CN116087259A - Pipe curtain freezing test device and test method for simulating underground water seepage - Google Patents
Pipe curtain freezing test device and test method for simulating underground water seepage Download PDFInfo
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- CN116087259A CN116087259A CN202211540927.5A CN202211540927A CN116087259A CN 116087259 A CN116087259 A CN 116087259A CN 202211540927 A CN202211540927 A CN 202211540927A CN 116087259 A CN116087259 A CN 116087259A
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Abstract
The invention discloses a pipe curtain freezing test device and a pipe curtain freezing test method for simulating underground water seepage, and belongs to the technical field of underground engineering construction freezing. The device comprises a test box, wherein soil layers simulating underground states are filled in the test box, a pipe curtain freezing system is arranged in the test box, the pipe curtain freezing system comprises a plurality of concrete jacking pipes, empty jacking pipes, round freezing pipes and special-shaped freezing pipes which are horizontally arranged in the soil layers and penetrate through the soil layers at the front end and the rear end, and a temperature detection system is arranged around the pipe curtain freezing system; the left and right sides of the test box are respectively provided with a constant temperature infiltration system for keeping the temperature of the soil layer, the pipe curtain freezing system is connected with a circulating cold source, and the outside of the test box and the outside of the constant temperature infiltration system are respectively wrapped with heat preservation materials so as to reduce the contact of external environment and ensure the overall temperature balance. The freezing pipe has a simple structure, is convenient to use, and can obtain the freezing effect of different freezing pipes in a seepage soil layer.
Description
Technical Field
The invention relates to a pipe curtain freezing test device and a test method for simulating underground water seepage, and belongs to the technical field of pipe curtain freezing when high seepage exists in a stratum in underground engineering construction.
Background
Because the freezing wall has higher mechanical strength and good water sealing performance, the underground engineering adopts an artificial stratum freezing method to strengthen soil or isolate underground water. According to the traditional freezing method, a freezing pipe is arranged around a soil body to be excavated, a low-temperature refrigerant is introduced into the freezing pipe to freeze the soil layer, and a closed freezing curtain is formed, so that a good excavation construction environment is created. However, when the ultra-shallow buried stratum and the ultra-large section freezing engineering are met, the design requirement cannot be met by singly depending on the freezing wall bearing. Meanwhile, for a curve freezing pipe, the traditional horizontal drilling process is difficult to ensure the hole forming precision of the freezing hole, so that water sealing failure is caused, and engineering disasters are caused.
The pipe curtain freezing engineering uses a pipe curtain freezing method as a core technology, combines the pipe curtain method and the freezing method, utilizes the inside of a pre-constructed pipe jacking to carry out freezing pipe arrangement, and is used as a novel tunnel shallow-buried underground excavation method, and the method is applied to the north arch tunnel of the bridge bead sea connecting line of the Gangzhu Australian bridge for the first time. The construction method has reliable bearing and water sealing performances, has the advantages of controllable and visible temperature, and is widely popularized in urban tunnel engineering construction. However, when the pipe curtain freezing method is applied to water flow environments such as crossing rivers and lakes, the groundwater flow speed is high, so that the weakening effect of a frozen soil temperature field is unavoidable, the groundwater leakage is caused, even the groundwater flows into the structure, and the construction safety is affected. Therefore, the method is necessary to study the evolution rule of the pipe curtain freezing temperature field of the high-seepage stratum under the flowing water condition by aiming at the pipe curtain freezing engineering and starting from a model test under the flowing water condition, and provides basis and reference for the pipe curtain freezing engineering design and optimization. At present, a reliable test device is not available for simulating a pipe curtain freezing method under the seepage condition, and the freezing effect of a pipe curtain freezing complex pipe distribution form under the influence of external factors such as different seepage speeds, water temperatures and the like cannot be accurately reflected.
Disclosure of Invention
Aiming at the defects of the prior art, the pipe curtain freezing test device and the pipe curtain freezing test method for simulating underground water seepage can be used for carrying out pipe curtain freezing seepage tests under the conditions of different seepage speeds and different underground water temperatures, verifying the safety and applicability of pipe curtain freezing various freezing pipe arrangement modes under the effect of weakening the underground water seepage, obtaining the freezing temperature of a stratum key position, evaluating the distribution state of a pipe curtain freezing temperature field under the seepage condition, and providing important references for the design and construction of the underground engineering for crossing the water-rich stratum by adopting a pipe curtain freezing method.
