CN1164643A - Low-strain transient admittance state regulation factor method for detecting bearing capacity of foundation pile - Google Patents
Low-strain transient admittance state regulation factor method for detecting bearing capacity of foundation pile Download PDFInfo
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- CN1164643A CN1164643A CN 97104326 CN97104326A CN1164643A CN 1164643 A CN1164643 A CN 1164643A CN 97104326 CN97104326 CN 97104326 CN 97104326 A CN97104326 A CN 97104326A CN 1164643 A CN1164643 A CN 1164643A
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Abstract
The low-strain transient admittance state ajustment factor method for detecting bearing capacity of foundation pile belongs to the field of nondestructive detection. According to the measured speed admittance value and response frequency value on the transient admittance curve of foundation pile, said invention uses low-frequency broad pulse force rod or force rammer shock to solve for tested bearing capacity Qd, and then according to the tested value, the state adjustment factor nQ corresponding to the tested value can be sought out on the state ajustment factor curve, and the tested value can be corrected, so that the bearing capacity of said foundation pile can be obtained. Said invented equipment is portable, detection process is simple and quick, detection result is accurate, and cost is low.
Description
The invention belongs to the Non-Destructive Testing category, is the low-strain transient admittance state regulation factor method that is used to detect pile bearing capacity.
Traditional pile bearing capacity detection method is to adopt Static Load Test Method.Just, be loaded on the load of regulation gradually at the foundation pile top, whether reach designing requirement with the check pile bearing capacity according to the bearing capacity of design code.This method is directly perceived, is easy to be accepted by people, is the basic skills of the detection pile bearing capacity of present home and abroad standard defined.But because the used checkout equipment heaviness of this method, speed is slow, the expense height, thereby the quantity of detection foundation pile can not be many, be difficult to the total quality of pile foundation engineering is made evaluation, and the static load peg, because to certain requirement is arranged by peg, as needing anchoring pile around it, pile crown needs reinforcement etc., in most of the cases, can not carry out random sampling to foundation pile and detect, can only carry out for detecting on the foundation pile of doing special.
Dynamic measurement of pile detects foundation pile has easy, quick, advanced technology, advantage that expense is low than Static Load Test Method.The high strain dynamic test method is carried out exciting to the survey foundation pile when detecting, require tested foundation pile that certain pile penetration is arranged, generally should be less than 2 millimeters, and this method relatively is applicable to driven pile, can detect by means of ram engine.But for bored concrete pile difficulty relatively then, it need dispose heavy hammering equipment (hammer heavily for estimate bearing capacity 1%); Higher to the pile crown processing requirements, the repairing of pile crown, tear open all take a lot of work, time-consuming, effort, particularly to the detection of bridge foundation pile difficulty more just.This method is because performance difficulty is also impossible high to the sampling observation rate of foundation pile.
Method such as available dynamic parametric method, transient state mechanical impedance method, stable state mechanical impedance method, resonant method, hydroelectric effect method and the present invention belong to low deformation dynamic inspection method together, but, the excitational equipment of these methods is complicated heavy, use trouble, the dynamic and static testing comparison correction all is to adopt artificial within the specific limits experience value.
The objective of the invention is to overcome the shortcoming that above-mentioned prior art exists, a kind of cumbersome apparatus that do not need is provided, be suitable for on-the-spot easy, quick, the advanced technology of using, do not disturb construction, testing result is not influenced by subjective factor, can improve the method for foundation pile sampling observation rate and the detection pile bearing capacity that carries out the foundation pile generaI investigation as requested.
The object of the present invention is achieved like this: adopt low frequency broad pulse power rod (or power rammer), carry out the transient impact exciting at the foundation pile top, its transient impact power is recorded by the force cell on the power rod (power rammer), and dynamic response is received by the sensor that is installed in the foundation pile top; Transient force signal and dynamic response signal are simultaneously by the collector collection, and through Computer Processing, draught machine (or printer) is drawn the transient admittance curve of reflection pile-soil system dynamic characteristic.On this curve low-frequency range, get a little, obtain the test value Qd of pile bearing capacity, adjust curve according to this test value Qd by state and find state adjustment coefficient η
Q, adjust coefficient η with this state
QQd revises to test value, can obtain this pile bearing capacity Qa.
