CN113358484A - Test system and method for simulating dam body soil deformation in water level lifting process - Google Patents
Test system and method for simulating dam body soil deformation in water level lifting process Download PDFInfo
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Abstract
The invention discloses a test system and a method for simulating dam body soil deformation in a water level lifting process, which mainly comprise a lever loading device, a test system and a high-precision hydraulic device; the test system is arranged on the lever loading device, and a high-precision water pressure device is arranged on one side of the test system; the lever loading device consists of a bearing platform, a base, a balance weight, a lever, a weight, a stand column and a slide rail; the test system comprises a dial indicator, a copper transmission cover with holes, a copper guide ring, a permeable stone, a steel compression cutting ring and a pressure chamber; the high-precision hydraulic device consists of a high-precision water pressure meter and a hydraulic testing machine. By adopting the dam body soil water level lifting process deformation simulation test system disclosed by the invention, the accurate combination of loads at different depths and any water pressure can be realized by independently applying overburden pressure and pore water pressure, and the real properties and the whole process deformation of dam body soil at different depths under the action of water level lifting are simulated.
Description
Technical Field
The invention relates to the field of water conservancy science research, in particular to a test system and a test method for simulating dam body soil deformation in a water level lifting process.
Background
The reservoir dam in China has 9.8 thousands of seats, more than 90% of which are earth-rock dams, and are mainly built in the last 50-70 century, thereby playing great social benefits, economic benefits and ecological benefits in the aspects of flood control, irrigation, water supply, power generation and the like. Due to special historical periods and economic and technical conditions, the dams have inherent defects, the phenomenon that the dams are operated beyond the designed service life is common, and the risk problem of the earth-rock dams is increasingly prominent along with the increase of the service life. Therefore, the reinforcement and treatment of the sick soil and rock dam become a long and difficult task for the construction and management of the hydraulic engineering in China.
In recent years, the problem of cracking of the top of the dam is found in the safety certification work after reinforcement of a considerable number of seepage-proofing wall reinforced earth-rock dams after the dam is operated for years. Due to the insufficient knowledge of the deformation rule and the internal mechanism of the reinforced dam body, the key problems related to the safety of the dam, such as the deformation stability trend of the dam body, the crack hazard degree and the like, are lack of scientific judgment. At present, deformation analysis of a reinforced dam body becomes a key technical bottleneck for promoting safety evaluation of a dam structure.
The traditional soil deformation test method (such as a triaxial compression test, a consolidation test and the like) is mainly suitable for deformation analysis of a newly-built earth-rock dam in a construction period or at the initial stage of water storage operation, and factors such as self-weight load, water level load, humidification and consolidation of dam body soil at the moment have obvious effects. For old dams which have been operated for decades, dam body soil deformation caused by repeated rise and fall of reservoir water levels becomes a main contributing factor of the overall deformation of the dam in the operation period, and at the moment, the traditional soil deformation test method cannot be met. Therefore, accurate simulation of dam body soil deformation under the reservoir water level lifting action is the key to solve the difficult problem of dam body deformation reinforcement, and the corresponding test system and method are urgent and necessary.
The dam body soil stress is mainly divided into overburden soil pressure and pore water pressure in the vertical direction. This experiment provides stable axial pressure by lever loading device, lever loading device is by the cushion cap, a pedestal, the counter weight, lever and weight are constituteed, through lever pressurization principle, the mode that increases weight provides axial pressure to the dowel steel, axial pressure passes through the dowel steel and applys on the test piece in the pressure chamber, dowel steel one end is at the porose pressure transmission lid top of copper, the other end extends out the pressure chamber, the junction adopts the isolated infiltration of rubber stagnant water, the dowel steel, porose pressure transmission lid of copper, the combination of copper guide ring transmits to the test piece, this axle pressure application system can simulate soil body dead weight stress betterly. This experiment is by high accuracy water pressure equipment device to the pressure chamber water injection, and high accuracy water pressure equipment device comprises high accuracy water pressure table, hydrostatic testing machine, reads the water pressure value through the high accuracy water pressure table, adopts hydrostatic testing machine regulation water pressure value to target value, and then realizes the accurate regulation and control of water pressure value. Pore water pressure permeates the permeable stone and the porous copper pressure transmission cover to be stably transmitted to the test piece. The stable axial pressure can simulate the overlying soil pressure of dam body soil to carry out consolidation, and the pore water pressure of different depths can be realized by controlling the water pressure in the pressure chamber.
