CN104345028A - Pile soil sliding friction testing method - Google Patents

Pile soil sliding friction testing method Download PDF

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Publication number
CN104345028A
CN104345028A CN201410579273.6A CN201410579273A CN104345028A CN 104345028 A CN104345028 A CN 104345028A CN 201410579273 A CN201410579273 A CN 201410579273A CN 104345028 A CN104345028 A CN 104345028A
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CN
China
Prior art keywords
friction
sliding friction
soil
pile
test
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201410579273.6A
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Chinese (zh)
Inventor
汤连生
胡永强
罗珍贵
桑海涛
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Sun Yat Sen University
National Sun Yat Sen University
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National Sun Yat Sen University
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Publication date
Application filed by National Sun Yat Sen University filed Critical National Sun Yat Sen University
Priority to CN201410579273.6A priority Critical patent/CN104345028A/en
Publication of CN104345028A publication Critical patent/CN104345028A/en
Pending legal-status Critical Current

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Abstract

The invention relates to a testing method for simulating the static friction and the sliding friction of pile soil. On the basis of a direct shearing instrument of soil, necessary improvement is made for simulating the sliding friction of pile soil, and a special pile soil sliding friction testing instrument is designed, so that the static friction and the sliding friction of pile soil can be tested under different bearing stratum conditions, and the static friction and the sliding friction of pile soil can be relatively well measured under different testing conditions. By using a special shearing box, the situation that the contact area is changed in an ordinary shearing process is effectively avoided; as springs for simulating a soil body are additionally arranged, the shearing speed is increased, and the measurement on the friction of pile soil with a bearing stratum and without a bearing stratum can be relatively well completed.

Description

The native sliding friction method of testing of stake
Technical field:
The present invention relates to static friction and sliding friction analog detection method between a kind of stake soil, belong to the innovative technology of static friction and friction friction testing between stake soil.
Background technology:
Along with the extensive use of static pressed pile, the theoretical research of static pressed pile causes the attention of engineering circles.The sinking mechanism of static pressed pile, the friction of ageing scheduling theory all and between stake soil of bearing capacity are closely related.Therefore, the friction problem between stake soil causes the attention of numerous scholars, and many scholars have carried out the indoor friction test between stake soil.But there is no the test apparatus of stiction and force of sliding friction between special detective pole soil both at home and abroad, is all carry out in direct shear apparatus, ring shear apparatus or the test of design certain moduli type.Wherein, ring shear apparatus instrument is more expensive, and model test wastes time and energy, and cost is high, and direct shear apparatus is directly the simplest, and testing expenses are low, therefore adopt maximum test apparatuses to be direct shear apparatus at present.But direct shear apparatus shear rate is slower, the shortcomings such as friction does not reach the sliding speed in pile driving process, the shear area in shear history changes, the change that can not simulate friction force between stake soil when stake runs into supporting course between stake soil, well can not reflect the friction between Jacked Pile Driving king-pile soil.In order to simulate the friction problem between Jacked Pile Driving king-pile soil exactly, direct shear apparatus being improved, making it the requirement meeting research.
Summary of the invention:
In order to simulate the sliding friction between pile driving process king-pile soil, the present invention improves direct shear apparatus, and devise special down cut box (see Fig. 3), by design material of body of a pile width 6.5cm, slightly larger than soil sample diameter, to guarantee that contact area remains constant in whole friction process, avoid the shortcoming of area change in traditional direct shear process, length is 10cm, ensures that sliding friction is carried out in enough displacements; Down cut box is also provided with spring, simulation stake end run into compared with during hard stratum on the impact of friction force between stake soil, spring can be arranged by the modulus in compression of actual place supporting course, utilize the spring of different modulus in compression to simulate Changing Pattern that piles with different end runs into different soil pile side resistance; From static to slip time corresponding friction force be stiction, record force of sliding friction in sliding process.The shear rate of conventional magnetic shear instrument is less, is usually less than 0.8mm/min, much smaller than the pile sinking speed of 2 ~ 3m/min, therefore improves the shear rate of direct shear apparatus.Test apparatus transforms on the basis of direct shear apparatus, and process of the test is similar in direct shear apparatus.Test unit schematic diagram is shown in Fig. 2, can be divided into: shear box (comprise shear box and down cut box, upper shear box is then improved to as shown in Figure 3 with conventional direct shear apparatus, down cut box), loading system and measuring equipment four part composition.Whole test unit is divided into shears gear train, vertical load system, balance bob and counterweight four parts (see Fig. 1).
Fig. 1 (test unit figure) and Fig. 2 (test unit schematic diagram) each several part are described as follows: 1. shear gear train; 2. vertical load system; 3. balance bob; 4. counterweight; 5. down cut box; 6. material of body of a pile; 7. go up shear box; 8. permeable stone; 9. piston; 10. soil sample; 11. measure one's own ability ring; 12. scales; 13. scales; 14. springs; 15. balls.
Accompanying drawing illustrates:
Fig. 1 test unit figure
Fig. 2 test unit schematic diagram
Fig. 3 down cut box
Embodiment:
(1) install sample, 100mm × 65mm made by material of body of a pile sample, and soil sample diameter is 61.8mm, high 2mm.Material of body of a pile sample and soil sample are carried out saturated before the test.
(2) apply Vertical dimension load, test and carry out under different vertical loads, trial load presses 100kPa, and 200kPa, 300kPa, 400kPa apply, and adjust balance bob, ensure that sample bears pressure at right angle in process of the test.
(3) applying level makes to rub between soil sample and material of body of a pile to shear stress, from static to slip, and the peak value determination limit stiction f surveyed by dial gauge in ring of measuring one's own ability su:
f su=cR (1)
In formula, R is ring dial gauge reading (0.01mm) of measuring one's own ability, and c is ring calibration coefficient (kPa/0.01mm) of measuring one's own ability.During sliding friction, (spring does not work) determines force of sliding friction by the stable reading of dial gauge in ring of measuring one's own ability by formula (1); After spring works, camber of spring is respectively 1cm, and the force of sliding friction when reading of dial gauge determines that stake affects by supporting course in ring of measuring one's own ability corresponding when 2cm, 3cm changes.
(4) according to the friction force under different vertical load, friction factor when determining coefficient of friction of rest, the coefficient of sliding friction and affect by supporting course.
(5) clearness test device, concentrated maintenance.

