CN115389182B - Simulation test device for measuring buoyancy of bottom plate of underground station, installation and test method - Google Patents
Simulation test device for measuring buoyancy of bottom plate of underground station, installation and test methodInfo
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- CN115389182B CN115389182B CN202210988005.4A CN202210988005A CN115389182B CN 115389182 B CN115389182 B CN 115389182B CN 202210988005 A CN202210988005 A CN 202210988005A CN 115389182 B CN115389182 B CN 115389182B
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Abstract
The invention discloses a simulation test device for measuring the buoyancy of a bottom plate of an underground station, which comprises a reinforced concrete test pool, wherein the reinforced concrete test pool is used for accommodating the soil body of a station site of a subway car, a steel inner cylinder is vertically arranged in the middle part of the test pool, a first blind ditch is arranged below the test pool, a steel wire mesh is arranged on the top surface of the first blind ditch, and the edge of the bottom of the steel inner cylinder is fixed with the steel wire mesh; the outer side of the steel inner cylinder is provided with a second blind ditch, and the two blind ditches are communicated with the outside of the test pool through corresponding drain pipes and water level pipes; the bottom of the steel inner cylinder is connected with the buoyancy testing bottom plate through the bottom plate connecting assembly, a plurality of pressure sensors and displacement sensors are arranged on the buoyancy testing bottom plate, the bottom of a steel structure support vertically arranged in the steel inner cylinder is connected with the pressure sensors, and the top of the steel structure support is connected with the top supporting structure. The invention also discloses a corresponding installation and test method. The invention can effectively simulate the action of the underground station bottom plate and water under the blind drain condition, and provides a theoretical basis for the anti-floating stable design of the underground station structure of the subway.
Description
Technical Field
The invention belongs to the technical field of anti-floating of underground stations, and particularly relates to a simulation test device for measuring the buoyancy of a bottom plate of an underground station, and an installation and test method.
Background
The underground station of the subway has large burial depth, the load on the upper part of the structure is smaller, especially in the area with shallow groundwater level, the influence of groundwater buoyancy is larger, and the anti-floating problem of the underground structure is prominent. On the premise of saving resources and energy and having little influence on the surrounding environment, the anti-floating problem of the structure is solved, and is one of the key problems which must be solved in the process of greatly developing underground space. The active anti-floating method for releasing water and lowering pressure has the advantages of simple and safe construction, relatively low cost and strong adaptability, and is increasingly applied to subway stations with large burial depths and complex geological conditions. However, no reasonable theoretical method is available for representing the active anti-floating water buoyancy, which is a great difficulty in restricting the existing anti-floating analysis of the water drainage pressure reduction, such as over-high value, increased investment of engineering projects, and low value, which can cause that the anti-floating stability of the structure cannot meet the requirement or the upper structure is damaged, and brings great risk to the safety of subway stations. Therefore, the research on the formation mechanism and the calculation method of the subway station water buoyancy under the blind drain condition has important significance, wherein accurate testing and evaluation of the buoyancy performance of the station bottom plate are very necessary key problems.
In order to obtain the water buoyancy parameters of the bottom plate of the underground station, the influence conditions of different pressure water heads and different drainage modes are observed, the change of the water buoyancy of the bottom plate of the station is quantitatively analyzed under the conditions, and no equipment and method for testing the water buoyancy of the bottom plate under the blind drain condition are found in the current indoor and outdoor water buoyancy test.
In summary, if the magnitude of the water buoyancy of the subway station under the condition of the blind drain needs to be truly and effectively calculated, the accurate water buoyancy action relation and performance parameters are obtained, and it is particularly important to develop a test device capable of testing the water buoyancy mechanical parameters of the engineering instance and problem.
Disclosure of Invention
Aiming at one or more of the defects or improvement demands of the prior art, the invention provides a simulation test device, installation and test method for measuring the buoyancy of the underground station bottom plate, which can effectively simulate the action of the underground station bottom plate and water under the condition of blind drain and provide a theoretical basis for the anti-floating stable design of the underground station structure of the subway.
In order to achieve the above object, according to a first aspect of the present invention, there is provided a simulation test apparatus for measuring buoyancy of a floor of an underground station, comprising a reinforced concrete test cell;
the reinforced concrete test pool is internally filled with a clay layer and a sand layer from bottom to top, the top of the sand layer is provided with a pebble layer, the middle part in the reinforced concrete test pool is vertically provided with a steel inner cylinder, the bottom of the steel inner cylinder is arranged in the clay layer, and the top of the steel inner cylinder is not lower than the elevation of the top surface of the sand layer;
A first blind ditch is arranged below the steel inner cylinder, a steel wire mesh is arranged on the top surface of the first blind ditch, and the edge of the bottom of the steel inner cylinder is fixed with the steel wire mesh; the outer side of the steel inner cylinder is provided with a second blind ditch, and the second blind ditch is arranged in the clay layer; the first blind ditch and the second blind ditch are communicated with the outside of the reinforced concrete test pool through corresponding drain pipes and water level pipes;
The bottom of the steel inner cylinder is connected with a buoyancy testing bottom plate through a bottom plate connecting assembly, the joint of the steel inner cylinder and the buoyancy testing bottom plate is sealed, and the buoyancy testing bottom plate can vertically and limitedly move in the bottom plate connecting assembly;
Be equipped with a plurality of pressure sensor and displacement sensor on the buoyancy test bottom plate, wherein pressure sensor is fixed in its top, and pressure sensor accessible compression set deformation measures current pressure value, the steel structure support bottom of vertical setting in the steel inner tube with pressure sensor connects, and top bearing structure are connected, top bearing structure is fixed in reinforced concrete test pool wall top surface.
