassembly, the passage is excavated after the soil is frozen, the support and thawing are carried out after the passage is excavated, and then the shield machine head is pushed forward. With the pushing of the shield machine, the segment is gradually installed. After the pushing of the shield machine is completed, freezing is no longer needed. Therefore, the temperature of the salt water system and the freezing curtain is monitored in the first two processes, so as to ensure the smooth progress of the shield front disassembly. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a refrigerant tube arrangement according to the present invention;

[0015] In the diagram: 1. Channel, 2. Temperature measuring tube, 3. Inner ring freezing tube, 4. Outer ring freezing tube, 5. Frozen soil. Detailed Implementation

[0016] The present invention will be further described below through specific embodiments and in conjunction with the accompanying drawings.

[0017] Example:

[0018] like Figure 1 As shown, a structure for refrigeration pipes in a pre-fault removal channel of a tunnel boring machine (TBM) is presented. The refrigeration pipes are made of low-carbon seamless steel. Channel 1 is cylindrical, with two rings of refrigeration pipes arranged radially outward from the removal channel, forming a double-layer refrigeration structure of inner and outer rings. The length of the refrigeration pipes is greater than the distance between the front end of the TBM head and the surface of the diaphragm wall. Generally, the length of the removal channel is controlled at around 2 meters. The number of inner ring refrigeration pipes 3 is equal to the number of outer ring refrigeration pipes 4. The outer ring refrigeration pipes are arranged at equal intervals, while half of the inner ring refrigeration pipes are in the upper half and the other half are in the lower half. The inner ring refrigeration pipes in the lower half are arranged at equal intervals, while the inner ring refrigeration pipes in the upper half are concentrated on both sides. A total of 56 cryogenic tubes are used: 28 inner ring cryogenic tubes and 28 outer ring cryogenic tubes. 15 inner ring cryogenic tubes are located in the upper half of the ring, and 13 are located in the lower half. Three inner ring cryogenic tubes are concentrated on each side of the upper half, while the remaining nine are evenly distributed at the top. The cryogenic tubes are connected to the freezing station in groups, with each group's tubes connected in series. A horn-shaped tube is welded to each cryogenic tube, which is connected to a flexible hose covered with a rubber-plastic insulation layer. In this embodiment, four cryogenic tubes form a group, forming 14 groups connected to the freezing station. The four cryogenic tubes within the same group are connected in series. The freezing station uses brine freezing circulation and includes a refrigeration unit, cooling device, brine circulation pump, brine tank, and brine circulation pipes connected to the cryogenic tubes. Multiple temperature measuring tubes 2 are also installed inside the frozen soil body 5. The temperature measuring tubes are located on the outer periphery and the inner periphery of the frozen soil circle. There are 4 temperature measuring tubes on the outer periphery, which are located on the bisectors of the 4 quadrants respectively. There are 4 temperature measuring tubes on the inner periphery, which are located on the 4 axes respectively. The positions of the temperature measuring holes in the inner periphery correspond exactly to the positions of the 4 corner points of the channel.

[0019] A method for disassembling frozen monitoring control before shield machine failure, according to the channel excavation construction requirement, the salt water circulation freezing method is adopted, the freezing process is divided into three processes, namely active freezing, maintenance freezing and stopping freezing, the three processes correspond to the front disassembly before shield, the middle disassembly before shield and the rear disassembly before shield respectively, the salt water system and the frozen curtain are monitored in the first two processes, wherein the active freezing adopts the synchronous freezing mode of the outer ring and the inner ring, the salt water system temperature during the active freezing is controlled to below-18 DEG C, when the channel is excavated, one frozen curtain temperature measuring point is arranged at each of the four corner points of the excavation face and the midpoint of the excavation face, the temperature of the side of the frozen wall is below-3 DEG C, the maintenance freezing adopts the mode of outer ring freezing, inner ring stopping freezing and thawing, when the maintenance freezing, the salt water system temperature of the outer ring freezing is controlled to below-18 DEG C, the thawing can be stopped when the temperature of the interface between the shield body outer wall and the frozen soil rises to zero, the temperature of the inner wall of the channel is measured during the thawing, the temperature measuring interval is 2 hours, the shield machine head is pushed forward once every 5 DEG C in the range of-25 DEG C to-5 DEG C, the shield machine head is pushed forward once every 0.5 DEG C in the range of-5 DEG C to 0 DEG C. In addition to the temperature monitoring of the salt water system and the frozen curtain, the frozen device return circuit salt water temperature, the cooling circulating water inlet and outlet temperature, the salt water pump working pressure and the refrigeration system condensing pressure are also monitored.

[0020] The salt water system and the frozen curtain temperature monitoring are measured by using the temperature measuring instrument and combining the precise mercury thermometer, the monitoring frequency is 1-3 times per day, and the monitoring is once every 2 hours if necessary.

