CN212272200U - Vertical shaft freezing system - Google Patents
Vertical shaft freezing system Download PDFInfo
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- CN212272200U CN212272200U CN202020442643.2U CN202020442643U CN212272200U CN 212272200 U CN212272200 U CN 212272200U CN 202020442643 U CN202020442643 U CN 202020442643U CN 212272200 U CN212272200 U CN 212272200U
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Abstract
The utility model discloses a shaft freezing system for in the perpendicular frozen subway shaft construction method, including the shaft, the periphery of shaft is encircleed and is provided with effective freezing layer, be provided with the outer pipe that freezes of well in the effective freezing layer, the outer pipe interval that freezes of well sets up, be provided with the interior pipe that freezes of well in the shaft, the pipe that freezes in the well encircles the shaft interval sets up, the bottom of shaft is provided with the shaft bottom plate, be provided with the buffer layer below the shaft bottom plate, the top of shaft is provided with fore shaft collar roof beam, the lower surface and the ground parallel and level of fore collar roof beam. The vertical shaft freezing system is rarely combined with a vertical shaft hanging upside down well wall method in the subway communication channel engineering, and the smooth implementation of the system provides a set of complete design and construction method for underground water treatment of the subway engineering, so that underground water resources are protected; meanwhile, the shaft freezing system is simple in structure and convenient to construct, and the construction rapidness is guaranteed.
Description
Technical Field
The utility model relates to a railway construction technical field, in particular to shaft freezing system.
Background
A certain underground excavated station of the Beijing subway is an underground three-layer three-span island type platform station, the effective platform width is 15m, the straight wall vault structure is covered with 11.86-12.56 m of soil, and the bottom plate burial depth is 34.81 m.
The station is constructed by adopting a subsurface excavation PBA construction method (4 pilot tunnels), and 3 construction vertical shafts are arranged in total. The vertical shaft is constructed by adopting an inverted well wall hanging method, the well depth is 37.881m, the thickness of a primary support is 350mm, and a support system is formed by sprayed concrete, a reinforcing mesh, a grid steel frame and a grouting anchor pipe.
The vertical shaft excavation depth range mainly comprises three layers of underground water, the front two layers of upper water retaining layers (I) and diving layers (II) are thin in vertical distribution range due to small water amount, deep hole grouting is adopted for water stopping, and the diving layer (III) starts from the position 9 meters away from the bottom of the vertical shaft and is mainly a pebble layer and pressure-bearing water. According to relevant regulations of Beijing city on strengthening underground water protection, the traditional direct precipitation method is cancelled, and a vertical freezing pipe is adopted to form a side wall and bottom waterproof curtain to achieve the waterproof effect.
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the technical problem that a shaft freezing system is provided, it has overcome prior art's above-mentioned defect.
The utility model discloses the technical problem that solve is realized through following technical scheme:
the vertical shaft freezing system is used in a vertical freezing subway vertical shaft construction method and comprises a vertical shaft, wherein an effective freezing layer is arranged around the periphery of the vertical shaft, an out-of-well freezing pipe is arranged in the effective freezing layer, the out-of-well freezing pipes are arranged at intervals, an in-well freezing pipe is arranged in the vertical shaft, the in-well freezing pipe surrounds the vertical shaft at intervals, a vertical shaft bottom plate is arranged at the bottom of the vertical shaft, a buffer layer is arranged below the vertical shaft bottom plate, a locking collar beam is arranged at the top end of the vertical shaft, and the lower surface of the locking collar beam is flush with the ground.
Preferably, in the above technical scheme, a temperature measuring hole and a well position observing hole are respectively arranged inside and outside the vertical shaft.
Preferably, in the above technical scheme, a water level observation hole is further arranged in the shaft.
Preferably, in the above technical solution, the width of the effective freezing layer is 2400mm, and the height thereof is 1400 mm.
Preferably, in the above technical solution, the distance from the effective freezing layer to the ground is 28880 mm.
The application utilizes the mode of artificial refrigeration, sends into the stratum with the low temperature refrigerant through salt solution circulation and freezes, along with single freezing wall diffusion and circle finally forms wholeness, high strength nature curtain, reaches stagnant water and pressure-bearing effect. Under the protection of a closed frozen earth wall, a special water stopping method for shaft excavation and primary support is carried out. Forming a special system.
The above technical scheme of the utility model, following beneficial effect has:
(1) by scientifically arranging freezing holes and freezing hole construction, installing a freezing station and strictly controlling active freezing and maintaining freezing, a waterproof curtain is formed to provide conditions for waterless safe operation of the vertical shaft, and the successful experience of the project is to provide more underground water solutions under the non-precipitation project policy.
