JP2017122358A - Earth retaining frame - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earth retaining frame capable of securely supporting an earth retaining wall even when a site on the rear side of the earth retaining wall is narrow or no anchor fixing ground exists behind the earth retaining wall.SOLUTION: An earth retaining frame 1 comprises: an earth retaining wall 10 extending vertically; a bracing pile 20 provided on the ground on the opposite side to the excavation region side of the earth retaining wall 10; a second wale member 22 provided on the bracing pile 20's side face on the opposite side to the earth retaining wall 10; and a pair of connection members 30 into which tension force is introduced, the connection members connecting the earth retaining wall 10 with the bracing pile 20 through the second wale member 22. The connection members 30 are buried in a ground improvement layer 4.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a mountain retaining frame including a mountain retaining wall constructed surrounding an excavation area.

Conventionally, as a method of supporting the retaining wall, there is a tie rod construction method in which a retaining pile is driven on the ground on the back of the retaining wall, and the retaining pile and the retaining wall are connected by a tie rod (connecting material) (Patent Document 1). reference).
However, in Patent Document 1, the retaining pile is driven alone into the ground of the non-excavation region, and the mountain retaining wall is supported by the retaining pile alone via a tie rod. Therefore, the plurality of stake piles driven into the ground are not connected to each other, and the plurality of stake piles cannot form a group to suppress the slope of the mountain retaining wall. Therefore, a plurality of reserve piles could not stand up and resist as a whole.

  In addition, as a structure of the revetment sheet pile wall, a guard is placed on the ground behind the revetment sheet pile wall, and the revetment sheet pile wall and the guard are connected with Thai material, and the ground between the revetment sheet pile wall and the guard is also provided. It is known to improve the ground (see Patent Document 2).

However, in Patent Document 2, in the revetment work, the ground between the revetment sheet pile wall and the preparatory work is improved, but no tension is introduced in Thai materials, and the revetment sheet pile wall is caused by earth pressure. There was a risk of bulging outward and deforming.
In addition, the structure of the revetment structure is to prevent the liquefaction of the soft ground by providing a ground improvement soil and a concrete layer on the surface ground part between the revetment steel sheet pile and the ground pile. Yes. The invention of Patent Document 2 is a liquefaction prevention technology for a wide range of surface ground on the inner side of the revetment structure, and is a two-way surface shape composed of steel sheet piles and surface ground portions such as ground improvement layers and concrete layers. The material suppresses the shearing behavior of the ground. The revetment structure of Patent Document 2 is not a reinforcement structure that increases the degree of soil restraint for a part of the ground, so that the construction range is widened and the construction cost is high.

JP 2014-5650 A JP 2011-236657 A

  In light of the above problems, the present invention ensures that the mountain retaining wall is secured even when the site on the back side of the mountain retaining wall is narrow, the rear side of the mountain retaining wall is soft ground and the ground anchor cannot be fixed. The purpose is to provide a supportable mountain structure.

  The present inventor, as a mountain frame that does not use a ground anchor, drives a plurality of retaining piles into the ground on the back of the retaining wall, and uses the retaining wall, the retaining pile, and a connecting member that introduces a tension force. In addition to forming a gate-type frame in the back ground of the building, and changing the soft ground in the gate-type frame to a ground improvement layer to increase the degree of restraint by soil, the tension force introduced into the connecting member and secondary excavation Focusing on the fact that the mountain retaining wall and the retaining pile can be integrated into the shear force against the horizontal force accompanying the increase in the lateral pressure, the present mountain retaining structure was invented.

  Further, the present inventor improved the ground between the mountain retaining wall and the retaining pile, thereby improving the tensile force at the time of pre-tension applied to the connecting member and the increase in the side pressure at the time of secondary excavation. In order to resist the increase of the tensile force generated in, the mountain retaining frame with increased passive resistance has been invented.

  The mountain retaining frame (for example, a mountain retaining frame 1 described later) of the first invention is opposite to a mountain retaining wall (for example, a mountain retaining wall 10 described later) extending in the vertical direction and the excavation region side of the mountain retaining wall. A storage pile (for example, a storage pile 20 described later) provided on the ground on the side, and a belly raising member (for example, a second stomach described below) provided on the side surface of the storage pile opposite to the mountain retaining wall. And a pair of connecting members (for example, a connecting member 30 to be described later) that connect the mountain retaining wall and the reserve pile and introduce a tension force through the raised member. The connecting member is embedded in a ground improvement soil (for example, a ground improvement layer 4 described later).

