JP2012062682A - Construction method for preventing ground heaving - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ground heaving by simpler construction while securing safety from the ground heaving even during cutting down of bed to an excavation bottom surface.SOLUTION: A construction method for preventing ground heaving comprises: a step of drilling a plurality of holes 5 with a predetermined diameter, which are elongated to an artesian water layer 3, in object ground for earth retaining excavation; a step of inserting a reinforcement body 10, in which bag bodies 11 and 12 connected to piping 13 are coupled to each other by means of a tension member 14 with predetermined strength, into each hole formed by drilling; and a step of infilling a solidifying agent 30 into each of the bag bodies 11 and 12 of the reinforcing body 10, which is positioned in the artesian water layer 3 and the bottom ground 4 in the hole 5, through the piping 13, and of bringing each of the bag bodies 11 and 12 into pressure contact with the artesian water layer 3 and the bottom ground 4, which constitute a hole wall.

Description

  The present invention relates to a panel swelling prevention method, and specifically, a panel swelling prevention technique that can be carried out with simpler construction while ensuring safety against panel swelling even during panel lowering to the bottom of excavation. About.

  For example, in a site where the construction area is limited, such as urban civil engineering work, in order to effectively utilize the limited construction area, the retaining wall such as steel sheet piles and cross-sheet piles are erected, cut beams and anchors. There are many constructions involving earth retaining excavations that support excavation and support by supporting works such as. However, this soil excavation has been pointed out to generate phenomena that should be noted depending on the properties of the construction ground and groundwater. This phenomenon is a deformation phenomenon of the bottom ground such as bulging, boiling, and heaving.

  Of these, for example, in terms of padding, the water pressure of the pressured aquifer (eg sand / gravel layer) contained in the ground at the bottom of the excavation is the impermeable layer existing above the pressured aquifer. This is a phenomenon of pushing up the ground including the poorly permeable layer, and a method for coping with this phenomenon has been proposed. For example, there are countermeasures such as deepening the earth retaining or solidifying a certain depth below the bottom of excavation by ground improvement. In addition, as a method with a lower construction cost than these, a technique in which a pile is placed on the ground and the bottom surface and the pressurized aquifer are connected via a frictional force between the pile surface and the ground, or a ground An anchor is placed on the ground, and the friction force between the ground anchor surface and the ground is transmitted to the fixing plate (concrete plate) via the anchor pulling material, so that the space between the bottom ground and the aquifer is Techniques for coupling (Patent Document 1, Patent Document 2, etc.) are also considered.

JP 2000-17676 A JP 2001-182088 A

  However, in the case of the above-described technology for placing piles, if placement is performed based on the design frictional force exerted by the piles, the placement pitch tends to increase, causing board swelling between the piles, that is, hollowing out. There are concerns. On the other hand, if the pile placement pitch is reduced in order to eliminate this concern, there is a problem that the labor and cost of construction increase. In addition, in the case of deep excavation where padding is a problem, it is difficult to drive a pile using a Yatco to the depth of the bottom of the excavation, and as the excavation progresses, the upper part of the pile exposed from the excavation bottom There is also a problem that a cutting process of (example: steel material) occurs.

  In addition, in the case of the above-described technique for placing a ground anchor, it is necessary to construct a fixing board on the floor-mounted base board, and since it is at the time of excavation completion that the tensile material is fixed to this fixing board, However, there is a problem that it is not possible to cope with the swelling of the board.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a panel swelling prevention method that can be implemented with simpler construction while ensuring safety against panel swelling even during panel lowering to the bottom of excavation.

  The bulge prevention method of the present invention that solves the above-mentioned problem is a method of preventing bulge of the bottom ground during earth retaining excavation, and in the target ground of the earth excavation, a plurality of holes having a predetermined diameter extending to the pressurized water layer are cut. A step of inserting holes, a step of inserting a reinforcing body in which bags connected to each other with a tensile material having a predetermined strength are inserted into each hole formed by the drilling holes, and the pressurized water layer and Filling each of the bags of the reinforcing body located on the bottom ground with a solidifying agent through the pipe, and press-contacting the bags to the pressurized water layer forming a hole wall and the bottom ground. It is characterized by that.

