Sediment sampler and sampling and measuring method using the same

Abstract

The present application provides a sediment sampler and a sampling and measurement method using the sampler. The sampling tube portion is designed to be U-shaped, so that when sampling sediments with high water content and low shear strength, such as marine soft soil, the soil sample can naturally remain in the sampling tube, and there is no need to use a complex tube structure to prevent the soil sample from slipping out of the sampling tube; the U-shaped tube can provide stable air pressure at the tube ends during sampling, so that the interior of the soil sample will not be squeezed due to changes in the air pressure in the tube, thereby achieving high-precision pressure-maintaining sampling; the detachable design of the U-shaped tube avoids the weighing error introduced by the sampler's own weight, thereby greatly improving the accuracy of parameter measurement.

Description

Technical Field

[0001] The invention belongs to the field of geotechnical engineering, and particularly relates to a sediment sampler and a sampling and measuring method using the sampler. Background Art

[0002] In the past, land reclamation projects often used fill soil (or gravel) to fill landfill areas. However, with the severe shortage of sand for land reclamation, limited sand resources, and high cost, the use of in-situ soft soil in the ocean has become a common practice in many coastal cities. Because dredged soft soil has high water content, high compressibility, and low shear strength, the filling process should be carried out in stages, allowing the soil to settle and consolidate under its own weight to form new soil layers. Therefore, measuring the water content and density of soft soil used for fill can provide important information for optimizing land reclamation projects.

[0003] Currently, many sampling devices are designed for in-situ sampling to measure basic properties of soft sediments, such as water content and bulk density (or density). Commonly used samplers for soft sediments include fixed piston samplers, multi-samplers, or cylindrical samplers. Recently, a device has also emerged that can measure the real-time density of fluid silt. However, fluid silt density predictions require calibration for different types of soil and do not provide information on water content. Although water content and bulk density (or density) can be reverse-calculated when the specific gravity is known, accurately measuring specific gravity remains a challenge. Summary of the Invention

[0004] Based on this, the present invention proposes a sediment sampler and a sampling and measurement method using the sampler, which can be used to simultaneously measure the bulk density (or density) and water content of sediment to overcome the above-mentioned defects of the prior art.

[0005] In a first aspect, the present invention provides a sediment sampler comprising:

[0006] Active rod, sleeve, piston and U-tube;

[0007] A handle is provided at one end of the movable rod, and the end away from the handle is fixed to a piston provided at one end of the sleeve through a sleeve, so that when the movable rod moves along the sleeve in the sleeve, the piston is driven to move in the sleeve;

[0008] The first end of the U-shaped tube is removably mounted below the piston in the sleeve, and the second end is open during sampling. The openings at both ends of the U-shaped tube are equipped with sealing caps for sealing the openings at both ends when the U-shaped tube is removed to prevent the sediment from flowing out.

[0009] When the sampler is used for sampling, even force is applied to the handle of the movable rod, and the movable rod is pulled upward so that the sediment fills the U-shaped tube under the action of suction.

[0010] Furthermore, the sleeve is telescopic so that the length of the sleeve can be extended.

[0011] Furthermore, the movable rod is telescopic, so that the length of the portion of the movable rod within the sleeve can be extended.

[0012] Furthermore, the end of the movable rod away from the handle is an integrated structure with the piston.

[0013] Furthermore, the movable distance of the movable rod in the sleeve satisfies L≥V0 / A, where L represents the movable distance of the movable rod in the sleeve, V0 represents the volume of the U-shaped tube, and A represents the cross-sectional area of ​​the piston.

[0014] Furthermore, the U-shaped tube and the sleeve are made of tempered glass.

[0015] Furthermore, the U-shaped tube and the sleeve are made of metal.

