CN113175006A - Novel pile foundation vertical load settlement curve prediction method - Google Patents

Novel pile foundation vertical load settlement curve prediction method Download PDF

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Publication number
CN113175006A
CN113175006A CN202110357983.4A CN202110357983A CN113175006A CN 113175006 A CN113175006 A CN 113175006A CN 202110357983 A CN202110357983 A CN 202110357983A CN 113175006 A CN113175006 A CN 113175006A
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pile
load
target
frictional resistance
side frictional
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CN113175006B (en
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蔡奇鹏
杨哲瑜
杜进金
陈星欣
苏世灼
刘永淼
林浩
蔡叶沁
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Huaqiao University
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    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D33/00—Testing foundations or foundation structures
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D27/00—Foundations as substructures
    • E02D27/10—Deep foundations
    • E02D27/12—Pile foundations
    • E—FIXED CONSTRUCTIONS
    • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
    • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
    • E02D2600/00—Miscellaneous
    • E02D2600/10—Miscellaneous comprising sensor means

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  • Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Mining & Mineral Resources (AREA)
  • Paleontology (AREA)
  • Civil Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Structural Engineering (AREA)
  • Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)

Abstract

The invention provides a novel method for predicting a vertical load settlement curve of a pile foundation, which comprises the steps of selecting a test pile, applying pile top loads Q at all levels, and measuring a corresponding pile top displacement value s0(ii) a Obtaining the pile body compression amount through the distribution of the pile body axial force N along with the depth z, and obtaining the pile end displacement value s 'under the load of all levels of pile tops'0(ii) a Obtaining the mapping relation between the pile side frictional resistance and the pile top load at different depth positions of each soil layer through the differential relation between the pile body axial force N and the pile side frictional resistance tau and the distribution curve of the pile side frictional resistance along with the depth, and establishing a mapping database; when the load settlement curve of the target pile is predicted, the pile side frictional resistance in the mapping database is called in proportion according to the pile top load of the target pile and the soil layer condition, and the pile top settlement value s of the target pile under the action of all levels of loads is obtained according to the differential relation between the pile side frictional resistance and the axial force of the pile bodyiFinally, obtaining a load settlement curve of the target pile; the method provided by the inventionThe method can quickly obtain the vertical load settlement curve of the pile foundation, saves economic cost, improves efficiency, has clear principle and is easy to realize.

