JP2007231629A - Construction method of stabilizing ground - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a construction method of stabilizing a fill-up ground capable of stopping the sliding of the entire part of the fill-up ground produced along a sloped original ground surface. <P>SOLUTION: A plurality of boring holes 5 are formed, in rows, in the boundary portion A between the sloped original ground 1 and the fill-up ground 2 constructed on the original ground 1 along near the boundary surface between the original ground 1 and the fill-up ground 2 in the direction of the slope of the original ground 1. A holed pipe such as a vinyl chloride tube or a steel tube is inserted into each of the boring holes 5 to form a drain hole 3. Improved ground parts 4 are formed between the drain holes 3. The improved ground parts 4 are formed by pouring a solidifying material into the boring holes 5 and solidifying the ground around the boring holes 5 over a specified range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a ground stabilization method, in particular, it is created by valley filling embankment that fills the original ground of the valley, and is applied to stabilization of the ground of the construction land used as residential land, factory construction land, or road, Landslide disasters during earthquakes and heavy rainfall can be prevented.

  In recent years, embankment embankment is generally performed to fill land on the valley ground to secure land such as residential land, factory construction site, or road. The embankment ground created by the valley filling embankment is different in nature from the ground and the embankment ground. It is predicted that

  For this reason, the shear strength of the boundary surface between the original ground and the embankment is small, and when an external force is applied due to an earthquake or the like, the entire embankment tends to landslide at the interface with the original ground.

  In particular, after heavy rain, a large amount of rainwater that has penetrated into the embankment is expected to flow from the upstream to the downstream as groundwater on the original soil surface, so that the embankment is saturated. This may cause osmotic pressure, increase in embankment weight, decrease in ground strength, etc., and may develop into a large-scale landslide disaster near the boundary surface.

  Conventionally, as a method for preventing such a landslide disaster, for example, a method shown in FIGS. 11A and 11B is generally known. In the method illustrated in FIG. 11A, a retaining wall 21 is constructed in a stepped shape in the upstream direction on the downstream side of the embankment 20, and an anchor or drain hole 21 is constructed from each retaining wall 21 into the embankment 20. In the method shown in FIG. 11 (b), a water collecting well 23 is provided in the embankment 20, and a horizontal boring hole 24 for collecting water is drilled from the water collecting well 23 into the embankment 20. It is a method to do.

Patent 2509005

  Although these methods could strengthen the ground of the embankment itself, it was insufficient to prevent the landslide disaster of the entire embankment that occurred near the boundary between the original ground and the embankment. In addition, there are known a consolidation method for improving a part of the ground by injecting a solidifying material into the embankment and a drainage method for drilling a drain hole.

  However, the consolidation method has the effect of storing groundwater due to impermeability, and workability on unstable slopes and work within a living area such as a house on a slope hinder the normal living environment. This is not preferable. Moreover, the same problem arises at the time of the operation | work for providing a drain hole.

  In addition, each method is insufficient as a ground countermeasure at the boundary between the original ground and the embankment, which is particularly problematic, and cannot prevent landslide of the entire embankment along the original ground surface. Met.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a ground stabilization method capable of preventing a landslide of the entire embankment in particular.

  The ground stabilization method according to claim 1 is characterized in that a plurality of drilling holes are provided along the vicinity of the boundary surface between the original ground and the embankment in the boundary between the original ground and the embankment built on the original ground. Then, a plurality of rows of holes are drilled in the direction of inclination of the original ground, and the boreholes are used as drainage holes.

  In particular, the present invention intends to prevent landslide disasters by stabilizing ground at the boundary surface by actively draining groundwater at the boundary between the original ground and the embankment.

  In this case, the boring hole can be drilled very efficiently along the ground surface of the original ground by using the induction type curved boring capable of guiding the traveling direction on the ground. Each drainage hole is easily formed by inserting a perforated pipe in which a number of drain holes are formed in the outer peripheral wall of a pipe such as a vinyl chloride pipe, a steel pipe, or a corrugated pipe in the borehole immediately after drilling. be able to.

