CN113640188A - Testing device and method for simulating in-situ stress field of clay stratum around pile - Google Patents
Testing device and method for simulating in-situ stress field of clay stratum around pile Download PDFInfo
- Publication number
- CN113640188A CN113640188A CN202110608394.9A CN202110608394A CN113640188A CN 113640188 A CN113640188 A CN 113640188A CN 202110608394 A CN202110608394 A CN 202110608394A CN 113640188 A CN113640188 A CN 113640188A
- Authority
- CN
- China
- Prior art keywords
- layer
- clay
- consolidation
- model box
- vacuum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
Abstract
The invention provides a test device and a method for simulating an in-situ stress field of clay stratum around a pile, which comprises the following steps: the consolidation model box is provided with a cavity for accommodating a clay layer, an upper functional layer and a lower functional layer are arranged in the cavity, the upper functional layer is positioned on the upper layer of the clay layer, and the lower functional layer is positioned on the lower layer of the clay layer; a model pile is vertically arranged in the cavity, and the lower end of the model pile is inserted into the clay layer from the upper functional layer; the strong seepage generating mechanism is connected with the consolidation model box and generates strong seepage to carry out seepage loading on a clay layer of the consolidation model box so as to consolidate the clay layer; the data monitoring and collecting component is used for collecting and monitoring a settlement value and a pore pressure value in the whole soil consolidation process of the consolidation model box so as to judge the soil consolidation progress. The method can effectively simulate the in-situ stress state of the clay stratum around the pile, can further develop the research of a scale model test on the basis, and has good application prospect in the fields of ocean engineering, geotechnical engineering and the like.
Description
Technical Field
The invention relates to the field of civil engineering model tests, in particular to a test device and a method for simulating an in-situ stress field of clay strata around a pile.
Background
In order to exploit energy, offshore wind power foundations, oil and gas exploitation platforms and the like, the installation and use are basically carried out in shallow soil in the seabed, so that the research on the service performance of the foundations or the platforms in the shallow soil in the seabed is of great significance for the development and utilization of ocean resources. Because the foundation and the platform are huge in size, if the experimental research is carried out in situ, the experimental research has the limiting conditions of high difficulty, less chance, high consumption of manpower and material resources and the like. Therefore, the stress field condition of the ocean in-situ soil body needs to be simulated under the laboratory condition.
A test device and a method for simulating an in-situ stress field of a clay stratum around a pile can simulate the stress field of an ocean in-situ soil body by providing a volume force for clay soil particles through seepage of water in the soil body. In addition, the seepage consolidation soil sample can also be prepared for a centrifuge test, so that the consolidation time in the centrifuge can be reduced; the pile foundation, the sinking pad foundation and the like can also be placed in the test device and combined with a water tank test to explore the seabed response and the like around the foundation under the action of waves.
Through the search of the prior art documents, li guangxi, epi-Lei et al introduced the basic principle and device of the seepage force model test in 1997, which utilizes the dragging effect of water on soil particles to provide volume force when the water seeps in the soil body, and in the downward seepage process, the model ratio is n ═ i +1, and i is the hydraulic gradient. Fox in Analysis of Hydraulic Gradient Effects for Laboratory Hydraulic Conductivity Testing (Geotechnical Testing Journal) provides a theoretical model, describes the influence of Hydraulic Gradient on permeability, deduces a relational expression of permeability coefficient along with the change of soil sample height under the condition of seepage force test, and provides a corresponding pore pressure, effective stress, pore ratio, Hydraulic Gradient and distribution equation of permeability according to the expression.
The mechanism that seepage flow produces the seepage flow volumetric force has been proved by theory, and this patent is applied the principle that seepage flow produces the volumetric force in the simulation of the in situ stress field in clay stratum.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a test device and a method for simulating an in-situ stress field of a clay stratum around a pile.
The first aspect of the invention provides a test device for simulating an in-situ stress field of a clay stratum around a pile, which comprises:
the consolidation model box is provided with a cavity for containing a clay layer, an upper functional layer and a lower functional layer are arranged in the cavity, the upper functional layer is positioned on the upper layer of the clay layer and used for preventing hydraulic fracture and preventing soil from upwards losing, the lower functional layer is positioned on the lower layer of the clay layer and used for ensuring uniform negative pressure on the bottom surface of the clay layer and preventing gravel from losing; a model pile is vertically arranged in the cavity, and the lower end of the model pile is inserted into the clay layer from the upper functional layer;
the strong seepage generating mechanism is connected with the consolidation model box and used for carrying out seepage loading on a clay layer of the consolidation model box to generate seepage force so as to consolidate the clay layer and simulate an in-situ stress field of clay stratum around a pile;
and the data monitoring and collecting component is used for collecting and monitoring a settlement value and a pore pressure value in the whole soil consolidation process in the consolidation model box so as to judge the soil consolidation progress.
Preferably, the upper functional layer is provided with a hard porous plate and a first filter paper plate in sequence from the upper layer to the lower layer; and the lower functional layer is sequentially provided with a second filter paper board, a reverse filter layer and a geotextile layer from the upper layer to the lower layer.