[0016] In a second aspect, a sampling and measuring method using the sampler of the first aspect is provided, comprising:

[0017] Select a sampling site and insert the sampler into the sediment to the preset sampling depth;

[0018] Apply force evenly through the handle of the movable rod, pull up the movable rod to move the piston upward in the casing, and keep the casing still to generate suction, so that the U-shaped tube is filled with soil sample;

[0019] Take out the sampler slowly and steadily, remove the U-shaped tube and seal it with the sealing cap;

[0020] Determine the bulk density and / or moisture content of soil samples.

[0021] Furthermore, the determination of the bulk density of the soil sample includes:

[0022] Weigh the U-shaped tube filled with soil sample and calculate the bulk density of the soil sample according to the following formula:

[0023]

[0024] Where γ represents the bulk density of the soil sample, ρ represents the density, M1 represents the weight of the U-shaped tube after sealing when it is filled with soil sample, M0 represents the dead weight of the U-shaped tube and the sealing cover, V0 represents the volume of the U-shaped tube, and g represents the acceleration of gravity.

[0025] Furthermore, the above sampling and measurement method further includes:

[0026] Based on the measured bulk density and water content, the specific gravity of the soil sample is determined according to the following formula:

[0027]

[0028] Where Gs represents the specific gravity of the soil sample, γ represents the bulk density of the soil sample, and γ w represents the bulk density of water, and w represents the moisture content of the soil sample.

[0029] Furthermore, the moisture content of soil samples was determined by oven drying method.

[0030] Furthermore, before removing the U-shaped tube, the method further includes:

[0031] The handle of the movable rod is used to evenly apply force to push the movable rod, so that the remaining soil near the pipe opening of one end of the U-shaped pipe inserted into the sediment is pushed out of the U-shaped pipe under the thrust.

[0032] It can be seen from the above technical solutions that the present invention has the following beneficial effects:

[0033] The present invention proposes a sediment sampler and a sampling and measurement method using the sampler. The sampling tube part is designed to be U-shaped, so that when sampling sediments with high water content and low shear strength such as marine soft soil, the soil sample can naturally remain in the sampling tube, and there is no need to use a complex tube structure to prevent the soil sample from slipping out of the sampling tube; the U-shaped tube can provide stable air pressure at the tube ends during sampling, so that the interior of the soil sample will not be squeezed due to changes in air pressure in the tube, affecting the accuracy of soil sample measurement; the U-shaped tube storing the soil sample in the sampler can be removed and separated from the sampler for measurement, while conventional samplers usually need to separate the soil sample separately for measurement, and the weight of the sampler itself is usually several orders of magnitude different from the weight of the soil sample. The detachable structure of the present invention avoids this problem, can achieve high-precision pressure-maintaining sampling, and greatly improve the accuracy of bulk density (or density) measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the structure of the sediment sampler provided by the embodiment of the present invention

[0036] Figure 2 Schematic diagram of the sampling process of the sediment sampler provided by an embodiment of the present invention

[0037] Figure 3 Schematic diagram of sampling at the expected sampling depth provided by an embodiment of the present invention DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] The continuous development of marine resource development has led to the development of numerous projects using marine sediments as a carrier, especially land reclamation projects in coastal cities. Therefore, understanding the physical and mechanical properties of marine sediments is particularly important for the construction of marine engineering. Marine sediments, especially shallow sediments, are mainly saturated soft soils. This type of soil has a low bulk density, relatively low undrained shear strength and compressive strength, high water content, is saturated and loose, and is easily disturbed. Engineering indicators such as the mechanical properties of sediments are related to factors such as the stress conditions of the soil sample, the degree of disturbance, and the surrounding environmental conditions. Therefore, the original state of the sediments should be obtained as much as possible during the sampling process before the indicators are measured. Fidelity sampling of sediments usually has the following technical requirements: low disturbance of sample shape, pressure maintenance, heat preservation, no pollution, and no pressure drop post-processing.

