JP6902144B2 - Slope ground flow control method and slope ground flow control structure - Google Patents

Description

The present invention relates to a method and a structure for suppressing the flow of slope ground.

On slope ground, the slope may slip and collapse due to heavy rain or the like. In addition, in soft sloped ground such as slag (slime) ground in the foundation bank at a mine slag accumulation site, flow may occur due to liquefaction and the accompanying decrease in ground strength during an earthquake. Therefore, on sloped ground, it is necessary to improve the stability of the ground during heavy rains and earthquakes.

As a method of suppressing landslides on slopes due to heavy rain, there are a method of installing a penetration prevention work on the ground surface to prevent the penetration of groundwater, a method of injecting a chemical solution, a method of placing piles, and the like to strengthen the ground. In addition, as a method of suppressing the flow of the slope during an earthquake, it is considered effective to improve the solidified ground by stirring the solidifying material such as cement in the original position to create a solidified body on the ground. A flow countermeasure structure including a side improved body formed on the side of the non-liquefied layer and landed or embedded in the non-liquefied layer has been proposed (see, for example, Patent Document 1).

In flat ground, as a method for suppressing liquefaction during an earthquake and improving stability, a method for improving the ground in a grid pattern is known (see, for example, Patent Documents 2 and 3).

Japanese Unexamined Patent Publication No. 2016-3514 JP-A-2002-302935 Japanese Unexamined Patent Publication No. 2009-185546

However, when the slope that requires stabilization measures during heavy rains and earthquakes is large, it is necessary to reduce the scope of improvement as much as possible from the viewpoint of reducing the cost of measures. At that time, the method of improving the ground in a grid pattern, which is used as a countermeasure against liquefaction of earthquakes, is effective, but the conventional design method of grid improvement is mainly based on the idea that liquefaction of unimproved parts is not allowed on the premise of flat ground. Therefore, it may not always be rational for slope ground where some liquefaction is allowed, such as a pit accumulation site, and there is concern that an unnecessary improvement range may be included in the stability of the slope.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to appropriately improve the ground over a wide range with a small amount of improved soil and to improve the stability of the slope ground. Flow control method and structure.

In order to achieve the above-mentioned object, the first invention is a method of suppressing the flow of the slope ground, in which the slope ground is improved at predetermined intervals in the direction parallel to the slope, and is a ground improvement portion. The step a for constructing the slope parallel wall is provided, the depth of some of the slope parallel walls is shallower than the depth of the other slope parallel walls, and the wall friction of the slope parallel walls suppresses the slip of the slope ground. This is a method for suppressing the flow of sloped ground.
The second invention is a method for suppressing the flow of the slope ground, which is a step a of performing ground improvement on the slope ground at predetermined intervals in a direction parallel to the slope and constructing a slope parallel wall which is a ground improvement portion. A step of forming a convex portion having a drainage hole penetrating from the upstream side surface to the downstream side surface of the slope ground on the surface layer of the slope ground is provided, and the slope is provided by wall friction of the slope parallel wall. This is a method for suppressing flow of sloped ground, which is characterized by suppressing slippage of the ground. Excess pore water pressure is the water pressure in the soil that rises during an earthquake, which is the cause of liquefaction.

In the first and second inventions, the slope parallel wall may be formed in a zigzag shape in a plan view.

When constructing a slope orthogonal wall, piles may be installed at the intersection of the slope parallel wall and the slope orthogonal wall, if necessary.
Further, the depth of at least a part of the slope orthogonal walls may be shallower than the depth of the slope parallel walls.
Further, it is desirable that the slope orthogonal wall be improved by a depth required for suppressing excess pore water pressure.

In the first and second inventions, the overburden portion that covers the surface layer of the slope ground may be provided by using the blown-up soil generated by the ground improvement. Fukiage soil is a mixture of soil and solidifying material that blows up to the ground when the solidifying material is agitated in the ground.
Further, in the second invention, if necessary, a convex portion is formed on the surface layer of the slope ground, and the convex portion is connected to the vicinity of the top of the slope parallel wall.

In the first and second inventions, the construction interval of the slope parallel wall and the wall thickness of the slope parallel wall are obtained from the adhesive force of the unimproved portion and the adhesive force of the ground improved portion of the composite ground. By setting the slip safety factor of the composite ground calculated using the adhesive force to exceed 1, it is possible to suppress the slip of the ground due to the restraining effect due to the wall friction of the parallel slope wall. Further, by providing the slope orthogonal wall in addition to the slope parallel wall, it is possible to suppress the vibration of the slope parallel wall at the time of an earthquake and suppress the liquefaction of the slope ground.

In the first and second inventions, the improvement depth of the slope parallel wall is set to the depth required for suppressing the excess pore water pressure and the slope slip, and the improvement depth of the slope orthogonal wall is set to the depth required for suppressing the excess pore water pressure. By doing so, the amount of improved soil can be reduced as compared with the conventional concept of grid-like improvement in which all the grid walls are set to the same depth. Further, if a pile is installed at the intersection of the slope orthogonal wall and the slope parallel wall, the slip resistance of the entire grid-like improvement range can be further suppressed by the bending resistance of the pile.