  According to such a technique, each bag body expanded by a hole penetrating the pressurized water layer and the bottom ground presses and contacts the pressurized water layer and the bottom ground, and exhibits a large frictional resistance. Even if the bottom ground is subjected to the lifting pressure of the pressurized water layer, the bag body that is in pressure contact with the bottom ground is at least a tensile material from the bag body that exhibits a large frictional resistance in the pressurized water layer. The reaction force is obtained through the above, and the upward deformation of the bottom ground, that is, the board swelling is suppressed. When the layer thickness of the pressurized water layer is thin, it can be assumed that the bag body on the pressurized water layer side is arranged not only in the pressurized water layer but also across the ground layer around the pressurized water layer.

  In addition, since the contact resistance with the surrounding ground exhibited by each bag body and the strength of the tensile material that transmits the tensile force between the upper and lower bag bodies are not excessive compared to the pile, the placement pitch for the excavation area The arrangement is fine, and the concern that so-called hollows occur in a rational design can be solved. Moreover, this construction method using a bag body can prevent the panel from swelling at a lower cost than the method using a pile or the like. Further, it is not necessary to construct a fixing plate as in the conventional method using a ground anchor, and it is possible to ensure the effect of preventing board swelling even during excavation. Therefore, according to the present invention, it is possible to prevent board swelling by simpler construction while ensuring safety against board swelling even while the board is lowered to the bottom of excavation.

  Further, the ground swelling prevention method of the present invention is a construction method for preventing bottom swelling of the bottom ground in the soil excavation, and a step of drilling a plurality of holes having a predetermined diameter extending to the pressurized water layer in the ground subject to the soil excavation. And a step of inserting a reinforcing body made of a bag body having a predetermined tensile strength with a length from the pressurized water layer to the bottom ground, into each hole formed by the drilling hole, to which a pipe is connected, and Filling the bag body in the reinforcing body inserted into the hole with a solidifying agent through the pipe, and pressing the bag body against the pressurized water layer forming the hole wall and the bottom ground. Features.

  According to such a technique, the integrated bag body expanded by the hole penetrating the pressurized water layer and the bottom ground presses and adheres to the ground from the pressurized water layer to the bottom ground, and has a large frictional resistance. Demonstrate. In addition, the bag body itself has an appropriate tensile strength, and even if the bottom ground receives the lifting pressure of the pressurized water layer and tries to swell, the portion of the integral bag that is in pressure contact with the bottom ground The reaction force is obtained at least from the portion exhibiting a large frictional resistance force in the pressurized water layer, and the upward deformation of the bottom ground, that is, the board swelling is suppressed. In addition, when the layer thickness of a pressurized water layer is thin, the situation which arrange | positions the bag body by the side of a pressurized water layer straddling not only a pressurized water layer but the ground layer around a pressurized water layer can also be assumed.

  In addition, since the contact resistance with the surrounding ground that each bag body exerts and the strength of the bag body itself that transmits the tensile force are not excessive, the placement pitch for the excavation area is finely arranged, and the rational design No so-called hollow out occurs. Moreover, this construction method using a bag body can prevent the panel from swelling at a lower cost than the method using a pile or the like. Further, it is not necessary to construct a fixing plate as in the conventional method using a ground anchor, and it is possible to ensure safety against board swelling even during excavation. Therefore, according to the present invention, it is possible to prevent board swelling by simpler construction while ensuring safety against board swelling even while the board is lowered to the bottom of excavation.

  In the panel swelling prevention method, a rod-shaped guide member is detachably attached to the reinforcement body, and the guide body is lowered in the hole to insert the reinforcement body into the hole, and the bag body After the solidifying agent is filled in and the bag body is pressed against the pressurized water layer and the bottom ground, a step of removing the guide material from the reinforcing body may be included.

  According to this, it becomes possible to reliably feed the flexible bag body to the pressurized water layer in the limited space in the hole wall, and the construction accuracy can be improved. Further, by obtaining a reaction force on the bag body filled with the solidifying agent and pressed against the surrounding ground, the guide material can be easily removed and the workability is good. In addition, since the guide material is not exposed from the bottom of the excavation as the earth retaining excavation proceeds, there is no problem in excavation operation by the excavating machine or the like.

Moreover, in the said board swelling prevention construction method, the said guide material is a pipe body provided with a discharge outlet in the position of the said bag body, and it is good also as what also serves as the said piping for solidification agent filling.
According to this, the step of feeding the bag body to the pressurized water layer and the step of filling the bag body with the solidifying agent can be performed using the guide material, and the construction efficiency and cost are improved. You can do it.

