JP2005061021A - Ground reinforcing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ground reinforcing method for easily improving the ground by performing horizontal leveling excavation of the surface layer part of the natural ground, and driving anchor members therein and straining them in improving or reinforcing the natural ground. <P>SOLUTION: Horizonal leveling excavation of the surface layer part is performed. Multilayer banking layers 4, flat or almost flat net-like or grid-like reinforcing members 5 with a large friction coefficient and high tensile strength interposed between the banking layers, and an upper plate 3 of high rigidity disposed on the uppermost banking layer, are disposed on the surface layer part to construct a reinforced soil skeleton. The anchor members 6 are then provided passing through the upper plate 3, reinforcing members 5, banking layers 4 and a deposit layer 21 at the lower part of the banking layer to reach the support ground 22, and the anchor members are strained to apply compressive force not only to the banking layers but also to the deposit layer. A load lead-in reinforced soil foundation enlarged from the reinforced soil skeleton is thereby constituted to reinforce the ground. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for improving or reinforcing natural ground, and more particularly, to a ground reinforcing method in which an anchor member is driven and tensioned.

  Conventionally, when improving or reinforcing the ground, a replacement method that removes defective soil and replaces it with good quality soil, a forced ground agitation improvement method that improves the ground using a solidifying material, or a chemical injection A ground injection method for ground improvement, a preloading method for forming a fill on the ground and increasing the total pressure applied to the ground in advance to promote consolidation settlement of the foundation ground and to increase the strength are adopted.

  In the replacement method, it is necessary to remove and dispose of defective soil. In the forced ground agitation improvement method, heavy metals such as cement-based solidification material are mixed into the ground, and there is a concern about soil contamination. Moreover, in the ground injection method, there is anxiety such as pollution due to the chemicals to be injected. Furthermore, in the preloading method, it is necessary to leave the soil for a certain period after being filled with the embankment on the ground, and then remove and unload the embankment, which takes time and labor to remove and remove the embankment material. Also, the construction period is longer.

For this purpose, a method of forming a foundation structure to support upper structures such as abutments and piers by laminating multiple embankment layers while rolling and compressing the entire embankment layer with anchors has been released. . (For example, see Patent Document 1)
The foundation construction described in Patent Document 1 is a flat structure having a large friction coefficient and a high tensile strength between each embankment layer by stacking a plurality of embankment layers of a certain thickness on a highly rigid foundation support made of steel plate or the like. Alternatively, it is a foundation structure with a substantially flat reinforcing material interposed therebetween, and further, a plurality of anchors penetrating the multi-layered embankment layer and the reinforcing material are attached, tightened, and each embankment layer and the reinforcing material Is an integrated configuration.

In addition, a reinforced soil structure that has been constructed so that the foundation structure constructed by tightening the embankment layer is equipped with a loosening prevention mechanism at the top of the anchor so that constant prestress is continuously maintained at all times has already been released. ing. (For example, see Patent Document 2)
In addition, a fastening device having a configuration in which a number of disc springs are stacked in order to impart a certain tension to a reinforcing bar such as an anchor and prevent loosening has been disclosed. (For example, see Patent Document 3)
Japanese Patent No. 2597116 (page 1-5, FIG. 1) JP 2002-146793 A (page 1-12, FIG. 1) JP-A-2002-339356 (page 1-7, FIG. 1)

  However, in the ground improvement method using concrete or cement-based solidification material, it is necessary to dug up the soft ground, add the solidification material and compact it, and the period of time for hardening becomes long, and large construction heavy machinery It is necessary, and the construction is long and difficult.

  On the other hand, the foundation construction body using the reinforced soil described in Patent Document 1 is obtained by tightening an embankment layer laminated between a high-rigidity base support and a high-rigidity floor slab to be a top plate from above and below. It is the structure which adds stress, Comprising: Tensile prestress is introduce | transduced into the reinforcing material itself laid between each embankment layer. As a result, the pre-stress constitutes an integrated foundation structure in which the entire stacked embankment layer maintains high rigidity and strength.

  However, it is a configuration in which the embankment layer is stacked on a highly rigid foundation support, and when a solid rock is used as the foundation support, it is necessary to excavate until the rock is exposed, In the case shown in FIG. 10 in which the embankment layer is constructed on the inclined surface, in addition to the anchor member 6 in the vertical direction, it is necessary to provide an anchor member 6C in the oblique direction substantially orthogonal to the inclined surface.

  Further, the reinforced earth structure described in Patent Document 2 requires a complicated loosening prevention mechanism in order to always apply a constant tension (prestress).

  An object of the present invention is to provide a ground reinforcement construction method that has both the characteristics of a preloading construction method and a reinforced earth construction method and that can further reinforce the ground with a small construction scale and a short construction period. .

  In order to achieve the above object, according to the first aspect of the present invention, the surface layer portion is leveled and excavated, and a highly rigid upper board is disposed thereon, and the upper board and the lower part of the upper board are arranged. An anchor member that penetrates the deposited layer and reaches the support ground is provided, and a first nut member is screwed into a screw portion formed at the upper end portion of the anchor member, and the anchor member is tightened and tightened to deposit. It is characterized in that the ground is reinforced by increasing the strength of the sedimentary layer by applying a compressive force to the layer.