In the first and second inventions, if an overburden portion that covers the surface layer of the slope ground is provided using the blown-up soil generated by the ground improvement, the effect of suppressing liquefaction due to the load increment by the overburden portion can be obtained. The installation interval of parallel slope walls can be widened, and the amount of improved soil can be reduced. Further, if the convex portion formed on the surface layer of the slope ground is connected to the vicinity of the top of the slope parallel wall, the flow of earth and sand on the ground surface layer can be blocked by the convex portion.

The third invention is a structure that suppresses the flow of the slope ground, and the slope ground is provided with a slope parallel wall which is a ground improvement portion formed at a predetermined interval in a direction parallel to the slope, and a part of the slope. The slope ground flow suppression structure is characterized in that the depth of the parallel wall is shallower than the depth of the other slope parallel walls, and the sliding of the slope ground is suppressed by the wall friction of the slope parallel wall.
The fourth invention is a structure for suppressing the flow of the slope ground, wherein the slope ground is provided with a slope parallel wall which is a ground improvement portion formed at a predetermined interval in a direction parallel to the slope, and the slope parallel wall is provided. The feature is that the sliding of the slope ground is suppressed by the wall surface friction, and a convex portion having a drain hole penetrating the surface from the upstream side to the downstream side of the slope ground is formed on the surface layer of the slope ground. It is a flow suppression structure of the slope ground. Excess pore water pressure is the water pressure in the soil that rises during an earthquake, which is the cause of liquefaction.

In the third and fourth inventions, the slope parallel wall may be formed in a zigzag shape in a plan view.

In the third and fourth inventions, the construction interval of the slope parallel wall and the wall thickness of the slope parallel wall are obtained from the adhesive force of the unimproved portion and the adhesive force of the ground improved portion of the composite ground. By setting the slip safety factor of the composite ground calculated using the adhesive force to exceed 1, it is possible to suppress the slip of the ground due to the restraining effect due to the wall friction of the parallel slope wall. Further, by providing the slope orthogonal wall shallower than the depth of the slope parallel wall in addition to the slope parallel wall, it is possible to suppress the vibration of the slope parallel wall at the time of an earthquake and suppress the liquefaction of the slope ground. At this time, it is desirable that the slope orthogonal wall be improved by a depth required for suppressing excess pore water pressure.

In the third and fourth inventions, the improvement depth of the slope parallel wall is set to the depth required for suppressing the excess pore water pressure and the slope slip, and the improvement depth of the slope orthogonal wall is set to the depth required for suppressing the excess pore water pressure. By doing so, the amount of improved soil can be reduced as compared with the conventional concept of grid-like improvement in which all the grid walls are set to the same depth.

According to the present invention, it is possible to provide a method and a structure for suppressing flow of a sloped ground, which can appropriately improve the ground over a wide range with a small amount of improved soil and improve the stability of the sloped ground.

The figure which shows the outline of the slope ground 2 and the flow suppression structure 1. The figure which shows the outline of the slope ground 27 and the flow suppression structure 31. The figure which shows the outline of the flow suppression structure 31 constructed on the slope ground 27. Diagram showing other flow suppression structures The figure which shows the outline of the flow suppression structure 31c The figure which shows the outline of the flow suppression structure 31d The figure which shows the outline of the flow suppression structure 31e Diagram showing the outline of other flow suppression structures The figure which shows the example which formed the slope parallel wall in a zigzag shape in a plan view.

The first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing an outline of a slope ground 2 and a flow suppression structure 1. FIG. 1 (a) is a vertical sectional view of the slope ground 2 in the slope direction, and FIG. 1 (b) is a perspective view when measures are taken by the flow suppression structure 1 in the range A shown in FIG. 1 (a). (C) is a cross-sectional view of the unit 13 shown in FIG. 1 (b) in the direction orthogonal to the slope, and FIG. 1 (d) is an enlarged view of the range A shown in FIG. 1 (a). In FIGS. 1A and 1D, the right side of the figure is the upstream side in the sliding direction of the sliding layer 3, and the left side of the drawing is the downstream side. In FIG. 1B, the back side in the figure is the upstream side in the sliding direction of the sliding layer 3, and the front side in the drawing is the downstream side.

As shown in FIG. 1, the slope ground 2 includes a foundation ground 4 and a sliding layer 3. In the slope ground 2, as shown in FIG. 1B, a flow suppression structure 1 is formed in the sliding layer 3 as a countermeasure against the collapse of the slope 15 during heavy rain.

As shown in FIG. 1B, the flow suppression structure 1 is composed of a plurality of parallel slope walls 5 provided at predetermined intervals 7. The slope parallel wall 5 is arranged in a direction parallel to the slope 15 of the slope ground 2, that is, in a direction from the upstream side to the downstream side in the flow direction of the sliding layer 3.