Preferably, the data monitoring and collecting component comprises a displacement meter and a pore pressure meter, wherein the displacement meter is connected with the hard porous plate and is used for collecting a settlement value in the whole soil consolidation process; the pore pressure meter is arranged on the side wall of the consolidation model box and is used for collecting the pore pressure value in the whole soil consolidation process.
Preferably, the consolidation model box is a rectangular structure with an open upper part, and a first through hole for mounting the pore pressure meter is formed in the side wall of the consolidation model box;
the bottom surface of the consolidation model box is provided with a second through hole, and the second through hole is connected with the strong seepage generating mechanism for draining and exhausting water;
and a supporting part for lifting the bottom surface is arranged at the bottom of the consolidation model box.
Preferably, the side wall of the consolidation model box is vertically and uniformly distributed with a plurality of rows of first through holes, so that the monitoring of the pore pressure values at different depths of the soil body is realized.
Preferably, the strong osmotic flow generating mechanism comprises:
a vacuum pump;
and the vacuum water tank is connected with the vacuum pump through a first pipeline and connected with the second through hole through a second pipeline, and the vacuum water tank is vacuumized through the vacuum pump, so that water and gas in the cavity of the consolidation model box are discharged into the vacuum water tank.
Preferably, a pressure regulating valve for regulating the vacuum degree of the vacuum water tank is arranged on the first pipeline;
the vacuum water tank is provided with a barometer for monitoring the vacuum degree of the vacuum water tank;
and a water stop valve is arranged on the second pipeline.
Preferably, the vacuum water tank is a columnar structure, and the columnar structure comprises:
the side wall is of a cylindrical structure made of transparent materials, and scale values are arranged on the side wall;
the upper cover plate is arranged on the upper end face of the side wall, the upper cover plate is connected with the upper end face of the side wall through a first connecting piece, and the upper cover plate is in sealing fit with the upper end face of the side wall;
the lower cover plate is arranged on the lower end face of the side wall, the lower cover plate is connected with the lower end face of the side wall through a second connecting piece, and the lower cover plate is in sealing fit with the lower end face of the side wall; the lower surface of the lower cover plate is provided with a foot pad, the position of the foot pad is consistent with the height of the bottom surface of the consolidation model box, and no water head difference between the foot pad and the bottom surface is ensured.
The second aspect of the invention provides a test method for simulating an in-situ stress field of a clay stratum around a pile, which comprises the following steps: the testing device for simulating the in-situ stress field of the clay stratum around the pile is adopted to carry out the following steps:
s1: smearing a lubricating medium on the inner wall of a cavity of a consolidation model box, sequentially putting a lower functional layer, a clay layer and an upper functional layer from bottom to top, inserting a model pile into the clay layer, then adding airless water into the cavity, enabling the water level to be higher than the upper surface of the upper functional layer, and keeping the water level unchanged during a test; a data monitoring and collecting component is arranged on the consolidation model box and is used for collecting a settlement value and a pore pressure value in the whole soil consolidation process;
s2: connecting a strong seepage generating mechanism with the consolidation model box, and carrying out seepage loading on a clay layer of the consolidation model box by the strong seepage generating mechanism to generate seepage force so that the clay layer starts to drain and consolidate under the action of pressure difference between the upper surface and the lower surface;
s3: adjusting the vacuum degree of the strong seepage generating mechanism, carrying out seepage loading on clay layers in a grading manner, and simultaneously acquiring a settlement value and a pore pressure value in the whole soil consolidation process through the data monitoring and acquiring part and outputting the settlement value and the pore pressure value to an external terminal;
s4: and when the settlement value of the clay layer is less than 0.1mm within the set time, judging that the soil consolidation is finished, reading the settlement value and comparing with the limited strain theory settlement, and when the difference between the two values is within the set value range, judging that the in-situ stress field of the clay layer around the pile is successfully simulated under the condition of 1 g.
Preferably, the S2: with strong seepage flow generation mechanism with the consolidation model case links to each other, through strong seepage flow generation mechanism generates strong seepage flow to the clay layer infiltration loading in the consolidation model case cavity, wherein, with strong seepage flow generation mechanism with the consolidation model case links to each other and includes: connecting a vacuum pump with a vacuum tank through a first pipeline, and installing a pressure regulating valve on the first pipeline for regulating the vacuum degree of the vacuum tank and controlling the magnitude of seepage force; the air pressure meter is arranged on the vacuum water tank and used for monitoring the vacuum degree of the vacuum water tank; connecting the vacuum water tank with the consolidation model box cavity through a second pipeline, and installing a water stop valve on the second pipeline; and after the strong seepage generating mechanism is connected with the consolidation model box, opening the vacuum pump, adjusting the pressure regulating valve to ensure that the vacuum water tank reaches the required vacuum degree, then opening the water stop valve, and starting drainage consolidation of the soil body under the action of the pressure difference between the upper surface and the lower surface at the moment.
