深层土体侧向载荷试验探头的研制与应用

发布时间：2019-01-04 18:38

【摘要】：在岩土工程设计中,深层土体的静止侧压力系数、水平基床系数、不排水抗剪强度、承载力等是非常重要的设计参数,一般由室内土工试验及经验值取得,由于取样、运输及室内试验过程中对土体原始应力状态的影响,使所测得的参数无法反映现场土体的真实状况。因此,寻求一种简捷的原位测试技术估算上述参数是岩土工程工作者努力的方向。而目前常用的基于侧向载荷机理的扁铲侧胀试验、旁压试验和应力铲试验已经积累了较多的经验,但在应用中尚存在一定的局限性,对现有试验仪器进行改进与发展以满足实际工程的需求是必要的。为此,在自行研制的孔压位移扁铲探头的基础上进一步优化设计,研制出深层土体侧向载荷试验探头,通过现场试验验证,实现试验成果的初步应用,主要研究内容及成果如下：(1)在不改变传统扁铲探头规格的条件下,以微型刚性载荷板代替传统柔性膜片,利用弹性橡胶膜实现密封与载荷板的复位,刚性载荷板的侧向位移最大可达3mm,使得相对位移s/b达到0.05,理论上可以测得完整的p-s曲线。安装微型位移传感器,用于连续测量荷载板位移。安装孔压与土压元件,用于测量试验深度处土压力、孔隙水压力及进行孔压消散试验。简要介绍了深层土体侧向载荷试验的配套设备及试验原理。(2)选择连云港海边高压缩软土场地和南京虹桥漫滩相粉土场地进行深层土体侧向载荷试验及扁铲侧胀试验、十字板剪切试验等对比试验,对试验数据进行处理与初步分析,结果表明,深层土体侧向载荷试验可完成传统扁铲试验目标,且直接测得试验深度处原位静止土压力、真实完整的p-s曲线,超静孔隙水压力及其消散过程,试验资料更全面、直接地反映了试验土体的工程性质。(3)根据试验资料,探讨精确划分土层、简捷估算深层土体水平固结系数、静止侧压力系数、水平基床系数、承载力特征值等参数的方法,取得了较好的效果,实现一种试验获取多重参数的目的,满足工程实践的需要。
[Abstract]:In geotechnical engineering design, the static lateral pressure coefficient, horizontal bed coefficient, undrained shear strength and bearing capacity of deep soil are very important design parameters. The influence of transportation and indoor test on the original stress state of the soil makes the measured parameters can not reflect the real state of the field soil. Therefore, it is the direction of geotechnical engineers to seek a simple in situ testing technique to estimate the above parameters. However, many experiences have been accumulated in the flat-shovel dilatation test, pressure-pressure test and stress shovel test, which are based on lateral loading mechanism, but there are still some limitations in application. It is necessary to improve and develop the existing test instruments to meet the needs of practical engineering. For this reason, on the basis of the hole pressure displacement flat shovel probe developed by ourselves, a lateral load test probe for deep soil was developed, and the initial application of the test results was realized through field test. The main research contents and results are as follows: (1) under the condition of not changing the specifications of the traditional flat shovel probe, the traditional flexible diaphragm is replaced by the micro rigid load plate, and the seal and the reset of the load plate are realized by using the elastic rubber film. The maximum lateral displacement of the rigid load plate can reach 3 mm, which makes the relative displacement s / b reach 0.05, and the complete p-s curve can be measured theoretically. Install micro displacement sensor for continuous measurement of load plate displacement. Installation of pore pressure and soil pressure elements for measuring soil pressure at test depth, pore water pressure and pore pressure dissipation test. This paper briefly introduces the equipment and principle of lateral load test of deep soil. (2) the lateral load test and flat dilatation test of deep soil are carried out at Lianyungang seaside high compression soft soil site and Nanjing Hongqiao floodplain silt site. The experimental data are processed and preliminarily analyzed by contrast tests such as cross plate shear test. The results show that the lateral load test of deep soil can accomplish the traditional flat shovel test target, and directly measure the static earth pressure in situ at the depth of the test. The true and complete p-s curve, the excess pore water pressure and its dissipation process, the experimental data are more comprehensive and directly reflect the engineering properties of the tested soil. (3) according to the experimental data, the accurate division of soil layer is discussed. The method of estimating parameters such as horizontal consolidation coefficient, static lateral pressure coefficient, horizontal bed coefficient and bearing capacity characteristic value of deep soil is simple and effective. To meet the needs of engineering practice.
【学位授予单位】：南京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU415

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