In a general strength test method (lateral load is realized through confining pressure, such as triaxial compression), a soil sample test piece is fixed by a rubber sleeve, lateral deformation of a soil body is not limited, the soil body can simultaneously generate vertical deformation and lateral deformation, the soil body generates deformation damage along with increase of main stress difference, and the shear failure effect of the soil body is mainly researched. According to the invention, a steel compression cutting ring is adopted to realize lateral restraint of a soil sample, a vertical load is independently applied, only vertical deformation is generated, lateral deformation and shearing deformation are not generated, and the real stress state of dam body soil is simulated;
the soil body test piece of the traditional triaxial test equipment is not contacted with water constantly, but is subjected to confining pressure by applying a water pressure mode to the rubber sleeve, and the deformation process of the soil body test piece under the lateral constraint condition under the action of different pore water pressures cannot be simulated. The copper transmission cover and the copper guide ring have the functions of transmitting axial pressure and performing punching treatment on the copper transmission cover on the basis, and the purpose of fully contacting water with a soil test piece so as to better transmit pore water pressure to the interior of a soil body.
Disclosure of Invention
The invention aims to simulate a test of deformation of dam body soil in a water level lifting process, maintain axial pressure to limit lateral deformation of a sample, and simulate vertical deformation of a certain point of dam body soil under the action of different stable pore water pressures; the soil deformation test method under the condition of variable pore water pressure for realizing lateral restraint by utilizing the steel compression cutting ring is a test system and a method for simulating dam body soil deformation in the water level lifting process.
In order to achieve the purpose, the invention provides a test system for simulating dam body soil deformation in a water level lifting process, which mainly comprises a lever loading device, a test system and a high-precision hydraulic device; the method is characterized in that: the test system is arranged on the lever loading device, and a high-precision water pressure device is arranged on one side of the test system; the test system comprises a dial indicator, a copper transmission cover with holes, a copper guide ring, a permeable stone, a steel compression cutting ring and a pressure chamber; the external amesdial that has of pressure chamber upper end, the built-in part of pressure chamber from the top down does in proper order: porose copper passes gland, copper guide ring, top permeable stone, steel compression cutting ring and bottom permeable stone, and porose copper passes gland bottom and copper guide ring top size coincide to be connected promptly, and copper guide ring bottom and steel compression cutting ring top size coincide to be connected, and the top permeable stone is placed in the copper guide intra-annular, and steel compression cutting ring upper portion, bottom permeable stone are placed in steel compression cutting ring lower part.
Furthermore, the lever loading device consists of a bearing platform, a base, a balance weight, a lever, a weight and a stand column; the bearing platform and the base are fixed through the upright posts by bolts or welding, the lever is connected with the upright posts in a rotatable joint mode, a balance weight is arranged at one end of the left side of the lever, and a weight is arranged at one end of the right side of the lever; the high-precision water pressure device consists of a high-precision water pressure meter and a water pressure testing machine, and the high-precision water pressure meter is arranged on one side of the water pressure testing machine.
Furthermore, the test system also comprises a dowel bar, a piston type bearing, a rubber water stop, an exhaust valve and a slide rail; the testing system is arranged at the upper end of a base on the lever loading device, a hydrostatic testing machine on the high-precision hydrostatic device is connected with the pressure chamber, and the high-precision hydrostatic meter is arranged on one side of the pressure chamber; the dowel bar is connected with a lever loading device as follows: the connecting part of the lever and the dowel bar is connected by adopting a sliding rail, the sliding rail ensures that the dowel bar only moves axially, and the upper end of the sliding rail is fixed on the bearing platform by adopting a bolt or welding; the dowel bar is connected with a test system as follows: the dowel bar is connected with the pressure chamber through a piston type bearing, one end of the dowel bar is arranged at the top end of the perforated copper dowel cover, the other end of the dowel bar extends out of the pressure chamber, the joint is sealed by rubber to prevent water seepage, and the exhaust valve is arranged on the other side of the top end of the pressure chamber.