  The drain holes may be formed continuously in the inclination direction of the original ground, or may be formed over a certain range only on the downstream side portion. Further, the drain hole may be formed by meandering in the inclined direction along the vicinity of the boundary surface.

  The ground stabilization method according to claim 2 is a ground stabilization method for a valley-filled land created by embankment in a valley, and the present invention relates to a residential land or factory construction created by a so-called valley-filled embankment. In the area where land and roads are constructed, the boundary between the original ground and the embankment is saturated with groundwater and is prone to landslides. By draining automatically, this part is prevented from becoming saturated, the ground is stabilized, and large-scale landslide disasters are prevented in advance.

  The ground stabilization method according to claim 3 is the ground stabilization method according to claim 1 or 2, wherein the boring hole is formed by induction bending boring.

  By using the induction type curved boring capable of guiding the traveling direction on the ground to the borehole, the borehole can be efficiently drilled along the ground surface of the original ground. This is because the number of bores and the bore length for the drainage area of the slope can be reduced, and the drainage effect can be ensured.

  The ground stabilization method according to claim 4 is the ground stabilization method according to any one of claims 1 to 3, wherein the drainage hole is formed in a certain range of a downstream side portion of the original ground. Is.

  The ground stabilization method according to claim 5 is the ground stabilization method according to any one of claims 1 to 4, wherein the slope of the original ground is along the boundary surface between the drainage hole and the ground and the embankment. The formation of the ground improvement part is used in combination in the direction.

  The ground stabilization method according to claim 6 is the ground stabilization method according to claim 5, wherein the ground improvement part injects the solidified material into the bored hole drilled by bending boring or straight boring in the upstream part of the slope. Alternatively, it is formed by a stirring and mixing method or a high pressure injection method. In the present invention, if a part of the upstream ground is solidified as a ground improvement part, only the ground sliding force of the area acts, so that the downstream consolidated area can be reduced, or the sliding This has the effect of increasing the safety factor against

  In addition to solidifying material injection method using curved boring, solidifying material injection method using vertical boring or oblique boring, or injecting method is not limited to the method of consolidating a part of the upstream ground. A stirring and mixing method or a high-pressure injection method may be used. In addition, if upstream workability is good, it is sufficient to solidify outside the living area, and if it is solidified upstream, even if it is not consolidated in line, there is no worry of storage, and the surface There is an effect that permeation of water downstream can be blocked by its water tightness.

  The ground stabilization method according to claim 7 is the ground stabilization method according to any one of claims 1 to 6, wherein a boundary surface between the drainage hole and the drainage hole is near the boundary surface between the original ground and the embankment. Thus, a ground improvement portion that is continuous in the inclination direction of the original ground is formed.

  The ground stabilization method according to claim 8 is characterized in that in the ground stabilization method for the embankment according to any one of claims 1 to 7, a retaining wall is constructed on the downstream side of the embankment. is there. In this case, the retaining wall can be constructed by a block structure, a masonry structure, a reinforced earth retaining wall, etc., in addition to the RC structure.

  The ground stabilization method according to claim 9 is characterized in that in the ground stabilization method according to any one of claims 1 to 7, an anchor is constructed on the embankment and the tip of the anchor is fixed on the original ground. To do. In this case, for example, a reinforcing bar anchor (nailing anchor) or the like can be used in addition to a normal ground anchor or an anchor using prestress.

  For example, a reinforcing bar anchor (nailing anchor) or the like can be used. According to this construction method, the strength of the embankment can be directly reinforced by forming a kind of synthetic reinforced earth block by placing many rod-shaped reinforcing materials, mainly reinforcing bars, steel pipes, shaped steel, etc. in the embankment. .