According to the first invention, the mountain retaining wall and the retaining pile are joined by the pair of connecting members via the erection member that extends along the retaining pile and extends on both sides of the retaining pile. Thus, even if the central axis of the main pile and the central axis of the retaining pile constituting the mountain retaining structure are slightly shifted in plan view, the pair of connecting members are in a state where a predetermined distance is secured with the retaining pile interposed therebetween. Since it is arrange | positioned, it connects firmly, without applying an eccentric load to a mountain retaining wall and a retaining pile.
In addition, since the connecting member is buried in the ground improvement soil, the ground between the retaining wall and the retaining pile against the tension force introduced into the connecting member and the horizontal force due to the increase of the side pressure due to the secondary excavation The resistance force by the improved layer is increased, and the structural stability of the mountain frame can be secured.

Specifically, according to the first invention, even if the back side of the mountain retaining wall is soft ground, the soft retaining ground is replaced with ground improved soil, and the mountain retaining wall and the retaining pile are sandwiched between the ground improved soil. By connecting this mountain retaining wall and the retaining pile with a connecting member that introduces tension, without increasing the size of the core of the mountain retaining wall or reducing the interval between the core members A stable mountain wall can be constructed. Moreover, pre-tensioning (preload) is given to the connecting member that connects the retaining pile and the retaining wall, and the retaining wall is directed toward the retaining pile by pulling the retaining wall to the retaining pile in advance. When moving, it is counteracted by the passive earth pressure acting on the retaining wall as its reaction force, preventing the retaining wall from protruding.
Further, it is not necessary to provide a structure for supporting the mountain retaining frame on the excavation area side of the mountain retaining wall, and since there is no obstacle on the excavation area side, underground excavation can be performed in a short construction period.

According to a second aspect of the present invention, the ground improvement soil is formed by replacing the soil above the lower end surface of the connecting member, or by mixing and stirring a cement-based solidifying material in the soil. It is characterized by being.
Specifically, the ground improved soil is a soil having characteristics that both the adhesive force and the internal friction angle or only one of the adhesive force and the internal friction angle is higher than those of the raw soil.

  According to the second invention, the degree of soil restraint (adhesive force and internal friction angle) between the retaining wall and the pile is replaced by replacing the raw soil above the lower end surface of the connecting member with ground improved soil. Is increased, and the ground area that behaves as one piece increases. Therefore, when the mountain retaining wall or the retaining pile tries to move in the horizontal direction, the passive earth pressure region that generates the reaction force is increased, so it is possible to reliably prevent the mountain retaining wall and the retaining pile from inclining. .

In addition, by performing ground improvement only in the minimum area where it is necessary to improve the ground characteristics between the mountain retaining wall and the retaining pile, construction can be done in a short period of time and while suppressing temporary construction costs, Prevents the wall from protruding.
In addition, by improving the ground with cement-based solidifying material, the cost for carrying out the raw soil and disposing of it becomes unnecessary, and the cost for purchasing the ground improved soil from outside the site becomes unnecessary, so that the ground improvement cost can be reduced. In addition, the construction period can be shortened because there is no out-of-field unloading process and no ground improvement soil loading process.

  In addition, the ground soil between the retaining pile and the retaining wall has been improved and the soil restraint level has been increased, causing a reaction force when the retaining wall and retaining pile attempt to move horizontally. In the passive earth pressure region, the generation strength (shear slip failure strength) of shear slip failure occurring at the edge increases, so that shear slip failure can be prevented and the retaining wall can be reliably supported. It can also be used as a work floor for heavy machinery by improving the ground.

  According to a third aspect of the present invention, the ground improvement soil replaces the raw soil above the lower end surface of the connecting member and around the tip end portion of the retaining pile, or a cement-based solidified material in the raw soil. It is formed by mixing and stirring.

  According to the third invention, in addition to the effect of the second invention, the ground improvement is also performed around the reserve pile, thereby suppressing the temporary construction cost and increasing the degree of restraint of the soil around the reserve pile. Thus, the earth pressure resistance of the pile can be increased.

  The retaining frame of the fourth invention comprises a retaining wall extending in the vertical direction, a retaining pile provided on the ground opposite to the excavation area side of the retaining wall, and the retaining wall of the retaining pile. Is provided with a flank member provided on the opposite side surface, and a pair of connecting members that connect the mountain retaining wall and the stake pile via the flank member and in which tension is introduced. In the range where passive resistance is generated in the retaining pile on the ground surface between the mountain retaining wall and the retaining pile, embankment or a temporary heavy object (for example, embankment 5 described later) is provided. .