Description

Novel pile foundation vertical load settlement curve prediction method
Technical Field
The invention relates to the field of on-site foundation soil surveying, in particular to a novel method for predicting a vertical load settlement curve of a pile foundation.
Background
When the construction side carries out the settlement detection of the vertical load of the pile foundation on the spot, a large amount of manpower and time cost are needed to be spent due to the large number of the pile foundations, so that the construction period is prolonged, and the economic cost is improved. How to improve efficiency in pile foundation load settlement detection, no mature technical method exists at present, and research personnel are urgently needed to explore.
Disclosure of Invention
The invention mainly aims to overcome the defects in the prior art, and provides a novel method for predicting the vertical load settlement curve of the pile foundation, which can quickly obtain the vertical load settlement curve of the pile foundation, save the economic cost, improve the efficiency, has a clear principle and is easy to realize.
The invention adopts the following technical scheme:
the novel method for predicting the vertical load settlement curve of the pile foundation is characterized by comprising the following steps of:
selecting foundation piles meeting the conditions as test piles according to the field soil layer drilling investigation result;
measuring the displacement value s of the corresponding pile top by applying the pile top loads Q of all levels0；
The pile body pressure is obtained by measuring the distribution of the axial force N of the pile body of the test pile along with the depth zThe amount of shrinkage is carried out, and a pile end displacement value s 'under the load of pile tops of all levels is obtained'0；
Obtaining a distribution curve of the pile side frictional resistance along with the depth under the load of each level of pile top through the differential relation between the pile body axial force N and the pile side frictional resistance tau;
obtaining the mapping relation between the pile side frictional resistance and the pile top load at different depth positions of each soil layer according to the distribution curve of the pile side frictional resistance along with the depth, and establishing a mapping database of the pile side frictional resistance and the pile top load according to the types of the soil layers;
when the load settlement curve of the target pile is predicted, according to the pile top load and the soil layer condition of the target pile, proportionally calling the pile side frictional resistance in the mapping database to obtain a distribution curve of the pile side frictional resistance of the target pile under the horizontal action of each level of load along with the depth;
according to the differential relation between the side friction resistance of the pile and the axial force of the pile body, the distribution of the axial force of the pile body of the target pile along with the depth under the action of each stage of load is obtained, and the pile top settlement value s of the target pile under the action of each stage of load is further obtainediAnd finally obtaining the load settlement curve of the target pile.
Specifically, strain gauges are arranged on the pile body of the test pile at certain intervals, and the distance between the strain gauges is not smaller than half of the thickness of the minimum soil layer.
Specifically, by applying pile top loads Q of all stages, measuring corresponding pile top displacement values s0The method also comprises the following steps:
and after each stage of load is applied, confirming that all pile body axial force sensors are stable, acquiring effective data, and applying the next stage of load.
Specifically, the method calls the pile side frictional resistance in the mapping database in proportion to obtain a distribution curve of the pile side frictional resistance along with the depth under the action of each level of load level of the target pile, and further comprises the following steps:
and when the target pile side frictional resistance mapping database is called, scaling according to the vertical effective stress level at the calculation point to obtain a new pile side frictional resistance distribution curve along with the depth of the target pile under the horizontal action of each level of load.
Specifically, according to the differential relation between the pile side frictional resistance and the pile body axial force, the method further comprises the following steps of obtaining the distribution of the pile body axial force of the target pile along with the depth under the action of each level of load: and obtaining new pile end resistance and recalculating the compression amount of the pile body.
Specifically, the method further comprises the following steps:
when the bearing layer of the target pile is the same as the bearing layer where the test pile is located, determining the rigidity coefficient of the bearing layer according to the vertical load test result of the test pile, and further calculating the settlement value of the target pile under the pile end load;
and when the bearing layer of the target pile is different from the bearing layer where the test pile is positioned, adding a new test pile so as to obtain the rigidity coefficient of the corresponding bearing layer, and then calculating the settlement value of the target pile under the pile end load.
Specifically, a pile top settlement value s of the target pile under the action of each level of load is obtainediAnd finally obtaining a load settlement curve of the target pile, wherein the load settlement curve specifically comprises the following steps:
and after the pile end of the target pile under each level of load is settled through calculation, adding the pile body compression amount to obtain the pile top settlement under each level of load, thereby finally obtaining the vertical load settlement curve of the target pile.
As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:
