Water bottom sample soil collecting device, and water bottom sample soil collecting method

Abstract

To provide a water bottom sample soil collecting device which can surely take sample soil in a sampling pipe without providing a marine scaffold by a spud barge or the like, and can surely recover the sample soil taken in the sampling pipe, in a case in which the sample soil is collected from a viscous earth ground of a water bottom or a modified soil earth ground obtained by mixing the viscous earth ground with a modified material.SOLUTION: A water bottom sample soil collecting device 1 has: a sampling pipe 3 for storing sample soil to be collected; a piston 5 provided in the sampling pipe 3; and a water filling pipe 19 provided in parallel with the sampling pipe 3. The piston 5 generates a negative pressure in the sampling pipe 3 in a process of penetrating the sampling pipe 3 into the ground, as a result, the sample soil is taken in the sampling pipe 3. The water filling pipe 19 fills water toward a lower end of the sample soil taken in the sampling pipe 3 when the sampling pipe 3 is pulled from the ground, and reduces pull-out force generated on the lower end of the sample soil.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a water bottom soil sampling device for sampling soil samples from a water bottom clayey soil layer or an improved soil layer obtained by mixing an improver with the clayey soil layer, and a water bottom soil sampling method using the same. [Background technology]

[0002] FIG. 1 of Patent Document 1 proposes a method for improving seabed ground made of clay soil using a ground improvement ship equipped with a waterbed ground improvement device.

[0003] In the seabed ground improvement work disclosed in Figure 1 of Patent Document 1, a submarine ground improvement device mounted on a work ship (ground improvement ship) is pressed into the seabed ground to take in the existing ground (clay soil) on the seabed into a casing, a predetermined amount of modifier is fed into the casing through a material supply line, and the existing ground and modifier in the casing are stirred and mixed with a stirring blade to produce modified soil. The modifier to be stirred and mixed with the existing ground is, for example, a material made from steel slag.

[0004] The modified soil thus produced inside the underwater casing is then backfilled in the original location of the existing ground, replacing the existing ground with the modified soil to create a modified soil ground, as shown in Figure 1(b) of Patent Document 1. By repeating this process of producing modified soil and backfilling at different positions on the seabed, the target ground is improved.

[0005] Patent Document 2 describes a device for collecting samples from modified soil ground, which does not require work by divers and can be easily collected from the sea using only a work vessel such as a crane ship. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-013447 A (Figure 1) [Patent Document 2] Utility model registration No. 3227316 Summary of the Invention [Problem to be solved by the invention]

[0007] In seabed ground improvement work, it is necessary to sample the seabed clayey soil to confirm the soil quality, etc. of the seabed clayey soil to be improved. In addition, after or during the seabed ground improvement work, it is necessary to sample the improved soil from the seabed to confirm the quality, such as the strength, of the improved soil after or during the ground improvement work.

[0008] When checking the quality of the improved soil after seabed ground improvement, such as its strength, a scaffolding on the sea is generally secured using a spud barge or the like, and the improved soil that has hardened after a curing period is sampled by core boring. On the other hand, when it is desired to visually check the mixing quality during construction, or when core boring after hardening would disturb the sample soil when sampling, a method is used in which the improved soil is sampled immediately after construction (before hardening).

[0009] When sampling improved soil immediately after construction, the sampling work needs to be done near the ground improvement ship, so a sampling method that requires securing an offshore scaffold using a spud barge or the like may cause interference between the ground improvement ship and the offshore scaffold, hindering the work of both parties. In that sense, the sampling device described in Patent Document 2 does not require an offshore scaffold, so it can be said to be a suitable method for sampling improved soil immediately after construction.

[0010] However, modified soil produced using existing ground consisting of seabed clay has the characteristic of having adhesive power even before hardening. Therefore, when a simple tubular sampler or the sampling pipe described in Patent Document 2 is simply driven into the seabed, the modified soil will enter the sampling pipe at the beginning of the pushing, but the resistance (friction and adhesion between the inner wall of the sampling pipe and the modified soil) gradually increases, and the modified soil will no longer enter the sampling pipe, which is a problem.