According to the mountain frame of the fourth invention, the embankment or the temporary heavy object is provided in the range where the passive resistance is generated in the storage pile on the ground surface, so that the passive earth pressure of the storage pile can be increased. Thereby, the movement to the mountain retaining wall side of a retaining pile can be suppressed more effectively, and the protrusion of a mountain retaining wall can be prevented.
As described above, a stable mountain retaining wall can be constructed without increasing the size of the core material of the mountain retaining wall or reducing the interval between the core members.

Moreover, pre-tensioning (preload) is given to the connecting member that connects the retaining pile and the retaining wall, and the retaining wall is directed toward the retaining pile by pulling the retaining wall to the retaining pile in advance. When moving, it is counteracted by the passive earth pressure acting on the retaining wall as its reaction force, preventing the retaining wall from protruding.
Further, it is not necessary to provide a structure for supporting the mountain retaining frame on the excavation area side of the mountain retaining wall, and since there is no obstacle on the excavation area side, underground excavation can be performed in a short construction period.

  According to the present invention, even when the site on the back side of the mountain retaining wall is narrow, or when there is no anchor fixing ground if there is a predetermined space on the rear surface of the mountain retaining wall, the method for increasing the rigidity of the mountain retaining wall. As described above, it is possible to construct the mountain retaining wall in a short construction period without increasing the size of the core material of the mountain retaining wall or reducing the interval between the core members.

It is a longitudinal cross-sectional view of the mountain retaining frame concerning 1st Embodiment of this invention. It is a top view in the AA cross section position of FIG. It is BB sectional drawing of FIG. It is explanatory drawing of the operation | movement of the mountain retaining frame concerning embodiment. It is a flowchart of the procedure which constructs the mountain retaining frame concerning an embodiment. It is a longitudinal cross-sectional explanatory drawing (the 1) of the procedure which constructs the mountain retaining frame which concerns on embodiment. It is a longitudinal cross-sectional explanatory drawing (the 2) of the procedure which constructs the mountain retaining frame which concerns on embodiment. It is a longitudinal cross-sectional explanatory drawing (the 3) of the procedure which constructs the mountain retaining frame concerning embodiment. It is a longitudinal cross-sectional explanatory drawing (the 4) of the procedure which constructs the mountain retaining frame concerning embodiment. It is explanatory drawing of the design method of the reserve pile of this invention. It is a schematic diagram of the mountain retaining frame concerning 2nd Embodiment of this invention. It is a schematic diagram of the mountain retaining frame concerning 3rd Embodiment of this invention. It is a schematic diagram of the mountain retaining frame concerning 4th Embodiment of this invention. It is a horizontal sectional view of the mountain retaining frame concerning the modification of the present invention.

The present invention is a mountain retaining structure in which the raw soil on the back side of the mountain retaining wall is replaced with ground improved soil, and a connecting member is embedded in the ground improved soil to connect the mountain retaining wall and the retaining pile.
Specifically, a mountain retaining structure (first embodiment) in which the raw soil above the lower end surface of the connecting member is replaced with ground improved soil, and the ground pile on the upper side of the connecting member and the lower side of the connecting member. A mountain retaining structure with the surroundings replaced (second embodiment) and a ground retaining structure provided with ground improvement soil on the upper side of the connection member and a temporary heavy object provided on the upper surface of the ground improvement soil around the retaining pile (third embodiment) Mode) and a ground retaining structure (fourth embodiment) in which ground improvement soil is provided on the upper side of the connecting member, and a connecting surface material of the lower piles is provided on the side of the upper side of the connecting member.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[First Embodiment]
FIG. 1 is a longitudinal sectional view of a mountain retaining frame 1 according to the first embodiment of the present invention, and FIG. 2 is a plan view of the mountain retaining frame 1 at the AA cross-sectional position.
In this embodiment, the mountain retaining frame 1 includes a mountain retaining wall 10 extending in the vertical direction, and a plurality of retaining piles 20 provided on the ground 2 opposite to the excavation region side of the retaining wall 10, that is, on the back side. The 2nd erection 22 which connects these storage piles 20 and the some connecting member 30 which connects the mountain retaining wall 10 and the storage pile 20 in the state by which tension | tensile_strength was introduced are provided.

  The Yamadome wall 10 is an SMW (Soil Mixing Wall) continuous wall. This SMW continuous wall is a wall formed in the ground by mixing and stirring soil and cement slurry in-situ, and H-shaped steel is provided as a core material 12 at predetermined intervals.

On the mountain retaining wall 10, a first erection 13 is laid over a plurality of core members 12.
The first erection 13 is disposed in contact with the side surface of the core member 12 on the excavation region side, and extends in the horizontal direction. The first upset 13 is configured by placing substantially U-shaped channel steels back and forth in a back-and-forth manner. Here, the lower channel steel is referred to as the lower belly 14 and the upper channel steel is referred to as the upper belly 15.

