长短桩复合地基沉降试验与预测方法研究

发布时间：2018-06-14 08:55

本文选题：长短桩 + 复合地基　；参考：《华北科技学院》2017年硕士论文

【摘要】：随着建筑物向高层、深基方向发展,对于地基抵抗变形的要求越来越高,长短桩复合地基处理技术也因此在工程实践中发展起来。长短桩复合地基能充分发挥桩体和土体的特性,达到控制沉降、提高安全系数的目的。但是随着长短桩复合地基处理方式越来越复杂,其沉降引发的安全问题越来越突出。因此有必要对长短桩复合地基进行深入的研究。本文首先对长短桩复合地基的沉降变形和承载特性进行研究。然后对长短桩复合地基沉降计算方法进行比较分析。最后通过建立GA-SVM模型对长短桩复合地基进行沉降预测。主要研究内容和成果如下:(1)通过室内试验模型的建立,研究桩体的桩长、桩径、垫层厚度变化对沉降变形的影响,揭示长短桩复合地基的沉降变化规律。结果表明:增加长桩长度、短桩长度、桩径、减小垫层厚度对地基沉降控制有显著效果。(2)通过对长短桩复合地基的桩身应力、桩土应力比和下卧层应力进行分析,揭示长短桩复合地基的应力特性。结果表明:桩身应力会出现一个峰值,且该峰值处的桩身应力最大;桩顶的桩土应力比先增大后减小,桩端的桩土应力比逐渐增大;下卧层桩身应力相比周围土体应力较大。(3)结合工程实例对长短桩复合地基沉降计算方法进行分析,并对其沉降计算值与实测数据进行对比研究。结果表明:等效天然地基计算计算结果比较符合实际,加权模量法计算虽然比较简单,但是沉降计算的误差比较大。(4)通过GA-SVM预测模型对长短桩复合地基沉降进行预测研究。结果表明:GA-SVM对长短桩复合地基进行预测拟合程度较好,其沉降预测与现场实测值误差较小。本文提出的GA-SVM模型对长短桩复合地基沉降预测具有良好的预测精度和适用性,对于岩土工程的安全预测具有良好的指导作用。
[Abstract]:With the development of high building and deep foundation, the requirement of resisting deformation of foundation is more and more high, and the treatment technology of long-long pile composite foundation has been developed in engineering practice. Long and short pile composite foundation can give full play to the characteristics of pile and soil to control settlement and improve safety factor. But as the treatment of long and short pile composite foundation becomes more and more complex, the safety problems caused by its settlement become more and more prominent. Therefore, it is necessary to study the long-long pile composite foundation. In this paper, the settlement, deformation and bearing characteristics of long and short pile composite foundation are studied. Then the settlement calculation method of long and short pile composite foundation is compared and analyzed. Finally, GA-SVM model is established to predict the settlement of long-long pile composite foundation. The main research contents and results are as follows: (1) through the establishment of laboratory test model, the influence of pile length, pile diameter and cushion thickness on settlement deformation is studied, and the rule of settlement variation of long-long pile composite foundation is revealed. The results show that increasing the length of long pile, the length of short pile, the diameter of pile and reducing the thickness of cushion have remarkable effect on the control of foundation settlement. The stress characteristics of long and short pile composite foundation are revealed. The results show that there will be a peak value of pile stress, and the pile body stress at the peak value will be the largest, and the pile-soil stress ratio of the pile top will first increase and then decrease, and the pile-soil stress ratio at the end of the pile will increase gradually. Combined with engineering examples, the settlement calculation method of long-long pile composite foundation is analyzed, and the calculated value of settlement is compared with the measured data. The results show that the calculation results of the equivalent natural foundation are in good agreement with the reality. Although the calculation of weighted modulus method is simple, the error of settlement calculation is relatively large. 4) the settlement of long-long pile composite foundation is forecasted by GA-SVM model. The results show that the weight GA-SVM can predict the composite foundation with long and short piles, and the error between settlement prediction and field measurement is small. The GA-SVM model proposed in this paper has good prediction accuracy and applicability for the settlement prediction of long-long pile composite foundation, and has a good guiding function for the safety prediction of geotechnical engineering.
【学位授予单位】：华北科技学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU753

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