JP2019052503A - Open pit method - Google Patents

Abstract

To provide an open pit method that does not interfere with an installation work of an underground burial structure by the fact that the ground sinks by the weight of the underground burial structure and that prevents surrounding houses from being tilted due to the ground subsidence.SOLUTION: Since ground water is absorbed from six water absorption pipes 19a inserted into the ground at an approximate bottom of a planned burial site where a box culvert 2 is to be buried from now on, it can be dried down to the ground, and the weight of the box culvert 2 will not cause the ground to sink. In addition, since the water absorption of the ground water is interrupted when the water absorption amount per unit time of the ground water measured in a water absorption amount measuring process is less than a predetermined amount, it will not absorb water more than necessary, and sinking will not cause surrounding houses to tilt.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an open pit construction method for burying underground buried structures such as box culverts using a Messel shield device.

  Conventionally, a method called an open shield method for burying underground buried structures such as box culverts is known. In this open shield method, a towed or self-propelled open shield machine (underground structure installation device) is installed in the excavated hole, and after the open shield machine is advanced, Underground structures were installed, and the open shield machine was advanced further, and the underground structures were sequentially connected by connecting them (for example, patents) Reference 1).

JP 2004-116179 A (Prior Art)

  In order to embed an underground buried structure, it is necessary to excavate a hole for burying the underground buried structure, and when this hole is excavated, groundwater may flow out from the bottom of the hole. Since this underground water affects the burial of underground structures, water collecting pipes are arranged at the bottom of the left and right sides of the underground burying structure installation equipment, and the groundwater collected on the ground is collected by submersible pumps. The collected groundwater was drained from the upper part of the underground buried structure installation device.

  However, when groundwater is collected only at the left and right bottoms of the underground buried structure installation device, the ground at the bottom of the planned underground site where the underground buried structure is to be installed remains soft, and the bottom of the central site of the planned buried site remains. If the underground structure is installed in a soft ground, the ground sinks due to the weight of the underground structure, which causes a problem in the installation of the underground structure. In addition, simply by collecting groundwater collected on the left and right bottoms of the underground buried structure installation device, the underground of the planned underground site where the underground buried structure is to be installed remains soft. If the underground structure is installed in the state where the underground part of the planned underground site is soft, the ground will sink due to the weight of the underground structure, and the installation of the underground structure will be hindered. Have

  In addition, when the groundwater flowing out from the bottom of the hole for burying the underground structure is absorbed, if the groundwater at the bottom of the hole for burying the underground structure is excessively sucked, ground subsidence occurs, and the surrounding houses The problem of tilting also arises.

  The present invention has been made in view of the above problems, and the ground sinks due to the weight of the underground buried structure, so that it does not hinder the installation work of the underground buried structure, and the surrounding houses due to the ground subsidence The object is to provide an open pit method that does not tilt.

  In order to solve the above problems and achieve the above object, the first aspect of the present invention relates to an open pit construction method for burying underground buried structures such as box culverts using a Messel shield device. The water absorption pipe installation process in which a plurality of water absorption pipes connected to the negative pressure generator are inserted into the ground at the bottom of the planned burial site to be buried, and the underground burial measured in advance The amount of water absorption set in the groundwater absorption amount setting process, which sets the amount of groundwater absorption per unit time, and the amount of water absorption set in the groundwater absorption amount setting process, based on the hydraulic conductivity of the bottom of the site where the structure is to be buried The groundwater absorption process that absorbs groundwater from the water absorption pipe by the water absorption capacity of the groundwater, and the water absorption that measures the amount of water absorbed per unit time by the groundwater absorption process. And a groundwater absorption interruption process that interrupts groundwater absorption when the amount of water absorption per unit time measured by the water absorption measurement process is less than a predetermined amount. If the water absorption of the groundwater is interrupted and the suspended state of the groundwater continues for a predetermined time, the groundwater is absorbed from the water absorption pipe by the water absorption capacity by which the groundwater absorption amount set in the groundwater absorption amount setting process is absorbed by the groundwater absorption process. It is characterized by making it.

  According to the present invention, since underground water is absorbed from a plurality of water intake pipes that are inserted into the ground at the substantially bottom of the planned embedding site where the underground buried structure is to be buried, the underground buried structure is buried from now on. It can be dried to the underground. Thereby, the ground does not sink due to the weight of the underground structure, and the installation work of the underground structure is not hindered. Moreover, since the water absorption of groundwater is interrupted when the water absorption amount per unit time of the groundwater measured by the water absorption amount measurement step is less than a predetermined amount, it is possible not to absorb more groundwater than necessary. Thereby, ground subsidence does not occur and surrounding houses can be prevented from tilting.

