JP2014169533A - Soil sampling tube and boring method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a soil sampling tube preventing boiling to be generated when a core tube is pulled out after boring, in a method for performing boring and soil sampling by pushing a cylindrical casing into a subgrade by its vibration and its own weight and storing a soil sample in the core tube set inside the casing; and a boring method for the soil sampling tube.SOLUTION: A soil sampling tube comprises: a cylindrical casing 1; and a core tube 2 having a beating shoe 3 at its tip. An outer peripheral engaging part 32 having a diameter reducing toward its tip side coming into contact with an inner peripheral engaging part 12 of the casing 1 and continuing in the circumferential direction is formed on an outer peripheral surface of the beating shoe 3. A vertical groove 4a traversing the outer peripheral engaging part 32 is formed in the beating shoe 3.

Description

  The present invention relates to a method for excavating a soil sampling pipe for investigating the ground in which a casing is dug into the ground by vibration and dead weight, and a soil sampling pipe used for the method.

  In recent years, for example, a ground investigation method using a boring device that performs liquefaction determination of a residential land of a detached house, investigation of a contamination state, and the like has been performed. The conventional boring device uses the boring device's own weight as a reaction force to rotate the excavator attached to the tip of the rod to cut and press-fit the ground, and circulate water and heavy mud water to bring the earth and sand to the ground. I was digging. For this reason, the excavation speed tended to depend on the skill of the operator. In addition, preparation of equipment for circulating water and heavy muddy water is necessary, which has a problem of poor work efficiency. As an improvement of this point, a vibro drill (VD) type boring device is known (Japanese Patent No. 5021104).

  The VD boring device is a vibro drill that pushes the casing into the ground with the vibration and its own weight and stores the soil sample in the core tube set inside the casing, enabling excavation and sampling. . In addition to high excavation capability, it is possible to collect soil samples simultaneously with excavation, and there is no need for preparation of equipment to circulate water and heavy mud water, and there is an advantage that work efficiency is higher than conventional boring .

Japanese Patent No. 5021104

  However, in excavation using the VD type boring device, when a certain depth is exceeded, a boiling phenomenon occurs in which sandy soil enters the casing together with groundwater when the core tube is pulled out after excavation. For this reason, there was a problem that it took time to remove the soil remaining in the casing. In addition, there is a problem that the standard penetration test cannot be performed because collapse of the hole bottom ground occurs due to boiling.

  Therefore, the object of the present invention is to push the casing into the ground by vibration and its own weight and store the soil sample in the core tube set inside the casing, thereby performing the excavation and sampling in the method of excavating and sampling the core tube. An object of the present invention is to provide a soil sampling pipe and a method for digging the soil sampling pipe that prevent the occurrence of boiling when pulling out the soil.

  That is, the present invention solves the above-described problem, and includes a cylindrical casing and a core tube having a driving shoe inserted into the casing at the tip, and an inner peripheral surface on the tip side of the casing. Is formed with an annular inner peripheral locking portion that is reduced in diameter toward the distal end side that locks the driving shoe and is continuous in the circumferential direction, and the inner peripheral locking portion is formed on the outer peripheral surface of the driving shoe. A soil sample characterized in that an outer peripheral locking portion that is reduced in diameter toward the leading end side that abuts and that is continuous in the circumferential direction is formed, and a groove that crosses the outer peripheral locking portion is formed in the driving shoe. A collection tube is provided.

  Further, the present invention provides the soil sample collection tube, wherein the groove is a vertical groove, and is formed at a plurality of positions at an appropriate pitch in one place or in the circumferential direction.

  Further, the present invention provides the soil sampling tube, wherein the longitudinal groove extends from the upper end of the driving shoe to the front end side beyond the front end of the casing. .

