Close-range Photogrammetric Techniques Research Articles

Thermal Deformation Measurement of the Surface Shape of a Satellite Antenna Using High-Accuracy Close-Range Photogrammetry.

To determine both the size of a satellite antenna and the thermal deformation of its surface shape, a novel high-accuracy close-range photogrammetric technique is used in this study. The method is also applied to assess the performance of the antenna in orbit. The measurement principle and solution method of close-range photogrammetry were thoroughly investigated, and a detailed measurement test scheme was developed. A thermal deformation measurement of the surface shape of a satellite antenna was then carried out. The results show that the measurement error using close-range photogrammetry was smaller than 0.04 mm, which meets the accuracy requirement. Thanks to the high accuracy, it was discovered that both the surface shape and the rib precision of the satellite antenna deteriorate with decreasing temperature. The accuracy of the surface shape and ribs was lowest when the temperature node was -60 °C. The maximum root mean square errors (RMSEs) reached 0.878 mm and 0.761 mm, respectively. This indicates that the surface shape deformation error of the antenna caused by high and low temperatures is relatively high. However, the requirement for the technical design index (RMSE ≤ 1 mm for the surface shape accuracy of the antenna) is still met. Furthermore, for temperature differences of 40 °C and 80 °C, the measured RMSEs for the surface shape deformation were 0.216 mm and 0.411 mm, respectively. Overall, the technical design indicators (RMSE ≤ 0.3 mm and RMSE ≤ 0.5 mm, respectively) for the surface shape deformation of the antennas are met.

Erosion Monitoring in Benggang Based on Control-Free Images and Nap-of-the-Object Photogrammetry Techniques

Erosion Monitoring in Benggang Based on Control-Free Images and Nap-of-the-Object Photogrammetry Techniques

INTEGRATION OF TERRESTRIAL LASER SCANNING AND SMARTPHONE LIDAR: THE CASE STUDY OF LIDZBARK CASTLE

Abstract. In many cases, archaeological research allows to explain the history and evolution of heritage buildings. To support these studies, the availability of reliable 3D representations of such buildings has already been shown to be of remarkable importance. Thanks to the development of Terrestrial Laser Scanning (TLS) and close-range photogrammetric techniques, the generation of such 3D representations by means of remote sensing techniques has become quite common nowadays. While TLS can still be considered as the state-of-the-art method for generating accurate building geometric models, acquisition methods based on the use of mobile devices is becoming a quite attractive solution in order to speed up the survey while also enabling an easier data acquisition on certain narrow places. Despite a plethora of mobile mapping tools is currently available on the market, smartphones are clearly the most widely used smart mobile device in the world, being an ideal solution in terms of usability, portability, and spread. Motivated by this observation and by the recent availability of smartphones provided with Light Detection and Ranging (LiDAR) sensors, this paper aims at investigating the effectiveness of the integration of traditional TLS with smartphone LiDAR on the survey of the castle in Lidzbark Warminski, which dates back to the mid-fourteenth century. TLS, with the scanner set on a standard tripod, was used to scan easily accessible places. TLS mounted on a dedicated tripod, patented by the co-authors of the project was used for less easy-to-reach places. Finally, smartphone LiDAR enabled 3D data acquisition on very hard-to-reach locations, e.g. excavation areas. The model obtained by integrating the data acquired by all the considered methods allowed to properly describe all the area of interest of the castle, being usable for the technical documentation of such historic building. The obtained model significantly advanced the state of knowledge about the castle in Lidzbark Warminski. As a result of the work, many traces of the history of the complex were discovered, proving its gradual evolution.

The possibility of using close-range photogrammetry in the inventory of historic complex basements - case study

In the community, historical objects play the role of witness to past history. Due to that fact, it is necessary to preserve and reconstruct cultural heritage objects and sites for the future generation. Image-based photogrammetric methods have been widely applied for this purpose for many years. Nowadays, Terrestrial Laser Scanning (TLS; range-based method), due to its advantages such as speed of data acquisition, high accuracy and independence from light conditions, is increasingly used in the inventory of complex historic buildings. Despite this, the development of modern image processing methods, i.e. Structure-from-Motion (SfM) and Multi-View Stereo (MVS), has meant that close-range photogrammetric techniques are still competitive with TLS. The article aimed to present the possibility of using close-range photogrammetry to inventory historic complex basements. Laser scanning was performed as part of the measurements (with a Z+F 5006h scanner), and a series of close-range images were taken with a full-frame non-metric Canon 5D Mark II camera. Based on the combined SfM and MVS methods, a dense point cloud was generated, which in a subsequent data processing step served as the basis for generating 3D models and cross-sections. To assess the quality of the generated documentation, the TLS data were used as ground-truth data, and the shape and cross-section mapping quality was compared. It is evident from the investment presented that the use of close-range photogrammetry methods makes it possible to generate documentation that meets the requirements of architectural studies and similar shape accuracy for historic complex basements.

