CN107436140B - Settling column tester combining vacuum preloading and surcharge preloading and testing method - Google Patents
Settling column tester combining vacuum preloading and surcharge preloading and testing method Download PDFInfo
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- CN107436140B CN107436140B CN201710603195.2A CN201710603195A CN107436140B CN 107436140 B CN107436140 B CN 107436140B CN 201710603195 A CN201710603195 A CN 201710603195A CN 107436140 B CN107436140 B CN 107436140B
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Abstract
The invention relates to the field of foundation treatment research, and aims to provide a settlement column tester combining vacuum preloading and surcharge preloading and a testing method. A partition steel plate is arranged in the settling column and is connected with the displacement sensor through a hollow rigid sleeve, a drainage plate is sleeved in the rigid sleeve, and the lower part of the drainage plate is buried in a soil sample. A cover plate is arranged at the top of the settling column, and a water bag is arranged in the space between the settling column and the partition steel plate; the side wall of the settling column and the rigid sleeve are respectively provided with a vacuum tube and connected to a vacuum pump; the bottom and the side wall of the settling column are provided with a plurality of pore pressure sensors; and the pore pressure sensor and the displacement sensor are connected to a data acquisition system through signal lines. The invention has simple structure and is easy to operate; the pile loading value can be simply and conveniently changed through water pressure control, and the change of the pore pressures at different radial positions in the consolidation process can be effectively obtained; the data can be automatically recorded, the hands required by the experiment are reduced, and the errors generated during manual reading are reduced; the model material and the filling can be repeatedly used, and waste and pollution can not be caused.
Description
Technical Field
The invention relates to the field of foundation treatment research, in particular to a settlement column tester combining vacuum preloading and surcharge preloading and a testing method.
Background
With the high-speed development of economic society in China, the urbanization process and construction industry are continuously promoted, and a large number of large buildings and structures such as highways, high-speed railways, high-rise buildings, airports and the like are built in coastal developed areas such as the Long triangular and the Pearl triangular. For geographical history reasons, these regions are mostly distributed with deep and soft clay with high natural water content, large natural pore ratio, high compressibility and low permeability, and such soil layers have natural disadvantages when used as foundations. Because the strength is low, the bearing capacity and stability of the foundation are often insufficient, and instability damage is easily caused; due to the high compressibility and low permeability, the building can be caused to have considerable settlement or uneven settlement, and the long duration of the settlement process can affect the normal use of the building and even endanger the safety of the building. Therefore, soft clay foundations generally need to be treated.
The shaft drainage consolidation method is widely applied to a plurality of soft foundation treatment methods, and is characterized in that vertical drainage wells (comprising sand wells, bagged sand wells, plastic drainage belts and the like) are arranged in a foundation, and a certain loading mode (usually, the self weight of an upper structure, preloading or vacuum preloading) is combined for graded loading, so that pore water in soft clay is gradually discharged, the soil consolidation speed is accelerated, the consolidation time is shortened, and the purposes of quickly enhancing the strength of foundation soil, improving the bearing capacity of the foundation, reducing the total settlement and uneven settlement of the foundation and ensuring the stability and safety of the upper structure are finally realized. The loading mode of combining the surcharge preloading and the vacuum preloading is widely used in engineering practice. Theoretical research shows that the speed of treating the soft clay foundation by pure vacuum preloading is superior to that of singly using surcharge preloading; under the condition that the equivalent total pressure is equal, the ratio of the vacuum prepressing to the surcharge preloading is larger, and the radial consolidation coefficient is larger. However, if the vacuum preloading method is used excessively, the engineering cost is too high. Also, there is currently no standard available for guiding how the vacuum in combination with the surcharge preload should be planned. Therefore, the method for vacuum combined surcharge preloading in practical engineering can be scientifically and economically applied by researching the influence of different proportions and loading time arrangement on consolidation in vacuum combined surcharge preloading.
