JPS63156120A - Construction for cast-in-place form of slope - Google Patents

Abstract

PURPOSE:To increase the load of an anchor, by making the width and thickness of an anchor-casting section larger than those of other sections, for construction of the form of slope. CONSTITUTION:Forms 4 are arranged on the face R of slope and are assembled in the shape of parallel crosses, so that the thickness H of an anchor-casting section 2 is larger than that h of other sections 1a, 1b. After that, at the central position of the casting section 2, a reinforcing pipe 5 is set; mortar 6 is cast in the forms 4 by a spraying method. Then, an anchor pit is board through to a deep section of the surface of sliding, and an anchor steel rod 3a is inserted into the pit and is fixed by injecting cement milk at the anchorage section. As a result, anchor yield strength can be economically obtained, and the applica tion range can be widened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cast-in-place frame construction method for protecting slopes that are at risk of collapsing or collapsing, such as cut earth surfaces and embankment slopes.

[Conventional technology]

Cast-in-place frame construction methods (free frame construction method, strong frame construction method) have been adopted in recent years for various disaster prevention construction works.
There is a tendency towards diversification. The prevention works that are mainly adopted are:
These include collapse prevention work on steep slopes, landslide work, slope protection work for new roads and dam structures, etc. In these works, the use of anchor force as a deterrent is increasing.

Generally, the strength of concrete used in civil engineering works is based on the concrete standard specification adopted by the Japan Society of Civil Engineers in 1981, but the cast-in-place frame method (the frame method for mortar and concrete spraying) is also considered to be equivalent, and its design In this regard, the allowable stress level shown in the above-mentioned concrete standard specifications is often adopted.

[Problem that the invention seeks to solve]

Demand for this type of construction method is expected to increase in the future.

However, with this revision, the design standard strength of special cast-in-place frame construction methods (free frame construction method, strong frame construction method) is expected to be significantly reduced as shown in Table 1 below.

Calculating the anchor load that can be introduced based on the allowable stress levels in Table 1 above, the maximum 2
Approximately 0 ton, 15 ton when considering shear stress
It decreases to about on level. Since this value is considerably lower than conventional methods, the advantage of combining it with this construction method will be diminished, and if it continues as it is,
The scope of construction may be limited.

Therefore, the main purpose of the present invention is to provide an economically viable and
The objective is to provide a cast-in-place frame construction method that can increase the anchor load.

[Means for solving problems]

In order to achieve the above-mentioned object, the present invention constructs the above-mentioned slope frame using the cast-in-place method of constructing the slope frame on the slope ground using the spraying method and driving anchors at appropriate locations on the slope. In this case, at least the width and thickness of the anchor driving part is made thicker than other parts.

Various forms of slope frames are selected depending on the situation of the slope, and they are constructed by cutting grooves in the slope, or by arranging and assembling certain wart forms and spraying mortar or concrete into the grooves or formwork.

For example, when a landslide is expected, the legal frame may be a parallel girder or diagonal lattice, and when the collapse is only localized, only vertical frames or only horizontal frames may be used.

When assembling the slope into a parallel girder or diagonal lattice, select the intersection of the two as the anchor placement area.If there are only vertical or horizontal frames, consider the slope condition and form the anchor placement area at the appropriate location. do.

Conventionally, the thickness and width of the anchor driving part were formed to be the same as other parts, but in the present invention, the thickness and width of the anchor driving part are formed to be thicker than other parts, so that the strength of the legal frame and the anchor is improved. .

In addition, if necessary, reinforcing bars or prestressed steel strands may be laid in the groove or formwork to improve the strength of the framework, and the width of the anchoring part may be widened to reduce the support surface pressure. It's okay.

[For production]

When anchors are installed and tensioned, each beam of the slope receives a distributed or concentrated load as a reaction from the slope, and a bending moment is generated in each beam of the slope. This bending moment is greatest immediately below the anchor driving point, and this bending moment generates a tensile force on the back surface of the anchor driving part, but in the present invention, the thickness of the anchor driving part is formed thicker than other parts. Therefore, the section modulus of that part is large, and the tensile stress generated on the back surface is small. Therefore, the strength of the anchor can be increased and the range of application can be further expanded.

〔Example〕

Examples will be described below with reference to the drawings.