The present invention has following advantage compared with the prior art:
1. with traditional Static Load Test Method comparison, it has, and checkout equipment is light, and testing process simply, fast, is not disturbed construction, and testing cost is low, sampling observation rate advantages of higher.
2. compare with other dynamic measurement of pile, following advantage then arranged:
1. power rod (power rammer) exciting, equipment is simple, and is easy to use.
2. the employing state is adjusted the coefficient correction, when having avoided selected by rule of thumb modified value subjective random, scientific and reasonable, be easy to grasp.
3. trace routine is easy, quick, the testing result good reproducibility.
4. measuring accuracy height, coherence function is greater than 0.9.
Fig. 1 is a transient admittance state regulation factor method detection system;
1-power rod among the figure, 2-foundation pile, 3-force cell, 4-sensor, 5-amplifilter, 6-collector, 7-computing machine, 8-draught machine;
Fig. 2 is the transient admittance curve map;
Fig. 3 adjusts coefficient curve figure for state.
Now further specify the present invention in conjunction with the accompanying drawings and embodiments.
Present embodiment adopts in pulse width 5～20ms scope, the low frequency broad pulse power rod 1 (patent No.: 90201298.3) of frequency 10Hz～300Hz, carry out the transient impact exciting at foundation pile 2 tops, its transient impact power is recorded by the force cell on the power rod 13, dynamic response is received by the sensor 4 that is installed in foundation pile 2 tops, transient force signal and dynamic response signal are gathered by collector 6 later on simultaneously by amplifilter 5, deliver to computing machine 7 again, calculate sequential operation by commercially available computing machine FFT (fast Fourier transformation) transport function and obtain the V/F-f mechanical admittance curves.Result of calculation is exported by draught machine 8, thereby obtains reflecting the mechanical admittance curves 9 (accompanying drawing 2) of this pile-soil system dynamic characteristic.The ordinate of this curve is the velocity admittance value---the ratio (V/F) of response speed V and transient impact power F, and horizontal ordinate is represented corresponding frequencies f, and the low-frequency range of this curve is a near linear section by true origin.Get arbitrfary point m in the low-frequency range of mechanical admittance curves 9, then computing machine has also provided the coordinate figure that m order: fm=31.25Hz, (V/F) m ≈ 0.0018 substitution formula Qd=0.014[fm/ (V/F) m in the mechanical admittance curves 9 of this foundation pile of output]=0.014 (31.25/0.0018) try to achieve foundation pile test bearing capacity Qd=243 (t) and find corresponding state adjustment coefficient η according to Qd value on state adjustment coefficient curve 10
Q=1.3, substitution formula Qa=Qd/ η
Q=243/1.3 calculates the bearing capacity Qa=187 (t) of this foundation pile.
State is adjusted coefficient curve and (is claimed Qd-η again
QCurve.Accompanying drawing 3) is that dynamic and static contrast test is carried out in a collection of representative stake,, calculates by analysis and an exponential function curve obtaining that the ordinate representative state of this curve is adjusted coefficient η according to test figure
Q, the horizontal ordinate correspondence be the test value Qd of pile bearing capacity.
Claims (4)
1. low-strain transient admittance state regulation factor method that detects pile bearing capacity, it is characterized in that: adopt low frequency broad pulse power rod, at foundation pile jacking row transient impact exciting, its transient impact power is recorded by the force cell on the power rod, and dynamic response is received by the sensor that is installed in the foundation pile top; Transient force signal and dynamic response signal are simultaneously by the collector collection, through Computer Processing, draught machine is drawn the transient admittance curve of reflection pile-soil system dynamic characteristic, on the low-frequency range of this curve, get a little, obtain the test value (Qd) of pile bearing capacity and find state adjustment coefficient (η by state adjustment curve according to this test value (Qd)
Q), adjust coefficient (η with this state
Q) test value (Qd) is revised, can obtain the bearing capacity (Qd) of this foundation pile.