[0040] Traditional marine sediment sampling equipment mostly uses cylindrical samplers. Due to the high water content and saturated, loose nature of marine sediments, using a piston-less sampler can easily disrupt the original soil sample sequence, causing mechanical disturbances such as bending, deformation, and shortening due to the weight of the soil sample and friction between the sampler and the sediment, thus destroying the original soil sample. To counteract friction and the weight of the soil sample, samplers either use complex anti-slip structures, which make the sampling device bulky and inconvenient to operate, or use piston-type structures, which are unsuitable for long samplers. Furthermore, traditional sampling equipment often requires separating the soil sample from the device for parameter measurement after sampling. This process can also easily destroy the original sediment state. If the sampling device filled with soil sample is measured as a whole, the weight of the device is often much greater than the weight of the soil sample, often comparing several kilograms to tens of grams. If using kilogram-level precision measuring instruments, the sample weighing error will be very large. Traditional sediment sampling equipment has not yet been able to directly and accurately measure sediment parameters.

[0041] The present invention proposes a structurally improved sediment sampler. By changing the structural shape of the sampling tube, it is possible to complete the faithful sampling of sediment without using a complex structure, and can accurately measure multiple parameters of the soil sample at one time without the need for repeated calculations, thereby reducing the errors caused by multiple mathematical operations and the extraction of soil samples.

[0042] like Figure 1As illustrated, the sediment sampler 100 provided by the embodiment of the present invention includes

[0043] Movable rod 1, sleeve 2, piston 3 and U-shaped tube 4;

[0044] A handle 11 is provided at one end of the movable rod 1, and the end away from the handle 11 is fixed to a piston 3 provided at one end of the sleeve 2 through the sleeve 2, so that when the movable rod 1 moves along the sleeve direction in the sleeve 2, the piston 3 is driven to move in the sleeve 2;

[0045] The first end of the U-shaped tube 4 is removably mounted below the piston 3 in the sleeve 2, and the second end is open during sampling. The openings at both ends of the U-shaped tube 4 are provided with sealing caps 41 for sealing the openings at both ends when the U-shaped tube 4 is removed to prevent the sediment from flowing out.

[0046] When the sampler 100 is used for sampling, uniform force is applied to the handle 11 of the movable rod 1, and the movable rod 1 is pulled upward so that the sediment fills the U-shaped tube through the second end of the U-shaped tube 4 under the action of suction.

[0047] The sampling tube of the sampler is designed to be U-shaped, allowing sediment to naturally remain within the tube upon entering the sampler. This obstruction is achieved simply by changing its shape, eliminating the need for complex structures to block flow. This not only reduces the complexity of the sampler's structure but also its manufacturing cost. The simple structure also makes it easier to operate. Furthermore, the straight sections on both sides of the U-shaped tube are of similar length, maintaining essentially the same air pressure on both sides. This ensures pressure-maintained sampling of sediment and reduces disturbances such as bending and shortening of the soil sample due to air pressure, which is crucial for accurate post-sampling parameter measurement. The removable U-shaped tube allows for more accurate measurement of sediment parameters such as bulk density, density, and water content without altering the original sediment state. The weight of the removed U-shaped tube is not significantly different from that of the soil sample. When technicians wish to directly weigh the entire sampling tube filled with soil sample, the tube's weight does not introduce significant weighing errors. For measurements of parameters such as bulk density and density, technicians do not need to remove the soil sample first, minimizing disturbance to the sample.

[0048] In some embodiments, the movable rod 1 and the sleeve 2 are designed to be retractable, so that the length of the sampler can be extended, which is suitable for samplers with large lengths and can achieve fidelity sampling of sediments in the deep ocean or even the bottom layer.

[0049] The movable rod and the piston can be made separately and then connected together for fixing. Fixing methods such as welding, gluing, pressing, casting, etc. are all allowed. The movable rod and the piston can also be an integrated structure, which is then nested with the sleeve after being integrated.

[0050] In some embodiments, the tube portion of the sampling tube includes a sleeve 2 and a U-shaped tube 4, which can be made of tempered glass or metal to obtain a thinner tube wall, reduce the impact of the sampling equipment itself on the measurement, and thereby improve the accuracy of parameter measurement.