In order to achieve the technical aim, the pipe curtain freezing test device for simulating groundwater seepage comprises a test box, wherein soil layers simulating underground states are filled in the test box, each soil layer is composed of clay and sand, a pipe curtain freezing system is arranged in the test box and comprises a plurality of concrete jacking pipes, empty jacking pipes, round freezing pipes and special-shaped freezing pipes which are horizontally arranged in the soil layer and penetrate through the soil layers at the front end and the rear end, and a temperature detection system is arranged around the pipe curtain freezing system; the left and right sides of the test box are respectively provided with a constant temperature infiltration system for keeping the temperature of the soil layer, the pipe curtain freezing system is connected with a circulating cold source, and the outside of the test box and the outside of the constant temperature infiltration system are respectively wrapped with heat preservation materials so as to reduce the contact of external environment and ensure the overall temperature balance.
Further, the constant-temperature permeation system comprises an upstream cavity water storage tank and a downstream cavity water storage tank which are respectively and closely arranged on two sides of a soil layer of the test box, and a constant-temperature water tank and a constant-pressure water tank which are arranged at the horizontal height of the test box, wherein the upstream cavity water storage tank and the downstream cavity water storage tank are communicated with two sides of a simulated soil layer of the test box, constant-temperature water is injected into the constant-pressure water tank through a clear water circulating pump, water is injected into the upstream cavity water storage tank through a clear water supply pipe at the bottom of the constant-temperature water tank through gravity, and the constant-temperature water tank is connected with the constant-temperature water tank through a clear water return pipe; the constant-pressure water tank is provided with an overflow port connected with the constant-temperature water tank through an external overflow pipe, and water in the water storage tank of the upstream cavity moves to the water storage tank of the downstream cavity under the pressure action provided by the constant-pressure water tank to form seepage in a soil layer; the clear water supply pipe and the clear water return pipe are vertically arranged on the horizontal plane with the pipe curtain freezing system, so that constant-temperature water seepage in the soil layer tangentially moves the pipe curtain freezing system, and the heights of the outlets of the clear water supply pipe and the clear water return pipe are flush with the pipe curtain freezing system.
Further, temperature detecting system includes a plurality of temperature sensor and data acquisition ware, and all temperature sensor all lead to through data transmission lead wire connection data acquisition ware, wherein all is equipped with temperature sensor in all concrete push pipes, empty push pipes, circular freezing pipe and dysmorphism freezing pipe's pipeline top, all is equipped with temperature sensor between all adjacent concrete push pipes, empty push pipes, circular freezing pipe and dysmorphism freezing pipe for detect the soil body temperature of freezing the in-process at different moment.
Furthermore, as the horizontal drilling precision cannot ensure that the frozen pipe is directly driven into the soil layer without generating cheap positions, the frozen pipe is required to be arranged in a concrete jacking pipe or an empty jacking pipe; therefore, the pipe curtain freezing system is also characterized in that the freezing pipes are arranged in a plurality of concrete jacking pipes and empty jacking pipes which are alternately and horizontally arranged;
the plurality of round freezing pipes or special-shaped freezing pipes are axially fixed in the inner wall of the concrete jacking pipe or the hollow jacking pipe in a welding mode, the two ends of the round freezing pipes and the special-shaped freezing pipes are exposed out of 10cm of the two ends of the concrete jacking pipe or the hollow jacking pipe for installing connecting pipes, and the diameter and wall thickness parameters of the concrete jacking pipe, the hollow jacking pipe, the round freezing pipes and the special-shaped freezing pipes are determined according to a freezing scheme.
Furthermore, at least two circular freezing pipes are arranged in the concrete jacking pipe and are respectively arranged at two waists at the inner side of the concrete jacking pipe, and when the number of the circular freezing pipes exceeds two, the circular freezing pipes are arranged in an upper inner cavity of the concrete jacking pipe between the circular freezing pipes at the two waists at the inner side at equal intervals;
the special-shaped freezing pipes are arranged at least in the hollow jacking pipe, are respectively arranged at the two waists at the inner side of the concrete jacking pipe, and are arranged in the upper inner cavity of the hollow jacking pipe between the special-shaped freezing pipes at the two waists at the inner side at equal intervals under the condition that the number of the special-shaped freezing pipes exceeds two.
