阅读说明：本技术 一种套筒式多阶砂雨装置及砂样制备方法 (Sleeve type multistage sand rain device and sand sample preparation method ) 是由 王超哲 吴文兵 程康 李立辰 杨晓燕 董砺威 杨宇哲 王雪萦 席睿辰 于 2020-11-19 设计创作，主要内容包括：本发明提供一种套筒式多阶砂雨装置,包括支架,以及从上至下依次设置在支架上的第一阶筛筒、第二阶筛筒和第三阶筛筒,第一阶筛筒包括第一钢筒和第一筛网,第一钢筒固定在第一筛网上方,第一筛网外圈设有若干圆弧型滑槽,各滑槽分别可活动套设在相应的螺纹支撑杆上,第一筛网下方设有筛网挡片和圆环形的承重座圈,筛网挡片上下表面分别贴紧第一筛网下表面和承重座圈上表面,第二阶筛筒包括第二钢筒和第二筛网,第二钢筒固定在第二筛网上方,第三阶筛筒包括第三钢筒和第三筛网,第三钢筒固定在第三筛网上方。本发明的有益效果：采用全分布式雨砂,避免了移动路径和移动速度对砂样的影响,增强了砂样的整体均匀性和试验的可重复性。(The invention provides a sleeve type multistage sand rain device which comprises a support, a first order screen cylinder, a second order screen cylinder and a third order screen cylinder, wherein the first order screen cylinder, the second order screen cylinder and the third order screen cylinder are sequentially arranged on the support from top to bottom, the first order screen cylinder comprises a first steel cylinder and a first screen, the first steel cylinder is fixed above the first screen, a plurality of arc-shaped sliding grooves are formed in the outer ring of the first screen, each sliding groove is movably sleeved on a corresponding threaded supporting rod, a screen blocking piece and an annular bearing seat ring are arranged below the first screen, the upper surface and the lower surface of the screen blocking piece are tightly attached to the lower surface and the upper surface of the bearing seat ring respectively, the second order screen cylinder comprises a second steel cylinder and a second screen, the second steel cylinder is fixed above the second screen, the third order screen cylinder comprises a third steel cylinder and a third screen, and the third. The invention has the beneficial effects that: the fully distributed rain sand is adopted, so that the influence of a moving path and a moving speed on the sand sample is avoided, and the integral uniformity and the test repeatability of the sand sample are enhanced.)

1. A telescopic multistage sand rain device which is characterized in that: comprises a bracket, a first order sieve cylinder, a second order sieve cylinder and a third order sieve cylinder which are sequentially arranged on the bracket at intervals from top to bottom, wherein the bracket comprises a plurality of thread support rods which are vertically and uniformly arranged, the first order sieve cylinder comprises a first steel cylinder and a first screen, the outer diameter of the first steel cylinder is smaller than the outer diameter of the first screen, and the first steel cylinder is fixed above the first screen, a plurality of arc chutes are uniformly arranged on the periphery of the outer ring of the first screen, each chute is respectively movably sleeved on the corresponding thread support rod, a screen retaining piece and a circular bearing seat ring are arranged below the first screen, the screen retaining piece and the bearing seat ring are both arranged on the bracket, the upper surface and the lower surface of the screen retaining piece are respectively tightly attached to the lower surface of the first screen and the upper surface of the bearing seat ring, and a plurality of leak holes are uniformly arranged in the, the second order sieve section of thick bamboo includes a second steel cylinder and a second screen cloth, a second steel cylinder is fixed second screen cloth top, just each is located to second screen cloth periphery cover the screw thread bracing piece middle part, a third order sieve section of thick bamboo includes a third steel cylinder and a third screen cloth, a third steel cylinder is fixed third screen cloth top, just each is located to third screen cloth periphery cover the screw thread bracing piece bottom.

2. A telescopic multi-stage sand rain apparatus as claimed in claim 1, wherein: the gantry crane comprises a gantry frame and a hoist crane, wherein the support is positioned in the gantry frame, and the support is arranged below the gantry frame through the hoist crane.