In the present invention, various forms of the slope frame and the anchor driving portion can be adopted depending on the situation of the slope.

In the example shown in Fig. 1, the slope frame 1 is assembled into a parallel girder, and the beams la, lb
The tolerance part is set as the anchor driving part 2, and is applied to slopes where landslides are expected.

In the illustrated example, the width of the anchor driving part 2 is larger than the width of the beams 1a and 1b to widen the support surface, and the thickness H is thicker than the thickness h of the other parts 1a and lb, that is, the width of the anchor driving part 2 is larger than that of the beams 1a and 1b. , lb. are built deeper and thicker.

In addition, in the illustrated example, the formwork 4 is formed of wire mesh and filled in when constructing the legal frame 1, but the formwork 4 is not limited to this, and the formwork 4 is made of water-resistant cardboard, expanded metal , synthetic resin foam, concrete plate, etc. As can be seen in the figure, within the formwork 4, reinforcing bars or PC steel stranded wires 4a,... are arranged on the top, bottom, left and right as needed, and the tensile force generated in the longitudinal direction is transferred to these reinforcing bars or PC steel stranded wires. 4a, . . . may share the role of Uke. Further, in constructing the legal frame 1, it is desirable to bury a reinforcing pipe 5 at the center of the anchor driving portion 2 as a guide for the anchor steel rod 3a.

The construction can be carried out in the following order, for example.

(1) First, the formwork 4 made of wire mesh is placed on the slope R, and assembled into a cross section, and the intersection is made so that the thickness H of the anchor driving part 2 is thicker than the thickness h of the other parts 1a and lb. Dig into a rectangular shape directly below to form the anchor driving part 2.

(2) If necessary, use auxiliary anchors to fix the formwork 4 on the slope R, and then install reinforcing bars or PC in the formwork 4.
Steel stranded wires 4a are arranged vertically and horizontally.

(3) Once the anchor installation part 2 is assembled in this way, the reinforcing pipe 5 is arranged at its center position, and then mortar or concrete 6 is poured into the formwork 4 using the spraying method. Reinforcement or PC when pouring! ijl strand 4 a
A high-frequency vibro may be attached to +..., and the placed mortar or concrete 6 may be uniformly compacted by the vibration of the vibro.

(4) In the anchor placement part 2, a large amount of mortar or concrete 6 is sprayed, and then the shape is shaped into the prismatic shape shown in FIG. 1 by hand or by a component. The other portions 1a and lb may also be shaped by similar means.

(5) After completing the construction of the legal frame 1 as described above, cast the anchor.

(6) First, drill an anchor hole through the reinforcing pipe 5 until it reaches the deep part of the sliding surface, then insert the anchor steel rod 3a into the hole, and inject cement milk or mortar into the anchoring part to fix it. do. After a curing period of about 4 weeks, the anchor head is tightened to the anchor driving part 2 with a washer 3b and a pad 3C, and the anchor steel rod 3a is fixed under tension.

Next, to protect the anchor head, the head is buried in mortar or concrete.

The above is an example of making the anchor driving part deeper and thicker than other parts, but if the slope is hard like rock, anchor driving should be done as shown by arrow A in Figure 2. It is also possible to make the height of the installation part 2 higher than the height of the other parts 1a and lb, and to make it thicker.

Moreover, as shown in arrow B, both may be used together.

Although the above embodiment is an example in which the thickness of the anchor driving portion is made discontinuously larger than the thickness of the beam, it may be made continuous as shown in FIG. In this example, each beam 1a constituting the parallel
, lb are increased asymptotically, and the thickness of the anchor driving part 2 is finally made thicker than the other parts 1a and lb. In this example, the anchor installation part 2 and the beams 1a, l
It is difficult for stress concentration to occur between the beams 1a and 1b.
Since the cross-sectional area of the material increases as the bending moment increases, it exhibits strong resistance to bending.

In Fig. 4, in order to have equal strength in the radial direction, the shape of the anchor driving part 2 is cylindrical, and the other parts 1a,
This is an example where it is higher than lb. In this example, as shown in FIGS. 5 and 6, the spiral reinforcement 7 is arranged concentrically with the reinforcing tube 5 to prevent splitting and the like.

In construction, the first thing to do is to build the beam 1a that will make up the crossbeam.