At present, no settling column tester which comprehensively utilizes pore pressure distribution measurement and combines vacuum preloading and surcharge preloading can be used.
Disclosure of Invention
The invention aims to solve the technical problem of overcoming the defects in the prior art and provides a settlement column tester combining vacuum preloading and surcharge preloading and a testing method.
In order to solve the problems, the solution of the invention is as follows:
the settling column tester combining vacuum preloading and surcharge preloading comprises a cylindrical hollow settling column for filling a soil sample; a circular transverse partition steel plate matched with the inner diameter of the sedimentation column is arranged in the middle of the sedimentation column, and a hollow rigid sleeve is fixedly connected to the center of the upper surface of the partition steel plate; the top of the rigid sleeve is connected with a displacement sensor, and the other end of the displacement sensor is fixed on the suspension bracket; the upper part of one drainage plate penetrates through the center of the partition steel plate and then is sleeved in the rigid sleeve, the part of the drainage plate, which is positioned below the partition steel plate, is buried in a soil sample, and the bottom end of the drainage plate is connected with the center of the bottom surface of the settling column; the drainage plate is provided with a drainage port and is connected to the outer side of the settling column through a drainage pipe;
a cover plate for sealing is arranged at an opening at the top of the settling column, and a rigid sleeve passes through a through hole in the center of the cover plate; a water sac made of a rubber film is arranged in a space between the cover plate and the partition steel plate, a water conduit is arranged at the top of the water sac, and the water conduit is connected to a water pump or a water pump after passing through a through hole on the cover plate and is used for filling or pumping water for pressing the bin into the water sac; vacuum tubes are arranged at a gap between the water bag and the side wall of the sedimentation column, the vacuum tubes are arranged at the top of the rigid sleeve, the two vacuum tubes are connected to a vacuum pump, and a vacuum gauge is arranged on the rigid sleeve;
a plurality of pore pressure sensors are arranged at the bottom and the side wall of the settling column connected with the soil sample; and the pore pressure sensor and the displacement sensor are connected to a data acquisition system through signal lines.
In the invention, pore pressure sensors at the bottom of a settling column are arranged in a sector occupying 1/4 of the area of a bottom surface, and 5 pore pressure sensors are arranged at equal intervals on a radius at intervals of 30 degrees; the hole pressure sensors are transversely arranged at intervals of 125mm on the side wall of the settling column, the number and the positions of each row of hole pressure sensors correspond to the hole pressure sensors arranged along the radius of the bottom surface, and the highest row of hole pressure sensors is arranged at the position of half of the height of the tester.
In the invention, a vacuum degree sensor is arranged from the bottom end of the drainage plate to the cover plate at intervals of 10cm, and each vacuum degree sensor is connected to a data acquisition system through a signal wire.
In the invention, a hydrophobic material coating is arranged on the inner surface of the settling column.
In the invention, a base capable of adjusting the level is arranged below the settling column.
In the invention, the cover plate and the opening at the top of the settling column are fixed through a buckle or a bolt, and a sealing gasket is arranged between the cover plate and the opening.
In the invention, a fixing device for positioning the drainage plate is arranged at the bottom of the settling column.