  A plurality of the reserve piles 20 are arranged at predetermined intervals along the mountain retaining wall 10, and the second erections 22 are laid over the plurality of reserve piles 20.

  The second erection 22 is disposed in contact with the side surface opposite to the excavation region of the storage pile 20 and connects the plurality of storage piles 20 in the horizontal direction. The second erection 22 is configured by arranging substantially U-shaped channel steels back to back. Here, the lower channel steel is referred to as the lower belly 23 and the upper channel steel is referred to as the upper belly 24. In addition, one side surface of the second upset 22 functions as a surface material that increases the degree of soil restraint between the mountain retaining wall 10 and the retaining pile 20, thereby increasing the earth pressure resistance of the soil. be able to.

  The connecting member 30 is installed as a pair on both sides with each holding pile 20 interposed therebetween. By arranging the connecting members 30 as a pair, the retaining wall 10 and the retaining pile 20 can be fixed without giving an eccentric load to the retaining pile 20, and the structural safety of the retaining structure can be improved. .

  The connecting member 30 includes a threaded reinforcing bar 31 having a screw formed on the outer peripheral surface, a first fixing member 32 that is engaged with the first raised portion 13 of the retaining wall 10 and through which the threaded reinforcing bar 31 passes, and a holding member. A second fixing member 33 that is locked to the second flank 22 of the pile 20 and through which the threaded reinforcing bar 31 passes, and a first fixing member 32 and a second fixing member that are screwed to both ends of the threaded reinforcing bar 31. The first nut 34 and the second nut 35 serving as fastening members that are locked to the member 33 and a covering member 36 that covers the threaded reinforcing bar 31 are provided. As the covering member 36, a drainage polyvinyl chloride pipe (VU pipe) or a rigid polyvinyl chloride pipe (PVC pipe) whose inner peripheral wall surface is smooth so that the screw of the threaded reinforcing bar 31 is not caught on the inner peripheral wall surface of the covering member 36. ) Is preferred.

  The connection member 30 was a screw-in reinforcing bar that was stronger and lighter than steel materials such as SS400. Further, steel fixing tools (off-the-shelf products) integrated by casting are used for the first fixing member 32 and the first nut 34, or the second fixing member 33 and the second nut 35, respectively. As a result, the fixing members 32 and 33 can be installed, and the process of tightening with the nuts 34 and 35 can be performed simultaneously, and tension can be introduced in a short construction period. Further, the installation height of the connecting member 30 is set at a height position equal to or higher than 2/3 of the height of the mountain retaining wall 10 in order to suppress the mountain retaining wall 10 from being inclined to the excavation region side by a small amount of steel material. It is preferable to install.

The threaded reinforcing bar 31 is embedded in the ground improvement layer 4 made of ground improved soil, and a pair of threaded reinforcing bars 31 are arranged with the holding pile 20 interposed therebetween.
The end portion of the threaded reinforcing bar 31 on the mountain retaining wall 10 side is disposed between the lower belly ridge 14 and the upper belly ridge 15 of the first belly 13. The first fixing member 32 is disposed on the side surface of the first erection 13 on the side of the excavation area, and the first nut 34 is disposed on the first fixing member 32.

  The end portion of the threaded reinforcing bar 31 on the side of the retaining pile 20 is disposed between the second belly ridge 22 and the lower belly ridge 23 and the upper belly ridge 24. The second fixing member 33 is disposed on the side surface of the second erection 22 opposite to the excavation region side, and the second nut 35 is disposed on the second fixing member 33.

  The covering member 36 is a cylindrical resin or steel pipe, and the threaded reinforcing bar 31 is inserted through the covering member 36. As shown in FIG. 3, the screw thread reinforcing bar 31 is arranged on the lower end surface inside the covering member 36, and thereby a space is secured on the side and above the screw thread reinforcing bar 31.

  In the portion between the mountain retaining wall 10 and the retaining pile 20 and above the lower end of the connecting member 30, the ground soil of the ground 2 is replaced with ground improved soil having higher adhesive force and higher internal friction angle than this ground soil. As a result, the ground improvement layer 4 is formed, whereby the connecting member 30 is embedded in the ground improvement layer 4.

Next, the operation of this embodiment will be described.
As shown in FIG. 4, a main earth pressure is applied to the mountain retaining wall 10 to constantly move the soil in the horizontal direction due to the vertical load of the soil 2 or the ground improvement layer 4 on the back soil of the mountain retaining wall 10. P is acting. Therefore, the mountain retaining wall 10 is pulled toward the retaining pile 20 by the tensile force F introduced into the connecting member 30, but the main earth pressure P is in a balanced state as a reaction force of the tensile force F. In addition, the holding pile 20 is also in a state where the tensile force F to the mountain retaining wall 10 side and the main earth pressure P are balanced.