1b and the intersection thereof, a formwork is placed along the broken line shown in FIG. After placing the beams 1a and 1b, reinforcing bars or PC steel wires 4a, etc. are placed above and below, on the left and right sides of the beams 1a and 1b to form a framework.

The material constituting the formwork may be water-resistant cardboard, synthetic resin foam, concrete board, wooden mold, or the like. In the embodiment, the height of the anchor driving part 2 is different from that of the other parts 1a and lb.
Since it is higher than the other parts, it is desirable that the formwork is also higher than the other parts.

Next, mortar or concrete 6 is sprayed from above toward the formwork to construct the legal frame 1. After leveling the upper surface of the legal frame 1 with a trowel or the like, anchors are driven. Since the anchor placement is the same as in the previous embodiment, the explanation thereof will be omitted here.

7 and 8 are examples applied when the condition of the slope R is only a local collapse. In this example, the slope frame 1 is composed of only vertical frames, and anchors are placed at appropriate locations. Casting part 2
is provided. Vertical frame 1. 1 and 1, there is a gold WI8 covering the slope R, and a plurality of reinforcing bars or PC steel stranded wires 9 placed laterally to press down the wire mesh 8. ... provides a deterrent effect. The anchor driving portion 2 may be formed into a square column as shown in FIG. 7, or may be formed into an elliptical column as shown in FIG. In either case, it is formed higher than other parts.

The construction can be carried out in the following order, for example.

(1) First, there is gold along the slope R that requires deterrence! ii
8, and then reinforcing bars or PC steel stranded wires 9,...
・Crawl horizontally. Rebar or PC used here
Steel strand9. ... is exposed to rainwater, so if possible, it is desirable to have a sheath to prevent corrosion.
・(2) Next, a formwork 4.4 made of wire mesh is placed at a predetermined position in the vertical direction of the slope R, and reinforcing bars or PC steel stranded wires 6 are placed along the formwork.
．． ... will be installed. Although not shown, a reinforcing tube that serves as a guide for the anchor 3 is previously installed upright at a position that will become the anchor installation portion 2 .

(3) Once the framework is assembled in this way, mortar or concrete 6 is sprayed into the formwork 4.4 to construct the legal framework 1.

(4) Level the top and side surfaces of the legal frame 1 using a trowel or the like, especially in the anchor driving part 2, so that it becomes a square column as shown in Fig. 7 or an elliptical column as shown in Fig. 8. Adjust the shape.

(5) Next, wait for the strength of the mortar or concrete to develop, and then cast the anchor 3. This casting is carried out in the same manner as in the previous embodiment.

The slope 1 is constructed using the above procedure to protect the slope that is at risk of collapse.

〔Effect of the invention〕

Even if an allowable stress level lower than the conventional method is newly set, according to the method of the present invention, it is possible to economically obtain an anchor proof strength comparable to that of the conventional method, and the range of application can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing one embodiment of the present invention, FIG. 2 is a perspective view showing a modification of FIG. 1, and FIGS. 3 and 4 show other embodiments of the invention. FIG. 5 is a plan view showing the framework of FIG. 4, FIG. 6 is a front view of FIG. 5, and FIGS. 7 and 8 are longitudinal views showing the specific structure of the present invention. FIG. 4 is a perspective view suitable for frames only; 1... Law frame, la, lb... beam, 2... anchor driving part, 3... anchor, 3a... anchor steel bar,
3b...Washer, 3C...Nand, 4...Formwork, 4
a...Reinforcing steel or PC! ! 4 stranded wire, 5... reinforcing pipe,
6...Mortar or concrete, 7...Spiral reinforcement, 8...Wire mesh, 9...Reinforcement bar or PC steel stranded wire,
R...Slope surface, H...Thickness of anchor installation part, h...
・Thickness of the beam (other parts). Patent applicant: Light Kogyo Co., Ltd. Representative: Yoshihisa Nagai, patent attorney Figure 1 Figure 2 Figure 4 Figure 5 Figure 7 Figure 8

Claims (1)

[Claims] (1) In the cast-in-place method, in which a slope is constructed using the spraying method on top of the slope and anchors are driven at appropriate locations on the slope, when constructing the slope, it is necessary to A cast-in-place frame construction method characterized by making at least the width and thickness thicker than other parts.