A method for measuring the density of aeolian sand layers

Abstract

The application discloses a kind of aeolian sand layered density measurement methods, steps are as follows: a top open water tank is arranged in advance, connect multiple connecting pipes at the bottom of water tank, each connecting pipe is vertically provided with pressure measuring tube, water tank has floating plate floating on water surface, and floating plate is fixed with sand container; after floating plate and sand container float up and stabilize, the initial height of water column in pressure measuring tube is recorded; aeolian sand layer with thickness d is added in sand container in batches, the change value of water column height Δh in pressure measuring tube is recorded, and the mass, volume and density of the layer aeolian sand under Δh height change are calculated;Repeat the above steps, assume that aeolian sand is n layers, when the total thickness of aeolian sand layer reaches D, the final mass m of sand layer of total thickness D of aeolian sand layer is calculated total , total density ρ total ; finally, the layered density of each aeolian sand is obtained by recursive calculation.The application aims to provide a kind of layered density measurement method capable of measuring the layered density of each layer of aeolian sand.

Description

Technical Field

[0001] This invention relates to the field of aeolian sand measurement technology, and in particular to a method for measuring the density of aeolian sand layers. Background Technology

[0002] Aeolian sand is a layer of sand deposited by wind. In permafrost regions, desertification leads to the massive accumulation of aeolian sand on the surface, sometimes reaching several meters in thickness, altering the surface environment and severely impacting permafrost formation. However, the exact effects of aeolian sand on permafrost remain unclear. Different thicknesses of aeolian sand accumulation result in significant differences in heat conduction and moisture transfer, leading to varying impacts on the underlying permafrost. This is related to the density changes after aeolian sand accumulation. Due to pressure and other factors, the density of the bottom, middle, and top layers of aeolian sand varies, resulting in differences in the hydrothermal and other properties of each layer. Currently, there is a lack of methods to measure the density of each layer of aeolian sand after accumulation. Therefore, a method capable of measuring the density of each layer of aeolian sand is urgently needed. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and to provide a method for measuring the layer density of aeolian sand.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0005] A method for measuring the density of aeolian sand layers, comprising the following steps:

[0006] (1) A water tank (3) with an open top is arranged in advance. Multiple connecting pipes (2) are connected to the bottom of the water tank (3). Each connecting pipe (2) is vertically equipped with a pressure measuring pipe (1). The water tank (3) has a floating plate (5) floating on the water surface. A sand holding box (4) is fixed on the floating plate (5).

[0007] (2) Once the floating plate (5) and the sand tank (4) float up and stabilize, and the water column height in the pressure measuring tube (1) stabilizes, record the initial height of the water column in the pressure measuring tube (1);

[0008] (3) Add a layer of aeolian sand of thickness d to the sand container (4) in stages, and record the height of the water column in the piezometer (1). The change value, and calculate The specific steps for determining the mass, volume, and density of the aeolian sand layer under varying altitudes are as follows:

[0009] The floating plate (5) is forced downward by the gravity of the aeolian sand, pushing water into the connecting pipe (2) and then into the pressure measuring pipe (1). The pressure generated by the aeolian sand squeezing the water... Equivalent to the weight of water entering the pressure measuring tube (1):

[0010] (1)

[0011] in, The difference in water height in the pressure measuring tube (1) The cross-sectional area of ​​the pressure measuring tube (1) is... The density of water, For gravitational acceleration, the rise of the water column in the piezometer (1) is measured each time a layer of aeolian sand of thickness d is added. Corresponding to the increased pressure The mass of the newly added aeolian sand in the i-th iteration can be obtained. for:

[0012] (2)

[0013] in, Let the mass of the newly added aeolian sand in the i-th layer be , The change in the water column height in the piezometer (1) after the addition of the i-th layer of aeolian sand is given. After the i-th addition of aeolian sand, the total mass of the i-th layer of aeolian sand in the sand container (4) is:

[0014] (3)

[0015] in, Let be the mass of the k-th layer of aeolian sand, and be the volume of newly added aeolian sand in each layer. The following can be derived from the increased thickness d of this layer and the bottom area S of the sand container (4):

[0016] (4)

[0017] Accumulated up to the i-th layer, total volume for:

[0018] (5)

[0019] in, Let be the thickness of the k-th layer of aeolian sand, and the formula for calculating its density is: Substituting formulas (3) and (5) into the density calculation formula, the initial density of the i-th layer of aeolian sand can be obtained. for:

[0020] (6)

