JP2013044222A - Ground slope corrosion prevention method of grating crib bottom - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grating crib work method for attaining a slope face collapse prevention construction by constructing grating cribs on a cutting slope and crimping the grating cribs with a ground anchor, and for preventing a gap from being generated on a grating crib bottom caused by corrosion of the cutting slope with rainfall or frozen soil within a construction term prior to constructing slope protection (slope planting or the like).SOLUTION: According to a ground slope corrosion prevention method of a grating crib bottom, after a cutting slope 4 is formed, a sediment outflow prevention sheet 1 is laid immediately and covered with a lath spread wire net 2 to prevent the cutting slope from being corroded with rainfall or frozen soil, thereby proceeding with grating crib work thereafter while preventing concrete placement, curing, drilling 10, insertion of an anchor 8, anchor tension work and the like of a grating crib construction 6 from being affected by slope corrosion caused by rainfall or frozen soil.

Description

  The present invention relates to a ground slope erosion prevention method on the bottom of a method frame related to preventing a cut slope from being eroded by freezing and thawing, rainfall, or the like during the construction period of an anchor method frame work.

  The construction period of the concrete frame, etc. on the cut slope so far, cut the slope and then tighten the anchor, finish the tightening work of the ground with the frame, and implement slope protection work (greening etc.) It takes about six months for the standard construction period to be applied, and the cut slope is eroded due to natural phenomena such as heavy rain and frost heave during this period. The main factor is that it is necessary to complete the following construction before the slope protection work (greening, etc.) is performed after cutting the slope, and the time is prolonged.

(1) Cover the cut slope with a lath wire mesh, (2) then assemble the reinforcing bars of the frame, (3) place concrete on the frame, (4) concrete curing period, (5) then insert the anchor Drilling holes, (6) grout injection, (7) and anchor insertion, (8) grout curing period, (9) anchor tension work, etc.
During this work period, the erosion of the cut slope progresses, and a gap is generated between the bottom face of the frame and the ground slope, and the role function of tightening the ground with the tensile force of the anchor is greatly reduced. For this reason, when eroded as shown in FIG. 2, a gap h is generated between the bottom of the concrete method frame and the ground slope, and it is necessary to repair with filled concrete, which requires much labor. .

  As a slope protection method using a conventional frame, a method disclosed in Patent Document 1 “Reinforcement Slope Method” has been proposed. In this technology, underground anchors are placed on the slope ground at predetermined intervals, and a vegetation sheet and a protective net are laid on the slope, and the frame-like connecting member is vertically and horizontally between the anchor tension members. The vegetation sheet is inexpensive and can be easily constructed in a short construction period. And it is said that the vegetation can be improved by preventing the collapse and runoff of the topsoil with the protection net.

  Because of this cross-sectional structure, the anchor is not expected to have a ground tightening effect, and has a cross-sectional structure to the extent that a frame-shaped connecting member is connected. This slope protection method is a cut method. In view of the scale of anchors, holding metal fittings, etc., which consists of steel material with a thin vegetation sheet with a thickness attached to the seed frame between the bottom of the frame and the ground surface. It is a slope protection method that mainly focuses on the prevention of loosening, falling off and greening in the field situation where the entire slope is relatively stable, not the cross-sectional structure of the slope frame assuming the landslide surface of the slope. . Therefore, there is no function to close the bottom surface of the frame and the slope ground, to transmit the anchor force to the ground and to tighten the slip layer like the concrete method frame for anchors, and it is not a cross-sectional structure of the anchor method frame method etc. .

Patent No. 4157548 “Reinforcement Reinforcement Slope Method”

The concrete frame construction method with a wide frame width is a cross-sectional structure in which the bottom of the frame and the ground slope are brought into close contact with the anchor's tensile force and the weak layer of the slip layer is tightened. Laying a soft sheet with a thickness necessary for breeding on the cut slope will not only lower the function of the anchor work but also a concrete method with a wide frame width. If it is laid on the bottom surface of the frame, the area where the expensive planting mat is exposed is small, and the effect of the planting mat is reduced, resulting in an uneconomical planting situation. For these reasons, the erosion countermeasures on the cutting slope of anchor work by using the concrete frame of on-site concrete and the pressure plate of the secondary product, etc. until now have been mainly aimed at speeding up the construction work of each work type and reducing the work period. It corresponds with the method.
The problem to be solved by the present invention is to solve these problems in the past, and for the construction period until the greening construction such as slope protection is carried out, it is due to rain and frost heaving with an economical and easy construction method The purpose is to provide a method for preventing erosion of the ground slope at the bottom of the method frame to prevent slope erosion.