Furthermore, vertical loads are independently applied through the lever loading device, the axial pressure application system can better simulate the self-weight stress of the soil body, the simulation of the pressure of the soil bodies at different depths is realized, and meanwhile, the vertical loads in the whole test process are kept constant; the piston type bearing is adopted to ensure smooth force transmission, and the weight of the weight is increased by providing axial pressure for the force transmission rod through a lever pressurization principle, so that the axial load is transmitted to the porous copper pressure transmission cover in the pressure chamber and finally acts on a test piece, and the principle of the axial pressure transmission cover is similar to that of a consolidation apparatus.
Further, the high-precision hydraulic device is adopted, and comprises a high-precision hydraulic meter and a hydraulic testing machine, stable hydraulic pressure is injected into the pressure chamber by the high-precision hydraulic device, the water pressure transmits the permeable stone and the porous copper pressure transmission cover to transmit stable pore water pressure to the test piece, so that simulation of the pore water pressure in the soil sample is realized, meanwhile, balance of the upper and lower water pressures of the pressure cover is realized through the permeable stone and the porous pressure cover, and the influence of the water pressure in the pressure chamber on vertical load is counteracted; and reading the water pressure value through a high-precision water pressure meter, and adjusting the water pressure value to a target value by using a hydrostatic testing machine so as to realize accurate regulation and control of the water pressure value.
Furthermore, the pressure chamber is made of organic glass, indoor test conditions can be clearly observed, the strength and the rigidity of the pressure chamber can guarantee that stable water pressure is not deformed and damaged after injection, a hole copper-made pressure transmission cover, a copper guide ring and permeable stones are arranged in the pressure chamber, the pressure of pore water in the pressure chamber can smoothly enter a soil body test piece, a sample is prepared by a steel compression cutting ring, lateral deformation is limited by the steel compression cutting ring in the test process, and the deformation state of actual dam body soil can be well simulated. The permeable stones are respectively arranged at two positions, one permeable stone is arranged at the bottom of the pressure chamber, namely the lower part of the steel compression cutting ring, the diameter of the permeable stone is slightly larger than the outer diameter of the steel compression cutting ring by 10-20mm, the other permeable stone is arranged at the upper part of the steel compression cutting ring, the diameter of the permeable stone is slightly smaller than the steel compression cutting ring by 2-5mm, the copper guide ring is provided with a caulking joint which can be fixed above the steel compression cutting ring, and the diameter of the copper pressure transmission cover with holes is equal to that of the permeable stone on the steel compression cutting ring. Therefore, the pore water pressure can be stably transferred to the soil test piece, and the smooth transfer of water in the soil test piece is realized.
Furthermore, the diameter of the test sample can be customized according to actual needs, and the sizes of the steel compression cutting ring, the copper guide ring, the copper perforated transmission cover and the permeable stone can be customized. Compare the rubber sleeve of traditional triaxial, this test system's steel compression cutting ring system appearance fine control test piece volume and degree of consistency, retrained the lateral deformation of soil body test piece, can fine control experimental variable, satisfy the plane and meet an emergency problem hypothesis, more accord with the actual stress state of dam body soil. The arrangement of porose copper biography gland, permeable stone and equipment gap can let the aperture water pressure get into the test piece well, compares traditional triaxial closed structure, and porose structure can simulate the influence of aperture water pressure to soil sample test piece better, also more accords with the actual condition of reservoir water level lift process soil body.