  A case is assumed where the mountain retaining wall 10 and the retaining pile 20 are about to move in the horizontal direction. When the space between the mountain retaining wall 10 and the retaining pile 20 is the raw soil, the region between the shear wall shear failure surface A and the retaining wall 10 or the retaining pile 20 due to the raw soil shown in FIG. 4 is activated. It becomes the earth pressure area. On the other hand, when the ground retaining wall 10 and the retaining pile 20 are ground improved soil, the shear shear sliding fracture surface B by the ground improved soil shown in FIG. 4 and the retaining wall 10 or the retaining pile 20 The area between the two becomes the passive earth pressure area, and the passive earth pressure area expands. Therefore, in the present invention, the ground improvement soil constituting the ground improvement layer 4 is preferably as the adhesive force and the internal friction angle are higher in order to prevent the slope 10 of the mountain retaining wall 10 from projecting when an earthquake occurs.

Hereinafter, the procedure for constructing the mountain frame 1 will be described with reference to the flowchart of FIG.
In step S1, a mountain retaining wall 10 extending in the vertical direction is constructed on the ground 2 as shown in FIG. In step S2, as shown in FIG. 6, the reserve pile 20 is driven on the ground 2 opposite to the excavation area of the retaining wall 10, that is, on the back side.
In step S3, as shown in FIG. 7, the excavation area side and the back side of the retaining wall 10 are excavated to expose the upper part of the retaining wall 10 and the upper part of the retaining pile 20.

  In step S4, as shown in FIG. 7, first, the first uplift 13 is installed on the wall surface side of the excavation area of the retaining wall 10 in the direction parallel to the ground surface, and a plurality of the storage piles 20 are connected to each other. Connect with 2 angling 22. Next, the connecting member 30 is installed between the mountain retaining wall 10 and the holding pile 20 at a predetermined interval.

  Specifically, first, the first belly 13 and the lower belly protuberance 14 are installed, and the second belly 22 and the lower belly protuberance 23 are installed. Next, the threaded reinforcing bar 31 is inserted into the covering member 36, and the threaded reinforcing bar 31 is raised on the lower stage 14 and placed on the upper part 14 and 23. Next, the first belly 13 and the upper belly 15 are erected on the threaded reinforcing bar 31, and the upper belly 24 of the second belly 22 is erected.

In step S5, as shown in FIG. 8, the soil 3 is buried back on the connecting member 30. Specifically, the earth 3 is backfilled so that the screw rebar 31 is disposed on the lower end surface inside the covering member 36.
At this time, a cement-based solidifying material is mixed with the raw soil that is the excavation soil of the ground 2 between the mountain retaining wall 10 and the retaining pile 20 in a side view and above the lower end of the connecting member 30. Backfill the agitated material, and then compact it by rolling. As a result, the ground improvement layer 4 is formed by replacing with the ground improvement soil having a higher adhesive force and internal friction angle than the raw soil, and the connecting member 30 is embedded in the ground improvement layer 4.

This cement-based solidified material is used for temporary construction, and is mixed with about 50 to 150 kg per 1 m ^{3 of} the raw earth, stirred and rolled. In particular, in a portion where construction heavy machinery travels or works on the ground improvement soil, ground improvement is performed so that sufficient ground strength can be obtained with respect to the load of the construction heavy machinery.

In step S <b> 6, as shown in FIG. 9, the tension improving force is introduced into the connecting member 30 after the ground improvement layer 4 is formed and the passive resistance is increased in a stage before the connecting member 30 is tensioned.
Specifically, a tension bulge 40 and a hydraulic jack 41 are attached to the excavation area side of the first flank 13, and the threaded reinforcing bar 31 is pulled leftward in FIG. 8 by the hydraulic jack 41. Thus, a tension force is introduced into the threaded reinforcing bar 31 to connect the mountain retaining wall 10 and the holding pile 20 in a tensioned state. In this state, the first nut 34 is tightened to maintain the tension, and then the hydraulic jack 41 and the tension erection 40 are removed.

  At this stage, by introducing tension in advance to the connecting member 30 that connects the retaining wall 10 and the retaining pile 20 (preloading), the retaining wall 10 is moved to the excavation region side by earth pressure action after the secondary excavation. It is possible to suppress the protrusion by pulling the protruding portion that inclines toward the holding pile 20 side.