3D MODELLING METHOD OF HIGH ABOVE GROUND ROCK ART PAINTING USING MULTISPECTRAL CAMERA

Abstract. This paper presents a developed methodology of 3D modelling of rock art painting located at high above shelter floor based on close-range photogrammetric technique. Instead of using elevated devices to reach inaccessible paintings due to high elevation, the developed method proposed a simple technique. The camera was mounted on an expandable pole to acquire the panel with normal and tilted camera settings. Due to inaccessibility to place the control point marker on the panel surface, the distribution of photo control was positioned below the panel. Based on the configuration, the image of the panel was acquired using the low-spatial resolution multispectral camera in a two elevated strips position that imitates the aerial photogrammetry flight line. The camera was set parallely to the painting panel on both strips, with additional tilted geometry included at the upper strip of the camera block. The acquired multispectral images were then processed using commercial SfM photogrammetry software to generate a 3D point cloud. The accuracy of constructed point cloud was then analysed by comparing it with the point cloud generated using a terrestrial laser scanner (TLS). The result has shown that the multispectral 3D point cloud has a small deviation against the TLS point cloud. The mean deviation was -0.43mm, indicating a slight downscaled on the multispectral point cloud.

Deep Foundation Testing using Immunity-based Displacement Measurement in Successive-Sparse Images

This paper presents a new immunity-based approach to measure the displacement of nodes (or points of interest) in successive-yetsparse images, in order to measure the settlement of deep-foundations under heavy loads. It is developed as a close-range photogrammetric technique to search the nodes, similar to immune-cells searching bacteria in their vicinity. The immunological concepts of chemotaxis, biased random walk, diffusion and inflammation are implemented herein to accomplish the task. The technique greatly reduces the errors and is also validated on site of a mega project to record the settlements in deep foundations. The accuracy levels are found to be conforming to ASTM’s standards for static load testing, including both compression and lateral-load tests. Unlike other techniques, such as particle image velocimetry, this approach is able to handle successive-images with varying ΔT between them. Furthermore, the technique is completely autonomous and does not require any embedded instrumentation.

Development of Web-Based GIS for the Cultural Heritage of Safranbolu, Turkey

Heritage and culture are two important components for the historical sites all over the world. Furthermore, cultural heritage is an important term regarding the question of how such historical sites may be valued. Cultural heritage areas of countries have great significance in terms of history, tourism, recognition of the country and economy. Not only having historical heritage is important, but also it is very important to protect and revitalize these sites. For this purpose, UNESCO lists the heritage sites with the aim of helping the countries. In this regard, Turkey has nine historical premises under protection by UNESCO, and one of them is the Safranbolu historical city. The main goal of this study is the 3D modelling of all historical constructions as similar to real status in Safranbolu historical city and the creation of an information system. Firstly, a GIS-based management system has been developed through cultural heritage documentation for this historical city. All registered historical buildings and 3D models of selected buildings that are produced using close range photogrammetric technique are assigned within the database. Data coming from different sources related to these registered buildings were published and distributed via internet by a web-based information system designed specifically for this study.

THE MEASUREMENT OF FULL SCALE STRUCTURAL BEAM-COLUMN CONNECTION DEFORMATION USING DIGITAL CLOSE RANGE PHOTOGRAMMETRY TECHNIQUE

Measurement and monitoring of structural components such as beams and columns under loading are important in structural analysis and design assessment. Presently, the assessment on structural components on deformation or displacement measurement is carried out through LVDTs or dial gauges. The LVDTs or dial gauges were installed in contact with the structural components, also known as contact method. However, present contact method is subjected to some limitations such as s displacement points of measurement are highly depend on the position of LVDTs available, reliability of LVDTs and dial gauges to measure during the experiments due to possibility of damage sensors and consumption of time on the installation the sensors. Due to the limitations of contact method, this study demonstrates the use of a noncontact method using digital close range photogrammetry technique to measure the deformational behaviour of full-scale structural beams and columns. In this study, a full-scale load tests on structural components were performed under laboratory conditions. A series of digital images of the structural beams and columns under various loads were captured using Nikon DSLR cameras. The digital images then processed and analyzed using digital close range photogrammetric technique to measure and extract the magnitude of the structural beam and column displacements. The deformation and displacement of beam and columns have been validated by comparing the photogrammetric outputs against the results obtained from the LVDTs. The statistical analysis shows the differences obtained between the photogrammetric technique and contact method used were not significant.

