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A method for measuring pile displacement and internal force caused by expansion of foundation soil in expansive soil

A measurement method and technology of expansive soil, applied in the field of measurement of pile displacement and internal force caused by expansion of expansive soil foundation soil, can solve problems such as large difference, and achieve the effect of small calculation amount, precise calculation and clear force transmission

Active Publication Date: 2017-12-05
CHINA ROAD & BRIDGE +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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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  • A method for measuring pile displacement and internal force caused by expansion of foundation soil in expansive soil
  • A method for measuring pile displacement and internal force caused by expansion of foundation soil in expansive soil
  • A method for measuring pile displacement and internal force caused by expansion of foundation soil in expansive soil

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Experimental program
Comparison scheme
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 height of the swelling on 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 . ...

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Abstract

The purpose of the present invention is to provide a method for measuring pile displacement and internal force caused by expansive soil foundation soil expansion, to accurately and quickly determine the pile foundation internal force and displacement caused by expansive soil expansion. The present invention measures the size and material parameters of pile foundation and expansive soil ; Through the obtained parameters, calculate the equivalent spring stiffness of the non-expansive soil in the lower layer and the soil at the pile tip, and apply the spring to the pile section at the bottom of the expansive soil; obtain the differential control equation for the displacement of the pile foundation in the expansive soil range; for the displacement function Taylor Expand, and according to the pile top boundary condition and the spring boundary condition at the pile section at the bottom of the expansive soil, the calculation formula for solving the pile displacement and internal force caused by the expansion of the expansive soil foundation soil is obtained. The above method can accurately calculate the uplift force and uplift displacement generated by the expansive soil on the pile under the expansion condition with a relatively small calculation cost.

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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Patent Type & Authority Patents(China)
IPC IPC(8): G06F17/50
Inventor 杨军张大峰李植淮熊仕伶杨杰
Owner CHINA ROAD & BRIDGE