  Further, the present invention is a method of using the soil sampling tube to push the casing into the ground by vibration and dead weight, and to collect the soil sample in a core tube set inside the casing, Before or after setting the core tube inside the casing, water or muddy water is poured into the casing, and the casing and the core tube are driven by simultaneous driving. An object of the present invention is to provide a method for digging a soil sampling pipe, characterized in that a step of flowing muddy water is performed.

  Further, the present invention is a method of using the soil sample collection tube, pushing the casing into the ground by vibration and dead weight, and collecting the soil sample in the core tube set inside the casing, the casing and the core tube being A method for digging a soil sampling pipe, characterized in that when digging by simultaneous driving and pulling up the core tube, water or mud water is injected between the casing and the core tube and the water or mud water flows down from the groove. It is to provide.

  According to the present invention, when the core tube is pulled out after excavation, water or muddy water flows out from the longitudinal groove formed in the driving shoe. For this reason, the collected ground weight is replaced with water or muddy water, and the weight of the water or muddy water presses down the hole bottom ground to prevent the occurrence of boiling. Therefore, the subsequent standard penetration test can be continued without any problems.

It is a disassembled perspective view of the soil sampling pipe | tube in embodiment of this invention. It is a perspective view of the soil sampling pipe | tube in embodiment of this invention. It is a decomposition | disassembly expanded sectional view of the front-end | tip part of the soil sampling pipe | tube of this example. It is a front view of a driving shoe used in the soil sampling pipe of this example. Is a sectional view taken along the _X 1 -X ₁ line in FIG. Is a sectional view taken along the _X 2 -X ₂ line in FIG. 4. It is a front view of the other driving shoe used with the soil sampling pipe | tube of this example. Is a sectional view taken along the _X 3 -X ₃ line in FIG. 7. It is a figure explaining the excavation method of the soil sampling pipe | tube in embodiment of this invention. It is a process following FIG. 9, and is a diagram for explaining a method for digging a soil sampling pipe. It is a figure explaining the excavation method of the conventional soil sample collection pipe | tube. It is another figure explaining the conventional excavation method of the soil sample collection pipe.

  Next, the soil sample collection tube in the embodiment of the present invention will be described with reference to FIGS. The soil sample collection tube 10 includes a hollow cylindrical casing 1 and a core tube 2 having a driving shoe 3 inserted into the casing at the tip. Since the casing 1 is basically dug without water, it is used for the purpose of protecting the hole wall. The casing 1 is long and has a hollow main body 11 having the same diameter in the longitudinal direction, and a reduced diameter portion 13 having an inner diameter smaller than the inner diameter of the hollow main body 11 at the tip of the hollow main body 11. . For this reason, between the hollow main body part 11 and the reduced diameter part 13, an annular inner peripheral locking part 12 that is gradually reduced in diameter toward the distal end side and continuous in the circumferential direction is formed. That is, on the inner peripheral surface on the front end side of the casing 1, an annular inner peripheral engagement portion 12 that is gradually reduced in diameter toward the front end side and continuous in the circumferential direction is formed. The inner peripheral locking portion 12 has a function of closely contacting the outer peripheral locking portion 32 of the driving shoe 2 and locking the driving shoe 2 during driving. The opposite end side of the casing 1 has a connecting portion for addition. Reference numeral 14 denotes a hollow portion penetrating vertically.

  The core tube 2 is a long hollow tube inserted into the casing 1 and collects and stores soil. For this reason, the outer diameter of the core tube 2 is smaller than the inner diameter of the casing 1, and after the core tube 2 is inserted into the casing 1, a gap 6 is generated between the casing 1 and the core tube 2. A connecting rod 22 is formed on the opposite end side of the core tube 2. Further, a screw portion into which the driving shoe 3 is screwed is formed on the distal end side of the core tube 2. The core tube 2 may be in a half shape. Thereby, it is easy to take out the collected soil. The code | symbol 23 is a hollow part penetrated up and down.