3D non-invasive inspection of the skin lesions by close-range and low-cost photogrammetric techniques

In dermatology, one of the most common causes of skin abnormality is an unusual change in skin lesion structure which may exhibit very subtle physical deformation of its 3D shape. However the geometrical sensitivity of current cost-effective inspection and measurement methods may not be sufficient to detect such small progressive changes in skin lesion structure at micro-scale. Our proposed method could provide a low-cost, non-invasive solution by a compact system solution to overcome these shortcomings by using close-range photogrammetric imaging techniques to build a 3D surface model for a continuous observation of subtle changes in skin lesions and other features.

Studying the rate of corrosion of the bottom of a jet loop reactor using digital close-range photogrammetric techniques

The current task intends to research the impact of various operating and geometrical parameters on the corrosion rate of a jet loop reactor bottom. Photogrammetry is a recent surveying method that has been used to picture and measure the corrosion rate. Henceforth, the three dimensional model of the affected regions of the reactor which are under investigation have been formed by one of the photogrammetric methods. The physical properties of the solution (viscosity and density), the nozzle height, the nozzle diameter and the flow rate of circulation are the variable that are being studied.A dimensionless equation was developed from the experimental data, which will be a useful tool for prediction of the corrosion rate at the jet loop reactor bottom within the present range of operating conditions.

실내모형시험을 통한 사질토 지반에서 군말뚝과 터널의 수직 이격거리에 따른 하중분포 및 지반거동 분석

도심지에서의 터널굴착은 상부구조물과의 상호거동에 대한 이해가 필수적이다. 도심지에 사용중인 대부분의 구조물은 말뚝기초로 상부의 하중을 지지하고 있어, 터널 굴착 시 반드시 영향을 받는다. 따라서 본 연구에서는 실내모형시험을 통해 기존의 군말뚝 기초 하부 터널굴착에 따른 축력 분포와 지반의 거동을 분석하였다. 말뚝 기초는 2, 3 열 말뚝으로 가정되었으며, 말뚝 선단부와 터널 천단부의 이격거리는 터널직경에 대한 일반화를 위해 터널 직경(D) 대비 0.5D, 1.0D 그리고 1.5D로 고려되었다. 지반은 약 30%의 상대밀도(Dr)를 가지는 느슨한 사질토로 형성되었으며, 말뚝의 축력 분포를 측정하기 위해 말뚝에 변형률게이지(strain gauge)를 부착하였다. 또한, 이격거리에 따른 군말뚝의 침하와 인접지반의 침하를 변위센서(linear variable differential transformer; LVDT)와 다이얼게이지(dial gauge)를 통해 측정였으며, 터널굴착에 따른 지중의 변형을 근거리사진계측기법(close range photogrammetric technique)을 통해 측정하였다. 수치 해석을 통해 실내모형시험 및 근거리사진계측 결과와 비교 분석하였다. 본 연구에서는 체적손실율(volume loss; <TEX>$V_L$</TEX>) 개념을 이용하여 터널굴착을 모사하였으며, 1.5%로 적용되었다. 연구결과, 이격거리가 멀어질수록 말뚝의 축력감소는 작게 나타났으며, 침하량은 모두 유사한 경향을 나타내었다. 특히, 말뚝 선단부와 터널 천단부의 이격거리가 0.5D에서 1.0D로 증가할 때 축력과 침하량의 가장 큰 감소율이 가장 큰 것으로 나타났다. Tunnelling in urban areas, it is essential to understand existing structure-tunnel interactive behavior. Serviced structures in the city are supported by pile foundation, since they are certainly effected due to tunnelling. In this research, thus, pile load distribution and ground behavior due to tunnelling below grouped pile were investigated using laboratory model test. Grouped pile foundations were considered as 2, 3 row pile and offsets (between pile tip and tunnel crown: 0.5D, 1.0D and 1.5D for generalization to tunnel diameter, D means tunnel diameter). Soil in the tank for laboratory model test was formed by loose sand (relative density: Dr = 30%) and strain gauges were attached to the pile inner shaft to estimate distribution of axial force. Also, settlements of grouped pile and adjacent ground surface depending on the offsets were measured by LVDT and dial gauge, respectively. Tunnelling-induced deformation of underground was measured by close range photogrammetric technique. Numerical analysis was conducted to analyze and compare with results from laboratory model test and close range photogrammetry. For expression of tunnel excavation, the concept of volume loss was applied in this study, it was 1.5%. As a result from this study, far offset, the smaller reduction of pile axial load and was appeared trend of settlement was similar among them. Particulary, ratio of pile load and settlement reduction were larger when the offset is from 0.5D to 1.0D than from 1.0D to 1.5D.