In order to form the flow suppression structure 1, the sliding layer 3 is ground-improved in the direction parallel to the slope 15 of the slope ground 2, and a plurality of slope parallel walls 5 which are ground improvement portions are constructed. The distance 7 between the slope parallel walls 5 and the wall thickness 9 of the slope parallel walls 5 are obtained from the adhesive force Cs'of the unimproved portion that has not been ground-improved and the adhesive force Cc'of the slope parallel wall 5 that is the ground-improved portion. The slip safety factor of the composite ground is calculated using the adhesive force C'of the composite ground, and the slip safety factor is set to exceed 1.

When the unit 13 shown in FIG. 1 (b) is taken out from the slope ground 2, the cross section of the unit 13 in the direction orthogonal to the slope is as shown in FIG. 1 (c). The unit 13 is a composite ground composed of an unimproved portion and a slope parallel wall 5 which is a ground improved portion. The ratio a of the slope parallel walls 5 in one unit 13 is a = B / L, where B is the wall thickness 9 and L is the interval 7. Since one unit 13 is partially replaced by the slope parallel wall 5 which is a ground improvement portion, the resistance to arc slip is increased. If this is evaluated as the adhesive strength of the composite ground consisting of the unimproved portion of the adhesive strength Cs'and the ground improvement portion of the adhesive strength Cc', the slope parallel wall 5, the adhesive strength C'of the composite ground is calculated by the mathematical formula (1). expressed.

C'= aCc'+ (1-a) Cs' ... (1)

Further, as shown in FIG. 1D, when the soil mass in the sliding arc 11 is divided into a plurality of divided soil masses 17-1, 17-2, ..., 17-n, the sliding safety factor Fs of the composite ground is compounded. Ground adhesive force C', shear strength τ', length l of sliding side of divided soil mass 17, weight W of divided soil mass 17, pore water pressure u, width b of divided soil mass 17, sliding side of each divided soil mass 17 It is expressed by equation (2) using the angle α between the straight line connecting the midpoint and the center of the sliding circle and the vertical straight line, and each φ'shear resistance.

Fs = Στ'/ ΣWsinα = Σ {C'・ l + (W-ub) cosα ・ tanφ'} / ΣWsinα ... (2)

When determining the interval 7 of the slope parallel walls 5 and the wall thickness 9 of the slope parallel walls 5, B and L are tentatively determined with the wall thickness 9 as B and the interval 7 as L, and the adhesive strength of the composite ground is determined from Equation 1. Find C'. Then, the adhesive force C'of the composite ground is substituted into the mathematical formula 2 to confirm whether or not Fs> 1. If there is a margin in Fs, B and L are reduced and recalculation is performed to determine rational B and L.

The depth of the slope parallel wall 5 is determined in consideration of suppressing the excess pore water pressure of the sliding layer 3 and suppressing slipping. Excess pore water pressure is the water pressure in the soil that rises during an earthquake, which is the cause of liquefaction. The depth of the slope parallel wall 5 should be such that it lands on the foundation ground 4 or is rooted in the foundation ground 4 in order to suppress the slip of the sliding layer 3, but the slip obtained by the stability calculation described above is desirable. When the arc 11 is shallow, it can be a non-landing type.

As the ground improvement method, for example, a method in which the improvement depth can be arbitrarily set by a middle layer mixing treatment method such as a power blender (registered trademark) method is desirable.

In the first embodiment, by constructing the slope parallel wall 5 on the slope ground 2 to form the flow suppression structure 1, the sliding of the sliding layer 3 is suppressed by the wall friction of the slope parallel wall 5 during heavy rain, and the slope is sloped. The stability of the ground 2 can be improved.

Next, the second embodiment will be described. FIG. 2 is a diagram showing an outline of the slope ground 27 and the flow suppression structure 31. FIG. 2A is a longitudinal view of the slag accumulation site 19 in the slope direction. In FIG. 2A, the right side of the figure is the upstream side of the soft layer 23 in the flow direction, and the left side of the figure is the downstream side. FIG. 2B is a perspective view when measures are taken by the flow suppression structure 31 in the range B shown in FIG. 2A, and the soft layer 23 is omitted. In FIG. 2B, the back side of the figure is the upstream side in the flow direction, and the front side of the figure is the downstream side.

FIG. 3 is a diagram showing an outline of the flow suppression structure 31 constructed on the slope ground 27. FIG. 3A is a vertical sectional view of the sloped ground 27 in the direction orthogonal to the slope by arrows CC shown in FIG. 3B, which is a plan view of the sloped ground 27. In FIG. 3A, the back side of the figure is the upstream side of the soft layer 23 in the flow direction, and the front side of the figure is the downstream side. FIG. 3B is a plan view of the slope ground 27 on which the flow suppression structure 31 is constructed.