  The driving shoe 3 is a short hollow tube, and is fixed to the tip of the core tube 2 by screwing or the like. A screw portion 34 that is screwed into the core tube 2 is formed on the opposite end side of the shoe main body portion 31, and a reduced diameter portion having an inner diameter smaller than the outer diameter of the shoe main body portion 31 is formed on the front end side of the shoe main body portion 31. 33 is formed. For this reason, an annular outer peripheral locking portion 32 is formed between the shoe main body portion 31 and the reduced diameter portion 33 and gradually decreases in diameter toward the distal end side and continues in the circumferential direction. The outer peripheral locking part 32 comes into close contact with the inner peripheral locking part 12 of the casing 1. Thereby, if the core tube 2 is driven in, the outer peripheral locking part 32 of the core tube 2 and the inner peripheral locking part 12 of the casing 1 are locked, and it is possible to dig together with the casing 1. Further, water or the like does not flow in a portion where the outer peripheral locking portion 32 and the inner peripheral locking portion 12 are in close contact with each other. Reference numeral 5 denotes a hollow portion penetrating vertically.

  The driving shoe 3 is formed with a groove crossing the outer peripheral locking portion 32, in this example, a vertical groove 4a. Since the outer peripheral locking portion 32 extends in the circumferential direction orthogonal to the longitudinal direction (digging direction) of the core tube, and the vertical groove 4a crosses this, the vertical groove (groove extending in the drilling direction) and It will be. Thereby, if water is poured into the gap 6 between the casing 1 and the core tube 2, the water will flow through the vertical groove 4a. That is, the vertical groove 4a is a flow path of water, and it only needs to have a width and a depth enough to flow under natural flow of water. In this example, it extends across the outer peripheral locking portion 32 from the upper end of the shoe main body portion 31 of the driving shoe 3 to the distal end side, and extends beyond the distal end of the reduced diameter portion 33. That is, when the core tube 2 is inserted into the casing 1, the longitudinal groove 4 a extends beyond the tip of the casing 1. That is, the longitudinal groove 4a only needs to cross the outer peripheral locking portion 32, and may extend to the tip side across the outer peripheral locking portion 32. A slight gap 7 is formed between the reduced diameter portion 33 of the driving shoe 3 and the casing 1. However, since the vertical groove 4 a is formed, the reduced diameter portion 33 of the driving shoe 3 and the casing 1 are also sufficient. A simple water flow path can be formed to promote the flow of water between the reduced diameter portion 33 and the casing 1 (see FIG. 9).

  In addition, the vertical groove 4a is not limited to the embodiment of FIGS. 4-6, For example, what is shown to FIG.7 and FIG.8 may be used. 7 and 8, the same components as those in FIGS. 4 to 6 are denoted by the same reference numerals, description thereof is omitted, and different points are mainly described. That is, the vertical groove 4b in FIGS. 7 and 8 is different from the vertical groove 4a in FIGS. 4 to 6 in the position of the lower end of the vertical groove. That is, the vertical groove 4 b extends from the upper end of the shoe main body 31 of the driving shoe 3 to the distal end side of the outer peripheral locking portion 32 and extends to the lower end of the outer peripheral locking portion 32. Unlike the longitudinal groove 4 a, it does not extend to the reduced diameter portion 33 of the driving shoe 3, but crosses the outer peripheral locking portion 32 and passes through a slight gap 7 between the reduced diameter portion 33 of the driving shoe 3 and the casing 1. Water can flow down.

  As shown in FIGS. 4 to 8, these longitudinal grooves 4a and 4b may be formed at two positions at intervals of 180 degrees in the circumferential direction. May be formed at four positions at intervals of 90 degrees. Among these, those formed at four positions at intervals of 90 degrees in the circumferential direction are preferable in that water can flow uniformly to the tip portion of the casing 1.