Compared with the prior art, the invention has at least one of the following beneficial effects:
according to the device, the seepage force is generated in the consolidation model box by utilizing the pressure difference generated by the seepage suction force, the super-gravity field can be generated in the environment of 1g, the in-situ stress state of the clay stratum around the pile can be effectively simulated, and the research on the scale model test can be further developed on the basis; compared with the traditional centrifuge model test device, the device has the advantages of simple manufacture, economy, small size restriction of the model boxes, capability of simultaneously carrying out a plurality of model box tests, shortening unit test time, and freely adjusting vacuum degree, thereby initiating hydraulic gradient with different sizes and changing the scale ratio of the model.
The device solves the problem that the large-scale marine stratum in-situ test cannot be carried out due to the limiting factors such as high difficulty, few opportunities, high consumption of manpower and material resources and the like, can simulate the in-situ stress field of the shallow soil body in the ocean, and has accurate data, effective and simple method.
Drawings
Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:
fig. 1 is a schematic structural diagram of a test apparatus for simulating an in-situ stress field of a clay formation around a pile according to a preferred embodiment of the present invention;
FIG. 2 is a schematic view of the cavity of a consolidation model box with a data monitoring and acquisition component according to a preferred embodiment of the present invention;
FIG. 3a is a schematic diagram of the structure of a vacuum water tank in accordance with a preferred embodiment of the present invention;
FIG. 3b is a schematic structural diagram of an upper cover plate of a vacuum water tank in accordance with a preferred embodiment of the present invention;
FIG. 3c is a schematic structural view of a lower cover plate of a vacuum water tank in accordance with a preferred embodiment of the present invention;
FIG. 4 is a schematic structural view of a consolidation model box according to a preferred embodiment of the present invention;
the scores in the figure are indicated as: 1 is a vacuum pump, 2 is a pressure regulating valve, 3 is a barometer, 4 is a vacuum water tank, 5 is a stop valve, 6 is a displacement meter, 7 is a hard porous plate, 8a is a first filter paper board, 8b is a second filter paper board, 9 is a hole pressure meter, 10 is a consolidation model box, 11 is a reverse filter layer, 12 is a geotextile layer, 13 is a model pile, 14 is a data acquisition instrument, 41 is an upper cover plate, 42 is a side wall, 43 is a lower cover plate, 44 is a pad foot, 411 is a first screw hole, 412 is a first sealing washer, 431 is a second screw hole, 432 is a second sealing washer, 10-1 is a first through hole, and 10-2 is a second through hole.
Detailed Description
The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.
Referring to fig. 1, a test apparatus for simulating an in-situ stress field of a clay formation around a pile according to a preferred embodiment of the present invention includes: a consolidation model box 10, a strong seepage generating mechanism and a data monitoring and collecting component.
The consolidation model box 10 is provided with a cavity for accommodating a clay layer, and an upper functional layer and a lower functional layer are arranged in the cavity, wherein the upper functional layer is positioned on the upper layer of the clay layer and is used for preventing hydraulic fracture and upward loss of the clay body; lower functional layer is located the lower floor of clay layer, and lower functional layer is used for guaranteeing that clay layer bottom surface negative pressure is even and prevent that the gravel from losing. A model pile 13 is vertically arranged in the cavity, and the lower end of the model pile 13 is inserted into the clay layer from the upper functional layer; the strong seepage generating mechanism is connected with the consolidation model box, and generates seepage force by osmotic loading on a clay layer of the consolidation model box 10 to solidify the clay layer of the consolidation model box 10 so as to simulate an in-situ stress field of clay stratum around the pile, wherein the in-situ stress field is a stress field in which the shearing strength of the soil body without drainage is linearly increased along with the depth of the soil body.
The data monitoring and collecting component is used for collecting and monitoring a settlement value and a pore pressure value in the whole soil consolidation process in the consolidation model box 10 so as to judge the soil consolidation progress. As a preferred mode, under the condition that the conditions allow, when the pore pressure value is collected, the soil pressure value in the whole soil consolidation process is synchronously collected, and the stress value analysis of the soil consolidation is realized.
When the device is implemented specifically, according to specific test requirements, a clay body and water are added into the consolidation model box 10, seepage force is generated in the consolidation model box 10 by utilizing pressure difference generated by seepage suction, a supergravity field can be generated in a 1g environment, the in-situ stress state of a clay stratum around a pile can be effectively simulated, the scale model test research can be further developed on the basis, and the device has good application prospects in the fields of ocean engineering, geotechnical engineering and the like.
In other preferred embodiments, referring to fig. 2, the upper functional layer comprises a rigid porous plate 7 and a first filter plate 8a from the upper layer to the lower layer, wherein the rigid porous plate 7 is used for preventing hydraulic fracture, and the first filter plate 8a is used for preventing clay from flowing upwards; the lower functional layer comprises the following components from the upper layer to the lower layer in sequence: a second filter paper sheet 8b, a reverse filter layer 11 and a geotextile layer 12, wherein the reverse filter layer 11 may be a sand cushion. The second filter plate 8b is used for preventing clay layer and the inverted filter layer 11 from mixing, the inverted filter layer 11 is used for ensuring that the negative pressure on the bottom surface of the clay layer is uniform, and the geotextile layer 12 is used for preventing the gravel loss of the inverted filter layer 11.