[0011] Furthermore, when the modified soil from the seabed is taken into the sampling tube and then pulled out, negative pressure is generated in the space where the sampling tube is pulled up, generating a pulling force that pulls the modified soil in the sampling tube downward. This pulling force that pulls the contents of the sampling tube downward becomes large if the sampled soil has adhesive properties. Therefore, when sampling modified soil ground that has been improved from clayey soil, simply driving the sampling tube into the seabed can cause a problem that even if the modified soil can be taken into the sampling tube, the modified soil in the sampling tube will escape when pulled out. The same problem occurs when sampling clayey soil ground on the seabed.

[0012] The method described in Patent Document 2 is based on the premise that the sampling pipe will be pulled out after the modified soil inside has hardened, and so sampling is possible simply by equipping the tip of the sampling pipe with a member to prevent it from coming out. However, when it is desired to visually check the mixed quality of the modified soil during construction, there is a problem in that the modified soil taken into the sampling pipe cannot be quickly retrieved without waiting for it to harden.

[0013] Furthermore, when sampling the seabed clayey soil to be improved, the use of the method described in Patent Document 2 was considered. However, the method in Patent Document 2 is based on the premise that the sampling tube will be removed after the improved soil to be sampled has hardened, and therefore has the problem that the clayey soil captured in the sampling tube cannot be recovered with the method in Patent Document 2.

[0014] In view of the above-mentioned problems, the object of the present invention is to provide a water bottom sample soil sampling device and a water bottom sample soil sampling method which, when sampling soil from clayey soil ground on the bottom of water, including the seabed, or from modified soil ground where a modifier has been mixed into the clayey soil ground, can reliably take in the sample soil (clayey soil or modified soil) into a sampling tube without setting up offshore scaffolding such as a spud barge, and which also makes it possible to reliably recover the sample soil (clayey soil or modified soil) taken into the sampling tube. [Means for solving the problem]

[0015] The above-mentioned object can be achieved by a water bottom sample soil collection device, which is an apparatus for collecting sample soil from a clayey soil ground at the bottom of the water or from a modified soil ground which has been mixed with a modifying material, comprising a collection tube for containing the sample soil to be collected, a piston provided inside the collection tube for taking the sample soil into the collection tube, and a pull-out force reduction means for injecting water or supplying air toward the lower end of the collection tube to reduce the pull-out force generated at the lower end of the sample soil taken into the collection tube, and which is characterized in that the sample soil is taken into the collection tube without changing the depth with the piston in close contact with the top of the ground.

[0016] The pull-out force reducing means of the bottom soil sampling device is, for example, a water injection pipe. In this case, the water injection pipe has a water intake port located underwater above the top of the ground when the sampling pipe is inserted into the ground, and a water injection port located near the bottom end of the sampling pipe when the sampling pipe is inserted into the ground.

[0017] Furthermore, when the above-mentioned pull-out force reduction means is constituted by the water injection pipe, the water injection pipe has a sample soil intrusion prevention valve at the lower end of the water injection pipe for preventing the sample soil from intruding into the water injection port.

[0018] The water bottom soil sampling device further includes a fall prevention member for preventing the soil sample taken into the sampling tube from falling.

[0019] The water bottom soil sampling device further includes a weight for applying a penetrating force to the sampling tube, and / or a vibration excitation device for applying a penetrating force to the sampling tube.

[0020] The above object can also be achieved by a method for collecting soil samples from the bottom of the water using the above-mentioned water-bottom soil collecting device, in which, with a piston positioned at the lower end within a collection tube, the collection tube is set on the top surface of the ground at the bottom of the water, the collection tube is inserted into the ground while maintaining the depth of the piston, and the sample soil is taken into the collection tube, and when removing the collection tube with the sample soil inside, water or air is injected toward the lower end of the collection tube so as to reduce the pulling force generated at the lower end of the sample soil taken inside the collection tube while removing the collection tube, thereby collecting the sample soil. Effect of the Invention