As a further improvement of the invention, a first steel plate strip and a second steel plate strip are vertically arranged at intervals on the inner side of the bottom of the steel inner cylinder, steel rings (803) are arranged on the inner sides of the first steel plate strip and the second steel plate strip, and the buoyancy testing bottom plate is fixedly arranged between the steel rings;
and a limiting pin is fixed in the annular groove of the steel ring, and one end of the limiting pin is positioned between the first steel plate strip and the second steel plate strip.
As a further improvement of the invention, the bottom surface of the steel ring and the bottom surface of the first steel plate strip are provided with flexible water stop strips, and the flexible water stop strips are connected with the two through a bolt component; meanwhile, the top surfaces of the steel ring and the second steel plate strip are provided with flexible water stop strips, and the flexible water stop strips are connected with the steel ring and the second steel plate strip through a bolt assembly.
As a further improvement of the invention, the water level pipes connected with the first blind ditches and the second blind ditches are communicated with the corresponding water level identification plates on the outer wall of the reinforced concrete test pool at the other end, so that the corresponding water levels can be intuitively read through reading.
As a further improvement of the invention, the drain pipe connected with the first blind ditch and the second blind ditch is provided with an independent valve outside the reinforced concrete test pool.
As a further improvement of the invention, the reinforced concrete test pool is externally provided with steps, so that the bottoms of the water level identification plates can be conveniently read, and the steel structure support is provided with steps, so that test staff can conveniently reach the bottom of the steel inner cylinder.
According to a second aspect of the present invention, there is provided a construction method of the simulation test apparatus for measuring the buoyancy of a floor of an underground station, comprising the steps of:
1) Constructing a reinforced concrete test pool at a test site;
2) After the concrete strength of the reinforced concrete test pool reaches the design strength, burying a clay layer in the test pool by adopting a layered compaction method;
3) After the clay layer is buried to the designed elevation, a first blind ditch at the bottom of the steel inner cylinder is manufactured in the test pool, and a first water level pipe and a first drain pipe with a valve are arranged at the bottom of the blind ditch;
4) Arranging a steel wire mesh on the top surface of the first blind drain, and installing a steel inner cylinder on the accurately positioned steel wire mesh;
5) After the steel inner cylinder is installed, a soil clay layer is continuously filled between the steel inner cylinder and the reinforced concrete test pool, a second annular blind ditch is arranged at a corresponding design position on the outer side of the steel inner cylinder, and a second water level pipe and a second drain pipe with a valve are arranged at the bottom of the second blind ditch;
6) Continuously filling a clay layer, and filling a sand layer and a pebble layer above the clay layer;
7) After filling soil in the reinforced concrete test pool reaches a designed elevation, a bottom plate connecting assembly and a buoyancy testing bottom plate are arranged on the inner wall of the steel inner cylinder, a plurality of displacement sensors are arranged at the bottom of the buoyancy testing bottom plate, and a plurality of pressure sensors are arranged at the top of the buoyancy testing bottom plate;
8) And hoisting a steel structure bracket in the steel inner cylinder, and respectively connecting the top and the bottom of the steel structure bracket with the top supporting structure and the pressure sensor.
As a further improvement of the invention, after the pressure sensor and the displacement sensor are installed, the cable wires of each sensor are connected into the corresponding data acquisition box outside the reinforced concrete test pool.