[0021] (4) Repeat step (3). Assuming there are n layers of aeolian sand, when the total thickness of the aeolian sand layers reaches D, calculate the final mass of the sand layer with a total thickness of D. Total density The specific steps are as follows:

[0022] When aeolian sand is added n times to reach the final total thickness D, the final mass of the aeolian sand at that thickness is... for:

[0023] (7)

[0024] Total density of sand layer The density formula and formula (7) can be used to calculate:

[0025] (8)

[0026] (5) The density of each aeolian sand layer is finally calculated recursively. Assuming that when the aeolian sand reaches the final total thickness D, the density of each layer increases with the compaction of the sand layer above. At this time, a recursive formula is defined to calculate the final compaction density of each layer from top to bottom. The density of the top layer remains unchanged, i.e. Starting from the top and working downwards, for each layer i below the top, based on the cumulative pressure of the layers above... By deducing its final compaction density, assuming the compaction relationship is:

[0027] (9)

[0028] in, It is the cumulative pressure borne by the i-th layer. To determine the compaction coefficient of aeolian sand, a suitable method is used to obtain the compaction coefficient. Then, the pressure of the i-th sand layer is calculated from the mass and gravity of the upper sand layer:

[0029] (10)

[0030] Starting recursively from the top nth layer, the final density of all i layers can be obtained as follows:

[0031] (11)

[0032] Furthermore, the compaction coefficient This can be obtained through a compaction test. In this test, a container is filled with aeolian sand, and the volume change of the sand is measured under different pressure conditions. Without applying external pressure, the initial volume of the aeolian sand is... The external pressure was gradually increased, and the volume of aeolian sand was measured at each pressure level. The pressure is considered to have reached its maximum value when the applied pressure no longer produces a significant change in volume. At this point, the compaction coefficient can be obtained using two fitting methods:

[0033] The first type is the experience index. Better adapted to the nonlinear behavior that occurs during the compaction process:

[0034] (12)

[0035] in, This refers to the applied external pressure. To facilitate fitting, a logarithmic transformation can be performed.

[0036] (13)

[0037] The second type is simple compaction coefficient. The fitting results show that there is a roughly linear relationship between density increment and pressure change. The compaction coefficient is obtained by using curve fitting. :

[0038] (14)

[0039] in, Due to the application of pressure The resulting density increase, i.e., the density change of aeolian sand, It is the initial density of aeolian sand before pressure is applied.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] This invention solves the technical challenge of measuring the stratification of aeolian sand on the surface of permafrost regions, enabling the determination of the stratified density of each layer. Based on the change in the height of the water column in the piezometer, the degree of pressure exerted by the aeolian sand on the water in the sand-holding chamber can be determined, thus inferring the mass of the sand. The experiment is relatively simple. Furthermore, it is unaffected by sand volume or deposition state. In practical experiments, water head pressure is the simplest and most reliable method for accurately determining the stratified density of each layer. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the pressure measuring tube and water tank in this invention;

[0043] Figure 2 for Figure 1 Top view.

[0044] Figure label:

[0045] 1-Pressure testing pipe, 2-Connecting pipe, 3-Water tank, 4-Sand tank, 5-Floating plate. Detailed Implementation

[0046] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] like Figure 1 and Figure 2 As shown, a method for measuring the density of aeolian sand layers includes the following steps:

[0048] (1) A water tank 3 with an open top is pre-arranged, and multiple connecting pipes 2 are connected to the bottom of the water tank 3. Each connecting pipe 2 is vertically equipped with a pressure measuring pipe 1. The water tank 3 has a floating plate 5 that floats on the water surface, and a sand holding box 4 is fixed on the floating plate 5. This method can obtain the density of each layer by adding aeolian sand layer by layer and measuring the change in water head pressure in the pressure measuring pipe 1. When the aeolian sand is loaded into the sand holding box 4 and placed in the water, the aeolian sand in the sand holding box 4 will exert pressure on the water, causing the water to be squeezed and flow to the pressure measuring pipe 1. By measuring the change in the height of the water column in the pressure measuring pipe 1, the degree of pressure of the aeolian sand on the water in the sand holding box 4 can be understood, and the mass of the sand can be inferred. The volume can be obtained by the increased sand layer thickness and the bottom area of ​​the sand holding box 4, and finally the layer density of the sand layer can be obtained.

[0049] (2) Once the floating plate 5 and the sand tank 4 are floating and stable, and the water column height in the pressure measuring tube 1 is stable, record the initial height of the water column in the pressure measuring tube 1.