[0021] The piston provided in the bottom soil sampling device maintains the state in which the bottom end of the sampling tube is in close contact with the top surface of the ground (the top surface of the soil to be sampled) without changing the depth of the sampling tube during the process of penetrating the ground. This allows negative pressure to be generated in the sampling tube during the process of penetrating the ground, making it possible to take the sample soil inside the sampling tube by using the negative pressure. In addition, the pulling force reduction means provided in the bottom soil sampling device plays a role in injecting water or supplying air toward the bottom end of the sampling tube when the sampling tube is pulled out from the bottom ground, thereby filling the space where the sampling tube is pulled up with water or air. This reduces the pulling force generated at the bottom end of the soil taken into the sampling tube, making it possible to recover the sample soil taken into the sampling tube without it falling out when the sampling tube is pulled out.

[0022] In addition, by using a water injection pipe as the pull-out force reduction means, which is made up of a water intake port located underwater above the top of the ground and a water injection port located near the bottom of the sampling pipe, the negative pressure generated in the space where the sampling pipe is pulled up is transmitted through the water injection pipe to the water intake port located underwater, and the water above the top of the ground is sucked in and injected into the bottom of the water sampling pipe. This makes it possible to inject water simply and reliably without using a water conveying means such as a pump.

[0023] In addition, by providing a sample soil intrusion prevention valve that prevents sample soil from entering the water inlet, the water injection pipe will not become clogged with sample soil during the process of penetrating the sampling pipe into the ground, and the function of the water injection pipe as a pull-out force reduction means can be maintained.

[0024] Furthermore, by providing the bottom soil sampling device with a fall prevention member, it is possible to prevent the soil samples from falling out of the sampling tube due to their own weight when the sampling tube is being pulled out of the ground.

[0025] In addition, by providing the bottom soil sample collection device with at least one of a weight for applying a penetration force to the collection tube and a vibration device for applying a penetration force to the collection tube, when the sample soil collection device is inserted into the ground at the bottom of the water, the collection tube can be reliably inserted against buoyancy and penetration resistance. [Brief description of the drawings]

[0026] [Figure 1] 1 is a side view showing a bottom soil sampling device according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the general configuration of the water bottom soil sample collecting device shown in FIG. [Diagram 3] 2 is a process diagram showing a method for collecting water bottom soil samples using the water bottom soil sample collecting device shown in FIG. 1. [Figure 4] A cross-sectional view showing the function and operation of a piston equipped in the water bottom soil sample collecting device. [Diagram 5] 4 is a cross-sectional view showing the function and action of a water injection pipe (pulling force reduction means) provided on the water bottom soil sample collection device. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] The water bottom soil sampling device according to the present invention is a device for sampling soil samples (soil samples) from the water bottom, and is mounted on, for example, a ground improvement ship or a work ship equipped with a crane and a lifting device. Specific examples of sample soil sampled by the water bottom soil sampling device include clay soil from the sea bottom and modified soil produced by mixing and stirring this with a modifier. The modifier mixed and stirred into the sea bottom clay soil is, for example, a material made from steel slag.

[0028] The configuration of the water bottom soil sampling device will be described below with reference to Figures 1 and 2. In this application, specific examples of the "bottom" include the bottom of the ocean, the bottom of a river, and the bottom of a lake. In the following description of the present invention, the bottom of the ocean will be used as an example of the bottom of the ocean.

[0029] (Water bottom soil sampling device) As shown in FIG. 1 and FIG. 2, the water bottom soil sampling device 1 is A sampling tube 3 for containing the sample soil to be collected; A piston 5 that is vertically movable within the sampling tube 3; A piston rod 7 having a piston 5 fixed to its lower end; A sampling tube support rod 13 that supports the sampling tube 3; A weight 15 and a vibration device 17 provided on the sampling tube support rod 13; A water injection pipe 19 is used to inject water toward the bottom of the sample soil taken into the sampling pipe 3. It has.

