小型桩基竖向循环加载模型试验系统研制与应用

doi:10.13722/j.cnki.jrme.2019.0631

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Abstract A small-scale vertical cyclic loading system for model tests of pile foundations，consisting of a loading system，a pressure chamber，a lifting device，model piles and a data acquisition system，is introduced. The model pile top is vertically loaded through a rotating roller screw driven by a coupler which is controlled by a servo motor，and soils samples are exerted with the confining pressure by hydraulic loading in order to simulate the in suit stress and consolidation of soil layers at different depths. The small-scale vertical cyclic loading system can be applied to carry out model tests of different pile foundations under vertical cycle loading in saturated soft soil，general clay，silty soil，sandy soil and other homogeneous or heterogeneous soils. Model tests of single pile under vertical cyclic loading are carried out and numerical simulation is performed for verification. Results show that the dynamic load amplitude and the consolidation pressure have great influence on the bearing capacity of the pile foundation. When the dynamic load amplitude is small，the bearing capacity of the pile foundation hardly weakens. When the consolidation pressure of the foundation soil increases，the bearing capacity of the pile foundation will be significantly enhanced，and the weakening will slow down. With increasing the cycle number and the amplitude，the axial force of the pile top gradually weakens to the residual value. During the cyclic loading，the degradation of the soil around the pile leads to a negative friction resistance of the pile foundation，and the bearing capacity of the pile foundation is weakened significantly. The test results are in good agreement with those obtained by the numerical simulation. Preliminary application proves that the test system can make up for the deficiency of low confining pressure in conventional 1 g small scale model test and that the nonlinear relationship between the load and the displacement of the pile top and that the cyclic degradation of the bearing capacity can be well reflected. This test system can output accurate load waveform，has high sensitivity and good stability in measurement and can be used to study the vertical cyclic loading characteristics of pile foundations under multiple working conditions.

Key words： pile foundation model test vertical cyclic loading numerical simulation degradation of bearing capacity

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	Articles by authors
	LIU Ying1
	2
	XU Panlong1
	HUANG Maosong3
	GAN Qing4
	MA Shaokun1
	2
	YANG Kai1

Cite this article:

LIU Ying1,2,XU Panlong1, et al. Development and application of a small-scale vertical cyclic loading system for model tests of pile foundations[J]. , 2020, 39(2): 374-383.

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http://rockmech.whrsm.ac.cn/EN/10.13722/j.cnki.jrme.2019.0631 OR http://rockmech.whrsm.ac.cn/EN/Y2020/V39/I2/374

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