A test method for detecting the compressive bearing capacity of the grouting body at the end of a recoverable bolt

Abstract

The invention discloses a test method for detecting the compressive bearing capacity of a grouting body at the end of a recoverable anchor rod, comprising the following steps: S1. Install the tensionable and recoverable anchor rod top bars on the surface of the grouting body at the top of the recoverable anchor rod S2, start the jack to stretch the bar body, and use the load sensor and displacement meter to collect the tensile displacement and tensile load of the bar body respectively, and draw the tensile load-tensile displacement curve; S3, pass the tensile load - The tensile displacement curve determines the failure node where the grouting body under the bearing plate is damaged, and terminates the test loading after failure; the tensile load of the failure node is the ultimate load of the grouting body at the end of the recoverable anchor rod, and the ultimate load is divided by The compressive safety factor of the grouting body is the compressive bearing capacity of the grouting body; by placing the jack against the surface tensioning bar of the grouting body at the top of the recyclable bolt, the grouting body can achieve self-balance and avoid the grouting body being pulled out and damaged. , to ensure that the grouting body at the pressure-bearing plate is destroyed first, so as to achieve the purpose of testing the compressive bearing capacity of the grouting body on site.

Description

technical field [0001] The invention relates to the technical field of geotechnical anchoring engineering, in particular to a test method for detecting the compressive bearing capacity of a grouting body at the end of a recoverable bolt. Background technique [0002] With the rapid development of urban construction and traffic engineering construction, the use of traditional pile-anchor support in the deep foundation pits of urban construction will form super-long steel bars or steel strands in the stratum, which will give rise to subsequent engineering construction, especially subways. Shield construction caused serious obstacles. In order to solve this problem, the technology of recyclable bolts has been developed rapidly. The recyclable bolts belong to the pressure type bolts. The grouting body is squeezed by the bearing plate, and the pull-out resistance is further provided by the friction resistance between the grouting body and the rock-soil interface. The ultimate b...

AI Technical Summary

Problems solved by technology

The ultimate bearing capacity of the recoverable bolt mainly depends on the breaking force of the tendons, the frictional resistance of the interface between the grouting body and the rock-soil body, and the compressive bearing capacity of the grouting body at the bearing plate. The former two are relatively easy to control, while the latter is due to the Experience the constraints of the surrounding rock and soil, the constraints of the surrounding rock and soil will increase the compressive bearing capacity of the grouting body, so that the compressive bearing capacity of the grouting body at the bearing plate is actually higher than the compressive resistance of the grouting body itself The strength should be high, but at present, there is no reliable calculation method for how much the confinement effect of rock and soil has increased the compressive bearing capacity of the grouting body, so it is difficult to control the compressive bearing capacity of the grouting body at the bearing plate

Therefore, how to accurately detect the compressive bearing capacity of the recoverable anchor grouting body on the spot has become an urgent problem to be solved in testing the bearing capacity of the recoverable anchor rod. The most important thing is that the grouting body cannot be pulled out, which poses a great challenge to the field test of the compressive bearing capacity of the recyclable bolt grouting body

The existing method to solve the problem that the grouting body is easily pulled out during the test is to use a single super-long design drill hole to increase the frictional resistance of the grouting body, and then solve the problem of pulling out damage; but the above method cannot completely guarantee that the grouting body will not be pulled out In addition, the super-long design of the borehole also greatly increases the difficulty of construction, and the soil residue at the bottom of the borehole is not easy to clean, which affects the quality of the grouting body

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