(2) The combination of the freezing method and the vertical shaft inverted well wall method is rare, and the smooth implementation of the project provides a complete set of design and construction method for underground water treatment of subway projects. The construction method effectively protects underground water resources and has wide popularization and application prospects.
(3) The shaft freezing system has simple structure and simple and convenient construction, ensures the construction rapidity and simultaneously protects underground water resources.
Drawings
Fig. 1 is a sectional view of a shaft freezing system according to the present invention.
Fig. 2 is a plan view of the shaft freezing system of the present invention.
Detailed Description
The following detailed description of the present invention is provided to facilitate further understanding of the invention.
Example 1
A vertical shaft freezing system is used in a vertical freezing subway vertical shaft construction method and comprises a vertical shaft 1, wherein an effective freezing layer 2 is arranged around the periphery of the vertical shaft 1, an out-of-well freezing pipe 3 is arranged in the effective freezing layer 2, the out-of-well freezing pipes 3 are arranged at intervals, an in-well freezing pipe 4 is arranged in the vertical shaft 1, the in-well freezing pipes 4 are arranged at intervals around the vertical shaft 1, a vertical shaft bottom plate 5 is arranged at the bottom of the vertical shaft 1, a buffer layer 6 is arranged below the vertical shaft bottom plate 5, a locking collar beam 7 is arranged at the top end of the vertical shaft 1, and the lower surface of the locking collar beam 7.
The inside and the outside of the vertical shaft 1 are respectively provided with a temperature measuring hole 8 and a well position observing hole. A water level observation hole 9 is also arranged in the vertical shaft 1. Preferably, the effective freezing layer has a width of 2400mm, a height of 1400mm, and a distance of 28880mm from the ground. Of course, the present invention is not limited thereto, and those skilled in the art can select an appropriate size as needed.
The vertical shaft freezing system is applied to a vertical freezing subway vertical shaft construction method, and comprises the following specific steps:
(1) freezing hole construction
Construction equipment and configuration: and forming holes outside the vertical shaft by using a geological drilling machine, excavating to the top of a freezing range in the vertical shaft by using an MGL120 crawler-type anchoring drilling machine, and forming holes in a reverse circulation manner. One BW-200 type mud pump is selected as the mud pump, and the pump can be suitable for deep drilling with the depth of not more than 50-60 m.
The freezing hole construction process comprises the following steps:
(11) the freezing hole main process comprises the following steps: positioning and leveling; drilling; and (5) laterally inclining and correcting, discharging pipes and testing pressure.
(12) The construction requirements of the freezing hole are as follows: measuring the hole position inclination of each formed hole, controlling the inclination within 150mm, and measuring the frozen hole jelly
(13) After the freezing pipe is lowered into the stratum, pressure testing must be performed. The test pressure is 2 times of the salt water pressure of the freezing working surface, and is not lower than 0.8 MPa. The pressure drop should not exceed 0.05MPa after the pressure test for 30min, and the pressure is kept to be qualified after the pressure test for 15 min.
(2) Freezing refrigeration system installation
Freezing station arrangement: the equipment in the freezing station mainly comprises a power distribution cabinet, a freezing unit, a brine tank, a brine pump, a clear water tank, a cooling system, a clear water pump and the like. And arranging the freezing station on a ground freezing special platform according to the overall plan of the site construction. Preferably, the length of the stacking platform of the freezing station equipment is 20m, the width of the stacking platform is 6m, and the total floor area is 120m2。
Selecting the type of freezing equipment: two refrigerators (one for use and one for standby) are selected according to actual working conditions. JYSLG16F-M type refrigerating unit is adopted in the main operation, when the temperature of brine is-28 ℃ and the temperature of cooling water is 25 ℃ (lower), the rated refrigerating capacity of the unit is about 86000kcal/h, the rated power of a motor of the refrigerating unit is 125kw, and TBSJ050.1 type refrigerating unit is selected as a standby unit.
Pipeline connection and heat preservation: the saline water and the cooling water pipeline are connected by flanges and erected on the side wall of the occlusive pile by a pipe frame. The brine pipeline is installed off the ground to avoid water immersion and fluctuation. The return brine main pipe is bent in a reversed U shape. The saline pipeline is subjected to leakage testing and cleaning and then is insulated by polystyrene foam plastic, the thickness of the insulation layer is 50mm, and the outer surface of the insulation layer is wrapped by a plastic film. The high-pressure rubber tube is used for connecting the collecting and distributing liquid ring and the freezing tube. 3-7 freezing holes are connected in series, the series connection is carried out at intervals as much as possible, the total grouping is controlled within 15 groups, and the total length of each group of freezing holes is preferably similar. The evaporator and low-temperature pipeline of the refrigerating unit are made of soft foam plastic for heat preservation. The surface of the brine tank, the brine main pipe and the freezing plate is insulated by polystyrene foam plates.