[0021] The pressure monitoring and the salt water liquid level monitoring are simultaneously performed during the temperature monitoring process, the working pressure of the refrigeration system and the salt water system is measured by installing the pressure gauge, the high pressure system of the refrigeration selects the 0-2.5 MPa pressure gauge, the medium and low system selects the 0-1.6 MPa pressure gauge, the monitoring frequency is once per shift. The salt water level alarm system and the liquid level scale are installed in the salt water tank, the salt water tank liquid surface has a decrease of 10 mm, the abnormality is found in time and reported and handled.

[0022] The cooling water consumption calculation is performed before freezing, W=W1+N×W2, wherein N is the number of oil coolers, , wherein W1 is the total flow rate m 3 / h required for the condenser to circulate cooling water; QT is the calculated refrigeration capacity kcal / h, gamma is the density of water, taken as gamma=1.0 t / m 3 , c is the water heat capacity, taken as c=1000 kcal / t DEG C, and delta t is the circulating water temperature difference; the oil cooler cooling water circulation amount is calculated according to the following formula: , wherein W2 is the oil cooler required cooling water circulation amount m 3 / h, delta t y is the design oil cooler inlet and outlet water temperature difference, and Wy is the water consumption of each oil cooler, taken as 8 m 3 / h. QT is set to 6.31 x 104kcal / h according to the thickness of frozen soil and the maintenance time. 4 kcal / h, m 3 / h, m 3 / h, W = 127.5 m 3 / h, two skd136 type refrigerators are selected for the freezing station, one of which is used as a backup, and two cooling towers are provided, each of which is equipped with a cooling water tank with a size of 12000 (length) x 6000 (width) x 1500 (height) and welded with a 5mm steel plate.

[0023] The salt water circulation quantity calculation is carried out before freezing, , wherein W is the salt water circulation quantity received by the shield m 3 / h, QT is the cooling quantity received by the shield 6.31 x 104kcal / h, γ is the density of salt water, and γ = 1.26 t / m 3 , c is the heat capacity of salt water, c = 653 kcal / t℃, and Δt is the temperature difference of the salt water in the circuit, Δt = 1.6℃. W = 92 m 3 / h, two salt water pumps are set for the freezing station, each with a flow of 200 m 3 / h (head 50 m), each with a power of 37 kw, one of which is used as a backup, and a salt water tank is set, the salt water tank has a size of 1500 (length) x 1500 (width) x 1600 (height) and is welded with a 4mm steel plate, the salt water tank steel plate is double-sided brushed with anti-rust paint, and the salt water specific gravity is 1.260-1.265.

[0024] The process of active freezing is as follows: (1) After confirming that the circuit system, the cooling water circulation system and the salt water circulation system are normal, the refrigerator is started. The refrigerator is first idled for 1-3h, and then liquid is supplied for refrigeration after observing that the idling is normal.

[0025] (2) The freezing system is tested. The energy, pressure, temperature and motor load and other state parameters are gradually adjusted so that the unit operates under the technical parameters of the relevant equipment regulations and operation requirements.

[0026] (3) After the test operation is normal, active freezing is carried out. The operating parameters of the refrigerator are adjusted according to the cooling water temperature and the salt water temperature to improve the refrigeration efficiency of the refrigerator.

[0027] (4) After the freezing is started, the frost on the freezer and the return water temperature are checked to ensure that the salt water flow of the freezer is uniform.

[0028] (5) After active freezing for one week, the salt water temperature is reduced to below -18℃, and the salt water temperature is reduced to the design minimum salt water temperature requirement during excavation.

[0029] (6) According to the temperature monitoring result of the temperature hole, the formation condition of the frozen wall is analyzed, including the freezing wall circle situation, average temperature and expansion thickness, etc.

[0030] (7) According to the frozen wall temperature monitoring, the development trend of the frozen wall is predicted.

[0031] (8) Every 2 hours, the frozen system operation parameters are checked and recorded to determine the normal freezing.

[0032] After the channel excavation is completed, the shield machine is pushed forward, and due to active freezing, the soil around the shield shell is frozen after excavation, which causes the shield machine to be unable to dig, so it is necessary to thaw the contact part between the outer wall of the shield shell and the soil, and then the shield machine is pushed forward after thawing, which is the maintenance freezing process. The inner circle freezing pipe stops freezing, the outer circle freezing pipe continues active freezing, and a steam generator is placed in the tunnel to blow steam to the shield body. In order to ensure the uniformity of thawing, the man door is opened and steam is blown at the cutout for thawing.

[0033] The frozen soil temperature is observed through the radial hole of the shield body, and when the temperature of the interface between the outer wall of the shield body and the frozen soil rises to zero, the thawing can be stopped. During the thawing, thermometers are attached to the inside of the shield shell to monitor and record the temperature, and the re-pushing is immediately carried out when the thawing requirements are met. During the thawing, the inner wall of the channel is temperature measured, the temperature measurement interval is 2 hours, and the shield machine head is pushed forward once every 5℃ in the range of-25℃~-5℃; the shield machine head is pushed forward once every 0.5℃ in the range of-5℃~0℃.