Further, the circulation cold source comprises a refrigerator, an outlet of the refrigerator is connected with a refrigerant liquid supply pipe through a low-temperature refrigerant circulation pump, an inlet of the refrigerator is connected with a refrigerant liquid return pipe, the refrigerant liquid supply pipe is respectively connected with a liquid inlet a and a liquid inlet b, and the refrigerant liquid return pipe is respectively connected with a liquid outlet a and a liquid outlet b.
A pipe curtain freezing test method for simulating underground water seepage comprises the following steps:
firstly, filling a soil layer in a test box to a preset pipe curtain freezing system height, then installing concrete jacking pipes with round freezing pipes and space jacking pipes with special-shaped freezing pipes on the soil layer of the test box at intervals, fixing the concrete jacking pipes and the space jacking pipes at intervals, enabling the central line directions of the concrete jacking pipes and the space jacking pipes to be perpendicular to water flows in return pipelines of an upstream cavity water storage tank and a downstream cavity water storage tank, and determining the distances between adjacent concrete jacking pipes and the space jacking pipes according to a test scheme;
step two, designing a monitoring scheme, arranging temperature sensors at the positions of the adjacent concrete jacking pipes, the adjacent empty jacking pipes and the tops of the jacking pipes, wherein the positions of the upstream and downstream of a pipe curtain freezing system are provided with all data transmission leads connected with the temperature sensors, and the data transmission leads are led out from the corners of a test box and are connected to a data collector of the monitoring system;
fixing temperature sensors between all concrete jacking pipes and empty jacking pipes and at the top, and filling soil in the test box after the temperature sensors are arranged at the upstream and downstream of the pipe curtain freezing system as well until the whole test box is filled, wherein the position of the temperature sensor cannot be changed in the soil filling process;
arranging the concrete jacking pipe and the empty jacking pipe according to test setting, connecting all the round freezing pipes and the special-shaped freezing pipes in series from end to end or in series according to different types, and then connecting the round freezing pipes and the special-shaped freezing pipes with an inlet and an outlet of a refrigerator; the test box and the constant temperature infiltration system are wrapped by using a heat insulation material, so that the dissipation of cold in the freezing process is prevented;
controlling the temperature of the constant-temperature water tank, ensuring the constant temperature of the constant-temperature infiltration system, calculating the pressure of the clean water supply pipe according to the designed groundwater infiltration speed, and adjusting the height of the constant-pressure water tank so as to ensure that the water pressure can form circulation;
step six, starting a clear water circulating pump to enable the constant-temperature permeation system to work, maintaining water in the external overflow pipe to return to the constant-temperature water tank, and controlling the constant-pressure water tank to be in a full-load state in the whole test process; at the moment, constant-temperature water in the clear water supply pipe enters the upstream cavity water storage tank, pressure grows in the upstream cavity water storage tank, then the constant-temperature water permeates into a soil layer of the test box and finally reaches the downstream cavity water storage tank, and returns to the constant-temperature water tank through the clear water return pipe to form circulation;
step seven, observing a cavity water storage tank at the downstream of the test box, waiting for the liquid level to rise to a clear water return pipe, and returning stable water flow to the constant-temperature water tank;
step ten: setting the liquid supply temperature of the refrigerator, starting a circulating cold source, and circulating a low-temperature refrigerant between a refrigerating pipe and the refrigerator;
step eleven: defining the position where the temperature sensor is set as a monitoring data observation control point, observing whether the temperature of the monitoring data observation control point is reduced to a freezing point, if so, ending the set of experiments, storing experimental data on a computer, and closing the refrigerator and the fresh water circulating pump; if the temperature of the control point is not reduced to the freezing point, increasing the number of freezing pipes participating in refrigerant circulation or increasing series grouping, and carrying out the test again until the freezing wall thickness with preset thickness is formed in the seepage soil layer.
