JPH0318555Y2 - - Google Patents

Description

[Detailed Description of the Invention] <<Industrial Application Field>> The present invention relates to a tensile reinforcing material used in rock anchor construction methods and underground anchor construction methods to prevent collapse and peeling of surrounding ground after tunnel excavation.

《Background of the idea》 During civil engineering works such as tunnel construction and dam construction, tensile reinforcing materials with axial tensile strength are inserted and buried along with self-hardening materials in the excavated areas in order to prevent the surrounding ground from collapsing or peeling. , construction methods that improve the physical properties of the ground have been adopted.

In these construction methods, rigid tensile reinforcing materials, such as steel bars, deformed steel bars, fiber-reinforced plastic rods, steel wires, etc., are generally used, such as lock bolts or anchor cables.

However, when these tensile reinforcement materials are cut and removed after the fact, they are difficult to cut with metal ones.
In addition, there is a risk of mechanical damage due to getting caught in the excavator, and it is necessary to bend the hole and insert it into the hole in a long hole where the hole is bent and displaced, or in an advanced tunnel with a small diameter. At times, it was difficult to insert rigid tensile reinforcement materials.

From these points, there has been a desire for a tensile reinforcing material that is non-metallic and has both flexibility and rigidity.

As a tensile reinforcing material basically having these characteristics, the present applicant has provided a lock bolt made by repurposing a fiber-reinforced thermosetting resin rope-like material (Japanese Utility Model Publication No. 56-48793).

However, when inserting a locking bolt using a rope-like material after injecting and filling the hole with a self-hardening material, which is the so-called pre-injection method, compressive force in the axial direction acts as the insertion progresses. The outer diameter of the rope-like object may expand due to the mutually independent strands bending outward, or the gap between the strands may become clogged with self-hardening material, causing the diameter to expand, making it impossible to insert the desired length. There were flaws.

In addition, if a locking bolt made of this rope-like material is inserted after injecting and filling mortar as a self-hardening material, the gaps between the strands will promote the filtration action, selectively separating and eliminating the cement milk, and the cement milk will be removed after hardening. There were problems such as concerns about retention.

Furthermore, even with the so-called post-injection method, in which self-hardening material is injected after inserting the lock bolt into the drilled hole, compressive force in the axial direction acts as insertion progresses, making insertion difficult due to diameter expansion. There was an inconvenience.

On the other hand, it is known that a fiber rope made of glass fiber is used as an anchor cable in the underground anchor construction method from the viewpoint of easy cutting. It is necessary to attach a weight to the end of the rope and use a guide rod to help with the weight, making it difficult to insert into bent or displaced holes or long holes.

<<Purpose of the invention>> The present invention was made in view of the above-mentioned problems, and is a novel tensile reinforcement method that solves the drawbacks of conventional lock bolts or anchor cables in the lock anchor method or underground anchor method. It provides materials.

<<Structure of the invention>> In order to achieve the above object, the present invention provides a tensile reinforcing material inserted into a ground borehole together with a self-hardening material for anchoring, the tensile reinforcing material being a reinforcement impregnated with an uncured thermosetting resin. After twisting or braiding composite strands coated with thermoplastic resin on the outer peripheral surface of the fiber bundle for use, the thermosetting resin is cured, and the thermoplastic resins of adjacent composite strands are bonded to each other. It consists of a rope-like structure that is fully fused and joined in the longitudinal direction at the contact part.

To explain in more detail, the fiber-reinforced thermosetting resin tensile reinforcing material uses uncured unsaturated polyester resin, epoxy resin, or other thermosetting resin, glass fiber, aromatic polyamide fiber, carbon fiber, Various polyethylene, ethylene-vinyl acetate copolymers, and various nylons are used as a core material impregnated with reinforcing fiber bundles such as polyester fibers and vinylon fibers that have high strength, low elongation, and strong retention properties and are shaped into a circular shape. , a thermoplastic resin such as various ABS is melt-extruded and coated in a ring shape, and then the coated portion is cooled to form an uncured composite strand, and this uncured composite strand is braided into a plurality of strands, for example, 8 strands. Then, a rope-like structure such as an eight rope (hereinafter referred to as eight rope) or a 1×7 type rope in which six strands are twisted around one composite strand around the outer circumference is formed, and then heated. It has a rope-like structure made of a fiber-reinforced thermosetting resin composite material in which the thermosetting resin of the core material is cured.

In particular, this tensile reinforcing material is characterized in that adjacent composite strands constituting a rope-like structure are fusion-bonded over the entire length in the longitudinal direction at their mutual contact points. The degree of bonding is important in order to keep the compressive elastic modulus and bending elastic modulus, which are physical properties related to ease of insertion into holes, into appropriate numerical ranges.

In other words, if we take a tensile reinforcement material as a lock bolt as an example, the drilled hole diameter is the lock bolt diameter D.
1.5 to 2D and using hardened mortar as a self-hardening material, which is a frequently used practical condition, the compressive elastic modulus is 150Kg/mm ² according to the measurement method described below.
Among the above values, when the bending elastic modulus is in the range of 15 to 100 Kg/mm ² , insertion work is easy and suitable.