  In the present invention, a drainage hole is provided in the boundary portion between the ground and the embankment that is saturated with groundwater and is prone to landslide, and the groundwater is forcibly drained. To stabilize the ground and reliably prevent large-scale landslide disasters.

  In addition, the drainage hole is drilled at the boundary between the original ground and the embankment by using induction bending boring, so that the borehole is drilled from outside the living area on the slope, and the drainage hole is formed. By injecting the solidifying material into the borehole, construction can be performed without invading the living area, and drainage can be performed easily and effectively with a small number of bores and an extended bore.

  FIGS. 1A and 1B show a built-up residential land created by embankment on an inclined ground surface. A embankment ground 2 is created on the original ground 1. A plurality of drain holes 3 are formed in the boundary portion A between the embankment ground 2 and the original ground 1 along the inclination direction of the original ground 1.

  Particularly, the drain holes 3 are continuously formed in a plurality of rows in the inclination direction of the original ground 1 along the vicinity of the boundary surface between the original ground 1 and the embankment 2. Each drain hole 3 has a bore hole drilled from the downstream side of the original ground 1 to the upstream side along the vicinity of the boundary surface between the original ground 1 and the raised ground 2 on the embankment 2 side, and a PVC pipe is formed in the bore hole. It is formed by inserting a perforated pipe made of steel, steel pipe or corrugated pipe.

  2 (a) and 2 (b) show that a plurality of drain holes 3 are arranged in a plurality of rows in the inclination direction of the original ground 1 in a certain range of the downstream side portion of the boundary portion A between the original ground 1 and the embankment 2 An example of the formation is shown.

  3 (a) and 3 (b), in the boundary portion A between the original ground 1 and the embankment 2, the above-described plurality of drain holes 3 are formed in a plurality of rows in the inclination direction of the original ground 1. FIGS. 4A and 4B show an example in which a plurality of ground improvement portions 4 are formed alternately between the drain holes 3 and 3 in the inclination direction of the original ground 1 alternately with the drain holes 3. FIGS. 1 is an example in which a plurality of drain holes 3 and a plurality of ground improvement portions 4 are alternately formed in a plurality of rows in a certain range on the downstream side portion of the boundary portion A between 1 and the embankment 2. .

  5 (a) and 5 (b) show a plurality of drain holes 3 and ground improvement portions 4 on the downstream side and upstream side of the boundary portion A between the raw ground 1 and the embankment 2 respectively. It shows an example formed in a plurality of rows along the inclination direction.

  In any example, the ground improvement unit 4 drills a borehole from the downstream side to the upstream side in the boundary portion A of the embankment ground 2 with the original ground 1 and from the borehole to the ground around the borehole. It is formed by solidifying the ground around the boring hole over an integral range by injecting a solidifying material.

  Thus, by forming a plurality of drain holes 3 in the boundary portion A between the original ground 1 and the embankment 2 and forcibly draining the groundwater of the boundary A, the boundary between the original ground 1 and the embankment 2 The landslide of the embankment 2 in the part A can be prevented in advance. Moreover, by forming the ground improvement part 4 between each drain hole 3 and 3, the stabilization of the ground of the boundary part A can be improved and the landslide disaster especially at the time of heavy rain can also be prevented reliably.

In addition, the formation of drainage holes at the boundary between the original ground and the embankment continuously along the boundary surface between the original ground and the embankment in the inclination direction of the original ground is particularly effective during landslide disasters during heavy rain. This method is extremely effective as a preventive measure, and in general during and immediately after heavy rain, the embankment is in a saturated state and is prone to landslide destruction, but the embankment is saturated by forcibly draining groundwater. By avoiding this, large-scale landslide disasters can be prevented.
The drainage hole can be easily formed by inserting a perforated pipe provided with a number of drain holes in a pipe such as a PVC pipe, a steel pipe or a corrugated pipe. Further, the drain hole may be drilled in a state meandering in an S shape, for example, in the inclination direction of the ground.