  Of the present invention, the second aspect is the open pit method according to the first aspect, wherein the water absorption measuring step measures the groundwater separated from the earth and gas mixed with the groundwater. It is characterized by doing.

  According to the present invention, since groundwater separated from soil and gas mixed with groundwater is measured, accurate groundwater can be measured, and the negative pressure generator can absorb groundwater without excess or deficiency. Thereby, it is possible to appropriately dry a place where an underground buried structure is to be buried, and to prevent the surrounding houses from being inclined due to ground subsidence.

  The third aspect of the present invention relates to the open pit construction method according to the first aspect or the second aspect, and is substantially in the ground at the bottom of the planned burial site where the underground buried structure is to be buried. And a plurality of water absorption pipes are inserted in a line at a substantially equal interval in a direction orthogonal to the traveling direction.

  According to the present invention, a plurality of water absorption pipes are installed in a line at substantially equal intervals in the direction perpendicular to the traveling direction in the ground at the substantially bottom portion of the planned buried site where the underground buried structure is to be buried. It is possible to uniformly dry the substantially bottom portion of the planned buried site of the buried structure.

  According to the present invention, since the ground sinks due to the weight of the underground buried structure, the installation work of the underground buried structure is not hindered, and the surrounding houses due to the ground subsidence are not inclined. it can.

It is the schematic which shows the construction condition of the Messel shield apparatus used for the open pit construction method in one Embodiment of this invention. It is a perspective view of the same Messel shield device. It is a top view of the same Messel shield device. (A) It is a front view of the Messel shield device. (B) It is a rear view of the Messel shield device. It is AA sectional drawing of Fig.4 (a). It is a vertical pipe front view of the main part of the drainage device, It is a figure which shows the use condition of the drainage device. It is a front view which fractures | ruptures and shows a part of foreign material removal member of the drainage device. It is a figure explaining the method of separating the gas mixed with groundwater from groundwater. It is a flowchart of the open pit construction method in one Embodiment of this invention. It is a figure which shows the construction condition of the open pit construction method.

  An open pit method according to an embodiment of the present invention will be described with reference to the drawings. Here, FIG. 1 is a schematic view showing the construction status of the Messel shield device used in the open pit method according to one embodiment of the present invention. In addition, although this embodiment demonstrates the case where the box culvert 2 is laid as an underground burying structure, an underground burying structure is not limited to the box culvert 2, and another underground burying structure may be sufficient. Here, the box culvert 2 is a structure embedded in a road and used for a sewer, a rainwater drain pipe, and the like.

  As shown in FIG. 1, the box culvert 2 is laid using a messel shield device 1 having a self-propelled function and embedded in the ground. Here, in the open pit construction method, the ground is excavated, the bottom of the excavated ground is solidified, and the messel shield device 1 having a self-propelling function is used on the solidified ground, and a box culvert 2 or the like is underground. This is a method of laying an embedded structure, and after the box culvert 2 is laid, it is returned to its original state even when the excavated ground is buried.

  Next, the Messel shield device using the open pit method according to an embodiment of the present invention will be described with reference to FIGS. 2 to 5 (mainly FIGS. 3 and 5). Here, FIG. 2 is a perspective view of the Messel shield device used in the open pit method according to one embodiment of the present invention, FIG. 3 is a plan view of the Messel shield device, and FIG. 4 is a front view of the device, FIG. 4B is a rear view of the Messel shield device, and FIG. 5 is a cross-sectional view taken along line AA of FIG.

