CN-117030407-B - Large-size saturated homogeneous sand sample preparation device and method

CN117030407BCN 117030407 BCN117030407 BCN 117030407BCN-117030407-B

Abstract

The invention discloses a large-size saturated homogeneous sand sample preparation device and method, comprising a frame assembly, a sand sample preparation assembly, a model box and a sand sample saturation assembly, wherein the frame assembly comprises a base, a vertical support, a transverse support and a connecting support, the transverse support is driven by a lifting driving device to move up and down, the sand sample preparation assembly comprises a rotary driving device and a shakeout box, the shakeout box is driven by the rotary driving device to rotate, a first sealing cover at the top of the model box is provided with a first exhaust valve, a geotechnical cloth is covered at a water inlet at the bottom of the model box and is connected with a water inlet valve, the sand sample saturation assembly comprises a vacuum pump and a sealing barrel, a second exhaust valve is arranged on a second sealing cover at the top of the sealing barrel and is connected with the vacuum pump, a drain valve is arranged at a drain outlet at the bottom of the sealing barrel and is connected with the water inlet valve. The invention can prepare the homogeneous saturated sand sample which is suitable for large-size model tests and meets the requirements of different compactibility.

Inventors

LI YUPING
FAN BAOYUN
TAO YU
JIA ZHIYUAN
SHI JIANYONG

Assignees

河海大学

Dates

Publication Date: 20260505
Application Date: 20230919

Claims (8)

1. The preparation device for the large-size saturated homogeneous sand sample is characterized by comprising a frame assembly, a sand sample preparation assembly, a model box and a sand sample saturation assembly; the frame assembly comprises a base, a vertical support, a transverse support and a connecting support, wherein the lower end of the vertical support is fixed on the base, the transverse support is arranged on the vertical support in a sliding manner and is driven by a lifting driving device to slide up and down along the vertical support, and the connecting support is fixedly connected to the transverse support; The sand sample preparation assembly comprises a rotary driving device and a sand-removing box, wherein the sand-removing box is connected below the connecting bracket and driven to rotate by the rotary driving device, a sand-removing plate is arranged at the bottom of the sand-removing box, a plurality of sand-removing holes are uniformly formed in the sand-removing plate, and a switch baffle capable of opening and closing to control sand removing is arranged at the bottom end of the sand-removing box; When the model box is arranged below the shakeout box, the shakeout box is driven to rotate through the rotary driving device, sand in the shakeout box can uniformly fall into the model box, a first detachable sealing cover is arranged at the top of the model box, a first exhaust valve is arranged on the first sealing cover, a water inlet is formed in the bottom of the model box, and geotechnical cloth is covered at the water inlet and connected with a water inlet valve; The sand sample saturation assembly comprises a vacuum pump and a sealing barrel, distilled water is contained in the sealing barrel, a second exhaust valve is arranged on a second sealing cover at the top of the sealing barrel and connected with the vacuum pump through a pipeline, the vacuum pump is connected with the first exhaust valve through a pipeline, a water outlet is formed in the bottom of the sealing barrel and provided with a water drain valve, and the water drain valve is connected with the water inlet valve through a pipeline.
2. The device for preparing the large-size saturated homogeneous sand sample according to claim 1, wherein the lifting driving device comprises a winding wheel, a suspension wire and a fixed pulley, a vertical guide rail is arranged on one side of the vertical support, the transverse support is arranged on the vertical guide rail in a sliding manner through the pulley, the winding wheel is arranged on the other side of the vertical support, the fixed pulley is arranged at the top of the vertical support, one end of the suspension wire is wound on the winding wheel, and the other end of the suspension wire is connected with the transverse support after bypassing the fixed pulley.
3. The device for preparing the large-size saturated homogeneous sand sample according to claim 1, wherein the front surface of the vertical support is provided with a graduated scale.
4. The device for preparing the large-size saturated homogeneous sand sample according to claim 1, wherein the first sealing cover is provided with a first pressure gauge, the second sealing cover is provided with a second pressure gauge, and the first sealing cover is a transparent sealing cover.
5. The device for preparing the large-size saturated homogeneous sand sample according to claim 1, wherein a sealing ring is arranged at the joint of the bottom of the first sealing cover and the model box, the first sealing cover is connected with the model box through two steel fixing clamps, and fastening screws are arranged on the steel fixing clamps and used for fastening and connecting the first sealing cover and the model box.
6. The device for preparing the large-size saturated homogeneous sand sample according to claim 1, wherein the shakeout box is a square iron box which is transparent from top to bottom, a plurality of equally-spaced small holes are formed in the lower parts of the front surface and the rear surface of the shakeout box, hard plastic rods are inserted into each pair of the small holes which are oppositely arranged, the shakeout plate is supported on each hard plastic rod, and the shakeout holes and the hard plastic rods are staggered.
7. The device for preparing the large-size saturated homogeneous sand sample according to claim 1, wherein the model box is a cylindrical steel barrel, a plurality of steel ribs are uniformly welded on the outer wall of the model box along the circumferential direction, two water inlets are respectively arranged on two sides of the bottom of the model box, and each water inlet is covered with geotechnical cloth and connected with one water inlet valve.
8. A method for preparing a large-size saturated homogeneous sand sample, which is characterized by adopting the large-size saturated homogeneous sand sample preparation device according to any one of claims 1-7, and comprising the following steps: S1, selecting a knockout plate with knockout holes with corresponding apertures according to the particle size of sample preparation sand particles, adjusting the knockout box height through the lifting driving device according to specific sand grading, further adjusting the knockout height, adjusting the rotating speed of the knockout box through adjusting the rotating speed of the rotating driving device, further adjusting the knockout speed, carrying out a relative compactness test on the thrown out sand, determining the knockout height and the knockout speed corresponding to the sand samples under different compactedness conditions, and selecting the proper knockout height and the proper knockout speed according to sand test sample preparation requirements; S2, closing the water inlet valve, after the shakeout height and the shakeout speed are determined, filling sand in the shakeout box, opening the switch baffle, opening a switch of the rotary driving device, starting the shakeout box to rotate according to the set rotation speed, and uniformly dropping the sand into the model box through the shakeout hole to prepare a sand sample; in the preparation process of the sand sample, the height of the sand-falling box is adjusted at any time through the lifting driving device, so that the sand-falling distance is always kept unchanged, and the sand-falling distance is the distance between the sand-falling plate and the sand surface; s3, after the preparation of the sand sample is completed, sealing and fixing the first sealing cover on the model box, opening the vacuum pump and the first exhaust valve, and exhausting air in the model box; S4, closing the drainage valve, filling distilled water in the sealed barrel, opening the vacuum pump and the second exhaust valve, and discharging air in the sealed barrel to prepare airless distilled water; And S5, connecting the drainage valve with the water inlet valve through a pipeline, opening the water inlet valve and the drainage valve, enabling airless distilled water in the sealed barrel to enter the model box until the sand sample is completely positioned below the water surface, completing preparation of the saturated sand sample, and closing the drainage valve and the water inlet valve.

