水源井管上升及其防治对策

朔黄铁路肃宁北站的两口水源井成井至今其井管已上升了30cm，导致井台隆起和扬水管撅断，其他水源井也有类似现象发生。井管上升主要是由地下水过量开采、地面下沉引起的，故控制地下水开采量和进行地下水回灌是解决此问题的基本办法，而及时截断上升部分的井管、对井台进行合理改造以使其适应上升的井管则是被动处理办法。     

Subsidence of Building Foundation Resting Upon Liquefied Subsoil: Case Studies and Assessment

Subsidence and tilting of such structures as oil storage tanks and buildings which are not supported by deep foundations are an important kind of damage induced by seismic soil liquefaction. The present paper describes the results of case-history studies conducted in Dagupan City in the Philippines, where substantial damage occurred to buildings during an earthquake in 1990. Relationships of size and shape of buildings with the extent of subsidence were found, while a better correlation was detected by using soil stratification. This correlation appears helpful for quick assessment of the liquefaction-related risk of buildings. To investigate further the mechanism of subsidence, shaking table tests were conducted. Thereafter, an analytical method for predicting the subsidence of a building was developed by considering liquefied subsoil as a viscous fluid. It was accordingly possible to obtain reasonable matching between calculated and observed subsidence when the extent of damage was significant. On the other hand, a relatively poor matching when the damage extent was light suggests that liquefied sand was not so soft as supposed in the analysis. Combining the aforementioned correlation with stratification, this analytical measure will help carry out the risk assessment of liquefaction-prone buildings.     

抽水导致区域性地面沉降中的s–lnr线性关系

地下水开采造成区域性地面沉降及其带来的危害已成为全球性的地质灾害之一。对沉降区域内控制点的监测和预测是沉降研究的主要内容。基于弹性力学、有效应力原理和土体线弹性本构关系,在单井抽水造成地面沉降规律性研究的基础上,应用线性微分方程叠加原理论证了多井抽水时沉降–距离仍遵循s–lnr线性关系。通过国内外若干抽水导致的区域性地面沉降实例验证,虽然由于地层不均匀性和地质构造如断裂等影响,各地沉降漏斗并不规则,但都存在以上s–lnr的线性关系。文中揭示的区域性地面沉降中的s–lnr线性关系规律,可用于地面沉降研究中非监测点的沉降值推测和沉降趋势预测,具有重要应用价值。     

高填方强湿陷地段井桩下沉问题的探讨

 在湿陷性黄土地区，尤其是在经人为推山填沟整平的高填方地段，采用人工挖孔灌注桩基础(以下简称井桩)，往往会因各种原因导致井桩下沉引起建筑物发生变形事故。结合兰州市某经济开发区内几幢建筑物井桩基础下沉事故的典型实例，分析了该地段井桩下沉的原因，并对已采用的几种处理措施进行了探讨。     

基于地层损失的盾构沉降计算方法研究进展

近年来,越来越多的盾构隧道要穿越建筑密集区、重点建筑保护区和沉降敏感区,地面沉降的科学预测和合理控制成为亟待解决的问题。盾构法隧道施工诱发地面沉降的影响因素较多,但主要因素可归结为地层损失引起的地表移动。基于现有地层损失概念,按照经验-数学法和物理力学法体系论述了国内外盾构推进诱发地面沉降的研究进展,分析了现有研究方法的不足之处,对地层损失概念进行了重新界定,建立了基于沉降预测-施工控制的地层损失概念模型,提出了基于"地面沉降-地层损失-施工参数"联系通道的地面沉降控制流程。     

基于数值模拟的天津市地下水严重超采区演变分析

天津市是华北地区典型的水资源短缺城市,地下水的长期超采已引发地面沉降等环境问题。为科学分析地下水开采现状,并预测压采条件下的地下水严重超采区演化趋势,本文采用基于有限差分原理的MODFLOW软件,建立了天津市平原区地下水流动的三维非稳定流数值模型,经识别和校正过的模型能准确反映人工开采引起的各承压层地下水位波动。基于该...     