  In the present invention described above, even if the reinforcing body is exposed from the bottom of the excavation as the soil excavation progresses, the bag body made of fibers and the solidifying agent (eg, grout agent) filled therein are: Since there is no hindrance to the excavation operation by the excavating machine, the construction efficiency of the entire soil excavation is good.

  In addition, the object to be filled with a solidifying agent such as mortar or grout is a bag body, not a space in the hole wall where the ground where leakage due to infiltration is a concern is exposed, and the amount of solidifying agent injected into the bag body can be controlled. It can be done reliably. That is, appropriate expansion of the bag body and press contact with the surrounding ground can be ensured. Naturally, even if there is a groundwater flow in the ground around the bag body or the hole wall collapses, there is no dissipation of the grout filled in the bag body.

  The bag body is a flexible member, and is reinforced with high tensile strength such as aramid fiber or carbon fiber on a woven or non-woven fabric made of hemp or synthetic fiber having flexibility and wear resistance. What mixed the fiber etc. can be used. Further, the bag body is subjected to adjustment of the mesh and watertight processing so that moisture does not easily ooze out.

  According to the present invention, it is possible to prevent board swelling even during construction of earth retaining excavation under good efficiency and cost.

It is a figure which shows the application example 1 of the board swelling prevention construction method in this embodiment. It is a figure which shows the structural examples, such as a bag body in this embodiment. It is a flowchart which shows the procedure example 1 of the board swelling prevention construction method in this embodiment. It is a figure which shows the example 2 of application of the board swelling prevention construction method in this embodiment. It is a flowchart which shows the procedure example 2 of the board swelling prevention construction method in this embodiment. It is a figure which shows the example 3 of application of the board swelling prevention construction method in this embodiment.

--- Application example 1 ---
Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing an application example 1 of a board swelling prevention method in the present embodiment, FIG. 2 is a diagram showing a structural example of a bag body and the like in the present embodiment, and FIG. 3 is a procedure of a board swelling prevention construction method in the present embodiment. 10 is a flowchart showing Example 1. FIG. In the earth excavation work to which the panel swelling prevention method is applied, for example, it is assumed that the earth retaining wall 1 is formed by carrying out support by placing steel sheet piles, raising uprights, and cutting beams. The ground surrounded by the retaining wall 1 is mainly composed of, for example, a gravel layer 3 as a pressurized water layer, a clay layer 4 as a soft hardly permeable layer, and a sandy soil layer 6 in order from the lower layer. 3, the tip of the retaining wall 1 has reached. In addition, among the ground surrounded by the retaining wall 1, a part (or all) of the sandy soil layer 6 is the target ground 2 for the soil excavation.

  If the sandy soil layer 6 which is the target ground 2 is dug as it is and the weight above the clay layer 4 decreases, the pressure of the pressurized water in the gravel layer 3 will exceed the weight of the portion above the clay layer 4. It is assumed that there is a concern that a board swelling phenomenon occurs in which a portion above the clay layer 4 is pushed upward.

  Therefore, the board swelling prevention method of the present embodiment is applied, and in the target ground 2, first, a plurality of holes 5 having a predetermined diameter extending to the gravel layer as the pressurized water layer are drilled (s100). The diameter of the hole 5 is smaller than the diameter shown when the bags 11 and 12 of the reinforcing body 10 to be inserted into the hole 5 are expanded. Therefore, the bag bodies 11 and 12 which are going to expand | swell in the hole 5 by filling with solidifying agents 30, such as grout, can fully press-contact with the surrounding ground, and can exhibit a required frictional resistance. The pile used in the prior art has a diameter of about 600 mm, for example, but the diameter of the hole 5 in the present embodiment can be 100 to 140 mm, and the diameter of the bag bodies 11 and 12 can be about 150 to 300 mm.

  Further, the drilling length of the hole 5 is also determined so that the bag 11 is arranged in the gravel layer 3 at least for the fixing length. Further, the design related to the installation of the reinforcing body 10 per unit area on the bottom of the excavation based on the stress that can be borne by one reinforcing body 10 and the lift of the panel swelling generated from the pressurized water layer is, for example, as follows: To be done.