Dissolving calcium chloride and filling fluorine into a machine set for oiling: firstly, the fresh water of about 1/4 is injected into the brine tank, then the pump is started to circulate and solid calcium chloride is added step by step until the brine concentration reaches the design requirement. Impurities are removed when dissolving calcium chloride. The brine tank cannot be filled too full to prevent the brine from overflowing when the brine flows back through the freezing pipe above the opening of the brine tank. The filling of the unit with fluorine and the filling of the refrigerator are carried out according to the requirements of the operating instruction of the equipment. Firstly, leak detection and nitrogen flushing of a refrigerating system are carried out, and after the system is ensured to be free of leakage, fluorine is refilled and oil is added.
(3) Active freeze and maintenance freeze
And debugging and commissioning are carried out after the equipment is installed. The refrigerator is started after checking and confirming that the operating parameters of the circuit system, the cooling water circulating system and the brine circulating system are normal. The refrigerator idles for 1-3 h, and whether the operation is abnormal is observed. During test operation, each state parameter such as energy, pressure, temperature and motor load is adjusted step by step, so that the unit operates under the technical parameter condition related to equipment regulations and operation requirements.
Actively freezing for 7 days until the temperature of the saline is reduced to minus 18 ℃ to minus 20 ℃; actively freezing for 15 days until the temperature of the saline is reduced to below-24 ℃; during excavation, the average temperature in the connection range of frozen soil and the pipe piece is lower than-5 ℃, the temperature of brine is reduced to be lower than-28 ℃, and the temperature difference of brine in a removing loop is not more than 2 ℃. If the brine temperature or the brine flow rate does not meet the design requirements, whether the active freezing time is prolonged or not is determined according to the freezing effect.
After the freezing is started, the freezing device is subjected to a itinerant check to see whether the brine leakage condition is caused by breakage, and once the brine leakage condition is found, the valve is closed immediately, and remedial measures are taken according to the brine leakage condition.
In the freezing process, the brine temperature of the main pipe and the main pipe of the return circuit, the temperature of a temperature measuring hole, the liquid level change of a brine tank and the temperature of cooling water are monitored every day, and whether the frost on the head part of the freezer melts abnormally or not is observed. And (3) detecting the brine flow of each freezer at the initial stage of freezing operation, and if the detected brine flow is less than the design requirement, adjusting by using a control valve or increasing the pump capacity of a brine pump to ensure that the brine flow meets the design requirement.
The freezing condition must be observed every day, the temperature of the temperature measuring hole is detected every day, the expansion speed and the thickness of the frozen wall are analyzed according to temperature measuring data, and the time for the frozen wall to reach the designed thickness is predicted.
(4) Freeze monitoring
The frozen water-stopping effect directly influences the excavation of the vertical shaft, and certain freezing risk exists. In the engineering, 4 temperature measuring holes are respectively arranged inside and outside the vertical shaft, and 3 well position observation holes are arranged in the vertical shaft.
Monitoring the soil temperature by using an implementation monitoring system in the freezing construction process of the vertical shaft; monitoring the working state of the freezing period through the temperature difference and the flow of the branch brine to the loop; a steel string type sensor is fixed on a temperature measuring pipe in a freezing wall to monitor frost heaving pressure.
(5) Excavation condition determination
(51) The active freezing time reached the design value of 40 days and the brine temperature was required to reach the design minimum brine temperature of-28 ℃.
(52) According to temperature measurement data of the temperature measurement holes, the average temperature and thickness of the frozen soil wall reach design required values, and an analysis report is written.
(53) And (5) detecting the detection holes, wherein the detection hole positions are selected at the positions with larger distances among the freezing holes or at the positions with abnormal freezing.
(6) Freezing pipe treatment in shaft excavation process
Because the frozen soil has high strength and good toughness, the ordinary hand pickaxe cannot be constructed, and an air pick is required to be adopted for tunneling. And in the tunneling construction, the excavation mode is adjusted in time according to the reinforcement effect of the exposed soil body and the construction monitoring information.
And (3) laying the earthwork in the prefabricated soil hopper while excavating, and hoisting along with excavation, wherein the freezing pipes are protected in the excavation process, and the next freezing pipe can be cut off and recovered when one freezing pipe is recovered.