  According to the invention according to claim 1 having the above-described configuration, the sedimentary layer at the lower part of the upper board can be reinforced by simply installing the upper board on the surface layer that has been leveled and excavated, and driving the anchor member up and tightening. And the ground can be reinforced.

  In the invention according to claim 2, the surface layer portion is leveled and excavated, and a multi-layered embankment layer and a flat or substantially flat net shape having a large friction coefficient and tensile strength interposed between the embankment layers and each embankment layer, After the lattice-shaped reinforcing material and a high rigidity upper board are arranged on the uppermost embankment layer to form a reinforcing earthen body, the upper board, the reinforcing material, the embankment layer, and a deposited layer below the embankment layer The embankment layer is provided by providing an anchor member penetrating through the support ground, screwing a first nut member into a screw portion formed at the upper end portion of the anchor member, tightening the anchor member and tensioning In addition to forming a reinforced soil pseudo frame by applying a compressive force to the sedimentary layer, the load introduction reinforced soil foundation is configured to reinforce the ground by expanding the reinforced soil body. It is said.

  According to the invention according to claim 2 having the above-described configuration, a multi-layered embankment layer is formed on the surface layer portion that has been leveled and excavated, and the upper board is placed and the anchor member is supported through the deposition layer. By constructing a load-introducing reinforced soil foundation by driving into the ground, it is possible to construct an apparently large foundation ground by using the reinforced soil foundation as an integral part of the deposited layer.

  The invention according to claim 3 excavates from the surface layer portion to the supporting ground, cuts the supporting ground to create a flat portion, and laminates the flat portion while rolling back-filled soil or high-quality soil. And a multi-layered embankment layer, a flat or substantially flat mesh-like or lattice-like reinforcing material having a large friction coefficient and tensile strength, and a high rigidity on the top embankment layer. After the upper board is disposed and the reinforced earth body is formed, an anchor member that penetrates through the rolling laminate of the upper board, the reinforcing material, the embankment layer, and the lower part of the embankment layer to reach the support ground is provided, The first nut member is screwed into the threaded portion formed at the upper end portion of the anchor member, and the anchor member is tightened and tensioned, so that not only the embankment layer but also the rolling lamination portion is compressed. A reinforced soil pseudo-body is formed by acting, It constitutes a remote enlarged load introduced reinforced soil foundation was being characterized in that it is configured to reinforce the ground.

  According to the invention according to claim 3 having the above-described configuration, it is possible to provide an effective load-introducing reinforced soil foundation even in a natural ground with inclined support ground.

  According to a fourth aspect of the present invention, when the first nut member is screwed into the threaded portion formed at the upper end portion of the anchor member, and the anchor member is tightened and tensioned, the hollow cylindrical inner metal fitting and the casing It is characterized in that it is configured to be tensioned via a fastening member using a shear rubber spring material having a structure in which a rubber-like elastic body layer is sandwiched between the metal fittings as a pressurizing means.

  According to the invention which concerns on Claim 4 which has said structure, it only follows tension | tensile_strength of a embankment, foundation ground subsidence | elongation, and expansion | extension of an anchor member only by tensioning an anchor member via the shear rubber spring material of a single part. The tension can be given.

  According to a fifth aspect of the present invention, the fastening member further includes a second nut member and a spring spring material that biases the second nut member in the tightening direction in addition to the pressurizing means. It has the means.

  According to the invention which concerns on Claim 5 which has said structure, constant tension force can always be stably provided over a long period of time.

  According to a sixth aspect of the present invention, a worm wheel is formed on the outer edge of the second nut member, a worm that engages with the worm wheel is disposed, and the second nut member is tightened in the tightening direction. It is characterized by being configured to be urged to rotate.

  According to the invention which concerns on Claim 6 which has said structure, loosening of a 2nd nut member can be prevented further reliably.

  The invention according to claim 7 is configured to be tensioned via a fastening member formed of a corrugated plate made of spring steel, instead of the fastening member using the shear rubber spring material according to claim 4 as a pressurizing means. It is characterized by that.

  According to the invention according to claim 7 having the above-described configuration, it is possible to always apply a constant tension force only by tensioning the anchor member via the corrugated plate, and to prevent the tension force from loosening. it can.

  As described above, according to the present invention, the surface layer portion of the natural ground is leveled and excavated, the upper plate is placed, and the anchor member is driven through the deposited layer until it reaches the support ground. The deposited layer that has been driven in can be used as a reinforced soil pseudo-enclosure, and the ground can be reinforced. In addition, when an embankment layer is formed on the excavated ground and a load-introducing reinforced soil foundation is constructed, the piled-up sedimentary layer is also used as an integral reinforced soil foundation, so that an apparently larger reinforced foundation ground can be obtained. Can be built.

  Therefore, it is also a ground reinforcement method for constructing a large load-introducing reinforced soil foundation by small-scale civil engineering work, and it is suitable for narrow terrain such as mountainous areas, and it can achieve environmentally friendly and low cost reduction. is there.

  Furthermore, since the lower sedimentary layer is tightened simultaneously with the reinforcing soil constituting the foundation and integrated with the surrounding soil, a stable large-scale foundation ground can be obtained.

  When improving or reinforcing natural ground, leveling the surface layer and excavating it, placing the upper plate and driving the anchor member to the supporting ground, or constructing a relatively small load-introducing reinforced soil foundation In this way, the anchor member is driven to the supporting ground, so that the ground reinforcement method can be constructed easily and in a short period of time.