The lift generated on the upper surface of the pressurized water layer is “A”, the weight of the clot above the pressurized water layer is “B”, the length of the reinforcing body 10 above the pressurized water layer is “l ₁ ”, and the reinforcement Let the frictional force with the hole 5 per unit length in the body 10 be “c”. In this case, if the value of “(A−B) / (c × l ₁ )” is calculated, the number of sets of bags necessary to bear the stress of board swelling, that is, the number of drilled holes 5 is obtained. It is done. Further, when the frictional force per unit length between the hole 5 and the reinforcing body 10 below the pressurized water layer is “d”, the value of “(c × l ₁ ) / d” is calculated. The necessary contact length l ₂ that the bag body below the pressurized water layer should secure against the wall surface of the hole 5, that is, the length of the hole 5 (the length of the hole 5 in the gravel layer 3 in the ground) is obtained. In addition, since the gravel layer 3 is in the lowest layer of the ground, if the length of the hole 5 in the gravel layer 3 is determined as described above, the sand gravel layer 3 naturally penetrates the clay layer 4 and the sandy soil layer 6. The length up to the bottom of the hole 5 is the length of the hole 5. Of course, the adhesion force (friction force) between the solidifying agent 30 filled in the bag body and the tensile material 14 inside the bag body and the strength of the tensile material 14 are the above-mentioned value “c × l ₁ ”, that is, 1 It must be greater than the frictional force that can occur between the wall surface of the book hole 5 and the bag. Moreover, it goes without saying that an appropriate safety factor is taken into consideration in these designs.

  Next, the reinforcing body 10 is inserted into the drilled hole 5, the bag body 11 is disposed in the gravel layer 3, and the bag body 12 is disposed in the clay layer 4 (s101). The reinforcing body 10 has a structure in which bag bodies 11 and 12 connected to a pipe 13 are connected to each other by a tensile material 14 having a predetermined strength. The bag body 11 expands in the gravel layer 3, and the bag body 12 expands in the clay layer 4. Moreover, the tension | tensile_strength material 14 is comprised by the member provided with predetermined | prescribed tensile strength, such as a steel bar and steel wire, for example, is arrange | positioned at the clay layer 4 from the bottom part of the bag 11 arrange | positioned at the gravel layer 3. FIG. It penetrates to the upper part of the bag body 12. The tensile strength of the tensile material 14 is such that the bag 12 in pressure contact with the clay layer 4 obtains a reaction force from the bag 11 in pressure contact with the gravel layer 3 and resists the bulging stress of the clay layer 4. Depending on. Moreover, the piping 13 is connected to each of the bag bodies 11 and 12, for example, and provides the bag bodies 11 and 12 with a solidifying agent 30 such as mortar or grout sent from a predetermined solidifying agent supply device 40. It becomes a pipeline to do. If an appropriate resin pipe such as a vinyl chloride pipe is applied as the pipe 13, even if it is exposed from the floor base plate during earth retaining excavation, it can be easily removed by a heavy excavator or the like, which is preferable without causing any trouble in excavation.

  In inserting the reinforcing body 10 into the hole 5, the rod-shaped guide member 50 is detachably attached to, for example, the tension member 14 or the bag body 12 of the reinforcing body 10, and the guide member 50 is lowered in the hole 5. Thus, it is preferable to insert the reinforcing body 10 into the hole 5. As a technique for detachably attaching the guide member 50 to the tension member 14 and the bag body 12 of the reinforcing body 10, for example, the following technique can be considered. As shown in FIG. 2, for example, a male screw 51 is cut at a portion of the upper end of the tension member 14 protruding from the upper portion of the bag body, and a lower end of the guide member 50 is provided with a cap nut 53 with a female screw 52 cut. When the reinforcing body 10 is inserted into the hole 5, the cap nut 53 at the lower end of the guide member is screwed together with the male screw 51 at the upper end of the tensile member, while the guide member 50 is removed from the reinforcing member 10. The guide member 50 is rotated by obtaining a reaction force on the bag bodies 11, 12 and the like that are in pressure contact with the surrounding ground, and the cap nut 53 at the lower end thereof is unscrewed from the male screw 51 at the upper part of the tension member body. Alternatively, an arm-shaped gripping mechanism is provided at the lower end of the guide member 50, and when the reinforcing body 10 is inserted into the hole 5, the gripping mechanism at the lower end of the guide member grips the tension member 14 and is integrated. When removing 50 from the reinforcing body 10, there is also a method in which the gripping mechanism at the lower end of the guide material releases the gripping material 14 and separates it.