Development of building vulnerability functions in subsidence regions from empirical methods

The extraction of ores and minerals by underground mining often causes ground subsidence phenomena. In urban regions, these phenomena may induce small to severe damage to buildings. To evaluate this damage, several empirical and analytical methods have been developed in different countries. However, these methods are difficult to use and compare due to differences in the number of criteria used (from 1 to 12). Furthermore, the results provided by damage evaluation may be significantly different from one method to another. The present paper develops vulnerability functions based on a concept that has been applied in other areas, such as earthquake engineering, and that appears to be a more efficient way to assess building vulnerability in undermined cities. A methodology is described for calculating vulnerability functions in subsidence zones using empirical methods. The first part of the paper focuses on existing empirical methods for damage evaluation, and selected necessary improvements or modifications are justified. The second part focuses on the development of a building typology in subsidence zones and its application in the Lorraine region, where many villages are subject to subsidence problems due to iron-ore mining. The third section describes and discusses the adopted methodology for determining vulnerability and fragility functions or curves. Finally, vulnerability functions are tested and validated with a set of three subsidences that occurred in Lorraine between 1996 and 1999.     

盾构隧道下穿老旧建筑物群微沉降控制技术研究

中心城区盾构隧道下穿老旧建筑物的沉降控制是盾构施工的焦点问题。通常沉降控制方法是通过地表沉降监测数据,决定是否进行二次注浆,但地表及建筑物变形早已发生。为了弥补传统方法沉降处置滞后的不足,提出了"微沉降"施工控制技术,开发了壁后注浆雷达实时检测系统与自动化监测预警平台,在地表沉降发生之前及时注浆填充地层损失的空隙,防止地表沉降,保证老旧建筑物安全。济南轨道交通R3线王—裴区间隧道下穿越的老旧建筑物群,建造时间多为20世纪70—80年代,部分墙体风化严重,大大增加了地表沉降控制、建筑物保护难度。首先,利用三维有限元软件,对隧道下穿苏宁大楼和农业银行进行三维数值模拟,认为适当增加注浆压力可以有效减小地表沉降值,模拟结果与监测数据较为吻合。其次,为了掌握壁后注浆质量,控制隧道下穿化肥厂宿舍楼时的地表变形,开发了壁后注浆雷达实时检测技术,在衬砌拼装间隙检测注浆质量,动态调整注浆压力及注浆量,有效控制了地表沉降。同时,项目采用自动化监测和人工监测联合的监测方案,实时监测建筑及地表变形,并通过移动端手机应用实时掌握变形情况,可及时采取措施。利用雷达实时检测结果与地表监测结果,地上地下联动,地表沉降被控制在5 mm之内,最终基本实现了"微沉降"的目标,建筑物得到了良好的保护。     

南阳膨胀土地区房屋开裂的原因和治理对策

1977~1978年南阳出现严重干旱,南阳西郊膨胀土地区发生大规模房屋开裂损坏。介绍了房屋开裂损坏的特征,分析了导致房屋损坏的原因,提出了预防和整治措施。     

煤矿开采沉陷区地表与建筑物变形探讨

在分析采空区上部岩体结构破坏特征、地表移动变形及其对上部建筑物影响的基础上,提出了有效吸收抵抗采空沉陷区地表不均匀沉降及建筑物结构抗变形的设计思路,简要阐述了采空区建筑物地基与基础协同工作,并且对上部结构的构造措施提出相关建议。     

某工程地下水对筏板基础的作用及其灾害机理

地下空间的开发因地下水的影响而产生了一系列岩土工程问题,特别是地下水对地下建(构)筑物的筏板基础的浮托作用,将引起基础不均匀变形和破裂。本文针对某工程地下室筏板基础不均匀上浮事故,通过采用探地雷达、测量及监测手段,结合水文地质和工程地质分析,探讨了地下水对建筑物筏板基础的作用及其灾害机理。研究结果表明,造成筏板基础上浮的主要原因是地基中存在两层复杂的上层滞水,由于没有进行有效的地下水控制和采用合理的施工措施,导致地下水灾害发生。工程采用了降水处理措施,起到了一定的治理效果。     

Evaluation on the behavior and contributing factors of subsidence in the intersection area of Expwy 78 and Taiwan High Speed Rail based on in situ monitoring and numerical simulations