  Hereinafter, a first embodiment of the ground reinforcement method according to the present invention will be described with reference to FIGS.

  FIG. 1 is a sectional view showing a first embodiment of a load-introducing reinforced soil foundation according to the present invention. FIG. 2 is a schematic explanatory view showing the effectiveness of the load-introducing reinforced soil foundation according to the present invention. FIG. 3 is a schematic explanatory view showing an embodiment for preventing slope slip, (a) showing a ground reinforcement method using a load-introducing reinforcing soil foundation, and (b) showing a ground reinforcement method using an upper plate and an anchor member. ing. FIG. 4 shows an example in which the load-introducing reinforced soil foundation according to the present invention is arranged in a river channel, where (a) shows a transmission type dam and (b) shows a diversion bank. FIG. 5 is a sectional view showing a reinforced soil foundation by a conventional construction method. FIG. 6 is a cross-sectional view showing the structure of the upper end portion of the anchor member provided with the fastening member and the loosening prevention means, and FIG. 7 is a perspective view showing the second loosening prevention means provided with the worm gear. FIG. 8 is a schematic explanatory view showing a configuration of an upper end portion of an anchor member provided with a corrugated plate as a fastening member.

  As shown in FIG. 5, the conventional load-introducing reinforced soil foundation 10 is constructed by providing a large excavation part 20B on the sedimentary layer 21 of the natural ground, and the bottom board 2 is installed after the bottom leveling of the excavation part 20B. Then, the anchor member 6 is mounted and fixed. Next, the foundation is constructed. In this foundation construction, the reinforcing material 5 is laid between the multi-layered embankment layers (4a, 4b, 4c, 4d), and the embankment layer 4 is constructed by rolling and compacting sequentially. Is. Further, the upper board 3 is installed and the nut member 7 is screwed into the threaded portion formed at the upper end of the anchor member 6 protruding above the upper board 3 to tighten the anchor member 6, The embankment layer 4 sandwiched between the boards 3 is integrally compressed to form a reinforced earth body, and a load-introducing reinforced soil foundation 10 is constructed. That is, the load-introducing reinforced soil foundation 10 according to the conventional method is a foundation having the same size as a reinforced earth body in which the bottom board 2, the upper board 3, and the embankment layer 4 are integrally tightened.

  More specifically, the foundation 10 is formed by inserting and fixing an anchor member 6 made of PC steel bar into a perforated hole provided in a highly rigid bottom plate 2 such as a steel plate, and then forming a bottom embankment 4d. Then, the reinforcing material 5 is laid while being tamped with a compactor, and the next embankment 4c is formed thereon and further reinforced, and a new reinforcing material 5 is laid, and the embankment 4b, the reinforcing material 5, and the uppermost embankment. The layers 4a are stacked one after another, and finally a highly rigid upper board 3 is installed.

  At this time, a flat or substantially flat net-like or lattice-like reinforcing material (geotextile, expanded metal, etc.) having a large friction coefficient and tensile strength is adopted as the reinforcing material 5 while being interposed between multiple thin embankment layers. In this configuration, the bases 10 having a predetermined thickness are sequentially stacked until they are formed. At this time, when the embankment layer 4 is configured to use the remaining soil excavated from the excavation unit 20B, no extra waste is generated and it is not necessary to transport the remaining soil.

  As shown in FIG. 1, the load-introducing reinforced soil foundation 1 according to the present invention excavates only the surface layer portion of the sediment layer 21 of the natural ground to form a relatively shallow excavation portion 20A. The embankment layer 4 is constructed. Without laying the bottom plate in the excavation part 20A, while rolling the plurality of embankment layers as they are, the reinforcement material is laid and laminated between the embankment layers, and the upper plate 3 is installed at the uppermost stage. Finally, the anchor member 6 is driven.

  The anchor member 6 is an anchor member that reaches the support ground 22 through the upper board 3, the embankment layer 4, the reinforcing material 5, and the deposition layer 21, and is also an earth anchor that is generally employed for ground reinforcement. In addition, a screw-type earth anchor having a spiral protrusion at the lower portion may be used, and it may be selected and adopted according to the soil quality of the natural ground.

  The support ground 22 is a ground having a strength that can support the load-introducing reinforced soil foundation 1, and may be a foundation rock or a ground having an N value of 30 or more by a standard penetration test. Both can sufficiently serve as the supporting ground 22.

  As the anchor member 6, it is possible to adopt a bolt / nut type anchor member. However, by adopting an anchor member generally employed in civil engineering work such as ground reinforcement, as a result of ordinary civil engineering work. A load-introducing reinforced soil foundation can be created, which is preferable. Further, the number of the anchor members 6 is not particularly limited as long as the number of anchor members 6 is sufficient to exert a tightening force necessary for forming the foundation 1.

  After the anchor member 6 is driven deep into the ground of the deposition layer 21, the nut member 7 is screwed onto the screw portion formed at the upper end portion of the anchor member 6 and tightened to fasten the anchor member 6. The anchor member 6 driven deep in the ground of the layer 21 does not move, but each embankment layer is tightened and prestress is applied, and the prestress is also applied to the deposited layer 21 in which the anchor member 6 is driven. Added state. Further, this pre-stress is applied even to the deposited layer 21 in which the anchor member 6 is driven, as shown by a broken line in the figure. It became clear that it was expanding.

