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CN-121976574-A - Method for testing actual bearing load of existing engineering pile

CN121976574ACN 121976574 ACN121976574 ACN 121976574ACN-121976574-A

Abstract

The application provides a method for testing actual bearing load of an existing engineering pile, which comprises the steps of cutting a pile to be tested into an upper pile section and a lower pile section, enabling a foundation slab above the pile to be tested to generate sedimentation, obtaining the sinking height of a detection point on the foundation slab, installing a jacking device on the upper end face of the lower pile section, jacking the upper pile section, taking the jacking force of the jacking device as a measured value P of the actual bearing load of the pile to be tested before cutting when the foundation slab is lifted to the original position, continuously jacking and recording the load and sedimentation displacement of the pile section, drawing a load-sedimentation displacement curve of the lower pile section, obtaining the vertical ultimate bearing capacity N of the pile to be tested based on the load-sedimentation displacement curve of the lower pile section, and taking the arithmetic average value of the P and the N as a final report value of the actual bearing load of the pile to be tested. The application takes the average value of the measured value P and the vertical ultimate bearing capacity N as the final report value of the actual bearing load of the pile to be measured, thereby avoiding uncontrollable errors generated when indirect calculation is adopted.

Inventors

  • LI RENMIN
  • LIU XIAOBO

Assignees

  • 江苏东合南岩土科技股份有限公司

Dates

Publication Date
20260505
Application Date
20251226

Claims (6)

  1. 1. The load test method for the actual bearing load of the existing engineering pile is characterized by comprising the following steps of: (1) Cutting off a pile to be detected, enabling a foundation slab above the pile to be detected to generate subsidence, obtaining the subsidence height of a detection point on the foundation slab, and representing the subsidence height of the detection point by X, wherein the pile to be detected is cut off into an upper pile section and a lower pile section, the upper pile section is positioned above the lower pile section, a jacking space is formed between the upper pile section and the lower pile section, and the height of the jacking space is larger than X; (2) The method comprises the steps of installing a jacking device on the upper end face of a lower pile section, jacking the upper pile section, simultaneously settling the lower pile section in the jacking process, taking the jacking force of the jacking device as the load born by the lower pile section, recording the load and settlement displacement of the pile section, wherein the load is represented by Q, and the settlement displacement is represented by S; (3) Continuously jacking and recording Q and S, drawing a load-settlement displacement curve of the lower pile section, and rechecking the vertical ultimate bearing capacity of the pile to be laterally supported; (4) And taking the arithmetic average value of P and N as a final report value of the actual bearing load of the pile to be measured.
  2. 2. The test method according to claim 1, wherein in the step (1), before the pile to be tested is cut off, the measuring instrument is first installed above the test point, the test head of the measuring instrument is located right above the test point, then the initial position of the test point is measured, after the pile to be tested is cut off, the sinking position of the test point is measured after the foundation slab is settled and stabilized, and the difference between the sinking position and the initial position is the sinking height of the test point.
  3. 3. The test method according to claim 1, wherein before the pile to be tested is cut off, earth around the top of the pile to be tested is excavated first, an underground chamber is formed around the top of the pile to be tested, the cut-off position of the pile to be tested is located in the underground chamber, the pile to be tested is located in the central portion of the underground chamber, the underground chamber has an outlet, the distance between the outlet and the pile to be tested is 1-2m when the outlet is located outside a building or structure where the pile to be tested is located, and the distance between the outlet and the pile to be tested is 5-10m when the outlet is located inside the building or structure where the pile to be tested is located.
  4. 4. A test method according to claim 3, wherein the length of the underground chamber is 2-2.5m and the width of the underground chamber is 2-2.5m.
  5. 5. The method according to claim 1, wherein in the step (1), the pile to be tested is cut off by a static cutting method.
  6. 6. The test method according to claim 1, wherein before the upper pile section is lifted, leveling treatment is performed on a lower end face of the upper pile section and an upper end face of the lower pile section, so that the lower end face of the upper pile section forms a first leveling surface and the upper end face of the lower pile section forms a second leveling surface, and the lifting device is mounted on the second leveling surface.