[0030] The sampling pipe 3 is a tubular member for sampling soil samples from the seabed, and has an open upper end and an open lower end. In this embodiment, the sampling pipe 3 is composed of a tubular sampling pipe body 4 and a cylindrical lower cap 9 attached to its lower part. During the process of penetrating the sampling pipe 3 into the seabed ground, the seabed soil samples are taken into the sampling pipe body 4 (the area below the piston 5) through the inside of the cylindrical lower cap 9.

[0031] As shown on the left in Figure 2, a ring-shaped connecting part 21 protrudes from the top of the lower cap 9, and a thread is formed on its outer periphery. By screwing the connecting part 21 of the lower cap 9 into the bottom of the collection tube body 4, the two are connected and integrated. The collection tube body 4 and lower cap 9 integrated together function as the collection tube 3.

[0032] Inside the lower cap 9, a drop prevention member 23 is provided to prevent the sample soil taken into the sampling tube 3 from falling under its own weight. In this embodiment, the drop prevention member 23 is made of a check valve and is attached via a pin 25 so that it can rotate freely within a predetermined angle range starting from the pin 25. In Figures 1 and 2, the drop prevention member 23 is shown in an open state by a solid line. In this state, the sample soil to be collected passes through the inside of the lower cap 9 and is taken into the sampling tube 3. In Figures 1 and 2, the drop prevention member 23 is shown in a closed state by a dashed line. In this state, the drop prevention member 23 blocks the inner opening of the lower cap 9, so that the sample soil to be collected cannot come out of the sampling tube 3.

[0033] In this embodiment, a check valve is used as the fall prevention member 23 provided on the lower cap 9, but the fall prevention member can also be formed of a protrusion provided so as to protrude from the inner peripheral surface of the lower cap 9. The bottom of the soil sample taken into the sampling tube 3 is caught on the protrusion (fall prevention member), thereby preventing the soil sample from falling.

[0034] An upper cap 31 is integrally provided at the bottom of the sampling tube support rod 13, which is attached to the top of the sampling tube 3. A thread is formed on the inner peripheral surface of the upper cap 31, and the two are joined by screwing the top of the sampling tube 3 into the inside of the upper cap 31. As shown in Figure 1, a hoisting device 33 is provided at the top of the sampling tube support rod 13. A chain or the like is connected to the hoisting device 33, and the sampling tube support rod 33 is hoisted using the facilities of the work boat.

[0035] As shown in Fig. 1, the upper cap 31 is provided with a fluid inlet / outlet 35. This fluid inlet / outlet 35 functions as an inlet / outlet for air and seawater that allows the air in the sampling tube 3 to be replaced with seawater when the sampling tube 3 is lowered from the sea surface to the seabed. By replacing the air in the sampling tube 3 (the area above the piston 5) with seawater through the fluid inlet / outlet 35 of the upper cap 31, buoyancy in water is suppressed, and it becomes possible to maintain the attitude of the sampling tube 3 vertically in water. Furthermore, the fluid inlet / outlet 35 of the upper cap 31 functions as a seawater outlet that allows seawater in the sampling tube 3 to be discharged to the outside of the sampling tube as the piston 5 rises relatively inside the sampling tube 3 due to the penetration of the sampling tube 3 into the ground. By discharging seawater inside the sampling tube 3 (the area above the piston 5) to the outside of the sampling tube through the fluid inlet / outlet 35 of the upper cap 31, the piston 5 can rise relatively inside the sampling tube 3, thereby generating a negative pressure for taking in the sample soil into the sampling tube 3. The fluid inlet / outlet 35 of the upper cap 31 also functions as an air inlet that allows air to enter the sampling tube 3 when the piston 5 pushes out and recovers the soil sample in the sampling tube 3. When the piston 5 pushes out the soil sample, air enters the sampling tube 3 (the area above the piston 5) from the fluid inlet / outlet 35 of the upper cap 31, allowing the soil sample in the sampling tube 3 to be smoothly pushed out and recovered. It is preferable that two fluid inlets / outlets 35 are provided at positions opposite each other in the circumferential direction, and three or more fluid inlets / outlets 35 may be provided at approximately equal intervals in the circumferential direction.