  This is because the ground of natural ground is a sedimentary layer 21 in which sandy soil and cohesive soil are mixed or in an alternating layer state, and even if a compressive force is applied, it is compressed as it is without lateral flow. This is because it is in a prestressed state.

  The sandy sediments surrounding the foundation are originally restrained from the surrounding ground, and when loaded by anchor force, the soil does not flow laterally to the surroundings, and the lower ground of the frame is due to the preload effect, Since strength increase and settlement are promoted, it is stable as a foundation even if a reinforcing material is not arranged. The stability of the foundation means that the foundation is stable with respect to sliding, falling, and supporting force.

  For this reason, in natural ground with a sedimentary layer in which sandy soil and cohesive soil are mixed, the surface layer is leveled and excavated to construct a reinforced soil foundation and anchor members are driven deep into the sedimentary layer. Thus, it is possible to form a reinforced soil pseudo-enclosure that is expanded to a size obtained by extending the constructed reinforced soil foundation to the basement. That is, the load-introducing reinforced soil foundation according to the present invention constitutes a foundation ground that has been expanded beyond the size of a reinforced earth body composed of a multi-layered embankment layer and an upper board.

  At this time, as shown by a solid line in the figure, as the anchor member 6, the anchor member 6 </ b> A penetrating through the deposition layer 21 and driven into the support ground 22 is also used when the deposition layer 21 is deep and strong. May be anchor members 6B (indicated by imaginary lines) that are driven deeply into the deposited layer 21. In the case where the deposited layer 21 is thick and deep ground, the anchor member 6B may be installed only in the deposited layer 21. When the deposited layer 21 is relatively thin and the supporting ground 22 is close to the ground surface. By driving to the support ground 22, the installation strength of the anchor member 6A can be further increased. Even in a state in which the anchor member 6A is driven to the support ground 22, an enlarged reinforced soil foundation ground (indicated by a broken line in the figure) in which a prestress is applied to the deposited layer 21 between the load-introducing reinforcement soil foundation 1 and the support ground 22 is provided. Range shown) is formed.

  That is, the load-introducing reinforced soil foundation to which prestress is applied is in a prestressed state even when the size of the reinforced soil body is a pseudo skeleton 1a and the load is Ha, as shown in FIG. It becomes a state equivalent to disposing the soil equivalent load height 1b of the load Hb on the upper part of the pseudo housing 1a, and an apparent ground improvement zone 1c is formed in which a preloading load corresponding to Ha + Hb is added in the deposited layer. Will be. Therefore, as the load-introducing reinforced soil foundation, a foundation expanded to the reinforced soil pseudo-enclosure 1a + 1b + 1c having a load corresponding to Ha + Hb + Hc shown in the figure is formed, and passive earth pressure is generated in the soil around the foundation, The apparent load is several times the weight of the reinforced earthen body, and exhibits a slip suppression force that is greater than the weight of the pseudo-body 1a.

  Therefore, as shown in FIG. 3A, it is preferable to apply the load-introducing reinforced soil foundation 1 according to the present invention to a banking method that suppresses slope slip. In particular, the load-introducing reinforced soil foundation 1A installed at the bottom of the long slope is a relatively small load-introducing reinforced soil foundation 1A to be constructed in order to exhibit a slip suppression force that exceeds its own weight as described above. Even if it exists, it will be constructing the big foundation which consists of a large reinforced earth pseudo-frame, and it is suitable as a reinforcement retaining wall with respect to the landslide 23 while exhibiting the effect of a prestress to the maximum and preventing the long slide S1.

  Further, another load introduction reinforcing soil foundation 1B may be installed on the upper part of the load introduction reinforcing soil foundation 1A to be installed on the above-mentioned butt, so as to sequentially separate the slip and prevent the fragmentation slip S2. . In this divided slip S2, the slip direction is horizontal to the construction body, and the frame resistance is increased, which has a great effect on the slip prevention force. That is, the load-introducing reinforced soil foundation 1B has a function of reinforcing the sedimentary layer on the inclined surface portion and preventing the debris flow 24.

  Furthermore, after leveling and digging the surface layer at an arbitrary position on the slope, a small load-introducing reinforced soil foundation 1C that does not protrude to the ground surface is installed to reinforce the ground of the slope portion. A foundation is also effective.

  Furthermore, as shown in FIG. 3 (b), after the surface layer portion is leveled and excavated, the upper board 3 is disposed, and the anchor member 6 is driven to the support ground 22 and tightened, and then the deposited layer 21 is obtained. A compressive force is applied to form a reinforced soil pseudo-frame in the range indicated by the broken line in the figure, and even this simple configuration can be a construction method for reinforcing the ground of natural ground.

  As described above, when vertical pressure is applied to the sedimentary layer of natural ground, passive earth pressure is applied to the surrounding soil inside the sedimentary layer, increasing the ground strength. This is because the ground of natural ground is composed of sedimentary layers in which sandy soil and cohesive soil are mixed, and it is difficult for side flow to occur even when prestressed. In addition, the area where the ground strength increases is not limited to the area of the upper board to be pressed, but expands to a lower part in a trapezoidal cross section, which is optimal for ground reinforcement of natural ground. .

  In addition, if a conventional natural ground reinforcement method such as a reinforcement method by inserting reinforcing bars is applied before the prestress is applied to form a combination method, the ground reinforcement effect can be further increased.