The invention has the beneficial effects that: accurate control of groundwater temperature and velocity of flow is realized through setting up adjustable constant temperature water tank and constant pressure water tank, has reduced the experimental error that seepage water state unstability caused in the freezing process, is favorable to judging the influence of groundwater motion state to the curtain freezing effect more. Meanwhile, a stable seepage path is formed on the full section of the stratum by utilizing the water storage tank with the upstream cavity, so that the problem of local concentration of the underground water seepage path is solved, and the test result is more reliable. In addition, the dynamic regulation and control of the freezing effect of the pipe curtain under the seepage condition can be realized through different serial schemes of the freezing pipes in the jacking pipe, test soil bodies do not need to be replaced and filled again, a temperature sensor is arranged, and the best freezing pipe arrangement scheme for the problem of weakening the freezing wall due to groundwater seepage is convenient to find. The freezing effect of different freezing pipes in the seepage soil layer is obtained through simulation, and experimental researches can be carried out on the effects of different numbers of freezing pipes with different cross-sectional areas arranged inside the jacking pipe so as to cope with different groundwater flowing states in the stratum.
Drawings
Fig. 1 is a schematic plan view of the structure of the present invention.
FIG. 2 is a front view of the test chamber and a schematic diagram of a temperature monitoring system according to the present invention.
FIG. 3 is a schematic diagram of the connection of a circular freezing pipe and a special-shaped freezing pipe in the pipe curtain freezing system.
Reference numerals illustrate: 1-a constant temperature water tank; 2-a clean water circulation pump; 3-a constant pressure water tank; 4-a clean water supply pipe; 5-a clear water liquid return pipe; 6, an external overflow pipe; 7-a refrigerator; 8-a low-temperature refrigerant circulating pump; 9-a refrigerant liquid supply pipe; 10-a refrigerant liquid return pipe; 11-a test chamber; 12-concrete jacking pipe; 13-empty jacking pipe; 14-a circular freezing tube; 15-special-shaped freezing pipes; 16-heat insulation material; 17-an upstream cavity reservoir; 18-a downstream cavity reservoir; 19-a data collector; 20-data transmission leads; 21-temperature sensor.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings.
As shown in fig. 1, a pipe curtain freezing test device for simulating groundwater seepage is characterized in that: the device comprises a test box 11, wherein soil layers simulating underground states are filled in the test box 11, a pipe curtain freezing system is arranged in the test box 11, the pipe curtain freezing system comprises a plurality of concrete jacking pipes 12, empty jacking pipes 13, round freezing pipes 14 and special-shaped freezing pipes 15 which are horizontally arranged in the soil layers and penetrate through the soil layers at the front end and the rear end, and a temperature detection system is arranged around the pipe curtain freezing system; the left and right sides of the test box 11 are respectively provided with a constant temperature infiltration system for keeping the soil layer temperature, the pipe curtain freezing system is connected with a circulating cold source, and the outside of the test box 11 and the outside of the constant temperature infiltration system are respectively wrapped with a heat preservation material 16 so as to reduce the contact of external environment and ensure the whole temperature balance. The constant-temperature permeation system comprises an upstream cavity water storage tank 17 and a downstream cavity water storage tank 18 which are respectively and closely arranged on two sides of a soil layer of the test box 11, a constant-temperature water tank 1 and a constant-pressure water tank 3 which is arranged at the horizontal height of the test box 11, wherein the upstream cavity water storage tank 17 and the downstream cavity water storage tank 18 are communicated with two sides of a simulated soil layer of the test box 11, constant-temperature water tank 1 injects constant-temperature water into the constant-pressure water tank 3 through a clear water circulating pump 2, water is injected into the upstream cavity water storage tank 17 through a clear water supply pipe 4 at the bottom of the constant-temperature water tank 3 through gravity, and the constant-temperature water tank 1 is connected with the constant-temperature water tank 1 through a clear water return pipe 5; the constant pressure water tank 3 is provided with an overflow port connected with the constant temperature water tank 1 through an outer overflow pipe 6, and water in the upstream cavity water storage tank 17 moves to the downstream cavity water storage tank 18 under the pressure provided by the constant pressure water tank 3 to form seepage in a soil layer; the clear water supply pipe 4 and the clear water return pipe 5 are vertically arranged on the horizontal plane with the pipe curtain freezing system, so that constant-temperature water seepage in the soil layer tangentially moves the pipe curtain freezing system, and the outlet heights of the clear water supply pipe 4 and the clear water return pipe 5 are flush with the pipe curtain freezing system. The temperature detection system comprises a plurality of temperature sensors 21 and a data collector 19, wherein all the temperature sensors 21 are connected with the data collector 19 through data transmission leads 20, the temperature sensors 21 are arranged above all the pipes of the concrete jacking pipe 12, the empty jacking pipe 13, the round freezing pipe 14 and the special-shaped freezing pipe 15, and the temperature sensors 21 are arranged among all the adjacent concrete jacking pipe 12, the empty jacking pipe 13, the round freezing pipe 14 and the special-shaped freezing pipe 15 and used for detecting soil temperatures at different moments in the freezing process.