  The Messel shield device 1 includes a rigid front frame 10 and a tail frame 20, and an intermediate jack 30 is connected between the front frame 10 and the tail frame 20. In the front frame 10, a cut beam 13 is disposed between left and right frames integrally formed of a vertical column member 11 and a horizontal reinforcing member 12. Further, the horizontal beam 21 extending in front of the tail frame 20 is placed on the support beam 14 extending in the rear of the front frame 10 and is configured to prevent the tail frame 20 from sinking. . A front message 40 and a tail message 41 are slidably arranged on both sides of the front frame 10 and the tail frame 20, and the front message 40 and the tail message 41 are connected by pins. The front frame 10 and each front message 40 are connected by a press-fit jack 15. Further, a bottom messel 17 is slidably disposed on the bottom of the front frame 10 via a bottom jack 16. Furthermore, a sled body 22 is disposed at the bottom of the tail frame 20. When the press-fit jack 15 is operated, the front message 40 is dug in the cutting direction, and when the bottom jack 16 is operated, the bottom message 17 is dug in the cutting direction. It is drawn toward the front frame 10. Control of the press-fit jack 15, the bottom jack 16, and the intermediate jack 30 is performed by a control unit 18 mounted on the upper portion of the front frame 10. In addition, a vacuum pump 19 is mounted on the upper part of the Messel shield device 1, and a water suction pipe 19a is connected to the vacuum pump 19 via a tube 19b. Here, six water-absorbing pipes 19a are provided. As will be described later, each water-absorbing pipe 19a is formed in a line in the direction perpendicular to the advancing direction of the Messel shield device 1, that is, in the horizontal direction at approximately equal intervals. Plugged in. As will be described later, the water absorption pipe 19a has a drainage device 19c at the tip for preventing foreign matters such as sand and gravel from entering the water absorption pipe 19a. In addition, in this embodiment, although the six water absorption pipes 19a (including the tube 19b) connected to the vacuum pump 19 were provided, not only this but 3-10 pieces (preferably 4-8 pieces) For example, a predetermined number may be provided. Further, in the present embodiment, the six water absorption pipes 19a are inserted into the ground in a row at substantially equal intervals in the horizontal direction. However, the present invention is not limited to this, and the water absorption pipes 19a are provided at any place other than the horizontal direction. May be inserted, or the water absorption pipe 19a may be inserted at a position where it is not opened at equal intervals in the lateral direction. In this embodiment, the vacuum pump 19 is provided. However, the present invention is not limited to this, and a negative pressure generator other than the vacuum pump 19 may be used.

  In the tail frame 20, the tail messels 41 are supported by a frame 25 integrally formed of a vertical column member 23 and a horizontal reinforcing member 24, and a plane U-shaped cut beam 26 is disposed in front of the frame 25 with a horizontal reinforcing member 24. Are arranged in a multi-stage configuration, and a reinforcing material 28 is provided at the joint between the cut beam 26 and the lateral reinforcing material 24. A suspending space 27 for suspending the box culvert 2 is formed between the opposing frame bodies 25. The hanging space 27 is open above and behind the space.

  Next, referring to FIGS. 3 and 4, the water suction pipe 19a connected to the vacuum pump (negative pressure generating device) installed in the ground at the bottom of the planned burying site where the box culvert 2 is to be embedded will be described. Will be described in detail.

  As described above, the water suction pipes 19a connected to the vacuum pump 19 are inserted in a line at substantially equal intervals in the direction orthogonal to the traveling direction of the message shield device 1, that is, in the lateral direction (see FIG. 4A). ). That is, six water absorption pipes 19a connected to the vacuum pump 19 are inserted into the ground at the substantially bottom portion of the planned embedding site where the box culvert 2 is to be embedded. Specifically, as will be described later, the ground in front of the Messel shield device 1 is excavated by a back fore, and the water absorption pipes 19a are arranged in a row in a direction perpendicular to the direction in which the Messel shield device 1 travels on the excavated ground. Is inserted (see FIG. 3). Then, after the box culvert 2 is installed using the Messel shield device 1, all six of the inserted water suction pipes 19a are pulled out, and the Messel shield device 1 is moved to a predetermined distance (the length of the box culvert 2). The pulled-out water absorption pipes 19a are again inserted in a row in the lateral direction perpendicular to the traveling direction of the Messel shield device 1 at the advanced position. As a result, the vacuum pump 19 is again inserted into the horizontal line at a position behind a predetermined distance that is the length distance of the box culvert 2 from the position where the vacuum pump 19 was previously inserted into the horizontal line. In this way, each time the box culvert 2 is installed by the Messel shield device 1, the insertion of the above-described water absorption pipe 19a → groundwater absorption → installation of the box culvert 2 → extraction of the water absorption pipe 19a → predetermined of the Messel shield apparatus 1 Distance progress → insertion of the water absorption pipe 19a is repeated. Here, the vacuum pump 19 is inserted into the ground to a depth of 50 cm. In the present embodiment, the water absorption pipe 19a connected to the vacuum pump 19 is inserted into the ground whenever the Messel shield device 1 travels the distance of the box culvert 2, but this is not restrictive. You may make it determine the timing which inserts the water absorption pipe | tube 19a connected with the vacuum pump 19 in the ground according to underground conditions, such as softness. Moreover, although the water absorption pipe | tube 19a connected with the vacuum pump 19 was inserted in the horizontal direction orthogonal to the advancing direction of the Messel shield apparatus 1, the direction orthogonal to the advancing direction of this Messel shield apparatus 1 is a strictly orthogonal direction. In this sense, it may be “a direction substantially orthogonal to the traveling direction of the Messel shield device 1”. Further, it is not always necessary to insert the water absorption pipes 19a in a row in a direction orthogonal to the traveling direction of the Messel shield device 1, and a plurality of water absorption pipes 19a are inserted into the ground at the bottom of the planned burial site where the box culvert 2 is to be buried. If it is to be installed in, you can freely decide the installation method according to the underground conditions. In this embodiment, the vacuum pump 19 is inserted to a depth of 50 cm. However, the present invention is not limited to this, and the vacuum pump 19 may be inserted to a depth of 50 cm to 100 cm. The height can be freely determined according to the underground conditions such as the strata and the softness of the ground.