3. A telescopic multi-stage sand rain apparatus as claimed in claim 2, wherein: a model cylinder for collecting sand samples is arranged under the third-order screen cylinder, and a plurality of calibration boxes are arranged in the model cylinder.

4. A telescopic multi-stage sand rain apparatus as claimed in claim 2, wherein: a plurality of lifting holes are formed in the upper portion of the first steel cylinder, and the first sieve cylinder is suspended on the portal frame through the lifting holes.

5. A telescopic multi-stage sand rain apparatus as claimed in claim 1, wherein: the inner diameter of the leak hole on the screen separation blade is the same as the inner diameter of the sieve hole on the first screen, the inner diameter of the sieve hole on the first screen is larger than the inner diameter of the sieve hole on the second screen, and the inner diameter of the sieve hole on the second screen is larger than the inner diameter of the sieve hole on the third screen.

6. A telescopic multi-stage sand rain apparatus as claimed in claim 3, wherein: levels are arranged on the first screen, the second screen and the third screen.

7. A telescopic multi-stage sand rain apparatus as claimed in claim 6, wherein: and a lifting lug is arranged at the bottom of the third-order screen drum, and a height measuring heavy hammer is suspended on the lifting lug.

8. A telescopic multi-stage sand rain apparatus as claimed in claim 2, wherein: and the bottom of the portal frame is provided with a caster.

9. A method of preparing a sand sample using the sleeve-type multistage sand rain device according to claim 7, comprising the steps of:

s1, mounting the first sieve cylinder, the second sieve cylinder and the third sieve cylinder on the bracket, adjusting the parameters of the sand rain device, including setting the fall distance length of the height measuring weight and setting the space between the second sieve cylinder and the first sieve cylinder as well as the third sieve cylinder, and making the screen separation piece block the screen hole of the first screen, and then filling the first sieve cylinder with test sand;

s2, hoisting the support to a preset drop distance position above the model cylinder through the hoist crane integrally, and leveling the first sieve cylinder, the second sieve cylinder and the third sieve cylinder through the levels respectively;

s3, adjusting the screen hole overlapping degree of the leak hole and the first screen on the screen baffle by rotating the first screen cylinder, so that the test sand falls out of the leak hole, and falls into the calibration box in the model cylinder through the second-stage screen cylinder and the third-stage screen cylinder in sequence, and simultaneously lifting the bracket synchronously through the hoist crane, so that the lower end position of the height measuring heavy hammer is always flush with the sand surface of the model cylinder;

s4, when the sand samples in the calibration boxes are collected, rotating the first sieve drum to enable the screen blocking piece to block the sieve hole of the first sieve, and measuring the compactness of the sand samples in the calibration boxes by using a miniature static penetrometer;

s5, repeating the steps S1-S4 for multiple times to obtain the corresponding relation between the sand sample compactness and each parameter of the sand rain device;

s6, manufacturing a sand sample with the compactness required by the test, and if the sand sample with the compactness required by the test is in the corresponding relation range of the step S5, preparing the sand sample according to corresponding parameters; otherwise, adjusting corresponding parameters of the sand rain device according to the corresponding relation obtained in the step S5 to prepare a sand sample required by the test, and then measuring the compactness of the prepared sand sample by adopting a miniature static penetrometer to check the accuracy of the prepared sand sample.

Technical Field

The invention relates to the technical field of sand sample preparation, in particular to a sleeve type multistage sand rain device and a sand sample preparation method.

Background

The model test is an important way for analyzing geotechnical engineering problems, wherein the model foundation sample preparation is a precondition for developing the model test. Taking sand sample preparation as an example, heavy hammer tamping or direct dumping is mostly adopted in the traditional methods, and although the methods are convenient and rapid, subjective influence factors are large, so that the uniformity of the sand sample cannot be ensured, and the sand sample can be repeatedly prepared, thereby influencing the analysis of subsequent test results. The sand rain method is one of sample preparation methods commonly used for preparing non-cohesive soil in the field of geotechnical engineering at present, the basic principle is that the sand particles are rearranged and distributed by utilizing the conversion of gravitational potential energy and kinetic potential energy between the sand particles and the mutual impact of the sand particles in the natural falling process, so that the sand sample has better uniformity and stable relative compactness, and meanwhile, the sand rain parameters such as the falling distance, the shape of a sand outlet, the size of the sand outlet, the total flow of the sand outlet, the moving path, the moving speed and the like are controlled, so that the sand sample with the same property can be ensured to be repeatedly prepared, and reliable basis is provided for the analysis of subsequent test data.