The invention further provides a settlement column test method combining vacuum preloading and preloading based on the settlement column tester, which is characterized in that the vacuum preloading and preloading pressures are applied to a soil sample, the vertical drainage channel is combined, the soil body is solidified, and the pore pressure and the displacement in the solidification process are monitored in real time to research the pore pressure change at different positions in the solidification process;
the test method specifically comprises the following steps:
(1) The drainage plate is arranged in a fixing device for positioning in the settling column, each sensor is connected to a data acquisition system, and accurate connection and no leakage are ensured;
(2) Filling a soil sample into the settling column, wherein the filling height is required to ensure that enough space is reserved for upper stacking;
(3) Placing the partition steel plate on the surface of the soil sample, and enabling the drainage plate to penetrate into the rigid sleeve; after the water bag is placed, a cover plate is installed, the sealing is checked, and a displacement sensor is installed;
(4) Injecting clear water into the water bag through a water pump, and closing the water pump and the valve after reaching a preset load;
(5) Opening a vacuum pump for vacuum pumping; meanwhile, opening a drainage valve of the drainage plate to drain pore water in the soil sample;
(6) The test is ended when one of the following conditions is reached:
the pressure value shown by the pore pressure sensor is kept unchanged for a period of time; or the settlement value shown by the displacement sensor is kept unchanged for a period of time; alternatively, there is no more porous water drain;
(7) And after the test is finished, recovering the soil for the test, cleaning the settling columns and processing the data obtained by the data acquisition system.
In the invention, the filling height is controlled, so that the soil sample is still higher than the highest pore pressure sensor after solidification.
The working principle of the invention is as follows: and during the test, changing the loading condition, monitoring the radial distribution and the settlement of the pore pressure of the consolidated soil sample, and obtaining the information related to the pore pressure in the consolidation process, thereby obtaining the relationship between the loading mode and the consolidation speed and the distribution and change relationship of the pore pressure at different positions.
Compared with the prior art, the invention has the beneficial effects that:
(1) The invention can effectively obtain the change of the pore pressure at different radial positions in the consolidation process for further research.
(2) The invention can simply and conveniently change the stacking value through water pressure control, and is convenient for researching the problems of different times and different sizes of stacking action.
(3) The invention has simple structure and is easy to operate. Model material and fill soil reuse can not cause waste and pollution to can the automatic recording data, reduce the required staff of experiment, reduce the error that produces when artifical reading simultaneously.
Drawings
FIG. 1 is a front sectional view of the tester of the present invention (not including a data acquisition system).
FIG. 2 is a side sectional view of the tester of FIG. 1.
FIG. 3 isbase:Sub>A top sectional view taken along line A-A in FIG. 1.
FIG. 4 is a top sectional view taken along line B-B in FIG. 1.
The reference numbers in the figures are: 1 displacement transducer (LVDT); 2, a rigid sleeve; 3, a water bag; 4, vacuum tube; 5, a water bag; 6, settling a column; 7, cutting off the steel plate; an 8-hole pressure sensor; 9 a drainage plate; 10, a base; 11 a cover plate; 12 a vacuum gauge.
Detailed Description
The settling column tester combining vacuum preloading and surcharge preloading in the invention is shown in figures 1-4. The tester comprises a cylindrical hollow settling column 6 for filling a soil sample; a circular transverse partition steel plate 7 matched with the inner diameter of the settling column 6 is arranged in the middle of the settling column, and a hollow rigid sleeve 2 is fixedly connected to the center of the upper surface of the partition steel plate 7; the top of the rigid casing 2 is connected with a displacement sensor 1, and the other end of the displacement sensor 1 is fixed on a suspension bracket; the upper part of one drainage plate 9 penetrates through the center of the partition steel plate 7 and then is sleeved in the rigid sleeve 2, the part of the drainage plate below the partition steel plate 7 is buried in a soil sample, and the bottom end of the drainage plate 9 is connected with the center of the bottom surface of the settling column 6; the drainage plate 9 is provided with a drainage port and is connected to the outer side of the settling column 6 through a drainage pipe;
a cover plate 11 for sealing is arranged at an opening at the top of the settling column 6, and the rigid sleeve 2 passes through a through hole in the center of the cover plate 11; a water bag 5 made of a rubber film is arranged in a space between the cover plate 11 and the partition steel plate 7, a water conduit is arranged at the top of the water bag 5 and is connected to a water pump or a water pump after passing through a through hole on the cover plate 11, the water pump is used for injecting water for pressing a bin into the water bag 5, and the water pump is used for pumping and discharging the water for pressing the bin from the water bag 5; a vacuum tube is arranged at a gap between the water bag 5 and the side wall of the settling column 6, the vacuum tube is arranged at the top of the rigid sleeve 2, the two vacuum tubes are connected to a vacuum pump, and a vacuum gauge 12 is arranged on the rigid sleeve 2;
the cover plate 11 and the opening at the top of the settling column 6 are fixed through a buckle or a bolt, and a sealing gasket is arranged between the cover plate and the opening. The inner surface of the settling legs 6 is provided with a coating of hydrophobic material. At the bottom of the settling leg 6, a fixture for positioning the drain plate 9 is provided. A base 10 capable of adjusting the level is arranged below the settling column 6.