This paper discusses the behavior and contributing factors of land subsidence in the intersection area of Expressway (Expwy) 78 and Taiwan High Speed Rail (THSR), located on Choshui River alluvial fan-delta (CRAFD) to the midwest of Taiwan. Since the CRAFD has been suffering a long-time problem of land subsidence, the transportation safety of THSR and Expwy 78 thus has become a major concern. The subsidence of CRAFD can be attributed to several factors, including overexploitation of groundwaters for area development. However, additional loadings of Expwy 78 and THSR structures would appear to deteriorate the problem. It would be of interest to know the influence of various factors on subsidence of the study area where the subsidence has now become most serious along the entire THSR route. It would also be advisable to provide information on the potential effects of subsidence on the integrity of THSR structure. With these aims, we perform analyses on the subsidence of the area based on 8-year on-site monitoring and numerical simulations. Results indicate, in a period started approximately from Expwy 78 construction, the average subsiding rate would be 10.53 cm/year, with relative contributions of 14.1%, 55.2%, 11.8%, 11.6%, and 7.3%, respectively, by the factors of soil creeping, previous overpumping, groundwater fluctuations, and loadings of Expwy 78 and THSR. We also estimate 23% and 77% of total subsidence occurred as the compressions of soils within and beyond the installation depth of THSR piles, which might impair pile bearing capacity and vertical alignment, respectively, of THSR.

     

采动建筑物在沉陷区内位置的GIS拓扑算法

地下资源开采常常引起周围环境的负面效应,造成地面建筑物、公用地下管线和各种地下设施以及城市道路的路基、路面、铁路等不同程度的损害,利用GIS可以有效地把这种负面效应和损害可视化.在可视化过程中,经常要判断不同地理要素的空间位置关系.基于GIS所特有的拓扑关系特性,把开采沉陷区域的建筑物和沉陷等值线空间位置关系抽象成理论模型,并进一步探讨了点与曲线环关系算法以及利用现有GIS软件如何来实现拓扑关系的方法.通过这种可视化,可以为决策提供可靠的信息依据,从而更好地为工程服务.     

基于双态泊松模型的地震危险性分析方法

目前我国通常采用的地震危险性分析方法是基于地震的发生属于泊松模型,但实际上地震发生的特点与泊松模型的假设有一定差异。本文根据实际地震发生的特点,总结出地震发生的双态泊松模型,把地震活动期分为相对平静期和相对活动期,并且这两个活动期分别符合泊松模型。在此基础上,对地震危险性的分析方法进行了探讨。     

基于结构动力可靠性的地震保险费率厘定方法

通过对动力作用下结构物的动力可靠性分析,在假定地震损失满足β分布的情况下,本文推导了在只考虑直接经济损失情况下的地震保险费用计算的相关公式。该计算方法简单明了,可以为政府和保险业务部门提高巨灾保险精算方法提供参考与支持。     

Deterioration of a Tunisian coastal aquifer due to agricultural activities and possible approaches for better water management

The purpose of this study is to provide a better understanding of the impact of agricultural activities on groundwater quality in a semi‐arid coastal environment (Korba, Tunisia). Impacts have been assessed through groundwater samples that were analysed for a range of chemical and biological parameters. Results indicate that groundwater overexploitation for irrigation and fertiliser use have affected the quality of the groundwater not only by direct contamination but also seawater intrusion. The implementation of appropriate regulatory and economic instruments to foster sustainable practices in the agricultural sector have been analysed within the framework of the EC (European Community) FP6 (funding program 6) INECO (Institutional and Economic Instruments for Sustainable Water Management in the Mediterranean Region) Project. Through stakeholder involvement processes, the project analysed issues relating to the regulation and control of groundwater abstractions, the promotion of wastewater reuse, efficiency improvements in irrigation water use, as well as instruments to strengthen the socioeconomic and institutional environment towards better managing and conserving available groundwater resources.     

An analysis of the resilience capacity of soils in North China: a study on land subsidence treatment

