Method for measuring pile shaft internal force and cross section displacement in vertical dead-load test of foundation pile

Abstract

The invention belongs to the technical field of pile foundation quality detection in civil engineering, in particular to a method for measuring pile shaft internal force and cross section displacementin vertical dead-load test of a foundation pile. In the method, firstly, a casing is embedded on a pile shaft lengthways or holes are directly drilled on the pile shaft lengthways; a measuring systemis arranged in the casing or the drilling hole and is composed of an anchor head, a multiple position extensometer, an extension bar and a pressure pipe, wherein, the pressure pipe pressurizes to expand the anchor head so as to ensure that the anchor head is fixed in the casing or the drilling hole; after the anchor head is fixed, the multiple position extensometer measures vertical deformation between two adjacent anchor heads by the extension bar; according to a vertical displacement observation result and vertical deformation between two adjacent anchor heads, the layering frictional resistance of each soil layer, pile end supporting force and the vertical displacement of anchor head embedding cross section are calculated, and the relation of pile soil relative displacement and pile side frictional resistance is built so as to realize pile shaft internal force and cross section vertical displacement measurement. The invention has high test accuracy and favorable reliability, can replace traditional method using strain or string-wire sensors and displacement rods to measure pile shaft internal force and cross section vertical displacement.

Description

technical field [0001] The invention relates to a method for measuring the internal force of a pile body and the displacement of a section in a vertical static load test of foundation piles, and belongs to the technical field of pile foundation quality detection in civil engineering. Background technique [0002] In the quality inspection of pile foundation engineering, the static load test method is often used to detect the vertical bearing capacity of the foundation piles in the pile foundation. In the traditional internal force and section displacement test of the vertical pile body of foundation piles, the method of embedding strain sensors and connecting wires and casings during pile making is generally used, and the following problems arise: [0003] (1) On the one hand, the workload of embedding strain gauge or steel string sensors and displacement rods is very large and extremely cumbersome. On the other hand, the high temperature during sensor welding, concrete pour...

AI Technical Summary

Problems solved by technology

[0003] (1) On the one hand, the workload of embedding strain gauge or steel string sensors and displacement rods is very large and extremely cumbersome. On the other hand, the high temperature during sensor welding, concrete pouring and vibration, and heat of hydration generated during concrete curing Many complex factors, such as the sensor, will cause serious damage to the sensor, connecting wires, etc., which will lead to the inability to collect complete data or even completely fail to conduct the test.

[0004] (2) On the one hand, the intervention of the sensor makes the strain at the buried point produce stress distortion, and the strain value measured by the sensor deviates from the true value; on the other hand, the strain value detected by the sensor only represents the strain at the buried point. The strain distribution of

[0005] (3) Once the construction is fixed, the buried position cannot be adjusted, and the sensor cannot be replaced. Even if the buried position is found to be wrong, or even the sensor and the connecting cable are damaged, it is difficult to take remedial measures

[0006] (4) Shaking and friction between the inner and outer tubes of the displacement rod can easily cause data errors

At the same time, after deducting the area occupied by the jack from the cross-sectional size of the pile top, the number of buried displacement rods is strictly limited

[0007] (5) Sensors, connecting cables and displacement rods cannot be recycled, cannot be reused, and are not economical

Images