The prior sand rain sample preparation device can be divided into a dynamic sand rain device and a static sand rain device according to different sample preparation methods, and the prior sand rain device still has the following defects due to the difference of the sand sample preparation methods:

1) most of the existing dynamic sand rain devices have sand outlets with total area far smaller than that of a model box, and the moving path needs to be researched and designed, for example: lihao et al (geotechnical engineering journal, 2014, 36 (10): 1872-1878) have designed sand rain device with path guide, can carry on the rain sand along the predetermined path; zhao and Li Shi Yang (people Changjiang river 2015,46 (13): 73-77) designs a sand rain device capable of controlling the moving speed, path and other parameters of a sand outlet. However, the device inevitably introduces the influence of moving speed and path, and the speed in the moving process is not easy to control, so that the integral uniformity and repeatability of the sand sample are difficult to ensure;

2) existing static devices are for example: the sand rain device for geotechnical engineering model test (CN201310151463), the sand rain device for preparing geotechnical centrifugal model test and the preparation method thereof (CN201710103081) only have a single-layer sand outlet in the device, cannot ensure sufficient impact and collision among sand particles, and has insufficient sand sample distribution uniformity;

3) the existing static device has too rough flow control on a sand outlet, so that the falling energy of a sand sample cannot be well controlled, and the preparation of the sand samples with different compactness is difficult to realize.

Disclosure of Invention

In view of this, the embodiment of the invention provides a sleeve type multi-stage sand rain device and a sand sample preparation method.

The embodiment of the invention provides a sleeve type multistage sand rain device, which comprises a bracket, a first stage screen cylinder, a second stage screen cylinder and a third stage screen cylinder, wherein the first stage screen cylinder, the second stage screen cylinder and the third stage screen cylinder are sequentially arranged on the bracket at intervals from top to bottom, the bracket comprises a plurality of threaded support rods which are vertically and uniformly arranged, the first stage screen cylinder comprises a first steel cylinder and a first screen, the outer diameter of the first steel cylinder is smaller than the outer diameter of the first screen and is fixed above the first screen, a plurality of arc-shaped chutes are uniformly arranged on the periphery of the outer ring of the first screen, each chute is respectively movably sleeved on the corresponding threaded support rod, a screen baffle and an annular bearing seat ring are arranged below the first screen, the baffle and the bearing seat ring are both arranged on the bracket, the upper surface and the lower surface of the screen baffle are respectively attached to the lower surface of the first screen and the upper, and its middle part evenly is equipped with a plurality of small openings, a second order sieve section of thick bamboo includes a second steel cylinder and a second screen cloth, the second steel cylinder is fixed second screen cloth top, just each is located to second screen cloth periphery cover the screw thread bracing piece middle part, a third order sieve section of thick bamboo includes a third steel cylinder and a third screen cloth, the third steel cylinder is fixed third screen cloth top, just each is located to third screen cloth periphery cover the screw thread bracing piece bottom.

Furthermore, the gantry crane comprises a gantry frame and a hoist crane, wherein the support is positioned in the gantry frame and is arranged below the gantry frame through the hoist crane.

Further, a model cylinder for collecting sand samples is arranged under the third sieve cylinder, and a plurality of calibration boxes are arranged in the model cylinder.

Furthermore, a plurality of lifting holes are formed above the first steel cylinder, and the first sieve cylinder is suspended on the portal frame through the lifting holes.

Furthermore, the inner diameter of the leak hole in the screen separation blade is the same as the inner diameter of the sieve hole in the first screen, the inner diameter of the sieve hole in the first screen is larger than the inner diameter of the sieve hole in the second screen, and the inner diameter of the sieve hole in the second screen is larger than the inner diameter of the sieve hole in the third screen.