[0051] like Figure 2 The sampling process shown in FIG. 1 includes the following steps:

[0052] Select a sampling site and insert the sampler 100 into the sediment to a preset sampling depth;

[0053] Apply force evenly through the handle 11 of the movable rod 1, pull up the movable rod 1 so that the piston 3 moves upward in the casing 2, while keeping the casing 2 stationary to generate suction, so that the U-shaped tube 4 is filled with soil sample;

[0054] Slowly and steadily remove the sampler 100, remove the U-shaped tube 4 and seal it with the sealing cap 41;

[0055] Determine the bulk density and / or moisture content of soil samples.

[0056] The volume V0 of the empty U-shaped tube has been pre-calibrated. The mass of the empty tube together with the two sealing caps is recorded as M0. After sampling and sealing, the mass of the U-shaped tube is weighed, and the mass when filled with soil sample is recorded as M1. Therefore, the bulk density of the soil sample can be expressed by formula (1):

[0057]

[0058] In the formula, γ represents the bulk density of the soil sample, ρ represents the density, and g represents the acceleration of gravity. It can be seen from the formula that the sediment sampler provided by the present invention can also be used to directly measure the density of the soil sample without removing the soil sample from the tube, which can ensure the accuracy of the measurement.

[0059] The moisture content w of the soil sample can be directly measured by the drying method.

[0060] For the soil samples obtained by sampling, the relationship between its bulk density γ and water content w can be expressed as formula (2):

[0061]

[0062] Where γ w Indicates the bulk density of water, G s represents the specific gravity of sediment, and e represents the porosity of soil sample.

[0063] The relationship between porosity e and water content w can be expressed as:

[0064]

[0065] Where S rIndicates the saturation of the soil sample. When the sediment is completely saturated, S r =1, combining equations (2) and (3) we can get the sediment specific gravity G s It is expressed as follows:

[0066]

[0067] It can be seen from formula (4) that the specific gravity of the soil sample can be calculated after the bulk density and water content of the sediment are measured. When the bulk density and water content are measured accurately, the specific gravity does not need to be measured again and can be determined using the calculation relationship.

[0068] It is worth mentioning that when inserting the sampler into the sediment, a small amount of sediment may enter the U-shaped tube, such as Figure 3 The situation shown, combined with Figure 2 After the sampler reaches the preset sampling depth, the piston 3 is pulled up a certain distance L by pulling up on the movable rod 1, while the U-tube 4 and the sleeve 2 remain stationary. Due to suction, the small amount of sediment that enters the U-tube during insertion is drawn into the sleeve, and the U-tube is filled with the soil sample obtained at the desired sampling depth. To ensure sufficient soil sampling, the piston stroke (L) × the piston cross-sectional area (A) must be ≥ the U-tube volume (V0).

[0069] When the sampler is pulled out from the sediment, some sediment may adhere to the mouth of the U-shaped tube. To ensure that the soil sample comes completely from the sediment layer at the required position / depth, after the sampler is pulled out, the handle 11 of the movable rod 1 is used to evenly push the movable rod 1, so that the remaining soil near the mouth of the U-shaped tube 4 is pushed out of the U-shaped tube under the action of the thrust.

[0070] In summary, the sediment sampler provided by the present invention utilizes a U-shaped sampling tube structure to form an anti-slip sampling space, so that the soil sample can remain in its original state in the sampler, and the structure is simple and easy to operate. The U-shaped tube can form a stable air pressure environment at the tube openings on both sides, reducing the mechanical disturbance of the soil sample by the air pressure in the tube. After the sampling is completed, the U-shaped tube can be removed and separated from the sampler body, and the engineering parameters such as the bulk density, density, and water content of the sediment can be measured at one time. There is no need to weigh the entire sampler or calculate the parameters with each other, which reduces the errors introduced by the sampler's own weight and mathematical operations, and greatly improves the accuracy of parameter measurement. The bulk density and water content of the sediment can be measured using the sampler of the present invention, and the specific gravity of the sediment can be directly calculated. The sleeve and the movable rod are designed to be retractable, which can extend the length of the sampler and is suitable for sampling of large lengths.