As a further technical scheme, the test method for simulating the deformation of the dam body soil in the water level lifting process comprises the following steps:
the first step is the sample preparation process of the test piece:
(1) processing and manufacturing a dam body soil sample according to the requirements of meeting the water content and density of the test;
(2) calculating the wet density of the soil according to the density and the water content, then weighing the corresponding weight of the container volume, and uniformly pressing the soil into a steel compression cutting ring;
(3) after the compression is finished, the compressed soil sample is not required to be taken out, and the steel compression cutting ring of the compressed soil sample is directly used as a sample container;
the second step is a test process for simulating deformation of the dam body soil water level lifting process:
(1) the bearing platform and the base are fixed through the upright posts in a bolt or welding mode by adopting an assembled structure, the lever is connected with the upright posts in a rotatable joint mode, the lever can rotate along with the joints, the normal operation of the lever is ensured, the joints of the lever and the force transmission rod are connected through the sliding rails, the sliding rails need to ensure that the force transmission rod only moves axially, the upper ends of the sliding rails are fixed on the bearing platform in a bolt or welding mode, and axial pressure is provided for the force transmission rod in a mode of increasing the weight of the weight;
(2) placing a bottom porous stone in the center of the bottom of the pressure chamber, placing the manufactured steel compression cutting ring and the sample therein on the porous stone, placing a layer of filter paper above and below the sample in the steel compression cutting ring, and fixing the top porous stone and the porous copper transmission cover on the upper part of the steel compression cutting ring to combine the two;
(3) installing a pressure chamber for uniaxial prepressing, so that the dowel bar is embedded into the perforated copper pressure transmission cover until the dowel bar is contacted to change the reading of the dial indicator, namely indicating that the axial pressure is successfully applied;
(4) screwing down the fixing bolts of the pressure chamber and the chassis to fix the pressure chamber on a horizontal plane;
(5) when the test is started, the pore water pressure is naturally and slowly immersed from the bottom, the pore pressure is 0 at the moment, the pore water flows out to an upper exhaust valve, and bubbles in the pressure chamber are removed, so that the whole pressure chamber is filled with water;
(6) converting the axial pressure to be applied according to the overburden soil pressure required by the test, and applying the axial pressure to the test piece to solidify the test piece;
(7) under the condition of keeping the axial pressure unchanged, a high-precision water pressure device provides and adjusts water pressure for the pressure chamber, and the size of the high-precision water pressure device is adjusted according to the reservoir water level lifting condition;
(8) observing the compression deformation on the dial indicator, and observing and recording the deformation reading of the sample after maintaining the actual deformation stable condition required by the test;
(9) according to different reservoir water levels, adjusting the water pressure, keeping the axial pressure unchanged, and observing and recording the deformation of the sample;
(10) and (5) repeating the steps (8) and (9) to observe and record the deformation of the sample until the test is finished.
Furthermore, the innovation of the sample preparation process of the first test piece is as follows: different from a common triaxial test, the test sample preparation does not adopt a compaction instrument, but adopts a compression cutting ring to prepare the sample, so that compared with the prior art, the volume and the density of the sample can be strictly controlled, and the consistency of the density condition of the soil sample in each test can be ensured. And the compression cutting ring is also used as a test container, the sample preparation is finished without taking out, and the direct test is carried out, so that the influence of the peeling deformation and the like of the soil body which is taken out and then installed is reduced. Compared with the rubber sleeve fixation of the original triaxial test, the test for simulating the deformation of the dam body soil water level lifting process in the second step adopts an assembled structure (see attached figure 1), and the assembled structure can meet the test requirement and can transmit pressure more intuitively. The axial pressure transmission way is as follows: axial pressure is provided by the lever loading device and then is transmitted to a sample through the force transmission rod, the pressure transmission cover, the copper guide ring and the permeable stone; the pore pressure transmission way is as follows: the high-precision water pressure device is used for providing water pressure into the pressure chamber and consists of a high-precision water pressure meter and a water pressure testing machine, the water pressure value is read through the high-precision water pressure meter, the water pressure value is adjusted to a target value by the water pressure testing machine, then the accurate regulation and control of the water pressure value are realized, and the pore water pressure is stably transmitted to a sample through the permeable stone and the porous pressure transmission cover.