In other preferred embodiments, referring to fig. 2, the data monitoring and collecting component comprises a displacement meter 6 and a pore pressure meter, wherein the displacement meter 6 is connected with a hard porous plate 7 and is used for collecting a settlement value in the whole soil consolidation process; the pore pressure meter 9 is arranged on the side wall of the consolidation model box 10 and is used for collecting the pore pressure value in the whole soil consolidation process. Preferably, a soil pressure gauge is further disposed on the sidewall of the consolidation model box 10 for collecting the soil pressure value during the whole soil consolidation process. And outputting the settlement value, the pore pressure value and the soil pressure value of the collected soil body in the whole process of consolidation to external terminal equipment through a data monitoring and collecting component. The data monitoring and collecting component also comprises a data collector 14 for recording the data collected by the displacement meter 6, the pore pressure meter 9 and the soil pressure meter and transmitting the collected data to an external terminal.
In other partially preferred embodiments, and as shown in fig. 2 and 4, the consolidation model box 10 is a rectangular box body, the upper part of which is open and completely open. The side wall of the rectangular box body is provided with a first through hole 10-1, and the first through hole 10-1 is used for installing a hole pressure gauge 9 and a soil pressure gauge. In one example, the rectangular box has a length, width and height of 700mm, 200mm and 400mm respectively.
The bottom surface of the rectangular box body is provided with a second through hole 10-2, and the second through hole 10-2 is connected with the strong seepage generating mechanism for draining and exhausting water. Preferably, two or more holes are uniformly arranged on the bottom surface of the rectangular box body for draining and exhausting water and gas. When setting up a plurality of hole sites, all be connected every hole site with vacuum water tank 4, guarantee that the pore pressure of rectangle box bottom surface is as even as possible, the diffusion of 11 pairs of negative pressure of rethread anti-filter layer for the negative pressure that transmits the muck layer bottom is even.
The bottom of the rectangular box body is provided with a supporting part for lifting the bottom surface of the rectangular box body. Preferably, the support portion includes feet 44 mounted at four corners of the rectangular case bottom.
In other preferred embodiments, referring to fig. 4, a plurality of rows of first through holes 10-1 are uniformly distributed along the vertical direction on the sidewall of the consolidation model box 10, and one or two holes may be provided in each row. Through vertically arranging a plurality of rows of first through holes 10-1, the monitoring of the hole pressure values at different depths can be realized.
In some other preferred embodiments, the strong osmotic flow generating mechanism comprises: the vacuum pump 1 and the vacuum water tank 4, wherein the vacuum water tank 4 is connected with the vacuum pump 1 through a first pipeline, the vacuum water tank 4 is connected with the second through hole 10-2 through a second pipeline, and the vacuum water tank 4 is pumped by the vacuum pump 1 to exhaust water and gas in the cavity of the consolidation model box 10 into the vacuum water tank 4.
In other preferred embodiments, the first pipeline is provided with a pressure regulating valve 2 for regulating the vacuum degree of the vacuum water tank 4; a barometer for monitoring the vacuum degree of the vacuum water tank 4 is arranged on the vacuum water tank 4; and a water stop valve 5 is arranged on the second pipeline and used for connecting or disconnecting the second pipeline. In specific implementation, when the vacuum degree of the vacuum water tank 4 reaches the required vacuum degree, the water stop valve 5 is opened, and the soil body in the consolidation model box 10 cavity starts to drain water and consolidate under the action of the pressure difference between the upper surface and the lower surface. As a preferred mode, the first pipeline and the second pipeline can both adopt PU pipelines. A vacuum pump 1, a pressure regulating valve 2, a vacuum water tank 4, a water stop valve 5 and a consolidation model box 10 are connected with a pneumatic plug through a PU pipeline in sequence. In specific implementation, a first pneumatic plug is arranged at a second through hole 10-2 at the bottom of the consolidation model box 10, so that water and air leakage cannot occur after the second through hole 10-2 is connected with a second pipeline; two sides of the water stop valve 5 on the second pipeline are respectively provided with a second pneumatic plug for connecting the water stop valve 5 with the PU pipeline; a third pneumatic plug is arranged at a second screw hole 431 at the bottom of the vacuum water tank 4 and is connected with the PU pipeline to the water stop valve 5; the two first screw holes 411 on the upper part of the vacuum water tank 4 are provided with fourth pneumatic plugs for connecting PU pipelines, and the corresponding pipelines are respectively connected to the barometer 3 and the pressure regulating valve 2; fifth pneumatic plugs are respectively arranged on two sides of the pressure regulating valve 2 and used for connecting the PU pipeline; and a sixth pneumatic plug is also arranged on the vacuum pump 1 and is used for connecting the first pipeline.
In other partially preferred embodiments, the vacuum reservoir 4 is a cylindrical structure. Referring to fig. 3a, the vacuum water tank 4 is formed by splicing a side wall 42, an upper cover plate 41 and a lower cover plate 43. The side wall 42 is a cylindrical structure made of transparent materials, and scale values are arranged on the side wall 42; preferably, the transparent material is high-strength glass. The upper cover plate 41 is disposed on the upper end surface of the sidewall 42, the upper cover plate 41 is connected to the upper end surface of the sidewall 42 through a first connecting member, and a first sealing gasket 412 is disposed between the upper cover plate 41 and the upper end surface of the sidewall 42, so that the upper cover plate 41 and the upper end surface of the sidewall 42 are in sealing engagement. In one embodiment, the dimensional parameters of the sidewalls 42 are: the height of the cylindrical structure is 1500mm, and the inner diameter and the outer diameter are 391mm and 400mm respectively.