  Subsequently, a solidifying agent 30 such as mortar or grout is filled into the bag 11 of the reinforcing body 10 located in the gravel layer 3 in the hole 5 through a pipe 13 (s102), and the gravel layer 3 forming the hole wall is filled with the bag. 11 is pressed (s103). Similarly, the bag 12 located in the clay layer 4 in the hole 5 is filled with a solidifying agent 30 such as mortar or grout through the pipe 13 (s104), and the bag 12 is pressed against the clay layer 4 forming the hole wall. (S105). By such treatment, the bags 11 and 12 expanded in the holes 5 penetrating the gravel layer 3 which is the pressurized water layer and the clay layer 4 which is the bottom ground press the sand gravel layer 3 and the clay layer 4, respectively. A large frictional resistance will be exhibited.

  In addition, the object to be filled with the solidifying agent 30 such as mortar or grout is not the space in the hole wall in which the ground where leakage due to permeation or the like is a concern is exposed but the bag body 11, 12. The amount of solidifying agent injected can be controlled reliably. That is, appropriate expansion of the bag bodies 11 and 12 and press contact with the surrounding ground can be ensured. Naturally, even if a groundwater flow exists in the ground around the bag body or the hole wall collapses, the solidifying agent 30 filled in the bag bodies 11 and 12 does not dissipate.

  As shown in FIG. 2, the connection portion of the pipe 13 in the bag body is provided with a box-shaped check valve mechanism 15 that includes the opening at the tip of the pipe 13, and the solidifying agent filled in the bag body. It is preferable if 30 is considered so as not to flow backward to the solidifying agent supply device side. The check valve mechanism 15 includes, for example, a stopper 16 having an upwardly convex conical shape and an appropriate opening 16a at the top, and a surface shape and size that can completely close the opening of the stopper 16. The structure which consists of the mesh-shaped board | plate material 18 which does not inhibit passage of the solidification agent 30, ensuring the movable space of the movable body 17 between the movable body 17 and the stopper 16 is mention | raise | lifted. The solidifying agent 30 that has flowed into the check valve mechanism 15 inside the bag body from the opening of the pipe 13 passes through the opening 16a of the stopper 16 (pressing downward if there is a movable body 17), and the mesh of the mesh plate 18 It passes through the opening and is filled into the bag body as it is. On the other hand, when the solidifying agent 30 filling the empty space in the bag passes through the mesh plate 18 and flows into the check valve mechanism 15, the movable body 17 that is moved upward by this inflow pressure has a conical shape. The stopper 16 is pressed against the top opening 16a while moving upward on the surface of the stopper 16, and the opening 16a is closed. That is, the rise of the solidifying agent 30 stops at this point, and the backflow to the solidifying agent supply measure side is suppressed. Although FIG. 2 illustrates the check valve mechanism 15 installed in the bag body 12, the check valve mechanism 15 is similarly installed in the bag body 11 and performs the same function as described above.

  After the bags 11 and 12 are filled with the solidifying agent 30 and the bags 11 and 12 are pressed against the gravel layer 3 and the clay layer 4, the guide member 50 is removed from the reinforcing body 10 (s106). By obtaining a reaction force on the bags 11 and 12 filled with the solidifying agent 30 and pressed against the surrounding ground, the guide member 50 can be easily removed and the workability is also good. Moreover, since the guide material 50 is not exposed from the bottom of the excavation as the earth excavation proceeds, there is no problem in excavation operation by the excavating machine or the like.

  According to the present embodiment as described above, the bags 11 and 12 expanded in the holes 5 penetrating the gravel layer 3 that is the pressurized water layer and the clay layer 4 that is the bottom ground are respectively connected to the gravel layer 3 and the clay layer 4. Presses and adheres and exhibits great frictional resistance. Even if the upper part of the clay layer 4 that is the bottom ground is subjected to the lifting pressure of the gravel layer 3 that is the pressurized water layer, the bag 12 that is in pressure contact with the clay layer 4 has a large frictional resistance in the gravel layer 3. A reaction force is obtained from the bag body 11 exhibiting the above through the tension member 14, and the upward deformation of the clay layer 4, that is, the board swelling is suppressed.

  Moreover, since the contact resistance with the surrounding ground which each bag body 11 and 12 etc. exhibit and the intensity | strength of a tension material are not excessive compared with a pile, the placement pitch with respect to an excavation area becomes a fine arrangement | positioning, and rational In a simple design, a state in which so-called hollows do not occur can be realized. Moreover, this construction method using the bag bodies 11 and 12 can aim at prevention of panel swelling at a lower cost than the method using a pile or the like. Further, it is not necessary to construct a fixing plate as in the conventional method using a ground anchor, and it is possible to function as a measure for preventing panel swelling during excavation.