  Next, a method for separating the earth mixed with the groundwater will be described with reference to FIGS. Here, FIG. 6 is a vertical pipe front view of the main part of the drainage device, FIG. 7 is a diagram showing a use state of the drainage device, and FIG. 8 is a partially broken foreign substance removing member of the drainage device. FIG. The drainage device of the present embodiment is the same as the drainage device described in Japanese Patent Application Laid-Open No. 2004-162453, and will be described with reference to the contents described in the publication.

  As shown in FIGS. 6-8, the drainage device 19c is provided in the lower part side of the water absorption pipe 19a, and has the main body 51, the connection port 52, the water absorption hole 53, and the foreign material removal member 54. As shown in FIG.

  The inside of the main body 51 is formed in a hollow shape, that is, a hollow shape is formed from the connection port 52 to the lower end portion of the main body 51. And it has the water flow path 55 in this hollow part, and is formed in the vertically long cylinder shape. Almost all of the main body 51 is buried below the ground c, that is, in the ground.

  The connection port 52 is provided on the upper side of the main body 51 and is screwed to the upper portion of the water absorption pipe 19a.

  A large number of the water absorption holes 53 are formed at a predetermined interval on the lower outer peripheral side of the main body 51, and the water passage 55 and the ground are communicated with each other through the water absorption holes 53.

  The foreign matter removing member 54 has a cylindrical shape slightly shorter than the axial length of the main body 51 and is provided so as to cover the outer side of the water absorption hole 53. That is, the foreign matter removing member 54 is formed in a relatively fine mesh shape and allows water to pass therethrough, but is configured to prevent passage of foreign matters such as sand and gravel. Thereby, foreign matters such as sand and gravel can be prevented from entering the water absorption holes 53, and the groundwater separated from the earth mixed with the groundwater is measured by a flow meter 58 (see FIG. 9) described later. Can do.

  Next, a method for separating the air mixed with the groundwater from the groundwater will be described with reference to FIG. Here, FIG. 9 is a diagram for explaining a method of separating gases mixed with the groundwater from the groundwater. In addition, although this embodiment demonstrates the method of isolate | separating the air mixed with groundwater, by using this method, other gases other than air can also be separated from groundwater.

  As shown in FIG. 9, the ground water absorbed by the vacuum pump 19 is sent to the separation tank 57 through the tube 19b. Here, the separation tank 57 is a tank for separating the air (gas) mixed with the groundwater absorbed by the vacuum pump 19. Specifically, when the groundwater absorbed by the vacuum pump 19 is sent to the separation tank 57 via the tube 19 b and stored in the separation tank 57, the air mixed with the groundwater becomes the inlet of the drain pipe 60 of the separation tank 57. It will float and move above the part. As described above, the air (gas) mixed with the groundwater does not flow into the flow meter 58 via the drain pipe 60 by the air below the separation tank 57 moving upward. In addition, when the groundwater is thrown into the separation tank 57, the air mixed with the groundwater thrown into the separation tank 57 is separated from the groundwater by colliding with the surface of the groundwater in the separation tank 57. Become.