  Next, the construction procedure of the ground stabilization method of the present invention will be described.

  First, as shown in FIGS. 6A and 6B, the boring hole 5 is drilled by boring on the embankment 2 side at the boundary portion A between the original ground 1 and the embankment 2. In this case, inductive bend boring that can be guided from the ground is used for boring, and the boring hole 5 is continuously formed in the downstream upstream direction of the original ground 1 along the boundary surface between the original ground 1 and the embankment 2. Drill holes.

  The guided bending boring includes a device for transmitting position information to the boring head, receives a signal transmitted from the transmitting device on the ground, and sets the drill head 6a based on the display on the boring work panel. It is used to operate or to operate the direction of boring with a gyro.

  Specifically, a boring rod 6 having a drill head 6a for embedding excavation and a taper blade 6b for changing the excavation direction as shown in FIGS. 6 (a) and 6 (b) is inserted into the casing 7. Then, the drill head 6a is rotated along the vicinity of the boundary surface into the embankment board 2 from the downstream side to the upstream side for boring. At that time, the direction of the boring can be appropriately changed by stopping the rotation of the taper blade 6b and changing the direction. When the boring hole 5 reaches the upstream side, only the casing 7 is left and the boring rod 6 is pulled out.

  Next, a perforated pipe (not shown) is continuously inserted into the boring hole 5 from the downstream side to the upstream side. In parallel with this, the casing 7 is pulled out. By the above method, the drainage hole 3 continuous in the inclination direction of the original ground 1 can be formed in the boundary portion A between the original ground 1 and the embankment 2.

  Next, the construction method of the ground improvement part 4 will be described. After drilling the bore hole 5 by the above-described method, the injection pipe 8 is inserted into the casing of the bore hole 5 as shown in FIG. While pulling out the casing (the casing is omitted in FIG. 7A). The injection tube 8 is composed of, for example, an outer tube 9 and an inner tube 10 inserted into the outer tube 9 as shown in the figure, and a distal support valve 9a made of a rubber sleeve or the like is provided at the tip of the outer tube 9. The discharge ports 9b are formed at predetermined intervals in the longitudinal direction and the circumferential direction of the outer tube 9, and the expansion packers 11 are attached to both sides of each discharge port 9b.

  The expansion packers 11 and 11 are expanded by a fluid (air or liquid) or a solidified liquid fed from the ground via the injection pipe 12a, and strongly press the hole wall of the boring hole 5 so that the outer tube 9 is bored into the boring hole. 5 and a sealed space 13 is formed between the boring hole 5 and the outer tube 9. The sealed space 13 in this case is formed by the hole wall of the boring hole 5, the outer tube 9, and the left and right expansion packers 11 and 11.

  On the other hand, expansion packers 14 and 14 are attached to the distal end portion of the inner tube 10 at predetermined intervals. The expansion packers 14 and 14 are expanded by the air or liquid sent from the ground via the injection pipe 12b in the same manner as the expansion packers 11 and 11, and press the inner wall of the outer tube 9 strongly, thereby causing the inner tube 10 to move to the outer tube. In addition to being fixed in the inner space 9, a sealed space 15 is formed between the outer tube 9 and the inner tube 10. In this case, the sealed space 15 is formed by the outer tube 9, the inner tube 10, and the left and right expansion packers 14 and 14.

  In such a configuration, in order to inject the solidified material into the embankment board 2 around the borehole 5 by the injection pipe 8, first, the outer pipe 9 of the injection pipe 8 is inserted into the borehole 5. Then, each expansion packer 11, 11 of the outer tube 9 is inflated by injecting air or liquid into the expansion packer 11, thereby fixing the outer tube 9 in the boring hole 5, and the outer tube 9 and the boring hole. A sealed space 13 is formed between the

  Next, the inner tube 10 is inserted into the outer tube 9, and each expansion packer 14, 14 is inflated by injecting air or liquid into the expansion packer 14. And a sealed space 15 is formed between the outer tube 9 and the inner tube 10.