  In the ground reinforcement method according to the present invention, since the surface layer portion of the ground is only leveled and excavated, the amount of soil to be excavated can be small. Therefore, the construction scale can be reduced. Furthermore, since the anchor member is driven and tightened after the load-introducing reinforced soil foundation is constructed without using the bottom plate, after the bottom plate is installed and the anchor member is installed, as in the conventional reinforced soil foundation method, It is not necessary to repeat the rolling and laying of the reinforcing material, the process is simplified, the construction period can be shortened, and an inexpensive ground reinforcement method is provided.

  FIG. 4 shows an example in which the load-introducing reinforced soil foundation according to the present invention is arranged in a river channel, where (a) shows a transmission type dam and (b) shows a diversion bank.

  The load-introducing reinforced soil foundation 1D shown in FIG. 4 (a) is a reinforced soil foundation constructed by excavating the riverbed a little, and has a configuration in which a plurality of staggered flows are arranged in order from the upstream to the downstream of the basin. Passes through without depositing, and the flow energy of water is absorbed and attenuated when colliding with a plurality of the foundations. Therefore, the arrows in the figure indicate that the original flow energy 30 is attenuated to the flow energy 31 when passing through the transmission type dam.

  Further, each of the load-introducing reinforcing earth foundations 1D has a small-scale structure configuration, and may be a civil engineering work that is much smaller than an impervious type dam constructed over the entire river width. Moreover, since the amount of soil to be excavated is small, there is no adverse effect on the environment.

  A load-introducing reinforcing earth foundation 1E shown in FIG. 4B is a diversion bank that causes a gentle flow by meandering the flow of the river, and is an example in which a plurality of staggered foundations are arranged alternately on both sides of the river. In this arrangement example, the water flow sequentially collides with each foundation, and the flow is deflected to meander. Therefore, the arrow in the figure indicates that the original flow energy 32 is attenuated to the flow energy 33 when passing through the diversion bank.

  Further, when the anchor member 6 is tightened during the ground reinforcement method for natural ground and the construction of a dam in a river channel, as shown in FIG. 6, a fastening member 8 that applies tension and prevents loosening is disposed. If it is set as the structure provided, predetermined | prescribed clamping force can be added and also loosening of clamping force can be prevented.

  The anchor member 6 applies a preload to the embankment in the vertical direction to advance plastic strain, and suppresses the residual settlement during service. Next, by unloading a part of the preload to bring it into a prestressed state, the restraining pressure in the embankment can be maintained at a high value, and the shear resistance and rigidity during operation can be dramatically increased.

  Therefore, by adopting a configuration that maintains a prestressed state, even if a repeated load such as an earthquake is applied, by suppressing bending deformation and maintaining the vertical restraining force of the embankment, an integrated reinforced soil pseudo-enclosure Can be maintained.

  In the fastening member 8 shown in FIG. 6A, a shear rubber spring material E is disposed on an installation base 80 having a circular opening 80A through which the anchor member 6 can be inserted at the center so as to close the opening 80A. This is the configuration. That is, the anchor member 6 protruding from the upper board 3 is fixed with the set screw 80a so as to cover the groove-shaped base-like installation base 80 opened on the lower side, and the anchor member 6 is mounted on the opening 80A. The shear rubber spring material E is disposed so as to be inserted.

  The shear rubber spring material E has a configuration in which an annular rubber elastic body layer 83 is sandwiched between a hollow cylindrical inner metal member 81 and a casing metal member 82. It is firmly bonded by the method. For this purpose, the inner metal member 81 and the casing metal member 82 can be displaced via the rubber-like elastic layer 83 in the cylindrical axis direction.

  The shear rubber spring material E is installed in a circular opening 80 </ b> A provided at the center of the upper end of the installation table 80. At this time, it is preferable that the projecting portion 80B is provided on the peripheral edge of the opening 80A and the lower end portion of the casing fitting 82 is mounted on the projecting portion 80B so that the installation position is restricted. After installing the shear rubber spring material E, when the first nut member 7 is screwed into the screw portion 6a at the upper end portion of the anchor member 6 and the upper end of the inner fitting 81 is pushed down through the washer 9, The rubber-like elastic body layer 83 is elastically deformed while the metal fitting 81 is pressed, and is pressed down to the position 81A as shown by the solid line in the figure.

  A tension force corresponding to the elastic deformation amount of the rubber-like elastic body layer 83 is applied to the anchor member 6, and further, while being elastically deformed following the settlement of the embankment or foundation ground or the extension of the anchor member, a predetermined amount is obtained. It is the structure which gives the tension power of. That is, the shear rubber spring material E constitutes a pressurizing means that applies tension to the anchor member 6 by the installation base 80 and the first nut member 7.

  As an example of the degree of tension, when the thickness T of the rubber-like elastic body layer 83 is 40 mm and the length H is 450 mm, the inner metal member 81 is pushed down by 60 mm, and the extension of the rubber-like elastic body is 60 mm. In this case, a tension force of about 1000 kN (about 100 tons) is obtained when the inner metal member 81 is pressed 100 mm and the elongation of the rubber-like elastic body is 100 mm.

  Therefore, if the extension of the rubber-like elastic body is configured to apply the tension of the anchor member 6 in the range of 60 to 100 mm, a state in which a tension of 600 kN or more is always applied to one anchor member is maintained. be able to.