[0050] (3) Add a layer of aeolian sand of thickness d to the sand container 4 in stages, and record the height of the water column in the piezometer 1. The change value, and calculate The mass, volume, and density of the aeolian sand layer under varying altitudes are determined. The specific method is as follows:

[0051] The floating plate 5 is forced downwards by the gravity of the aeolian sand, pushing water into the connecting pipe 2 and then into the pressure measuring pipe 1. The pressure generated by the aeolian sand squeezing the water... Equivalent to the weight of water entering pressure measuring tube 1:

[0052] (1)

[0053] in, The height difference of the water in pressure gauge 1 Let be the cross-sectional area of ​​pressure measuring tube 1. The density of water, Let gravitational acceleration be the acceleration due to gravity. The rise in water column in piezometer 1 is measured each time a layer of aeolian sand of thickness d is added. Corresponding to the increased pressure The mass of the newly added aeolian sand in the i-th iteration can be obtained. for:

[0054] (2)

[0055] in, Let the mass of the newly added aeolian sand in the i-th layer be , The change in water column height in piezometer 1 after the addition of the i-th layer of aeolian sand is given. The total mass of the i-th layer of aeolian sand in sand container 4 after the i-th addition of aeolian sand is:

[0056] (3)

[0057] in, Let be the mass of the k-th layer of aeolian sand, and be the volume of newly added aeolian sand in each layer. The following can be derived from the increased thickness d of this layer and the bottom area S of the sand container 4:

[0058] (4)

[0059] Accumulated up to the i-th layer, total volume for:

[0060] (5)

[0061] in, Let be the thickness of the k-th layer of aeolian sand, and the formula for calculating its density is: Substituting formulas (3) and (5) into the density calculation formula, the initial density of the i-th layer of aeolian sand can be obtained. for:

[0062] (6)

[0063] (4) Repeat step (3). Assuming there are n layers of aeolian sand, when the total thickness of the aeolian sand layers reaches D, calculate the final mass of the sand layer with a total thickness of D. Total density The specific method is as follows:

[0064] When aeolian sand is added n times to reach the final total thickness D, the final mass of the aeolian sand at that thickness is... for:

[0065] (7)

[0066] Total density of sand layer The density formula and formula (7) can be used to calculate:

[0067] (8)

[0068] (5) The density of each aeolian sand layer is finally calculated recursively. The specific method is as follows:

[0069] Assuming that when the aeolian sand reaches its final total thickness D, the density of each layer increases with the compaction of the layers above. A recursive formula is then defined to calculate the final compaction density of each layer from top to bottom, with the density of the top layer remaining constant. Starting from the top and working downwards, for each layer i below the top, based on the cumulative pressure of the layers above... By deducing its final compaction density, assuming the compaction relationship is:

[0070] (9)

[0071] in, It is the cumulative pressure borne by the i-th layer. This represents the compaction coefficient of aeolian sand. The compaction coefficient reflects the degree of compression of aeolian sand under pressure from the upper layers. This can be obtained through a compaction test. In this test, a container is filled with aeolian sand, and the volume change of the sand is measured under different pressure conditions. Without applying external pressure, the initial volume of the aeolian sand is... The external pressure was gradually increased, and the volume of aeolian sand was measured at each pressure level. The pressure is considered to have reached its maximum value when the applied pressure no longer produces a significant change in volume. At this point, the compaction coefficient can be obtained using two fitting methods:

[0072] The first type is the experience index. Better adapted to the nonlinear behavior that occurs during the compaction process:

[0073] (12)

[0074] in, This refers to the applied external pressure. To facilitate fitting, a logarithmic transformation can be performed.

[0075] (13)

[0076] Experience Index It can more accurately fit actual experimental data, especially under high pressure, and has stronger adaptability.

[0077] The second type is simple compaction coefficient. The fitting results show that there is a roughly linear relationship between density increment and pressure change. The compaction coefficient was obtained by using curve fitting based on experimental data. :

[0078] (14)

[0079] in, Due to the application of pressure The resulting density increase, i.e., the density change of aeolian sand, It is the initial density of aeolian sand before pressure is applied.

[0080] The simple compaction coefficient fitting calculation and operation are more convenient and suitable for situations with small density changes.

