【作者】 万小全；

【导师】 张良；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2013， 硕士

【摘要】 近年来,CFG桩复合地基已广泛应用于高速铁路路基工程的地基处理中。但是沉降计算方面的理论研究仍落后于工程实践,其中沉降计算经验系数因缺乏实测资料仍按照建筑地基基础下的复合地基经验系数取值。现有研究成果表明路堤荷载下的复合地基具有明显不同于建筑基础下的复合地基的性质,前者属于柔性基础下的复合地基,后者属于刚性基础下的复合地基。目前急需广泛积累现场实测资料,提出适用于高速铁路路堤荷载作用下CFG桩复合地基的沉降计算经验系数。针对这一问题,本文做了如下工作：(1)收集了京津城际、京沪高速铁路共7个CFG桩复合地基断面的现场地基沉降实测资料,地勘资料及设计参数,并进行了数据整理。(2)采用分层总和法计算各断面复合地基的总沉降,将计算总沉降与各断面的预测最终沉降比较,得出各断面的沉降计算经验系数。计算中,压缩层厚度分别采用应力比法和变形控制法确定；天然土层的压缩模量分别取由100kPa至200kPa的压力段对应的压缩模量即标准模量和实际压力段对应的压缩模量。(3)采用现行规范的沉降计算经验系数,对单一模量法与e-p曲线法的计算总沉降进行修正,将修正后的总沉降与预测总沉降进行了比较分析。分析表明,e-p曲线法的计算结果与预测最终沉降的差距较小,更适合深厚软弱土层的沉降计算。(4)对e-p曲线法的压缩层当量压缩模量与沉降计算经验系数计算结果进行了分析,给出了铁路路堤荷载作用下不同当量压缩模量时的CFG桩复合地基沉降计算经验系数取值,与建筑地基所给的推荐值相比前者更大。可以认为高速铁路深厚层软弱土CFG桩复合地基的沉降计算采用建筑地基推荐的沉降计算经验系数偏于不安全。更多还原

【Abstract】 In recent years, the CFG pile composite foundation has been widely used in high-speed railway foundation treatment. But the settlement calculation of theoretical research still lags behind in engineering practice, including the settlement calculation empirical coefficient due to a lack of measured data is still value in accordance with the empirical coefficient of composite foundation under the building foundation. The recent research shows that the characteristic of composite foundation under embankment differ from which under the building foundation. The former one is under flexible foundation, while the latter one is under rigid foundation. There is an urgent need to extensive accumulation of the field measurement data, suitable for high-speed railway embankment load CFG pile composite foundation settlement calculation empirical coefficient. To solve this problem, the following work is done:(1) Collection of the Beijing-Tianjin inter-city, the Beijing-Shanghai high-speed railway of7CFG pile cross-section of the site foundation settlement measured data, the geological survey data and design parameters, and data processing.(2) Based on the layerwise summation method, composite modulus is used to calculate the total settlement of the composite foundation. In the total settlement of composite foundation calculation, the compression layer thickness can be defined by the stress ratio method or deformation ratio control method.In the calculation of the composite modulus, corresponding to the two methods above-mentioned,the natural soil compression modulus has two definition,one is modulus under100kPa to200kPa pressure segment i.e. standard modulus, and the other one is that under actual pressure section.(3)The the total settlements calculated by the single modulus method and e-p curve method are amended by using the current specification empirical coefficient.Compare them with the forecast total settlement, it is found that the e-p curve method of calculation results are closer to the predicted final settlement. That means the e-p curve method is more suitable for deep soft soil settlement calculation.(4) the equivalent compression modulus of compression layer in the E-p curve method and the results of settlement empirical coefficient are analyzed. And the values of the empirical coefficient of CFG pile composite foundation settlement calculation in the condition of different equivalent compression modulus under the railway embankment loads are proposed. They are greater than the recommended values of the construction foundation. The paper shows that it is unsafe to use the empirical coefficient of settlement calculation that the building foundation recommended applied to the settlement calculation of CFG pile composite foundation of soft soil deep layer of high-speed railway.更多还原