Furthermore, levels are arranged on the first screen, the second screen and the third screen.

Furthermore, a lifting lug is arranged at the bottom of the third order screen drum, and a height measuring heavy hammer is suspended on the lifting lug.

Furthermore, the bottom of the portal frame is provided with a caster.

The invention also provides a sand sample preparation method, which comprises the following steps:

s1, mounting the first sieve cylinder, the second sieve cylinder and the third sieve cylinder on the bracket, adjusting the parameters of the sand rain device, including setting the fall distance length of the height measuring weight and setting the space between the second sieve cylinder and the first sieve cylinder as well as the third sieve cylinder, and making the screen separation piece block the screen hole of the first screen, and then filling the first sieve cylinder with test sand;

s2, hoisting the support to a preset drop distance position above the model cylinder through the hoist crane integrally, and leveling the first sieve cylinder, the second sieve cylinder and the third sieve cylinder through the levels respectively;

s3, adjusting the screen hole overlapping degree of the leak hole and the first screen on the screen baffle by rotating the first screen cylinder, so that the test sand falls out of the leak hole, and falls into the calibration box in the model cylinder through the second-stage screen cylinder and the third-stage screen cylinder in sequence, and simultaneously lifting the bracket synchronously through the hoist crane, so that the lower end position of the height measuring heavy hammer is always flush with the sand surface of the model cylinder;

s4, when the sand samples in the calibration boxes are collected, rotating the first sieve drum to enable the screen blocking piece to block the sieve hole of the first sieve, and measuring the compactness of the sand samples in the calibration boxes by using a miniature static penetrometer;

s5, repeating the steps S1-S4 for multiple times to obtain the corresponding relation between the sand sample compactness and each parameter of the sand rain device;

s6, manufacturing a sand sample with the compactness required by the test, and if the sand sample with the compactness required by the test is in the corresponding relation range of the step S5, preparing the sand sample according to corresponding parameters; otherwise, adjusting corresponding parameters of the sand rain device according to the corresponding relation obtained in the step S5 to prepare a sand sample required by the test, and then measuring the compactness of the prepared sand sample by adopting a miniature static penetrometer to check the accuracy of the prepared sand sample.

The technical scheme provided by the embodiment of the invention has the following beneficial effects:

1) the fully distributed rain sand is adopted, so that the influence of a moving path and a moving speed on the sand sample is avoided, and the integral uniformity of the sand sample and the repeatability of a test are enhanced;

2) the structure that the size of the sieve pores of the third order is reduced progressively enables full impact and collision among sand particles, and sand samples are distributed more uniformly after sand grains are rearranged, so that certain compactness is obtained, and good sand sample quality is guaranteed;

3) the first-stage screen cylinder is provided with a sliding groove, the screen retaining sheet with the same aperture is arranged below the first-stage screen cylinder, the overlapping degree of the screen holes of the first-stage screen cylinder and the first-stage screen cylinder can be adjusted to control the flow of the sand outlet, and the method has the advantages of exquisite design, low cost, stability, durability and strong realizability.

Drawings

FIG. 1 is a schematic structural view of a sleeve type multi-stage sand rain device according to the present invention.

Fig. 2 is a schematic structural view of the bracket 1 and the third-order screen drum in fig. 1.

Fig. 3 is a schematic view of the structure of the first stage 2, screen dam 5 and load-bearing seat 6 of fig. 1.

In the figure: 1-bracket, 11-threaded support rod, 2-first sieve drum, 21-first steel drum, 22-first screen, 23-chute, 24-hanging hole, 3-second sieve drum, 31-second steel drum, 32-second screen, 4-third sieve drum, 41-third steel drum, 42-third screen, 43-lifting lug, 44-height measuring hammer, 5-screen baffle, 51-leakage hole, 6-bearing seat ring, 7-portal frame, 71-gourd crane, 72-caster, 8-model drum, 81-calibration box and 9-level.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be further described with reference to the accompanying drawings.