The invention has the following beneficial effects: (1) the copper guide ring, the copper porous pressure transmission cover and the permeable stone are placed on the test piece, the test piece is treated as above, and good conditions and space are provided for the test piece to better bear axial pressure and pore water pressure. The steel compression cutting ring is adopted for sample loading and lateral deformation control, the volume of the test piece can be strictly controlled during sample preparation by the steel compression cutting ring, so that the test piece is kept consistent, the steel compression cutting ring has higher rigidity, other deformation which does not belong to the test requirement cannot be generated on the test piece during the test, and the whole combination can well simulate the stress deformation of dam body soil during the water level lifting process; (2) the copper guide ring is in a ring shape and is provided with an embedding opening matched with the upper part of the steel compression cutting ring, so that the copper perforated pressure transmission cover is fixed and centered. The copper perforated transmission cover is in a pot cover shape, the upper part of the copper perforated transmission cover can be tightly matched with the transmission rod, and the size of the lower part of the copper perforated transmission cover is consistent with that of a test piece, so that the pressure in the transmission rod is uniformly distributed in the test piece. (3) The permeable stone for transmitting pressure and water has better strength and good water permeability, is designed into a cylindrical shape, and is used for transmitting and bearing axial pressure and simultaneously permeating water so as to fulfill the aim of applying pore water pressure. (4) The copper pressure transmission cover is punched, a water permeable channel can be increased, the interference of the water pressure difference between the upper water and the lower water of the pressure transmission cover on the test load of the soil sample is avoided, and meanwhile, the pore water pressure is transmitted to the sample more stably. (5) The method is simple and convenient to operate in the concrete test process, and can complete the deformation test for simulating the dam body soil water level lifting process only by simply preparing and assembling the test piece. (6) By adopting the dam body soil water level lifting process simulation deformation test system disclosed by the invention, the obtained data is accurate and reliable. In the test, the accurate combination of loads at different depths and any water pressure is realized by independently applying overburden soil pressure and pore water pressure, and the real characters and the whole-process deformation of dam body soil at different depths under the action of water level elevation are simulated.
Drawings
FIG. 1 is a schematic diagram of a test for simulating deformation of dam body soil during water level elevation;
FIG. 2 is a view showing the structure of a pressure chamber
FIG. 3 is a front view of a vented copper pressure transfer cover of the present invention;
FIG. 4 is a top view of a perforated copper pressure transfer cover of the present invention;
FIG. 5 is a front view of a copper guide ring of the present invention;
FIG. 6 is a top view (from top to bottom) of the copper guide ring of the present invention;
fig. 7 is a top view (from bottom to top) of the copper guide ring of the present invention.
FIG. 8 is a front view of the steel compression ring cutter of the present invention.
FIG. 9 is a left side view of the steel compression ring cutter of the present invention.
In the figure, 1-bearing platform, 2-base, 3-balance weight, 4-lever, 5-dowel bar, 6-weight, 7-dial indicator, 8-piston type bearing, 9-rubber water stop, 10-exhaust valve, 11-copper pressure transmission cover with holes, 12-copper guide ring, 13-top permeable stone, 14-bottom permeable stone, 15-soil sample, 16-steel compression cutting ring, 17-fixing bolt, 18-high precision water pressure meter, 19-hydrostatic testing machine, 20-pressure chamber, 21-upright post and 22-slide rail.
Detailed Description
As introduced in the background art, the influence of repeated reservoir water level elevation on the deformation of dam body soil becomes a key scientific problem which needs to be solved urgently in the safety evaluation of the structure of the reinforced earth-rock dam, and a simulation test is an effective means. The method comprises the following specific steps: the stress of dam body soil in the reservoir is mainly divided into overlying soil pressure in the vertical direction and pore water pressure in all directions, axial pressure and pore water pressure are stably applied to a soil body test piece through a lever loading device and a high-precision water pressure device, the stable axial pressure can simulate the overlying soil pressure on the dam body to be consolidated, and the water pressure of different depths can be realized by controlling the pore water pressure.
In order to achieve the test, the application provides a deformation test system and method for simulating the dam body soil water level lifting process. In this embodiment, as shown in fig. 1, a test system for simulating deformation of dam body soil during water level elevation process includes: the device comprises a bearing platform 1, a base 2, a balance weight 3, a lever 4, a force transmission rod 5, a weight 6, a dial indicator 7, a piston type bearing 8, a rubber water stop 9, an exhaust valve 10, a copper pressure transmission cover 11 with holes, a copper guide ring 12, a top permeable stone 13, a bottom permeable stone 14, a soil body sample 15, a steel compression cutting ring 16, a fixing bolt 17, a high-precision water pressure meter 18, a hydrostatic testing machine 19, a pressure chamber-20, an upright column-21 and a slide rail-22.