As shown in FIG. 2A, in the slag accumulation site 19, a foundation bank 25 is provided at the bottom of the non-liquefied layer 21 of the slope ground 27, and a soft layer 23 in which the accumulation is accumulated on the upstream side of the foundation bank 25. Is formed. On the soft layer 23 on the upstream side of the foundation embankment 25, an embankment may be built by the embankment 29. As seismic reinforcement of the slag accumulation site 19, a flow suppression structure 31 for suppressing flow due to liquefaction is formed in the soft layer 23 of the slope ground 27 as shown in FIG. 2 (b).

As shown in FIGS. 2B and 3, the flow suppression structure 31 has a plurality of slope parallel walls 33 constructed at predetermined intervals 37, and a plurality of slope orthogonalities constructed at predetermined intervals 39. It consists of a wall 35. The slope parallel wall 33 is arranged in a direction parallel to the slope of the slope ground 27, that is, in a direction from the upstream side to the downstream side in the flow direction of the soft layer 23. The slope orthogonal wall 35 is arranged in a direction substantially orthogonal to the slope of the slope ground 2, that is, in a direction orthogonal to the flow direction of the soft layer 23.

In order to form the flow suppression structure 31, first, the soft layer 23 is ground-improved in a direction parallel to the slope of the slope ground 27, and a plurality of slope parallel walls 33 are constructed. The construction interval and wall thickness of the slope parallel wall 33 are the adhesive force Cs'of the unimproved portion where the ground has not been improved and the adhesive force Cc of the slope parallel wall 33 which is the ground improved portion, as in the first embodiment. The slip safety factor of the composite ground is calculated using the adhesive force C of the composite ground obtained from'and, and the slip safety factor is set to exceed 1.

The depth 43 of the slope parallel wall 33 is determined in consideration of suppressing the excess pore water pressure of the soft layer 23 and suppressing slippage. The depth 43 of the slope parallel wall 33 is preferably set to the extent of landing on the non-liquefied layer 21 or rooted in the non-liquefied layer 21 in order to suppress slippage of the soft layer 23. If the obtained sliding arc is shallow, it can be made into a non-landing type.

After the slope parallel wall 33 is constructed, the soft layer 23 is ground-improved in a direction substantially orthogonal to the slope of the slope ground 27, and a plurality of slope orthogonal walls 35 are constructed. The depth 45 of the slope orthogonal wall 35 is determined only in consideration of suppressing the excess pore water pressure of the soft layer 23. The slope orthogonal wall 35 does not have to be joined to the slope parallel wall 33.

As the ground improvement method, for example, a method in which the improvement depth can be arbitrarily set by a middle layer mixing treatment method such as a power blender (registered trademark) method is desirable.

In the second embodiment, by forming the flow suppression structure 31 composed of the slope parallel wall 33 and the slope orthogonal wall 35 on the slope ground 27, the excess pore water pressure on the surface layer of the soft layer 23 which is easily liquefied during an earthquake is suppressed. Therefore, it is possible to prevent the surface of the slope ground 27 from shaking. Further, the sliding of the soft layer 23 of the slope ground 27 can be suppressed by the wall friction of the slope parallel wall 33, and the vibration of the slope parallel wall 33 can be suppressed by the slope orthogonal wall 35 to improve the stability of the slope ground 27. .. In the second embodiment, by determining the depth 45 of the slope orthogonal wall 35 in consideration of only suppressing the excess pore water pressure, the amount of improved soil can be reduced even when the ground is improved over a wide area.

FIG. 4 is a diagram showing another flow suppression structure. FIG. 4A shows a longitudinal view of the slope ground 27 on which the flow suppression structure 31a is formed in the direction orthogonal to the slope. In FIG. 4A, the back side of the figure is the upstream side of the soft layer 23 in the flow direction, and the front side of the figure is the downstream side. In the flow suppression structure 31 of the second embodiment, all the slope parallel walls 33 are set to such a depth that they land on the non-liquefaction layer 21, but the depth of the slope parallel walls 33 is not limited to this. If the excess pore water pressure of the soft layer 23 can be suppressed, and when the slope parallel wall 33 is constructed, the amount of the solidifying material added can be increased to increase the shear strength of the slope parallel wall 33 and the slippage can be suppressed. As shown in a), the depth of some of the slope parallel walls 33a can be made shallower than the depth of the other slope parallel walls 33 (the shallowest may be the same as the depth of the slope orthogonal walls 35).

FIG. 4B shows a plan view of the slope ground 27 on which the flow suppression structure 31b is formed. In the flow suppression structure 31 of the second embodiment, the slope parallel wall 33 is formed and then the slope orthogonal wall 35 is formed. However, as in the flow suppression structure 31b shown in FIG. 4 (b), the slope parallel wall 33b and the slope parallel wall 33b are formed. The slope orthogonal wall 35b may be integrally formed. Further, a haunch-like reinforcing portion 41 may be formed at a corner portion formed by the slope parallel wall 33b and the slope orthogonal wall 35b.