Referring to fig. 1, an embodiment of the present invention provides a sleeve type multistage sand rain device, which includes a bracket 1, a portal frame 7, and a first stage screen drum 2, a second stage screen drum 3, and a third stage screen drum 4, which are sequentially arranged on the bracket 1 at intervals from top to bottom.

The support 1 comprises a plurality of vertical and uniform threaded support rods 11, each threaded support rod 11 is located on the same circumference, in the embodiment, the support 1 is located in the portal frame 7 and is hung below the portal frame 1 through a hoist crane 71, and preferably, the bottom of the portal frame 7 is provided with a caster 72, so that the portal frame 7 can move conveniently.

Referring to fig. 2 and 3, the first stage screen drum 2 includes a first steel drum 21 and a first screen 22, the outer diameter of the first steel drum 21 is smaller than the outer diameter of the first screen 22 and is fixed above the first screen 22, a plurality of circular arc chutes 23 are uniformly arranged around the outer ring of the first screen 22, each chute 23 is movably sleeved on the corresponding threaded support rod 11, a screen baffle 5 and an annular bearing seat 6 are arranged below the first screen 22, the screen baffle 5 and the bearing seat 6 are both mounted on the bracket 1, the upper and lower surfaces of the screen baffle 5 are respectively attached to the lower surface of the first screen 22 and the upper surface of the bearing seat 6, and a plurality of leak holes 51 are uniformly arranged in the middle of the screen baffle 5, a plurality of hanging holes 24 are arranged above the first steel drum 21, and the first stage screen drum 2 is suspended on the portal frame 7 through the hanging holes 24, thereby facilitating rotation of the first cascade drum 2 to adjust the overlap of the mesh in the first screen 22 with the weep hole 51 in the screen catch 5.

Second order sieve section of thick bamboo 3 includes second steel cylinder 31 and second screen cloth 32, second steel cylinder 31 is fixed second screen cloth 32 top, just each is located to second screen cloth 32 periphery cover the 11 middle parts of screw thread bracing piece, third order sieve section of thick bamboo 4 includes third steel cylinder 41 and third screen cloth 42, third steel cylinder 41 is fixed third screen cloth 42 top, just each is located to third screen cloth 42 periphery cover the 11 bottoms of screw thread bracing piece.

Preferably, the inner diameter of the weep holes 51 on the screen separation blade 5 is the same as the inner diameter of the sieve holes on the first screen 22, the inner diameter of the sieve holes on the first screen 22 is larger than the inner diameter of the sieve holes on the second screen 32, and the inner diameter of the sieve holes on the second screen 32 is larger than the inner diameter of the sieve holes on the third screen 42, so that through a structure that the sizes of the sieve holes on the third screen are sequentially decreased, the sand particles are fully impacted and collided, sand particles are distributed more uniformly after being rearranged, and the quality of the sand sample is ensured.

According to the sand sample leveling device, a model cylinder 8 for collecting sand samples is arranged under a third-order screen cylinder 4, a plurality of calibration boxes 81 are arranged in the model cylinder 8, the calibration boxes 81 are used for collecting sand samples, leveling devices 9 are arranged on a first screen 22, a second screen 32 and a third screen 42, and each leveling device 9 is used for leveling the first screen 22, the second screen 32 and the third screen 42 respectively. In this embodiment, a lifting lug 43 is further disposed at the bottom of the third sieve drum 4, and a height measuring weight 44 is suspended on the lifting lug 43, so that the falling distance of the sand sample, i.e. the distance from the third sieve screen 42 to the sand surface, can be set by setting the length of the height measuring weight 44, so as to be used as a distance reference for keeping the falling distance.