  Next, the solidified material is fed into the sealed space 15 through the injection pipe 12c. The solidified material fed into the sealed space 15 is pushed into the sealed space 13 through the discharge port 9 b formed in the outer tube 9 and is injected into the embankment 2 around the sealed space 13.

  The outer tube 9 and the inner tube 10 can be freely moved again by removing the air or liquid injected into the expansion packers 11 and 14 and contracting the expansion packers 11 and 14, respectively.

  In this case, since the solidified material is injected into the ground around the sealed space 13, the ground improvement portion formed by the injection of the solidified material at one location is formed in a spherical shape, but the injection pipe 8 is connected upstream of the original ground 1. The ground improvement part 4 can be continuously formed from the upstream side of the original ground 1 in the downstream direction by repeatedly injecting the solidifying material while gradually pulling out from the side toward the downstream side.

  In the example of FIG. 7A, the solidified material is simultaneously injected into the plurality of sealed spaces 13 by one injection tube 12c. However, the plurality of injection tubes 12c are provided in the inner tube 10. It is also possible to insert the solidified material into each sealed space 13 through each injection tube 12c at the same time. Furthermore, it is possible to simultaneously inject the solidified material into the plurality of boring holes 5 using a plurality of injection tubes 8. By constructing in this way, the ground improvement part 3 can be formed very efficiently.

  In addition, when injecting solidified material such as mortar into the expansion packer 11 instead of injecting air or liquid, the outer pipe 9 is not recovered but is buried in the boundary portion A between the original ground 1 and the embankment 2 and the embankment 2 can be used as a reinforcing material.

  Although not shown in the above, the ground may be consolidated by pulling out the boring rod while injecting the injecting liquid from one or a plurality of flow paths in the boring rod of the curved boring, or directly injected from the outer tube The liquid may be injected, or the ground may be consolidated by pulling out the outer tube while injecting from the outer tube.

  FIG.7 (b) shows the other method of inject | pouring a solidified material into the embankment 2 around the boring hole 5, and the injection pipe 8 in this case is as the outer pipe | tube 9 demonstrated in FIG. After using the one without the expansion packer 11 and inserting the outer tube 9 into the boring hole 5, a low-strength gap filler 16 is filled between the boring hole 5 and the outer tube 9.

  Then, the solidified material is fed into the sealed space 15 through the injection pipe 12c. The solidified material fed into the sealed space 15 breaks through the low-strength gap filler 16 from the discharge port 9b of the outer tube 9 and is injected into the embankment 2 around the discharge port 9b.

  Also in this method, by repeatedly injecting the solidified material while gradually pulling out the injection pipe 8 from the upstream side of the original ground 1 to the downstream side, the ground improvement unit 4 can move from the upstream side of the original ground 1 toward the downstream side. It can be formed continuously.

  Alternatively, the gap filling material 16 may be filled in the boring hole 5 first, and then the outer tube 9 may be inserted into the boring hole 5. For example, a low-strength cement bentonite liquid can be used for the gap filler 16.

  Similarly to the case shown in FIG. 7A, the solidified material may be simultaneously injected into the plurality of sealed spaces 15 by one injection tube 12 c, or the plurality of injection tubes 12 c are provided in the inner tube 10. It is also possible to insert the solidified material into each sealed space 15 through each injection tube 12c at the same time. Further, a three-dimensional multi-point injection method can be used by using a plurality of injection pipes 8 and simultaneously injecting a solidified material into the plurality of boring holes 5.