According to a third aspect of the present invention, there is provided a test method of the simulation test apparatus for measuring the buoyancy of a floor of an underground station, comprising the steps of:
S1: backfilling the rock-soil body retrieved on site to the bottom of the first blind ditch according to the geological condition on site;
S2: injecting water step by step into the reinforced concrete test pool, acquiring each pressure water head H according to the stable reading of the first water level pipe, and calculating the bottom water pressure values under different pressure water heads according to the formula (1):
F=γha type (1)
In the formula (1), F is the bottom water pressure value under different pressure water heads, gamma is the weight of water, H is the pressure water head, and A is the buoyancy test bottom plate area;
S3: recording readings N of pressure sensors under different pressure heads, respectively obtaining friction forces F between a buoyancy test bottom plate and the side wall of the steel inner cylinder under different pressure heads through a formula (2), and drawing a relation curve of bottom water pressure values F 1 and the friction forces F under different pressure heads;
f 1 =n+g+f (2)
In the formula (2), F 1 is the bottom water pressure value under different pressure heads, G is the weight of the buoyancy test bottom plate, and N is the reading of the pressure sensor under different pressure heads;
S4: draining water in the reinforced concrete test pool, and continuously backfilling the rock and soil retrieved in the site to the required elevation of the reinforced concrete test pool by referring to the geological condition of the site and compacting;
s5: injecting water into the pebble layer and keeping the pebble layer in a full water state;
S6: when the readings of the pressure sensor and the displacement sensor are stable, namely the rock and soil body is saturated, the friction force F under the working condition of the full water head is obtained according to the step S3, the reading N of the pressure sensor at the moment is recorded, and the buoyancy F 2 borne by the buoyancy test bottom plate under the working condition of the full water head is obtained according to the step S;
f 2 =n+g+f (3)
In the formula (3), F 2 is the buoyancy force born by the buoyancy force testing bottom plate, F is the friction force between the buoyancy force testing bottom plate and the side wall of the steel inner cylinder under different pressure water heads, G is the weight of the buoyancy force testing bottom plate, and N is the reading of the pressure sensor under different pressure water heads;
S7: injecting water to keep the pebble layer in a water-full state, and selectively opening drain pipe valves of the first blind ditch and/or the second blind ditch according to the situation to drain water; and recording the water discharge time and the water discharge quantity of the two blind ditches under the working conditions of independent water discharge and combined water discharge, and continuously obtaining the buoyancy F 2 of the buoyancy test bottom plate under the working conditions of each pressure water head according to the step S6.
In general, the above technical solutions conceived by the present invention have the following beneficial effects compared with the prior art:
(1) The simulation test device for measuring the buoyancy of the bottom plate of the underground station adopts the reinforced concrete test Chi Chengfang to test the soil body of the station site of the subway vehicle, forms the test pool body capable of testing the buoyancy of the bottom plate of the underground station under the drainage condition of the blind ditch, can truly and effectively simulate the action of the bottom plate of the underground station and water under the drainage condition of the blind ditch by utilizing the pressure sensor and the displacement sensor, acquires the mechanical parameters between the bottom plate and the water, obtains the relation of the accurate drainage mode, the drainage quantity and the action of the water buoyancy, and provides a foundation for the formation mechanism and the calculation method of the water buoyancy of the subway station under the drainage condition of the blind ditch.
(2) The simulation test method for measuring the bottom plate buoyancy of the underground station can provide theoretical basis and technical support for the anti-floating stable design of the underground station structure of the subway, and can also provide reference for the anti-floating stable design of engineering structures such as municipal underground engineering, underground space and the like.
Drawings
FIG. 1 is a schematic diagram of a simulation test device for measuring the buoyancy of a bottom plate of an underground station according to an embodiment of the invention;
FIG. 2 is an enlarged view of a portion of the steel inner barrel bottom connecting structure of FIG. 1 in accordance with an embodiment of the present invention;
FIG. 3 is an enlarged view of a connection structure between a buoyancy testing bottom plate and a steel inner cylinder, which is related to a simulation test device for measuring the buoyancy of a bottom plate of an underground station, according to an embodiment of the invention;
FIG. 4 is a plan view of a connection between a buoyancy testing base plate and a steel inner cylinder of a simulation test device for measuring the buoyancy of a base plate of an underground station according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a loading truss assembly involved in a simulation test apparatus for measuring the buoyancy of a bottom plate of an underground station according to an embodiment of the present invention;
FIG. 6 is a schematic view of a steel truss structure involved in a simulation test device for measuring the buoyancy of a bottom plate of an underground station according to an embodiment of the present invention;
Fig. 7 is a schematic plan view of a top support structure involved in a simulation test apparatus for measuring the buoyancy of a bottom plate of an underground station according to an embodiment of the present invention.
Like reference numerals denote like technical features throughout the drawings, in particular: 1-reinforced concrete test pool, 2-clay layer, 3-sand layer, 4-first blind ditch, 5-steel inner cylinder, 6-second blind ditch, 7-steel wire mesh, 8-bottom plate connecting component, 9-buoyancy test bottom plate, 10-pressure sensor, 11-displacement sensor, 12-steel structure bracket, 13-first water level pipe, 14-first drain pipe, 15-second water level pipe, 16-second drain pipe, 17-water level signboard, 18-pebble layer, 19-loading truss, 20-first valve and 21-second valve; 801-first steel plate strips, 802-second steel plate strips, 803-steel rings, 804-limiting pins, 805-flexible water stop strips and 806-bolt assemblies; 191-truss, 192-angle steel, 193-channel steel, 194-first welding lacing plate, 195-second welding lacing plate, 196-screw assembly.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In the present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.
The invention provides a simulation test device for measuring the buoyancy of a bottom plate of an underground station under the condition of blind drain, as shown in figure 1, the simulation test device for measuring the buoyancy of the bottom plate of the underground station comprises a reinforced concrete test pool 1, a clay layer 2 is filled below the reinforced concrete test pool 1, a sand layer 3 is filled above the clay layer 2, preferably, a pebble layer 18 is also arranged in the sand layer 3, the pebble layer 18 is arranged at the top of the sand layer 3, and the elevation of the pebble layer 18 is the same as that of the top surface of the sand layer 3. The clay layer 2, the sand layer 3 and the pebble layer 18 are all retrieved from the underground station site, the steel inner cylinder 5 is vertically arranged in the middle part in the reinforced concrete test pool 1, the bottom of the steel inner cylinder 5 is arranged in the clay layer 2, and the top of the steel inner cylinder is not lower than the top surface elevation of the sand layer 3.