[0071] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some of the technical features thereof can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A sediment sampler, characterized in that: include: Active rod, sleeve, piston and U-tube; A handle is provided at one end of the movable rod, and an end away from the handle is fixed to the piston provided at one end of the sleeve through the sleeve, so that when the movable rod moves along the sleeve direction in the sleeve, it drives the piston to move in the sleeve; The first end of the U-shaped tube is removably sleeved below the piston in the sleeve, and the second end is in an open state during sampling. The openings at both ends of the U-shaped tube are equipped with sealing caps for sealing the openings at both ends when the U-shaped tube is removed to prevent the sediment from flowing out; The movable distance of the movable rod in the sleeve satisfies L≥V0 / A, where L represents the movable distance of the movable rod in the sleeve, V0 represents the volume of the U-shaped tube, and A represents the cross-sectional area of ​​the piston; When the sampler is used for sampling, uniform force is applied to the handle of the movable rod, and the movable rod is pulled up so that the sediment is filled and retained in the U-shaped tube under the action of suction, and the sampling and measurement of the sediment is achieved by measuring the U-shaped tube filled with and retaining the sediment.

2. The sediment sampler according to claim 1, characterized in that The sleeve is telescopic so that the length of the sleeve can be extended.

3. The sediment sampler according to claim 1, characterized in that The movable rod is telescopic so that the length of the portion of the movable rod within the sleeve can be extended.

4. The sediment sampler according to claim 1, characterized in that The end of the movable rod away from the handle is an integrated structure with the piston.

5. The sediment sampler according to claim 1, characterized in that The U-shaped tube and the sleeve are made of tempered glass.

6. The sediment sampler according to claim 1, characterized in that The U-shaped tube and the sleeve are made of metal.

7. A sampling and measuring method using the sediment sampler according to any one of claims 1 to 6, characterized in that: include: Select a sampling site and insert the sampler into the sediment to the preset sampling depth; Apply force evenly through the handle of the movable rod, pull up the movable rod to move the piston upward in the casing, and keep the casing stationary to generate suction, so that the U-shaped tube is filled with soil sample; Slowly and steadily remove the sampler, remove the U-shaped tube and seal it with a sealing cap; The bulk density and / or water content of the soil sample is determined by measuring the U-shaped tube in which the soil sample is sealed.

8. The sampling and measuring method according to claim 7, characterized in that: The determination of the bulk density of the soil sample includes: Weigh the U-shaped tube filled with soil sample and calculate the bulk density of the soil sample according to the following formula: Where γ represents the bulk density of the soil sample, ρ represents the density, M1 represents the weight of the U-shaped tube after sealing when it is filled with soil sample, M0 represents the dead weight of the U-shaped tube and the sealing cover, V0 represents the volume of the U-shaped tube, and g represents the acceleration of gravity.

9. The sampling and measuring method according to claim 7, characterized in that: The sampling and measuring method further comprises: Based on the measured bulk density and water content, the specific gravity of the soil sample is determined according to the following formula: Where G s represents the specific gravity of the soil sample, γ represents the bulk density of the soil sample, and γ w represents the bulk density of water, and w represents the moisture content of the soil sample.

10. The sampling and measuring method according to claim 7, characterized in that: The water content of the soil samples was determined by oven drying method.

11. The sampling and measuring method according to claim 7, characterized in that: Before removing the U-shaped tube, the method further comprises: The handle of the movable rod is used to uniformly apply force to push the movable rod, so that the remaining soil near the pipe opening of one end of the U-shaped tube inserted into the sediment is pushed out of the U-shaped tube under the action of the thrust.

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