  In addition, it is good also as filling in the area | region 19 between the bag body 11 and the bag body 12 in a hole wall with filling materials, such as bentonite, grout, and sand, and preparing for a hole wall collapse.

  Moreover, as shown in the upper right of FIG. 1, you may employ | adopt the structure which has a plurality of sets of bag bodies as the reinforcing body 10 at the top and bottom. Or, for example, one bag body 11 is arranged in the pressurized water layer, one bag body 12 is arranged in each of the hardly water-permeable layer and the ground layer thereabove, and the reinforcing body 10 is composed of a total of three bag bodies. Also good. In any case, the arrangement and number of bags may be set according to the situation.

--- Application example 2 ---
Then, unlike the application example 1 in which the bag body in the reinforcing body 10 is separated for each layer of the pressurized water layer and the bottom ground, an example in which the layers are integrated across the layers will be described. FIG. 4 is a diagram showing an application example 2 of the board swelling prevention method in the present embodiment, and FIG. 5 is a flowchart showing a procedure example 2 of the board swelling prevention construction method in the present embodiment. In this case, the bag body 100 is connected to the pipe 13 for filling with the solidifying agent 30, and has a predetermined tensile strength with a length from the gravel layer 3 as the pressurized water layer to the clay layer 4 as the bottom ground. It becomes. The tensile strength of the bag body 100 is determined when the portion 101 of the bag body 100 that is in pressure contact with the clay layer 4 obtains a reaction force from the portion 102 that is in pressure contact with the gravel layer 3 and counters the bulging stress of the clay layer 4. It will be according to the pull of the. Since the bag body 100 in this application example does not need to use the tensile material 14 as compared with the application example 1, the structure of the bag body 100, that is, the reinforcement body 10, is further simplified, and the handling of the reinforcement body 10 is simple. It will be something.

  The drilling length of the hole 5 is also determined so that the bag body 100 is arranged in the gravel layer 3 at least for the fixing length. Moreover, the design regarding the installation of the bag body 100 required per unit area in the bottom of excavation based on the stress that can be borne by one bag body 100 and the lift of the panel swelling generated from the pressurized water layer is, for example, as follows: To be done.

The lift generated on the upper surface of the pressurized water layer is “A”, the weight of the soil mass above the pressurized water layer is “B”, the length of the bag body 100 above the pressurized water layer is “l ₁ ”, and the bag The frictional force with the hole 5 per unit length in the body 100 is defined as “c”. In this case, if the value of “(A−B) / (c × l ₁ )” is calculated, the number of sets of bags 100 necessary to bear the swelling stress, that is, the number of drilled holes 5 is obtained. can get. Further, if the frictional force per unit length between the hole 5 and the bag body 100 below the pressurized water layer is “d”, the value of “(c × l ₁ ) / d” is calculated. The required contact length l ₂ that the bag body 100 should secure against the wall surface of the hole 5, that is, the length of the hole 5 (the length of the hole 5 in the gravel layer 3 in the ground) is obtained. In addition, since the gravel layer 3 is in the lowest layer of the ground, if the length of the hole 5 in the gravel layer 3 is determined as described above, the sand gravel layer 3 naturally penetrates the clay layer 4 and the sandy soil layer 6. The length up to the bottom of the hole 5 is the length of the hole 5. Needless to say, an appropriate safety factor is considered in these designs.

  Further, in this example, the steps of drilling the hole 5 (s200) and inserting the reinforcing body 10 into the hole 5 (s201) are the same as in the first application example, and the description thereof is omitted. Here, the bag 100 in the reinforcing body 10 inserted into the hole 5 is filled with the solidifying agent 30 through the pipe 13 (s202), and the bag 100 is pressed against the gravel layer 3 and the clay layer 4 forming the hole wall. (S203).

  According to such an application example, the integral bag body 100 inflated in the hole 5 penetrating the gravel layer 3 and the clay layer 4 presses the ground from the gravel layer 3 to the clay layer 4, and is closely attached. Demonstrate friction resistance. Further, the bag body itself has an appropriate tensile strength, and even if the clay layer 4 is subjected to the lifting pressure of the gravel layer 3 and tries to swell, it is in pressure contact with the clay layer 4 in the integral bag body 100. The part 101 obtains a reaction force from the part 102 exhibiting a large frictional resistance force at least in the gravel layer 3 and suppresses upward deformation of the clay layer 4, that is, board swelling.