A plurality of pore pressure sensors 8 are arranged at the bottom and the side wall of the settling column 6 connected with the soil sample; the pore pressure sensor 8 and the displacement sensor 1 are connected to a data acquisition system through signal lines. Pore pressure sensors 8 at the bottom of the settling column 6 are arranged in a sector occupying 1/4 of the area of the bottom surface, and 5 pore pressure sensors 8 are arranged at equal intervals on a radius at intervals of 30 degrees; a plurality of pore pressure sensors 8 which are transversely arranged are arranged on the side wall of the settling column 6 at intervals of 125mm, and the number and the positions of each row of pore pressure sensors 8 correspond to the pore pressure sensors 8 which are arranged along the radius of the bottom surface. From the bottom end of the drainage plate 9 to the cover plate 11, vacuum degree sensors are arranged at intervals of 10cm, and each vacuum degree sensor is connected to a data acquisition system through a signal line.
In the invention, a water pump, a water bag, corresponding pipelines and valves form a stacking pressure system which is used for applying stacking pressure to the soil sample loaded in the settling column 6. The vacuum pump, the vacuum pipe, the corresponding pipeline and the valve form a vacuum pressure system which is used for applying vacuum pressure to the soil sample filled in the settling column 6 and discharging water in the soil sample through the drainage plate 9 to solidify the soil body. Pore pressure changes of different measuring points in the consolidation process are measured by using the pore pressure sensor 8, and soil body settlement in the whole process is measured by using the displacement sensor 1, so that the rule that the pore pressure changes along with time and position is obtained. The tester can be used for researching pore pressure change and settlement development rules in the dredger fill consolidation process, and the test is easy to operate and has an intuitive result.
The method for testing the settling column based on the combination of the vacuum preloading and the surcharge preloading of the settling column tester comprises the steps of applying vacuum preloading and surcharge preloading pressure on a soil sample, combining a vertical drainage channel to enable a soil body to be solidified, monitoring the pore pressure and displacement in the solidification process in real time, and researching the change of the pore pressure at different positions in the solidification process;
the test method specifically comprises the following steps:
(1) The drainage plate 9 is arranged in a fixing device for positioning in the settling column 6, each sensor is connected to a data acquisition system, and accurate connection and no leakage are ensured;
(2) Filling a soil sample into the settling column 6, wherein the filling height is required to ensure that enough space is reserved for upper part stacking; the fill height is controlled so that the soil sample remains above the highest pore pressure sensor 8 after consolidation.
(3) Placing the partition steel plate 7 on the surface of the soil sample, and enabling the drainage plate 9 to penetrate into the rigid casing 2; after the water sac 5 is placed, a cover plate 11 is well installed, the sealing is checked, and the displacement sensor 1 is installed;
(4) Injecting clear water into the water bag 5 through a water pump, and closing the water pump and the valve after reaching a preset load;
(5) Opening a vacuum pump for vacuum pumping; meanwhile, opening a drainage valve of the drainage plate 9 to drain pore water in the soil sample;
(6) The test is ended when one of the following conditions is reached: the pressure value indicated by the pore pressure sensor 8 remains unchanged for a period of time; alternatively, the sedimentation value indicated by the displacement sensor 1 remains unchanged for a period of time; alternatively, there is no more interstitial water to drain;
(7) After the test is finished, the soil for the test is recovered, the settling columns 6 are cleaned, and the data acquired by the data acquisition system are processed.