The lower cover plate 43 is arranged on the lower end face of the side wall 42, the lower cover plate 43 is connected with the lower end face of the side wall 42 through a second connecting piece, a second sealing washer 432 is arranged between the lower cover plate 43 and the lower end face of the side wall 42, and sealing fit is achieved between the lower cover plate 43 and the lower end face of the side wall 42; the lower surface of the lower cover plate 43 is provided with a foot pad 44, and the position of the foot pad 44 is consistent with the height of the bottom surface of the consolidation model box 10, so that no water head difference is ensured between the foot pad and the bottom surface.
Preferably, the upper cover plate 41 and the lower cover plate 43 may be made of metal. The first connecting piece and the second connecting piece are both high-strength bolt rods. The side wall 42, the upper cover body 41 and the lower cover body 43 are connected and fixed together by four high-strength bolt rods in a screwing mode, and the overall stability and the sealing performance are guaranteed. Referring to fig. 3b, two first screw holes 411 are formed in the upper cover plate 41 for respectively connecting the pressure regulating valve 2 and the barometer 3. Referring to fig. 3c, a second screw hole 431 is formed in the lower cover plate 43 to connect the water stop valve 5.
Another embodiment provides a test method for simulating an in-situ stress field of a clay formation around a pile, including: the testing device for simulating the in-situ stress field of the clay stratum around the pile is adopted, and the testing device is executed according to the following steps:
s1: referring to fig. 1 and 2, a lubricating medium (commercially available lubricating oil can be used) is applied to the inner wall of the cavity of the consolidation model box 10, and a geotextile 12, a sand cushion layer 11, a filter paper plate 8, a clay body (i.e., clay layer), a filter paper plate 8 and a hard porous plate 7 are sequentially placed from bottom to top; inserting the model pile 13 into the clay layer, then adding airless water into the cavity, enabling the water level to be higher than the upper surface of the upper functional layer, and keeping the water level constant during the test; a pore pressure meter 9 and a soil pressure meter are arranged on the side wall of the consolidation model box 10 and are used for collecting the pore pressure value and the soil pressure value in the whole soil consolidation process; and a displacement meter 6 is arranged at the upper part of the consolidation model box 10, and the displacement meter 6 is connected with a hard porous plate 7 and is used for collecting a settlement value in the whole soil consolidation process.
S2: the strong seepage generating mechanism is connected with the consolidation model box 10, and seepage force is generated by osmotic loading of a clay layer in the cavity of the consolidation model box 10 through the strong seepage generating mechanism, so that the clay layer starts to drain water and consolidate under the action of pressure difference between the upper surface and the lower surface.
S3: and adjusting the vacuum degree of the strong seepage generating mechanism, carrying out seepage loading on the clay layer in a grading manner (namely controlling the seepage force to change from small to large), and simultaneously acquiring a settlement value, a pore pressure value and a soil pressure value in the whole soil body consolidation process through the data monitoring and acquiring component and outputting the settlement value, the pore pressure value and the soil pressure value to an external computer.
S4: and when the settlement value of the soil body is less than 0.1mm within 48 hours, judging that the soil body is solidified, reading the settlement value and comparing with the limited strain theory settlement, and when the difference between the two numerical values is within a set value range, judging that the in-situ stress field of the clay stratum around the pile is simulated successfully under the condition of 1 g.
Step S3, vacuum loading of clay layers: the seepage force generated in the clay layer is controlled by controlling different vacuum degrees, namely the seepage force is controlled to change from small to large. The adoption of the graded vacuum loading can prevent hydraulic fracture and simultaneously prevent the clay body from upwards losing due to overlarge initial seepage force. If the vacuum loading is not graded, but a larger vacuum degree is directly adopted, the seepage force is too large, so that the clay layer is subjected to hydraulic fracture and the soil body is lost upwards.
In other partially preferred embodiments, S2: link to each other strong seepage flow generation mechanism and consolidation model case 10, generate strong seepage flow to the clay layer infiltration loading in consolidation model case 10 cavity through strong seepage flow generation mechanism, wherein, link to each other strong seepage flow generation mechanism and consolidation model case 10 and include: the vacuum pump 1 is connected with a vacuum box through a first pipeline, and a pressure regulating valve 2 is arranged on the first pipeline and used for regulating the vacuum degree of a vacuum water tank 4 and controlling the magnitude of seepage force; the barometer 3 is arranged on the vacuum water tank 4 and used for monitoring the vacuum degree of the vacuum water tank 4; connecting the vacuum water tank 4 with the cavity of the consolidation model box 10 through a second pipeline, and installing a water stop valve 5 on the second pipeline; after the strong seepage generating mechanism is connected with the consolidation model box 10, the vacuum pump 1 is opened, the pressure regulating valve 2 is regulated to enable the vacuum water tank 4 to reach the required vacuum degree, then the water stop valve 5 is opened, and at the moment, the soil body of the clay layer starts to drain water and consolidate under the action of the pressure difference between the upper surface and the lower surface.