As shown in fig. 3, since horizontal drilling accuracy will not guarantee that driving a freezing pipe directly into a soil layer does not produce a low-cost position, it is necessary to provide the freezing pipe in the concrete jacking pipe 12 or the empty jacking pipe 13; therefore, the pipe curtain freezing system is also characterized in that the freezing pipes are arranged in a plurality of concrete jacking pipes 12 and empty jacking pipes 13 which are alternately and horizontally arranged;
the plurality of round freezing pipes 14 or special-shaped freezing pipes 13 are axially fixed in the inner wall of the concrete jacking pipe 12 or the hollow jacking pipe 13 in a welding mode, 10cm of the two ends of the round freezing pipes 14 or the special-shaped freezing pipes 13 are exposed out of the two ends of the concrete jacking pipe 12 or the hollow jacking pipe 13 for installing connecting pipes, and the diameter and wall thickness parameters of the concrete jacking pipe 12, the hollow jacking pipe 13, the round freezing pipes 14 and the special-shaped freezing pipes 15 are determined according to a freezing scheme. The round freezing pipes 14 are arranged in the concrete jacking pipe 12 at least two, are respectively arranged at two waists at the inner side of the concrete jacking pipe, and are arranged in the upper inner cavity of the concrete jacking pipe 12 between the round freezing pipes 14 at the two waists at the inner side at equal intervals under the condition of more than two round freezing pipes;
the special-shaped freezing pipes 13 are arranged at least two in the hollow jacking pipe 13 and are respectively arranged at two waists on the inner side of the concrete jacking pipe, and the special-shaped freezing pipes 13 are arranged in the upper inner cavity of the hollow jacking pipe 13 between the special-shaped freezing pipes 13 at the two waists on the inner side at equal intervals under the condition that the number of the special-shaped freezing pipes exceeds two.
The circulating cold source comprises a refrigerator 7, an outlet of the refrigerator 7 is connected with a refrigerant liquid supply pipe 9 through a low-temperature refrigerant circulating pump 8, an inlet of the refrigerator 7 is connected with a refrigerant liquid return pipe 10, the refrigerant liquid supply pipe 9 is respectively connected with a liquid inlet a and a liquid inlet b, and the refrigerant liquid return pipe 10 is respectively connected with a liquid outlet a and a liquid outlet b.
The first embodiment describes the test procedure with reference to 6 jacking pipes shown in fig. 1 in the accompanying drawings:
step one: the circular freezing pipes 14 are welded in the three concrete jacking pipes 12, the special-shaped freezing pipes 15 are welded in the three empty jacking pipes 13, two ends of each freezing pipe are exposed out of two ends of the jacking pipe by about 10cm, and the diameters and wall thickness parameters of the jacking pipe and the freezing pipes are determined according to a freezing scheme.
Step two: and filling concrete into the concrete jacking pipe 12 welded with the round freezing pipe 14, filling the whole jacking pipe, curing and hardening the concrete jacking pipe, wherein a cavity cannot exist at the end part of the hardened jacking pipe.
Step three: the concrete jacking pipe 12 and the empty jacking pipe 13 are installed in the test box 11 at intervals, the center line direction of the jacking pipe is perpendicular to the water flow direction, and the distance between adjacent jacking pipes is determined according to a test scheme.