The joint of the top of the copper pressure transmission cover 11 with holes and the dowel bar 5 is a hemispherical concave surface which is matched with the hemispherical end of the dowel bar 5; the bottom of the holed copper transmission cover 11 is matched with the top of the copper guide ring 12 in size, and the bottom of the copper guide ring 12 is matched with the top of the steel compression cutting ring 16 in size. The top permeable stone 13 is placed in the copper guide ring 12, the upper part of the steel compression cutting ring 16 is placed in the copper guide ring 12, and the bottom permeable stone 14 is placed in the lower part of the steel compression cutting ring 16. The dowel bar 5, the copper dowel cover 11 with the hole and the copper guide ring 12 are on the same central line, so that the shaft pressure can be well transferred from the dowel bar 5 to the test piece 15. The copper guide ring 12 can assemble the copper perforated transmission cover 11, the top permeable stone 7 and the steel compression cutting ring 16 together, so that the soil body test piece 15 can bear stable and accurate axial pressure and pore water pressure in the test.
The concrete manufacturing method of the soil sample test piece comprises the following steps:
(1) processing and manufacturing a dam body soil sample according to the requirements of meeting the water content, density and the like of the test;
(2) and calculating the wet density of the soil according to the density and the water content, then weighing the weight corresponding to the volume of the container, and uniformly pressing the soil into the steel compression cutting ring 16.
(3) After the compression is completed, the compressed soil sample is not required to be taken out, and the steel compression cutting ring 16 of the compressed soil sample 15 is directly used as a sample container.
(4) And (3) flattening the redundant soil on two sides of the steel compression cutting ring 16 provided with the soil body test piece by using a knife, completing sample preparation, and assembling an instrument for preparation test.
The dam body soil deformation test method in the water level lifting process by using the device has the following specific operations:
(1) the lever loading device is composed of a bearing platform 1, a base 2, a balance weight 3, a lever 4, a column 21, a slide rail 22 and a weight 6. The assembling method specifically comprises the steps that the bearing platform 1 and the base 2 are fixed through the upright post 21 through bolts or welding, the lever 4 is connected with the upright post 21 in a rotatable joint mode, the lever 4 can rotate along with the joint, normal operation of the lever 4 is guaranteed, the joint of the lever 4 and the force transmission rod 5 is connected through the sliding rail 22, the sliding rail 22 needs to guarantee that the force transmission rod 5 only moves axially, and the upper end of the sliding rail 22 is fixed on the bearing platform 1 through bolts or welding, as shown in the attached drawing 1. Axial pressure is provided to the dowel 5 by increasing the weight of the weight 6.
(2) The bottom permeable stone 14 is placed in the center of the bottom of the pressure chamber 20, the manufactured steel compression cutting ring 16 and the sample inside the steel compression cutting ring 16 are placed on the bottom permeable stone 14, a layer of filter paper is placed above and below the sample inside the steel compression cutting ring 16, and then the top permeable stone 13, the copper guide ring 12 and the porous copper transmission cover 11 are fixed on the upper portion of the steel compression cutting ring 16 to be combined.
(2) A pressure chamber 20 is arranged for uniaxial prepressing, so that the dowel bar 5 is embedded into the holed copper transmission cover 11 until the contact occurs to change the reading of the dial indicator 7, namely the successful application of the axial pressure is indicated;
(3) screwing the pressure chamber 20 and the fixing bolt 17 of the chassis, so that the pressure chamber 20 is fixed on a horizontal plane;
(4) when the test is started, the pore water pressure naturally and slowly immerses from the bottom (at the moment, the pore pressure is 0), flows out to the upper exhaust valve 10, and removes air bubbles in the pressure chamber 20, so that the whole pressure chamber 20 is filled with water;
(5) the axial pressure to be applied is calculated according to the overburden pressure required by the test, and is applied to the test piece 15 to consolidate the test piece 15.