The gist of the present invention will be described in the order of construction.
1) A cut slope and ground slope 4 are formed, and at the same time, a landslide prevention sheet 1 for preventing erosion of the ground slope is laid and covered with a lath wire mesh 2, and the anchor pins 5 are spaced at intervals according to the slope slope, etc. Set up and form a method to prevent erosion of the ground slope below the bottom of the method frame.
2) It is possible to draw the layout of the concrete frame etc. on the surface of the sheet for preventing sediment outflow in full size. Mark the vertical dimension 6b and the horizontal dimension 6a to secure the frame width W and position the anchor 8 Set.
3) A formwork 9 and the like are installed according to the dimension drawing drawn on the surface of the sheet for preventing sediment discharge, and the rebar 7 is assembled and processed.
4) An anchor hole 10 is secured in the mold 9 and the like, and concrete for the frame is placed to form a frame height H in which the sheet 1 and the lath wire mesh 2 are integrated. .
5) After the concrete frame is hardened, the hole 10 is worked and the anchor 8 is inserted and fixed by the grout 11.
6) After the grout 11 is hardened, the anchor 8 is tensioned and completed.
7) In addition, when slope greening or mortar spraying is carried out after the completion of the frame and anchor work (the part excluding the frame width W in the range of 6a x 6b), a thick layer base material or the like is used depending on the site. It is possible to spray a lath-strung wire net or mortar.

  The purpose of laying the sediment runoff prevention sheet 1 is to prevent the erosion of the cut slope, the cross-sectional shape is water permeable and relaxes frost heave, and roots such as plants pass through the slope other than the bottom of the frame, or It consists of a material that has a cross-sectional structure with holes and meshes through which seeds sprinkled on the slope ground germinate and leaves can grow through. If the cut slope is laid with a non-permeable vinyl sheet with no holes or mesh, it is the best material when considering only rain and frost heave, but the bottom of the frame and the slope ground are separated. The friction coefficient is reduced, the frame becomes cheaper, and when there is spring water from the soft ground, it becomes difficult to discharge the spring water to the sheet surface, and the sheet flows on the cutting slope on the back of the sheet, If is in close contact with the cut slope, water pools and water pressure are generated by spring water, forming a water passage, and the slope is eroded and is in a dangerous state.

Next, the cause of the erosion of the cut slope will be described with reference to FIGS.
If the earth and sand runoff prevention sheet 1 with holes and meshes formed on the sheet is closely attached to the cut slope, rainfall will penetrate the ground, but the thickness 1H of the earth and sand runoff prevention sheet 1 will impede the flow rate of rainwater on the ground surface. become. In the case of FIG. 6, since the mesh | interval 1a is large, the flowing water Vb will be comparatively quick, and if the soil particle on the ground surface is small, it will lead out. On the other hand, when the mesh interval 1b of the sediment discharge prevention sheet 1 in FIG. 7 is the same as the thickness 1H of the sediment discharge prevention sheet 1, the flow velocity Vc is inhibited and the flow is decelerated from Vb and the soil particles are small. But it will prevent the outflow.

  The size of the holes and meshes of the earth and sand spill prevention sheet 1 is preferably about 1 mm to 2 mm from the course of experiments so far, although it depends on the grain shape of the soil. Moreover, if it is the shape of a hole and a mesh of this extent, the root hair of planting will also enter, or the seed 3 when sprinkled on the ground surface will germinate and a leaf can extend. In order to prevent frost columns due to the frost heave phenomenon in winter, if the hole or mesh of the sheet is about 1 mm to 2 mm, the evaporation of water vapor on the ground surface becomes clogged with clogging and the cold air does not directly touch the ground slope, thus keeping warm. Can keep. Also, when placing concrete, the mortar penetrates and is in close contact with the ground slope. The thickness of the earth and sand outflow prevention sheet 1 is about 1 mm to 2 mm although it depends on the shape of the soil particles on the ground.

With such a cross-sectional structure, even on steep slopes, the flow velocity flowing on the surface of the ground slope due to rainfall is hindered by the thickness of the hole and mesh of the sheet, and the main water flows mainly on the upper surface from the sheet surface. This will prevent the outflow of soil particles on the surface. In addition, since the size of the mesh such as a lath-strung wire mesh (mesh 2a × 2b = about 50 mm × 50 mm) and the wire thickness of the wire mesh (about 2 mm to 5 mm), the thickness of the mesh and the steel wire If the ratio becomes 10 times or more and the earth and sand spill prevention sheet 1 is not laid on the cut slope, the ground slope will be exposed to the flowing water and corroded in the lath wire mesh.
In addition, when the thickness 1H of the sediment discharge prevention sheet 1 becomes about 10 mm or more, the water pressure rises and flows under the sediment discharge prevention sheet 1 and erodes the ground slope. Therefore, the thickness and thickness of the sediment discharge prevention sheet 1 are increased. 1H shall be around 1 mm to 2 mm.