Step four: thermocouple temperature sensors are arranged among adjacent jacking pipes, at the top of the jacking pipes, at the upstream and downstream of the jacking pipes and the like according to a monitoring scheme, and all data transmission leads 20 are led out from corners of the test box 11 and connected to a data collector 19 of the monitoring system. The total number of the temperature sensors is 17, the numbers are C1-C17 respectively, the temperature sensors are arranged among all jacking pipes, the temperature sensors are arranged at the top of the jacking pipes, and finally the temperature sensors are arranged at intervals at the upstream and the downstream, as shown in fig. 2.
Step five: after the position of the temperature sensor is fixed, filling soil in the test box 11, filling and compacting in layers, ensuring that no hole is left in the soil layer, preventing the influence on the freezing effect, and not changing the position of the sensor in the soil filling process until the whole test box 11 is filled. The soil layer is compacted anyway, so that the porosity is always present, and the water seepage is not a problem. Groundwater seepage at different speeds can still be realized by controlling the water pressure after compaction.
Step six: all freezing tubes were grouped according to a freezing protocol and connected with hoses, leaving one inlet and one outlet. Meanwhile, the heat insulation material 16 is closely adhered to the periphery and the top of the soil box, so that the dissipation of cold in the freezing process is prevented.
Step seven: the temperature of the constant-temperature water tank 1 is set, so that the liquid supply temperature of the clear water circulation system is ensured to be kept constant in the test process. Calculating the pressure of a clean water supply pipe according to the designed groundwater seepage speed, correspondingly adjusting the height of the constant-pressure water tank 3, connecting the clean water supply pipe 4 with an upstream cavity water storage tank 16, and connecting a clean water return pipe 5 with an upper water tank 17;
step eight: starting a clear water circulating pump 2, maintaining water in an external overflow pipe 6 to return to the constant-temperature water tank 1, and controlling the constant-pressure water tank 3 to be in a full-load state in the whole test process;
step nine: observing a cavity water storage tank 17 at the downstream of the test box, waiting for the liquid level to rise to the clear water return pipe 5, and returning stable water flow to the constant-temperature water tank;
step ten: a liquid supply pipe 9 and a liquid return pipe 10 of a refrigerant circulation system are connected with an inlet and an outlet of the freezing pipe in the step six to form a loop, the liquid supply temperature of a refrigerator is set, the refrigerator 7 is started, and a low-temperature refrigerant is circulated between the test box 11 and the refrigerator;
step eleven: in the test process, whether the temperature of the control point position is reduced to the freezing point or not is observed through monitoring data, if so, the test is ended, experimental data are stored in a computer, and the refrigerator 7 and the fresh water circulating pump 2 are closed;
step twelve: if the temperature of the control point is not reduced to the freezing point, the grouping scheme of the freezing pipes in the step six can be adjusted, the number of the freezing pipes participating in the refrigerant circulation is increased or the series grouping is increased, and the test is carried out again until the reliable freezing wall thickness is formed.
The above test method is only described in the preferred embodiments of the present invention, and does not limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solution of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims (7)
1. A pipe curtain freezing test device for simulating underground water seepage is characterized in that: the device comprises a test box (11), wherein soil layers simulating underground states are filled in the test box (11), a pipe curtain freezing system is arranged in the test box (11), the pipe curtain freezing system comprises a plurality of concrete jacking pipes (12), empty jacking pipes (13), round freezing pipes (14) and special-shaped freezing pipes (15) which are horizontally arranged in the soil layers and penetrate through the soil layers at the front end and the rear end, and a temperature detection system is arranged around the pipe curtain freezing system; the left side and the right side of the test box (11) are respectively provided with a constant temperature infiltration system for keeping the temperature of the soil layer, the pipe curtain freezing system is connected with a circulating cold source, and the outside of the test box (11) and the outside of the constant temperature infiltration system are respectively wrapped with a heat insulation material (16) so as to reduce the contact of external environment and ensure the whole temperature balance.