According to this embodiment, there are the following effects.
(1) The reserve pile 20 was provided in the ground on the back side of the mountain retaining wall 10, and this reserve pile 20 and the mountain retaining wall 10 were connected by the connection member 30, and tension was introduced. Therefore, even if the site on the back side of the mountain retaining wall 10 is narrow, it is only necessary to secure a space for driving the reserve pile 20 on the rear side of the mountain retaining wall 10, and the mountain retaining wall 10 can be supported. Moreover, even if the height of the retaining wall 10 is high, the retaining wall 10 can be supported because the retaining wall 10 is pulled to the back side by the connecting member 30. Further, since the structure for the mountain retaining frame is not required on the excavation region side of the mountain retaining wall 10, the excavation work is not time-consuming, and the mountain retaining frame 1 can be excavated in a short construction period. Further, the upper surface of the ground improvement layer 4 can be used as a work floor for heavy machinery.

(2) Since the ground improvement layer 4 is formed between the storage pile 20 and the mountain retaining wall 10, the ground improvement layer 4 increases the passive earth pressure Q of the storage pile 20. Therefore, even if the reserve pile 20 is pulled by the connecting member 30 and moves toward the retaining wall 10, the passive earth pressure Q of the ground improvement layer 4 resists the movement of the reserve pile 20, and the reserve pile 20 The movement to the mountain retaining wall 10 side can be prevented and the mountain retaining wall 10 can be reliably supported.
Further, the upper surface of the ground improvement layer 4 can be used as a work floor for heavy machinery.

  (3) Since the ground improvement soil of the ground improvement layer 4 is formed by adding cement-based solidifying material to the raw soil at the site, the cost can be reduced compared to the case where the ground improvement soil is carried from outside the site.

  (4) The threaded reinforcing bar 31 constituting the connecting member 30 is higher in strength and lighter than steel materials such as SS400. In addition, the threaded reinforcing bar 31 can use a ready-made fixing tool at a joint part between the threaded reinforcing bars 31 or a fixing part at the end. Therefore, as a fixing method of the connecting member 30, a high-quality tension material can be formed over the entire length without performing welding.

  (5) The tension force introduced into the connecting member 30 uses the hydraulic jack 41 that is used when installing the beam. Displacement of the mountain retaining wall 10 can be suppressed by applying a pretensioning force to the connecting member 30 to realize a preload state and causing the connecting member 30 to stretch in advance. Moreover, in the conventional construction method, the tension method using the turnbuckle used for the tie rod material is to take a slack, and the equivalent to a general preload load (about 70 to 90% of the tensile tension) assumed in the present invention is It cannot be applied to the connecting member (tie rod material).

Here, the necessary penetration length L of the reserve pile, the maximum bending moment M generated in the reserve pile, and the displacement δ of the attachment position of the tension pile (connecting member) of the reserve pile are examined.
As shown in FIG. 10, based on road earthwork, L, M, and δ are obtained by the following equation (1).

Where L: Necessary penetration length (m)
M: Maximum bending moment (kN · m)
δ: Displacement of the tension pile attachment position of the pile (m)
β: Characteristic length of pile (m ⁻¹ )
H: Horizontal force acting on the back pile (tensile force of the tensile material) (kN)
E: Young's modulus of reserve pile (kN / m ² )
I: Cross-sectional secondary moment of the pile (m ⁴ )

Where k _H : horizontal ground reaction force coefficient (kN / m ³ )
B: Pile width of the reserved pile (m)
E: Young's modulus of reserve pile (kN / m ² )
I: Cross-sectional secondary moment of the pile (m ⁴ )

From the above formulas (1) and (2), the required length L, the bending moment M generated in the retaining pile, and the displacement δ of the tension material mounting position are related to the characteristic length β of the pile, β As L becomes larger, L, M, and δ become smaller. Therefore, by increasing β, L, M, and δ are reduced, and an economical reserve pile is designed.
As a method of increasing β, by improving the ground, the ground strength on the passive side of the reserve pile is increased, and k _H and B are increased. Specifically, the construction range of ground improvement is set to the upper side of the virtual support point (region C in FIG. 10) on the passive side of the reserve pile, and when the reserve pile protrudes above the level of the tensile material, It is set as the earth covering part (area | region D in FIG. 10) of a tension material. In addition, the strength of ground improvement is determined by the cost balance of the ground pile and the ground improvement. If the ground pile protrudes above the level of the tensile material, the ground ground strength is secured to prevent heavy machinery from tipping over. To do.