(7) Thawing and precipitating grouting treatment
The engineering adopts natural thawing, and after freezing is stopped, the unused orifice pipe and freezing pipe on the wall are cut off immediately. The depth of cutting the orifice tube or freezing the tube requires that the depth of penetration into the wall should be no less than 60 mm.
Stopping freezing, unfreezing and sealing the freezing hole, then lining, filling and grouting, wherein the filling and grouting adopts the following steps of: 0.8-1 cement paste. The grouting pressure must not be greater than the hydrostatic pressure at the passage location. And grouting is performed from bottom to top, and the next layer of grouting can be stopped after the grouting holes in the previous layer continuously return.
And (4) after filling and grouting, if the stratum settlement is more than 0.5mm/d or the accumulated settlement is more than 3.0mm, performing thaw settlement compensation grouting, and suspending grouting when the stratum uplift reaches 3 mm. The melting and settling compensation grouting adopts cement-water glass double-liquid cement slurry as a main material, single-liquid cement slurry as an auxiliary material, a small amount of grouting pressure is not more than 0.5Mpa, and the grouting range is the whole freezing area on the principle of multiple times and uniformity.
And (3) completely melting the frozen wall, actually measuring the stratum sedimentation for one month and half a month, wherein the thickness of the stratum sedimentation is not more than 0.5mm, and basically keeping the ground deformation stable, namely stopping the thaw settlement compensation grouting.
The vertical shaft freezing system is rarely combined with a vertical shaft hanging upside down shaft wall method in the subway communication channel engineering. The smooth implementation of the project provides a set of complete design and construction method for underground water treatment of subway projects. The construction method effectively protects underground water resources and has wide popularization and application prospects.
Although the present invention has been described with reference to the above embodiments, it is not intended to limit the present invention, and various alternatives and modifications can be made by those skilled in the art without departing from the spirit and scope of the present invention.
Claims (5)
1. The utility model provides a shaft system of freezing, its characterized in that, includes shaft (1), the periphery of shaft (1) is provided with effective frozen layer (2) around, be provided with outer freezing pipe (3) of well in effective frozen layer (2), outer freezing pipe (3) interval sets up of well, be provided with in the shaft (1) and freeze pipe (4), it encircles to freeze pipe (4) in the well shaft (1) interval sets up, the bottom of shaft (1) is provided with shaft bottom plate (5), be provided with buffer layer (6) below shaft bottom plate (5), the top of shaft (1) is provided with fore shaft collar tie beam (7), the lower surface and the ground parallel and level of fore shaft collar tie beam (7).
2. Shaft freezing system according to claim 1, characterised in that the shaft (1) is provided with temperature measuring holes (8) and well position observation holes inside and outside, respectively.
3. A shaft freezing system as claimed in claim 1 wherein a water level sight hole (9) is provided in the shaft.
4. A shaft freezing system according to claim 1, wherein the effective frozen layer (2) has a width of 2400mm and a height of 1400 mm.
5. Shaft freezing system according to claim 1, characterised in that the effective frozen layer (2) is 28880mm from the ground.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020442643.2U CN212272200U (en) | 2020-03-31 | 2020-03-31 | Vertical shaft freezing system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020442643.2U CN212272200U (en) | 2020-03-31 | 2020-03-31 | Vertical shaft freezing system |
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| CN212272200U true CN212272200U (en) | 2021-01-01 |
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| CN202020442643.2U Active CN212272200U (en) | 2020-03-31 | 2020-03-31 | Vertical shaft freezing system |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112962624A (en) * | 2021-03-19 | 2021-06-15 | 中煤第五建设有限公司 | Double-curtain freezing groove wall method for ultra-deep and ultra-large complex foundation pit construction |
| CN113586061A (en) * | 2021-09-03 | 2021-11-02 | 中交二公局东萌工程有限公司 | Anti-frost-heaving system of vertical shaft in cold region and construction method thereof |
-
2020
- 2020-03-31 CN CN202020442643.2U patent/CN212272200U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112962624A (en) * | 2021-03-19 | 2021-06-15 | 中煤第五建设有限公司 | Double-curtain freezing groove wall method for ultra-deep and ultra-large complex foundation pit construction |
| CN112962624B (en) * | 2021-03-19 | 2022-05-10 | 中煤第五建设有限公司 | Double-curtain freezing groove wall method for ultra-deep and ultra-large complex foundation pit construction |
| CN113586061A (en) * | 2021-09-03 | 2021-11-02 | 中交二公局东萌工程有限公司 | Anti-frost-heaving system of vertical shaft in cold region and construction method thereof |
| CN113586061B (en) * | 2021-09-03 | 2023-11-21 | 中交二公局东萌工程有限公司 | Anti-frost-heaving system of cold region vertical shaft and construction method thereof |
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