  Next, before explaining a method for digging a soil sampling pipe in the embodiment of the present invention, a conventional method for digging a soil sampling pipe will be described with reference to FIGS. 11 and 12. First, the casing 1 is built in the ground using a vibro drill (VD) type boring device (not shown). Since this method of excavating the soil sampling pipe is in principle waterless, the casing 1 is built for the purpose of protecting the hole wall. Next, the core tube 2 with the driving shoe 3 attached to the tip is inserted into the casing 1. At this time, the connecting rod 22 provided on the opposite end side of the core tube 2 is connected to the boring rod of the VD boring device. Thereby, the low frequency vibration which generate | occur | produces with a vibro motor is transmitted to the core tube 2 via the connecting rod 22, a frictional resistance can be reduced, and the core tube 2 can be driven into a formation. A soil sample can be collected and stored in the core tube 2 by driving into the formation. Next, only the core tube 2 is pulled up to the ground, and the soil sample in the core tube 2 is taken out. The first 1 m soil sample may be discarded. The casing 1 after the core tube 2 is pulled out is hollow. Next, a known standard penetration test is carried out (end of step I).

  Next, the core tube 2 that is empty inside is newly inserted into the casing 1. At this time, as shown in FIG. 11, the inner peripheral locking portion 12 of the casing 1 and the outer peripheral locking portion 32 of the core tube 2 are in close contact with each other, and low-frequency vibration is applied to the connecting rod 22 of the core tube 2. By giving, it becomes possible to dig along with the casing 1 by simultaneous driving from 1 m to 2 m. In addition, what is necessary is just to add the casing 1 and the core tube 2 as it becomes deep underground. By this excavation by simultaneous driving, a soil sample can be collected in the core tube 2, and as in the case of the step I, only the core tube 2 is pulled up to the ground, the soil sample in the core tube 2 is taken out, and a soil test is performed. Etc. can be performed. The casing 1 after the core tube 2 is pulled out is hollow. Then, a known standard penetration test may be performed again (end of step II).

  Next, excavation by simultaneous driving from 2 m to 3 m, removal of the core tube 2, insertion of a new empty core tube 2 and a standard penetration test are performed in the same manner as in Step II. In addition, it repeats similarly about 3 m or more depth, for example, it excavates to the desired depth like 10 m etc., and will extract | collect a soil sample (after III process).

  Conventionally, in the above process, when the core tube 2 is pulled out with the casing 1 left behind, a boiling phenomenon occurs. The boiling phenomenon occurs at a relatively shallow depth when the groundwater level is high, and at a depth of about 7 m to 10 m when the groundwater level is low. That is, as shown in FIG. 11, when the core tube 2 is pulled out from the state where the inner peripheral locking portion 12 of the casing 1 and the outer peripheral locking portion 32 of the core tube 2 are in close contact, the tip of the core tube 2 is pulled out. The portion becomes negative pressure, liquefaction occurs at the tip portion of the core tube 2 due to vibration during excavation, and the tip portion of the core tube 2 has earth pressure compared to the periphery of the core tube 2. For various reasons such as low (reduced load reduction) and the like, as shown in FIG. 12, when the core tube 2 is pulled out, the sandy soil 200 enters the casing 1 together with the ground water (boiling). When the sandy soil 200 enters the casing 1, it takes time to remove the soil remaining in the casing 1, and a collapse of the hole bottom ground occurs, so that there is a problem that the standard penetration test cannot be performed.

  Next, a method for digging a soil sampling pipe according to an embodiment of the present invention will be described with reference to FIGS. Since the soil sampling tube of the present invention uses the soil sampling tube of the present invention, the method of drilling the soil sampling tube of the present example can suppress the occurrence of boiling when the core tube 2 is pulled out. The excavation method of the soil sampling pipe in the embodiment of the present invention uses the soil sampling pipe of the present invention, pushes the casing into the ground by vibration and dead weight, and puts the soil sample in the core tube set inside the casing. This is a sampling method, in which water or muddy water is injected into the casing before, during or after setting the core tube inside the casing built in the ground, and the casing and the core tube are driven by simultaneous driving. When pulling up the core tube, using the method of performing the IA process of flowing water or mud from the groove (first method) and the soil sampling pipe of the present invention, while pushing the casing into the ground by vibration and its own weight, A method of collecting a soil sample in a core tube set inside a casing, where the casing and the core tube are driven simultaneously. Ri and excavation, when pulling only the core tube, the water or mud is injected between the casing and the core tube, a method of performing IB step of flowing down the water or mud from the groove (the second method) and the like. Hereinafter, water or muddy water is also simply referred to as “water”.