[0036] A piston rod 7 is inserted inside the sampling tube support rod 13 , and the piston rod 7 can freely move up and down inside the sampling tube support rod 13 .

[0037] The weight 15 is a weight fixed to the outer periphery of the sampling tube support rod 13. This weight 15 not only serves to apply a penetration force to the sampling tube 3, but also serves to keep the sampling tube 3 vertical against buoyancy from the sea surface until it reaches the seabed.

[0038] The vibration exciter 17 is, for example, a vibrating hammer, and is fixed to the outer periphery of the sampling tube support rod 13. This vibration exciter 17 serves to apply a penetrating force to the sampling tube 3. In this embodiment, the water bottom soil sample sampling device 1 is equipped with both the weight 15 and the vibration exciter 17, but it may be configured to include only one of them.

[0039] The piston rod 7 is provided so as to be freely insertable through the sampling tube support rod 13, which is the outer tube, and the inside of the upper cap 31, and the piston 5 in the sampling tube 3 is fixed to its lower end.

[0040] The piston 5 is provided so as to be able to move up and down within the sampling tube body 4. This piston 5 plays a role in generating negative pressure within the sampling tube body 4 when the sampling tube 3 is inserted, thereby taking in the seabed soil samples into the sampling tube 3, and also plays a role in pushing out and discharging the soil samples taken into the sampling tube 3 when the collected soil samples are visually inspected.

[0041] 1, a hoisting device 6 is provided on the upper part of the piston rod 7. A chain or the like is connected to the hoisting device 6, and the piston rod 7 is suspended using the facilities of the work boat.

[0042] The piston 5, which is integrally provided at the lower end of the piston rod 7, can move up and down within the sampling pipe body 4. When the sampling of the bottom soil sample begins, the piston 5 is positioned at the lower end within the sampling pipe 3. When positioning the piston 5, the piston rod 7 is manually pushed down to position the piston 5 at its tip at a predetermined position within the sampling pipe 3. When the sampling pipe 3 penetrates the ground, as shown in Fig. 4 (1) to (3) in order, the piston 5 remains in close contact with the seabed surface (the top surface of the sample soil to be sampled). At this time, the chain or the like connected to the hoisting device 6 of the piston rod 7 is fixed without being unwound. Therefore, the piston 5 does not push down the seabed surface together with the sampling pipe 3 and is not buried in the ground. In other words, by penetrating the sampling pipe 3, which is integral with the sampling pipe support rod 13, into the ground, the piston 5 rises relatively within the sampling pipe 3 while in close contact with the seabed surface. During the process of penetrating the sampling pipe 3 into the ground, the piston 5 remains seemingly stationary without changing its depth as shown in Figs. 4(1) to (3).

[0043] The water injection pipe 19, which is the pulling force reducing means, is made of, for example, a PVC pipe or a water hose, and is fixed to the outer circumferential surface of the sampling pipe 3 and arranged in parallel as shown in FIG. 1. The water injection pipe 19 has a water intake port 41 that is located underwater during the process of penetrating the sampling pipe 3 into the ground, and a water injection port 43 that is located near the bottom end of the sampling pipe. The water intake port 41 of the water injection pipe 19 is located underwater above the top of the ground when the sampling pipe 3 is penetrated into the ground, and the water injection port 43 is located near the bottom end of the sampling pipe 3. The water injection port 43 is provided with a sample soil intrusion prevention valve that prevents sample soil from entering and clogging the water injection pipe 19 during the process of penetrating the sampling pipe 3 into the ground. The sample soil intrusion prevention valve is made of, for example, a check valve attached to close the water injection port 43.

[0044] This water injection pipe 19 injects water taken into the water injection pipe 19 from the water intake port 41 toward the lower end of the sampling tube 3 from the water injection port 43 due to the negative pressure generated when the sampling tube 3 is pulled out of the ground, thereby reducing the pulling force generated at the lower end of the sample soil taken into the sampling tube 3.

