After processing, the pile defects and their locations are given, Determine the pile integrity category.
Pile integrity is classified into four categories: Class I pile, Class II pile, Class III pile and Class IV pile.
Through measuring the pile top settlement of a single pile under different loads, the Q-s curve and s-lgt and other auxiliary curves of the static load test are obtained, and then the characteristic values of the vertical compressive bearing capacity of a single pile and other parameters are calculated according to the curve.
Determination of the characteristic value of the horizontal bearing capacity of a single pile: First, when the pile body is not allowed to crack or the reinforcement ratio of the cast-in-place pile is less than 0.65%, 0.75 times of the horizontal critical load is taken; Second, for reinforced concrete precast piles, steel piles and cast-in-place piles with a reinforcement ratio of no less than 0.65%, 0.75 times the load corresponding to the horizontal displacement at the design pile top elevation shall be taken (horizontal displacement value: 6mm for buildings sensitive to horizontal displacement, 10mm for buildings insensitive to horizontal displacement, meeting the requirements of pile crack resistance).
Aim To determine the horizontal critical and ultimate bearing capacity of single pile, and to estimate the soil resistance parameters; Determine whether the horizontal bearing capacity or horizontal displacement meet the design requirements; The bending moment of the pile is measured through the pile strain and displacement tests.
When the core drilling method is selected, the requirements for the number and location of boreholes for each pile to be tested: 1~2 boreholes can be used for piles with a pile diameter less than 1.2m; The pile with a pile diameter of 1.2~1.6m should have 2 holes; The pile with a pile diameter greater than 1.6m should have 3 holes; The drilling position should be evenly and symmetrically arranged within the range of (0.15~0.25) D from the pile center..
Single pile vertical static load test refers to transferring the vertical load evenly to the building foundation pile.
During acceptance inspection, it is advisable to inspect the integrity of the pile body first, and then the bearing capacity.
Objective To detect the defect and position of cast-in-place pile body, and determine the type of pile integrity.
Aim To determine the vertical compressive ultimate bearing capacity of single pile; Determine whether the vertical compressive bearing capacity meets the design requirements; Through the pile body strain and displacement tests, the pile side and pile end resistance are measured to verify the test results of the vertical compressive bearing capacity of a single pile using the high strain method.
Aim to determine whether the vertical compressive bearing capacity of single pile meets the design requirements; Detect the pile defects and their positions, and determine the pile integrity category; Analyze the soil resistance of pile side and pile end; Monitoring the piling process.
Aim To determine the ultimate vertical uplift bearing capacity of single pile; Judge whether the vertical uplift bearing capacity meets the design requirements; The uplift resistance of the pile is measured through the pile body strain and displacement tests.
Single pile vertical compressive static load test.
The characteristic value of vertical uplift bearing capacity of single pile shall be taken as 50% of the ultimate vertical uplift bearing capacity of single pile.
6 High strain method High strain detection method is a method to detect the integrity of the pile shaft of the pile foundation and the vertical bearing capacity of a single pile.
The single pile horizontal load test should adopt the one-way multi cycle loading and unloading test method, and when it is necessary to measure the stress or strain of the pile body, the slow maintenance load method should be adopted.
7 Acoustic transmission method The acoustic transmission method is to embed several acoustic pipes in the pile before pouring the pile foundation concrete as the channel of the ultrasonic pulse transmitting and receiving probe, measure the acoustic parameters when the ultrasonic pulse passes through each cross section point by point along the longitudinal axis direction of the pile with an ultrasonic detector, and then use various specific numerical criteria or visual judgments for these measured values.
The specified procedure is used to analyze and calculate, so as to obtain the integrity parameters of the pile shaft and the vertical bearing capacity of a single pile, also known as Case method or Cap wape method.
The pile integrity test shall be carried out after the excavation of the foundation pit.
Aim To detect the pile defects and their positions, and determine the pile integrity category.
This method uses a heavy hammer with a hammer weight of more than 10% of the pile weight or more than 1% of the vertical bearing capacity of a single pile to hit the pile top in a free fall, so as to obtain the relevant dynamic coefficient.
3 The horizontal static load test of single pile adopts the test method of determining the horizontal bearing capacity of single pile and the horizontal resistance coefficient of foundation soil by approaching the actual working conditions of horizontally stressed piles, or checking and evaluating the horizontal bearing capacity of engineering piles.
Class I pile body is complete; Class II pile body has slight defects, which will not affect the normal play of the bearing capacity of the pile body structure; Class III pile body has obvious defects, which affect the bearing capacity of pile body structure; Class IV pile body has serious defects.
1.
According to the core samples taken, the length of the pile foundation, the concrete strength, the thickness of the sediment at the bottom of the pile, and the condition of the bearing stratum can be clearly judged.
The characteristic value of vertical compressive bearing capacity of single pile shall be taken as 50% of the vertical compressive ultimate bearing capacity of single pile.
2.
Key points for the implementation of pile foundation inspection Selection conditions for the inspected piles for acceptance inspection: (1) The piles with construction quality in doubt; (2) Piles with abnormal local foundation conditions; (3) Select some Class III piles for bearing capacity acceptance; (4) Piles considered important by the designer; (5) Piles with different construction technologies; (6) It should be selected uniformly and randomly as specified.
Source: network, 7 methods of pile foundation detection are introduced and deleted.
The purpose is to measure and inspect the pile length, concrete strength of pile shaft, and sediment thickness at the bottom of pile, judge or identify the geotechnical properties of pile end bearing stratum, and determine the type of pile integrity.
The vertical uplift static load test of single pile applies the vertical uplift force on the top of the pile step by step, and observes the uplift displacement of the top of the pile over time to determine the corresponding test method of the vertical uplift bearing capacity of single pile.
4 Core drilling method The core drilling method mainly uses a drilling machine (generally with an inner diameter of 10mm) to take core samples for the pile foundation.
5 Low strain method Low strain detection method is to use a small hammer to knock the pile top, receive the stress wave signal from the pile through the sensor bonded to the pile top, study the dynamic response of the pile soil system using the stress wave theory, back analyze the measured speed signal and frequency signal, and obtain the integrity of the pile.