The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.
Claims (10)
1. The utility model provides a test device of simulation stake week clay stratum normal position stress field which characterized in that includes:
the consolidation model box is provided with a cavity for containing a clay layer, an upper functional layer and a lower functional layer are arranged in the cavity, the upper functional layer is positioned on the upper layer of the clay layer and used for preventing hydraulic fracture and preventing soil from upwards losing, the lower functional layer is positioned on the lower layer of the clay layer and used for ensuring uniform negative pressure on the bottom surface of the clay layer and preventing gravel from losing; a model pile is vertically arranged in the cavity, and the lower end of the model pile is inserted into the clay layer from the upper functional layer;
the strong seepage generating mechanism is connected with the consolidation model box and used for carrying out seepage loading on a clay layer of the consolidation model box to generate seepage force so as to consolidate the clay layer and simulate an in-situ stress field of clay stratum around a pile;
and the data monitoring and collecting component is used for collecting and monitoring a settlement value and a pore pressure value in the whole soil consolidation process in the consolidation model box so as to judge the soil consolidation progress.
2. The test device for simulating the in-situ stress field of the clay stratum around the pile according to claim 1, wherein the upper functional layer is provided with a hard porous plate and a first filter plate in sequence from the upper layer to the lower layer; and the lower functional layer is sequentially provided with a second filter paper board, a reverse filter layer and a geotextile layer from the upper layer to the lower layer.
3. The test device for simulating the in-situ stress field of the clay stratum around the pile according to claim 2, wherein the data monitoring and collecting component comprises a displacement meter and a pore pressure meter, wherein the displacement meter is connected with the hard porous plate and is used for collecting a settlement value in the whole soil consolidation process; the pore pressure meter is arranged on the side wall of the consolidation model box and is used for collecting the pore pressure value in the whole soil consolidation process.
4. The test device for simulating the in-situ stress field of the clay stratum around the pile according to claim 2, wherein the consolidation model box is of a rectangular structure with an open upper part, and a first through hole for mounting the pore pressure gauge is formed in the side wall of the consolidation model box;
the bottom surface of the consolidation model box is provided with a second through hole, and the second through hole is connected with the strong seepage generating mechanism for draining and exhausting water;
and a supporting part for lifting the bottom surface is arranged at the bottom of the consolidation model box.
5. The test device for simulating the in-situ stress field of the clay stratum around the pile according to claim 4, wherein a plurality of rows of first through holes are uniformly distributed on the side wall of the consolidation model box along the vertical direction, so that the monitoring of the hole pressure values at different depths of a soil body is realized.
6. The test device for simulating in-situ stress field of clay stratum around pile according to claim 4, wherein the strong seepage generating mechanism comprises:
a vacuum pump;
and the vacuum water tank is connected with the vacuum pump through a first pipeline and connected with the second through hole through a second pipeline, and the vacuum water tank is vacuumized through the vacuum pump, so that water and gas in the cavity of the consolidation model box are discharged into the vacuum water tank.
7. The test device for simulating the in-situ stress field of the clay stratum around the pile according to claim 4, wherein a pressure regulating valve for regulating the vacuum degree of the vacuum water tank is arranged on the first pipeline;
the vacuum water tank is provided with a barometer for monitoring the vacuum degree of the vacuum water tank;
and a water stop valve is arranged on the second pipeline.
8. The test device for simulating in-situ stress field of clay stratum around pile according to claim 4, wherein the vacuum water tank is a columnar structure, and the columnar structure comprises:
the side wall is of a cylindrical structure made of transparent materials, and scale values are arranged on the side wall;
the upper cover plate is arranged on the upper end face of the side wall, the upper cover plate is connected with the upper end face of the side wall through a first connecting piece, and the upper cover plate is in sealing fit with the upper end face of the side wall;
the lower cover plate is arranged on the lower end face of the side wall, the lower cover plate is connected with the lower end face of the side wall through a second connecting piece, and the lower cover plate is in sealing fit with the lower end face of the side wall; the lower surface of the lower cover plate is provided with a foot pad, the position of the foot pad is consistent with the height of the bottom surface of the consolidation model box, and no water head difference between the foot pad and the bottom surface is ensured.
9. A test method for simulating an in-situ stress field of a clay stratum around a pile is characterized by comprising the following steps: the test device for simulating the in-situ stress field of the clay stratum around the pile is adopted, and the test device is implemented according to the following steps:
s1: smearing a lubricating medium on the inner wall of a cavity of a consolidation model box, sequentially putting a lower functional layer, a clay layer and an upper functional layer from bottom to top, inserting a model pile into the clay layer, then adding airless water into the cavity, enabling the water level to be higher than the upper surface of the upper functional layer, and keeping the water level unchanged during a test; a data monitoring and collecting component is arranged on the consolidation model box and is used for collecting a settlement value and a pore pressure value in the whole soil consolidation process;
s2: connecting a strong seepage generating mechanism with the consolidation model box, and carrying out seepage loading on a clay layer of the consolidation model box by the strong seepage generating mechanism to generate seepage force so that the clay layer starts to drain and consolidate under the action of pressure difference between the upper surface and the lower surface;
s3: adjusting the vacuum degree of the strong seepage generating mechanism, carrying out seepage loading on clay layers in a grading manner, and simultaneously acquiring a settlement value and a pore pressure value in the whole soil consolidation process through the data monitoring and acquiring part and outputting the settlement value and the pore pressure value to an external terminal;
s4: and when the settlement value of the clay layer is less than 0.1mm within the set time, judging that the soil consolidation is finished, reading the settlement value and comparing with the limited strain theory settlement, and when the difference between the two values is within the set value range, judging that the in-situ stress field of the clay layer around the pile is successfully simulated under the condition of 1 g.