  At this time, in addition to the pressurizing means, if the fastening member 8 is configured to include the loosening prevention means F including the second nut member 84, the spring spring member 85, and the support 86, the tightening force It is possible to further prevent the slackening.

  The second nut member 84 is configured to be fixed to the upper board 3 by a plurality of set screws 86a, and a support body 86 having an annular shape and a concave portion on the inner side with a slight gap in the radial direction. The spring spring material 85 can be accommodated.

  One end of the spring spring member 85 is fixed to the second nut member 84 and the other end is fixed to the support 86, and the urging force of the spring member 85 is tightened in the second nut member 84. It is set to head.

  Therefore, after the shear rubber spring material E is fastened and fixed, the second nut member 84 attached to the second screw portion 6b of the anchor member 6 is rotated and fixed to the upper board 3. Thereafter, when the support body 86 is fixed to the upper board 3 with the set screw 86a in a state in which the mainspring spring 85 is tightened, the urging force of the mainspring spring 85 acts in the direction in which the second nut member 84 is tightened. It can be configured.

  If it is set as said structure, since it becomes the structure currently urged | biased in the direction in which the 2nd nut member 84 which fastens the top board 3 and the anchor member 6 which comprise a reinforced earth foundation is fastened, The applied pressure of the shear rubber spring material E can be reliably and stably applied to the anchor member 6 and the upper board 3 for a longer period of time. Further, by disposing the cover member 87 that covers the upper surface of the spring spring member 85, it is possible to prevent foreign matters and the like from entering the spring member 85 portion.

  As shown in FIG. 6B, the shear rubber spring material E has a shape (indicated by an imaginary line in the figure) in which the inner metal member 81 and the casing metal member 82 are shifted up and down to form a stepped shape. When the upper end of the inner metal member 81 is pushed down by the first nut member 7 through the washer 9, the upper end surface of the inner metal member 81 is the upper end surface of the casing metal member 82. It can be set as the structure which provides predetermined | prescribed tension | tensile_strength by pressing until it becomes substantially horizontal (it shows as the continuous line in a figure).

  In the above configuration, when the tension force is loosened, the horizontal state between the upper end surface of the inner metal member 81 and the upper end surface of the casing metal member 82 is discarded, and the upper end surface of the inner metal member 81 shifts in a competitive direction. When the first nut member 7 is immediately retightened, the tension can be readjusted.

  In any case, the fastening member for applying a predetermined tension force can be configured using the shear rubber spring material E having a single structure, so that not only the structure is simple but also the operation becomes easy.

  The above-described shear rubber spring material E has a configuration in which the mainspring spring material 85 follows the rotation of the second nut member 84 by the amount of subsidence (volume reduction) due to the plastic deformation of the foundation to maintain the prestressed state. Further, when an external force is applied to the densely packed embankment body, the embankment body tends to undergo volume expansion due to shear deformation, but the second nut member 84 is always rotated in the tension direction of the anchor member 6. Therefore, the volume expansion of the reinforced soil foundation is prevented without reversing.

  In other words, it has a function to keep the height of the embankment constant, suppresses volume expansion of the reinforced soil foundation, and constantly urges the second nut member 84 in the tightening direction. It is also possible to suppress repeated bending deformation due to impact such as.

  Further, as shown in FIG. 7, second loosening prevention means FA including a worm gear constituted by a worm 88 and a worm wheel formed on the outer edge of the second nut member 84A is arranged in place of the mainspring spring member 85. It is good also as a structure to install.

  As a worm gear configuration in which a worm 88 rotatably mounted on a mounting base 80D fixed to the upper board 3 via a bush 88A meshes with a worm wheel formed on the outer edge of the second nut member 84A, By rotating, the second nut member 84A is made rotatable.

  A disk 89 having a handle 89 </ b> A is provided at one shaft end of the worm 88. By turning the handle 89A attached to the outer edge of the disk 89, the worm 88 can be rotated lightly. Further, the second spring member 85A is disposed between the disk 89 and the installation base 80D so as to urge the rotation direction of the worm 88 in one direction, so that the second nut member 84A is tightened. If the structure is always urged, the reverse rotation of the second nut member 84A can be prevented in the same manner as described above, the volume change of the reinforced soil foundation can be followed, and the strength and rigidity of the housing can be maintained.

  Further, a clutch member having a ratchet function may be attached to the second spring spring member 85A so as to further suppress loosening.

  However, in the example constituted only by the second spring spring material 85A, the degree of change can be visually confirmed by the position of the handle 89A that rotates following the volume change of the reinforced soil foundation. It is.

  Furthermore, even if the corrugated plate 8A shown in FIG. 8 is placed on the upper board 3 as the fastening member 8 and the first nut member 7 is fastened, a strong tension can be obtained, which is preferable. is there. Even with such a simple configuration, not only a predetermined tension force can be applied, but also the tightening force can be prevented from loosening.

  The corrugated plate 8A is a corrugated plate made of spring steel and has a configuration in which an elastic reaction force generated when the corrugated plate steel is tightened is used as a tightening force of the reinforcing soil. For this purpose, the corrugated plate 8A having a clear spring property is tightened by the nut member 7. Therefore, the degree of tightening of the nut member 7 can be determined from the amount of deformation of the corrugated plate 8A. And a stable tightening force can be maintained over a long period of time. Furthermore, even when tightening is loosened due to deformation or loss of the reinforced soil, the amount of deformation changes within the elastic range of the corrugated plate 8A while maintaining a predetermined tightening force. It is.