[0034] After the shield machine is pushed out of the channel opening, the inner wall of the channel has also been installed with segments, and then the freezing is stopped. During the stopping of the freezing process, the channel is subjected to thawing and sinking grouting, and the grouting range is the frozen soil thawing area. When the settlement is greater than 0.5mm or the cumulative settlement is greater than 1.0mm, tracking grouting should be carried out; when the subsurface tunnel uplift reaches 2.0mm, the grouting should be temporarily stopped. If the actual measured cumulative subsurface tunnel settlement is not greater than 0.5mm every 15 days within one month, the tracking grouting can be ended.

[0035] After the grouting is completed, the shield machine head is disassembled forward.

[0036] The above is only the preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent transformation of the above embodiment according to the technical essence of the present application still belongs to the protection scope of the technical solution of the present application.

Claims

1. A method for monitoring and controlling a frozen section before a fault of a shield tunneling machine, characterized in that, The shield machine is disassembled before the failure, and the machine head is taken out forwardly when the machine cannot retreat due to the failure of tunneling, and a channel is established in front of the machine head, according to the channel excavation construction requirements, the salt water circulation freezing method is used, the freezing process is divided into three processes, namely, active freezing, maintenance freezing and stopping freezing, the three processes correspond to the front, middle and rear of the shield disassembly, and the salt water system and the frozen curtain are monitored in the first two processes, wherein the active freezing adopts the synchronous freezing mode of the outer ring and the inner ring, the salt water system temperature is controlled below-18 DEG C during the active freezing, four corner points and the midpoint of the excavation face are arranged with a frozen curtain temperature measuring point during the channel excavation, the temperature of the side of the frozen wall is below-3 DEG C, the maintenance freezing adopts the mode of outer ring freezing, inner ring stopping freezing and thawing, the salt water system temperature of the outer ring freezing is controlled below-18 DEG C during the maintenance freezing, the thawing is stopped when the temperature of the interface between the outer wall of the shield body and the frozen soil rises to zero, the inner wall of the channel is temperature measured during the thawing, the temperature measurement interval is 2 hours, the machine head is pushed forward once every 5 DEG C in the range of-25 DEG C to-5 DEG C, and the machine head is pushed forward once every 0.5 DEG C in the range of-5 DEG C to 0 DEG C.

2. The method according to claim 1, characterized in that, Cooling water consumption calculation is carried out before freezing, W=W1+N×W2, wherein N is the number of oil coolers, W1 is the total flow m of condenser required cooling water circulation calculation 3 QT is the calculated refrigeration capacity kcal / h, γ is the density of water, taken γ=1.0 t / m 3 , c is the water heat capacity, taken c=1000 kcal / t℃, △t is the circulating water temperature difference; the oil cooler cooling water circulation is calculated according to the following formula: W2=W1×(1-γ×c×△t), wherein W2 is the circulating amount m of cooling water required by the oil cooler, △ty is the temperature difference of the designed oil cooler inlet and outlet water, Wy is the water consumption of each oil cooler, taken as 8 m 3 / h. 3 / h.

3. The method according to claim 2, wherein, The salt water circulation amount before freezing is calculated, W = (QT - Q) / (γ * c * △t) 3 wherein W is the salt water circulation amount received by the shield m / h, QT is the cooling amount received by the shield kcal / h, γ is the salt water density, taken as γ = 1.26 t / m 3 c is the salt water heat capacity, taken as c = 653 kcal / t℃, and △t is the temperature difference of the salt water in and out of the circuit, taken as △t = 1.6℃.

4. The method according to claim 2 or 3, characterized in that, QT is set to 6.31 x 10 4 kcal / h, and the cooling water pump and the brine pump are selected according to the amount of the cooling water and the amount of the brine circulation, and the specific gravity of the brine is 1.260 to 1.

265.

5. The method according to any one of claims 1-3, wherein the method further comprises: determining whether the fault has occurred; and if the fault has occurred, stopping the tunneling machine and initiating the thawing process. 5 The freezing pipes used for freezing are arranged into an inner ring and an outer ring, the freezing pipes of the inner ring are one-way, the freezing pipes of the outer ring are one-way, the two-way freezing pipes are independent, and each way of the freezing pipes is connected to a freezing station.

6. The method according to claim 5, wherein, The temperature measuring holes are arranged outside the outer ring of the outer ring freezing pipes and inside the inner ring of the inner ring freezing pipes, the radial distance between the temperature measuring holes in the inner ring and the temperature measuring holes outside the outer ring is the radial thickness of the frozen soil, and the positions of the temperature measuring holes in the inner ring are just corresponding to the positions of the four corner points of the channel.

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