Next, a third embodiment will be described. FIG. 5 is a diagram showing an outline of the flow suppression structure 31c according to the third embodiment. FIG. 5A shows a longitudinal view of the slope ground 27 on which the flow suppression structure 31c is formed in the direction orthogonal to the slope. In FIG. 5A, the back side of the figure is the upstream side of the soft layer 23 in the flow direction, and the front side of the figure is the downstream side. FIG. 5B shows a flowchart for optimizing the installation interval 37c of the slope parallel wall 33c and the thickness 49 of the overburden portion 47.

In order to form the flow suppression structure 31c on the slope ground 27, first, as shown in FIG. 5A, the ground is improved in the direction parallel to the slope, and a plurality of slope parallel walls 33c are constructed. The construction interval and wall thickness of the slope parallel wall 33c are the same as in the first embodiment, the adhesive force Cs'of the unimproved portion where the ground has not been improved and the adhesive force Cc of the slope parallel wall 33c which is the ground improved portion. The slip safety factor of the composite ground is calculated using the adhesive force C of the composite ground obtained from'and, and the slip safety factor is set to exceed 1.

The depth of the slope parallel wall 33c is determined in consideration of suppression of excess pore water pressure and suppression of slippage of the soft layer 23. The depth of the slope parallel wall 33c is preferably set to the extent of landing on the non-liquefied layer 21 or rooted in the non-liquefied layer 21 in order to suppress slippage of the soft layer 23, but it can be obtained by stable calculation. If the sliding arc is shallow, it can be a non-landing type.

Next, the ground is improved in a direction substantially orthogonal to the slope, and a plurality of slope orthogonal walls 35c are constructed. The depth of the slope orthogonal wall 35c is determined only by considering the suppression of excess pore water pressure in the soft layer 23.

After the slope orthogonal wall 35c is constructed, the overburden portion 47 covering the surface layer of the slope ground 27 is installed by using the blown up soil generated by the ground improvement when the slope parallel wall 33c and the slope orthogonal wall 35c are constructed. When installing the overburden portion 47, the blown-up soil may be used as it is, or the hardened blown-up soil may be crushed and cement or the like may be added and used. When the blown-up soil is used as it is, the overburden portion 47 may be compacted for improvement. The overburden portion 47 formed by rolling or adding cement or the like can be used as a work scaffold for heavy machinery.

When forming the flow suppression structure 31c, the installation interval 37c of the slope parallel wall 33c and the thickness 49 of the overburden portion 47 are optimized according to the flowchart shown in FIG. 5B. In order to perform optimization, first, the installation interval 37c of the slope parallel wall 33c is set (step 101), and the liquefaction determination of the soft layer 23 is performed (step 103). If it is determined to be liquefied in step 103, the process returns to step 101.

If it is determined in step 103 that liquefaction does not occur, the amount of blown up soil generated by ground improvement is calculated (step 105), the thickness 49 of the overburden portion 47 is set (step 107), and the soft layer 23 Liquefaction determination is performed (step 109). If it is determined in step 109 that the strength of the soft layer 23 has a margin, the installation interval 37c of the slope parallel wall 33c is reset (step 111), and the process returns to step 105. If it is determined in step 109 that there is no margin, it is determined that the most rational installation interval 37c of the slope parallel wall 33c and the thickness 49 of the overburden portion 47 have been obtained, and the optimization is terminated.

In the third embodiment, the flow suppression structure 31c having the slope parallel wall 33c and the slope orthogonal wall 35c is formed on the slope ground 27, and then the overburden portion 47 is installed on the surface layer of the slope ground 27. Excessive pore water pressure in the surface layer of the soft layer 23, which tends to liquefy during an earthquake, can be suppressed to prevent the surface of the slope ground 27 from shaking. Further, the sliding of the soft layer 23 of the slope ground 27 can be suppressed by the wall friction of the slope parallel wall 33c, and the vibration of the slope parallel wall 33c can be suppressed by the slope orthogonal wall 35c to improve the stability of the slope ground 27. ..

In the third embodiment, the installation interval of the lattice wall can be further widened by increasing the liquefaction resistance due to the overburden portion 47. In the third embodiment, the installation interval 37c of the slope parallel wall 33c and the installation interval 37c of the slope parallel wall 33c are optimized by optimizing the installation interval 37c of the slope parallel wall 33c and the thickness 49 of the overburden portion 47 according to the flowchart shown in FIG. Can be expanded and the amount of improved soil can be reduced.

Next, a fourth embodiment will be described. FIG. 6 is a diagram showing an outline of the flow suppression structure 31d according to the fourth embodiment. FIG. 6A is a vertical sectional view of the sloped ground 27 in the direction orthogonal to the slope by arrows DD shown in FIG. 6B, which is a plan view of the sloped ground 27. In FIG. 6A, the back side of the figure is the upstream side of the soft layer 23 in the flow direction, and the front side of the figure is the downstream side. FIG. 6B is a plan view of the slope ground 27 on which the flow suppression structure 31d is constructed.

