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基于Weibull曲线的软基沉降预测模型分析 总被引：2，自引：0，他引：2
结合软基沉降机理,提出用Weibull模型预测软基沉降全过程。该预测模型参数意义较为明确,可以反映加载速度等因素的影响,克服了其它两种成长模型反弯点处沉降值与最终沉降相对不变的缺点。在利用其它模型预测时,只有初步判断实测样本反弯点的位置才能较科学的选择有效样本和相应模型进行预测。Weibull模型可以充分利用沉降观测样本,具有广泛的适应性,指数模型是它的一种退化形式。它不但可以预测线性加载的软基沉降,而且可以预测一次加载或近似一次加载的软基沉降。工程实例的实测和计算比较说明该模型是可靠的。 相似文献
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路基沉降预测的三点修正指数曲线法 总被引：2，自引：0，他引：2
科学、合理地预测路基工后沉降量是高速铁路建设的关键环节。针对武广高速铁路路基沉降量级小、数据相对波动大的实测数据,探讨了指数曲线法对无砟轨道路基沉降预测的适用性,发现指数曲线法不能直接应用于量级小、数据相对波动较大的沉降预测。把三点法的基本思想引入指数曲线模型,对指数曲线法进行了改进,提出了路基沉降预测的三点修正指数曲线模型。结合武广高速铁路路基沉降观测数据,分析了三点修正指数曲线模型的特性。分析表明,在整个沉降曲线上选取3个关键点作为预测样本,很好地回避了数据波动带来的影响;沉降曲线上“拐点”以后的沉降规律更符合指数曲线模型,因此,应取沉降曲线上“拐点”以后的数据作为样本值,所取三点应能尽量反映沉降发展的趋势。三点修正指数曲线法预测结果稳定、相关系数高,具有一定的工程应用价值 相似文献
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地基固结沉降随机有限元计算和可靠度分析 总被引：4，自引：0，他引：4
基于比奥（Biot）固结理论，采用邓肯-张本构模型，考虑随机场的影响，首次给出了地基固结沉降随机有限元分析方法，并基于随机有限元对点固结沉降和差异固结沉降的可靠度进行了分析。 相似文献
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基于一个非线性粘弹性本构模型描述土体的蠕变特性，建立了有限元模型，对某工程中使用EPS作换填材料所产生的效果进行了计算模拟，讨论了主次固结沉降以及超固结状态的影响，探讨了工程中产生较大工后沉降的原因，预测了工程的远期沉降量，探讨了在该类工程中设计EPS的原则和方法。 相似文献
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对真空堆载预压加固处理的软土地基,用灰色理论模型预测地基的分层沉降,结果表明：对于土层分布均匀的地基,verhulst模型能较准确地预测分层沉降,误差在10％以内。对于土层分布不均匀的地基,verhulst模型预测误差较大,进行残差修正,修正的verhulst模型能较准确地预测分层沉降。用不同点数预测地基的分层沉降,同实测沉降数据对比发现、对于土层均匀或不均匀的软土地基,在已知真空影响范围外土层的沉降时,灰色模型就能较准确地预测分层沉降。 相似文献
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高填石路堤蠕变本构模型及其参数反演分析与应用 总被引：1，自引：0，他引：1
结合高填石路堤工后沉降变形机理与工程特点，基于工程实测数据，提出了高填石路堤工后沉降蠕变变形的双曲线型三参数本构模型，并引进遗传算法与有限元分析理论，建立了该模型参数的反演分析方法。在此基础上，利用蠕变有限元分析手段，深入探讨了高填石路堤工后沉降的分析计算方法，并开发了相应的分析计算软件。结合某高填石路堤工程实践，探讨了高填石路堤双曲线三参数蠕变本构模型和高填石路堤工后沉降计算的应用方法。工程实例分析表明，提出的本构模型及其工后沉降计算方法简单，可以满足工程要求，初步建立了一种新的高填石路堤工后沉降计算方法。 相似文献
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Application of grey theory-based model to prediction of land subsidence due to engineering environment in Shanghai 总被引：7，自引：0，他引：7
Yi-Qun Tang Zhen-Dong Cui Jian-Xiu Wang Li-Ping Yan Xue-Xin Yan 《Environmental Geology》2008,55(3):583-593
Land subsidence is a common geological hazard. The long-term accumulation of land subsidence in Shanghai has caused economic
loss to the city. Since the 1990s, the engineering structures have become a new cause of land subsidence. Many factors affect
the process of land subsidence. Although such a process cannot be explicitly expressed by a mathematical formula, it is not
a “black box” whose internal structure, parameters, and characteristics are unknown. Therefore, the grey theory can be applied
to the prediction of land subsidence and provides useful information for the control of land subsidence. In this paper, a
grey model (GM) GM (1, 1) with unequal time-intervals was used to predict the subsidence of a high-rise building in the Lujiazui
area of Shanghai, and the results were compared with the monitored data. The prediction of subsidence was also corroborated
by laboratory tests and the results were compared with measured data and the predicted data by the adaptive neuro-fuzzy inference
system (ANFIS). It is found that the GM (1, 1) with unequal time-intervals is accurate and feasible for the prediction of
land subsidence. 相似文献
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Numerical simulation of land subsidence induced by groundwater overexploitation in Su-Xi-Chang area,China 总被引：2，自引：0，他引：2
Ji-Chun Wu Xiao-Qing Shi Shu-Jun Ye Yu-Qun Xue Yun Zhang Jun Yu 《Environmental Geology》2009,57(6):1409-1421
Su-Xi-Chang area is one of the typical regions in China which suffers from severe land subsidence. Various field monitoring
records were integrated to study the characteristics and mechanisms of land subsidence in this region. The development of
the land subsidence in this region shows a tight spatial and temporal correlation with the groundwater pumping. Based on the