In order to study treatment measures for the land subsidence caused by deep groundwater overexploitation, we conducted soil compression and rebound tests to analyze the unloading and rebound regularity of deep soil on the fringes of three typical land subsidence regions in North China. Using fuzzy mathematics, we specifically explored the main factors influencing the soil mass unloading resiliency. The results indicated that the ratio between the unloading resilience volume and the loading deformation volume of soil mass in the study areas (referred to as the resilience capacity of soil mass) is between 1.6 and 37.6 %, with an average of 14.7 %. In other words, only about 14.7 % of the land subsidence deformation in the study areas can be restored. The soil masses with different properties in North China all possess elastoplasticity and the resilience capacities of soil can vary from area to area. The sandy soil is not completely elastic but has a certain degree of plasticity; the resilience capacity of soil mass is not a constant, but rather, a variable that changes with the rebound stress value. When the rebounding stress value is determined, the resilience capacity under a smaller unloading stress is larger than that under a larger unloading stress, which demonstrates that earlier land subsidence treatment can result in better effects. Meanwhile, the resilience capacity of soil mass is also enhanced with the increase of rebounding stress, indicating that the closer to the original groundwater level the restored groundwater is, the better the resilience capacity will be. After repeated loading and unloading tests have been conducted under the same stress, the resilience capacity of soil mass will, in most cases, increase to a certain extent. These results can be quite conducive to the treatment of deep groundwater exploitation-induced disasters such as land subsidence.     

上海某枢纽基坑工程浅层承压水回灌试验分析

随着上海城市建设进程的不断推进,深大基坑大量涌现,同时因城市立体空间设施的密集化,使得基坑周边环境趋于复杂,在此背景下因浅层承压水降水而引起的工程性地面沉降事故不断发生,给社会带来了巨大的经济损失。地下水人工回灌是控制因降水引起的工程性地面沉降的方法之一,目前地下水人工回灌系统主要应用于深层承压水的回灌。本文通过上海某地第一承压含水层的回灌试验,研究分析了浅层承压含水层回灌井的结构、回灌过程中地下水的流态变化规律、水土应力变化及对控制地面沉降作用的效率,证明了浅层承压水回灌在基坑环境保护中的可行性。试验研究对基坑建设中的地下水浅层承压水回灌系统的设计和施工有重要的指导意义。     

Sand creep as a factor in land subsidence during groundwater level recovery in the southern Yangtze River delta, China

A number of areas worldwide are suffering from the land subsidence, including the southern Yangtze River delta, the most developed area in China. Land subsidence is mainly induced by excessive groundwater pumping and has caused numerous problems, for example, flooding, structural cracking, and ground fissuring. Although several countermeasures have been adopted to mitigate the land subsidence problem in the southern Yangtze River delta, commonly using groundwater recharge, land subsidence is still developing even when groundwater levels are rising. The observation data of land subsidence in each stratum show that the deformation of the pumped aquifer is even greater than that in the adjacent aquitards when groundwater levels are recovering. Laboratory test results on the aquifer sand in Shanghai and Changzhou (two cities in the studied area, which have the most sufficient observation data about the land subsidence and groundwater level developing with time) proved that sand creep deformation is significant and is partially responsible for the land subsidence without groundwater level drawdown. Considering the difficulty and cost of collecting borehole samples from deep pumped aquifers to obtain the essential parameters for the existing sand creep calculation models, a simplified method was then proposed to calculate the sand creep deformation in the pumped aquifer. The relationship between the sand creep rate and the time can be recognized as linear using double logarithmic coordinates and the slope can be assumed to be one. In the proposed method, the laboratory test data are not necessary. Finally, case histories from Shanghai and Changzhou were used to verify the effectiveness of the proposed method.     

Erdbebenrisiko‐Kartierung für Deutschland

Earthquake Risk Assessing and Mapping for Germany The aim of this study is to assess and map the seismic risk for Germany. There are several earthquake prone regions in the country which have produced ML magnitudes above 6 corresponding to ground shaking intensity VIII (EMS‐98). Combined with the fact that some of these earthquake prone areas are densely populated and highly industrialized and where therefore the hazard coincides with high concentration of exposed assets, the damaging implications from earthquakes must be taken seriously. In this study a methodology is presented and pursued to calculate the seismic risk from intensity based probabilistic seismic hazard, vulnerability composition models, which are based on the distribution of residential buildings of various structural types in representative communities and distribution of assets in terms of replacement costs for residential buildings, which are estimated for all communities of the country. The estimates of risk are treated as primary economic losses due to structural damage to residential buildings. The obtained results are presented as maps of the damage and risk distributions. For a probability level of 90% non‐exceedence in 50 years (corresponding to a mean return period of 475 years) the mean damage ratio is up to 20% and the risk up to hundreds of millions of euro in the most endangered communities. The developed models have been validated with observed data from several damaging earthquakes in Germany and the nearby area in the past 30 years.