Magnetic ring type testing device and method for foundation upheaval caused by foundation pit excavation

Abstract

The invention discloses a magnetic ring type testing device and method for foundation upheaval caused by foundation pit excavation. The magnetic ring type testing device comprises a protection steel pipe, PVC pipes, clamping rings, magnetic rings, a bolt, a reinforcing ring and a round pipe. The protection steel pipe is fixed to a concrete support through channel steel on a measuring platform, and when a foundation pit is excavated by a layer of soil each time, the protection steel pipe is welded to a steel support through the channel steel; the channel steel is constructed on the concrete support, a steel plate is welded to the channel steel, and a fence is installed on the peripheries of the constructed concrete support and the measuring platform, so that a testing pedestrian passageway and the measuring platform are formed; the PVC pipes are connected through pipe connectors; the multiple magnetic rings are arranged outside the PVC pipes in a sleeving mode, and the positions of the magnetic rings are controlled through the clamping rings or the PVC pipe connectors; only upper steel elastic pieces are installed on the magnetic rings; the round pipe is a force bearing point of a steel wire rope; and the PVC pipes are upwards pulled through the steel wire rope, so that the magnetic rings are separated from the clamping rings or the PVC pipe connectors, and upheaval testing is achieved. According to the magnetic ring type testing device and method for foundation upheaval caused by foundation pit excavation, the effect that the magnetic rings are accurately embedded in the design positions can be ensured; and foundation upheaval caused by foundation pit excavation is continuously monitored.

Description

technical field [0001] The invention relates to a device and a method for testing the uplift of foundation pit excavation, in particular to a magnetic ring type device and method for testing foundation uplift caused by foundation pit excavation. Background technique [0002] In foundation pit engineering, engineers are very concerned about the amount of foundation uplift caused by excavation. The size of the foundation uplift is mainly caused by the following factors: (1) the rebound deformation caused by the excavation and unloading of the soil; (2) the deformation of the foundation pit enclosure structure causes the extrusion of the foundation uplift; (3) the groundwater Uplift of soil due to buoyancy and seepage. Foundation uplift is an important basis for judging the stability and deformation of foundation pits, and it is also the main control index for the design and construction of foundation pits. [0003] At present, the method of testing the uplift of foundation p...

AI Technical Summary

Problems solved by technology

[0005] 1) The kraft paper rope is not easy to break when soaked in water. After 15 days of soaking in water for a kraft paper rope with a diameter of 1.8mm, the steel shrapnel of the magnetic ring has not bounced off, and the strength of the paper rope is still high, so the steel shrapnel cannot be used. role;

[0006] 3) Because the pipe is very long, the PVC pipe becomes a flexible pipe. When the PVC pipe is pressed down, the pipe, the magnetic ring and the soil contact and squeeze each other, resulting in greater resistance, causing the magnetic ring to slide to the inclinometer pipe joint or snap ring , or the paper rope is pulled off, causing the magnetic ring to slide to the inclinometer pipe joint or the steel shrapnel of the magnetic ring is crushed, so the uplift test cannot be realized or the role of the steel shrapnel cannot be played;

[0007] 3) When backfilling the gap, the melon seeds or sand are easily blocked by the magnetic ring, which cannot fill the gap by falling by its own weight, or drive the magnetic ring to move, causing the position of the magnetic ring to be far from the designed position;

[0008] 4) The backfill material has high water permeability. It is used in foundation pit excavation foundation uplift test, which will easily cause groundwater to rise along the hole, affecting the test accuracy. In severe cases, it will cause foundation pit safety accidents

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