Microstructural Analysis Of Liquefied Soil Foundation Model Reinforced By Different Piles Before And After The Model Vibrate

The liquefaction of saturated sandy soil has always been the focus of geotechnical engineering research.In recent years earthquakes occur frequently,and liquefaction of saturated sand caused by the earthquake induced leads to a large of area damage of buildings, causing great damage to people’s life and property. Especially after the earthquake in Wenchuan, China paid more attention to disaster prevention and mitigation work of the field of construction.Thus,it has important significance that research the reinforcement of soil liquefaction. Processing method of sand liquefaction include cement-soil pile,gravel pile,etc. The research to macroscopic phenomena and various parameters of reinforcement model of the different pile types, has great contribution to studying the effective reinforcement method of liquefaction soil. This paper from the view of microscopic, deeply studies the reinforcement mechanism of soil liquefaction reinforced foundation by piles.In this paper, based on the national natural fund project(No. 50578104) "Study on reinforcement mechanism of liquefacted sandy soil reinforced by piles", Shanxi bureau of science and technology project(No. 10-1-06) "Study on the mechanism of liquefaction resistance of sand reinforced by piles in the loess area ", and the loess research laboratory of Shanxi Province open fund project(KLTLR- Y13-3) " Study on pile foundation bearing in the liquefied soil", 6groups of liquefied soil model is un-reinforced foundation, reinforced foundation by single cement-soil pile, reinforced foundation by single gravelpile, reinforced foundation by four cement-soil piles, reinforced foundation by four gravel pile and reinforced foundation by cement-soil piles and gravel piles,and make microscopic test respectively sampling from shaking table test.The void area ratio curve, images of specimens and histograms of pore distribution rate of different reinforcement methods are obtained from the test.Six sets of reinforcement models were analyzed respectively and comprehensively, and the following results were obtained:(1) after many tests, the method of making micro soil sample was obtained,and the best magnification and threshold selection method the this study are identified. The best method for this study is 500 times. The threshold of the gray distribution curve is in the trough.(2) The void area ratio of un-reinforced foundation, reinforced foundation by single cement-soil pile and reinforced foundation by four cement-soil piles after the model vibrate increases than before,and the maximum is at the deep 24 cm.Middle layers of the different soil all become loose with vibration load. The void area ratio of reinforced foundation by single gravel pile, reinforced foundation by four gravel piles and reinforced foundation by gravel piles and cement-soil piles after the model vibrate reduces than before,and the minimum is at the deep24 cm. It explains that the drainage effect of gravel pile makes the soil close,and the middle layers is more obvious.(3) Before vibrate in the model soil with the increase of the number of reinforced piles, the percentage of voids in the foundation model decreases. The effect of the cement-soil pile to reduce the pore of the soil is better.After vibrate,the effect of gravel pile to reinforce the soil is significantly more than that of cement soil pile. In the reinforced foundation by four cement-soil piles large pore distribution of shallow soil greatly reduced.The next is reinforced foundation by single gravel pile. The effect of other pile reinforcement model is not obvious. In the reinforced foundation by single gravel pile and four gravelpiles the effect of large pore distribution of middle layer soil reducing is good.The next is the reinforced foundation by cement-soil piles and gravel piles.The last one is reinforced foundation by four cement-soil piles.To sum up, in this experiment to reduce soil pore the effect of reinforced foundation by single gravel pile and four gravel piles is the best.To shallow and deep layer soil the effect of reinforced foundation by four cement-soil piles is good. To comprehensive consideration, to play the strengths of the two types of pile, the reinforced foundation by cement-soil piles and gravel piles is the most suitable to apply to practical engineering.