  That is, the method for digging a soil sampling tube of the present invention is different from the conventional method for digging a sampling tube except that the IA step in the first method or the IB step in the second method is performed. Is the method. In the description of the excavation method of the present invention, the “core tube 2” refers to the one in which the driving shoe 3 is attached to the tip. In the IA process in the first method, water is injected into the casing before, during or after setting the core tube inside the casing built in the ground, and the casing and the core tube are driven by simultaneous implantation. In the process of pulling up the core tube, water is allowed to flow down from the groove.

  “Before setting the core tube” means that water is injected into the casing 1 in a hollow state that is not inserted into the core tube and is embedded in the ground. This means that the core tube is inserted into the casing 1 in a hollow state built in the ground and water is injected at the same time. After the core tube is set, it is built in the ground. It means that water is injected after the core tube is inserted into the hollow casing 1. The term “set” means that the core tube 2 with the driving shoe 3 attached is inserted into the casing 1 so that simultaneous driving can be performed.

  The amount of water injected is not particularly limited, but may be an amount that allows the water level to be observed from the ground even when the water level in the casing 1 decreases as the digging progresses. Specifically, the water level in the casing 1 is preferably higher than the center of the height of the casing 1, preferably full. In the state where the core tube 2 is set in the casing 1, water enters the core tube 2, but there is no influence on the soil sample collection or the like.

  Next, digging to a predetermined depth is performed by simultaneous driving by the casing 1 and the core tube 2. At this time, sampling soil enters the core tube 2. The state of the tip part of the casing 1 and the core tube 2 at this time is shown in FIG. However, the description of water was omitted in FIG. In this state, additional water may be injected into the casing 1. Thereby, the water level which fell in the casing 1 can be raised, and observation of the water level from the ground is attained. After reaching a predetermined depth, the core tube 2 is pulled up. At this time, the water in the casing 1 flows down to the front end side of the casing 1 and the core tube 2 through the longitudinal groove 4a. In this way, water flows down and suppresses the generation of negative pressure, and the collected ground weight is replaced with water, and the weight of the water presses down the hole bottom ground, so that the occurrence of boiling can be suppressed (see FIG. 10). ).

  In addition, it can be confirmed by the fall of the water level in the casing 1 whether the water in the casing 1 was supplied to the front end side through the vertical groove 4a. As described above, when the core tube 2 is pulled out from the casing 1, there is no occurrence of boiling in the casing 1, so that the standard penetration test can be continued. The core tube 2 is pulled up to the ground, and the soil sample in the core tube 2 is observed.

  In the IB process in the second method, the casing 1 and the core tube 2 are dug by simultaneous driving, and when only the core tube 2 is pulled up, water is injected between the casing 1 and the core tube 2 and the water flows down from the vertical groove. It is a process to make. That is, it digs to a predetermined depth by simultaneous driving by the casing 1 and the core tube 2. At this time, sampling soil enters the core tube 2. After excavating to a predetermined depth, the excavation is stopped. The tip portions of the casing 1 and the core tube 2 at this time are in a state as shown in FIG. In this state, water is injected into the gap between the casing 1 and the core tube 2. Water may be injected from the ground into the gap between the casing 1 and the core tube 2 using an injection tool such as a kettle. The amount of water to be injected may be about several liters, which is smaller than that of the first method. Next, the core tube 2 is pulled up. At this time, the water in the casing 1 flows down to the front end side of the casing 1 and the core tube 2 through the longitudinal groove 4a. In this way, water flows down and suppresses the generation of negative pressure, and the collected ground weight is replaced with water, and the weight of the water presses down the hole bottom ground, so that the occurrence of boiling can be suppressed (see FIG. 10). ).