  The three-dimensional multi-point injection method is a patented invention owned by the applicant (Japanese Patent No. 3724644). Briefly speaking, a plurality of injection pipes having discharge ports are formed into a plurality of injection pipes in the ground. It is a ground injection method that is buried at the point, and multiple ground improvement materials are simultaneously injected from the discharge port of each injection pipe through these injection pipes, each operating with an independent drive source, and with a centralized control device Using a multi-injection injection device having a large number of unit pumps to be controlled, the large number of unit pumps are connected to a plurality of injection pipes through a conduit. It is characterized by the fact that multiple injections are made through injection points in the ground.

  The present construction method also includes a storage tank for storing the ground improvement material, a multi-continuous injection apparatus connected to the storage tank, and a plurality of injection pipes having discharge ports. It is equipped with a number of unit pumps that are operated by independent drive sources and controlled by a centralized management device. The injection pipe is embedded in a plurality of injection points on the ground, and each is connected to each unit pump through a conduit. Further, the multiple unit pumps are independent and each include a rotational speed transmission controlled by a centralized control device, and the conduit includes a flow pressure detector.

  Then, a flow rate and / or pressure data signal from the flow rate pressure detector is transmitted to a central control device, and the ground improvement material in the storage tank is operated at any injection speed, injection pressure and injection amount by the operation of each unit pump. Thus, it can be pumped to each injection tube, and multiple points can be simultaneously injected into the ground from a plurality of discharge ports.

Next, the examination result of the ground stabilization method by solidification material injection | pouring is demonstrated.
The scale of the valley filling embankment to be examined was assumed as follows.
Embankment height 5.0 m
Embankment length 200.0 m
Embankment width 50.0 m
Inclination angle 10.0 degrees Unit volume weight of embankment γt = 17KN / m ³
Model ground Fig. 8 (a), (b)

  8 (a) and 8 (b), the embankment portion α tries to slide down along the vicinity of the boundary surface with the original ground β due to an external force acting due to an earthquake or the like. This is referred to as a force (hereinafter referred to as “sliding shear force”) W · sin θ that causes the slip to act on the sliding surface. On the other hand, a force (hereinafter referred to as “shear resistance force”) τ · L that acts to prevent this acts on the sliding surface. It is assumed that the sliding shear force W · sin θ and the shear resistance force τ · L are in a balanced state (limit state). That is, the ground strengthening method of the present invention was examined on the assumption that the safety factor Fs = 1.0.

In FIG. 8A, assuming that the sliding shear force W · sin θ and the shear resistance force τ · L are balanced,
Fs = τ · L / W · sinθ = 1.0 (Fs safety factor) ...... Formula 1
The shear resistance τ of the embankment lower boundary surface is obtained from Equation 1.

τ · L / W · sin θ = 1.0
τ · L = τ · 203KN / m
= 203 · τKN / m
W · sin θ = 200.0 m × 5.0 m × 17 KN / m ³ × sin 10 °
= 17000 x 0.17365
= 17000 x 0.174
= 2.958 KN / m
From Fs = 1.0 τ · L / W · sin θ = 203 · τ / 2.958
= 1.0
Therefore, shear resistance τ = 2.958 / 203
= 14.6KN / m ²
It becomes.

  As mentioned above, the current state where sliding shear force and shear resistance force are balanced with safety factor Fs = 1.0 is strengthened by chemical solution (solidification material) injection to increase the safety factor and stabilize the ground. And

  The chemical solution injection uses induction bending boring and adopts the three-dimensional multi-point injection method by the injection method of Fig. 8 (b), and the solution type permanent grout (active silica colloid "Perma Lock" reinforced soil engineering ( Registered trademark), or suspension-type permanent grout (registered trademark of ultrafine composite silica “hybrid silica” reinforced soil engineering Co., Ltd.) can also be used.

In the following examination, a permanent grout [a high-strength active silica colloid “Permalock High”, which can obtain a permanent improvement effect, was used for the injection material in consideration of the purpose of improvement (see Table 1). Table 2 shows the shear resistance τ ₁ of the improved ground by the three-dimensional multi-point injection method.

