基岩浅埋的软土地基中基础处理方法的探讨

21世纪,城市化建设进程的加快使我国建筑行业取得了迅猛发展。但由于我国地理环境的复杂性,在我国珠江三角洲地区、渤海湾以及长江三角洲地区等地存在大面积的软土,有的地区在软土地基的基础上还存在基岩浅埋的状况,在这个对建筑质量要求日益提高的时代,对基岩浅埋的软土地基这一特殊地基进行基础处理从而加固地基,保证建筑质量成为建筑施工过程中至关重要的一个环节。本文从软土地基入手,分析了软土的特征以及软土地基进行基础处理的必要性,探讨了软土地基在基岩浅埋情况下的具体基础处理方法,以期能够确保基岩浅埋的软土地基质量,进而保证建筑物的质量,促进建筑行业的可持续发展。     

关于静载荷检测与实际沉降量关系问题的探讨

针对某建筑物沉降量较大的问题,通过分析工程地质勘察报告资料、工程的静载荷及低应变检测数据,对静载荷检测与实际沉降量的关系问题进行了探讨,对上海某些地区选择有软弱下卧层的浅部粉砂层为持力层时,静载荷试桩能否为设计提供可靠沉降数据的问题进行了思考,并提出建议.     

斜坡场地上几种典型建筑形式的抗震性能分析

介绍了斜坡场地上建筑物的特点，分析了基础兼挡土墙、吊脚柱形式、结构横向错层形式和多台阶结构横向错层形式建筑物的抗震能力，对斜坡场地上建筑物的抗震设计提出一些建议。     

浅论桩基础施工方法

建筑物的基础直接影响结构的安定性，基础方案的选型对建筑物的造价影响较大。就建筑物常见的几种基础，在施工过程中，可能遇到的问题从保证质量角度出发提出了自己的方法，对桩基础的设计、施工有一定的参考意义。     

台州某综合楼基础设计

通过对建筑物复杂场地的地质条件分析，对各种基础方案进行比较，确定用水泥搅拌桩复合地基作为基础方案。并对水泥搅拌桩复合地基的设计以及施工中的具体措施进行了详细阐述。     

金堆城揭顶硐室爆破群药包起爆时序的设计控制

主要论述了金堆城南露天揭顶硐室B级大爆破工程爆区微差起爆时序的设计控制,详述了装药量最大、设计施工管理难度最大的二爆区的设计思路、计算方法,复杂的爆破网络微差分布、起爆器材联接等内容,成功地爆破确保了工程的安全和施工进度,为工程的顺利竣工奠定了基础。     

严寒地区基础埋置深度问题的探讨

通过对基础埋深问题的探讨，提出了严寒地区在冻涨土及强冻涨土上建筑物基础埋深、防冻涨措施及注意事项。     

湿陷性黄土地基湿陷机理及地基处理方法

结合天津铁厂厂区湿陷性黄土的特点，进行了多种地基处理方案的探讨。提出了适合铁厂区湿陷性黄土场地建筑物基础干作业挖孔灌注桩基处理方案。对建筑物的地基设计、防水措施、结构措施提出了具体要求。     

地下水对建筑物地基的影响及防治措施分析

在建筑物地基基础设计中,结合岩土勘察资料,需要做好地下水对建筑物地基的防治处理工作。考虑到结构类型、材料情况和施工情况可知,如果地基内存在大量的地下水,则直接对建筑工程的正常使用和建筑物稳定性造成影响。本次研究中以地下水成因和不良后果作为基础,对如何进行防治进行分析。     

湖南省军区礼堂改造设计

根据新老建筑普遍存在的连接处理问题，分析新老建筑物基础连接时新建筑物基础对老建筑物基础的影响，提出解决问题的＝措施，减小新老建筑物基础的相互影响，通过处理基础落在防空洞抽风竖井上的特例。说明在城市建筑中常见的基础问题与处理解决方法。     

Reinforced Concrete Walls with Vulnerable Foundations

Moment capacities of shallow foundations are compared with those of reinforced concrete walls in order to determine the likelihood of exceeding the bearing capacity of the supporting soil in buildings subjected to strong ground motions. Recommendations are made regarding the appropriate modeling at the base of first-story walls in compliance with the moment-capacity axial load interaction of the supporting foundations.     