The steel inner tube 5 below is equipped with first french drain 4, and first french drain 4 top surface is equipped with wire netting 7, and steel inner tube 5 bottom edge is fixed with wire netting 7. The steel wire mesh 7 is used as a base for installing the steel inner cylinder 5, so that the position of the steel inner cylinder is ensured not to deviate during installation; on the other hand, set up the steel wire netting between steel inner tube and first french drain, can stop the inside stone of first french drain and the buoyancy test bottom plate 9 of steel inner tube bottom to produce the contact, do not influence the water in the first french drain again simultaneously and buoyancy test bottom plate 9 contact.
The outer side of the steel inner cylinder 5 is provided with a second annular blind ditch 6, and the second blind ditch 6 is arranged in the clay layer 2. The first blind ditch 4 is communicated with a first water level pipe 13 and a first drain pipe 14, one end of the first water level pipe 13 and one end of the first drain pipe 14 are connected with the bottom of the first blind ditch 4, the other end extends out of the reinforced concrete test pool 1, and the end is provided with a first valve 20. The second blind ditch 6 is communicated with a second water level pipe 15 and a second drain pipe 16, one end of the second water level pipe 15 and one end of the second drain pipe 16 are connected with the bottom of the second blind ditch 6, the other end extends out of the reinforced concrete test pool 1, and the end is provided with a second valve 21.
The first water level pipe 13 and the second water level pipe 15 are communicated with corresponding water level identification plates 17 on the outer wall of the reinforced concrete test tank 1, and corresponding water levels can be visually seen through reading.
The first blind ditch and the second blind ditch are used for draining and decompressing, wherein the first blind ditch is arranged at the bottom of the device, the second blind ditch is arranged on the side wall of the middle of the device, the water level pipe is used for monitoring the water head change conditions at different positions in the test pool, the drain pipes are used for draining, the drain pipes are all provided with valves for controlling the drainage mode and the drainage amount, and the signboard is used for fixing the water level pipes at different positions outside the test pool, so that the water level change conditions are more intuitively compared.
The steel inner cylinder 5 is preferably cylindrical, and correspondingly, the first blind ditch is cylindrical at the bottom of the steel inner cylinder, the second blind ditch is arranged on the side wall of the steel inner cylinder and is circular, and as shown in fig. 4, the bottom of the steel inner cylinder is connected with the circular buoyancy testing bottom plate 9 through the bottom plate connecting assembly 8 along the circumferential direction.
As further shown in connection with fig. 1-3, the floor connection assembly 8 includes a first steel strap 801, a second steel strap 802, a steel ring 803, a stop pin 804, a flexible water stop bar 805, and a bolt assembly 806. Specifically, a first steel plate strip 801 and a second steel plate strip 802 are arranged at intervals on the inner side of the bottom of the steel inner cylinder 5, and are preferably welded with the steel inner cylinder; the first steel strip 801 and the second steel strip 802 are vertically spaced apart, and in one embodiment of the invention shown in the drawings, the second steel strip 802 is positioned above the first steel strip 801 with the bottom surface of the first steel strip 801 being level with the bottom surface of the inner steel cylinder 5, and the second steel strip 802 is further preferably spaced 30mm from the first steel strip 801.
The inner sides of the first steel plate strip 801 and the second steel plate strip 802 are provided with steel rings 803, the top surface of the steel rings 803 is preferably flat with the top surface of the second steel plate strip 802, the bottom surface of the steel rings 803 is preferably flat with the bottom surface of the first steel plate strip 801, the top surfaces of the steel rings 803 and the top surface of the second steel plate strip 802 are provided with flexible water stop strips 805, the flexible water stop strips 805 are simultaneously connected with the second steel plate strip 802 and the steel rings 803 through corresponding bolt assemblies 806, the bottom surfaces of the steel rings 803 and the bottom surfaces of the first steel plate strip 801 are also provided with flexible water stop strips 805, and the flexible water stop strips 805 are simultaneously connected with the first steel plate strip 801 and the steel rings 803 through corresponding bolt assemblies 806. Adopt the waterstop stagnant water between buoyancy test bottom plate and the billet on the steel inner tube, can prevent that the rivers infiltration in soil body from the steel inner tube to under the buoyancy effect, when buoyancy test bottom plate 9 and steel ring 803 vertical movement can be guaranteed to flexible waterstop, have certain buffer space.
