第一节 变形观测概述
　　 一、变形观测的概念
　　 变形是指被监测对象(变形体)的空间位置随时间发生变化的形态和特征。变形观测是利用各种测量方法和仪器来测定、查明建筑物(构)及其地基在建(构)筑物荷重、外力作用和环境变化的情况下随时间而产生变形的测量工作。
　　 无沦是民用建筑还是工业建筑(包括它们的地基、基础)都要求其坚固稳定，从破土动工到竣工使用，都应达到设计质量标准，以确保安全，延长使用期限。随着现代化建设的需要，许多具有大型大跨度、连续性自动化、精密复杂机械设备的厂房及高耸建筑物日益增多，对于它们的工程质量和安全可靠程度进行变形观测就显得尤为重要。
　　 建(构)筑物由于受到各种条件和要素的影响，使建筑物本身及其设备在运营过程中必然会发生变形。这种变形表现为使建(构)筑物整体或局部发生沉陷、倾斜、位移、扭曲、裂缝等。如果这种变形在允许限差之内，则认为是正常现象，否则，就会导致建(构)筑物的变形或开裂，影响建(构)筑物的正常使用，严重的会危及建(构)筑物的安全。
　　 二、引起建(构)筑物变形的原因
　　 引起建(构)筑物变形的因素很多，归纳起来其原因主要有以下儿个方面。
　　 (1)自然条件及其变化。因为建(构)筑物的自重与荷载都是由地基承受的，而地基则取决于工程地质、水文地质、土壤岩石结构的物理化学性质等。因此，当土质与荷重不同，加上地下水的变化，就会产生不稳定状态，当然也包括自然灾害如地震、飓风、滑坡、洪水等影响，使建(构)筑物发生不均匀沉陷或形变，甚至遭到破坏。
　　 (2)与建(构)筑物本身相关的原因。由于建(构)筑物本身的荷重、结构、材料、形式及机械运行中的振动作用而产生的变形。
　　 (3)由于勘测、设计、施工以及运营管理等方面工作不够合理引起的建(构)筑物的变形。
三、建筑物变形观测的目的
　　 通过变形观测可以取得第一手资料，积累实践性经验。通过监测建(构)筑物的状态变化和工作情况，以便在发生不正常情况时，及时分析原因，采取措施加固，合理使用，保证安全，防止事故发生。变形观测实际上也是对设计、施工的一种检验，对于采用新的结构、新的施工方法、新的工艺，通过变形观测来验证其效果，以便于改进和提高设计、施工质量，保证运营安全、经济合理，也可进一步作为科研的依据。具体目的如下：
　　 (1)安全保证。通过重复或持续观测，发现异常变化，以便及时采取措施，防止事故发生。
　　 (2)积累资料。检验设计是否合理，作为以后修改设计方法、制定设汁规范的依据。
　　 (3)为科学试验服务。变形观测是监测重要建(构)筑物在各种应力作用下是否安全的重要手段，也是验证设计理论和检验施工质量的重要依据。丁业与民用建(构)筑物、建筑场地、地基基础等，为对其维护及保证其使用安全，常要进行变形观测。
　　 四、变形观测的内容
　　 变形观测的内容，应根据建(构)筑物的性质与地基情况而定，要求针对性强，重点明确，考虑全面，正确反映出建(构)筑物的变化情况，以达到监测建(构)筑物安全运营，了解其变形规律的目的。归纳起来，主要观测内容有沉降观测、位移观测、倾斜观测、裂缝观测和挠度观测等。
　　 五、变形观测的特点
　　 与一般的测量丁作相比，变形观测有以下特点：精度要求高、需要重复观测、观测时间长、数据处理方法严密等。
　　 对于工程的安全来说，监测是基础，分析是手段，预报是目的。同时，变形观测属于多学科的交叉领域，涉及测绘、工程、地质、水文、应用数学、系统沦和控制论等学科的知识。
　　 六，变形测量点的分类
　　 1．变形观测点
　　 变形观测点即变形点，是固定在拟观测建(构)筑物上的照准标志，点位要设立在能准确反映变形体变形特征的位置上。应牢固地与建(构)筑物结合在一起，并尽量保证在整个沉降观测期间不受损坏。观测点的数量和位置，应能全面反映建(构)筑物的变形情况，尽量布置在变形变化可能显著的地方，如伸缩缝两侧、地质条件或基础深度改变处、建(构)筑物荷载变化部位、平面形状改变处、建(构)筑物四角或外沿墙每10-15m处、具有代表性承重支柱和基础上，均应设置变形点。
　　 2．基准点
　　 观测变形观测点的变化情况，必须要有一些相对固定不动的点作为基准，即基准点。基准点点位要设立在变形区以外的稳定地区，每个工程至少应有3个基准点。
　　 为了达到基准点稳定，一是远离要监测的建(构)筑物；二是深埋。
　　 3．工作基点
　　 通视条件较好时，可不设立工作基点，直接在基准点上测定变形点。一般为了观测方便及提高观测精度，基准点距离变形观测点远时。可在建(构)筑物附近布设工作基点，即作为直接测量点。
 

Section deformation observation Overview
First, the concept of deformation observed
Deformation is being monitored objects (deformed) spatial location changes with time the shape and characteristics. Deformation observation is the use of a variety of measurement methods and instruments to measure, identify the building (structure) and its foundation in the building (structure) construction material loading, the external force and environmental changes over time, circumstances arising from the deformation measurements.
