现场液化试验方法及液化土体特征研究

发布时间：2018-05-28 22:52

本文选题：现场试验 + 液化　；参考：《中国地震局工程力学研究所》2016年博士论文

【摘要】：液化问题是土动力学和岩土地震工程研究的重要课题之一。强震下饱和砂土易发生液化并可能加重震害,机械和波浪荷载下土体也存在液化问题。研究液化及相关工程问题,具有重要的理论和工程意义,一直是工程抗震领域的前沿方向。震害调查和室内试验是目前认识和研究液化问题的重要手段和主要手段。现场监测也是直接研究地震中液化问题的一种手段。在研究液化方面发挥了巨大作用,极大推动了对液化问题的认识,大量成果已经付诸工程实践。但上述手段存在着不足:震害调查要受限于大震发生的频率,也无法得到液化发展的过程;室内试验,难以全面复现真实场地的砂土液化过程;由于地震短临预报的不成熟性和强震的罕遇性,使得现场监测的效果大打折扣,迄今取到的研究成果极其有限。随着液化问题研究的深入,现场条件下直接开展试验成为一条新途径。这种方法可以从一个新的角度了解土体液化的响应规律。在此研究需求背景下,人工源震动下现场液化试验得到了发展,用于补充上述认识手段的不足,以便更好地掌握实际场地中土体液化响应规律和液化土体的特征。目前以此开展的研究,总体成果有限,国内更是处于起步阶段,需要大力发展。本文从现场液化试验这一新的手段和角度研究液化问题,通过发展和完善现场液化试验方法,研究现场条件下液化土体的孔压发展与加速度、应变的响应规律以及液化土体的特征,以期与已有试验手段得到的认识相互比对,相互验证,更深入地了解和掌握液化规律,发展液化分析方法。主要成果和工作包括:(1)研究了现场液化试验方法中人工震源、试验数据获取、液化土体特征量、试验组织与实现中的关键技术问题,发展完善了现场液化试验方法,设计了两种形式的现场液化试验,通过与以往液化试验和国际上已有同类试验相比,验证了试验的可靠性。(2)以现场液化试验手段,研究了液化对地表运动的影响,以求从一个新的角度得到地表运动与液化关联性的认识,得到了其液化水平与地表加速度的关系以及液化对地表运动的影响规律。(3)研究了水平场地孔压增长模式,寻找实际场地和室内试验孔压增长模式的区别和联系,以加速度、埋深、砂土类型等为基本指标构建了孔压增量模型,并通过数值模拟和其它同类现场试验验证了该孔压模型的可靠性。(4)以现场液化试验为基础,研究了场地条件下饱和砂土的孔压发展与剪应变的关系,提出了液化发展过程中孔压发展与剪应变关系的定量表达式。
[Abstract]:Liquefaction is one of the most important topics in soil dynamics and geotechnical seismic engineering. Saturated sand is prone to liquefaction and may aggravate earthquake damage under strong earthquake, and liquefaction problem also exists in soil under mechanical and wave loads. The study of liquefaction and related engineering problems has important theoretical and engineering significance, and has always been the frontier direction in the field of engineering earthquake resistance. Earthquake damage investigation and laboratory test are important means and main means to understand and study liquefaction problem. Field monitoring is also a method to study liquefaction in earthquake directly. It has played a great role in the research of liquefaction, greatly promoted the understanding of liquefaction, and a large number of achievements have been put into engineering practice. But there are some shortcomings in the methods mentioned above: the seismic damage investigation should be limited by the frequency of earthquake occurrence and the process of liquefaction development can not be obtained, and it is difficult to fully reproduce the liquefaction process of the real site through laboratory tests; Due to the immaturity of short-term and impending earthquake prediction and the rare occurrence of strong earthquakes, the effect of field monitoring is greatly compromised, and the research results obtained so far are extremely limited. With the development of liquefaction research, it is a new way to carry out direct test under field conditions. This method can be used to understand the response law of soil liquefaction from a new point of view. Under the background of this research demand, the field liquefaction test under artificial source vibration has been developed to supplement the deficiency of the above means, so as to better understand the response law of soil liquefaction and the characteristics of liquefaction soil in the actual site. At present, the overall results of the research are limited, the domestic is in the initial stage, need to be vigorously developed. In this paper, the liquefaction problem is studied from the new method and angle of field liquefaction test. By developing and perfecting the field liquefaction test method, the pore pressure development and acceleration of liquefaction soil under field conditions are studied. The response law of strain and the characteristics of liquefaction soil are expected to compare and verify with the existing experimental methods, to understand and master the liquefaction law more deeply, and to develop the liquefaction analysis method. The main achievements and work include: (1) the artificial seismic source in the field liquefaction test method, the acquisition of test data, the characteristic quantity of liquefaction soil, the key technical problems in the test organization and realization are studied, and the field liquefaction test method is developed and perfected. Two kinds of in-situ liquefaction tests are designed. Compared with the previous liquefaction tests and the similar tests in the world, the reliability of the tests is verified, and the effect of liquefaction on the surface motion is studied by means of in-situ liquefaction tests. In order to obtain the relationship between surface motion and liquefaction from a new angle, the relationship between liquefaction level and surface acceleration and the influence of liquefaction on surface motion are obtained. To find out the difference and relation of pore pressure growth mode between actual site and laboratory test, the increment model of pore pressure is constructed with acceleration, depth of burial and type of sand as the basic index. The reliability of the pore pressure model is verified by numerical simulation and other similar field tests. The relationship between pore pressure development and shear strain of saturated sand under site condition is studied on the basis of field liquefaction test. The quantitative expression of the relationship between pore pressure development and shear strain during liquefaction development is presented.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TU435

【参考文献】