2. A pipe curtain freeze test device for simulating groundwater seepage according to claim 1, wherein: the constant-temperature permeation system comprises an upstream cavity water storage tank (17) and a downstream cavity water storage tank (18) which are respectively and closely arranged at two sides of a soil layer of the test box (11), a constant-temperature water tank (1) and a constant-pressure water tank (3) which is arranged at the horizontal height of the test box (11), wherein the upstream cavity water storage tank (17) and the downstream cavity water storage tank (18) are communicated with two sides of a simulated soil layer of the test box (11), constant-temperature water tank (1) injects constant-temperature water into the constant-pressure water tank (3) through a clear water circulating pump (2), the bottom of the constant-pressure water tank (3) injects water into the upstream cavity water storage tank (17) through a clear water supply pipe (4) by gravity, and the constant-temperature water tank (1) is connected with the constant-temperature water tank (1) through a clear water return pipe (5); an overflow port connected with the constant-temperature water tank (1) through an external overflow pipe (6) is arranged on the constant-pressure water tank (3), and water in the upstream cavity water storage tank (17) moves to the downstream cavity water storage tank (18) to form seepage in a soil layer under the pressure action provided by the constant-pressure water tank (3); the clear water supply pipe (4) and the clear water return pipe (5) are vertically arranged on the horizontal plane with the pipe curtain freezing system, so that constant-temperature water seepage in the soil layer tangentially moves the pipe curtain freezing system, and the heights of the outlets of the clear water supply pipe (4) and the clear water return pipe (5) are flush with the pipe curtain freezing system.
3. A pipe curtain freeze test device for simulating groundwater seepage according to claim 1, wherein: the temperature detection system comprises a plurality of temperature sensors (21) and a data collector (19), all the temperature sensors (21) are connected with the data collector (19) through data transmission leads (20), wherein the temperature sensors (21) are arranged above all concrete jacking pipes (12), empty jacking pipes (13), round freezing pipes (14) and special-shaped freezing pipes (15), and the temperature sensors (21) are arranged between all adjacent concrete jacking pipes (12), empty jacking pipes (13), round freezing pipes (14) and special-shaped freezing pipes (15) and used for detecting soil temperatures at different moments in the freezing process.
4. A pipe curtain freeze test device for simulating groundwater seepage according to claim 1, wherein: the horizontal drilling precision cannot ensure that the frozen pipe is directly driven into the soil layer without generating low position, so that the frozen pipe is required to be arranged in the concrete jacking pipe (12) or the empty jacking pipe (13); therefore, the pipe curtain freezing system is also characterized in that the freezing pipes are arranged in a plurality of concrete jacking pipes (12) and empty jacking pipes (13) which are alternately and horizontally arranged;
the plurality of round freezing pipes (14) or special-shaped freezing pipes (13) are axially fixed in the inner wall of the concrete jacking pipe (12) or the hollow jacking pipe (13) in a welding mode, the two ends of the round freezing pipes (14) and the special-shaped freezing pipes (13) are exposed out of 10cm of the two ends of the concrete jacking pipe (12) or the hollow jacking pipe (13) for installing connecting pipes, and the diameters and wall thickness parameters of the concrete jacking pipe (12), the hollow jacking pipe (13), the round freezing pipes (14) and the special-shaped freezing pipes (15) are determined according to a freezing scheme.
5. The apparatus for simulating freeze test on a tube sheet for groundwater seepage according to claim 4, wherein: the circular freezing pipes (14) are arranged in the concrete jacking pipe (12) at least two, are respectively arranged at two waists at the inner side of the concrete jacking pipe, and are arranged in the upper inner cavity of the concrete jacking pipe (12) between the circular freezing pipes (14) at the two waists at the inner side at equal intervals under the condition of more than two circular freezing pipes;
the special-shaped freezing pipes (13) are arranged in the hollow jacking pipe (13) at least two, are respectively arranged at two waists at the inner side of the concrete jacking pipe, and are arranged in the upper inner cavity of the hollow jacking pipe (13) between the special-shaped freezing pipes (13) at the two waists at the inner side at equal intervals under the condition that the number of the special-shaped freezing pipes exceeds two.
6. The apparatus for simulating freeze test on a tube sheet for groundwater seepage according to claim 4, wherein: the circulating cold source comprises a refrigerator (7), a refrigerant liquid supply pipe (9) is connected to an outlet of the refrigerator (7) through a low-temperature refrigerant circulating pump (8), a refrigerant liquid return pipe (10) is connected to an inlet of the refrigerator (7), the refrigerant liquid supply pipe (9) is connected with a liquid inlet a and a liquid inlet b respectively, and the refrigerant liquid return pipe (10) is connected with a liquid outlet a and a liquid outlet b respectively.