[0081] After obtaining the compaction coefficient using a suitable method, the sand pressure of the i-th layer is calculated from the mass and gravity of the upper sand layer:

[0082] (10)

[0083] Starting recursively from the top nth layer, the final density of all i layers can be obtained as follows:

[0084] (11)

[0085] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for measuring the density of aeolian sand layers, characterized in that: The steps are as follows: (1) A water tank (3) with an open top is arranged in advance. Multiple connecting pipes (2) are connected to the bottom of the water tank (3). Each connecting pipe (2) is vertically equipped with a pressure measuring pipe (1). The water tank (3) has a floating plate (5) floating on the water surface. A sand holding box (4) is fixed on the floating plate (5). (2) Once the floating plate (5) and the sand tank (4) float up and stabilize, and the water column height in the pressure measuring tube (1) stabilizes, record the initial height of the water column in the pressure measuring tube (1); (3) Add a layer of aeolian sand of thickness d to the sand container (4) in stages, and record the height of the water column in the piezometer (1). The change value, and calculate The specific steps for determining the mass, volume, and density of the aeolian sand layer under varying altitudes are as follows: The floating plate (5) is forced downward by the gravity of the aeolian sand, pushing water into the connecting pipe (2) and then into the pressure measuring pipe (1). The pressure generated by the aeolian sand squeezing the water... Equivalent to the weight of water entering the pressure measuring tube (1): （1） in, The difference in water height in the pressure measuring tube (1) The cross-sectional area of ​​the pressure measuring tube (1) is... The density of water, For gravitational acceleration, the rise of the water column in the piezometer (1) is measured each time a layer of aeolian sand of thickness d is added. Corresponding to the increased pressure The mass of the newly added aeolian sand in the i-th iteration can be obtained. for: （2） in, Let the mass of the newly added aeolian sand in the i-th layer be , The change in the water column height in the piezometer (1) after the addition of the i-th layer of aeolian sand is given. After the i-th addition of aeolian sand, the total mass of the i-th layer of aeolian sand in the sand container (4) is: （3） in, Let be the mass of the k-th layer of aeolian sand, and be the volume of newly added aeolian sand in each layer. The following can be derived from the increased thickness d of this layer and the bottom area S of the sand container (4): （4） Accumulated up to the i-th layer, total volume for: （5） in, Let be the thickness of the k-th layer of aeolian sand, and the formula for calculating its density is: Substituting formulas (3) and (5) into the density calculation formula, the initial density of the i-th layer of aeolian sand can be obtained. for: （6） (4) Repeat step (3). Assuming there are n layers of aeolian sand, when the total thickness of the aeolian sand layers reaches D, calculate the final mass of the sand layer with a total thickness of D. Total density The specific steps are as follows: When aeolian sand is added n times to reach the final total thickness D, the final mass of the aeolian sand at that thickness is... for: （7） Total density of sand layer The density formula and formula (7) can be used to calculate: （8） (5) The density of each aeolian sand layer is finally calculated recursively. Assuming that when the aeolian sand reaches the final total thickness D, the density of each layer increases with the compaction of the sand layer above. At this time, a recursive formula is defined to calculate the final compaction density of each layer from top to bottom. The density of the top layer remains unchanged, i.e. Starting from the top and working downwards, for each layer i below the top, based on the cumulative pressure of the layers above... By deducing its final compaction density, assuming the compaction relationship is: （9） in, It is the cumulative pressure borne by the i-th layer. To determine the compaction coefficient of aeolian sand, a suitable method is used to obtain the compaction coefficient. Then, the pressure of the i-th sand layer is calculated from the mass and gravity of the upper sand layer: （10） Starting recursively from the top nth layer, the final density of all i layers can be obtained as follows: （11）。 2. The method for measuring the density of aeolian sand layers according to claim 1, characterized in that: Compaction coefficient This can be obtained through a compaction test. In this test, a container is filled with aeolian sand, and the volume change of the sand is measured under different pressure conditions. Without applying external pressure, the initial volume of the aeolian sand is... The external pressure was gradually increased, and the volume of aeolian sand was measured at each pressure level. The pressure is considered to have reached its maximum value when the applied pressure no longer produces a significant change in volume. At this point, the compaction coefficient can be obtained using two fitting methods: The first type is the experience index. Better adapted to the nonlinear behavior that occurs during the compaction process: （12） in, This refers to the applied external pressure. To facilitate fitting, a logarithmic transformation can be performed. （13） The second type is simple compaction coefficient. The fitting results show that there is a roughly linear relationship between density increment and pressure change. The compaction coefficient is obtained by using curve fitting. : （14） in, Due to the application of pressure The resulting density increase, i.e., the density change of aeolian sand, It is the initial density of aeolian sand before pressure is applied.

Images