重型动力触探杆长修正问题的研究

发布时间：2018-06-14 11:46

本文选题：动力触探 + 修正系数　；参考：《沈阳建筑大学》2015年硕士论文

【摘要】：动力触探(DPT:dynamic penetration test)作为现场原位测试手段之一,具有试验设备相对简单、操作起来方便、适应土类较为广泛、效率高、并且可以连续贯入等优点,在工程界应用较为广泛。实测触探击数需根据杆长进行折减修正才可用于评价岩土参数。但现行国家规范和地方规范中对杆长修正深度和击数都有一个限值,例如《岩土工程勘察规范》GB50021-2001(2009版),只给出了杆长20米以内的修正系数。实际生产过程中,动力触探还是标准贯入度试验实际使用深度已远远超过20m,甚至到lOOm以上,对于超过限定深度的动探击数如何修正目前尚没有统一规定。动力触探的理论基础大致可分为两部分,一部分是以弹性杆牛顿碰撞理论为理论基础,它的特点是杆长修正系数随着杆长的增加而减小。另一部分是以弹性波动理论为理论基础,该理论特点是杆长修正系数随着杆长的增加而增大,最后等于1。本文结合工程实例数据,利用数值分析软件,对动力触探进行数值模拟试验并将模拟出的结果与工程实例和参考文献进行比对与总结。研究成果也可作为标准贯入试验结果的杆长修正的参考。本文主要进行了以下几个方面的研究工作：(1)通过收集大量的工程实测数据,并进行一定的室内试验、现场试验,研究卵石和砂土的物理力学特性和相关参数；(2)本文在研究重型动力触探试验的一般机理、技术要求和工程应用的基础上,着重分析重型动力触探试验在工程实例中的卵石土层的应用特点和参数修正；(3)利用数值模拟软件,建立动力触探模型。通过对触探杆和土体模型简化确定,以及触探杆和土体之间的接触方式的选取,最终建立起初始模型。然后根据工程实例数据对该数值模型进行试算,得到的结果与工程实际作对比。验证模型的可行性；(4)通过对卵石、中砂两种土体的模拟验算,得到不同土体在2m、8.9m、16.4m、 23.4m、30m、36m、50m时的修正系数与杆长的曲线关系。得到不同土体对杆长修正系数的影响程度。
[Abstract]:As one of the in-situ testing methods, DPT: dynamic penetration test has the advantages of relatively simple test equipment, convenient operation, wide adaptability to soil, high efficiency and continuous penetration. It is widely used in engineering field. The measured penetration number can be used to evaluate geotechnical parameters only by modifying the length of rod. However, there is a limit to the corrected depth and hit number of rod length in the current national and local codes, such as the Geotechnical Engineering Prospecting Code (GB50021-20012009), and only the correction coefficient of the length of the rod within 20 meters is given. In the actual production process, the actual application depth of dynamic penetration test or standard penetration test has far exceeded 20m, even above lOOm. At present, there is no uniform regulation on how to correct the number of dynamic penetration over the limited depth. The theoretical basis of dynamic penetration detection can be divided into two parts. One part is based on the Newton collision theory of elastic rod. Its characteristic is that the correction coefficient of rod length decreases with the increase of rod length. The other part is based on elastic wave theory, which is characterized by that the correction coefficient of rod length increases with the increase of rod length and is equal to 1. In this paper, the numerical simulation test of dynamic penetration is carried out by using numerical analysis software combined with engineering case data, and the simulated results are compared and summarized with engineering examples and references. The research results can also be used as a reference for the correction of the standard penetration test results. In this paper, the following aspects of the research work: 1) through the collection of a large number of engineering data, and a certain number of indoor tests, field tests, to study the pebble and sand physical and mechanical properties and related parameters; 2) based on the study of the general mechanism, technical requirements and engineering application of the heavy-duty dynamic penetration test, the application characteristics and parameters correction of the heavy-duty dynamic penetration test in the pebble soil layer in the engineering example are emphatically analyzed in this paper. 3) using numerical simulation software to establish dynamic penetration model. The initial model was established through the simplified determination of the sounding rod and soil model and the selection of the contact mode between the sounding rod and the soil. Then the numerical model is calculated according to the engineering example data, and the result is compared with the engineering practice. To verify the feasibility of the model, the relationship between the correction coefficient and the rod length of different soils at 2mm ~ 8.9m ~ 16.4m, 23.4m ~ 30m ~ 36m ~ (50 m) was obtained through the simulation and calculation of pebble and middle sand soil. The influence degree of different soil on the correction coefficient of rod length is obtained.
【学位授予单位】：沈阳建筑大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU413

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