  Of course, a large wave washer can be used instead of the corrugated plate 8A, but in order to obtain a large clamping force for pressing the embankment layer, a corrugated plate of a spring steel plate that can be processed into a large area is preferable.

  Since the anchor member 6 is configured to be tightened via a corrugated sheet 8A, which is a simple sheet metal part, the anchor member 6 can be easily prevented from loosening without using a complicated locking device. It has the effect.

  As described above, when only the surface layer portion of the natural ground is leveled and excavated to construct the load-introducing reinforced soil foundation 1, the sediment layer which is the lower ground of the foundation 1 is also in the load-introducing reinforced soil foundation state. Therefore, it is possible to work efficiently only by civil engineering. In addition, the conventional ground improvement method using concrete or cement-based solidified material requires the work of digging up the soft ground, adding the solidified material and compacting it, and the period of time for hardening becomes long, resulting in large-scale work. Although heavy construction equipment is required and construction is long and difficult, in this embodiment, the entire process of constructing the reinforced soil foundation can be constructed in a short time as a series of continuous processes. And since only the surface layer part of the natural ground mountain is excavated and the reinforced soil construction work is performed, it can be said that it is a natural-friendly construction method and is also suitable for environmental conservation.

  In other words, the ground reinforcement method using the load-introducing reinforced soil foundation according to the present invention is also a ground reinforcement method for constructing a large load-introducing reinforced soil foundation by small-scale civil engineering work, even in a narrow terrain in a mountainous area. It is a construction method that allows construction to be performed relatively easily, shortens the construction process, and keeps construction costs low.

  Next, a second embodiment will be described with reference to FIGS.

  FIG. 9 shows an example in which the foundation of the structure is constructed on the slope of the natural ground using the load-introducing reinforced soil foundation according to the present invention, and FIG. Is shown.

  The load-introducing reinforced soil foundation 1F shown in FIG. 9 excavates the sediment layer 21 on the slope surface up to the supporting ground 25, cuts the upper surface of the supporting ground 25 to create a flat portion 25a, and excavates the field. After the earth or high-quality earth is backfilled and rolled to form the replacement layer 20C, the reinforcing material 5 and the embankment 4 are laminated thereon to construct the reinforced earth foundation, and after the upper board 3 is installed, the anchor member 6 Until the support ground 25 is reached, the tip is fixed by mortar injection or the like, and is tightened and tightened. Further, a pedestal 12 can be installed on the upper board 3, and a bridge girder 13 or the like can be installed on the pedestal 12.

  The load-introducing reinforced soil foundation 1F is made of soil, so it is light in weight, and can be constructed near the slope rather than the mountain side of the slope. When it is used as an abutment, the bridge girder span can be shortened. it can.

  Since the load introduction reinforcing soil foundation 1F is configured to construct a foundation structure on a support ground in a horizontal state, a special slope design is not required and the construction is easy. Moreover, the conventional diagonal auxiliary anchor shown in FIG. 10 is unnecessary, and the complex design calculation of anchor tension force is also unnecessary.

  In the conventional basic structure shown in FIG. 10, the anchor member 6 is installed in the vertical direction of the support ground 25, and the auxiliary anchor 6C that is driven obliquely in a direction substantially orthogonal to the inclined support ground 25 is provided, so that the load-introducing reinforcement soil is provided. It is necessary to urge the foundation 11 to the support ground 25 to prevent lateral movement and settlement of the foundation, and it is difficult to set the tension force of the anchor member 6 and the auxiliary anchor 6C. It is also difficult.

  When the anchor member 6 and the auxiliary anchor 6C are driven into the inclined surface 25b and the respective tension forces are applied, if there is an imbalance in the tension force, the inclined surface as shown by an imaginary line in the figure. A slip occurs along the line 25b to form a base 11A that has moved sideways, which leads to a decrease in ground supporting force.

  Therefore, in the construction stage, if the required support force cannot be obtained due to lateral movement or settlement due to the tension imbalance between the vertical anchor member 6 and the oblique auxiliary anchor 6C, the construction is performed. It may be canceled and returned.

  The load-introducing reinforced soil foundation 1F according to the present invention shown in FIG. 9 is easy in design calculation and can confirm the ground strength of the excavated ground during construction. The height can be changed, and the design can be easily changed. Moreover, since it is normal embankment construction, it can be operated by a normal civil engineer by performing rolling pressure management, and does not require a special technician.

  Also in the present embodiment, the simulated skeleton by the reinforced soil may be only a shallow portion of the surface layer portion. A foundation body that is greatly expanded downward in a trapezoidal cross section is configured at the lower part of the reinforced soil simulated housing.

  Furthermore, if the locally generated soil that is excavated residual soil is poor, it can be reused by dewatering and reforming by improving lime mixing, etc., so it is not necessary to discard the excavated soil and transport it. From this point, it is a construction method suitable for narrow terrain such as a mountainous area, and it is environmentally friendly and can achieve cost reduction.

  Further, since the anchor member is driven through the foundation composed of the multi-layered embankment layer and deep into the ground of the sedimentary layer, not only the foundation but also the sedimentary layer below the foundation is integrated. It is possible to obtain the same effect as that obtained by forming a load-introducing reinforced soil pseudo-frame and constructing a large foundation ground. Furthermore, when prestressing is applied to the foundation frame, a passive earth pressure is generated in the surrounding soil and the ground strength is further improved, which is effective as a ground reinforcement method.