In order to form the flow suppression structure 31d on the slope ground 27, first, as shown in FIG. 6, the ground is improved in the direction parallel to the slope, and a plurality of slope parallel walls 33d are constructed. The construction interval and wall thickness of the slope parallel wall 33d are the adhesive force Cs'of the unimproved portion where the ground has not been improved and the adhesive force Cc of the slope parallel wall 33d which is the ground improved portion, as in the first embodiment. The slip safety factor of the composite ground is calculated using the adhesive force C of the composite ground obtained from'and, and the slip safety factor is set to exceed 1. The depth of the slope parallel wall 33d is determined in consideration of suppression of excess pore water pressure and suppression of slippage of the soft layer 23.

Next, the ground is improved in a direction substantially orthogonal to the slope, and a plurality of slope orthogonal walls 35d are constructed. The depth of the slope orthogonal wall 35d is determined only by considering the suppression of excess pore water pressure in the soft layer 23.

After that, the pile 51 is installed at the intersection of the slope parallel wall 33d and the slope orthogonal wall 35d. The specifications of the pile 51 are such that the slip of the soft layer 23 can be suppressed. It is desirable that the depths of the slope parallel wall 33d and the pile 51 are set to the extent that they land on the non-liquefaction layer 21 or are rooted in the non-liquefaction layer 21, but the sliding arc obtained by the stability calculation is If it is shallow, it can be a non-bottom type.

In the fourth embodiment, by forming a flow suppression structure 31d having a slope parallel wall 33d and a slope orthogonal wall 35d on the slope ground 27, excessive pore water pressure on the surface layer of the soft layer 23, which is easily liquefied during an earthquake, is suppressed. Therefore, it is possible to prevent the surface of the slope ground 27 from shaking. Further, the sliding of the soft layer 23 of the slope ground 27 is suppressed by the wall friction of the slope parallel wall 33d and the pile 51, and the vibration of the slope parallel wall 33d is suppressed by the slope orthogonal wall 35d to improve the stability of the slope ground 27. be able to.

In the fourth embodiment, the depth of the slope parallel wall 33d and the slope orthogonal wall 35d is determined only by considering the suppression of excess pore water pressure, so that the amount of improved soil is reduced even when the ground is improved over a wide area. it can.

Next, a fifth embodiment will be described. FIG. 7 is a diagram showing an outline of the flow suppression structure 31e according to the fifth embodiment. FIG. 7A is a vertical sectional view of the sloped ground 27 in the direction orthogonal to the slope by arrows EE shown in FIG. 7C, which is a plan view of the sloped ground 27. In FIG. 7A, the back side of the figure is the upstream side of the soft layer 23 in the flow direction, and the front side of the figure is the downstream side. FIG. 7 (b) is a vertical sectional view of the slope ground 27 in the slope direction by arrows FF shown in FIG. 7 (c). In FIG. 7B, the right side of the figure is the upstream side of the soft layer 23 in the flow direction, and the left side of the figure is the downstream side. FIG. 7C is a plan view of the slope ground 27 on which the flow suppression structure 31e is constructed.

In order to form the flow suppression structure 31e on the slope ground 27, first, as shown in FIG. 7, the ground is improved in the direction parallel to the slope, and a plurality of slope parallel walls 33e are constructed. The construction interval and wall thickness of the slope parallel wall 33e are the adhesive force Cs'of the unimproved portion where the ground has not been improved and the adhesive force Cc of the slope parallel wall 33e which is the ground improved portion, as in the first embodiment. The slip safety factor of the composite ground is calculated using the adhesive force C of the composite ground obtained from'and, and the slip safety factor is set to exceed 1.

The depth of the slope parallel wall 33e is determined in consideration of suppression of excess pore water pressure and suppression of slippage of the soft layer 23. The depth of the slope parallel wall 33e is preferably set to the extent of landing on the non-liquefied layer 21 or rooted in the non-liquefied layer 21 in order to suppress slippage of the soft layer 23, but it can be obtained by stable calculation. If the sliding arc is shallow, it can be a non-landing type.

Next, the ground is improved in a direction substantially orthogonal to the slope, and a plurality of slope orthogonal walls 35e are constructed. The depth of the slope orthogonal wall 35e is determined only in consideration of suppressing the excess pore water pressure of the soft layer 23.

After that, a convex portion 57 is formed on the surface layer of the slope ground 27 along the top of the slope orthogonal wall 35e. The convex portion 57 is connected to the slope parallel wall 33e by an anchor 59 embedded in the vicinity of the top before the slope parallel wall 33e is cured. In the slope ground 27 of the slag accumulation site, water such as rainfall may flow from the upstream along the surface layer as shown by the arrow J in FIG. 7 (c). The convex portion 57 has a drain hole 61 penetrating from the upstream side surface to the downstream side surface of the slope ground 27. The drain hole 61 is arranged with an inclination so that water flowing from the upstream of the slag collection site flows to the side of the slag collection site (right side and left side of FIG. 7C).