  In addition, as illustrated in FIG. 6A, the guide member 50 is a pipe body that has a discharge port 55 near its lower end and extends to the bottom of the bag body, and also serves as the pipe 13 for filling the solidifying agent. It may be. According to this, the step of feeding the reinforcing body 10 to the depth of the gravel layer 3 as the pressurized water layer and the step of filling the bag body 100 with the solidifying agent 30 can be performed using the guide material 50. It is possible to prevent the panel from swelling more efficiently. If an appropriate resin member such as a vinyl chloride pipe is applied as the guide member 50, it is left in the soil as it is together with the bag body 100 and can be easily removed with a heavy excavator or the like even if it is exposed from the floor base plate during earth retaining excavation. It is suitable because it does not hinder excavation.

  Moreover, as shown in FIG.6 (b), you may make the guide material 50 serve as the piping 13 to the bag body upper part. In this case, for example, the female screw 52 at the lower end of the guide member and the female screw 51 of the connecting jig 60 attached to the bag body are connected by screwing. The solidifying agent 30 supplied from the solidifying agent supply device 40 passes through the inner space of the guide member 50 as the pipe 13 and flows into the bag body from the lower end via the connection jig 60. Therefore, it is desirable that a check valve mechanism 15 (similar to Application Example 1 described above) is provided around the connection jig in the bag body. If such a check valve mechanism 15 is provided, the backflow of the solidifying agent 30 filled into the bag body to the solidifying agent supply device side can be suppressed.

  As described above, according to the present embodiment, it is possible to prevent board swelling by simpler construction while ensuring safety against board swelling even when the board is lowered to the bottom of excavation. Moreover, in this embodiment, when the tension | tensile_strength which resists lifting pressure cannot be shared only with the intensity | strength of a bag body, the form which installs a tension material inside a bag body is also considered.

  As mentioned above, although embodiment of this invention was described concretely based on the embodiment, it is not limited to this and can be variously changed in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 Earth retaining wall 2 Target ground 3 Pressurized water layer, gravel layer 4 Bottom ground, clay layer 5 Hole 10 Reinforcement body 11, 12 Bag body 13 Pipe 14 Tensile material 15 Check valve mechanism 16 Stopper 16a Stopper opening 17 Movable body 18 Mesh-like plate material 30 Solidifying agent 40 Solidifying agent supply device 50 Guide material 60 Jig 100 for connection Bag body

Claims (4)

It is a construction method that prevents the swelling of the bottom ground in earth retaining excavation,
A step of drilling a plurality of holes having a predetermined diameter extending to the pressurized water layer in the target ground for earth retaining excavation;
Inserting a reinforcing body in which bags connected to each other are connected to each other with a tensile material having a predetermined strength into each hole formed by the drilling holes;
In each of the holes, the reinforcing body located in the pressurized water layer and the bottom ground is filled with a solidifying agent through the pipe, and each bag is formed in the pressurized water layer and the bottom ground forming a hole wall. A step of pressing the body,
The board swelling prevention method characterized by including. It is a construction method that prevents the swelling of the bottom ground in earth retaining excavation,
A step of drilling a plurality of holes having a predetermined diameter extending to the pressurized water layer in the target ground for earth retaining excavation;
A step of inserting a reinforcing body made of a bag body having a predetermined tensile strength with a length from the pressurized water layer to the bottom ground, into each hole formed by the drilling holes, to which piping is connected;
Filling the bag body in the reinforcing body inserted into the hole with a solidifying agent through the pipe, and pressing the bag body against the pressurized water layer and the bottom ground forming a hole wall;
The board swelling prevention method characterized by including. In claim 1 or 2,
A rod-shaped guide material is detachably attached to the reinforcement body, and the guide body is lowered in the hole to insert the reinforcement body into the hole.
After the bag body is filled with a solidifying agent and the bag body is pressure-contacted to the pressurized water layer and the bottom ground, it includes a step of removing the guide material from the reinforcing body. Construction method. In claim 3,
The board swelling prevention method characterized in that the guide material is a pipe body having a discharge port at the position of the bag body, and also serves as the pipe for filling the solidifying agent.

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