The specific embodiment is as follows:
the method for testing and researching the improved dredger fill settling column is described in detail below with reference to the examples, and for convenience of explanation, the schematic diagram showing the structure of the device is not partially enlarged in general proportion and should not be taken as a limitation of the present invention, and in addition, in the actual manufacturing, three-dimensional space dimensions including length, width and height should be included.
The settling column 6 is a cylindrical glass container with an open top and a closed bottom, the inner diameter is 60cm, and the thickness of the side wall of the container is 1cm; the four radii at the bottom of the settling column 6, which are spaced by 30 degrees, are provided with 16 hole grooves, the side wall is provided with 4 rows of 4 holes grooves, each row has 4 x 4=16 holes grooves, the distance between the hole grooves in each row in height is 12.5cm, and the hole grooves are used for installing the hole pressure sensors 8. In order to avoid excessive friction caused by the inner wall during soil consolidation, the inner surface of the settling legs 6 is coated with a hydrophobic material to reduce the influence of the sidewall effect. In addition, an adjustable base 10 is placed below the settling column 6, and the base 10 is provided with a screw for adjusting the height to ensure that the bottom surface of the settling column 6 is in a horizontal position. The top of the settling leg 6 is provided with a cover plate 11 which is slightly larger than the cross section of the settling leg 6 and is provided with a flange seal for sealing.
The loading system comprises a stacking pressure system and a vacuum pressure system. Wherein the pile-loading pressure is mainly realized by injecting water into the cavity of the upper water bag 5 of the settling column 6 by using the water pump 3 and then transmitting the pressure to the surface of the lower soil sample through the partition steel plate 7. The vacuum pressure is connected to the vacuum pump 4 through a vacuum tube and the vacuum tube is connected to the drain plate 9 by a hand joint to provide a negative pressure in the drain plate 9. In order to avoid the reduction of the vacuum degree of the drainage plate 9 caused by the fact that the drainage plate 9 is exposed outside due to the fact that the partition steel plate 7 sinks along with the settlement of the soil body, a vacuum tube is also arranged on the upper portion of the drainage plate 9 and is connected with a vacuum pump, and therefore the vacuum degree of the whole space on the upper portion of the partition steel plate 7 is guaranteed.
The drainage system comprises a drainage plate 9 inserted in the center of the soil sample and a vacuum pump. Most of water in the soil sample is drained through the drainage plate 9, and the drainage plate 9 can be an integral plastic drainage plate commonly used in engineering. Care was taken to keep the drain board 9 in place and not bent during loading of the fill. A very small amount of water, which cannot be completely sealed off by the partition plate 7, enters the upper cavity from its edge, and is discharged through the vacuum tube. The drain board 9 is connected to the vacuum pipe through a hand-type sealing joint and a pipeline. The rigid sleeve 2 is made of metal and can be fixed on the partition steel plate 7 in a threaded connection or welding mode, and the inner diameter of the rigid sleeve is allowed to be embedded into the drainage plate 9.
The measuring system comprises pore pressure sensors 8 positioned on the side surfaces and the bottom surface of the settling column, a displacement sensor 1 connected to a partition steel plate 7 through a rigid sleeve 2, and a vacuum degree sensor arranged on a drainage plate. The pore pressure sensor 8 adopts a micro pore pressure sensor, a probe extends into the surface of the sedimentation column 6 from an opening, and a tail data line is left outside and connected with a data acquisition system; during the installation process, the distance between the probes needs to be paid attention to avoid contact between the probes. The displacement sensor 1 is connected to the partition steel plate 7 through the rigid casing 2 and driven by the partition steel plate 7 to sink, so that relevant data of the sink is obtained.