The invention also provides a sand sample preparation method, which comprises the following steps:

s1, mounting the first stage screen cylinder 2, the second stage screen cylinder 3 and the third stage screen cylinder 4 on the bracket 1, adjusting the parameters of the sand rain device, including setting the fall distance length of the height measuring weight 44, setting the distance between the second stage screen cylinder 3 and the first stage screen cylinder 2 as well as the distance between the third stage screen cylinder 4, blocking the screen hole of the first screen 22 by the screen blocking piece 5, and then filling the first stage screen cylinder 2 with test sand, wherein the test sand is Fujian standard sand (the water content is about 0.11%) in an air-dry state, and the maximum dry density d of the standard sand is obtained according to GB/T50123-1999 geotechnical test method Standard_max＝1.633g/cm³Minimum dry density d_min＝1.337g/cm³Specific gravity of sand G_s＝2.633。

And S2, integrally hoisting the support 1 to a preset drop distance position above the model cylinder 8 through the hoist crane 71, and leveling the first sieve cylinder 2, the second sieve cylinder 3 and the third sieve cylinder 4 respectively through the levels 9.

S3, adjusting the overlapping degree of the sieve holes of the leakage hole 51 and the first sieve mesh 22 on the sieve mesh separation blade 5 by rotating the first sieve cylinder 2, so that the test sand falls out from the leakage hole 51 and sequentially falls into the calibration box 81 in the model cylinder 8 through the second-order sieve cylinder 3 and the third sieve cylinder 4, and simultaneously, the bracket 1 is synchronously lifted by the hoist crane 71, so that the lower end of the height measuring weight 44 is always flush with the sand surface of the model cylinder 8.

And S4, after the sand samples in the calibration boxes 81 are collected, rotating the first stage screen drum 2 to enable the screen separation sheet 5 to block the screen holes of the first screen 22, and measuring the compactness of the sand samples in the calibration boxes 81 by using a miniature static penetrometer.

S5, repeating steps S1-S4 for a plurality of times to obtain a corresponding relationship between the sand sample compactness and each parameter of the sand rain device, in this embodiment, the corresponding relationship between the sand sample compactness and each parameter of the sand rain device can be studied through the following experiments:

1) relation test of falling distance and sand sample compactness

Setting the fall distances L to be 0.4m, 0.6m and 0.8m respectively, keeping the distances between the second cascade screen cylinder 3 and the first cascade screen cylinder 2 as well as the third cascade screen cylinder 4 unchanged, and performing three-group parallel tests, wherein the compactness is D_rThe test results are as follows:

TABLE 1 relationship between different drop distances and sand sample compactness

Group of	L/m of falling distance	Degree of compactness Dr
			First group	0.4	Dr1
Second group	0.6	Dr2
			Third group	0.8	Dr3

2) Test of relationship between screen cylinder spacing and sand sample compactness of each stage

Respectively setting the space S between the second order screen drum 3 and the first order screen drum 2 and the third order screen drum 4 to be 0.2m and 0.5m, simultaneously keeping the falling distance unchanged, and performing two groups of parallel tests, wherein the relative compactness is D_r', test results are as follows:

TABLE 2 statistics of relationship between different screen drum spacings and sand sample compactness

Group of	The interval between every two screen cylinders is S/m	Relative compactness Dr'
			First group	0.2	Dr1′
Second group	0.5	Dr2′

In the above examples, only a few experiments are performed on the relationship between the sand sample compactness and different fall distances and screen drum distances, and in the actual operation process, the experiment times are further increased and verified for many times to obtain a more complete and accurate corresponding relationship library of the sand sample compactness and each parameter of the sand rain device; meanwhile, the corresponding relation between the sand sample compactness and other parameters such as a three-order screen cylinder combination mode and screen mesh coincidence degree can be further tested, so that the corresponding relation between the sand sample compactness and each parameter of the sand rain device is more complete.

S6, manufacturing a sand sample with the compactness required by the test, and if the sand sample with the compactness required by the test is in the corresponding relation range of the step S5, preparing the sand sample according to corresponding parameters; otherwise, adjusting corresponding parameters of the sand rain device according to the corresponding relation obtained in the step S5 to prepare a sand sample required by the test, and then measuring the compactness of the prepared sand sample by adopting a miniature static penetrometer to check the accuracy of the prepared sand sample.

In this document, the terms front, back, upper and lower are used to define the components in the drawings and the positions of the components relative to each other, and are used for clarity and convenience of the technical solution. It is to be understood that the use of the directional terms should not be taken to limit the scope of the claims.

The features of the embodiments and embodiments described herein above may be combined with each other without conflict.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.