When the compressive elastic modulus is 150 Kg/mm ² or less, the composite strand is deformed without resisting the axial compressive force during insertion, resulting in excessive insertion resistance.

On the other hand, when the bending modulus is 15Kg/ ^mm2 or less, the rigidity is low and the tip of the lock bolt bends due to its own weight during insertion, making it difficult to insert smoothly.
If it exceeds mm ² , its flexibility will be impaired and it will not be able to follow displacements such as bending of the drilled hole, making insertion work difficult.

In addition, whether the thermoplastic resin of the composite strand is bonded partially or completely in the longitudinal direction is determined depending on the physical properties required by the conditions of construction as a tensile reinforcing material. However, in the case of partial bonding, there is the problem of selective filtration and discharge of the cement milk when using mortar as the filling material, so we decided to bond the entire area.

Furthermore, as a joining method, it is preferable from an economic point of view to fuse thermoplastic resins together, and methods for realizing this include thermoplastic resins and thermosetting resins used for composite strands,
Then, by selecting the temperature conditions during heat curing, the heat generated during curing of the thermosetting resin during the curing process heats the thermoplastic resin on the outer periphery of the core material above its melting point, and the strands that come into contact weld together. Methods such as bonding are recommended.

More specifically, a composition that combines a resin with a relatively high curing exothermic temperature and a curing catalyst, such as an unsaturated polyester resin and a peroxide catalyst, is used as the thermosetting resin, and the coated thermoplastic resin is , resins with low melting or softening points, such as ethylene-
A composite strand is prepared using a vinyl acetate copolymer or the like, the composite strand is twisted or braided into a rope shape, and then the uncured rope shape is heated, for example, in a hot water bath. When the thermoplastic resin of the composite strand is heated above its melting point, the thermoplastic resin of the composite strand contacts continuously in the longitudinal direction and fuses with each other, while the thermoplastic resin of the outer periphery in contact with the hot water The temperature of the resin is radiated to this hot water, and the shape of the outer periphery is maintained.

That is, a rope-like structure is obtained in which the mutually contacting portions of adjacent composite strands are fused almost entirely in the longitudinal direction.

On the other hand, if a high-temperature heating medium is used under pressure as the heat curing condition, the above structure can be obtained even with a thermoplastic resin having a relatively high melting point.

In addition, the tensile strength of the tensile reinforcing material in the present invention varies depending on the value required based on the construction conditions, but it is generally a value of 5 tons or more, and the dimensions of the core material of the composite strand to obtain this strength are: For example, in the case of an eight-rope or 1x7 type rope, the reinforcing fiber bundle is glass roving, and the thermosetting resin is unsaturated polyester.The cross section is considered to be approximately circular, and the diameter is approximately 3.5 mm, and the outer circumference is approximately 3.5 mm. It is coated with thermoplastic resin about 0.5mm thick.

Furthermore, the twist length (lead) in a rope-like structure is related to the anchoring force as a tensile reinforcement material, that is, an anchor, but in this invention, the twist length (lead) is approximately 600
mm or less is preferable.

<<Embodiments>> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Example 1 For the core material 2 of the composite strand 1, glass fiber was used as the reinforcing fiber 3, unsaturated polyester resin was used as the thermosetting resin 4, and ethylene-vinyl acetate copolymer was used as the coating thermoplastic resin 5. are braided into an eight-rope shape and heated and hardened.
The volume content of glass fiber in the core material is 48%, the diameter of the core material having a roughly circular cross section is 5.4 mm, the outer diameter of the covering portion is 6.5 mm, and the covering resin of the eight composite strands is adjacent to each other. Each strand was almost fused to each other in the longitudinal direction to produce a tensile reinforcement material with dimensions of 24 mm at the maximum diameter and 16.3 mm at the minimum diameter.

The compressive elastic modulus and bending elastic modulus of this tensile reinforcing material, and the amount of displacement due to a cantilever beam as a measure of flexibility, were measured by the following measuring method.

In other words, the compressive elastic modulus is calculated by compressing a 300 mm long sample in the axial direction at a rate of 10 mm/min and applying a compressive load of -
A strain curve diagram was automatically recorded, and its tangential slope was determined to be the compressive elastic modulus. In addition, the bending elastic modulus is 150mm
Loading speed of 10mm/long sample with fulcrum distance of 100mm
A three-point bending test was conducted at 30 minutes, and measurements were made from the tangential slope of the load-strain curve in the same manner as described above.

Furthermore, as a measure of flexibility, as shown in Figure 6, the length of the chord is L when the tensile reinforcement is cantilevered with a beam length of 1000 mm and a load of 5 kg is applied to its free end.
mm was measured. It should be noted that the smaller the length of L, the more flexible it tends to be.

The tensile reinforcement material of this example obtained by these measurement methods had a compressive modulus of elasticity of 570 Kg/mm ² , a bending modulus of elasticity of 24 Kg/mm ² ,
The length of the string L = 840 mm, and the tensile strength was 13 tons.