  The electromagnetic valve 59 is a valve for opening or closing a flow path of groundwater drained through the drain pipe 60. That is, when the electromagnetic valve 59 is closed, the ground water in the separation tank 57 does not flow into the flow meter 58. Further, the electromagnetic valve 59 is controlled so that it is closed when the groundwater level in the separation tank 57 falls and reaches the position A of the separation tank 57, and the electromagnetic valve 59 opens when it reaches the position B. . Thus, when the level of groundwater in the separation tank 57 reaches the position of the point A above the drain pipe 60, the electromagnetic valve 59 is closed, so that the level of groundwater in the separation tank 57 is from the inlet of the drain pipe 60. The air at the upper surface of the groundwater in the separation tank 57 does not enter the drain pipe 60 without becoming the lower part. Further, since the air mixed with the ground water moves above the ground water in the separation tank 57, the air mixed with the ground water in the separation tank 57 does not enter the drain pipe 60. Here, about the point A, the air mixed with the ground water in the separation tank 57 rises and moves upward from the position of the inlet of the drain pipe 60 and is mixed with the ground water entering the drain pipe 60. This is a predetermined position where air is exhausted. Further, after the electromagnetic valve 59 is closed by the groundwater level in the separation tank 57 being at the position of the point A of the separation tank 57, the groundwater absorbed by the vacuum pump 19 is sent to the separation tank 57 and sent to the separation tank 57. When the groundwater level in 57 increases and the groundwater level in the separation tank 57 reaches the position B, the electromagnetic valve 59 is opened, and the groundwater in the separation tank 57 is introduced through the drain pipe 60. Thus, after the electromagnetic valve 59 is closed, the groundwater level in the separation tank 57 is increased by the groundwater absorbed by the vacuum pump 19, so that the groundwater in the separation tank 57 is sufficiently above the drain pipe 60. The air accumulated up to the position and mixed with the groundwater moves to a position above the entrance of the drain pipe 60. Thereby, the air (gas) mixed with the groundwater is not flown into the flow meter 58 via the drain pipe 60, and the groundwater separated from the air mixed with the groundwater can be measured by the flow meter 58. . In the present embodiment, “the air mixed with the groundwater moves to the upper part of the groundwater in the separation tank 57, so that the air mixed with the groundwater in the separation tank 57 enters the drain pipe 60. ”Disappears.” However, in reality, the air mixed with the ground water in the separation tank 57 that does not cause a problem in measuring the amount of groundwater with the flow meter 58 enters the drain pipe 60. Since air is an amount that does not pose a problem for measuring the amount of groundwater with the flow meter 58, this amount of air is ignored, and “the air mixed with the groundwater in the separation tank 57 is discharged into the drain pipe 60. “I ca n’t get inside.” The bypass valve 56 is a valve for preventing the vacuum pump 19 from sucking in groundwater. That is, when the bypass valve 56 is opened, the vacuum pump 19 sucks air. Thereby, the vacuum pump 19 does not absorb groundwater.

  As described above, the groundwater sucked by the vacuum pump 19 is mixed with earth (sand, gravel, etc.) and gas (air, etc.). However, by using the drainage device 19c, the earth (sand or sand) is mixed. Gravel, etc.) can be separated from groundwater, and gas (air, etc.) can be separated from groundwater by using the separation tank 57, etc., so that earth (sand, gravel, etc.) and gas can be separated. Pure ground water separated from the air (such as air) is sent to the flow meter 58, and the flow rate of the ground water can be accurately measured by the flow meter 58. ,

  Next, the permeability coefficient of the substantially bottom portion of the planned burial site of the box culvert 2 measured in advance will be described. The permeability coefficient of the substantially bottom portion of the planned burying place of the box culvert 2 is obtained by an on-site permeability test. This in-situ permeability test was conducted in both the horizontal direction both ends and the center (horizontal direction) of the box culvert 2 in the vertical direction (longitudinal direction) of the box culvert 2 in the length direction (longitudinal direction). 3 at equal intervals). In this embodiment, the on-site permeability test is performed every two lengths of the box culvert 2, but not limited to this, every three lengths of the box culvert 2 or five pieces. However, the place where the in-situ permeability test is carried out is to be carried out at both ends and the center of the planned burial site of the box culvert 2. One may be arranged at the center in the horizontal direction of the planned burial site, or five may be arranged at equal intervals in the horizontal direction.

  Next, the construction procedure of the open pit method in one embodiment of the present invention will be described with reference to FIG. FIG. 10 is a flowchart of an open pit method according to an embodiment of the present invention, and FIG. 11 is a diagram illustrating a construction status of the open pit method according to an embodiment of the present invention.

  First, in S1, an excavation process is performed. In this excavation process, a hole for burying a box carbonate (underground structure) is excavated using a back fore (see FIG. 11A). Then, the process proceeds to S2.

  In S2, a water absorption pipe installation step is performed. In this water absorption pipe installation process, six water absorption pipes 19a are inserted into the ground at the bottom of the planned embedding site where the box culvert 2 is to be buried, and are inserted in a horizontal line to a depth of 50 cm in the ground. Is done. Specifically, six water suction pipes 19a connected to the vacuum pump 19 mounted on the upper part of the front frame 10 of the Messel shield machine 1 via the tube 19b are arranged in the lateral direction perpendicular to the traveling direction of the Messel shield machine 1. It is installed by being inserted in a row at approximately equal intervals. This water absorption pipe 19a is inserted and installed at a lower position of the Messel shield machine 1 (see FIG. 3). Then, the process proceeds to S3.

In S3, a groundwater absorption amount setting step is performed. In this groundwater absorption amount setting step, the amount of absorption of groundwater per unit time to be absorbed from the absorption tube 19a is set based on the hydraulic conductivity of the substantially bottom portion of the planned burying area of the box culvert 2 measured in advance. In other words, the product of the bottom area of the planned burial site of one box culvert 2 and the previously measured hydraulic conductivity is set as the amount of groundwater absorbed. For example, if the bottom area of the planned burying area of the box culvert 2 is 15 m ² and the hydraulic conductivity is 0.6 cm / min, the amount of groundwater absorbed is 90 liters / min. Here, as the water permeability coefficient, the water permeability coefficient at the position where the water permeability coefficient is measured in the above-mentioned field water permeability test closest to the position of the water absorption pipe 19a installed in S2 is used. In the present embodiment, the water permeability coefficient at the position where the water permeability coefficient is measured in the above-described on-site water permeability test closest to the position of the water absorption pipe 19a installed in S2 is used as the water permeability coefficient. Alternatively, if the permeability coefficient measured in the on-site permeability test is a substantially equivalent value, one permeability coefficient such as an average value may be used. In addition, the permeability coefficient (such as an average value for each section) determined for each section may be used by dividing the section. Then, the process proceeds to S4.

  In S4, a groundwater absorption process is performed. In this groundwater water absorption process, the groundwater is absorbed from the water absorption pipe 19a by the water absorption force that absorbs the amount of groundwater set in the above-described groundwater absorption amount setting process. For example, water is absorbed by setting the water absorption amount of the vacuum pump 19 so that water is absorbed at the above-described water absorption amount (90 liters / minute). Specifically, if the water absorption amount set in the groundwater water absorption amount setting step is 90 liters / minute, the water absorption amount is 180 liters / minute for 5 seconds, the water absorption is stopped for 5 seconds, and the water absorption amount is 180 liters / minute. Thus, the water absorption is intermittently repeated for 5 seconds, resulting in the water absorption amount (90 liters / minute) set in the groundwater water absorption amount setting step. Thus, the amount of water absorption is set by changing the time interval between water absorption and stop. Here, the water absorption pipe 19a connected to the vacuum pump 19 is configured so that foreign matter such as sand and gravel does not enter the water absorption hole 53 by the foreign matter removing member 54 when water is absorbed. The groundwater separated is absorbed from the water absorption pipe 19a. Then, the process proceeds to S5.

  In S5, a water absorption amount measuring step is performed. In this water absorption amount measuring step, the amount of water absorption per minute (per unit time) of the groundwater absorbed by the groundwater water absorption step is measured. Specifically, the groundwater absorbed from the water absorption pipe 19 a is sent to the flow meter 58 via the separation tank 57. Since pure ground water separated from air is sent from the separation tank 57 to the flow meter 58, the flow meter 58 separates it from soil (removed in S4 (sand, gravel, etc.)) and gases (air, etc.). Pure groundwater will be measured. In this way, the water absorption amount per minute is measured by the flow meter 58. The amount of water absorption per minute of the groundwater is measured in units of one minute. That is, after measuring the amount of groundwater absorbed for one minute, the amount of water absorption is reset to “0”, and the amount of water absorbed for one minute is measured again. In this embodiment, the amount of water absorption per minute of groundwater is measured, but not limited to this, the amount of water absorption per unit time other than one minute may be measured, and 5 minutes is a unit for 5 minutes. The amount of water absorption per unit may be measured as the amount of water absorption per unit time. Then, the process proceeds to S6.

  In S6, it is determined whether all the steps of the open pit method have been completed. If all the processes of the open pit method are not completed, the process proceeds to S7. Whether all the processes of this open pit method have been completed or not, when all the processes of the open pit method are completed as well as when all the processes of the open pit method are not completed, It also includes the case where the process is completed in the middle of the open pit construction method, such as the case where the process ends when all processes are completed.

  In S7, it is determined whether the amount of water absorption per minute of groundwater measured by the water absorption amount measurement step is less than 1 liter. That is, after measuring the amount of water absorbed in the groundwater for one minute, it is determined whether the amount of water absorbed in the groundwater for one minute is less than 1 liter. And when the amount of water absorption of the 1 minute of groundwater is less than 1 liter, it progresses to S8. In the present embodiment, it is determined whether the amount of water absorption per minute is less than 1 liter, but is not limited to this, and may be less than another predetermined amount such as less than 3 liters or less than 5 liters.

In S8, an underground water absorption interruption process is performed. In this groundwater water absorption interruption process, it is interrupted that groundwater is absorbed from the water absorption pipe 19a started in the groundwater absorption process of S4. That is, the water absorption drive of the vacuum pump 19 is stopped, or the bypass valve 56 is opened and the vacuum pump 19 sucks air to interrupt the intake of groundwater from the water absorption pipe 19a.
Then, the process proceeds to S9.

  In S9, it is determined whether or not 30 seconds (predetermined time) has elapsed since the absorption of groundwater was interrupted by the above-described groundwater absorption stoppage process. If 30 seconds (predetermined time) has not elapsed, the process of S9 is performed again. The process of S9 is continued until 30 seconds (predetermined time) have passed. If it is determined that 30 seconds (predetermined time) has elapsed since the absorption of groundwater was interrupted, the process proceeds to S4, where the groundwater absorption process is performed, and the water absorption set in the groundwater absorption setting process as described above. The groundwater is absorbed from the water absorption pipe 19a by the water absorption force by which a large amount of groundwater is absorbed. In step S7, until it is determined that the water absorption amount per minute of groundwater measured in the water absorption amount measurement step is 1 liter (predetermined amount) or more, S8 → S9 → S5 → S6 → S7 → S8 (in S6, “ The process of “except for the case of“ YES ”” is repeatedly performed. If “NO” is determined in S7, the process proceeds to S10.

  In S10, it is determined whether to move the position of the water absorption pipe 19a. That is, the box culvert 2 is installed at the position of the current Messel shield machine 1 (see FIG. 11B), and the position of the water absorption pipe 19a needs to be moved (advanced) in order to install the next box culvert 2. If it is determined that it is not necessary to move the position of the water absorption pipe 19a, the process proceeds to S4, where the groundwater water absorption process is performed, and the water absorption amount of the groundwater set in the groundwater water absorption amount setting process is as described above. Water is absorbed from the water absorption pipe 19a. The process of S4 → S5 → S6 → S7 → S10 (except for the case of “YES” in S6 and “NO” in S7) is performed until it is determined in S10 that the position of the water absorption pipe 19a needs to be moved. Repeatedly. If “YES” is determined in S10, the process proceeds to S11.

  In S11, a water absorption pipe extraction step is performed. In this water absorption pipe drawing process, the vacuum pump 19 installed in the water absorption pipe setting process of S2 is drawn. Specifically, in the water absorption pipe installation process, all of the water absorption pipes 19a installed at approximately equal intervals in a horizontal row are pulled out. Then, the process proceeds to S12.

  In S12, a forward movement process of the Messel shield apparatus is performed. In the Messel shield device advancement step, the Messel shield device 1 is advanced. Specifically, the Messel shield device 1 is advanced by the length of the box culvert 2 in the longitudinal direction. This Messel shield device 1 penetrates the left and right front messels 40 one by one into the ground → the bottom messels 17 penetrate one by one into the ground → the press-in jack 15 and the bottom jack 16 are contracted (the front frame 10 advances) → The intermediate jack 30 is advanced by contracting (promoting the tail frame 20). And it progresses to S1 again.

  In S1, as described above, a hole (front of the Messel shield machine 1) from which a box carbonate (underground structure) will be embedded is excavated using a back fore. Then, the process proceeds to S2.

  In S2, a water absorption pipe installation step is performed. In this water absorption pipe installation process, a position that is a predetermined distance (the length distance of the box culvert 2) from the position where the six horizontal horizontal lines in the previous water absorption pipe installation process are installed at substantially equal intervals, that is, the Messel shield device of S12 A water absorption pipe 19a connected via a tube 19b and a vacuum pump 19 mounted on the upper part of the front frame 10 of the Messel shield machine 1 is positioned at a position behind a predetermined distance in which the Messel shield apparatus 1 is moved forward in the advance process. Six are installed in a horizontal row in a horizontal direction orthogonal to the traveling direction of the shield machine 1 at approximately equal intervals. Then, the process proceeds to S3.

  In S3, a groundwater absorption amount setting step is performed. In this groundwater water absorption amount setting step, as described above, the water absorption amount per unit time of water absorbed from the water absorption pipe 19a is set based on the hydraulic conductivity of the substantially bottom portion of the planned burial site of the box culvert 2 as described above. Is done. As described above, the water permeability coefficient is the same as the water permeability pipe 19a installed at S2 and the position where the water permeability coefficient is measured in the above-mentioned on-site permeability test. It is the same as described above that one water permeability coefficient such as an average value may be used if the measured water permeability coefficients are substantially equal. And the process of S4 and S5 is each implemented, and it is judged that each process of the open pit construction method was complete | finished by S6, and an open pit construction method is complete | finished.

  As described above, in the open pit construction method according to the present embodiment, groundwater is absorbed from the water suction pipes 19a inserted into the ground at the bottom of the planned burial site where the box culvert 2 is to be buried. Therefore, from now on, it can be dried to the underground where the box culvert 2 is to be embedded. As a result, the ground does not sink due to the weight of the box culvert 2, and the installation work of the box culvert 2 is not hindered. In addition, when the amount of water absorption per unit time measured by the water absorption amount measurement step is less than 1 liter (predetermined amount), the water absorption of the groundwater is interrupted. be able to. Thereby, ground subsidence does not occur and surrounding houses can be prevented from tilting.

  Further, since the ground water separated from the earth and gas mixed with the ground water is measured, the accurate ground water can be measured, and the vacuum pump 19 can absorb the ground water without excess or deficiency. Thereby, the place where the box culvert 2 is about to be buried can be appropriately dried, and the surrounding houses can be prevented from being inclined due to ground subsidence. Further, since the six water absorption pipes 19a are inserted into the ground at the substantially bottom portion of the planned burial site where the box culvert 2 is to be buried, in a direction orthogonal to the traveling direction in a line at substantially equal intervals, The substantially bottom portion of the planned burial site of the culvert 2 can be dried evenly.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Messel shield apparatus 2 Box culvert 10 Front frame 11 Vertical column material 12 Lateral reinforcement 13 Cut beam 14 Support beam 15 Press-in jack 16 Bottom jack 17 Bottom message 18 Control unit 19 Vacuum pump 19a Water absorption pipe 19b Tube 19c Drainage device 20 Tail frame 21 Horizontal beam 22 Sled body 23 Vertical column member 24 Horizontal reinforcing member 25 Frame 26 Cut beam 27 Suspension space 28 Reinforcing member 30 Intermediate jack 40 Front message 41 Tail message 51 Main body 52 Connection port 53 Water absorption hole 54 Foreign matter removing member 55 Water channel 56 Bypass valve 57 Separation tank 58 Flow meter 59 Electromagnetic valve 60 Drain pipe

Claims (3)

It is an open pit method of burying underground buried structures such as box culverts using a Messel shield device,
A water absorption pipe installation step in which a plurality of water absorption pipes connected to a negative pressure generator are inserted and installed in the ground at the substantially bottom of the planned burial site where an underground buried structure is to be buried;
A groundwater absorption amount setting step for setting a water absorption amount per unit time of water absorbed from the water absorption pipe based on a hydraulic conductivity of a substantially bottom portion of the planned underground site of the underground buried structure,
A groundwater water absorption step of absorbing groundwater from the water absorption pipe with a water absorption force by which the amount of groundwater set in the groundwater absorption amount setting step is absorbed;
A water absorption amount measuring step for measuring the amount of water absorption per unit time of the groundwater absorbed by the groundwater water absorption step;
A groundwater water absorption interruption step of interrupting water absorption of groundwater when the amount of water absorption per unit time measured by the water absorption amount measurement step is less than a predetermined amount;
If the groundwater absorption is interrupted by the groundwater absorption interruption step, and if the groundwater absorption interruption state continues for a predetermined time, the groundwater absorption amount set in the groundwater absorption amount setting step is absorbed by the groundwater absorption step. An open pit construction method characterized in that groundwater is absorbed from the water absorption pipe with a water absorption force.   2. The open pit construction method according to claim 1, wherein the water absorption measuring step measures groundwater separated from earth and gas mixed with groundwater. In the water absorption pipe installation step, a plurality of the water absorption pipes are inserted in a line at a substantially equal interval in a direction orthogonal to the traveling direction in the ground at the substantially bottom portion of the planned embedding site where an underground buried structure is to be buried. The open pit method according to claim 1 or 2, wherein

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