7. A test method of a pipe curtain freezing test apparatus for simulating groundwater seepage according to any one of claims 1 to 6, characterized by the steps of:
firstly, filling soil layers in a test box (11) to a preset pipe curtain freezing system height, then installing concrete jacking pipes (12) provided with round freezing pipes (14) and empty jacking pipes (13) provided with special-shaped freezing pipes (15) on the soil layers of the test box (11) at intervals and fixing, wherein the central line directions of the concrete jacking pipes (12) and the empty jacking pipes (13) are perpendicular to water flows in return pipelines of an upstream cavity water storage tank (17) and a downstream cavity water storage tank (18), and the distances between adjacent concrete jacking pipes (12) and the empty jacking pipes (13) are determined according to a test scheme;
step two, designing a monitoring scheme, arranging temperature sensors (21) at positions between adjacent concrete jacking pipes (12) and empty jacking pipes (13) and at the tops of the jacking pipes, wherein all data transmission leads (20) connected with the temperature sensors (21) are led out from the corners of a test box (11) and connected to a data collector (19) of a monitoring system;
fixing temperature sensors (21) between all concrete jacking pipes (12) and empty jacking pipes (13) and at the top, and after the temperature sensors (21) are arranged at the upstream and downstream of the pipe curtain freezing system, filling soil in the test box (11) until the whole test box (11) is filled, wherein the position of the temperature sensors (21) cannot be changed in the soil filling process;
arranging and arranging concrete jacking pipes (12) and empty jacking pipes (13) according to test setting, and selecting all round freezing pipes (14) and special-shaped freezing pipes (13) to be connected in series end to end or in series according to types, and then connecting the round freezing pipes and the special-shaped freezing pipes with an inlet and an outlet of a refrigerator (7); the test box (11) and the constant temperature infiltration system are wrapped by using a heat insulation material (16) to prevent cold dissipation in the freezing process;
controlling the temperature of the constant-temperature water tank (1), ensuring the constant temperature of the constant-temperature infiltration system, calculating the pressure of the clean water supply pipe according to the designed groundwater infiltration speed, and adjusting the height of the constant-pressure water tank (3) so as to ensure that the water pressure can form circulation;
step six, starting a clear water circulating pump (2) to enable the constant temperature infiltration system to work, maintaining water in the external overflow pipe (6) to return to the constant temperature water tank (1), and controlling the constant pressure water tank (3) to be in a full-load state in the whole test process; at the moment, constant-temperature water in the clear water supply pipe (4) enters an upstream cavity water storage tank (17) and generates pressure in the upstream cavity water storage tank (17), then the constant-temperature water permeates into a soil layer of the test box (11) and finally reaches a downstream cavity water storage tank (18), and returns to the constant-temperature water tank (1) through the clear water return pipe (5) to form circulation;
step seven, observing a cavity water storage tank (18) at the downstream of the test box, waiting for the liquid level to rise to a clear water return pipe (5), and returning stable water flow to the constant-temperature water tank (1);
step ten: setting the liquid supply temperature of a refrigerator (7), starting a circulating cold source, and circulating a low-temperature refrigerant between a freezing pipe and the refrigerator;
step eleven: defining the position where the temperature sensor (21) is set as a monitoring data observation control point, observing whether the temperature of the monitoring data observation control point is reduced to the freezing point, if so, ending the group of tests, storing the experimental data on a computer, and closing the refrigerator (7) and the fresh water circulating pump (2); if the temperature of the control point is not reduced to the freezing point, increasing the number of freezing pipes participating in refrigerant circulation or increasing series grouping, and carrying out the test again until the freezing wall thickness with preset thickness is formed in the seepage soil layer.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN117571596A (en) * | 2023-11-30 | 2024-02-20 | 北京市科学技术研究院 | Buried pipeline structural hidden trouble simulation test device and method based on environment |
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| CN117571596A (en) * | 2023-11-30 | 2024-02-20 | 北京市科学技术研究院 | Buried pipeline structural hidden trouble simulation test device and method based on environment |
| CN117571596B (en) * | 2023-11-30 | 2024-04-16 | 北京市科学技术研究院 | Buried pipeline structural hidden trouble simulation test device and method based on environment |
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