The data acquisition system automatically records the reading of the connected probe at regular intervals, and is used for reading and recording the pore pressure data at different moments. The data acquisition system can be implemented by using existing hardware, and those skilled in the art can utilize the existing technical means to implement the related functions according to the functions of the invention, which are not the focus of the invention and thus will not be described in detail.
The sealing and connecting system comprises a connection of a pore pressure sensor 8 and a settling column 9, a connection of a rigid sleeve 2 and a partition steel plate 7, a connection of the rigid sleeve 2 and a cover plate 11, and a connection of the cover plate 11 and the settling column 6. The connection between the pore pressure sensor 8 and the settling column 6 adopts an XX joint, the connection between the rigid sleeve 2 and the partition steel plate 7 adopts threaded connection or welding, the connection between the rigid sleeve 2 and the cover plate 11 adopts a method similar to cylinder piston sealing, and the sealing between the cover plate 11 and the settling column 6 adopts a method of flange connection and sealing by a sealing ring.
The improved dredger fill settling column test device and the test method can monitor the consolidation process of dredger fill in a settling column and the change of the pore pressure edge along with time and position in the process, and can also research the influence of the consolidation on the aspects by changing the proportion of two loading modes and the loading time.
The method specifically comprises the following steps:
(1) Checking and leveling a settling column: during the manufacturing process of the settling column 6, the probe of the pore pressure sensor 8 is fixed at a specified position and sealed. Therefore, before the test using the settling column 6, it is necessary to perform a tightness test of the mounting port of the pore pressure sensor 8. In addition, the partition steel plate 7 is put in and checked for a proper size. The horizontal height of the support 10 at the bottom of the settling column 6 is adjusted, so that the settling column 6 is horizontally placed.
(2) And (3) installing a monitoring system and a drainage system in the settling column: and connecting a tail end line of a probe of the pore pressure sensor 8 with a data acquisition system, and checking the sensors to check whether each sensor can work normally. The vertical drainage plate 9 is inserted into the middle of the settling column 6, so that simple fixation is performed, and the accuracy of the installation position is ensured.
(3) Filling soil: the field retrieved soil sample is loaded into the settling legs 6 and stopped when the test protocol is near the designated location.
(4) Installing a partition steel plate 7 and a settlement measuring device: placing the partition steel plate 7 and the rigid casing 2 connected with the partition steel plate above the soil body; firstly suspended, then the water bags 5 are arranged, the vacuum tube is connected with the drainage plate 9, and the other side is connected with a vacuum pump. The drainage plate 9 is connected with the vacuum pipe through a hand joint, and the two vacuum pipes are joined and then connected to the vacuum pump. And then slowly putting down the partition steel plate 7, the cover plate 11 and the displacement sensor 1 together for sealing and fastening.
(5) And starting to feed water, and starting to vacuumize after the water is about to fill the soil body, so that the soil body below the soil body starts to be solidified.
(6) The test is ended when one of the following conditions is reached: the pressure value indicated by the pore pressure sensor 8 remains unchanged for a period of time; alternatively, the sedimentation value indicated by the displacement sensor 1 remains unchanged for a period of time; alternatively, there is no more interstitial water to drain; all the above shows that the consolidation process is substantially completed.
(7) And after the test is finished, recovering the settling columns and the test soil, and performing data processing.
Precautions in the experiment:
(1) After the experiment is finished, starting the vacuum pump to try pumping, checking whether the working efficiency of the vacuum pump and the model test are tight or not, and taking corresponding sealing measures if air leakage occurs.
(2) The vacuum degree under the film in the sealing film should be stably maintained at 85KPa or more.
(3) Before the vacuum pump is started, the water valve must be opened, and the vacuum pump is forbidden to carry out anhydrous air transportation.
(4) When the test is finished, the power switch and the circulating water valve are cut off simultaneously, and the phenomenon of water flow suck-back is prevented.