Claims (5)

1. measure the method for stake soil static friction and sliding friction for one kind, it is characterized in that measuring the static friction under different supporting course condition between stake soil and sliding friction, the measurement avoiding sample in conventional magnetic shear instrument process of the test to cause lifting surface area change because shearing the changing of the relative positions causing is inaccurate, and adopting varying strength spring to simulate supporting course, test supporting course is on the impact of sliding friction between stake soil.
2. the stake soil sliding friction test method required by right 1, it is characterized in that down cut box, place material of body of a pile within it, the wide 65mm of material of body of a pile, soil sample diameter is 61.8mm, ensure that whole process of the test contact area does not change, the long 100mm of material of body of a pile, ensure that the friction kinetic friction between stake soil has enough length.
3. according to the requirement of right 1, it is characterized in that being provided with ball between down cut box and testing table, reduce the friction between material of body of a pile and testing table.
4. according to the requirement of right 1, it is characterized in that from material of body of a pile and the soil body from the static extreme value occurred to sliding friction state procedure as limit stiction, using during stabilized speed sliding friction as sliding friction, be force of sliding friction when affecting by supporting course when spring works.
5. according to the requirement of right 4, it is characterized in that improve shear rate, ensure to occur sliding friction between material of body of a pile and soil.
CN201410579273.6A 2014-10-14 2014-10-14 Pile soil sliding friction testing method Pending CN104345028A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201410579273.6A CN104345028A (en) 2014-10-14 2014-10-14 Pile soil sliding friction testing method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201410579273.6A CN104345028A (en) 2014-10-14 2014-10-14 Pile soil sliding friction testing method

Publications (1)

Publication Number Publication Date
CN104345028A true CN104345028A (en) 2015-02-11

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104764690A (en) * 2015-03-31 2015-07-08 电子科技大学 Dynamic and static friction experimental device for eliminating speed effect
CN105910920A (en) * 2016-06-22 2016-08-31 青岛理工大学 Temperature control pile-soil interface direct shear test device
CN106092877A (en) * 2016-08-28 2016-11-09 无锡鸿海龙船机有限公司 A kind of confficient of static friction detector
CN106153229A (en) * 2015-04-10 2016-11-23 北京强度环境研究所 Normal temperature and the device of hot environment measurement composite radome fairing joint face frictional force
CN106442311A (en) * 2016-11-30 2017-02-22 燕山大学 Shear friction test device for pressure-bearing granular medium under vibration condition
CN114250880A (en) * 2021-12-31 2022-03-29 同济大学 Recycled concrete shearing vibration isolation device

Citations (4)

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US3443425A (en) * 1967-04-19 1969-05-13 Max Factor & Co Shear testing machine
US3465576A (en) * 1966-10-14 1969-09-09 Us Army Soil shear deformation tester
CN102628767A (en) * 2012-03-23 2012-08-08 河海大学 Device and method for testing mechanical properties of pile-soil contact surface
CN104034606A (en) * 2014-06-03 2014-09-10 同济大学 Multifunctional geotechnical synthesized material interface direct shear apparatus

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3465576A (en) * 1966-10-14 1969-09-09 Us Army Soil shear deformation tester
US3443425A (en) * 1967-04-19 1969-05-13 Max Factor & Co Shear testing machine
CN102628767A (en) * 2012-03-23 2012-08-08 河海大学 Device and method for testing mechanical properties of pile-soil contact surface
CN104034606A (en) * 2014-06-03 2014-09-10 同济大学 Multifunctional geotechnical synthesized material interface direct shear apparatus

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104764690A (en) * 2015-03-31 2015-07-08 电子科技大学 Dynamic and static friction experimental device for eliminating speed effect
CN104764690B (en) * 2015-03-31 2017-07-14 电子科技大学 A kind of sound frictional experiment device of release rate influence
CN106153229A (en) * 2015-04-10 2016-11-23 北京强度环境研究所 Normal temperature and the device of hot environment measurement composite radome fairing joint face frictional force
CN106153229B (en) * 2015-04-10 2018-11-30 北京强度环境研究所 The device of room temperature and hot environment measurement composite material radome fairing joint face frictional force
CN105910920A (en) * 2016-06-22 2016-08-31 青岛理工大学 Temperature control pile-soil interface direct shear test device
CN106092877A (en) * 2016-08-28 2016-11-09 无锡鸿海龙船机有限公司 A kind of confficient of static friction detector
CN106442311A (en) * 2016-11-30 2017-02-22 燕山大学 Shear friction test device for pressure-bearing granular medium under vibration condition
CN114250880A (en) * 2021-12-31 2022-03-29 同济大学 Recycled concrete shearing vibration isolation device

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Application publication date: 20150211