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Method for measuring pile displacement and internal force caused by soil expansion of expansive soil foundation

A measurement method and technology of expansive soil are applied in the field of measurement of pile displacement and internal force caused by expansion of expansive soil foundation soil, which can solve problems such as large difference

Active Publication Date: 2015-10-07
CHINA ROAD & BRIDGE +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the analytical solution formulas of scholars do not consider the above factors, and the calculated results are quite different from the actual situation. The analysis shows that the gap can reach 50%.

Method used

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  • Method for measuring pile displacement and internal force caused by soil expansion of expansive soil foundation
  • Method for measuring pile displacement and internal force caused by soil expansion of expansive soil foundation

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Experimental program
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Effect test

Embodiment 1

[0053] Donaldson once buried a concrete pile with a diameter of 9in (22.86cm) and a length of 34ft (10.36m) in the expansive soil foundation, with a depth of 30ft (9.144m).

[0054] Poulos&Davis calculated and analyzed the pile using layered calculation method, and deduced the analytical solution formula (assuming constant expansion rate and stiffness) and calculated the test.

[0055] The calculation parameters in this paper are as follows: the elastic modulus of the pile is 20.69GPa; the expansive soil pile-soil spring stiffness is proportional to the depth k 0 =0, λ=3.217×10 6 N / m 3 , non-expansive soil pile-soil spring stiffness k 2 =2.12×10 7 N / m 2 , the spring stiffness at the bottom of the pile is 0 due to disengagement; the uplift of the ground S 0 =9mm, at the expansion depth h 0 = Within 15ft (4.57m), it decreases linearly with depth to zero.

[0056] Calculated using the theoretical formula in this paper, and compared with the calculation results and experime...

Embodiment 2

[0059] Zhang Chunshun used Nanning expansive soil for model tests. The test was carried out in an oil drum with a diameter of 50 cm and a height of 90 cm. The bottom of the drum was filled with 10 cm thick pebbles and fine sand, 12 cm thick loess (not expansive), and then 58 cm thick Nanning expansive soil (a medium expansive soil). The model pile adopts a PVC pipe with a diameter of 5.0cm, which is filled with fly ash mixture. The pile length is 65cm, buried in the soil 58cm, and there is no load on the top of the pile.

[0060] The model material parameters are as follows: the elastic modulus EP of the model pile body is 1.82GPa, and the swelling height of the top surface of the expansive soil is 3.5cm. The Poisson's ratio of the soil is v=0.3, and the expansion depth is 0.58m. Within the expansion depth, the uplift of the expansive soil along the depth changes linearly. Expansive soil pile-soil spring stiffness proportional to depth, k 0 =0, λ=1.79×10 7 N / m 3 .

[006...

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Abstract

The present invention aims to provide a method for measuring the pile displacement and internal force caused by soil expansion of an expansive soil foundation so as to rapidly and accurately determine the internal force and displacement of a pile foundation caused by by expansion of expansive soil. According to the method, the sizes of the pile foundation and the expansive soil and material parameters are measured; according to the measured parameters, the equivalent spring stiffness of non-expansive soil on the lower layer and pile end soil is calculated, and a spring acts on the cross section of the pile at the bottom of the expansive soil; a differential control equation of the pile displacement within the scope of the expansive soil is acquired; and a displacement function is subjected to Taylor expansion, and according to a pile top boundary condition and a spring boundary condition on the cross section of the pile at the bottom of the expansive soil, a computational formula for solving the pile displacement and internal force caused by soil expansion of the expansive soil foundation is acquired. With the adoption of the method, the up-dragging force and up-dragging displacement of the pile caused by the expansive soil under the expansion condition are accurately calculated through less calculation.

Description

technical field [0001] The invention relates to the field of pile foundation design in expansive soil foundations, in particular to a method for measuring pile displacement and internal force caused by expansion of expansive soil foundation soil. Background technique [0002] With the rapid development of my country's highway construction and the implementation of the "Great Overseas" strategy, the highway construction of Chinese enterprises at home and abroad has entered a new peak. However, expansive soil known as "highway cancer" often appears in engineering construction, which seriously affects the use of roads and endangers engineering safety. As a more effective treatment method for expansive soil foundation, pile foundation can effectively reduce the uplift of the road and reduce the uneven settlement of the road. The construction department urgently needs to know the extent of the impact of expansive soil on the pile foundation, and whether the additional stress and...

Claims

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Application Information

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IPC IPC(8): G06F19/00
Inventor 杨军张大峰李植淮熊仕伶杨杰
Owner CHINA ROAD & BRIDGE