Test method for pile-soil load sharing ratio of pile group foundation

Abstract

The invention discloses a test method for a pile-soil load sharing ratio of a pile group foundation. According to the method, a displacement lifting device and inter-pile soil pressure boxes are adopted; the displacement lifting device comprises a lifting actuator, a displacement sensor, an axial force meter, an inner sleeve, an outer sleeve, an upper flange and a lower flange, and the displacement sensor and the axial force meter are connected with an external displacement monitor and an axial force monitor respectively; the average stress F0 of a pile top is measured by the axial force monitor, and the area S0 of the pile top is calculated; the inter-pile soil pressure boxes are buried at the bottom of a bearing platform and connected with an external pressure monitor, the average stressF1 of inter-pile soil is measured by the pressure monitor, and the area S1 of the inter-pile soil is calculated; the pile-soil load sharing ratio of the bearing platform under different settlement amounts is K, wherein K=(F0*S0) / (F1*S1). By means of the method, the pile-soil load sharing ratio coefficient can be quickly measured, the number of sets of in-situ tests or model tests can be significantly reduced, the operation is convenient, the test workload is greatly reduced, and the test cost is reduced.

Description

technical field [0001] The invention belongs to the technical field of pile foundation engineering, and in particular relates to a method for testing the pile-soil load sharing ratio of pile group foundations. Background technique [0002] With the development of urbanization, the application of large-scale pile group foundation is more and more widely. Different from single piles due to changes in properties such as settlement, model tests and engineering measurements have shown that under certain conditions, the bearing capacity of pile groups will be higher than the sum of the bearing capacity of single piles. Considering the resistance of the soil under the cap, it can be effectively Improving the bearing capacity of the pile group foundation has huge economic benefits. [0003] In "Technical Specifications for Building Pile Foundations" (JGJ94-2008), a calculation formula is proposed for the calculation of the characteristic value of the vertical bearing capacity of co...

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Problems solved by technology

[0003] In "Technical Specifications for Building Pile Foundations" (JGJ94-2008), a calculation formula is proposed for the calculation of the characteristic value of the vertical bearing capacity of composite foundation piles considering the cap effect, which effectively improves the level of vertical bearing capacity design of pile group foundations. The cost of the project is reduced. These calculation formulas do not consider the difference in soil resistance of the soil under the cap under different settlement conditions, and the value of the cap effect coefficient in the calculation formula is an interval under the same condition, but It is not clear about the specific value

Existing test methods for the pile-soil load sharing ratio of pile group foundations need to carry out pile-soil load sharing ratio tests under different combination conditions, such as pile diameter, pile length, cap size and settlement, etc., requiring a large number of in-situ tests or The model test is cumbersome to operate, and the test workload is huge, which not only reduces the work efficiency, but also increases the test cost

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