  In this way, the cut slope in the anchor method frame work will be left for 4 to 6 months unless the sediment prevention sheet 1 is laid, and erosion of the ground slope at the bottom of the method frame due to rain, frost heave, etc. As a result, the function of the anchor frame method will be greatly impaired.

  The construction period by the anchor method frame method, etc., is long because the construction period from the formation of the cut slope to the protection of the entire slope by greening or cement spraying within the method frame is long. It is often eroded by frost heaving, etc., and requires ground protection such as a frame work. In the present invention, the erosion prevention of the cut slope within this period is covered by covering with the earth and sand outflow prevention sheet 1 which is economical and has good workability.

  Especially when the cut slope is concave, rainfall accumulates and flows down the cut slope, scouring the bottom of the frame and deepening the slope, making restoration work extremely difficult and extremely difficult. It is a cost. For this reason, laying the earth and sand outflow prevention sheet 1 on the cutting slope at an early stage leads to a safety measure for the anchor frame and an easy site management method.

In the explanatory sectional view of the anchor method frame work of the present invention, a sediment discharge prevention sheet is laid on the cut slope 4 and covered with a lath wire mesh 2, and a concrete method frame width W and height H are formed thereon, and the anchor 8 is used. It is sectional drawing showing the condition which has fixed the concrete method frame work to the ground slope. In the cross-sectional view of the anchor method frame work so far, since there is no earth and sand outflow prevention sheet 1, the ground slope is scoured by rain and frost heaving during the construction period until the slope work such as revegetation work is not yet implemented This is an example of a situation where a gap h is generated between the bottom of the frame and the ground slope. In the case where the cross-sectional structure shown in FIG. 1 is reduced in plan view and arranged on the cut slope, the frame spacing and the like are shown as a horizontal width 6a and a vertical width 6b, respectively, and the dimensions are in the range of 1 m to 3 m, respectively. is there. In the enlarged plan view within the range of the horizontal width 6a and the vertical width 6b shown in FIG. 3, the lath wire mesh is shown as the horizontal width 2a and the vertical width 2b, and the dimensions are in the range of about 30 mm to 50 mm, respectively. 4 shows a cross-sectional view of the position a to a in FIG. 4, and the thickness 2H of the lath wire mesh is in a range of about 2 mm to 5 mm. It shows the situation where there is rainfall and rainwater flows on the ground slope 4 and flows down to the water surface 9, and is an enlarged cross-sectional view of the range 2a in the cross-sectional view of FIG. 5, and the flow above the water surface 9 is expressed by a vector Va. Vb below the water level shows the flow when the mesh interval 1a of the sediment runoff prevention sheet 1 is about 5 times the thickness 1H, the mesh interval 1a is about 10 mm, and the soil particles on the ground slope If it is small, it is scoured and presents a situation of concern for erosion. 6 is the same drawing as FIG. 6, but the cross-sectional structure when the mesh interval 1a of the sediment runoff prevention sheet 1 is an interval of about 1 time or more of the thickness 1H because the ground slope particles are small and there is a risk of erosion by running water. The flowing water Vc shows a slow flow, and the mesh interval 1b shows about 2 mm, which is a standard embodiment. Moreover, when it is such a mesh shape, the seed 3 of the plant spread on the cut slope is likely to be settled in the mesh. The whole cross-sectional view of a cut slope is shown, and the embodiment of the ground slope erosion prevention construction method of the bottom face of the method frame which applied this invention to the cut slope is shown.

  Many slopes and mats have been developed for the slope protection method, etc., but protection of the cut slope during the construction period until the slope is stabilized by the anchor frame construction Until now, heavy rain and snowfall etc. have been judged daily by weather forecasts etc. and have been working to cover the construction section with temporary vinyl sheets etc., but due to being blown away by strong winds etc., daily removal cover work Is a tough job. In this situation, the sediment prevention sheet 1 is laid on the ground slope and covered with a lath wire mesh, and this is handled in the main work. This leads to a construction method that stabilizes the ground slope and improves safety management.

