Tension type prestress anchor rod for fixing soft rock stratum rock body and method

Abstract

The invention discloses a tension type prestress anchor rod for fixing a soft rock stratum rock body and a construction method. The tension type prestress anchor rod comprises an anchor rod hole and aprestress rib, the part, located in the hole, of the prestress rib is divided into an inner anchoring section with an inner anchor and a free section from inside to outside, the anchor rod hole, where the inner anchoring section is located, of the prestress rib is an inversed conical hole large in top and small in bottom, and the part among the prestress rib, the inner anchor and the hole wall ofthe inversed conical hole is filled with a grouting material; the height of the inversed conical hole of the inner anchoring section is 350-500 mm; the height of the free section prestress rib is 1-4m; the hole diameter of the part, where the free section is located, of the prestress rib is 55-65 mm; a device capable of stretching in the inversed conical hole in the radial direction and thus locating an isolation connector is arranged on the isolation connector. The adhering and anchoring strength among the inner anchoring section prestress rib, the condensed grouting material and the hole wall is high, the tension type prestress anchor rod is simple in structure, the material is saved, the construction is convenient, the vibration to the rock body layer in the construction process is small, and the anchor rod is applicable to an environment preventing a rock body rock from generating a collapse geological disaster along the layer.

Description

Technical field [0001] The invention relates to the technical field of geotechnical protection engineering, in particular to a tensile prestressed anchor rod and method for strengthening soft rock layered rock masses. Background technique [0002] In soft rock-like layered rock masses, especially those with thin to medium-thick layers such as 8-30 cm thick, there are many interbeds of rock fragments and muddy sand and cracks in the local bedding. With the development of cracks in rock-like bodies, geological disasters such as collapse and landslide may occur. [0003] In order to prevent the occurrence of landslide geological disasters, reinforcement treatment is required. The most commonly used and simpler structure and method is to use a tensile prestressed anchor rod reinforcement device. The treatment method is generally: first drill holes in the rock mass reinforcement area according to the design requirements of the spacing and depth, clear the holes, place pre-stressed tend...

AI Technical Summary

Problems solved by technology

However, in the rock mass where the horizontal rock layer is thin to medium thick, such as each layer of rock is 8-30cm thick, especially when the surface of the soft rock layered rock mass on the top of the grotto is severely weathered and the rock is prone to collapse along the layer During geological disasters, the tension type prestressed bolt reinforcement device and method of the above prior art are adopted to handle, but there are the following technical problems: 1, the structure of the anchorage section of the above prior art and the straight cylinder shape of the hole make the prestressed tendons The bonding performance between the solidified grouting material and the hole wall is not ideal, and the anchoring strength is not high

2. Due to the needs of anchoring section cohesive force and anchoring strength, the anchoring section of the above prior art is longer, and the grouting process is also inevitable for bedding penetration, so when the grouting material solidifies and shrinks between beddings, it will affect the Bedding produces new loosening, which is especially unfavorable for the reinforcement of collapse-type geological disasters

3. Due to the long length of the above-mentioned anchorage section, the pressure between the rock mass bedding is relatively concentrated, which has a negative impact on the local reinforcement effect

4. Due to the needs of the bonding force and anchoring strength of the anchoring section, the diameter of the drilling hole in the above prior art is generally between 110 and 150mm. Construction practice shows that the vibration during drilling operation will cause the bedding to loosen. The larger the diameter of the hole, the greater the impact of this vibration, the greater the possibility of bedding loosening during the operation, and the greater the negative impact on the safety of reinforcement and even construction operations

5. There is still a technical problem that has not been solved in the tension type prestressed anchor rod of the above prior art: the isolation joint between the inner anchorage section and the free section relies on hard plastic grouting pipes such as PVC grouting pipes for positioning, and the edge of the isolation joint and the hole wall The positioning and sealing effect is not ideal all the time. At the same time, if you want to pull out the hard plastic grouting pipe, you can only pull it out before the grouting material is solidified. However, if the hard plastic grouting pipe is not pulled out and remains in the bolt hole, the construction practice shows that it is difficult for the hard plastic grouting pipe to prevent the prestressed tendon and free section of the free section from being blocked. Interference between the casing of the section, which affects the tension effect of the free section of the prestressed tendon and the mechanical properties of the free section of the prestressed tendon

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