The buoyancy testing base plate 9 is disposed between and preferably welded to the steel rings 803. In order to ensure that a certain movable space exists between the buoyancy testing bottom plate and the steel inner cylinder, and simultaneously ensure that the movement range of the buoyancy testing bottom plate cannot be overlarge, a limiting pin 804 is fixed in a circumferential groove of the steel ring 803, and one end of the limiting pin 804 is positioned between the first steel plate strip 801 and the second steel plate strip 802, so that the buoyancy testing bottom plate 9 and the steel ring 803 are limited through the limiting pin 804 when vertically moving under the buoyancy effect.
The buoyancy testing bottom plate 9 is provided with a plurality of pressure sensors 10 and displacement sensors 11, the pressure sensors 10 are used for testing the buoyancy on the bottom plate, and the displacement sensors 11 are used for measuring the displacement value of the buoyancy testing bottom plate under the action of water buoyancy. The pressure sensor 10 is arranged on the top surface of the buoyancy testing bottom plate 9 and is connected with the steel structure support 12 through the pressure sensor 10, the top of the steel structure support 12 is fixed through a top supporting structure, the bottom of the steel structure support is connected with the pressure sensor 10, the top supporting structure is fixed on the top surface of the tank wall of the reinforced concrete testing tank 1, the steel structure support and the top supporting structure are used for providing buoyancy counter force so as to measure buoyancy, and meanwhile, a step is arranged on the steel structure support, so that test personnel can conveniently reach the bottom of the steel inner cylinder to perform construction.
It should be noted that, the pressure sensor 10 may measure the current pressure value through compression deformation, and the pressure sensor 10 may sense the corresponding pressure value while being compressed in the process of floating the buoyancy test base plate 9.
In one embodiment of the present invention shown in the drawings, a displacement sensor 11 is preferably provided at the bottom of the buoyancy test base plate 9, by which it is determined whether the buoyancy test base plate 9 is displaced. It should be noted that the data measured in the pressure sensor 10 is valid only on the premise that the displacement sensor 11 is displaced from the initial value, that is, sliding friction is generated between the buoyancy test base plate and the steel inner cylinder.
In one non-limiting embodiment, the top support structure comprises a steel structural truss (as shown in fig. 6) and a load truss 19 (as shown in fig. 5), wherein the load truss 19 comprises a truss 191, angle steel 192, channel 193, first weld gusset plate 194, and second weld gusset plate 195. The truss 191 is horizontally arranged, the channel steel 193 is vertically arranged at two ends of the truss 191, oblique angle steel 192 is arranged between the truss 191 and the channel steel 193, and two ends of the angle steel 192 are respectively fixed with the truss 191 and the channel steel 193 through a first welding lacing plate 194 and a second welding lacing plate 195. As shown in fig. 7, a plurality of steel structure trusses are fixed on the top of the wall of the reinforced concrete test tank 1, a loading truss 19 is fixed on the steel structure trusses, and a truss 191 is connected with the top of the steel structure bracket 12 through a screw assembly 196. It should be understood that the above description provides only one embodiment, and the specific manner in which the top support structure is provided is not particularly limited in the present invention, so long as the top of the steel structural brace 12 can be stably connected.
Illustratively, the test cell of the present invention has a planar dimension of 7.750m x 7.750m and a depth of 6m; the round steel inner cylinder is used for simulating a subway station, the outer diameter of the steel inner cylinder is 1.5m, the height is 4.15m, and the thickness of the steel inner cylinder embedded into a soil body is 4m. The sizes of the reinforced concrete test pool, the size of the round steel inner cylinder, the size of the buoyancy test bottom plate, the size of the blind ditch, the size of the water level pipe, the size of the drain pipe, the size of the signboard and the like can be adjusted according to the requirements.
According to the invention, a reinforced concrete test Chi Chengfang is adopted for a subway station site soil body (clay, sand and pebbles are arranged on a site monitoring section soil body), so that a test pool body capable of testing the buoyancy of the bottom plate of the underground station under the drainage of the blind ditch is formed, and the pressure sensor and the displacement sensor are utilized to truly and effectively simulate the action of the bottom plate of the underground station and water under the drainage condition of the blind ditch, so that the mechanical parameters between the bottom plate and the water are obtained, the relation of an accurate drainage mode, the drainage amount and the action of the water buoyancy is obtained, and a foundation is provided for the formation mechanism and the calculation method of the water buoyancy of the subway station under the drainage condition of the blind ditch.