10. The test method for simulating in-situ stress field of clay formation around pile according to claim 9, wherein the S2: with strong seepage flow generation mechanism with the consolidation model case links to each other, through strong seepage flow generation mechanism generates strong seepage flow to the clay layer infiltration loading in the consolidation model case cavity, wherein, with strong seepage flow generation mechanism with the consolidation model case links to each other and includes: connecting a vacuum pump with a vacuum tank through a first pipeline, and installing a pressure regulating valve on the first pipeline for regulating the vacuum degree of the vacuum tank and controlling the magnitude of seepage force; the air pressure meter is arranged on the vacuum water tank and used for monitoring the vacuum degree of the vacuum water tank; connecting the vacuum water tank with the consolidation model box cavity through a second pipeline, and installing a water stop valve on the second pipeline; and after the strong seepage generating mechanism is connected with the consolidation model box, opening the vacuum pump, adjusting the pressure regulating valve to ensure that the vacuum water tank reaches the required vacuum degree, then opening the water stop valve, and starting drainage consolidation of the soil body under the action of the pressure difference between the upper surface and the lower surface at the moment.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110608394.9A CN113640188B (en) | 2021-06-01 | 2021-06-01 | Testing device and method for simulating in-situ stress field of clay stratum around pile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110608394.9A CN113640188B (en) | 2021-06-01 | 2021-06-01 | Testing device and method for simulating in-situ stress field of clay stratum around pile |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113640188A true CN113640188A (en) | 2021-11-12 |
| CN113640188B CN113640188B (en) | 2022-09-20 |
Family
ID=78415882
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110608394.9A Active CN113640188B (en) | 2021-06-01 | 2021-06-01 | Testing device and method for simulating in-situ stress field of clay stratum around pile |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113640188B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114295468A (en) * | 2022-01-07 | 2022-04-08 | 中国石油大学(华东) | Variable-head soft clay consolidation model test box and use method thereof |
Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103306268A (en) * | 2013-05-23 | 2013-09-18 | 南京盼源工程技术有限公司 | Anti-blocking controllable negative pressure quick solidifying system for flow state dredging silt |
| CN103389249A (en) * | 2013-07-18 | 2013-11-13 | 河海大学 | Device and method for clay core wall hydraulic fracturing experiments |
| CN103953074A (en) * | 2014-04-28 | 2014-07-30 | 青岛理工大学 | Opened tubular pile hammering injection and static load simulation experiment device and method |
| CN106769500A (en) * | 2016-11-25 | 2017-05-31 | 天津大学 | A kind of ground permeates the test method of gas pressure consolidation |
| CN106840086A (en) * | 2017-02-22 | 2017-06-13 | 天津城建大学 | The rapidly solidified weak soil experimental rig of low Low Level vacuum method |
| CN207379851U (en) * | 2017-11-11 | 2018-05-18 | 广州环保投资集团有限公司 | Cyclic load load testing machine based on transparent soil model |
| CN108414728A (en) * | 2018-02-07 | 2018-08-17 | 南京科兴新材料科技有限公司 | Weak soil displacement field and the visual experimental rig of seepage field and test method under a kind of vacuum method |
| CN109344547A (en) * | 2018-11-08 | 2019-02-15 | 同济大学 | Freezing process design methods and device under a kind of seepage effect of combination stratum |
| CN109632518A (en) * | 2019-01-19 | 2019-04-16 | 天津大学 | Temperature field-stress field-seepage field couples consolidation test equipment |
| CN109632519A (en) * | 2019-01-19 | 2019-04-16 | 天津大学 | Temperature field-seepage field couples permeability test method |
| CN109853646A (en) * | 2019-04-02 | 2019-06-07 | 江苏省地质矿产局第三地质大队 | Indoor simulation test device and method for confined water precipitation of foundation pit |
| CN110221042A (en) * | 2019-06-27 | 2019-09-10 | 合肥工业大学 | A kind of device of simulating excavation stress field and Analysis of Ground-water Seepage Field coupling effect |
| WO2020048408A1 (en) * | 2018-09-04 | 2020-03-12 | 大连理工大学 | Device for measuring strength and strain softening parameters of saturated clay specimen on basis of full-flow penetration testing |
-
2021
- 2021-06-01 CN CN202110608394.9A patent/CN113640188B/en active Active
Patent Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103306268A (en) * | 2013-05-23 | 2013-09-18 | 南京盼源工程技术有限公司 | Anti-blocking controllable negative pressure quick solidifying system for flow state dredging silt |
| CN103389249A (en) * | 2013-07-18 | 2013-11-13 | 河海大学 | Device and method for clay core wall hydraulic fracturing experiments |