Description

Large-size saturated homogeneous sand sample preparation device and method Technical Field The invention relates to the technical field of geotechnical tests, in particular to a device and a method for preparing a large-size saturated homogeneous sand sample. Background In the geotechnical engineering field, the sandy soil has the advantages of stable property, high recycling rate, controllable physical indexes such as grading and the like, and is widely applied to an indoor model test, but whether the compactness and uniformity of a sandy soil sample directly influence the reliability of a test result or not is good, so that a better preparation device and a better preparation method are required to be developed, and the sandy soil sample with good compactness and uniformity is prepared to meet the test requirement. At present, the indoor geotechnical test preparation method of the sand sample mainly comprises a vibration method, a compaction method, an inserting and tamping method, a sand rain method and the like, wherein the sand rain method can theoretically prepare a homogeneous sand sample deposited horizontally, but is limited by the defect of a sample preparation device, the samples prepared by the sand rain method at home and abroad still have a plurality of defects, for example, the sand sample preparation by throwing sand through a handheld funnel cannot be effectively controlled in throwing height and throwing speed, when the sand is removed through a fixed funnel, the size and the position of the sand outlet are difficult to adjust although the sand outlet can be controlled in height, the sand surface right below the sand outlet can be obviously higher than the periphery, so that the surface fluctuation of the sand sample is uneven, when the sand is removed through a rotatable funnel device, the sand outlet can be controlled, the sand outlet can still have only one surface, in addition, most of the fluctuation sample preparation devices are only suitable for preparing small-size samples, and the samples are easy to move in the manufacturing device, the requirements of uniformity and reproducibility are poor, the sample preparation process is poor, and the sample reproducibility is difficult to be repeatedly carried out, and the sample preparation is difficult to be carried out repeatedly. In the field of marine geotechnical engineering, saturated sandy soil is widely applied to indoor model tests, and is required to ensure good compactness and uniformity of sandy soil samples and to improve the saturation of sandy soil. The method comprises the steps of (1) adding a sufficient amount of saturated liquid into a model box, throwing sand particles into the model box, and in the sample preparation process, generating serious segregation phenomenon due to different deposition speeds of the sand particles in the liquid, so that the sample uniformity is poor, and (2) preparing a dry sand sample, and then carrying out vacuumizing saturation. Disclosure of Invention The invention aims to provide a device and a method for preparing a large-size saturated and homogeneous sand sample, which are used for solving the problems existing in the prior art and can be used for preparing the homogeneous and saturated sand sample which is suitable for large-size model tests and meets the requirements of different compactedness. In order to achieve the above object, the present invention provides the following solutions: the invention provides a large-size saturated homogeneous sand sample preparation device, which comprises a frame assembly, a sand sample preparation assembly, a model box and a sand sample saturation assembly, wherein the frame assembly is arranged on the frame assembly; the frame assembly comprises a base, a vertical support, a transverse support and a connecting support, wherein the lower end of the vertical support is fixed on the base, the transverse support is arranged on the vertical support in a sliding manner and is driven by a lifting driving device to slide up and down along the vertical support, and the connecting support is fixedly connected to the transverse support; The sand sample preparation assembly comprises a rotary driving device and a sand-removing box, wherein the sand-removing box is connected below the connecting bracket and driven to rotate by the rotary driving device, a sand-removing plate is arranged at the bottom of the sand-removing box, a plurality of sand-removing holes are uniformly formed in the sand-removing plate, and a switch baffle capable of opening and closing to control sand removing is arranged at the bottom end of the sand-removing box; When the model box is arranged below the shakeout box, the shakeout box is driven to rotate through the rotary driving device, sand in the shakeout box can uniformly fall into the model box, a first detachable sealing cover is arranged at the top of the model box, a first exhaust valve is arranged on the first sealing cover,