[Second Embodiment]
FIG. 11 is a schematic view of a mountain retaining structure 1A according to the second embodiment of the present invention.
The present embodiment is different from the first embodiment in that the ground improvement layer 4A is formed below the connecting member 30.
That is, the ground improvement layer 4 </ b> A is formed below the connecting member 30 and around the holding pile 20. The ground improvement layer 4 </ b> A has the same configuration as the ground improvement layer 4.

  Assuming a passive shear slip fracture surface 50 of the reserve pile 20 on the pile retaining wall 10 side of the reserve pile 20, the region above the passive shear slip fracture surface 50 is a passive earth pressure region having a high shear slip fracture strength. 51. The passive earth pressure region 51 is formed by the ground improvement layers 4 and 4A.

According to this embodiment, in addition to the effects (1) to (5) described above, the following effects can be obtained.
(6) Since the passive earth pressure region 51 above the passive shear sliding fracture surface 50 has been improved over the entire area, the passive earth pressure of the reserve pile 20 further increases. The resistance due to the passive earth pressure of the ground improvement layer 4 is further increased with respect to the movement, and the mountain retaining wall 10 can be supported more reliably.

[Third Embodiment]
FIG. 12 is a schematic diagram of a mountain retaining frame 1B according to the third embodiment of the present invention.
This embodiment is different from the first embodiment in that the embankment 5 that is a heavy object is provided as a weight on the ground improvement layer 4 and in the vicinity of the reserve pile 20.

Specifically, a passive shear slip fracture surface 60 of the mountain retaining wall 10 is formed on the back side of the mountain retaining wall 10, and a region above the passive shear slip fracture surface 60 becomes a passive earth pressure region 61. .
On the ground surface, the embankment 5 is provided in a region F immediately above the passive earth pressure region 51 of the retaining pile 20 and excluding the directly above the passive earth pressure region 61 of the mountain retaining wall 10. By providing the embankment 5 in this way, the passive earth pressure around the reserve pile 20 further increases. That is, this area | region F is a range in which the passive resistance of the reserve pile 20 arises in the ground surface between the mountain retaining wall 10 and the reserve pile 20.

In the present invention, in order to increase the passive earth pressure of the retaining pile 20, the embankment 5 is installed on the upper surface of the ground improvement layer 4 around the retaining pile 20.
In the present embodiment, the embankment 5 is provided as a weight. However, the present invention is not limited to this. For example, steel plates may be laid on top of each other, and any structure may be used as long as it is a weight.

  Further, the reason for providing the embankment 5 except for the area above the passive earth pressure region 61 of the mountain retaining wall 10 is that the heavy wall is placed above the passive earth pressure area 61 of the mountain retaining wall 10 so that the mountain retaining wall 10 is activated. This is to increase the earth pressure resistance.

  In the procedure for constructing the mountain frame 1B of the present embodiment, the embankment 5 is formed after the soil 3 is backfilled on the connecting member 30 in step S6. In addition, after forming the embankment 5, it is preferable to introduce tension | tensile_strength into the connection member 30 again.

  According to this embodiment, in addition to the effects (1) to (5) described above, the following effects can be obtained.

  (7) Since it loaded on the passive earth pressure area | region 51, the passive earth pressure which acts on the soil around the reserve pile 20 further increases. Therefore, passive earth pressure resists the movement of the retaining pile 20 toward the mountain retaining wall 10 side, and the mountain retaining wall 10 can be supported more reliably.

[Fourth Embodiment]
FIG. 13 is a schematic view of a mountain retaining frame 1C according to the fourth embodiment of the present invention.
In this embodiment, the point which constructed the connection surface material 70 between the reserve piles 20 differs from 1st Embodiment.
The connecting surface material 70 is configured by arranging a plurality of H-shaped steels extending substantially horizontally above and below, and is fixed to the surface of the retaining pile 20 on the side of the retaining wall 10.

A passive shear slip fracture surface 71 of the connection surface material 70 is formed on the mountain retaining wall 10 side of the connection surface material 70. By providing this connection surface material 70, in addition to the passive earth pressure, the passive earth pressure of the connection surface material 70 acts on the storage pile 20, and the movement of the storage pile 20 to the mountain retaining wall 10 side can be prevented.
In addition, since the connection surface material 70 receives a passive earth pressure, the thing made from steel, such as a H-section steel, is higher than the cross sheet pile which is wood.

  In the procedure of constructing the mountain retaining frame 1C of the present embodiment, the connecting face material 70 is attached when attaching the second erection 22 in step S4. In step S <b> 6, it is preferable to introduce tension again to the connecting member 30 after the soil 3 is backfilled.

  According to this embodiment, in addition to the effects (1) to (5) described above, the following effects can be obtained.