Description

Method for testing actual bearing load of existing engineering pile Technical Field The invention belongs to the technical field of civil engineering detection and reinforcement, and particularly relates to a method for testing actual bearing load of an existing engineering pile. Background With the urban construction of China entering the stock age, a large number of existing buildings, bridges and other structures enter the maintenance and reinforcement period, the inclination of the building (structure) caused by the uneven settlement of the foundation is a common problem, and the pile-interception forced landing deviation correction is a widely applied deviation correction method. According to the deviation correcting method, part of engineering piles are cut off at the side with smaller sedimentation, loads are transferred to soil bodies and adjacent piles, controllable sedimentation is induced, and inclination is achieved. However, the process is not limited to the above-described process, The core bottleneck of this technology is that the actual load distribution of existing building pile foundations is unknown and highly non-uniform. This results in: the deviation rectifying efficiency is low, namely blind pile interception can only intercept a pile with smaller stress, the load transfer quantity is insufficient, the forced landing effect is poor, and the construction period is delayed. And if the key pile with larger stress is cut off, the load transient transfer of the key pile can cause overload damage of the adjacent pile, thereby causing foundation instability and even structural collapse. At present, an effective post detection means is lacking to measure the actual working load of the pile foundation: the traditional direct method (such as a reinforcing steel bar meter and a strain gauge) needs to be pre-buried in construction and is not applicable to the existing building. Indirect inferences (e.g. static load tests, high strain methods) are aimed at determining the ultimate bearing capacity (capacity properties) of a pile, not its current actual working load (state properties). This information cannot be used to evaluate the safety and efficiency of the stub. Numerical simulation, wherein the result is greatly influenced by model assumption, constitutive relation and parameter selection, and may have significant deviation with the pile foundation working state under actual complex working conditions. Therefore, there is an urgent need for a method of post, in-situ, direct, and reliable load testing of existing under-building single piles. Disclosure of Invention In order to solve the problems, the application provides a method for testing the actual bearing load of the existing engineering pile, which comprises the following steps: (1) Cutting off a pile to be detected, enabling a foundation slab above the pile to be detected to generate subsidence, obtaining the subsidence height of a detection point on the foundation slab, and representing the subsidence height of the detection point by X, wherein the pile to be detected is cut off into an upper pile section and a lower pile section, the upper pile section is positioned above the lower pile section, a jacking space is formed between the upper pile section and the lower pile section, and the height of the jacking space is larger than X; (2) The method comprises the steps of installing a jacking device on the upper end face of a lower pile section, jacking the upper pile section, simultaneously settling the lower pile section in the jacking process, taking the jacking force of the jacking device as the load born by the lower pile section, recording the load and settlement displacement of the pile section, wherein the load is represented by Q, and the settlement displacement is represented by S; (3) Continuously jacking and recording Q and S, drawing a load-settlement displacement curve of the lower pile section, and rechecking the vertical ultimate bearing capacity of the pile to be laterally supported; (4) And taking the arithmetic average value of P and N as a final report value of the actual bearing load of the pile to be measured. Before detecting the pile to be detected, firstly dividing the engineering pile on the side with smaller settlement of the inclined building or the structure into a plurality of pile groups, wherein each pile group comprises 4-12 engineering piles, randomly selecting one engineering pile from each pile group as the pile to be detected, and taking the detection data of the pile to be detected as the detection data of all the engineering piles in the pile group where the pile to be detected is positioned. The application takes the average value of the direct measurement value P and the vertical ultimate bearing capacity N of the pile to be measured as the final report value of the actual bearing load of the pile to be measured, thereby avoiding uncontrollable errors generated when indirect calculation is adopted