Further, the invention relates to a simulation test device for measuring the buoyancy of a bottom plate of an underground station, which comprises the following steps:
(1) Constructing a reinforced concrete test pool 1 at a test site;
After the test site is constructed and leveled, paving a concrete cushion layer on the surface of the test site; binding reinforcing steel bars of a bottom plate of the test pool and pouring concrete of the bottom plate according to the design; after the strength of the bottom plate concrete reaches the design strength, binding reinforcing steel bars of the pool wall of the test pool and pouring concrete of the pool wall;
(2) After the concrete strength of the reinforced concrete test pool reaches the design strength, burying a clay layer 2 in the test pool by adopting a layered compaction method;
(3) After the clay layer 2 is buried to the designed elevation, a first blind ditch 4 at the bottom of the steel inner cylinder is manufactured in the test pool, and a first water level pipe 13 and a first drain pipe 14 with a valve are arranged at the bottom of the blind ditch;
(4) A steel wire mesh 7 is arranged on the top surface of the first blind drain 4, the steel wire mesh 7 is used as a mounting base of the steel inner cylinder 5, and the steel inner cylinder 5 is mounted on the accurately positioned steel wire mesh;
(5) After the installation of the steel inner cylinder 5 is completed, continuously filling a clay layer 2 between the steel inner cylinder 5 and the reinforced concrete test pool 1, arranging a second annular blind ditch 6 at a corresponding design position on the outer side of the steel inner cylinder 5, and arranging a second water level pipe 15 and a second drain pipe 16 with a valve at the bottom of the second blind ditch 6;
(6) Continuing to fill the clay layer 2, and filling the sand layer 3 and the pebble layer 18 above the clay layer 2;
(7) After the reinforced concrete test pool 1 is filled with soil to reach a designed elevation, a bottom plate connecting assembly 8 is arranged on the inner wall of the steel inner cylinder 5, a buoyancy test bottom plate 9 is arranged, a plurality of displacement sensors 11 are arranged at the bottom of the buoyancy test bottom plate 9, and a plurality of pressure sensors 10 are arranged at the top;
(8) Hoisting a steel structure bracket 12 in the steel inner cylinder, and respectively connecting the top and the bottom of the steel structure bracket with a top supporting structure and a pressure sensor 10; the bottom of the steel structure support 12 is fixed on the buoyancy testing bottom plate 9 through the pressure sensor 10, the top of the steel structure support 12 is fixed on a top supporting structure through a bolt assembly, and the top supporting structure is fixed on the top of the pool wall of the reinforced concrete testing pool 1.
In addition, after the pressure sensor and the displacement sensor in the test pool are installed, connecting cables of various sensors into corresponding data acquisition boxes outside the reinforced concrete test pool; in order to read the water level and the water discharge amount at the blind drain intuitively, a water level pipe extends forwards in the horizontal direction, passes through the pool wall of the test pool to the outer side of the test pool, and a water level signboard 17 is manufactured on the outer side of the test pool.
Further, aiming at the simulation test device for measuring the buoyancy of the bottom plate of the underground station, the invention provides a simulation test method, which comprises the following steps:
S1: backfilling the rock-soil body retrieved on site to the bottom of the first blind ditch 4 according to the geological condition on site;
S2: injecting water step by step into the reinforced concrete test pool 1, acquiring each pressure water head H according to the stable reading of the first water level pipe 13, and calculating the bottom water pressure values under different pressure water heads according to the formula (1):
F=γha type (1)
In the formula (1), F is the bottom water pressure value under different pressure water heads, gamma is the weight of water, H is the pressure water head, and A is the buoyancy test bottom plate area;
for example, the gradient of the pressure water heads can be set to be 1m, 1.5m, 2m, 2.5m, 3m, 3.5m, 4m, 4.5m and 5m, other pressure water head gradients can be set according to actual conditions, and the bottom water pressure value F under different pressure water head heights is calculated;
S3: and recording readings N of the pressure sensor 10 under different pressure heads, respectively obtaining friction force F between the buoyancy test bottom plate 9 and the side wall of the steel inner cylinder 5 under different pressure heads through the formula (2), and drawing a relation curve of a bottom water pressure value F 1 and the friction force F under different pressure heads.
F 1 =n+g+f (2)
In the formula (2), F 1 is the bottom water pressure value under different pressure heads, G is the weight of the buoyancy test bottom plate 9, and N is the reading of the pressure sensor 10 under different pressure heads;
S4: draining water in the reinforced concrete test pool 1, and continuously backfilling the rock and soil retrieved in the site to the required elevation of the reinforced concrete test pool 1 by referring to the geological condition of the site and compacting;
s5: injecting water into the pebble layer 18 and keeping the pebble layer in a full water state, and preferably pumping air from the top of the test pool by adopting a vacuum pump to enable water to freely infiltrate downwards so as to accelerate saturated rock-soil mass;
S6: when the readings of the pressure sensor 10 and the displacement sensor 11 are stable, namely the rock and soil body is saturated, recording the reading N of the pressure sensor 10 at the moment, and obtaining the buoyancy F 2 of the buoyancy test bottom plate 9 under the working condition of full water head according to the formula (3);
f 2 =n+g+f (3)
In the formula (3), F 2 is the buoyancy force born by the buoyancy test bottom plate, F is the friction force between the buoyancy test bottom plate 9 and the side wall of the steel inner cylinder 5 under different pressure water heads, G is the weight of the buoyancy test bottom plate 9, and N is the reading of the pressure sensor 10 under different pressure water heads;
According to the relation curve of the bottom water pressure value F 1 and the friction force F under different pressure water heads, the friction force F under the full water head working condition is obtained, the reading of the pressure sensor 10 under the full water head working condition is read, and the buoyancy F 2 borne by the buoyancy test bottom plate 9 under the full water head working condition is obtained;
S7: the water injection keeps the pebble layer 18 in a full water state unchanged, and drain pipe valves of the first blind ditch 4 and/or the second blind ditch 6 are/is opened according to the situation to drain water; and recording the water discharge time and the water discharge quantity of the first blind ditch 4 or the second blind ditch 6 under the working conditions of independent water discharge and combined water discharge, recording corresponding water head data and the reading N of the pressure sensor 10 when the flow is stable, and continuously obtaining the buoyancy F 2 born by the buoyancy test bottom plate 9 under the working conditions of each pressure water head according to the step S6.