(6) Under the condition of keeping the axial pressure unchanged, a high-precision water pressure device provides pore water pressure for the pressure chamber 20, and the high-precision water pressure device consists of a high-precision water pressure gauge 18 and a water pressure testing machine 19. Adopt hydrostatic test machine 19 to adjust the water pressure value to experimental required target value, to water injection in pressure chamber 20, read the water pressure value through high accuracy water pressure gauge 18, and then realize the accurate regulation and control of water pressure value, like figure 1, pore water pressure permeates permeable stone 7, porose pressure transmission lid 11 and stably transmits to the sample in.
(7) The amount of compression set on the dial gauge 7 is observed and the sample deformation reading is observed and recorded after the actual deformation stabilizing conditions required for the test are maintained.
(8) And (4) according to different reservoir water levels, adjusting the water pressure, keeping the axial pressure unchanged, and observing and recording the deformation of the sample.
(9) And (5) repeating the steps (7) and (8) to observe and record the deformation of the sample until the test is finished.
In the stress process of the test piece, in order to control the lateral deformation of the soil test piece 15, a steel compression cutting ring 16 is adopted for sample loading and lateral deformation control, and the volume of the test piece can be strictly controlled to keep the test piece consistent when the sample is prepared by the steel compression cutting ring 16. And the steel compression cutting ring 16 has higher rigidity, so that other deformation which does not belong to the test requirement can not be generated on the test piece during the test. The whole combination can well simulate the stress deformation of dam body soil in the water level lifting process.
The permeable stone 7 for transmitting pressure and water is a mixed material of cement, water, permeable concrete reinforcing agent mixed with high-quality aggregates of same grain size or discontinuous gradation, and has a certain porosity, and it has better strength and excellent water permeability. The permeable stone is designed to be cylindrical in shape, so as to transmit and bear axial pressure and simultaneously permeate water, thereby exerting pore water pressure.
The steel compression cutting ring 16 is a test instrument for taking undisturbed soil (undisturbed) test samples and performing tests such as volume weight, compression, shearing, permeation and the like.
The copper guide ring 12 and the holed copper pressure transmission cover 11 for transmitting pressure have good rigidity and strength, and the copper guide ring 12 is in a circular ring shape and is provided with an embedded opening matched with the upper part of the steel compression cutting ring 16 so as to fix the holed copper pressure transmission cover 11 and ensure the centering. The joint of the top of the holed copper pressure transmission cover 11 and the dowel bar 5 is a hemispherical concave surface which is matched with a hemispherical end of the dowel bar 5, so that the axial pressure is uniformly transmitted to the test piece 15.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (4)
1. A test system for simulating dam body soil deformation in a water level lifting process mainly comprises a lever loading device, a test system and a high-precision hydraulic device; the method is characterized in that: the test system is arranged on the lever loading device, and a high-precision water pressure device is arranged on one side of the test system; the test system comprises a dial indicator, a copper transmission cover with holes, a copper guide ring, a permeable stone, a steel compression cutting ring and a pressure chamber; the external amesdial that has of pressure chamber upper end, the built-in part of pressure chamber from the top down does in proper order: porose copper passes gland, copper guide ring, top permeable stone, steel compression cutting ring and bottom permeable stone, and porose copper passes gland bottom and copper guide ring top size coincide to be connected promptly, and copper guide ring bottom and steel compression cutting ring top size coincide to be connected, and the top permeable stone is placed in the copper guide intra-annular, and steel compression cutting ring upper portion, bottom permeable stone are placed in steel compression cutting ring lower part.
2. The test system for simulating dam body soil deformation in the water level lifting process according to claim 1, wherein: the lever loading device consists of a bearing platform, a base, a balance weight, a lever, a weight and a stand column; the bearing platform and the base are fixed through the upright posts by bolts or welding, the lever is connected with the upright posts in a rotatable joint mode, a balance weight is arranged at one end of the left side of the lever, and a weight is arranged at one end of the right side of the lever; the high-precision water pressure device consists of a high-precision water pressure meter and a water pressure testing machine, and the high-precision water pressure meter is arranged on one side of the water pressure testing machine.