(1) the invention provides a novel method for predicting a vertical load settlement curve of a pile foundation, which comprises the following steps of selecting foundation piles meeting conditions as test piles according to a site soil layer drilling investigation result; measuring the displacement value s of the corresponding pile top by applying the pile top loads Q of all levels0(ii) a Obtaining the pile body compression amount through the distribution of the pile body axial force N of the measurement test pile along with the depth z, and obtaining the pile end displacement value s 'under the load of the pile tops of all levels'0(ii) a Obtaining a distribution curve of the pile side frictional resistance along with the depth under the load of each level of pile top through the differential relation between the pile body axial force N and the pile side frictional resistance tau; obtaining the mapping relation between the pile side frictional resistance and the pile top load at different depth positions of each soil layer according to the distribution curve of the pile side frictional resistance along with the depth, and establishing a mapping database of the pile side frictional resistance and the pile top load according to the types of the soil layers; when the load settlement curve of the target pile is predicted, the load of the pile top of the target pile is usedAnd the soil layer conditions, calling the pile side frictional resistance in the mapping database according to the proportion to obtain a distribution curve of the pile side frictional resistance along with the depth of the target pile under the horizontal action of each level of load; according to the differential relation between the side friction resistance of the pile and the axial force of the pile body, the distribution of the axial force of the pile body of the target pile along with the depth under the action of each stage of load is obtained, and the pile top settlement value s of the target pile under the action of each stage of load is further obtainediFinally, obtaining a load settlement curve of the target pile; the method provided by the invention can quickly obtain the vertical load settlement curve of the pile foundation, saves the economic cost, improves the efficiency, has clear principle and is easy to realize.
Drawings
FIG. 1 is a diagram of a field layout provided by an embodiment of the present invention;
wherein: 1. drilling a hole; 2. target piles; 3. and (6) testing the pile.
Detailed Description
The invention is further described below by means of specific embodiments.
The method comprises the following steps: carrying out detailed geological drilling on the site before prediction, and ensuring that drilling hole sites contain all target pile positions; the position of the test pile is selected near a drilling hole at the most abundant place of the soil layer of the field, so that each soil layer can obtain corresponding side friction resistance information; fig. 1 is a layout diagram of a site provided by an embodiment of the present invention, wherein 1 is a drill hole; 2 is a target pile; and 3, a test pile.
Step two: selecting foundation piles near the drill holes with the most abundant soil layers as test piles, wherein enough strain gauges are arranged on the pile bodies of the test piles at certain intervals (such as 0.5m), the interval between the strain gauges is not smaller than half of the thickness of the minimum soil layer, and a group of four strain gauges is uniformly arranged at each position in a surrounding mode;
step three: by applying pile top loads Q (e.g. 10, 20, 30, 40, 50 tons) at various stages, the corresponding pile top displacement value s is measured0Obtaining a load settlement curve of the test pile;
step four: obtaining the pile body compression amount through the distribution of the pile body axial force N of the strain gauge measurement test pile along with the depth z, and obtaining the pile end displacement value s 'under the load of all levels of pile tops'0；
Step five: obtaining a distribution curve of the pile side frictional resistance along with the depth under the load of each level of pile top through the differential relation between the pile body axial force N and the pile side frictional resistance tau;
step six: acquiring a mapping relation between the pile side frictional resistance and the pile top load at different depth positions of each soil layer according to the distribution curve of the pile side frictional resistance tau along with the depth z under the pile top load of each level obtained in the step five, and establishing a mapping database of the pile side frictional resistance and the pile top load according to the types of the soil layers;
step seven: when the load settlement curve of the target pile is predicted, according to the pile top load of the target pile and the soil layer condition, the pile side frictional resistance in the mapping database is called in proportion to obtain a distribution curve of the pile side frictional resistance along with the depth under the horizontal action of each level of load of the target pile;
step eight: according to the differential relation between the side frictional resistance of the pile and the axial force of the pile body, the distribution of the axial force of the pile body of the target pile along with the depth under the action of each level of load is obtained, and the pile body compression amount of the target pile is further obtained;
step nine: when the bearing layer of the target pile is the same as the bearing layer where the test pile is located, the rigidity coefficient of the bearing layer can be determined according to the vertical load test result of the test pile, so that the settlement value of the target pile under the pile end load is further calculated, and when the bearing layer of the target pile is different from the bearing layer where the test pile is located, a new test pile needs to be added, so that the rigidity coefficient corresponding to the bearing layer is obtained;
step ten: and e, after the pile end of the target pile under each level of load is settled in the ninth step, adding the pile body compression amount to obtain the pile top settlement under each level of load, and finally obtaining the vertical load settlement curve of the target pile.
The method can be used for predicting the vertical load settlement curve of the pile foundation, and has the characteristics of saving economic cost and improving efficiency.
The above description is only an embodiment of the present invention, but the design concept of the present invention is not limited thereto, and any insubstantial modifications made by using the design concept should fall within the scope of infringing the present invention.

