Study On The Model Experiment Of The Micro-Piles Composite Structure

Micro-pile is a type of small diameter bored pile of which the diameter is between 100 and 300mm..At first, micro-piles is considered as a whole structure to bear vertical loads. However, in recent 20 years, due to the development of micro-pile technology, the views on bearing capacity of micro-pile have been changed. It is gradually realized that single micro-pile is also able to resist lateral loads. It is helpful for engineers to apply micro-pile in supporting projects, especially in which the construction condition is constricted. As a result of the advantages of applying micro-pile, attentions are paid to micro-pile. Micro-piles are used in foundation pit supporting, slope controlling and reconstruction projects after earthquake. However, the theory on micro-pile applied in slope engineering falls far behind practice. In view of the research situation, it is an urgent task to start researches on anti-sliding mechanism of micro-pile composite structure. The main work and conclusions of this paper is as follows:(1)Collecting data on application and theory calculation of micro-pile at home and abroad and classifying it into different types,the anti-slide to be discussed in this paper micro-pile composite structure.(2)Displacement analysis model is built to analyze the displacement of pile top for independently distributed micro-pile system and plane frame micro-pile structure respectively. It can be deduced that plane frame micro-pile structure is better for decreasing slope displacement,controlling generation and development of fracture in rock-mass between two piles, and has more positive effect on slope stability.Focusing on micro-pile composite structure commonly used in practice and taking 2×2 and 3×3 pile group as an example, calculation models are built to analyze the internal force and stability of two kinds of structure: micro-pile group without bolt and micro-pile group with bolt. In addition, pile-soil interaction model is established on the basis of Winkler elastic foundation theory.(3)Model test is done to study the anti-sliding mechanism, deformation trend, distribution form of loads acted on micro-pile composite structure. The moment of micro-pile model is calculated by the data obtained from model test, thus analyzing the anti-sliding mechanism of micro-pile and load distribution. (4)Using Midas, a numerical analysis software, by use of the strong symbolic operation function of Midas,numerical simulation the micro-pile model test structure. And use numerical simulation results compare with experimental results and theoretical calculations, then we come to a reasonable result. And the reliability of theoretical calculations are verified by comparing the calculation results.