[0045] In this embodiment, the water injection tube 19 is used as the pulling force reducing means, but it is also possible to use an air supply means for supplying compressed air, etc. In this case, instead of the water injection tube 19, the pulling force reducing means can be configured with, for example, an air compressor that generates compressed air, or an air hose that supplies compressed air toward the lower end of the sampling tube.

[0046] (Method of collecting water bottom soil samples) Next, a method for collecting water-bottom soil samples using the water-bottom soil sampling device 1 described above will be described mainly with reference to Figures 3 to 5. Note that steps a to e described below correspond to Figures 3(a) to (e). In the following, a concrete example of sample soil to be collected using the water-bottom soil sampling device 1 will be taken as existing seabed ground made of clay soil.

[0047] Process a First, the piston 5 of the bottom soil sample collection device 1 is set at the lower end of the sampling pipe 3 (the lower end of the sampling pipe body 4). Next, the bottom soil sample collection device 1 is hung from the ship toward the seabed from which the sample is to be collected, and the lower end of the sampling pipe 3 is abutted against the top surface of the seabed (the top of the sample soil to be collected) while the sampling pipe 3 is kept vertical. When the bottom soil sample collection device 1 is hung, the whole device 1 is hung toward the seabed via a chain connected to the hanging tools 6, 33 of the bottom soil sample collection device 1. It is also possible to install a current meter on the sampling pipe support rod 13 or the sampling pipe 3, and hang the device so that it is in a vertical position while checking the value of the current meter.

[0048] As the sampling tube 3 of the water bottom soil sampling device 1 descends underwater, the air inside the sampling tube 3 (the area above the piston 5) is replaced with seawater through the fluid inlet / outlet 35 of the upper cap 31, suppressing buoyancy in the water and keeping the sampling tube 3 vertical in the water. The weight 15 also counters buoyancy to cause the sampling tube 3 to sink to the seabed.

[0049] Process b Next, the sampling pipe 3 that has landed on the seabed in a vertical position is penetrated into the seabed ground. When penetrating the sampling pipe 3, a vibration generator 17 consisting of a vibro hammer or the like is operated to apply a driving force (penetration force) to the tip of the sampling pipe 3. The sampling pipe 3 receives the driving force from the vibration generator 17 and the weight of the weight 15 and starts to penetrate into the ground.

[0050] During the process of penetrating the sampling pipe 3, as shown in Fig. 4 (1) to (3) in order, the piston 5 remains stationary without changing the depth while in close contact with the seabed surface (the top surface of the sample soil to be collected). Meanwhile, the sampling pipe 3 integrated with the sampling pipe support rod 13 continues to penetrate into the ground. Therefore, during the process of penetrating the sampling pipe 3, the piston 5 rises relatively upward from the lower end inside the sampling pipe 3 while in close contact with the seabed surface (the top surface of the sample soil to be collected).

[0051] During the process of penetrating the sampling pipe 3, the chain etc. connected to the suspending tool 6 of the piston rod 7 is fixed without being paid out so that the piston 5 remains in contact with the seabed surface and seemingly stationary without changing the depth. Meanwhile, the chain etc. connected to the suspending tool 33 of the sampling pipe support rod 13 is not fixed and is paid out in accordance with the penetration so that the sampling pipe 3 integrated with the sampling pipe support rod 13 can be lowered.

[0052] During the penetration of the sampling tube 3, friction and adhesion occur between the inner surface of the sampling tube 3 and the soil sample that has been taken in. However, at the beginning of the penetration, these friction and adhesion are small, so that the soil sample passes through the inside of the lower cap 9 and is taken into the sampling tube 3 as it penetrates. At this time, the fall prevention member 23 is pushed in by the soil sample being taken in, and maintains a standing state on the inner surface side of the sampling tube 3 as shown by the solid lines in Figures 1 and 2. As the penetration progresses, the friction and adhesion occurring between the inner surface of the sampling tube 3 and the soil sample that has been taken in increases, preventing the soil sample from being taken in, and eventually the soil sample that is being taken in tries to drop down while integrated with the sampling tube 3.