Utility of Large Scale Photogrammetric Techniques for 3-D Mapping and Precision Iron Ore Mining in Open Pit Areas

Precision mining and optimization of ore mining practise are gaining more importance as the global demand and competition for exploring the raw mineral material has grown manifold with increased industrialization world-wide. The overall process of mining activity involves ore identification, estimation, planning, excavation, transportation etc. The activity requires accurate mapping, monitoring and proper management of information pertaining to ore stockpile, mining pits and infrastructure of the areas on a regular basis. Of late, advancements in remote sensing techniques have paved a way for digital management of the mining activity. Especially, use of photogrammetric techniques for open pit mining are found to be highly accurate and effective in capturing, monitoring, mapping, managing the information pertaining to mining in a three dimensional (3D) space. Capturing of information pertaining to mines in 3-D perspective with respect to a specific location on the terrain is highly effective in accurate estimation of ore reserves, exploration and reclamation planning, ore continuity mapping and decision making. However, precision mining requires the use of large scale photogrammetric techniques with high resolution imagery of gigabytes size at mapping scales range from 1: 1000 to 1: 5000. In addition to that, the entire procedure involves the use of state-of-theart software and hardware for fast processing of data and subsequent digital output generation. Above all, involvement of skilled photogrammetric experts with specialised knowledge on open pit mining is very much essential for accurate interpretation and delineation of the resources. A project was carried out for the 3D mapping of iron ore stockpiles, pits and infrastructure areas at various sites. The stockpile and pit mapping is used for very precise volume measurements and the infrastructure mapping is used for general mine planning activities. High accuracy is critical, as the data and volume reports are used to calculate the value of the ore being extracted, and any errors in the mapping data can result in incorrect payments of large amounts of money. Since, the timeline specified to complete the task is very short, it is crucial that the staff doing the final volume computations and downstream processing should receive the accurate data, correctly coded and mapped according to the standards outlined. The study has demonstrated a typical workflow for the effective use of close range photogrammetric techniques for 3D mapping and iron ore mining in open pit areas. The study also sees a brighter outlook and challenges of upcoming aerial and terrestrial photogrammetric technology for precision mining.

TOWARDS A LOW-COST, REAL-TIME PHOTOGRAMMETRIC LANDSLIDE MONITORING SYSTEM UTILISING MOBILE AND CLOUD COMPUTING TECHNOLOGY

Close-range photogrammetric techniques offer a potentially low-cost approach in terms of implementation and operation for initial assessment and monitoring of landslide processes over small areas. In particular, the Structure-from-Motion (SfM) pipeline is now extensively used to help overcome many constraints of traditional digital photogrammetry, offering increased user-friendliness to nonexperts, as well as lower costs. However, a landslide monitoring approach based on the SfM technique also presents some potential drawbacks due to the difficulty in managing and processing a large volume of data in real-time. This research addresses the aforementioned issues by attempting to combine a mobile device with cloud computing technology to develop a photogrammetric measurement solution as part of a monitoring system for landslide hazard analysis. The research presented here focusses on (i) the development of an Android mobile application; (ii) the implementation of SfM-based open-source software in the Amazon cloud computing web service, and (iii) performance assessment through a simulated environment using data collected at a recognized landslide test site in North Yorkshire, UK. Whilst the landslide monitoring mobile application is under development, this paper describes experiments carried out to ensure effective performance of the system in the future. Investigations presented here describe the initial assessment of a cloud-implemented approach, which is developed around the well-known VisualSFM algorithm. Results are compared to point clouds obtained from alternative SfM 3D reconstruction approaches considering a commercial software solution (Agisoft PhotoScan) and a web-based system (Autodesk 123D Catch). Investigations demonstrate that the cloud-based photogrammetric measurement system is capable of providing results of centimeter-level accuracy, evidencing its potential to provide an effective approach for quantifying and analyzing landslide hazard at a local-scale.

