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Underwater vacuum preloading centrifugal model testing device and method

A centrifugal model test and vacuum technology, which is applied in the field of foundation soil survey, soil protection, construction, etc., can solve the problem of not being able to simulate the site conditions well, the initial stress state of the soil cannot be simulated, and the end stress state of the simulated soil exists. Questions and other questions

Inactive Publication Date: 2011-04-13
CCCC FOURTH HARBOR ENG CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to the device, the vacuum pump needs to be started before the centrifuge is running, and the soil will not have time to consolidate under its own weight before vacuum preloading begins. At this time, the initial stress state of the soil cannot be simulated, and the deformation of the soil will be greatly affected. Impact
In 2006, Nishimatsu Construction Co., Ltd. of Japan also used a vacuum pump in the centrifuge to carry out vacuum well point dewatering preloading on the soil to test the underwater flow in the soil, which could not simulate the site conditions well. 86kPa
[0003] On the other hand, the existing technology of using a vacuum pump in the centrifuge to generate a vacuum to consolidate the soil can only make the pore water pressure decrease at the bottom of the test soil greater than the surface of the test soil, and the pore water pressure of the soil near the surface drops It can be seen that the soil at the bottom is better reinforced than the soil on the surface, and the pore water pressure on the surface of the soil does not drop or drops very little, which is inconsistent with the actual situation
Therefore, the existing vacuum preloading centrifugal model test device using a vacuum pump makes water seep downward in the soil, which cannot simulate the actual vacuum consolidation state of the soil, and the degree of vacuum obtained is not large.
Also due to the downward seepage of water in the soil, the horizontal displacement of the soil in the existing two centrifugal model tests cannot reflect the site conditions well, and the water level displacement is not well tested in the test
[0004] There are problems in the centrifugal simulation vacuum preloading test technology mentioned above. First, the vacuum degree obtained by the centrifugal model of the vacuum pump is small. Second, there are problems in simulating the initial stress state of the soil. Third, there are problems in simulating the final stress state of the soil. It is not possible to simulate underwater vacuum preloading

Method used

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  • Underwater vacuum preloading centrifugal model testing device and method
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Embodiment 1

[0058] Such as figure 1 , schematically shows an embodiment of the present invention that simulates the boundary range of the underwater vacuum preloading reinforcement zone.

[0059] Among them, the vertical pipe 2 is used to control the bottom water level. On the edge of the reinforcement area, the bottom water level is affected by the external water, which must be simulated. And around the reinforcement area, the sealing film is inserted into the test soil 8 to a depth of h6. In order to ensure that the water in the test soil 8 flows to the vertical drainage body 11 and the top filter pipe 28, the pipe connected to the bottom of the vertical connecting pipe 29 adopts a pressure-resistant plastic pipe and is connected with the air-water separation box 3. Reducing the pressure in the air-water separation box 3 can reduce the water head of the filter pipe 28, so that the water in the test soil 8 flows to the air-water separation box 3 through the filter pipe 28 and the longit...

Embodiment 2

[0061] Such as figure 2 , shows a double-sided drainage reinforcement embodiment of an underwater vacuum preloading reinforcement centrifugal model of the present invention. Among them, the vertical drainage body 11 penetrates the test soil 8 to connect the upper and lower horizontal drainage layers 7 and 9 of the test soil. At the same time, the filter pipes 28 are also distributed in the upper and lower horizontal drainage layers to play a double-sided drainage effect. Analytical solutions for vacuum preloading have a special role. The vertical water pipe 29 connecting the upper and lower drainage filter pipes 28 is a longitudinally compressible threaded pipe, which can be compressed in the longitudinal direction, but cannot be compressed in the cross section, so that the negative impact on the compression of the soil can be reduced without affecting the soil quality. The horizontal displacement of the body. The example vacuum is applied with figure 1 as shown.

Embodiment 3

[0063] Such as image 3 , shows an embodiment of the centrifugal test of the present invention simulating the full-section three-dimensional consolidation seepage of vacuum preloading. Wherein, the surrounding edges of the sealing film 12 are all inserted into the test soil 8, and the depth is h6. Since the four sides of the sealing film are inserted into the soil, the figure 1 and figure 2 The sealing frame 27 in can be canceled. The centrifugal test simulates three-dimensional underwater vacuum preloading, that is, the simulated on-site reinforcement area is small, and the soil deformation can no longer be simplified into plane strain and one-dimensional compressive strain, and the edge of the sealing membrane needs to be inserted into the soil.

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Abstract

The invention discloses an underwater vacuum preloading centrifugal model testing device and an underwater vacuum preloading centrifugal model testing method. The device comprises a centrifugal machine and also comprises an underwater soil body self-weight consolidation system and a vacuum driving system, wherein the underwater soil body self-weight consolidation system comprises a test model box loaded with soil body; and the vacuum driving system comprises a vacuum gas-water separation box, a vacuum aspirator pump, a rotating adapter, a high-pressure air supply device and the like. The invention can simulate soil body self-weight consolidation, namely can simulate an initial stress state of the soil body. Meanwhile, the invention adopts high-pressure air to acquire vacuum and is applied to centrifugal model testing technology, underwater vacuum preloading can be simulated, land vacuum preloading also can be simulated, vacuum preloading consolidation process and the final stress state of the consolidated soil body can be simulated, and the aim of testing underwater testing soil body displacement is fulfilled. The testing simulation can perform two-dimensional (namely a plane strain problem) or three-dimensional vacuum preloading-related simulation, and the internal stress and displacement field in a soil body consolidating area can be effectively measured.

Description

technical field [0001] The invention relates to a physical model test method and a model test device obtained by the method, especially a centrifugal model test device related to underwater vacuum preloading or vacuum preloading. Background technique [0002] Using a vacuum pump to generate a vacuum in a centrifuge and using the vacuum to seep out and consolidate the water in the soil is a vacuum preloading centrifugal model test. Because the vacuum pump is mechanically driven, the weight of each component in the centrifuge increases dozens of times, the vacuum pump is difficult to operate, and the vacuum pump needs to be turned on before starting the centrifuge, and the simulation of the self-weight consolidation of the test soil will be invalid, so it is used in the centrifuge There are only two examples of vacuum pump technology generating vacuum at home and abroad, which affects the in-depth study of vacuum preloading, especially underwater vacuum preloading theory. Acc...

Claims

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Application Information

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IPC IPC(8): E02D1/00E02D3/10
Inventor 胡利文
Owner CCCC FOURTH HARBOR ENG CO LTD
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