[0053] However, in this embodiment, the piston 5 remains stationary without changing its depth while in close contact with the seabed surface (the top surface of the sample soil to be collected), and rises relatively upward from the lower end of the sampling tube 3. Therefore, the rise of the piston 5 generates negative pressure inside the sampling tube 3. This negative pressure acts as a suction force, pulling up the sample soil that is being taken in but is trying to go down together with the sampling tube 3 inside the sampling tube 3. Therefore, even if the frictional force and adhesive force increase as the penetration of the sampling tube 3 progresses, the sample soil can be reliably drawn into the sampling tube 3 against the frictional force and adhesive force.

[0054] Furthermore, seawater flowing in through the fluid inlet / outlet 35 of the upper cap 31 does not flow below the piston 5 when the sampling tube 3 is inserted.

[0055] Process c When the bottom end of the sampling tube 3 reaches the target depth, the above-mentioned penetration of the sampling tube 3 is completed, and the vibration excitation device 17 is stopped. When penetration is completed, the inside of the sampling tube 3 is filled with the collected sample soil from just below the piston 5 to the bottom end of the sampling tube 3. The sample soil collected in the sampling tube 3 maintains almost the same state as it was in the ground before it was collected.

[0056] Process d Next, start to pull out the sampling pipe 3. During the pulling process, the chains connected to the hoisting devices 6, 33 of the water bottom soil sampling device 1 are simultaneously wound up, and the entire water bottom soil sampling device 1 (i.e., the sampling pipe 3 and the piston 5 together) is simultaneously pulled up, as shown in Figure 4 (4).

[0057] When the bottom soil sampling device 1 is pulled up, negative pressure is generated under the piston 5 which pulls up the sampling tube 3 together with the sampling tube 3, and friction and adhesion are generated between the inner wall of the sampling tube 3 and the soil sample. Therefore, when the bottom soil sampling device 1 is pulled up, a force is generated to pull up the soil sample in the sampling tube 3 (i.e., a force that pulls the soil sample in the sampling tube 3 together with the sampling tube 3), and a force acts at the bottom end of the sampling tube 3 to separate the soil sample taken in from the clayey soil layer below. On the other hand, negative pressure is generated in the space where the sampling tube 3 is pulled out (i.e., directly below the removed sampling tube 3), so a force is generated to pull the soil sample taken in the sampling tube 3 downward when the sampling tube 3 is pulled out. If the force that pulls up the soil sample in the sampling tube 3 when the bottom soil sampling device 1 is pulled up is smaller than the force that pulls the soil sample downward due to the negative pressure generated in the space where the sampling tube is pulled out, the soil sample taken in may come out of the sampling tube 3. Alternatively, the soil sample in the sampling tube 3 may break apart midway, making it impossible to recover the entire amount of soil sample taken into the sampling tube 3.

[0058] However, in this embodiment, the water injection pipe 19 is provided in parallel with the sampling pipe 3. As shown in FIG. 5, the water injection pipe 19 has a water injection port 43 at the lower end located near the lower end of the sampling pipe 3, and a water intake port 41 at the upper end located underwater above the seabed. When the sampling pipe 3 and the piston 5 are pulled up, as shown in FIG. 5, seawater is automatically injected into the space directly below the sampling pipe 3 through the water injection pipe 19 due to the negative pressure generated in the space, and the space is instantly filled with seawater. Therefore, the negative pressure generated in the space directly below the sampling pipe 3 (the force pulling the sample soil in the sampling pipe 3 downward) is suppressed by the seawater instantly injected into the space, and as a result, the pulling force generated when the sampling pipe 3 is pulled up is reduced.

[0059] Thereafter, in the process of pulling up the sampling tube 3 toward the sea, even if the sample soil taken in the sampling tube 3 tries to fall, as the sample soil falls, it pushes the fall prevention member 23 in the lower cap 9 in the closing direction shown by the dashed line in Figures 1 and 2, closing the lower end opening of the sampling tube 3, so that the sample soil is caught by the fall prevention member 23 and prevented from falling out of the sampling tube. Therefore, the sample soil taken in during the process of pulling out the sampling tube 3 can be reliably collected without falling out of the sampling tube during the pulling up process.