  In the case of ground improvement by a three-dimensional multi-point injection method using curved boring, the ground was strengthened for a total of 100 m, 50 m downstream and 50 m upstream, considering the accuracy and performance of curved boring. In addition, from the performance of the three-dimensional multipoint injection method, the improved body from one nozzle was examined as a spherical improved body having a diameter of 2.0 m and the improvement range was examined.

Consider a case where the safety factor Fs is improved to 1.5.
Calculate the improved area ratio μ.
From the equation Fs = τ · L / W · sin θ = 1.5 [μ × τ ₁ + (1−μ) × τ] × 203 / 2.951 = 1.5
μ = 2.958 × 1.5−14.6 × 203 / 203τ ₁ −2.964
= 1.473 / 203τ ₁ -2.964 Equation 3
When μ is calculated by substituting τ ₁ of the improved ground into Formula 2, the result is as shown in Table 3, resulting in Fs = 1.75 to 1.8.

  From the above, the improved area ratio of ground reinforcement by the chemical solution injection method (three-dimensional multi-point injection method) was set as shown in Table 4. And the improvement range in the model ground was examined from the examination results, and it became as follows (refer to FIGS. 9A and 9B for the improvement range).

  Table 5 shows the improvement rate, the improvement area, and the number of injection holes when the safety factor Fs is 1.5.

Model ground area S = 50.0 × 203.0 = 10.150.0 m ²
Necessary improvement area S ₁ = S × μ
The number of holes in the injection hole (improved part) was calculated with a length of 50.0 m per hole and an improved width of 2.0 m according to the characteristics of this method.
Improved area per hole Sg = 2.0 × 50.0 = 100.0 m ²

  Next, a description will be given of a result of examination in which the ground stabilization method by injecting the solidifying material described above is used in combination with the ground stabilization method by drilling a drain hole of the present invention.

Here, assuming that the shear resistance τ = 14.6KN / m ² of the embankment lower boundary surface is improved by 70% due to the construction effect of the drainage hole, the construction result area of the drainage hole is 3 m wide × 50 m long (+ α). / 1 drainage hole × 8 = 1200 m ² , multiplying this by 14.6 × 0.7 increases the shear resistance by 12264 KN, and increases by 245 KN per unit width.

  Therefore, Fs = 245 KN / 2958 KN / m = 0.08. The intervals between the drain holes were set as shown in FIGS. 10A and 10B in consideration of the combined effect with the solidifying material injection hole (ground improvement part).

Next, consider the time of an earthquake.
Fs = τ · L / W · sinθ + Kh · W · cosθ
Kh is the design horizontal seismic intensity The model ground has a relatively shallow embankment thickness of 5.0 m, so the design horizontal seismic intensity Kh was set to 0.16.
When Fs = 1.5 Fs = τ · L / W · sin θ + Kh · W · cos θ
= [Μ × τ ₁ + (1−μ) × τ] × 203 / W · sin θ
+ Kh · W · cosθ
= [0.05 × 250.0 + (1−0.05) × 14.5]
× 203 / 2.951 × 0.16 × 17.000 × cos10
= 5.33 / 5.630
= 0.95.

  If Fs = 0.08 of the increase due to drainage is added to this, Fs = 1.03. Although the above calculation is based on a simple design, it is sufficient to know the improvement effect. In addition, the improvement effect by drainage is the effect by increasing the effective stress between the soil particles due to the lowering of the groundwater level, thereby improving the shear resistance of the embankment interface by 70%. There should be no.

  Moreover, naturally the effect of preventing liquefaction can be expected. In the above example, the combined use of drainage and consolidation is shown, but it is clear that only the drainage has a sufficient effect on the above principle, and it is omitted here because the drainage design may be performed as such.

  INDUSTRIAL APPLICABILITY The present invention can prevent landslide disasters such as residential land, factory construction land, roads, and the like that are created by valley embedding embankment on an inclined original ground.