  Note that whether or not the water in the casing 1 has been supplied to the front end side through the longitudinal groove 4 a can be confirmed by a decrease in the water level seen in the gap between the casing 1 and the core tube 2. As described above, when the core tube 2 is pulled out from the casing 1, there is no occurrence of boiling in the casing 1, so that the standard penetration test can be continued. The core tube 2 is pulled up to the ground, and the soil sample in the core tube 2 is observed.

  In the method for digging a soil sampling pipe according to the present invention, the IA step in the first method or the IB step in the second method uses water, but a much smaller amount of water may be used as compared with the conventional water circulation method. Therefore, it is not necessary to install circulating equipment necessary for water circulation. Moreover, the excavation method of the soil sampling pipe of the present invention is not changed in principle, since it is a method performed by anhydrous excavation. Therefore, for the excavation up to about 5 to 6 m with a low groundwater level, which is presumed that no boiling will occur, an anhydrous excavation may be performed using a conventional driving shoe. Further, in the method for excavating the soil sampling pipe of the present invention, as the water, industrial water, fresh water, or muddy water can be used. Is preferable from the viewpoint of high. In the present invention, the groove is not limited to the vertical groove extending in the vertical direction as described above, and may be, for example, inclined or slightly bent as long as water can flow down.

  According to the present invention, it is possible to suppress the boiling phenomenon in dry excavation only by forming a groove at a specific location of the driving shoe. Further, according to the excavation method of the present invention, water circulation equipment is not required, and collapse of the hole bottom ground can be suppressed only by flowing a small amount of water. For this reason, the standard penetration test etc. which refrain from the next process can be performed smoothly.

DESCRIPTION OF SYMBOLS 1 Casing 2 Core tube 3a, 3b Driving shoe 12 Inner peripheral latching part 32 Outer peripheral latching part 4a, 4b Vertical groove 10 Soil sample collection pipe

Claims (5)

  A cylindrical casing and a core tube having a driving shoe inserted into the casing at a tip thereof are provided, and an inner peripheral surface on a tip side of the casing is contracted toward a tip side for locking the driving shoe. An annular inner peripheral locking portion that is continuous in the circumferential direction is formed, and the outer peripheral surface of the driving shoe is reduced in diameter toward the distal end side in contact with the inner peripheral locking portion, and the outer periphery continues in the circumferential direction. A soil sample collecting tube, wherein a locking portion is formed, and a groove is formed in the driving shoe so as to cross the outer periphery locking portion.   2. The soil sampling tube according to claim 1, wherein the groove is a longitudinal groove and is formed at one place or a plurality of places at an appropriate pitch in the circumferential direction.   3. The soil sampling pipe according to claim 2, wherein the groove extends from the upper end of the driving shoe to the front end side beyond the front end of the casing.   A method for collecting a soil sample in a core tube set inside the casing, using the soil sample collecting tube according to any one of claims 1 to 3 and pushing the casing into the ground by vibration and dead weight. When the core tube is set in the casing built in the ground before, during or after the setting, water or muddy water is injected into the casing, the casing and the core tube are driven simultaneously, and the core tube is pulled up. A method for digging a soil sampling pipe, wherein a step of flowing water or muddy water from the groove is performed.   A method for collecting a soil sample in a core tube set inside the casing, using the soil sample collecting tube according to any one of claims 1 to 3 and pushing the casing into the ground by vibration and dead weight. An earth sample characterized by performing a step of injecting water or muddy water between the casing and the core tube and allowing water or muddy water to flow down from the groove when the casing and the core tube are dug by simultaneous implantation and the core tube is pulled up. How to dig a sampling tube.

Images