深层回灌影响下中环高架长期变形分析

发布时间：2018-09-18 12:56

【摘要】：高架道路作为上海的重要基础工程,是上海交通网络建设的命脉,其安全运营是城市发展的基石。然而,受上海地面沉降的影响,高架道路发生了较大的变形。为了保障高架道路的正常运营,上海采取限制地下水开采以及深层地下水回灌等措施,以此来减小地面沉降及其对高架道路的影响。在深层地下水回灌的影响下,上海的地面沉降得以控制,但同时也使得深部土体产生一定量的隆起,高架桩基持力层较深,从而受深部土体隆沉变化的影响也更大。为了探究深层回灌影响下高架桩基长期变形的特性,本文以上海中环高架为工程背景,根据长期沉降监测结果,分析了中环高架浦西段的变形特性及其与地面沉降的相互作用关系,并采用数值模拟方法,研究了深层地下水回灌对中环高架桩基长期变形特性的影响,主要的工作内容如下:(1)对上海中环高架路浦西段不同地质条件进行系统分类,结合高架长期沉降和邻近地面沉降监测数据,分析了中环高架桩基沉降与区域地面沉降的相互作用关系,研究了地质结构条件对高架桩基沉降的影响。研究表明,正常沉积区中地面及高架桩基沉降最小,且有微量隆起,⑥层缺失区中地面及高架桩基的沉降最大。高架桩基整体变形趋势与区域地面沉降相吻合且高架沉降始终小于地面沉降,其变形量与深部土层最为接近。(2)基于Biot固结理论,采用地下水流量控制的流固耦合分析方法模拟深层地下水的抽灌过程,对季节性变流量抽灌作用下的土体与桩基沉降特征进行数值模拟分析。中环线典型桩基的数值分析与测试结果基本吻合,证明该方法可以有效地反应深层地下水回灌对大地和高架变形的长期影响。数值分析表明,季节性回灌使得高架及土体变形随季节发生波动,浅部土层仍在地表荷载作用下发生固结沉降,深部土体不断隆起,高架桩基在上部荷载和深层回灌耦合作用下呈现先沉降后隆起的现象,其长期沉降受深部土层隆沉位移的影响更大。(3)采用经过典型断面测试结果验证的数值分析方法,对影响高架桩基长期变形的主要因素进行参数分析,研究了地质条件、回灌点位置、回灌点深度、流量大小、桩基长度等因素对高架及大地沉降的影响,分析总结了深层回灌荷载影响高架桩基变形的基本规律:当回灌点与高架桩基的水平间距越小,回灌深度越深,回灌流量越大,桩基持力层越深时,则回灌对高架桩基的长期变形影响也越大,高架桩基将在回灌荷载作用下沉降减小,并逐步上抬。
[Abstract]:As an important basic project in Shanghai, viaduct is the lifeblood of traffic network construction in Shanghai, and its safe operation is the cornerstone of urban development. However, due to the influence of land subsidence in Shanghai, the viaduct has been deformed. In order to ensure the normal operation of the viaduct, Shanghai has taken measures such as restricting the exploitation of groundwater and recharging the deep groundwater in order to reduce the land subsidence and its influence on the viaduct. Under the influence of deep groundwater recharge, the ground subsidence in Shanghai can be controlled, but at the same time, the deep soil mass has a certain uplift, and the bearing layer of the elevated pile foundation is deeper, which is more affected by the uplift and subsidence of the deep soil mass. In order to explore the long-term deformation characteristics of elevated pile foundation under the influence of deep recharge, this paper takes Shanghai Central elevated as the engineering background, and according to the long-term settlement monitoring results, The deformation characteristics of the central elevated Puxi section and its interaction with the ground subsidence are analyzed, and the effect of deep groundwater recharge on the long-term deformation characteristics of the central elevated pile foundation is studied by using the numerical simulation method. The main contents are as follows: (1) the different geological conditions in Puxi section of Shanghai Central Viaduct are systematically classified, and the monitoring data of long-term subsidence and adjacent land subsidence are combined. The interaction between the settlement of the central elevated pile foundation and the regional land subsidence is analyzed, and the influence of the geological structure on the settlement of the elevated pile foundation is studied. The results show that the settlement of ground and elevated pile foundation is the smallest in the normal sedimentary area, and the settlement of the ground and elevated pile foundation is the largest in the area with trace uplift and 6 missing layers. The deformation trend of elevated pile foundation is consistent with that of regional ground subsidence, and the settlement of elevated pile foundation is always smaller than that of ground settlement, and its deformation is most close to that of deep soil layer. (2) based on Biot consolidation theory, The fluid-solid coupling analysis method of groundwater flow control is used to simulate the process of deep groundwater pumping and irrigation, and the settlement characteristics of soil and pile foundation under seasonal variable discharge pumping and irrigation are analyzed numerically. The numerical analysis of typical pile foundation in the middle ring line is in good agreement with the test results, which proves that this method can effectively reflect the long-term influence of deep groundwater recharge on the deformation of the earth and the elevated ground. The numerical analysis shows that seasonal recharge causes the deformation of the elevated soil and soil to fluctuate with the season, the shallow soil is still consolidated and settled under the action of the surface load, and the deep soil is constantly uplifted. Under the coupling action of upper load and deep recharge, the vertical pile foundation presents the phenomenon of first settlement and then uplift, and its long-term settlement is more affected by the uplift displacement of deep soil layer. (3) the numerical analysis method verified by typical section test results is adopted. The main factors affecting the long-term deformation of elevated pile foundation are analyzed, and the effects of geological conditions, recharge point location, depth of recharge point, flow rate and pile foundation length on the settlement of the elevated pile and the earth are studied. This paper analyzes and summarizes the basic law that deep recharge load affects the deformation of elevated pile foundation: when the horizontal distance between the recharge point and the elevated pile foundation is smaller, the depth of recharge is deeper, the recharge flow is larger, and the bearing layer of pile foundation is deeper. The effect of recharge on the long-term deformation of the elevated pile foundation is also greater, and the settlement of the elevated pile foundation will be reduced under the action of recharge load and gradually lifted up.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U443.1

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