【作者】 徐增杰；

【导师】 牛琪瑛；

【作者基本信息】 太原理工大学 ， 岩土工程， 2009， 硕士

【摘要】 饱和砂土在地震作用下易产生液化,对建筑物或构筑物产生破坏作用。对于如何预防砂土液化也成了岩土工程界的一个重要研究问题。水泥土桩是一种应用广泛的加固软土的处理措施,用水泥土桩加固液化砂土,目前被一些实际工程所采用,但对其抗液化性能和加固机理等方面的研究较少,在模拟地震荷载作用下,对水泥土桩加固模型地基的液化特征研究就更少了。鉴于此,本文依托国家自然科学基金资助项目“桩体加固液化砂土作用机理的试验研究”(项目号50578104),主要进行了以下三方面工作:从太原市漪汾桥北约5公里处取土约1吨,筛选试验用的砂土,制备试验用的水泥土桩;制备三种不同密实度(1.45g/cm3、1.55g/cm3、1.65g/cm3)的模型地基;对未加固模型地基和水泥土桩体加固模型地基进行振动台试验,对试验中所得到的孔隙水压力、孔隙水压力比、承压板的沉降量等资料进行分析。试验结果表明:未加固地基在振动过程中,从浅层到深层地基的超静孔压比都在1.1左右,表明土体全部液化,深层的孔压比大于浅层和中部的孔压比,说明地基的下部的液化程度比下部大;从振动过程中分析得出,浅层和中部的孔压比比深层的先达到峰值,说明液化先从地基上部开始逐渐发展到深部。未加固模型地基随着密实度的增大,同一位置的孔压比有减小的趋势,即抗液化能力有增大的趋势。水泥土桩加固地基在振动过程中,在同一密度情况下,超静孔隙水压力随着深度的增加而增大。孔压比也随着深度的增加而增大,进而液化的趋势随深度的增加而增大。表明液化先在下部发生;在不同密度情况下,水泥土桩加固地基在振动过程中,随着密度的增大,测量位置的孔压比有所减小,即随着地基密度的增大,抗液化能力有所提高。承压板的沉降量随着密度的增加而减小,说明有承台作用的加固液化土体具有明显的抗液化效果;在同一密度情况下,有承压台的水泥土桩加固地基的抗液化能力强于比无承台的加固地基的抗液化能力。更多还原

【Abstract】 The saturated sandy soil is easy to have the trend of liquefication under the earthquake force, which has the destruction to the building or the construction.the prevention of sandy soil liquefaction has also become an important subject in geotechnical engineering.soil-cement pile has been widely used in soft-soil ground. soil-cement pile is carried out consolidating on liquefiable ground by a few practical engineering, but studies on anti-liquefaction mechanism of soil-cement pile and reinforcement mechanism is rare.The study on the liquefaction characteristics of saturated sand ground improved by soil -cement pile under under modeling the earthquake force is poorer.In response to these circumstances ,under the support of National Science Fund Project“The experimental study on mechanism of piles improving liquefiable soil”(No.50578104), The following three parts of the experimental study have been made :soil used in the experiment is from Yi Fen Bridge north about 5 kilometers and soil-cement piles have been made; Three different types of dry densities (1.45g/cm3,1.55g/cm3,1.65g/cm3) model ground have been made;Pore water pressure、pore water pressure ratio and bearing plate settlement are analyzed in non-improved and improved soil.The experimental results indicate that, In non-improved soil, the excess pore water pressure ratio reached nearly the same value of 1.1 in all the three layers, so the entire layer liquefied. However, the excess pore water pressure ratio in the deeper layer was a little smaller than in the middle and shallow layers. Among the liquefaction levels of the three layers, the deep layer was the highest. The time of excess pore water pressure reached peak in the deeper layer was longest, so the liquefaction region firstly appeared in shallow layer, then penetrated to the deeper. At last, the entire layer liquefied.with the increase of the ground density ,the pore water pressure of the same location become smaller ,it is said that the ability of anti-liquefaction is improved;In the vibration of soil-cement pile under the same density, the excess pore water pressure ratio and the excess pore water pressure are improved with increasing depth.it is said that the trend of liquefaction is increased with increasing depth. Liquefaction occurred at the lower part ;In the process of vibration of soil-cement pile ground in different density , As the density increases, the pore pressure has been reduced in the same measurement location, that is to say ,as the ground density increased, the ability of anti-liquefaction is improved.With the increase in density, the settlement of bearing plates is reduced,which has a clear effect of anti-liquefaction; In the same density, the ability of anti-liquefaction of soil-cement pile with bearing plate is stronger than the anti-liquefaction capacity of the ground without bearing plate.更多还原