TOWARDS A LOW-COST, REAL-TIME PHOTOGRAMMETRIC LANDSLIDE MONITORING SYSTEM UTILISING MOBILE AND CLOUD COMPUTING TECHNOLOGY

Abstract. Close-range photogrammetric techniques offer a potentially low-cost approach in terms of implementation and operation for initial assessment and monitoring of landslide processes over small areas. In particular, the Structure-from-Motion (SfM) pipeline is now extensively used to help overcome many constraints of traditional digital photogrammetry, offering increased user-friendliness to nonexperts, as well as lower costs. However, a landslide monitoring approach based on the SfM technique also presents some potential drawbacks due to the difficulty in managing and processing a large volume of data in real-time. This research addresses the aforementioned issues by attempting to combine a mobile device with cloud computing technology to develop a photogrammetric measurement solution as part of a monitoring system for landslide hazard analysis. The research presented here focusses on (i) the development of an Android mobile application; (ii) the implementation of SfM-based open-source software in the Amazon cloud computing web service, and (iii) performance assessment through a simulated environment using data collected at a recognized landslide test site in North Yorkshire, UK. Whilst the landslide monitoring mobile application is under development, this paper describes experiments carried out to ensure effective performance of the system in the future. Investigations presented here describe the initial assessment of a cloud-implemented approach, which is developed around the well-known VisualSFM algorithm. Results are compared to point clouds obtained from alternative SfM 3D reconstruction approaches considering a commercial software solution (Agisoft PhotoScan) and a web-based system (Autodesk 123D Catch). Investigations demonstrate that the cloud-based photogrammetric measurement system is capable of providing results of centimeter-level accuracy, evidencing its potential to provide an effective approach for quantifying and analyzing landslide hazard at a local-scale.

Digital close range photogrammetry for the study of rill development at flume scale

Soil erosion is a continuous process of detachment, transportation, and deposition of soil particles. Obtaining accurate descriptions of soil surface topography is crucial for quantifying changes to the soil surface during erosion processes. The objective of this study was to develop an improved close-range photogrammetric technique to assess soil erosion under rainfall conditions. Based on high overlapping image acquisition, digital point cloud matching, digital elevation model (DEM) generation and soil erosion calculation, a digital close-range photogrammetric observation system was explored and established. The results showed that the established digital photogrammetric observation system could accurately calculate the digital point cloud from the underlying surface with a 2min time interval and a 1.5mm spatial resolution. In addition, based on the DEM generated from digital point clouds, the amount of soil erosion in different topographic positions within various time periods was calculated. The digital photogrammetric observation methods explored in our study provide a reliable way to monitor soil erosion processes, especially under rainfall conditions. This approach can accurately resolve the evolution of the underlying surface soil erosion, which is of great importance in understanding soil erosion mechanisms.

Investigation of strain behaviour of soil surrounding the embedded wall by close range photogrammetry

This paper discusses strain behaviour of soil surrounding the embedded wall using the close range photogrammetric technique and finite element analysis k]The finite element analyses incorporated two forms of an interface element for the plane-strain analyses and it was found that the degree of non-associated flow was a dominant factor in terms of numerical solution convergence k]However k]a comparative study showed that the displacement and strain data from the finite element analysis was in good agreement with the model test using the photo imaging process.

Analysis of ground behavior for model tunnel excavation with pipe roof reinforcement using close range photogrammetric technique

혼잡한 도심지에서는 지상의 공간부족에 따른 터널 구조물에 대한 시공의 필요성이 늘어나고 있다. 터널은 굴착 시 주위 지반의 교란 및 변위를 발생시키는데, 그에 따른 안정성 검토가 필요하다. 따라서 본 연구에서는 터널굴착에 따른 지반의 거동을 측정하기 위해 모형터널 장비를 개발하였다. 모형터널은 터널굴착을 모사하기 위해서 터널 내부의 일정한 물의 양을 조절하면서 외경을 축소한다. 그에 따라 발생하는 체적손실이 터널굴착에 따른 지반의 변위를 발생시킨다. 지반의 변형 측정은 근거리 사진계측기법을 사용하였으며, 이를 변위분포도와 변위벡터로 나타내었고, 유한요소 수치해석, 기존 문헌, 이론 및 경험식들과 비교하였다. 또한, 터널 천단부 강관 보강 및 무보강의 터널굴착에 따른 모형시험을 진행하여 지반의 거동을 분석하였다. 본 연구의 실내모형터널시험은 지반의 자세한 변위 데이터를 얻기 위해 흙으로 가정한 알루미늄봉과 근거리 사진계측을 사용한 이상화된 2차원의 연구이다. 그 결과, 유한요소 수치해석에서의 흙의 변형 패턴이 실제 모형 시험과 상당히 유사함을 확인 및 검증 할 수 있었다. In congested urban areas, constructions of tunnel structures have became necessary due to a lack of surface space. The excavation of any tunnel generated the ground disturbances of surrounding ground and displacements is major concern. Therefore, a study of tunnel stability is necessary. In this study, the authors have investigated the stability and failure pattern of tunnel through the model tunnel test. In this study, the close range photogrammetry was used to measure the ground deformation. The measured data was converted to displacement vectors and contours. And then it compared to FE analysis and empirical formula. In addition, this study presented the comparison between steel pipe reinforced model tunnel and unreinforced model tunnel. The ground deformation for both the steel pipe reinforced model tunnel and the unreinforced model tunnel was analysed.