[0060] Process e The water bottom soil sampling device 1 is continued to be pulled up, the sampling pipe 3 is pulled out from the seabed, and then pulled out from the sea, completing the sampling of the soil samples.

[0061] When recovering sample soil from the sampling tube 3 of the bottom soil sampling device 1 that has been pulled up from the sea, the lower cap 9 at the lower end of the sampling tube 3 is removed, and the piston 5 is pushed down via the piston rod 7 to push the sample soil out of the sampling tube body 4 and recover it.

[0062] Finally, the above-mentioned embodiment is an example of the present invention described in the claims, and the present invention is not necessarily limited thereto. The application of the present invention is not limited to the collection of existing ground made of clay on the bottom of the water or modified soil after ground improvement, but can also be used to collect soil samples of alternating layers of sand and clay or modified soil made by mixing dredged clay with a modifying material. In addition, the site where the present invention can be used is not limited to the bottom of the sea, but can also be used on the bottom of a river or lake. [Explanation of symbols]

[0063] 1. Water bottom soil sample collection device (soil sample collection device) 3 Collection tube 4 Collection tube body 5 Piston 6. Lifting equipment 7 Piston rod 9 Bottom Cap 13 Sampling tube support rod 15 Weight 17 Excitation device 19 Water injection pipe (means for reducing pull-out force) 21 Joint 23 Fall prevention parts 25-pin 31 Top Cap 33 Lifting equipment 35 Fluid inlet / outlet 41 Water intake 43 Water inlet 91 Work boat (ground improvement boat) 92 Underwater soil improvement equipment 93 Casing 94 Material supply pipe 95 Stirring blade

Claims

1. This is a device for collecting sample soil from clayey soil at the bottom of a body of water or from modified soil made by mixing the clayey soil with a modifying material. A sampling tube for containing the sample soil to be collected; a piston provided inside the sampling tube for introducing the soil sample into the sampling tube; and a pull-out force reducing means for injecting water or air toward the lower end of the sampling tube to reduce the pull-out force generated at the lower end of the sample soil taken into the sampling tube, The sample soil is taken into the sampling tube without changing the depth with the piston in close contact with the top of the ground. A water bottom soil sampling device characterized by the above.

2. The pull-out force reducing means is A water inlet located underwater above the top of the ground with the sampling pipe penetrated into the ground; A water inlet located near a lower end of the sampling pipe in a state where the sampling pipe is inserted into the ground; 2. The apparatus for collecting soil samples from the bottom of a body of water according to claim 1, characterized in that it is composed of a water injection pipe having a water injection pipe.

3. 3. The apparatus for collecting soil samples from the bottom of water according to claim 2, wherein the water injection pipe has a soil sample intrusion prevention valve at the lower end of the water injection pipe for preventing the soil sample from intruding into the water injection port.

4. 4. The apparatus for collecting soil samples from the bottom of water according to claim 1, further comprising a fall prevention member for preventing the soil samples taken into the sampling tube from falling.

5. The soil sample sampling device further includes a weight for applying a penetrating force to the sampling tube, and / or a vibration device for applying a penetrating force to the sampling tube.

4. An apparatus for collecting soil samples from the bottom of water as claimed in claim 1.

6. A method for collecting soil samples from the bottom of a body of water using the apparatus for collecting soil samples from the bottom of a body of water according to claim 1, With the piston positioned at the bottom of the sampling tube, set the sampling tube on the top surface of the ground at the bottom of the water. While maintaining the depth of the piston, the sampling pipe is inserted into the ground, and the sample soil is taken into the sampling pipe. When the sampling tube with the sample soil taken in is pulled out, water or air is poured toward the lower end of the sampling tube to reduce the pulling force generated at the lower end of the sample soil taken in the inside of the sampling tube, and the sampling tube is pulled out. Collecting the sample soil; A method for collecting soil samples from the bottom of water.

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