  In the figure, reference numeral 1 denotes an earth and sand outflow prevention sheet which is the main body of the present invention, and the material is a woven material such as a synthetic resin sheet or a hemp sheet. Reference numeral 2 denotes a lath tension, and the material is a net made of synthetic resin or steel wire, and a method of covering immediately after laying the sheet 1 for preventing sediment outflow. 3 is a seed of a plant, and when the cut slope is relatively soft, it is sprayed before or after laying the sheet 1 for preventing sediment outflow to prepare for greening. 4 shows the ground slope below the cut slope and bottom of the frame. An anchor pin 5 is an anchor which is fixed by an anchor pin after the lath wire mesh 2 is laid. The anchor 5 is made of a steel rod, and the thickness and length are set in accordance with the soil texture of the cut slope, and driven by a hammer or the like. Reference numeral 6 denotes a legal frame, and the material used in the field is concrete. However, an independent pressure plate may be made of concrete or steel. 7 is a reinforcing bar within the legal framework. 8 is an anchor that fixes the frame and tightens the ground. The length is set according to the soil quality. Reference numeral 12 denotes a contraction device that promotes the anchor function.

The purpose and sectional structure of the sheet 1 for preventing sediment discharge are as follows.
Since the bottom of the legal frame must be brought into close contact with the ground slope with an anchor and the ground must be tightened, the sediment discharge prevention sheet 1 is required to have a cross-sectional structure that does not impede such purpose, and also serves to prevent erosion within the legal frame. Because it requires a cross-sectional structure, it is thin, is well-suited to the ground, has good water permeability, and is composed of holes, meshes and thicknesses that do not allow sediment particles to flow out due to rain, etc., and is similar to hemp sheets etc. Any material can be used. If planting is necessary for the slope, the root hair of the plant is wrapped in close contact with the ground through the holes and meshes of the sediment runoff prevention sheet 1 or before the soil runoff prevention sheet 1 is laid on the cut slope. If the seeds 3 of the plant are sprayed, the buds grow from the holes of the sheet or the mesh 1a. In addition, in the snowy region, the greening that has propagated on the thick base material, etc., is often damaged by planting of the sloping area snow layer, but in the case of the present invention, in the sheet 1 for preventing sediment outflow under lath tension. Since the roots of the planted greenery remain entangled, the lath tension resists the snow in the snow layer, so there is little snow damage and breeding has been confirmed in the spring of the following year.

  In addition, the lath wire mesh can be seen to corrode and fall off over the course of a steep slope, so it should be a material that is resistant to corrosion to ensure the same service life as the legal framework. A mesh of synthetic resin may be used, and the mesh sizes 2a and 2b are set in consideration of the soil quality and slope of the site.

DESCRIPTION OF SYMBOLS 1 Sediment runoff prevention sheet, mesh fabric, hemp sheet 1a Sediment runoff prevention sheet 1 large mesh 1b Sediment runoff prevention sheet 1 small mesh 1H Sediment runoff prevention sheet 1 sheet thickness, mesh line Thickness 2 Lath wire mesh, synthetic resin mesh 2a Lath wire mesh horizontal mesh 2b Lath wire mesh vertical mesh 3 Plant seeds 4 Cut slope, ground slope 5 Anchor pin 6 Concrete frame, secondary product Pressure plate 6a horizontal space 6b vertical space H vertical frame height W horizontal frame width 7 reinforcing bar 8 anchor 9 mold 10 drilling hole 11 grout 12 anchor contraction device

Claims (4)

  In the construction of slope collapse prevention work by the anchor method frame construction method, laying a sediment prevention sheet on the cut slope, covering it with a lath wire mesh and fixing it with anchor pins, until the construction of the anchor method frame work is completed A ground slope erosion prevention method on the bottom of the frame, which is intended to prevent erosion of the cut slope during the period.   2. The method according to claim 1, wherein a hole and a mesh are provided on the surface of the earth and sand outflow prevention sheet so that the concrete mortar flows out and adheres to the ground slope when the concrete frame is cast in place and is integrated with the frame. Ground slope erosion prevention method at the bottom of the frame.   The bottom face of the frame according to any one of claims 1 and 2, wherein the size of the holes and meshes on the surface of the sediment discharge prevention sheet can be selected according to the size of the soil particles on the cut slope. Ground slope erosion prevention construction method.   The ground slope erosion prevention construction method of the bottom of the frame according to claim 1, wherein a sediment discharge prevention sheet is laid in the frame and in the frame to be used for the ground protection ground protection method.

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