浅谈天铁高层住宅给排水设计

天津天铁冶金集团有限公司（以下称“天铁”）高层住宅是两栋地下1层,地上19层的高层民用建筑。文章分别从生活给水、消防给水、消防电梯井排水等方面介绍了给排水系统的设计依据和方案的确定。     

Capacity, Settlement, and Energy Dissipation of Shallow Footings Subjected to Rocking

The effectiveness of structural fuse mechanisms used to improve the performance of buildings during seismic loading depends on their capacity, ductility, energy dissipation, isolation, and self-centering characteristics. Although rocking shallow footings could also be designed to possess many of these desirable characteristics, current civil engineering practice often avoids nonlinear behavior of soil in design, due to the lack of confidence and knowledge about cyclic rocking. Several centrifuge experiments were conducted to study the rocking behavior of shallow footings, supported by sand and clay soil stratums, during slow lateral cyclic loading and dynamic shaking. The ratio of the footing area to the footing contact area required to support the applied vertical loads (A/Ac), related to the factor of safety with respect to vertical loading, is correlated with moment capacity, energy dissipation, and permanent settlement measured in centrifuge and 1 g model tests. Results show that a footing with large A/Ac ratio (about 10) possesses a moment capacity that is insensitive to soil properties, does not suffer large permanent settlements, has a self-centering characteristic associated with uplift and gap closure, and dissipates seismic energy that corresponds to about 20% damping ratio. Thus, there is promise to use rocking footings in place of, or in combination with, structural base isolation and energy dissipation devices to improve the performance of the structure during seismic loading.     

砖混结构房屋抗震设防策略分析

本文结合包头５．３地震震灾检查统计结果,论述砖混结构房屋的抗震减灾设防策略,由“抗”转变到“隔”的设防理论,讨论目前抗震设防中存在的问题,建议包头地区尽早推广应用基础隔震减震技术。     

Mechanisms of Seismically Induced Settlement of Buildings with Shallow Foundations on Liquefiable Soil

Seismically induced settlement of buildings with shallow foundations on liquefiable soils has resulted in significant damage in recent earthquakes. Engineers still largely estimate seismic building settlement using procedures developed to calculate postliquefaction reconsolidation settlement in the free-field. A series of centrifuge experiments involving buildings situated atop a layered soil deposit have been performed to identify the mechanisms involved in liquefaction-induced building settlement. Previous studies of this problem have identified important factors including shaking intensity, the liquefiable soil’s relative density and thickness, and the building’s weight and width. Centrifuge test results indicate that building settlement is not proportional to the thickness of the liquefiable layer and that most of this settlement occurs during earthquake strong shaking. Building-induced shear deformations combined with localized volumetric strains during partially drained cyclic loading are the dominant mechanisms. The development of high excess pore pressures, localized drainage in response to the high transient hydraulic gradients, and earthquake-induced ratcheting of the buildings into the softened soil are important effects that should be captured in design procedures that estimate liquefaction-induced building settlement.     

A comparison of IBC with 1997 UBC for modal response spectrum analysis in standard-occupancy buildings

This paper presents a comparison of the seismic forces generated from a Modal Response Spectrum Analysis (MRSA) by applying the provisions of two building codes, the 1997 Uniform Building Code (UBC) and the 2000-2009 International Building Code (IBC), to the most common ordinary residential buildings of standard occupancy. Considering IBC as the state of the art benchmark code, the primary concern is the safety of buildings designed using the UBC as compared to those designed using the IBC. A sample of four buildings with different layouts and heights was used for this comparison. Each of these buildings was assumed to be located at four different geographical sample locations arbitrarily selected to represent various earthquake zones on a seismic map of the USA, and was subjected to code-compliant response spectrum analyses for all sample locations and for five different soil types at each location. Response spectrum analysis was performed using the ETABS software package. For all the cases investigated, the UBC was found to be significantly more conservative than the IBC. The UBC design response spectra have higher spectral accelerations, and as a result, the response spectrum analysis provided a much higher base shear and moment in the structural members as compared to the IBC. The conclusion is that ordinary office and residential buildings designed using UBC 1997 are considered to be overdesigned, and therefore they are quite safe even according to the IBC provisions.     