Claims (7)

1. The novel method for predicting the vertical load settlement curve of the pile foundation is characterized by comprising the following steps of:
selecting foundation piles meeting the conditions as test piles according to the field soil layer drilling investigation result;
measuring the displacement value s of the corresponding pile top by applying the pile top loads Q of all levels0；
Obtaining the pile body compression amount through the distribution of the pile body axial force N of the measurement test pile along with the depth z, and obtaining the pile end displacement value s 'under the load of the pile tops of all levels'0；
Obtaining a distribution curve of the pile side frictional resistance along with the depth under the load of each level of pile top through the differential relation between the pile body axial force N and the pile side frictional resistance tau;
obtaining the mapping relation between the pile side frictional resistance and the pile top load at different depth positions of each soil layer according to the distribution curve of the pile side frictional resistance along with the depth, and establishing a mapping database of the pile side frictional resistance and the pile top load according to the types of the soil layers;
when the load settlement curve of the target pile is predicted, according to the pile top load and the soil layer condition of the target pile, proportionally calling the pile side frictional resistance in the mapping database to obtain a distribution curve of the pile side frictional resistance of the target pile under the horizontal action of each level of load along with the depth;
according to the differential relation between the side friction resistance of the pile and the axial force of the pile body, the distribution of the axial force of the pile body of the target pile along with the depth under the action of each stage of load is obtained, and the pile top settlement value s of the target pile under the action of each stage of load is further obtainediAnd finally obtaining the load settlement curve of the target pile.
2. The method for predicting the vertical load settlement curve of the novel pile foundation according to claim 1, wherein the strain gauges are arranged on the pile body of the test pile at regular intervals, and the spacing between the strain gauges is not less than half of the minimum soil layer thickness.
3. The method for predicting the vertical load settlement curve of the novel pile foundation according to claim 1, wherein the load Q of the pile tops at all levels is applied to measureCorresponding pile top displacement value s0The method also comprises the following steps:
and after each stage of load is applied, confirming that all pile body axial force sensors are stable, acquiring effective data, and applying the next stage of load.
4. The method for predicting the vertical load settlement curve of the novel pile foundation according to claim 1, wherein the pile side frictional resistance in the mapping database is called in proportion to obtain a distribution curve of the pile side frictional resistance along with the depth of the target pile under the action of each level of load level, and the method further comprises the following steps:
and when the target pile side frictional resistance mapping database is called, scaling according to the vertical effective stress level at the calculation point to obtain a new pile side frictional resistance distribution curve along with the depth of the target pile under the horizontal action of each level of load.
5. The method for predicting the vertical load settlement curve of the novel pile foundation according to claim 1, wherein after the distribution of the axial force of the pile body of the target pile along with the depth under the action of each stage of load is obtained according to the differential relation between the side frictional resistance of the pile and the axial force of the pile body, the method further comprises: and obtaining new pile end resistance and recalculating the compression amount of the pile body.
6. The method for predicting the vertical load settlement curve of the novel pile foundation according to claim 1, further comprising:
when the bearing layer of the target pile is the same as the bearing layer where the test pile is located, determining the rigidity coefficient of the bearing layer according to the vertical load test result of the test pile, and further calculating the settlement value of the target pile under the pile end load;
and when the bearing layer of the target pile is different from the bearing layer where the test pile is positioned, adding a new test pile so as to obtain the rigidity coefficient of the corresponding bearing layer, and then calculating the settlement value of the target pile under the pile end load.
7. The method for predicting the vertical load settlement curve of the pile foundation according to claim 5, wherein the method comprisesIs characterized in that the pile top settlement value s of the target pile under the action of all levels of loads is obtainediAnd finally obtaining a load settlement curve of the target pile, wherein the load settlement curve specifically comprises the following steps:
and after the pile end of the target pile under each level of load is settled through calculation, adding the pile body compression amount to obtain the pile top settlement under each level of load, thereby finally obtaining the vertical load settlement curve of the target pile.
CN202110357983.4A 2021-04-01 2021-04-01 Method for predicting vertical load settlement curve of pile foundation Active CN113175006B (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102587426A (en) * 2012-04-05 2012-07-18 铁道第三勘察设计院集团有限公司 Analysis method for estimating bearing capacity of pile foundation on basis of penetration technology
CN105735373A (en) * 2016-03-11 2016-07-06 青岛理工大学 Measurement method of ultimate bearing capacity of prefabricated single pile
RU2015156942A (en) * 2015-12-30 2017-07-05 Федеральное государственное бюджетное учреждение науки Институт прикладной механики Российской академии наук (ИПРИМ РАН) The method of determining the bearing capacity of piles
CN108470225A (en) * 2018-03-21 2018-08-31 广东省交通规划设计研究院股份有限公司 The sedimentation information forecasting method and forecasting system of roadbed
CN111428297A (en) * 2020-03-23 2020-07-17 交通运输部公路科学研究所 BP neural network-based pile foundation P-S curve determination method
CN111827375A (en) * 2020-07-17 2020-10-27 中铁六局集团有限公司 Construction method for detecting foundation pile load based on self-balancing static load

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102587426A (en) * 2012-04-05 2012-07-18 铁道第三勘察设计院集团有限公司 Analysis method for estimating bearing capacity of pile foundation on basis of penetration technology
RU2015156942A (en) * 2015-12-30 2017-07-05 Федеральное государственное бюджетное учреждение науки Институт прикладной механики Российской академии наук (ИПРИМ РАН) The method of determining the bearing capacity of piles
CN105735373A (en) * 2016-03-11 2016-07-06 青岛理工大学 Measurement method of ultimate bearing capacity of prefabricated single pile
CN108470225A (en) * 2018-03-21 2018-08-31 广东省交通规划设计研究院股份有限公司 The sedimentation information forecasting method and forecasting system of roadbed
CN111428297A (en) * 2020-03-23 2020-07-17 交通运输部公路科学研究所 BP neural network-based pile foundation P-S curve determination method
CN111827375A (en) * 2020-07-17 2020-10-27 中铁六局集团有限公司 Construction method for detecting foundation pile load based on self-balancing static load

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