2. the low-strain transient admittance state regulation factor method of detection pile bearing capacity according to claim 1 is characterized in that described its frequency of low frequency broad pulse is 10Hz～300Hz, and pulse width is 5～20ms.
3. the low-strain transient admittance state regulation factor method of detection pile bearing capacity according to claim 1, it is characterized in that: measured transient admittance curve is to be horizontal ordinate with response frequency (f), ratio (V/F) with response speed and transient impact power is the curve of ordinate, and the low-frequency range of this curve is a near linear section by true origin.
4. according to the low-strain transient admittance state regulation factor method of claim 1 described detection pile bearing capacity, it is characterized in that: it is be horizontal ordinate with pile bearing capacity test value (Qd) that state is adjusted coefficient curve, with state adjustment coefficient (η
Q) be the exponential function curve of ordinate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97104326 CN1164643A (en) | 1997-05-21 | 1997-05-21 | Low-strain transient admittance state regulation factor method for detecting bearing capacity of foundation pile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 97104326 CN1164643A (en) | 1997-05-21 | 1997-05-21 | Low-strain transient admittance state regulation factor method for detecting bearing capacity of foundation pile |
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| CN1164643A true CN1164643A (en) | 1997-11-12 |
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| CN 97104326 Pending CN1164643A (en) | 1997-05-21 | 1997-05-21 | Low-strain transient admittance state regulation factor method for detecting bearing capacity of foundation pile |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102877490A (en) * | 2012-09-18 | 2013-01-16 | 河海大学 | Method for detecting quality of large-diameter tubular pile at low strain |
| CN106978825A (en) * | 2017-04-10 | 2017-07-25 | 广州市夯展科技发展有限公司 | Measure the low strain dynamic method of architecture foundation pile bearing capacity |
| CN109487835A (en) * | 2018-09-30 | 2019-03-19 | 中国铁道科学研究院集团有限公司铁道建筑研究所 | The detection method and detection device of pile foundation allowable bearing |
| CN110670643A (en) * | 2019-09-23 | 2020-01-10 | 朔黄铁路发展有限责任公司 | Method, device and system for detecting bearing capacity of pile group foundation and storage medium |
| CN110984145A (en) * | 2019-12-06 | 2020-04-10 | 江苏长江机械化基础工程有限公司 | Pipe pile construction monitoring method and monitoring equipment |
-
1997
- 1997-05-21 CN CN 97104326 patent/CN1164643A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102877490A (en) * | 2012-09-18 | 2013-01-16 | 河海大学 | Method for detecting quality of large-diameter tubular pile at low strain |
| CN102877490B (en) * | 2012-09-18 | 2014-06-11 | 河海大学 | Method for detecting quality of large-diameter tubular pile at low strain |
| CN106978825A (en) * | 2017-04-10 | 2017-07-25 | 广州市夯展科技发展有限公司 | Measure the low strain dynamic method of architecture foundation pile bearing capacity |
| CN109487835A (en) * | 2018-09-30 | 2019-03-19 | 中国铁道科学研究院集团有限公司铁道建筑研究所 | The detection method and detection device of pile foundation allowable bearing |
| CN110670643A (en) * | 2019-09-23 | 2020-01-10 | 朔黄铁路发展有限责任公司 | Method, device and system for detecting bearing capacity of pile group foundation and storage medium |
| CN110984145A (en) * | 2019-12-06 | 2020-04-10 | 江苏长江机械化基础工程有限公司 | Pipe pile construction monitoring method and monitoring equipment |
| CN110984145B (en) * | 2019-12-06 | 2021-06-01 | 中煤长江基础建设有限公司 | Pipe pile construction monitoring method and monitoring equipment |
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