Finally, it is to be noted that the above list is only one of the uses of the invention. In addition, the present invention may have many other uses. For example, water is pumped out of the process to indicate removal of the stack pressure, or the vacuum pump is turned off to indicate removal of the vacuum pressure. All modifications which can be derived or suggested by a person skilled in the art from the disclosure of the present invention are to be considered within the scope of the invention.
Claims (8)
1. A sedimentation column test method combining vacuum preloading and surcharge preloading is characterized in that the test method is realized based on the following sedimentation column tester:
the sedimentation column tester comprises a cylindrical hollow sedimentation column for filling a soil sample, wherein a circular transverse partition steel plate matched with the inner diameter of the sedimentation column is arranged in the middle of the sedimentation column, and a hollow rigid sleeve is fixedly connected to the central position of the upper surface of the partition steel plate; the top of the rigid sleeve is connected with a displacement sensor, and the other end of the displacement sensor is fixed on the suspension bracket; the upper part of one drainage plate penetrates through the center of the partition steel plate and then is sleeved in the rigid sleeve, the part of the drainage plate below the partition steel plate is buried in a soil sample, and the bottom end of the drainage plate is connected with the center of the bottom surface of the settling column; the drainage plate is provided with a drainage port and is connected to the outer side of the settling column through a drainage pipe;
a cover plate for sealing is arranged at an opening at the top of the settling column, and a rigid sleeve passes through a through hole in the center of the cover plate; a water sac made of a rubber film is arranged in a space between the cover plate and the partition steel plate, a water conduit is arranged at the top of the water sac, and the water conduit is connected to a water pump or a water pump after passing through a through hole on the cover plate so as to be used for filling or pumping water for pressing the bin into the water sac; vacuum tubes are arranged at the gap between the water bag and the side wall of the sedimentation column, the vacuum tubes are arranged at the top of the rigid sleeve, the two vacuum tubes are connected to a vacuum pump, and a vacuum gauge is arranged on the rigid sleeve;
a plurality of pore pressure sensors are arranged at the bottom and the side wall of the settling column connected with the soil sample; the pore pressure sensor and the displacement sensor are connected to a data acquisition system through signal lines;
the test method comprises the steps of applying vacuum preloading and surcharge preloading pressure to a soil sample, combining a vertical drainage channel to enable the soil body to be solidified, and researching the pore pressure change at different positions in the solidification process by monitoring the pore pressure and displacement in real time in the solidification process; the method specifically comprises the following steps:
(1) The drainage plate is arranged in a fixing device for positioning in the settling column, each sensor is connected to a data acquisition system, and accurate connection and no leakage are ensured;
(2) Filling a soil sample into the settling column, wherein the filling height is required to ensure that enough space is reserved for upper stacking;
(3) Placing the partition steel plate on the surface of the soil sample, and enabling the drainage plate to penetrate into the rigid sleeve; after the water bag is placed, a cover plate is installed, the sealing is checked, and a displacement sensor is installed;
(4) Injecting clear water into the water sac through the water pump, and closing the water pump and the valve after a preset load is reached;
(5) Opening a vacuum pump for vacuum pumping; meanwhile, opening a drainage valve of the drainage plate to drain pore water in the soil sample;
(6) The test is ended when one of the following conditions is reached:
the pressure value shown by the pore pressure sensor is kept unchanged for a period of time; or the settlement value shown by the displacement sensor is kept unchanged for a period of time; alternatively, there is no more interstitial water to drain;
(7) And after the test is finished, recovering the soil for the test, cleaning the settling columns and processing the data obtained by the data acquisition system.
2. The method according to claim 1, characterized in that the pore pressure sensors at the bottom of the settling legs are arranged in a sector of 1/4 of the floor area, 5 pore pressure sensors being arranged at equal intervals on a radius of 30 ° apart; and a plurality of pore pressure sensors which are transversely arranged are arranged on the side wall of the settling column at intervals of 125mm in height, and the number and the positions of each row of pore pressure sensors correspond to the pore pressure sensors arranged along the radius of the bottom surface.