The simulation test result of the invention can provide theoretical basis and technical support for the anti-floating stable design of the subway underground station structure, and can also provide reference for the anti-floating stable design of engineering structures such as municipal underground engineering, underground space and the like, thereby having important theoretical significance and engineering application value; and because of huge investment in subway engineering, the device provides a reasonable formula for calculating the buoyancy of the base water through experimental study, reduces the investment and construction period investment in anti-floating measures, and generates remarkable economic benefit.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (7)
1. The simulation test device for measuring the buoyancy of the bottom plate of the underground station is characterized by comprising a reinforced concrete test pool (1);
The reinforced concrete test pool (1) is internally filled with a clay layer (2) and a sand layer (3) from bottom to top, a pebble layer (18) is arranged at the top of the sand layer (3), a steel inner cylinder (5) is vertically arranged in the middle of the reinforced concrete test pool (1), the bottom of the steel inner cylinder (5) is arranged in the clay layer (2), and the top of the steel inner cylinder is not lower than the elevation of the top surface of the sand layer (3);
A first blind ditch (4) is arranged below the steel inner barrel (5), a steel wire mesh (7) is arranged on the top surface of the first blind ditch (4), and the bottom edge of the steel inner barrel (5) is fixed with the steel wire mesh (7); the outer side of the steel inner cylinder (5) is provided with a second blind ditch (6), and the second blind ditch (6) is arranged in the clay layer (2); the first blind ditch (4) and the second blind ditch (6) are communicated with the outside of the reinforced concrete test pool (1) through corresponding drain pipes and water level pipes;
The bottom of the steel inner cylinder (5) is connected with a buoyancy testing bottom plate (9) through a bottom plate connecting assembly (8), the joint of the steel inner cylinder and the buoyancy testing bottom plate is sealed, and the buoyancy testing bottom plate (9) can vertically and limitedly move in the bottom plate connecting assembly (8); a first steel plate strip (801) and a second steel plate strip (802) are vertically arranged at intervals on the inner side of the bottom of the steel inner barrel (5), steel rings (803) are arranged on the inner sides of the first steel plate strip (801) and the second steel plate strip (802), and the buoyancy test bottom plate (9) is fixedly arranged between the steel rings (803); a limiting pin (804) is fixed in the annular groove of the steel ring (803), and one end of the limiting pin is positioned between the first steel plate strip (801) and the second steel plate strip (802);
The bottom surface of the steel ring (803) and the bottom surface of the first steel plate strip (801) are provided with flexible water stop strips (805), and the flexible water stop strips (805) are connected with the two through a bolt assembly; meanwhile, flexible water stop strips (805) are arranged on the top surfaces of the steel ring (803) and the second steel plate strip (802), and the flexible water stop strips (805) are connected with the two steel plate strips through a bolt assembly;
Be equipped with a plurality of pressure sensor (10) and displacement sensor (11) on buoyancy test bottom plate (9), wherein pressure sensor (10) are fixed in its top, and pressure sensor (10) accessible compression set shape measurement current pressure value, steel structure support (12) bottom of vertical setting in steel inner tube (5) with pressure sensor (10) are connected, and the top is connected with top bearing structure, top bearing structure is fixed in reinforced concrete test pond (1) pool wall top surface.
2. The simulation test device for measuring the buoyancy of the bottom plate of the underground station according to claim 1, wherein the first blind ditch (4) and the second blind ditch (6) are connected with water level pipes, and the other ends of the water level pipes are communicated with corresponding water level identification plates (17) on the outer wall of the reinforced concrete test tank (1) so as to intuitively read corresponding water levels through reading.
3. The simulation test device for measuring the buoyancy of the bottom plate of the underground station according to claim 1 or 2, wherein the drain pipe connected with the first blind ditch (4) and the second blind ditch (6) is provided with an independent valve outside the reinforced concrete test pool (1).
4. The simulation test device for measuring the buoyancy of the bottom plate of the underground station according to claim 2, wherein a step is arranged outside the reinforced concrete test pool (1) so as to be convenient for reading a water level signboard (17), and a step is arranged on the steel structure support (12) so as to be convenient for test personnel to reach the bottom of the steel inner cylinder.