3. The test system for simulating dam body soil deformation in the water level lifting process according to claim 1, wherein: the test system also comprises a dowel bar, a piston type bearing, a rubber water stop, an exhaust valve and a slide rail; the testing system is arranged at the upper end of a base on the lever loading device, a hydrostatic testing machine on the high-precision hydrostatic device is connected with the pressure chamber, and the high-precision water pressure meter is arranged at the joint of the pressure chamber and the hydrostatic testing machine; the dowel bar is connected with a lever loading device as follows: the connecting part of the lever and the dowel bar is connected by adopting a sliding rail, the sliding rail ensures that the dowel bar only moves axially, and the upper end of the sliding rail is fixed on the bearing platform by adopting a bolt or welding; the dowel bar is connected with a test system as follows: the dowel bar is connected with the pressure chamber through a piston type bearing, one end of the dowel bar is arranged at the top end of the perforated copper dowel cover, the other end of the dowel bar extends out of the pressure chamber, the joint is sealed by rubber to prevent water seepage, and the exhaust valve is arranged on the other side of the top end of the pressure chamber.
4. A method of the test system for simulating dam soil deformation during water level elevation according to claim 1, comprising the steps of:
the first step is the sample preparation process of the test piece:
(1) processing and manufacturing a dam body soil sample according to the requirements of meeting the water content and density of the test;
(2) calculating the wet density of the soil according to the density and the water content, then weighing the corresponding weight of the container volume, and uniformly pressing the soil into a steel compression cutting ring;
(3) after the compression is finished, the compressed soil sample is not required to be taken out, and the steel compression cutting ring of the compressed soil sample is directly used as a sample container;
the second step is a test process for simulating deformation of the dam body soil water level lifting process;
(1) the bearing platform and the base are fixed through the upright posts in a bolt or welding mode by adopting an assembled structure, the lever is connected with the upright posts in a rotatable joint mode, the lever can rotate along with the joints, the normal operation of the lever is ensured, the joints of the lever and the force transmission rod are connected through the sliding rails, the sliding rails need to ensure that the force transmission rod only moves axially, the upper ends of the sliding rails are fixed on the bearing platform in a bolt or welding mode, and axial pressure is provided for the force transmission rod in a mode of increasing the weight of the weight;
(2) placing a bottom porous stone in the center of the bottom of the pressure chamber, placing the manufactured steel compression cutting ring and the sample therein on the porous stone, placing a layer of filter paper above and below the sample in the steel compression cutting ring, and fixing the top porous stone and the porous copper transmission cover on the upper part of the steel compression cutting ring to combine the two;
(3) installing a pressure chamber for uniaxial prepressing, so that the dowel bar is embedded into the perforated copper pressure transmission cover until the dowel bar is contacted to change the reading of the dial indicator, namely indicating that the axial pressure is successfully applied;
(4) screwing down the fixing bolts of the pressure chamber and the chassis to fix the pressure chamber on a horizontal plane;
(5) when the test is started, the pore water pressure is naturally and slowly immersed from the bottom, the pore pressure is 0 at the moment, the pore water flows out to an upper exhaust valve, and bubbles in the pressure chamber are removed, so that the whole pressure chamber is filled with water;
(6) converting the axial pressure to be applied according to the overburden soil pressure required by the test, and applying the axial pressure to the test piece to solidify the test piece;
(7) under the condition of keeping the axial pressure unchanged, a high-precision water pressure device provides and adjusts water pressure for the pressure chamber, and the size of the high-precision water pressure device is adjusted according to the reservoir water level lifting condition;
(8) observing the compression deformation on the dial indicator, and observing and recording the deformation reading of the sample after maintaining the actual deformation stable condition required by the test;
(9) according to different reservoir water levels, adjusting the water pressure, keeping the axial pressure unchanged, and observing and recording the deformation of the sample;
(10) and (5) repeating the steps (8) and (9) to observe and record the deformation of the sample until the test is finished.
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