| CN103953074A (en) * | 2014-04-28 | 2014-07-30 | 青岛理工大学 | Opened tubular pile hammering injection and static load simulation experiment device and method |
| CN106769500A (en) * | 2016-11-25 | 2017-05-31 | 天津大学 | A kind of ground permeates the test method of gas pressure consolidation |
| CN106840086A (en) * | 2017-02-22 | 2017-06-13 | 天津城建大学 | The rapidly solidified weak soil experimental rig of low Low Level vacuum method |
| CN207379851U (en) * | 2017-11-11 | 2018-05-18 | 广州环保投资集团有限公司 | Cyclic load load testing machine based on transparent soil model |
| CN108414728A (en) * | 2018-02-07 | 2018-08-17 | 南京科兴新材料科技有限公司 | Weak soil displacement field and the visual experimental rig of seepage field and test method under a kind of vacuum method |
| WO2020048408A1 (en) * | 2018-09-04 | 2020-03-12 | 大连理工大学 | Device for measuring strength and strain softening parameters of saturated clay specimen on basis of full-flow penetration testing |
| CN109344547A (en) * | 2018-11-08 | 2019-02-15 | 同济大学 | Freezing process design methods and device under a kind of seepage effect of combination stratum |
| CN109632518A (en) * | 2019-01-19 | 2019-04-16 | 天津大学 | Temperature field-stress field-seepage field couples consolidation test equipment |
| CN109632519A (en) * | 2019-01-19 | 2019-04-16 | 天津大学 | Temperature field-seepage field couples permeability test method |
| CN109853646A (en) * | 2019-04-02 | 2019-06-07 | 江苏省地质矿产局第三地质大队 | Indoor simulation test device and method for confined water precipitation of foundation pit |
| CN110221042A (en) * | 2019-06-27 | 2019-09-10 | 合肥工业大学 | A kind of device of simulating excavation stress field and Analysis of Ground-water Seepage Field coupling effect |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114295468A (en) * | 2022-01-07 | 2022-04-08 | 中国石油大学(华东) | Variable-head soft clay consolidation model test box and use method thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN113640188B (en) | 2022-09-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Wang et al. | Vertical performance of suction bucket foundation for offshore wind turbines in sand | |
| CN108088982A (en) | Simulate the Experimental Method in Laboratory of fine grained seepage inflow erosion inside deep aquifers sand | |
| CN106988352A (en) | A kind of method of testing for considering soil body preconsolidation and the horizontal bearing capacity of single pile under cyclic load | |
| CN103091471B (en) | A kind of model accelerating rinse fill consolidation and test method thereof | |
| Zhang et al. | Effect of seepage on the penetration resistance of bucket foundations with bulkheads for offshore wind turbines in sand | |
| Wang et al. | Lateral capacity assessment of offshore wind suction bucket foundation in clay via centrifuge modelling | |
| CN113640188B (en) | Testing device and method for simulating in-situ stress field of clay stratum around pile | |
| Li et al. | Experimental study on the vertical deformation of sand caused by cyclic withdrawal and recharging of groundwater | |
| CN115341589A (en) | Pile foundation bearing characteristic test device considering high stratum stress influence and using method | |
| WIN et al. | One-dimension compression of slurry with radial drainage | |
| Sedlacek et al. | Geotechnical stability of gravity base foundations for offshore wind turbines on granular soils | |
| Ren et al. | Model-scale tests to examine water pressures acting on potentially buoyant underground structures in clay strata | |
| Zhuo et al. | Stability of long trench in soft soils by bentonite-water slurry | |
| CN211200492U (en) | Near-sea foundation pit supporting structure model test device | |
| CN210917495U (en) | Test device for bearing performance of cast-in-situ bored pile in water-containing soil body | |
| Sassa et al. | Response of saturated/unsaturated gravelly sand to tidal fluctuations | |
| HAM | 4.4 Field Testing for Evaluation of Landfill Gas Yields | |
| Chan et al. | Centrifuge simulation of heave behaviour of deep basement slabs in overconsolidated clay | |
| 鲁晓兵 et al. | Experimental study of pore pressure and deformation of suction bucket foundations under horizontal dynamic loading | |
| CN109063334A (en) | A kind of fluid structure interaction mode construction method of LOW PERMEABILITY POROUS MEDIA material | |
| Zhang et al. | Research on the Effective Control of Ground Settlement during Double-Layered Foundation Pit Dewatering Based on Seepage Control-Recharge Coupling Model | |
| CN211849650U (en) | Limit uplift bearing capacity test device of uplift pile under seepage flow condition | |
| CN212358402U (en) | Offshore type barrel foundation simulation test model device | |
| CN110579586B (en) | Unsaturated soil-water-gas two-phase flow migration experimental instrument and method under loading and unloading disturbance | |
| CN210199104U (en) | Experimental device for be used for simulating loess foundation settlement dynamic change |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |