JP2019183440A - Construction method of underground structure - Google Patents

Abstract

To provide a construction method of an underground structure capable of constructing timbering of an earth retaining wall and an underground supporting body for improving a base ground, while simultaneously excavating in the earth retaining wall.SOLUTION: Curved boreholes 9, 11 reaching to the other end of an earth retaining wall 3 are drilled by starting a drilling rod 5 from the surface of an outer side of the earth retaining wall 3 and controlling rotation and non-rotation of the drilling rod 5 while applying vibration on the drilling rod 5 or a tip bid 7 to pass through a part of the earth retaining wall 3, after installing the earth retaining wall 3 in the ground 1. The curved borehole 9 is linearly drilled in an inner side of the earth retaining wall 3. The curved borehole 11 is drilled in a way that it is formed in a downward-convex curved shape inside of the earth retaining wall 3. Then, a preceding underground beam 35 and a freezing base ground 37 are constructed as an underground supporting body through a freezing method by arranging freezing tubes 25 and micro-channels 27 in curved borehole 9, 11 to circulate freezing refrigerant.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a construction method for an underground structure.

  Conventionally, when constructing a retaining wall, in order to prevent the inflow of groundwater into the excavated part and reduce the lifting pressure, the retaining wall has been embedded in the impermeable layer of the ground. In addition, when constructing a shaft deeper than the groundwater level, a method was proposed in which after excavating the shaft, the bottom of the shaft was cooled and frozen while groundwater was accumulated in the shaft wall, and the groundwater was discharged. (For example, refer to Patent Document 1).

  When excavating the interior of retaining walls, etc. constructed on soft ground, by repeatedly drilling holes from the ground surface inside the retaining walls etc. to a predetermined depth to form a columnar ground improvement body, A columnar ground improvement body was continuously installed in the horizontal direction to form a preceding underground beam.

Japanese Patent No. 5443200

  However, the method of laying the retaining wall up to the impermeable layer has a problem that the wall length becomes long and the construction cost increases. The method of freezing the groundwater by freezing the bottom of the shaft after excavation of the shaft is expensive because it requires a frozen thickness to counter the pressure of the groundwater. Moreover, since the groundwater in the shaft was drained after freezing, the construction efficiency was poor.

  The method of continuously installing columnar ground improvement bodies to form preceding underground beams repeats drilling work and work to form columnar ground improvement bodies many times, which makes construction inefficient and uneconomical. Met. In addition, it took time and effort to remove the improved body due to the excavation of the ground.

  The present invention has been made in view of the above-described problems, and its object is to provide an underground support for supporting the retaining wall and improving the bottom plate in parallel with excavation in the retaining wall. It is to provide a construction method of an underground structure that can be constructed efficiently.

  In order to achieve the above-described object, the present invention includes a step a in which a retaining wall is installed in the ground, and a drilling rod is started from the ground to vibrate the drilling rod or a tip bit of the drilling rod. By controlling the rotation and non-rotation of the drilling rod while striking, a bent boring hole that penetrates part of the retaining wall and reaches the other part of the retaining wall is drilled. It is the construction method of an underground structure characterized by comprising the process b and the process c which builds an underground support body using the said curved boring hole.

  In the present invention, by constructing the underground support body from the side of the retaining wall using a bent boring hole, it is possible to efficiently construct the underground support body for supporting the retaining wall and improving the bottom plate. . Moreover, an underground support body can be constructed in parallel with the step of excavating the earth retaining wall. The vibration component applied to the drill rod in the present invention may be in the axial direction or in a plurality of directions. By adding vibration components in a plurality of directions, drilling can be performed in the planned direction without fluctuation of the drilling direction even when the ground is hard or the hardness of the ground changes.

The lower end of the earth retaining wall may not reach the impermeable layer of the ground.
Construction cost can be reduced by shortening the wall length of the retaining wall.

The underground support is, for example, a frozen bottom plate constructed by a freezing method using a plurality of the bent boring holes.
By constructing a frozen bottom as an underground support, it is possible to ensure water-stopping at the lower end of the earth retaining wall.

It is desirable that a clot layer having a predetermined thickness or more is provided on the frozen bottom plate.
It is desirable that the predetermined thickness is set to a thickness that can suppress the swelling of the ground due to the covering groundwater pressure around the ground.
Accordingly, the weight of the frozen bottom plate and the clot layer can counter the groundwater lifting pressure, and the thickness of the frozen bottom plate can be reduced, which is economical.

When the underground support is a frozen bottom, in the step b, the bent boring hole has a curved shape that is convex downward between a part of the retaining wall and the other part of the retaining wall. It is desirable to drill holes.
At this time, in the step c, the frozen bottom plate is constructed in a downward dome shape or arch shape.
By obtaining the arch effect by forming the frozen bottom plate as a convex dome shape or arch shape downward, the groundwater lifting pressure applied to the frozen bottom plate can be transmitted from the earth retaining wall to the back ground. Also, the improved thickness of the frozen bottom plate can be reduced.

The underground support may be a preceding underground beam constructed by a freezing method.
By constructing a preceding underground beam as an underground support by a freezing method, the preceding underground beam can be melted and easily removed during excavation inside the retaining wall.

When the underground support is a preceding underground beam constructed by a freezing method, after step c, the ground above the preceding underground beam is excavated, and a part of the frame is placed inside the retaining wall. It may further comprise a step d of constructing and melting the preceding underground beam, and repeating the step b to the step d from the top to the bottom of the ground in order, and constructing the frame by a reverse winding method.
Thereby, it is possible to excavate the upper ground and construct the frame while constructing the lower preceding underground beam.

In the case of using a freezing method, in the step c, a freezing pipe is arranged in the bent boring hole, and a frozen refrigerant is circulated through the microchannel installed in the freezing pipe to form frozen soil around the bent boring hole. By doing so, it is desirable to construct the underground support.
Since the microchannel is lightweight and excellent in thermal conductivity, it is easy to arrange and can create frozen soil efficiently.

  ADVANTAGE OF THE INVENTION According to this invention, the construction method of the underground structure which can construct | assemble the underground support body for the support of a retaining wall and a bottom base improvement efficiently can be provided in parallel with the excavation in a retaining wall.

The figure which shows the process of drilling the curved boring holes 9 and 11 Sectional view near the tip bit 7 of the drilling rod 5 The figure which shows the method of arrange | positioning the freezing pipe | tube 25 in the curved boring holes 9 and 11. The figure which shows the process of arrange | positioning the freezing pipe | tube 25 in the curved boring holes 9 and 11, forming frozen soil, and starting excavation The figure which shows arrangement | positioning of the freezing pipe | tube 25 in the freezing bottom board 37 The figure which shows the state which complete | finished excavation of the ground 1 inside the earth retaining wall 3 The figure which shows the example which constructs the flat frozen bottom board 37a The figure which shows the example in which the earth retaining wall 43 is a rectangle by planar view The figure which shows the example in which the drilling rod 5 penetrates the other part 3b of the earth retaining wall 3 The figure which shows the example which constructs the housing 47 by the reverse winding method

Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a process of drilling the bent boring holes 9 and 11. FIG. 1A is a vertical sectional view of the ground 1 and shows a state where the uppermost bent boring hole 9 and the lowermost bent boring hole 11 are drilled. FIG.1 (b) is the figure seen from the direction of the arrow A shown to Fig.1 (a), and shows arrangement | positioning of the curved boring hole 11 by a bottom view. FIG. 2 is a cross-sectional view of the vicinity of the tip bit 7 of the drilling rod 5.

  As shown in FIG. 1, the earth retaining wall 3 is constructed on the ground 1. In the ground 1, for example, a sandy soil layer 15 exists below the viscous soil layer 13, and a viscous soil layer 17 that is an impermeable layer exists below the sandy soil layer 15. The lower end of the earth retaining wall 3 is located in the sandy soil layer 15 and does not reach the viscous soil layer 17. A boring machine 8 for driving the drilling rod 5 is installed on the ground 1 outside the retaining wall 3.

  As shown in FIG. 2, the drilling rod 5 is a tubular material, and a drilling direction determining member 19 is provided on the tip bit 7. The drilling rod 5 has great toughness. The drilling direction determining member 19 is attached so as to form a predetermined angle with respect to the axial direction of the drilling rod 5 (the direction of the arrow X shown in FIG. 2). A padding 21 is provided near the tip of the drilling rod 5. A transmitter (not shown) for position search is installed on the tip bit 7 of the drilling rod 5. The boring machine 8 is integrated with a gyro insertion / retraction device (not shown).

  The boring machine 8 can rotate the entire drill rod 5 as indicated by an arrow B. Furthermore, the drill rod 5 can be pushed out in the direction of the tip bit 7 as required. The drilling rod 5 is configured such that vibration is applied in the axial direction by the boring machine 8, or the tip bit 7 is hit by a hammer (not shown) installed on the base end side of the tip bit 7. The configuration.

  The drilling rod 5 goes straight by combining rotation and vibration in the axial direction on the drilling rod 5 or striking the tip bit 7. Further, by stopping the rotation of the drilling rod 5 and applying a vibration in the axial direction or hitting the tip bit 7 in a non-rotating state, drilling in the direction of the drilling direction determining member 19 is performed, The drilling direction can be bent in any direction. It is also possible to adjust the curvature of the drilling hole by adjusting the method of applying vibration or striking and the pushing force by increasing or decreasing the number of striking per unit time according to the condition of the ground to be excavated. .

  In the step shown in FIG. 1A, the boring machine 8 is used to control the rotation and non-rotation of the drilling rod 5 while applying axial vibration to the drilling rod 5 or hitting the tip bit 7. By doing so, the drilling rod 5 is started from above the ground 1, and the drilling rod 5 bends into the ground 1 to drill the boring holes 9, 11. When the part of the retaining wall 3 is cut from the outside, the drilling rod 5 is slightly retracted, and a solidified material or the like is injected from the tip bit 7 to form a water stop part 39 on the ground 1 around the cutting part. After that, drilling is resumed. Then, a part of the earth retaining wall 3 is penetrated to drill the inside of the earth retaining wall 3 and reach the other part of the earth retaining wall 3.

  As shown in FIG. 1A, the bent boring hole 9 is cut in a curved shape from the ground to a part of the retaining wall 3, and is drilled in a straight line inside the retaining wall 3. The bent boring hole 9 is drilled at a planned construction position of a preceding underground beam which is an underground support for supporting the retaining wall 3. In the vicinity of the bent boring hole 9, a hole (not shown) for temperature measurement is drilled.

  As shown in FIG. 1A, the bent boring hole 11 is cut in a curved shape as a whole, and is drilled in a curved shape convex downward inside the retaining wall 3. The bent boring hole 11 is drilled at a planned construction position of a frozen bottom plate which is an underground support for improving the bottom plate of the retaining wall 3. As shown in FIG. 1B, a plurality of the bent boring holes 11 are drilled at a predetermined interval inside the earth retaining wall 3, that is, within the planned construction range of the frozen bottom board, in a plan view. Further, a hole for temperature measurement (not shown) is drilled between the bent boring holes 11.

  In the process shown in FIG. 1, the position of a transmitter (not shown) installed on the tip bit 7 of the drilling rod 5 is searched in real time from the ground part during drilling of the ground 1 by the drilling rod 5. Further, by inserting a gyroscope (not shown) near the tip bit 7 of the drilling rod 5 and drawing it in at an appropriate time during drilling, using a gyro insertion / drawing device (not shown) integrated with the boring machine 8. Then, the drilling locus of the drilling rod 5 is measured.

  FIG. 3 is a view showing a method of arranging the freezing tube 25 in the bent boring holes 9 and 11. 3A is a view showing a state in which the removal member 23 is inserted into the drilling rod 5, FIG. 3B is a view showing a state in which the padding 21 has been removed, and FIG. The figure which shows the state which inserted the freezing pipe | tube 25 in the rod 5, FIG.3 (d) is a figure which shows the state which removed the drilling rod 5 from the bending boring holes 9 and 11. FIG.

  FIG. 4 is a diagram showing a process of placing frozen tubes 25 in the bent boring holes 9 and 11 to form frozen soil and starting excavation. FIG. 4A is a diagram showing a state in which the frozen pipe 25 is disposed in the uppermost bent boring hole 9 and the bent boring hole 11, and FIG. 4B is the uppermost preceding underground beam 35 and the frozen bottom plate 37. FIG. 4C is a diagram showing a state in which excavation of the ground 1 in the retaining wall 3 is started. FIG. 5 is a view showing the arrangement of the freeze tubes 25 in the freeze bottom plate 37. FIG. 5 is a view seen from the direction of the arrow G shown in FIG.

  In the step shown in FIG. 4A, the freezing tube 25 is disposed in the uppermost bent boring hole 9 and the bent boring hole 11. In order to arrange the freezing tube 25, first, as shown in FIG. 3 (a), the removal member 23 is inserted into the drilling rod 5 in the state shown in FIG. And stuffing 21 are connected. Then, as shown in FIG. 3 (b), the removal member 23 and the filling material 21 are removed from the drill rod 5.

  Next, as shown in FIG. 3C, the freezing tube 25 is inserted and arranged inside the drilling rod 5. Further, as shown in FIG. 3 (d), the drilling rod 5 is bent and removed from the boring holes 9 and 11. At this time, the water stop part 39 (FIG. 4A) outside the earth retaining wall 3 is reinforced with a solidifying material or the like. Further, the microchannel 27 is arranged in a band shape inside the freezing tube 25. The microchannel 27 is arranged in a section inside the retaining wall 3 in the freezing tube 25.

  The removal member 23, the freezing tube 25, and the microchannel 27 are bent from the ground surface and inserted into the boring holes 9 and 11. Further, the removal member 23, the stuffing 21, and the drilling rod 5 are pulled out from the bent boring holes 9 and 11 to the ground surface side as shown by the arrow C in FIG. 3A and the arrow D in FIG. 3C. It will be removed.

  The microchannel 27 is an extruded product made of aluminum and has a plurality of refrigerant circulation paths therein. The microchannel 27 has a socket 29 on the front end side and a socket 31 on the rear end side. A supply pipe 33a and a return pipe 33b are connected to the socket 31.

  In the step shown in FIG. 4A, after installing the freezing tube 25 and the microchannel 27 in the uppermost bent boring hole 9 and the bent boring hole 11, in the step shown in FIG. A freezing refrigerant is circulated between the microchannel 27 arranged in the freezing tube 25. The frozen refrigerant is carbon dioxide. The frozen refrigerant supplied from the freeze / thaw device 26 flows into the supply refrigerant circulation path in the microchannel 27 through the socket 31 from the supply pipe 33a shown in FIG. The refrigerant flows into the return refrigerant circulation path 27 and returns to the return pipe 33 b through the socket 31.

  In the step shown in FIG. 4B, by circulating the frozen refrigerant through the microchannel 27, the preceding underground beam 35 made of frozen soil is constructed around the section inside the retaining wall 3 of the bent boring hole 9. . The preceding underground beam 35 is an underground support for supporting the retaining wall 3.

  In the step shown in FIG. 4 (b), the frozen refrigerant is circulated through the microchannel 27, so that frozen soil is also formed around the section inside the retaining wall 3 of the bent boring hole 11, and the bottom of the retaining wall 3. The frozen bottom plate 37 is constructed. The frozen bottom plate 37 is an underground support for improving the bottom plate of the retaining wall 3. Since the bent boring holes 11 are drilled at a predetermined interval as shown in FIG. 2, the freezing pipe 25 is provided in a section inside the earth retaining wall 3 of the plurality of bent boring holes 11 as shown in FIG. 5. The frozen ground around the adjacent bent boring holes 11 is continuously integrated to form a dome-shaped frozen bottom board 37. The dome shape is a shape like a part of a sphere, and is a circular arc shape having a constant cross section in the radial direction.

  When the preceding underground beam 35 and the frozen bottom plate 37 are constructed by the freezing method, it is desirable to confirm the growth of frozen soil using an optical fiber sensor or the like installed in the temperature measuring hole described above. When the growth of the frozen soil is insufficient, the freezing range is expanded or a solidifying material is injected to ensure the strength and water stoppage of the preceding underground beam 35 and the frozen bottom plate 37.

  After the uppermost preceding underground beam 35 is constructed in the step shown in FIG. 4 (b), in the step shown in FIG. 4 (c), the interior of the retaining wall 3 of the ground 1 is moved to the uppermost preceding underground beam. Drill to a depth of 35. Thereafter, the uppermost preceding underground beam 35 is melted to return the ground 1 to the original state. When the preceding underground beam 35 is melted, warm water or the like may be passed through the freezing tube 25 to promote melting. After the preceding underground beam 35 is melted, the freezing tube 25 is removed if necessary, and an abdomen or a beam not shown is appropriately installed.

  In the first embodiment, as shown in each drawing of FIG. 4, the freezing pipe 25 is installed in the uppermost bent boring hole 9 to construct the preceding underground beam 35 and excavate the ground 1 thereabove. In parallel with the work, the second and third leading underground beams 35 are sequentially constructed. Then, the work of excavating the ground 1 and melting the preceding underground beam 35 is repeated downward.

  FIG. 6 is a diagram illustrating a state in which excavation of the ground 1 inside the retaining wall 3 has been completed. After melting the third-stage preceding underground beam 35, excavation of the ground 1 is completed with the soil layer 41 having a predetermined thickness remaining above the frozen bottom plate 37. The thickness of the clot layer 41 is set to a thickness that can suppress the swelling of the ground due to the covered groundwater pressure around the ground 1.

  In the state shown in FIG. 6, the groundwater pressure applied to the frozen bottom plate 37 is transmitted to the ground 1 on the back surface of the retaining wall 3 by the arch effect of the frozen bottom plate 37 as indicated by an arrow E. Further, as indicated by an arrow F, the weight of the clot layer 41 opposes the groundwater pressure. After this, an underground structure can be constructed in the excavation part.

  As described above, according to the first embodiment, using the bent boring hole 9 and the bent boring hole 11, the preceding underground beam 35 and the frozen bottom plate 37 that are underground supports from the side of the retaining wall 3. By constructing, the underground support can be efficiently constructed. If the preceding underground beam 35 is constructed from the side of the retaining wall 3, the excavation of the upper ground 1 and the construction of the lower preceding underground beam 35 can be performed in parallel.

  In the first embodiment, the preceding underground beam 35 that is no longer necessary when excavating the ground 1 inside the retaining wall 3 by constructing the preceding underground beam 35 and the frozen bottom plate 37 by the freezing method. Can be easily removed by melting. In addition, if the frozen bottom plate 37 that has become unnecessary is also thawed, it returns to the original ground 1, and natural restoration is easy.

  Furthermore, by constructing the frozen bottom plate 37, even when the lower end of the retaining wall 3 does not reach the water-impermeable layer (cohesive soil layer 17) of the ground 1, the water stopping property of the lower end portion of the retaining wall 3 can be reduced. Since it can be secured easily, the wall length of the retaining wall 3 can be shortened to reduce the construction cost.

  In the first embodiment, the bent boring hole 11 has a downwardly convex curved shape in the range inside the retaining wall 3, and a downwardly convex dome-shaped frozen bottom plate 37 is constructed. Since the dome-shaped frozen bottom plate 37 has an arch effect, the groundwater lifting pressure applied to the frozen bottom plate 37 can be transmitted to the ground 1 to the back surface of the retaining wall 3. Further, by providing a clot layer 41 having a predetermined thickness or more above the frozen bottom plate 37, the weight of the frozen bottom plate 37 and the clot layer 41 can counter the groundwater lifting pressure. Thus, even if the thickness of the frozen bottom board 37 is reduced, it is possible to prevent the board from swelling, and the construction cost can be reduced.

  In the first embodiment, the freezing tube 25 is disposed in the bent boring holes 9 and 11, and the freezing refrigerant is circulated through the microchannel 27 installed in the freezing tube 25. Since the microchannel 27 is lightweight and excellent in thermal conductivity, the microchannel 27 can be easily arranged and can create frozen soil efficiently.

  In the first embodiment, the frozen bottom plate 37 having a dome shape, that is, an arc shape having a constant cross section in the radial direction is constructed, but the shape of the frozen bottom plate is not limited to the dome shape. FIG. 7 is a diagram showing an example of constructing a flat frozen bottom board 37a. In the example shown in FIG. 7, the bent boring hole 11 a is drilled in place of the bent boring hole 11 of the first embodiment at the planned construction position of the frozen bottom board. The bent boring hole 11a is drilled in a curved shape from the ground surface to the retaining wall 3, and the inside of the retaining wall 3 is drilled in a straight line. The bent boring holes 11a are drilled inside the earth retaining wall 3 at a predetermined interval in plan view.

  After the bent boring hole 11a is cut, the freezing pipe 25 and the microchannel 27 are installed in the bent boring hole 11a to circulate the frozen refrigerant. As described above, since the bent boring holes 11a are cut at a predetermined interval, a plurality of frozen soils formed around the adjacent bent boring holes 11a are continuously integrated to form a flat plate shape. A frozen bottom plate 37a is constructed. When excavating the ground 1 inside the retaining wall 3, a block layer 41 a having a predetermined thickness is left above the frozen bottom plate 37 a.

  In some cases, the frozen bottom plate is constructed in an arch shape, that is, a shape in which an axial cross section is an arc having a certain size. FIG. 8 is a diagram illustrating an example in which the earth retaining wall 43 is rectangular in plan view. In the example shown in FIG. 8, the preceding underground beam 45 is constructed between a part 43 b and the other part 43 a of the retaining wall 43. In addition, the frozen bottom plate has an arch shape by continuously integrating the frozen soil created around a plurality of bent boring holes drilled in a curved shape convex downward inside the retaining wall. Built in.

  In the first embodiment, when the drilling rod 5 reaches the other part of the retaining wall 3, the drilling of the boring holes 9, 11 is stopped when the drilling rod 5 reaches the other part of the retaining wall 3. There is also a case of penetrating through. FIG. 9 is a view showing an example in which the drilling rod 5 penetrates the other part 3 b of the retaining wall 3. FIG. 9A is a diagram illustrating a state in which the drilling of the bent boring hole 11b is completed, and FIG. 9B is a diagram illustrating a state in which the frozen bottom plate 37 is constructed.

  In the example shown in FIG. 9, the bent boring hole 11 b drilled by the drilling rod 5 penetrates the other part 3 b of the retaining wall 3. In the step shown in FIG. 9 (a), when the drilling rod 5 cuts the other part 3b of the retaining wall 3 from the inner side, as in the case of cutting a part 3a of the retaining wall 3 from the outer side, It recedes a little and forms the water stop part 39b with a solidification material etc. In the step shown in FIG. 9B, the frozen bottom plate 37 is constructed by a freezing method using the bent boring hole 11b.

  In the first embodiment, the example in which both the preceding underground beam 35 and the frozen bottom plate 37 are constructed as the underground support has been described. However, the combined use of the preceding underground beam 35 and the frozen bottom plate 37 is not essential. For example, it is possible to construct only the frozen bottom board 37 using the bent boring hole 11 without constructing the preceding underground beam 35. Moreover, when the lower end part of the earth retaining wall 3 has reached the impermeable layer, it is not necessary to construct only the preceding underground beam 35 using the bent boring hole 9 and construct the frozen bottom plate 37.

  Next, a second embodiment will be described. FIG. 10 is a diagram illustrating an example of constructing a frame 47 that is an underground structure by a reverse winding method. In the second embodiment, differences from the first embodiment will be described, and the same points will be denoted by the same reference numerals in the drawings and the like, and description thereof will be omitted.

  In order to construct the frame 47 by the reverse winding method, first, as shown in FIG. 10 (a), the uppermost preceding underground beam 35 is constructed. At the same time, the second-stage bent boring hole 9 is drilled. And as shown in FIG.10 (b), the ground 1 is excavated to the upper side of the uppermost preceding underground beam 35, and the frame 47 is constructed | assembled. Simultaneously, the freezing tube 25 and the microchannel 27 are installed in the second-stage bent boring hole 9.

  Next, as shown in FIG. 10 (c), the uppermost preceding underground beam 35 is melted, and the freezing tube 25 and the microchannel 27 are removed. At the same time, the second-stage preceding underground beam 35 is constructed, and the third-stage bent boring hole 9 is drilled.

  Thereafter, as shown in FIGS. 10 (d) to 10 (f), the work for constructing the preceding underground beam 35 by drilling the bent boring hole 9 and excavating the ground 1 above the preceding underground beam 35 is excavated. Then, the work of constructing a part of the housing 47 inside the retaining wall 3 and melting the preceding underground beam 35 is repeated from the upper side to the lower side of the ground 1 to construct the housing 47 to a predetermined depth.

  As described above, in the second embodiment, by bending the boring hole 9 from the side of the retaining wall 3 and constructing the preceding underground beam 35, While excavating the upper ground 1 and constructing the frame 47, the preceding underground beam 35 can be constructed in the lower ground 1.

  Next, a third embodiment will be described. In the third embodiment, differences from the first embodiment will be described, and the same components will be denoted by the same reference numerals in the drawings and the description thereof will be omitted. The configuration described in the third embodiment can be combined with the second embodiment as necessary.

  In the third embodiment, the boring machine 8 shown in FIG. 1 applies vibrations in a plurality of directions to the drilling rod 5 shown in FIG. 2, and the entire drilling rod 5 is indicated by an arrow B shown in FIG. Rotate to The boring machine 8 may apply a vibration component to the drilling rod 5 in the direction of the arrow Y shown in FIG. 2, for example, or may apply vibration in three dimensions. Furthermore, the boring machine 8 can push out the drilling rod 5 in the direction of the tip bit 7 as required.

  The drilling rod 5 goes straight by combining rotation and vibration. Further, by stopping the rotation of the drilling rod 5 and applying vibration in a non-rotating state, drilling in the direction of the drilling direction determining member 19 is performed, and the drilling direction can be bent in an arbitrary direction. . In addition, the curvature of a hole can also be adjusted by adjusting the way of applying vibration and the pushing force.

  In the third embodiment, in the step shown in FIG. 1A, the ground is controlled by rotating and non-rotating the drill rod 5 while applying vibration to the drill rod 5 using the boring machine 8. 1 The drilling rod 5 is started from above, and the drilling rod 5 bends into the ground 1 to drill the boring holes 9 and 11. In the third embodiment, after drilling the bent boring holes 9 and 11, the preceding underground beam 35 and the frozen bottom board 37 are constructed in the same procedure as in the first embodiment.

  In the third embodiment, the same effect as in the first embodiment can be obtained. In addition, since the vibration applied to the drilling rod 5 and the impact applied to the tip bit 7 in the first embodiment are impacts in the axial direction, the impact force is attenuated when the rod is long, Since the vibration of the drilling rod 5 of the third embodiment is applied in a plurality of directions and propagates without attenuation even when the rod is long, long-distance drilling is possible.

  In the first embodiment, since excavation and excavation are performed forward by vibration or striking in the axial direction, it is difficult to excavate hard ground. However, in the third embodiment, the drilling rod 5 destroys the ground by vibration in a plurality of directions and drills the hole, and the axial pushing force from the rear hardly contributes to the drilling. Used only to advance. For this reason, even if it is a hard ground, concrete, etc., the front ground etc. can be drilled by vibration. Also, when drilling the vicinity of the boundary between the hard ground and the soft ground, in the first embodiment, the rod tip is located on the side of the soft ground because the forward excavation is performed by vibration or striking in the axial direction. However, in the third embodiment, the drilling rod 5 destroys the ground in front by vibrations in a plurality of directions and drills, so that the traveling direction is not shaken. As described above, according to the third embodiment, even when the ground is hard or the hardness of the ground changes, the drilling direction is curved in the planned direction without blurring the drilling direction. It can be carried out. Further, by applying vibrations in a plurality of directions, the mud can be promoted and the hole walls of the bent boring holes 9 and 11 can be stabilized.

  Note that the timing for constructing the preceding underground beam 35 by drilling the bent boring holes 9 in the second and lower stages is not limited to that described in the first to third embodiments. The preceding underground beam 35 in the second stage or lower may be constructed at a timing that can reliably support the retaining wall 3 when excavating the upper ground 1.

  In the example shown in FIGS. 1 to 10, the underground support such as the preceding underground beam and the frozen bottom plate is constructed by the freezing method, but the construction method of the underground support is not limited to this. For example, the underground support may be constructed by a chemical solution injection method or a high pressure injection method. Moreover, the installation of the clod layer shown in FIGS. 6 and 7 is not essential. Furthermore, the structure of the layer of the ground 1 is not limited to that shown in FIG.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these naturally belong to the technical scope of the present invention. Understood.

1 ......... Ground 3, 3a, 3b, 43, 43a, 43b ......... Securing wall 5 ......... Drilling rod 7 ......... Tip bit 8 ......... Boring machine 9, 11, 11a, 11b ... ... Bent boring holes 13, 17 ......... Cohesive soil layer 15 ......... Sandy soil layer 19 ......... Drilling direction determining member 21 ......... Filling material 23 ......... Removal member 25 ......... Freezing pipe 26 ... ...... Freezing and thawing device 27 ......... Microchannel 29, 31 ......... Socket 33a ......... Supply pipe 33b ......... Return pipe 35,45 ......... Preceding underground beam 37, 37a ......... Frozen bottom board 39, 39b ......... Water stop part 41, 41a ...... Clot layer 47 ......... Body

Claims (10)

A step of installing a retaining wall in the ground; and
The earth retaining rod is controlled by controlling rotation and non-rotation of the drilling rod while starting the drilling rod from the ground and applying vibration to the drilling rod or hitting a tip bit of the drilling rod. Drilling a bent boring hole penetrating a part of the wall and reaching the other part of the retaining wall; and
Constructing an underground support using the bent boring hole, c.
The construction method of the underground structure characterized by comprising.   The construction method for an underground structure according to claim 1, wherein the earth retaining wall has a lower end that does not reach the impermeable layer of the ground.   The construction method for an underground structure according to claim 1 or 2, wherein the underground support is a frozen bottom plate constructed by a freezing method using a plurality of the bent boring holes.   The construction method for an underground structure according to claim 3, wherein a clot layer having a predetermined thickness or more is provided on an upper part of the frozen bottom plate.   The construction method for an underground structure according to claim 4, wherein the predetermined thickness is set to a thickness capable of suppressing the swelling of the ground due to the covered groundwater pressure around the ground.   In the step b, the bent boring hole is drilled so as to have a downwardly curved shape between a part of the retaining wall and the other part of the retaining wall. 3. Construction method of underground structure according to 3.   The method for constructing an underground structure according to claim 6, wherein in the step (c), the frozen bottom plate is constructed in a downward dome shape or an arch shape.   The construction method for an underground structure according to claim 1 or 2, wherein the underground support is a preceding underground beam constructed by a freezing method. After the step c, further comprising a step d of excavating the ground above the preceding underground beam to construct a part of a frame inside the retaining wall and melting the preceding underground beam;
The construction method for an underground structure according to claim 8, wherein the step b to the step d are sequentially repeated from the upper side to the lower side of the ground, and the frame is constructed by a reverse winding method.   In the step c, by placing a freezing pipe in the bent boring hole, circulating a freezing refrigerant in a microchannel installed in the freezing pipe, and forming frozen soil around the bent boring hole, The construction method for an underground structure according to claim 3 or 8, wherein an intermediate support is constructed.

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