5. A method of constructing a simulation test apparatus for measuring the buoyancy of a floor of an underground station according to any one of claims 1 to 4, comprising the steps of:
1) Constructing a reinforced concrete test pool (1) at a test site;
2) After the concrete strength of the reinforced concrete test pool reaches the design strength, burying a clay layer (2) in the test pool by adopting a layered compaction method;
3) After the clay layer (2) is buried to the designed elevation, a first blind ditch (4) at the bottom of the steel inner cylinder is manufactured in the test pool, and a first water level pipe (13) and a first drain pipe (14) with a valve are arranged at the bottom of the blind ditch;
4) A steel wire mesh (7) is arranged on the top surface of the first blind ditch (4), and a steel inner cylinder (5) is arranged on the accurately positioned steel wire mesh;
5) After the installation of the steel inner cylinder (5) is completed, continuously filling a soil clay layer (2) between the steel inner cylinder (5) and the reinforced concrete test pool (1), arranging a second annular blind ditch (6) at a corresponding design position on the outer side of the steel inner cylinder (5), and arranging a second water level pipe (15) and a second drain pipe (16) with a valve at the bottom of the second blind ditch (6);
6) Continuously filling a clay layer (2), and filling a sand layer (3) and a pebble layer (18) above the clay layer (2);
7) After the filling of the reinforced concrete test pool (1) reaches the designed elevation, a bottom plate connecting assembly (8) and a buoyancy testing bottom plate (9) are arranged on the inner wall of the steel inner cylinder (5), a plurality of displacement sensors (11) are arranged at the bottom of the buoyancy testing bottom plate (9), and a plurality of pressure sensors (10) are arranged at the top;
8) And hoisting a steel structure bracket (12) in the steel inner cylinder, and respectively connecting the top and the bottom of the steel structure bracket with the top supporting structure and the pressure sensor (10).
6. The construction method of the simulation test device for measuring the buoyancy of the bottom plate of the underground station according to claim 5, wherein after the pressure sensor (10) and the displacement sensor (11) are installed, cables of the sensors are connected to corresponding data acquisition boxes outside the reinforced concrete test tank (1).
7. A test method of a simulation test apparatus for measuring the buoyancy of a floor of an underground station according to any one of claims 1 to 4, comprising the steps of:
s1: backfilling the rock-soil body retrieved on site to the bottom of the first blind ditch (4) according to the geological condition on site;
s2: injecting water step by step into the reinforced concrete test pool (1), and obtaining each pressure water head according to the stable reading of the first water level pipe (13) And calculating the bottom water pressure values under different pressure heads according to the formula (1):
(1)
In the formula (1), F is the bottom water pressure value under different pressure heads,For the weight of the water to be high,The pressure water head is a pressure water head, A is the area of a buoyancy test bottom plate;
s3: recording readings N of pressure sensors (10) under different pressure heads, respectively obtaining friction forces F between a buoyancy test bottom plate (9) and the side wall of the steel inner cylinder (5) under different pressure heads through a formula (2), and drawing a relation curve of bottom water pressure values F 1 and the friction forces F under different pressure heads;
(2)
In the formula (2), F 1 is the bottom water pressure value under different pressure heads, G is the weight of the buoyancy test bottom plate (9), and N is the reading of the pressure sensor (10) under different pressure heads;
s4: draining water in the reinforced concrete test pool (1), and continuously backfilling the rock and soil retrieved in the site to the required elevation of the reinforced concrete test pool (1) by referring to the geological condition of the site and compacting;
S5: injecting water into the pebble layer (18) and keeping the pebble layer in a water-filled state;
S6: when the readings of the pressure sensor (10) and the displacement sensor (11) are stable, namely the rock and soil body is saturated, the friction force F under the working condition of full water head is obtained according to the step S3, the reading N of the pressure sensor (10) at the moment is recorded, and the buoyancy F 2 born by the buoyancy test bottom plate (9) under the working condition of full water head is obtained according to the formula (3);
(3)
In the formula (3), F 2 is the buoyancy force born by the buoyancy force testing bottom plate, F is the friction force between the buoyancy force testing bottom plate and the side wall of the steel inner cylinder under different pressure water heads, G is the weight of the buoyancy force testing bottom plate, and N is the reading of the pressure sensor under different pressure water heads;
S7: the water injection keeps the water filling state of the pebble layer (18) unchanged, and drain pipe valves of the first blind ditch (4) and/or the second blind ditch (6) are/is opened according to the situation to drain water; and recording the water discharge time and the water discharge quantity of the two blind ditches under the working conditions of independent water discharge and combined water discharge, and continuously obtaining the buoyancy F 2 born by the buoyancy test bottom plate (9) under the working conditions of each pressure water head according to the step S6.
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| CN202210988005.4A CN115389182B (en) | 2022-08-17 | Simulation test device for measuring buoyancy of bottom plate of underground station, installation and test method |
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| CN110987507A (en) * | 2019-12-30 | 2020-04-10 | 北京城建勘测设计研究院有限责任公司 | Buoyancy model test device |
| CN114740179A (en) * | 2022-03-30 | 2022-07-12 | 东华理工大学 | Anti design model test case that floats of underground building structure |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110987507A (en) * | 2019-12-30 | 2020-04-10 | 北京城建勘测设计研究院有限责任公司 | Buoyancy model test device |
| CN114740179A (en) * | 2022-03-30 | 2022-07-12 | 东华理工大学 | Anti design model test case that floats of underground building structure |
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