In the fifth embodiment, by forming a flow suppression structure 31e having a slope parallel wall 33e and a slope orthogonal wall 35e on the slope ground 27, excessive pore water pressure on the surface layer of the soft layer 23, which is easily liquefied during an earthquake, is suppressed. Therefore, it is possible to prevent the surface of the slope ground 27 from shaking. Further, the sliding of the soft layer 23 of the slope ground 27 can be suppressed by the wall friction of the slope parallel wall 33e, and the vibration of the slope parallel wall 33e can be suppressed by the slope orthogonal wall 35e to improve the stability of the slope ground 27. .. Further, by forming the convex portion 57 on the surface layer of the slope ground 27 along the top of the slope orthogonal wall 35e, it is possible to reduce the amount of water that escapes to both sides of the mine accumulation site and permeates the slope ground 27. At the same time, when the sediment on the surface layer of the slope ground 27 flows as shown by the broken line 63 in FIG. 7B, the fluidized sediment can be blocked by the convex portion 57.

In the fifth embodiment, the depth of the slope orthogonal wall 35e is determined only by considering the suppression of the excess pore water pressure of the soft layer 23, so that the amount of improved soil can be reduced even when the ground is improved over a wide area. ..

FIG. 8 is a diagram showing an outline of another flow suppression structure. FIG. 8 (a) is a vertical sectional view of the slope ground 2 in the direction orthogonal to the slope by the arrows GG shown in FIG. 8 (b), which is a plan view of the slope ground 27. In FIG. 8A, the back side of the figure is the upstream side of the soft layer 23 in the flow direction, and the front side of the figure is the downstream side. FIG. 8B is a plan view of the slope ground 27 on which the flow suppression structure 31f is constructed.

In the fifth embodiment, the convex portion 57 is formed along the top of the slope orthogonal wall 35e, but the arrangement of the convex portion 57 is not limited to this. As in the flow suppression structure 31f shown in FIGS. 8A and 8B, the convex portion 57f may be arranged on the surface layer of the slope ground 27 so as to have a mountain shape in a plan view. In the slope ground 27 of the slag accumulation site, water such as rainfall may flow from the upstream along the surface layer as shown by the arrow H in FIG. 8 (b). By forming the convex portion 57f, water flowing from the upstream flows along the convex portion 57f to the side of the slag collection site (right side and left side in FIG. 8B). As shown in FIG. 8A, the convex portion 57f is connected by an anchor 59f near the top of the slope parallel wall 33f at the intersection with the slope parallel wall 33f. The convex portion 57f has a drain hole 61f that penetrates from the upstream side surface to the downstream side surface of the slope ground 27. The drain hole 61f is arranged with an inclination so that the water flowing from the upstream of the slag collection site flows to the side of the slag collection site.

FIG. 8C is a plan view of the slope ground 27 on which the flow suppression structure 31 g is constructed. As in the flow suppression structure 31g shown in FIG. 8C, the convex portion 57g may be arranged so as to have a valley shape in a plan view. By forming the convex portion 57g, water flowing from the upstream flows along the convex portion 57g to the center of the slag accumulation field as shown by the arrow I in FIG. 8 (c). The convex portion 57g is connected by an anchor (not shown) near the top of the slope parallel wall 33g at the intersection with the slope parallel wall 33g. The convex portion 57g has a drain hole 61g penetrating from the upstream side surface to the downstream side surface of the slope ground 27. The drain hole 61 g is arranged so that the water flowing from the upstream of the slag collection site flows to the downstream side so that the water does not collect in the bent portion of the convex portion 57 g.

In the above-described embodiment, the slope parallel wall is constructed and then the slope orthogonal wall is constructed, but the construction order is not limited to this. As in the example shown in FIG. 4B, the slope parallel wall and the slope orthogonal wall may be integrally constructed. The slope parallel wall may be constructed after the slope orthogonal wall is constructed. Construction may be performed in order from the downstream side regardless of the direction of the lattice wall.

Further, in the examples shown in FIGS. 1 to 8, the slope parallel wall is formed linearly in a plan view, but the shape of the slope parallel wall is not limited to this. FIG. 9 is a diagram showing an example in which a parallel slope wall is formed in a zigzag shape in a plan view.

FIG. 9A is a plan view of the slope ground 2 on which the flow suppression structure 1a is constructed. As shown in FIG. 9A, in order to suppress slippage of the slope ground 2 due to heavy rain or the like, zigzag-shaped slope parallel walls 5a may be constructed at predetermined intervals in a plan view to form a flow suppression structure 1a. The slope parallel wall 5a is formed in a zigzag shape with a predetermined swing width on the left and right sides of the axis 65 about the axis 65 parallel to the slope in a plan view.

FIG. 9B is a plan view of the slope ground 27 on which the flow suppression structure 31h is constructed. As shown in FIG. 9B, in order to suppress liquefaction of the slope ground 27 due to an earthquake or the like, zigzag-shaped slope parallel walls 33h are constructed at predetermined intervals in a plan view, and together with the slope orthogonal wall 35h. The flow suppression structure 31h may be used. The slope parallel wall 33h is formed in a zigzag shape with a predetermined swing width on the left and right sides of the shaft 67 about the shaft 67 parallel to the slope in a plan view. As described above, in the present invention, the slope parallel wall may be formed with a slight inclination as long as it is formed substantially parallel to the slope as a whole.