USING CLOSE RANGE PHOTOGRAMMETRY TO MEASURE THE POSITION OF INACCESSIBLE GEOLOGICAL FEATURES

In this study, the tectonic Timras doline geological maps were successfully obtained using digital close range photogrammetric techniques. This method is more reliable, faster, more accurate, and much safer. Accurate dimensions of different aspects including depth, width, slope, cracks, and various kinds of required details can be measured and used as geological inputs to obtain 3D geological maps. Furthermore, many dangerous places cannot be accurately measured by classical methods and photogrammetric methods can be safely used in these situations. Nowadays, generally, digital close range photogrammetry is applied due to cost advantages over conventional measurement techniques. First, taking photos is quite cheap and the labor costs are lower as well. In terrestrial measurement usually only two people are needed, because only the GCP have to be signalized and measured in the terrain by geodetic methods. Photogrammetric processing itself can be done by one person. The working time of the field study is also very short in comparison to other classical methods. In addition to these advantages, the 3D models which are obtained can be used for settlement planning. Furthermore, the models can provide information that enables the preservation of geological heritage and can contribute to the development of geotourism.

Monitoring of the reflectors of ESA's Planck telescope by close-range photogrammetry

The Planck mission of the European Space Agency (ESA) is designed to image the anisotropies of the Cosmic Background Radiation Field over the whole sky. Planck's objective is to analyze, with the highest accuracy ever achieved, the remnants of the radiation that filled the universe immediately after the Big Bang, which we observe today as the cosmic microwave background. To achieve this aim well-manufactured reflectors are used as parts of the Planck telescope receiving system. The system consists of the Secondary and Primary Reflectors which are sections of two different ellipsoids of revolution with diameters of 1.1 and 1.9 meters. Deformations of the reflectors which influence the optical parameters and the gain of receiving signals are investigated in vacuum and at temperatures down to 95K, using close-range photogrammetric techniques. We have designed an optimal close-range photogrammetric network by heuristic simulation for the Primary and Secondary Reflectors with a mean relative precision better than 1:1,000,000 and 1:400,000, respectively, to achieve the requested accuracies. Special considerations have been taken into account in different steps of design, such as the determinability of additional parameters under the given network configuration, datum definition, reliability and precision issues as well as workspace limits and propagating errors from different sources of errors. A least squares best-fit ellipsoid was developed to determine the optical parameters of the reflector. We present our procedure and the results of processing the photogrammetric measurements of the Flight Models of the Primary and Secondary Reflectors which were executed by Thales Alenia Space France under ESA-ESTEC contract in vacuum and at very low temperatures.

A model test and numerical investigation on the shear deformation patterns of deep wall–soil–tunnel interaction

In congested urban areas, tunnel excavations have become necessary due to a lack of space. In many cases, such excavations are needed in areas adjacent to existing loaded piles. Therefore, a careful assessment of the wall–soil–tunnel interaction is required. These circumstances are relatively new, however, and only limited information is currently available. The complicated soil behaviour, particularly for the shear failure pattern between the wall and tunnel observed in both physical tests and numerical analyses, has not been clearly identified by other researchers. The authors have conducted laboratory model tests on an idealized granular medium using close-range photogrammetric techniques to measure detailed displacement patterns. The results have been compared with those from numerical analyses. This paper presents shear failure patterns for a number of geometries and shows good agreement between the physical tests and the finite element analyses.Key words: tunnel excavation, shear deformation patterns, wall–soil–tunnel interaction, model tests, photogrammetry, finite element analysis.