It is sectional drawing which shows the 1st Example of the load introduction reinforcement | strengthening soil foundation which concerns on this invention. It is a schematic explanatory drawing which shows the effectiveness of the load introduction reinforcement | strengthening soil foundation which concerns on this invention. It is a schematic explanatory drawing which shows the Example which prevents a slope slip, (a) shows the ground reinforcement construction method by a load introduction reinforcement earth foundation, (b) shows the ground reinforcement construction method by an upper board and an anchor member. The example which has arrange | positioned the load introduction reinforcement | strengthening soil foundation which concerns on this invention in the river flow path is shown, (a) shows a transmission type dam, (b) shows a diversion bank. It is sectional drawing which shows the reinforced soil foundation by the conventional construction method. It is sectional drawing which shows the upper end part structure of an anchor member provided with a fastening member and a loosening prevention means. It is a perspective view which shows the 2nd loosening prevention means provided with a worm gear. It is a schematic explanatory drawing which shows the upper end part structure of an anchor member provided with a corrugated sheet as a fastening member. It is sectional drawing which shows the 2nd Example which comprised the foundation of the structure in the slope part of the natural ground using the load introduction reinforcement | strengthening earth foundation which concerns on this invention. It is sectional drawing which shows the basic composition of the structure by the conventional load introduction reinforcement earth foundation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Load introduction reinforcement earth foundation 1a (Load introduction) Reinforcement earth pseudo frame 3 Upper board 4 Embankment layer 5 Reinforcement material 6 Anchor member 8 Fastening member 10 Load introduction reinforcement earth foundation (conventional)
20A excavation part 20B (conventional deep) excavation part 21 sedimentary layer 22 support ground 81 inner metal fitting 82 casing metal fitting 83 rubber-like elastic body layer 84 second nut member 84A second nut member (equipped with worm wheel)
88 Worm E Shear rubber spring material (Pressurizing means)
F Loosening prevention means FA Second loosening prevention means

Claims (7)

  Excavating by leveling the surface layer part, disposing a highly rigid upper board thereon, providing an anchor member that penetrates the upper board and the deposited layer at the lower part of the upper board and reaches the support ground, The first nut member is screwed into the threaded portion formed at the upper end of the anchor member, and the anchor member is tightened and tensioned to apply a compressive force to the deposited layer to increase the strength of the deposited layer. A ground reinforcement construction method characterized by having a structure to reinforce.   The surface layer part is leveled and excavated, and a multi-layered embankment layer is formed thereon, a flat or substantially flat mesh-like or lattice-like reinforcing material interposed between each embankment layer and having a large friction coefficient and tensile strength, and an uppermost layer. After a highly rigid upper board is arranged on the embankment layer and a reinforced earth body is formed, the upper board, the reinforcing material, the embankment layer, and the deposited layer below the embankment layer are penetrated to reach the support ground. An anchor member is provided, a first nut member is screwed into a screw portion formed on the upper end portion of the anchor member, and the anchor member is tightened and tensioned, so that not only the embankment layer but also the deposited layer A ground reinforcement construction method characterized by forming a reinforced soil pseudo skeleton by applying a compressive force and forming a load-introducing reinforced soil foundation larger than the reinforced soil body to reinforce the ground.   Drilling from the surface layer part to the support ground, stepping the support ground to create a plane part, and laminating back-filled soil or high-quality soil on the plane part while rolling, and multilayering on it Reinforced by embedding the embankment layer, a flat or substantially flat net-like or lattice-like reinforcing material that is interposed between each embankment layer, and has a high friction coefficient and tensile strength, and a highly rigid upper board on the uppermost embankment layer After forming the earthen body, an anchor member that penetrates the upper layer, the reinforcing material, the embankment layer, and the rolling compaction layered portion at the lower part of the embankment layer to reach the support ground is provided, and is formed at the upper end of the anchor member The first nut member is screwed to the threaded portion, and the anchor member is tightened and tensioned, so that not only the embankment layer, but also the rolling compaction portion is subjected to a compressive force, and the reinforced soil pseudo frame is formed. Introducing a load that is larger than the reinforced earth Ground reinforcement construction method, characterized in that to form the strongly soil foundation and the structure for reinforcing the ground.   When the first nut member is screwed into the screw portion formed at the upper end portion of the anchor member and the anchor member is tightened and tensioned, the rubber-like elasticity is provided between the hollow cylindrical inner metal fitting and the casing metal fitting. The ground reinforcement method according to any one of claims 1 to 3, wherein a tension is applied via a fastening member using a shear rubber spring material having a structure in which a body layer is sandwiched as pressure means.   In addition to the pressurizing means, the fastening member further includes a loosening prevention means including a second nut member and a spring spring material that biases the second nut member in the fastening direction. The ground reinforcement method according to claim 4, wherein   A configuration in which a worm wheel is formed on the outer edge of the second nut member, a worm that engages with the worm wheel is disposed, and the second nut member is urged to rotate in the tightening direction. The ground reinforcement construction method according to claim 5, wherein: A ground reinforcement construction method characterized in that, instead of a fastening member using the shear rubber spring material according to claim 4 as a pressurizing means, the tension is made via a fastening member made of a corrugated plate made of spring steel. .

Images