3. The method of claim 1, wherein a vacuum degree sensor is arranged at an interval of 10cm from the bottom end of the drainage plate to the cover plate, and each vacuum degree sensor is connected to the data acquisition system through a signal wire.
4. A method according to any one of claims 1 to 3, characterized in that a coating of hydrophobic material is provided on the inner surface of the settling legs.
5. A method according to any one of claims 1 to 3, characterized in that a horizontally adjustable base is arranged below the settling legs.
6. A method according to any one of claims 1 to 3, characterised in that the cover plate is secured to the opening in the top of the settling leg by means of a snap or bolt, with a sealing gasket being provided between the two.
7. A method according to any one of claims 1 to 3, characterized in that fixing means for positioning the drainage plate are provided at the bottom of the settling leg.
8. A method according to any one of claims 1 to 3, wherein the fill height is controlled so that the sample remains above the highest pore pressure sensor after consolidation.
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| CN108008116B (en) * | 2017-12-06 | 2020-07-17 | 河海大学 | Vacuum preloading and electroosmosis combined test device |
| CN108693326A (en) * | 2018-03-30 | 2018-10-23 | 南京科兴新材料科技有限公司 | Soil displacement field and the visual experimental rig of seepage field and test method under a kind of simulation dyke building preloading |
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| CN110761267A (en) * | 2019-11-18 | 2020-02-07 | 清华大学 | Rapid prepressing and consolidating device and method for underwater soft soil foundation |
| CN111926794B (en) * | 2020-06-22 | 2022-04-01 | 温州大学 | Experimental device for measuring vacuum degree and pore pressure of soil body at certain point under vacuum consolidation state and test operation method thereof |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20090066498A (en) * | 2007-12-20 | 2009-06-24 | 삼성중공업 주식회사 | Test device for gas tightness of adhesion layer |
| WO2010028547A1 (en) * | 2008-09-11 | 2010-03-18 | 中国科学院武汉岩土力学研究所 | Stereoscopic network drainage device for accelerating water drainage consolidation velocity of hydraulic mud fill |
| CN202421109U (en) * | 2012-01-11 | 2012-09-05 | 清华大学 | Vacuum and electro-osmosis united consolidometer |
| CN103823039A (en) * | 2014-01-29 | 2014-05-28 | 王军 | Vacuum prepressing-overloading-dynamic compaction combined consolidometer |
| CN106840087A (en) * | 2017-02-24 | 2017-06-13 | 浙江大学 | For the settling column test instrument and test method of pore pressure distribution measuring |
-
2017
- 2017-07-22 CN CN201710603195.2A patent/CN107436140B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20090066498A (en) * | 2007-12-20 | 2009-06-24 | 삼성중공업 주식회사 | Test device for gas tightness of adhesion layer |
| WO2010028547A1 (en) * | 2008-09-11 | 2010-03-18 | 中国科学院武汉岩土力学研究所 | Stereoscopic network drainage device for accelerating water drainage consolidation velocity of hydraulic mud fill |
| CN202421109U (en) * | 2012-01-11 | 2012-09-05 | 清华大学 | Vacuum and electro-osmosis united consolidometer |
| CN103823039A (en) * | 2014-01-29 | 2014-05-28 | 王军 | Vacuum prepressing-overloading-dynamic compaction combined consolidometer |
| CN106840087A (en) * | 2017-02-24 | 2017-06-13 | 浙江大学 | For the settling column test instrument and test method of pore pressure distribution measuring |
Non-Patent Citations (1)
| Title |
|---|
| 汪小平 ; 吴洪贵 ; 王军 ; 符洪涛 ; .真空预压联合堆载法加固吹填淤泥地基室内试验研究.福建建筑.(第12期),全文. * |
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