  (8) In addition to the passive earth pressure of the retaining pile 20, the passive earth pressure of the connecting surface material 70 resists the movement of the retaining pile 20 toward the retaining wall 10, so that the retaining wall 10 is more reliable. Can be supported.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
In each of the above-described embodiments, the plurality of spare piles 20 are connected to each other by the second upset 22, but the present invention is not limited thereto, and when the interval between adjacent spare piles 20 is a long span, as shown in FIG. 14. In addition, the second belly 22 </ b> A may be provided on each of the storage piles 20 as a short material. When the second erection 22A is a short material, the second erection 22A can be easily attached and the material cost can be reduced.

In each embodiment, the covering member 36 that covers the threaded reinforcing bar 31 is provided. However, the present invention is not limited to this, and coarse aggregate is laid around the covering member, and the vertical load is locally applied to the threaded reinforcing bar (connecting member). In the case where the cover member 36 is not added, the covering member 36 may not be provided.
In each of the above-described embodiments, the covering member 36 has a cylindrical shape. However, the shape is not limited to this, and any shape may be used as long as a space can be secured on the side and upper side of the threaded reinforcing bar 31. For example, it is good also as a cross-sectional mountain shape which covers a coating | coated member from the top of the threaded reinforcing bar 31 from the top.

  Further, in each of the above-described embodiments, the threaded reinforcing bar 31 is used for the connecting member 30. However, when the rod-like connecting member 30 cannot be installed due to the influence of the construction place or the like, the connecting member 30 has flexibility. It is good also as a strand from PC steel.

  In the second embodiment, the ground improvement layer 4A is provided, in the third embodiment, the embankment 5 is provided on the ground improvement layer 4, and in the fourth embodiment, the connecting surface material 70 is provided between the holding piles 20. However, these configurations may be appropriately combined. For example, while providing the ground improvement layer 4A, it is good also as a structure which provides the embankment 5 on the ground improvement layer 4, and while providing the embankment 5 on the ground improvement layer 4, it is a connection surface material between the holding piles 20 mutually. 70 may be provided.

  In the third embodiment, the ground improvement layer 4 is provided, and the embankment 5 that is a heavy object is provided on the ground improvement layer 4. However, the present invention is not limited to this, and the earth surface is not subjected to ground improvement and is filled on the ground surface. Alternatively, a temporary heavy object may be provided.

1, 1A, 1B, 1C ... Yamatome frame 2 ... Ground 3 ... Soil (backfill soil)
4, 4A ... Ground improvement layer 5 ... Embankment 10 ... Mountain retaining wall 12 ... Core material 13 ... First abdomen 14 ... Lower abdomen 15 ... Upper abdomen 20 ... Reservoir pile 22, 22A ... Second abdomen 23 ... Lower flank 24 ... Upper flank 30 ... Connecting member 31 ... Threaded reinforcing bar 32 ... First fixing member 33 ... Second fixing member 34 ... First nut 35 ... Second nut 36 ... Coating member 40 ... Tension uplift 41 ... Hydraulic jack 50 ... Passing shear sliding failure surface of the retaining pile, 51 ... Passing earth pressure region acting on the retaining pile 60 ... Shearing shear sliding failure surface of the retaining wall 61 ... Activating on the retaining wall 70 ... Connection surface material 71 ... Passive shear slip fracture surface of connection surface material A ... Received shear slip failure surface by raw soil B ... Receiving shear slip failure surface by ground improved soil

Claims (4)

A mountain wall extending vertically,
Retaining piles provided on the ground opposite to the excavation area side of the retaining wall,
An abdominal erection member provided on a side surface opposite to the mountain retaining wall of the retaining pile,
A pair of connecting members that connect the mountain retaining wall and the stake pile through the erection member and introduce a tension force; and
The mountain retaining structure characterized in that the connecting member is buried in ground improvement soil.   The ground improvement soil is formed by replacing the raw soil above the lower end surface of the connecting member, or by mixing and stirring a cement-based solidifying material in the raw soil. Yamatome frame described in 1.   The ground improvement soil is formed by replacing the raw soil above the lower end surface of the connecting member and around the retaining pile, or by mixing and stirring the cement-based solidifying material in the raw soil. The mountain retaining frame according to claim 1 or 2, characterized by the above. A mountain wall extending vertically,
Retaining piles provided on the ground opposite to the excavation area side of the retaining wall,
An abdominal erection member provided on a side surface opposite to the mountain retaining wall of the retaining pile,
A pair of connecting members that connect the mountain retaining wall and the stake pile through the erection member and introduce a tension force; and
An embankment or a temporary heavy structure is provided in a range where passive resistance of the retaining pile is generated on the ground surface between the retaining wall and the retaining pile.

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