Novel Method of Excavation

Construction in city center areas frequently requires below ground construction of underground car parks and basements immediately adjacent to existing buildings. When existing buildings are on shallow foundations, this form of construction poses considerable risks of litigation through damage to the existing buildings caused by ground movement. Consequently, construction costs of below ground construction in this type of environment are considerably higher than above ground construction costs. This paper presents a novel methodology for carrying out this form of construction and offering the advantages of considerably reduced risk of damage to adjacent buildings while still providing a cost-effective means of construction. The paper includes sufficient detail to allow this methodology to be adopted by other practitioners.     

等值反磁通瞬变电磁法在浅层地质结构探测的应用

在复杂地质结构区域实施的工程建设,受气象环境、水文环境、地形地貌、地质构造等因素影响,岩土极易发生变形,严重时可能因受力过大而开裂,进而导致地基和建筑物发生变形,给建筑物带来安全隐患。因此,工程建设实施前,必须要充分掌握浅层地质结构变化情况与规律,从而为工程设计与工程施工提供全面准确的参考依据。等值反磁通瞬变电磁法是地下浅层地质结构探测的关键技术手段之一,该法采用双线圈源建立一次场零磁通接收平面来消除一次场对接收线圈的影响,以观测到地下纯二次场响应,从而提高瞬变电磁探测的准确度,缩小浅层盲区,达到精准探测地下地质变化情况与规律的目的。该方法具有野外工作简便快捷、不受施工场地限制及抗干扰能力强等特点,并通过工程应用证实探测精度和结果的可靠性,在工程地质勘察领域具有很好的应用前景。     

IDA Comparison of IBC-Designed and DDD-Designed Six-Story Light-Frame Wood Buildings

The current International Building Code (IBC) allows wood-frame (i.e., light-frame wood) construction to be three stories high or four stories high if sprinklers are included in the design. Several jurisdictions within the United States have opted to allow four and five stories if sprinklers are present. This paper presents a comprehensive numerical analysis of a six-story wood-frame building designed on the basis of the 2006 IBC methodology and a building designed by using the direct-displacement design (DDD) approach. The objectives of the design methods are different and are explained herein. Incremental dynamic analysis (IDA) was used to numerically investigate the response of the buildings on the basis of two criteria: the peak interstory drift and the building’s base shear capacity. Gypsum wall board was included in both models, but exterior finishes (e.g., stucco) were not.     

Deformations during Cut-and-Cover Construction of MUNI Metro Turnback Project

Construction of the MUNI Metro Turnback project involved deep excavations in soft soils along the Embarcadero waterfront in downtown San Francisco, California. The excavations and shoring system were designed by the Engineer of Record to control ground deformations within specified limits in order to minimize the impacts of the deformations on a block of adjacent, settlement-sensitive buildings. The design included estimates of deformations caused by the excavations and other construction activities, evaluation of potential settlements of adjacent buildings, and structural evaluation of the response of the buildings to the estimated settlements. A comprehensive monitoring program combined with an instrumented test section, appropriate contingency measures, and construction controls were planned so as to allow early warning for appropriate response in the event that the deformations exceeded tolerable limits. This paper reviews the subsurface conditions, base stability analyses, and estimated deformations, describes the instrumentation program, and presents a comprehensive summary of the instrumentation measurements. It interprets the instrumentation measurements and draws conclusions regarding the general nature and magnitude of deformations and their impacts on adjacent structures.