No perish is a civil or industrial buildings (including their foundations, infrastructure) are requested its strong and stable, from the groundbreaking to the completion of the use, should meet the design quality standards to ensure safety, extend the period of use. With the modernization drive, and many with large large-span, continuous automation and sophisticated machinery and equipment of the plant and growing number of high-rise buildings, for their project quality, safety and reliability degree of deformation observation becomes particularly important.
Building (structure) building materials due to various conditions and elements, making the building itself and its equipment in operation is bound to occur during the deformation. In order to build the performance of this deformation (structures) building materials as a whole or partial subsidence occurs, tilt, displacement, distortion, cracks and so on. If this deformation is allowed within the limit of difference, then that is a normal phenomenon, otherwise it will lead to building (structure) building material deformation or cracking, affecting building (structure) of the normal use of building materials, serious would endanger the construction of ( structures) building material security.
2, causing building (structure) deformation of the reasons for building materials
Rise building (structure) building material deformation of many factors, summed up several reasons for the following main aspects.
(1) natural conditions and its changes. That the construction (structure) building material of the weight and load borne by the foundation, while the foundation will depend on engineering geology, hydrogeology, soil, rock structure, physical and chemical properties. Therefore, when the soil and load differences, coupled with changes in groundwater, it will produce an unstable state, of course, including natural disasters such as earthquakes, hurricanes, landslides, floods, etc., making the building (structure) building materials of uneven subsidence, or deformation, or even destroyed.
(2) Construction (structures) building materials per se causes. Because the (structure) building material itself load, structure, materials, form and mechanical vibrations in the operation of the role of the deformation arising.
(3) The investigation, design, construction and operational management aspects of the work is not reasonable due to construction (structure) building material deformation. 

Deformation can be obtained by observing first-hand information, and accumulated practical experience. By monitoring the building (structure) building materials and work conditions of the state change so that in the event of abnormal situations, timely analysis of the causes and take measures to reinforce the rational use, ensure safety and prevent accidents. Deformation observation actually design and construction of a test for the introduction of new structures, new construction methods, new technology, through the deformation of observations to validate its effectiveness in order to refine and improve the design, construction quality, ensure operational safety , economic rationality, but also serve to further scientific basis. Specific objectives are as follows:
(1) security guarantees. By repeating or continuous observation of abnormal changes in order to take timely measures to prevent accidents.
(2) accumulation of information. Check whether the design is reasonable, as the subsequent modification of the design method to develop a basis for specification-based sauce.
(3) for scientific testing services. Deformation observation is to monitor key building (structures) in a variety of building materials under stress is an important means of security, but also verify the design theory and an important basis for testing the quality of construction. Ding industry and civil construction (structures) building materials, construction sites, ground-based, etc. for their maintenance and ensure the safety of their use, and often observed to be deformed.
Fourth, the contents of deformation observed
Deformation of the contents of observation should be based on building (structure) the nature and foundation of building material circumstances, and require targeted, focused, consider a full and correctly reflects the building (structure) changes in building materials in order to achieve the monitoring of construction ( structures) the safe operation of building materials to understand the purpose of the laws of their deformation. To sum up, the main contents of the settlement observation observation, displacement observation, tilt observation, observation and crack deflection observations.
5, deformation characteristics of the observed
With the measurement of D as compared to the general, deformation observation has the following characteristics: high precision, need to repeat observations are a long time, data processing method rigor.
For the safety of the works, the monitoring is based on analysis is a means of forecasting is the goal. Meanwhile, the deformation observation of cross-cutting areas are multidisciplinary, involving mapping, engineering, geology, hydrology, applied mathematics, systems and cybernetics perish the disciplines of knowledge.
6, deformation measurement points classification
1. Deformation observation points
Deformation observation points that deformation point is fixed to be observed in the construction of (structures) Buildings awarded on the signs, points are to be set up where it can accurately reflect the deformation characteristics of deformed position. Shall be firmly with the building (structure) building materials together, and try to ensure that the entire observation period of the settlement are not damaged. The number and location of observation points should be able to fully reflect the building (structure) of the deformation of building materials, as arranged in the deformation may be significant changes in places, such as expansion joints on both sides of the geological conditions or changes in the basis of the depth of Office building (structure) building material changes in load area, flat shape, to change the Department, the building (structure) Buildings corners or outside along the wall at every 10-15m, with representation based on the load-bearing pillar and should be set the transformation point.
2. Benchmark
Observing the changes in deformation observation points, there must be some relatively stationary point as a benchmark, or reference point. Benchmark little bit to be set up outside the deformation zone of stability in the region, each project at least three reference points.
In order to achieve a stable reference point, one away from the building to be monitored (structure) building materials; second is buried.
3. Working point
Pass as the conditions are favorable, may from time to set up a working basis points, measured directly on the reference point on the transformation point. In order to facilitate and enhance the general observation observation precision, reference points far from the deformation when the observation points. May be under construction (structures) near the emplacement of the work of building materials basis points, or as a direct measurement points.