Fig. 3 shows a built-up housing land that has been built by embankment on an inclined ground, and a drainage hole is formed in the boundary portion, (a) is a longitudinal sectional view, and (b) is a partial plan view. 1 shows a built-up residential land that has been built by embankment on an inclined ground, and a drainage hole is formed in a boundary portion on the downstream side, where (a) is a longitudinal sectional view and (b) is a partial plan view. Fig. 2 shows a built-up residential land that is formed by embankment on an original ground of an inclined land and has a ground improvement portion and a drain hole formed at a boundary portion, (a) is a longitudinal sectional view, and (b) is a partial plan view. Fig. 2 shows a built-up residential land that is built by embankment on a sloped ground and is alternately formed with ground improvement sections and drain holes at the boundary portion on the downstream side, (a) is a longitudinal sectional view, (b) is one FIG. Fig. 4 shows a built-up housing land that has been built by embankment on a sloped ground, and has a drainage hole on the downstream side and a ground improvement part on the upstream side, (a) is a longitudinal sectional view, (b) is one FIG. The operation | movement of a boring rod is shown, (a), (b) is a top view of the front-end | tip part of a boring rod. (A), (b) shows the solidification material injection pipe | tube for inject | pouring a solidification material in a ground, and is a longitudinal cross-sectional view of a front-end | tip part. A model ground is shown, (a) is a longitudinal cross-sectional view, (b) is a partial plan view. The model ground after ground reinforcement is shown, (a) is a longitudinal cross-sectional view, (b) is a partial plan view. The model ground after ground reinforcement is shown, (a) is a longitudinal cross-sectional view, (b) is a partial plan view. (A), (b) is a longitudinal cross-sectional view which shows an example of the conventional ground stabilization method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Original ground 2 Embankment 3 Drain hole 4 Ground improvement part 5 Boring hole 6 Boring rod 6a Drill head 6b Tapered blade 7 Casing 8 Solidification material injection pipe 9 Outer pipe 9a Check valve 9b Discharge port 10 Inner tube 10a Discharge port 11 Expansion Packer 12a Injection pipe 12b Injection pipe 12c Injection pipe 13 Sealed space 14 Expansion packer 15 Sealed space

Claims (9)

  A plurality of drilling holes are drilled in multiple rows in the inclination direction of the original ground along the boundary surface between the original ground and the embankment in the boundary portion between the original ground and the embankment built on the original ground. And the ground stabilization method characterized by making each said boring hole into a drainage hole.   A ground stabilization method for a valley-filled land created by embankment in a valley, wherein a plurality of boring holes are formed in a boundary portion between the original ground and a valley-filled land created on the original ground. A ground stabilization method characterized by drilling holes in a plurality of rows in the inclination direction of the original ground along the boundary surface between the original ground and the valley-filled ground, and using the boreholes as drainage holes.   The ground stabilization method according to claim 1 or 2, wherein the boring hole is formed by induction bending boring.   The ground stabilization method according to any one of claims 1 to 3, wherein the drainage hole is formed in a certain range of a downstream side portion of the original ground.   The ground stabilization according to any one of claims 1 to 4, wherein formation of a ground improvement part is used in combination with the drainage hole and the vicinity of the boundary surface between the ground and the embankment in the inclination direction of the ground. Method.   6. The ground improvement part is formed by injecting a solidified material into a boring hole drilled by bending boring or straight boring in an upstream part of a slope, or by stirring and mixing or high pressure injection. Ground stabilization method.   The ground improvement part is formed in the inclination direction of the original ground along the boundary surface between the original ground and the embankment between the drainage hole and the drainage hole on the downstream side. The ground stabilization method described in Crab.   The ground stabilization method according to any one of claims 1 to 7, wherein a retaining wall is constructed on a downstream side portion of the embankment.   The ground stabilization method according to any one of claims 1 to 8, wherein an anchor is constructed on the embankment and the tip of the anchor is fixed on the original ground.

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