analysis of the field data, it is found that the deformation patterns of the hydrogeologic units are greatly related to the
hydrogeologic properties and groundwater level variations. Some have an elastic behavior, others may have an elastic–plastic
rheology. Hence, a 3D finite element numerical model considering the rheological properties of the soil was developed to simulate
the groundwater level and land subsidence. Both hydraulic conductivity and specific storage were expected to vary with the
porosity during the process of consolidation. Multiscale finite element method (MsFEM) was applied to solve the model during
the period from 1996 to 2004. After calibrating the model with the observed groundwater level and subsidence data, the parameters
of the multi-layers system were estimated. The calibrated model outputs fit reasonably well with the observed data. Consequently
the model can be applied to predict groundwater level and land subsidence in future pumping scenarios. The model predictive
results show that land subsidence rate can be controlled and even rebound may occur after the implementation of the groundwater
exploitation prohibition.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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依托天津地区5个典型工程案例,对基坑降水引起的地面沉降规律进行了基本分析。由于基坑降水引起地面沉降的范围较远,往往能达到墙后5~10倍基坑开挖深度的距离,而实际基坑工程坑外沉降的测点往往布置在墙后1~4倍基坑开挖深度的距离,因此难以全面的获得不同类型基坑(如基坑深度不一)降水对地面沉降的影响范围。本文利用有限差分软件Modflow建立三维地下水渗流模型,并利用文化中心站的工程实测数据对该模型进行验证,最后利用该模型研究不同开挖深度的基坑(5~25m)降水对地面沉降的影响范围,并探讨5种不同止水帷幕截断方式的工况下坑内降水后坑外水位及地面沉降随时间发展关系。 相似文献
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长江三角洲地区深基坑降水复杂,且极易引起地面沉降地质灾害问题,传统的基于地下水动力学原理的解析解模型(Theis公式或Dupuit公式)已难以满足降水设计模拟计算的需要,尤其是无法预测降水引起的地面沉降问题,深基坑降水与地面沉降耦合模型将地下水渗流模型和土体应力-应变模型耦合起来,可根据基坑地下水位的控制要求,同时模拟计算出降水井的布局、各井的开采量和地面沉降量。据此确定出的基坑降水方案既能满足地下水位的控制要求,又能对降水引起的地面沉降进行最优化控制。 相似文献
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Jichun Wu Xiaoqing Shi Yuqun Xue Yun Zhang Zixin Wei Jun Yu 《Environmental Geology》2008,55(8):1725-1735
Land subsidence in China occurs predominantly in 17 provinces (cities) situated in the eastern and middle regions of the country,
including Shanghai, Tianjin and Jiangsu, and Hebei provinces. It is primarily caused by groundwater overpumping. One of the
areas most severely affected by land subsidence is the Yangtze Delta, most of which consists of Shanghai City, the Su-Xi-Chang
area (Suzhou, Wuxi and Changzhou cities) of Jiangsu Province, and the Hang-Jia-Hu area (Hangzhou, Jiaxing and Huzhou cities)
of Zhejiang Province. The excessive exploitation of groundwater forms in a large regional cone of depression and, consequently,
land subsidence is also regional, currently centered in the Shanghai and Su-Xi-Chang areas. In 2002, the maximum cumulative
subsidence of Shanghai, Su-Xi-Chang and Hang-Jia-Hu were 2.63 m, 2.00 and 1.06 m, respectively. The land subsidence area is
continuing to expand throughout the Yangtze Delta. To study the characteristics and the pattern of this land subsidence, the
government has implemented a monitoring system involving the placement of 37 groups of extensometers (layers marks) and drilling
of more than 1000 observation wells. These provide an invaluable historical record of deformation and pore water pressure
and facilitate studies on the special features of soil deformation when the groundwater level changes due to pumping. Several
measures have been taken in recent years to control the development of the land subsidence in the different areas; these include
groundwater injection, prohibition of pumping deep confined groundwater, and an adjustment of the pumping depth and magnitude
of the groundwater withdrawn. At present, although the subsidence area is still increasing slowly, the subsidence rate is
controlled. 相似文献