Although the embodiments of the present invention have been described above with reference to the attached drawings, the technical scope of the present invention does not depend on the above-described embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the technical ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs.

1, 1a, 31, 31a, 31b, 31c, 31d, 31e, 31f, 31g, 31h ………… Flow suppression structure 2, 27 ………… Slope ground 3 ………… Sliding layer 4 ………… Foundation ground 5, 5a , 33, 33a, 33b, 33c, 33d, 33e, 33f, 33g, 33h ……… Slope parallel walls 7, 37, 39, 37c ……… Spacing 9 ……… Wall thickness 11 ……… Sliding arc 15… … Slopes 17-1, 17-2,…, 17-n ……… Divided soil mass 19 ………… Mining pile 21 ……… Non-liquefied layer 23 ……… Soft layer 25 ……… Foundation bank 41 …… … Reinforcement part 43, 45 ……… Depth 47 ……… Overburden part 51 ……… Pile 57, 57f, 57g ……… Convex part 61 ……… Drain hole

Claims (12)

It is a method of suppressing the flow of the slope ground,
The slope ground is provided with a step a of performing ground improvement at predetermined intervals in a direction parallel to the slope and constructing a slope parallel wall which is a ground improvement portion.
The depth of some of the slope parallel walls is shallower than the depth of other of the slope parallel walls,
A method for suppressing flow of slope ground, which comprises suppressing slippage of the slope ground by friction on the wall surface of the slope parallel wall. It is a method of suppressing the flow of the slope ground,
Step a of performing ground improvement on the slope ground at predetermined intervals in the direction parallel to the slope and constructing a slope parallel wall which is a ground improvement part.
A step of forming a convex portion having a drainage hole penetrating the surface from the upstream side to the downstream side of the slope ground on the surface layer of the slope ground.
Equipped with
A method for suppressing flow of slope ground, which comprises suppressing slippage of the slope ground by friction on the wall surface of the slope parallel wall. The predetermined spacing and the wall thickness of the slope parallel wall are calculated by using the adhesive force of the composite ground obtained from the adhesive force of the unimproved portion without ground improvement and the adhesive force of the ground improved portion. The method for suppressing flow of sloped ground according to claim 1 or 2, wherein the slip safety factor of the ground is set to exceed 1. The method for suppressing flow of slope ground according to claim 1, wherein the slope parallel wall is improved to a depth required for suppressing excess pore water pressure and suppressing slippage of the slope. The slope ground is further provided with a step b of performing ground improvement at predetermined intervals in a direction substantially orthogonal to the slope and constructing a slope orthogonal wall which is a ground improvement portion.
The method for suppressing flow of slope ground according to any one of claims 1 to 4, wherein the liquefaction of the slope ground is suppressed by the slope orthogonal wall. The method for suppressing flow of slope ground according to claim 5, wherein the slope orthogonal wall is improved by a depth required for suppressing excess pore water pressure. It has a structure that suppresses the flow of the slope ground,
The slope ground is provided with a slope parallel wall, which is a ground improvement portion formed at predetermined intervals in the direction parallel to the slope.
The depth of some of the slope parallel walls is shallower than the depth of other of the slope parallel walls,
A flow suppression structure for slope ground, characterized in that slippage of the slope ground is suppressed by wall friction of the slope parallel wall. It has a structure that suppresses the flow of the slope ground,
The slope ground is provided with a slope parallel wall, which is a ground improvement portion formed at predetermined intervals in the direction parallel to the slope.
The wall friction of the slope parallel wall suppresses the slip of the slope ground,
A flow suppression structure for a sloped ground, characterized in that a convex portion having a drainage hole penetrating from an upstream side surface to a downstream side surface of the sloped ground is formed on the surface layer of the sloped ground. The predetermined spacing and the wall thickness of the slope parallel wall are calculated by using the adhesive force of the composite ground obtained from the adhesive force of the unimproved portion without ground improvement and the adhesive force of the ground improved portion. The flow suppression structure for sloped ground according to claim 7 or 8, wherein the slip safety factor of the ground is set to exceed 1. The flow suppression structure for slope ground according to claim 7, wherein the slope parallel wall is formed to a depth required for suppressing excess pore water pressure and suppressing slippage of the slope. The slope ground is further provided with slope orthogonal walls, which are ground improvement portions formed at predetermined intervals in a direction substantially orthogonal to the slope.
The depth of at least a part of the slope orthogonal walls is formed to be shallower than the depth of the slope parallel walls.
The flow suppression structure for slope ground according to any one of claims 7 to 10, wherein the liquefaction of the slope ground is suppressed by the slope orthogonal wall. The flow suppression structure for slope ground according to claim 11, wherein the slope orthogonal wall is formed to a depth required for suppressing excess pore water pressure.

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