Drill a hole with a diameter of 36 mm using this tensile reinforcement as a lock bolt.
After filling a drilled hole with a length of 4 m and a diameter of 4 m with hardened mortar, it was bent at an eccentric angle of 30° and fed, but the weight was approximately 65 kg.
Complete construction was possible with insertion resistance of .

Comparative Example 1 Compared to Example 1, low density polyethylene was used as the coating thermoplastic resin of the composite strand,
This covering part has an eight-rope structure having the same structure as in Example 1, except that it is not fused to each other in the length direction, and has a compressive elastic modulus of 35 Kg/mm ² .
A tensile reinforcement material with a bending modulus of elasticity of 11 Kg/mm ² and a string length of 720 mm was obtained.

When this tensile reinforcement was used as a lock bolt and insertion work was attempted under the same conditions as in Example 1, the result was 1.3
I could only insert m.

Example 2 A composite strand with the same configuration as Example 1, the outer diameter of the core material was 6.3 mm, the outer diameter of the coating was 7.5 mm, the volume content of glass fiber was 48%, and the thermoplastic resin of the composite strand was When the 1 ^× 7 ^type rope structure was fused almost entirely over
A tensile reinforcement material with a diameter of 920 mm and a tensile strength of 13.8 tons was obtained.

When this reinforcing material was tried to be used as a lock bolt under the same conditions as in Example 1, the eccentric angle
It was possible to insert 4 m at 30° and insertion resistance of 65 kg.

Comparative Example 2 A 1×7 type rope-like structure was used with exactly the same size and shape except that low-density polyethylene was used instead of the coating thermoplastic resin used in Example 2, and the composite strand was made into a 1×7 type rope-like structure, with the exception that low-density polyethylene was used instead of the coating thermoplastic resin used in Example 2. A non-fused one was obtained. However, since this product has a structure in which the composite strands are simply twisted together, the strands become loose due to the feeding roller used for insertion work, making it unusable.

<<Effects of the invention>> As explained in detail above, by using the tensile reinforcing material according to the invention, complete insertion work can be performed with a relatively small force up to an eccentric angle of about 30° from the drilling axis. In addition, the anchor anchoring force as a tensile reinforcing material has at least an effective anchoring force due to the unevenness of the composite strand that constitutes the rope-like structure.
Furthermore, the self-hardening material to be filled in the hole, the thermoplastic resin of the composite strand, and the combination of the thermoplastic resin and thermosetting resin are selected based on whether these resins have mutual chemical affinity or solubility factors. If similar ones are selected, fixation can be achieved by the adhesive force between them, and the efficiency of tensile reinforcement can be improved.

In addition, when the composite strand is non-adhesive in a structure such as a 1×7 type rope, Comparative Example 2
As described above, the strands are separated and cannot be used in practical use, but by fusion bonding, complete insertion into the drilled hole becomes possible as described in Example 2.

This has the potential to be economically produced with relatively simple twisting equipment.

Furthermore, since the tensile reinforcing material of the present invention is made of a fiber-reinforced thermosetting resin composite, it has both compressive elasticity and bending elasticity, and has high tensile strength comparable to that of iron. Therefore, it is easy to insert eccentrically at the hole opening, it has the ability to follow the bending of the hole itself, and it can be endlessly wound into a drum shape and supplied, so it can be cut to any length. that it is possible,
It can bring about a number of effects, such as being lightweight and easy to handle, being corrosion resistant, and making it easy to cut buried objects during post-construction work.

These numerous effects of the present invention are particularly useful in tunnel excavation, when the properties of the ground are poor and the stress release after excavation is large and there is a fear of collapse.
As a tensile reinforcing material when an advanced tunnel with a small cross section is dug prior to excavation of the main tunnel, then relatively long lock bolts are driven to reinforce the ground, and the lock bolts are cut during the next cutting and expansion. , the effect is particularly pronounced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the structure of a composite strand of a tensile reinforcing material of the present invention, FIG. 2 is a side view showing a tensile reinforcing material as an example of the present invention corresponding to Example 1, and FIG. 4 and 5 are cross-sectional views of FIGS. 2 and 3, respectively, and FIG. 6 is a schematic diagram of a method for measuring physical properties as a measure of flexibility. 1... Composite strand, 2... Core material, 3... Reinforcing fiber, 4... Thermosetting resin, 5... Thermoplastic resin.

Claims (1)

[Scope of utility model registration request] In a tensile reinforcing material inserted into a hole in the ground along with a self-hardening material for anchoring, the outer peripheral surface of the reinforcing fiber bundle impregnated with an uncured thermosetting resin as the tensile reinforcing material is coated with a thermoplastic resin. After the coated composite strands are twisted or braided, the thermosetting resin is cured, and the thermoplastic resins of the adjacent composite strands are completely bonded in the longitudinal direction at their mutual contact areas. A tensile reinforcing material inserted into a ground borehole, characterized by comprising a fusion-bonded rope-like structure.