【作者】 高博；

【导师】 张鸿儒；

【作者基本信息】 北京交通大学 ， 岩土工程， 2010， 博士

【摘要】 碎石桩复合地基在工程上的广泛应用使其在抗液化方面的显著效果得到了工程实践的验证。虽然碎石桩复合地基在地震过程中一般不会发生液化,但复合地基也经常会因为震后附加沉降而伴随有震害发生。目前对碎石桩复合地基在动荷载作用下地震响应和震后沉降情况研究较少,实测资料和地震震害资料更少。所以对碎石桩复合地基的震后沉降问题进行有针对性的研究是对碎石桩复合地基理论体系完善和补充的必要环节。借助振动台模型试验对碎石桩复合地基的震后沉降规律做了探索性的试验研究工作,课题主要进行了以下工作：1.对叠层剪切模型箱的关键零部件从机械角度进行了全面的分析设计研制。新研制的模型箱具有受力机制合理、可循环操作性高、整体稳定性好、质量小、强度高、不漏水等突出特点。2.进行了完整的振动台方案设计,试验在振动台模型箱中成功的采用了振动沉管成桩工艺来模拟施工现场的振动沉管法。试验还采用可调节钢管内支撑的方式成功的解决了叠层剪切模型箱中常见的漏砂漏水问题。3.对饱和砂土地基和碎石桩复合地基的地震加速度响应和孔压发展规律进行了分析研究。对孔压消散开始时间的影响因素进行了分析,并分析了碎石桩复合地基在动荷载作用下,附加压重投影面积下的桩土应力比的变化规律。4.进行了饱和砂土地基和不同成桩方法、不同桩径、不同桩间距的碎石桩复合地基振动台模型试验。找到了砂土地基和碎石桩地基在无附加压重和有附加压重两种情况下震后即时沉降和震后最终沉降的比例和规律,绘制出了砂土地基和碎石桩复合基地震后12小时内的沉降曲线。通过试验结果对震后即时沉降的影响因素进行了总结,并对碎石桩复合地基震后的沉降规律进行了详尽的分析,对碎石桩复合地基减小地基震后沉降的效果进行了评价。5.建立了预估砂土地基震后沉降简化公式,公式结合了土的动力参数,并用振动台模型试验结果进行了对比验证。同时,针对振动台模型试验进行了数值模拟分析。更多还原

【Abstract】 There are agreements that Vibro replacement stone columns are in use can mitigate liquefaction hazards in sandy soils for almost three decades.But the post-earthquake settlement of stone columns can also induce earthquake disaster.The research of earthquake response and post-earthquake settlement of stone columns composite foundation during dynamic load is not enough now.And actual measurement and earthquake disaster information of stone columns com-posite foundation is fewer. So the research to stone columns composite foundation settlements is a important part and supplement to the whole theory of composite foundation.A shaking table experiment for stone columns have been made to find the characteristic of stone columns settlement.The following work have been made in this project.1. Technical development has been made to the laminar shear model box after the comprehensive analysis of the key accessories of the laminar shear model box.The deadweight of the new devel-oped model box decreases, and the force mechanism of the model box is more close to the actual one of soil. Equipment can be reused, and its operation capability is better than before.2. The whole scheme of shaking table test have been made. During stone column installa-tion,vibrator have been used to simulate the real construction of stone column installation in this experiment. Support system which inside with adjustable steel pipe have been used to solve the water creep problem in the laminar box.3. Analyse and research have been made to saturated sandy soil foundation and stone columns composite foundation earthquake acceleration response and the rule of development of excess pore water pressure. And analyse have been made to pile-soil stress ratio under upper load during dynamic load.4. A shaking table experiment for saturated sandy soil foundation and stone columns composite foundation have been made,and stone columns composite foundation use the different stone column installation and the different diameter of column and the different pile spacing. The pro-portion between instantaneous settlement and total settlement have been found through the ex-periment. And drawing the post-earthquake settlement curve in 12 hours of stone columns com-posite foundation and saturated sandy soil foundation.And elaborate analyse have been made to post-earthquake settlement.Assess of minishing settlements result have been made based on ex-periment result.5. Adopting dynamic parameter of sandy soil, a simple and practical method of estimating soil set-tlements is established. The shaking table test data have been used to verify the proposed method. And numerical simulation also have been made to shaking table test.更多还原