Use of 3D Laser Scanner for Rock Fractures Mapping

In the process of investigation, design and upgrading of rock slopes, the orientation and spacing of the structural discontinuities or joints in the rock mass are thoroughly mapped in the field so that any unstable blocks can be identified and stabilization measures designed. The orientation of the structural discontinuities is traditionally measured manually using geological compass placed directly at the exposed surfaces. Scaffolding is usually erected so that the geologist can physically access the exposed rock surface. A large number of measurements are usually required in order to obtain a statistical mean of the fracture orientation. With the ongoing advances of digital technology, 3D laser scanning technique can be used to replace direct physical access and large number of manual measurements can be completely eliminated. A prototype system is described in this paper that combines the non-contact measurement technologies of photogrammetric imaging and 3D laser scanning to create dimensionally accurate and pictorially correct 3 dimensional models and orthoimages of a rock fractures. By taking photographs from at least two different locations, lines of sight are mathematically intersected to produce the 3D coordinates of the key reference points in a rock face. Automatic 3D laser scanning unit is then used to produce the 3D coordinates of the entire rock surface. By overlapping the images rectified from photogrammetry technique with the coordinates from 3D laser scanning in an Autodesk 3D Studio Max environment, the coordinates of any objects in the photographs can be selected and their orientation such as dip angle and dip direction calculated automatically. A case study is presented to compare the orientations of fracture planes measured using geological compass and the orientations from the prototype system developed.published_or_final_versio

Monitoring Slope Failure at Kadoorie Agricultural Research Centre with a 3D Laser Scanner

A loosely compacted fill slope with an angle of 33° was constructed at the Kadoorie Agricultural Research Centre of The University of Hong Kong. The height and width were 4.75 m and 9 m respectively. It was constructed by end-tipping method and resulted in a loose state with an initial dry density of 70% of the maximum dry density. Two rows of grouted nails were installed at a grid of 1.5 m x 1.5 m at an inclination of 20° from the horizontal. The slope was brought to failure by subjecting it to surcharge at the slope crest in combination with induced rise in groundwater table and precipitation. Heavy instrumentation comprised in-place inclinometer, vibrating wire piezometers, vibrating wire extensometer, earth pressure cell, tensiometer and strain gauges along soil nails and they had been monitored throughout the test. Surface movement was monitored using a GPS system and a 3D laser scanner. This paper focuses on the use of 3D laser scanner in capturing the formation of cracks and surface movement during the failure. It is found that by overlapping the point clouds generated from the scanner at different time intervals, the surface movement of the slope can be accurately recorded without the need of physically accessing the slope surface. When the slope reaches failure, the use of laser scanning can safely and quickly record the movement and dimension of washout and cracks, providing advantages over conventional survey method. This study shows that the movement obtained from the scanner agrees very well with that from conventional inclinometer reading at the surface. The travel distance of the surcharge block can be easily measured and point cloud can be easily modeled into geometrical shape for further rendering.published_or_final_versio

Reclamation Ground Settlement Monitoring by Using GPS and Other Positioning Technologies at ShenZhen Airport.

Hong Kong is a small territory of about 1070 km2 . There is an ever-increasing demand for land to cope with her increasing development. Typical geology in Hong Kong under the seabed comprises a layer of soft marine deposit of variable thickness of up to 20 m, overlying alluvium, residual soil, decomposed rock and bedrock. However, the marine deposit is too soft to support any structures. Conventional reclamation practice in Hong Kong is to dredge the marine deposit, build the seawalls and fill the enclosed space by sand. This conventional approach has many shortcomings. A research project was undertaken by The University of Hong Kong to develop a vacuum preloading technique that is environmentally safe to improve the engineering properties of the thick layer of soft marine deposits so that they can be kept in place during land reclamation. As a result, the environmental problems relating to dredging can be completely eliminated. A vacuum preloading test near the Shenzhen Airport was carried out as part of a very large research program. Sub-surface field instrumentation comprised piezometers, inclinometers, extensometers and pressure cells to monitor the performance of the vacuum system and the physical changes of the marine deposit during vacuum preloading. Surface settlement was monitored using 3 units of high precision GPS equipment throughout the test for checking against the sub-surface monitored movement. It is necessary to use a fully automatic system like GPS for replacing conventional survey because the test was carried out over water, which was difficult to access and the test was carried out over a very long period of 4 months. This paper reports the use of GPS for reclamation ground settlement monitoring and demonstrates cm-level positioning results through experimental trials. The results also agree very well with the sub-surface settlement readings.published_or_final_versio

A review of landslide problems and mitigation measures in Chongqing and Hong Kong: Similarities and differences

The cities of Chongqing and Hong Kong are both located at hilly areas which are highly populated, with buildings and major highways located very close to slopes and earth-retaining structures. Landslides and rockfalls are very common in both cities, and large expenditures are being incurred by both Governments on the investigation, design and implementation of mitigation and preventive measures to reduce the likelihood of the loss of life and economic losses due to landslides. As a result of the collaborative studies and technical exchange programs between the University of Hong Kong and the Chongqing Jianzhu University, a more in-depth understanding of the landslide problem, methodology and mitigation measures in Chongqing and Hong Kong was achieved. The objective of this paper is therefore to: (1) highlight the similarities and differences of the slope safety problems which these cities have been facing and (2) present and compare the key technical approaches these two cities have been undertaken to reduce the risk of landslide and rockfalls, so that both cities could benefit from the experience and lesson learnt. Based on the review of literature and published case records, it is concluded that the city of Chongqing has to deal with natural hazards such as earthquake, river erosion and flooding more than that in Hong Kong, but both cities have been applying practical and latest technology to mitigating the landslide problem. It is recommended that the city of Chongqing should consider establishing a sustainable long-term landslide management plan and that the landslide prevention system being used in Hong Kong could be a good reference starting point. © 2004 Elsevier B.V. All rights reserved.postprin

Rock mass classification and tunnel support design in China

The Conference proceedings' website is located at http://www.tunnelcanada.ca/publications.php?date=2003This paper presents and discusses the two recently established rock mass classification systems in China, namely the Basic Quality (BQ) and Host Rock Rating (HRR) systems. The establishment of the BQ and HRR rock mass classification systems in China is based on huge amount of experiences gathered in the design stages and later verified in the construction of rock tunnels and underground structures in China. The BQ system was originally used for classification ...published_or_final_versio

Strengthening primary care: The role of clinical practice guidelines

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What do Hong Kong's family physicians think of clinical guidelines? - A questionnaire survey

Objective: To study the current use of and attitude towards clinical guidelines (CGs) among Hong Kong's family physicians, and to explore the attributes that may enhance implementation. Design: Postal questionnaire survey. Subjects: A questionnaire was posted to all 1427 members of the Hong Kong College of Family Physicians (HKCFP) in the period from March to July, 2010. Main outcome measures: Response to a questionnaire on the current usage of and attitude towards CGs, respondents' demographic data. Results: 617 completed questionnaires were received (response rate 43.2%). Ninety-one percent of respondents had used CGs in patient care and 85% had used them within a month. Sixty-three percent of respondents gave the internet as the first answer to the question of where they found the clinical guidelines. "Contradicting recommendations" was ranked highest as a barrier to guideline use (82%), followed by "CGs not tailored for individual patient's needs" (77%), and "mistrust guidelines sponsored by pharmaceutical companies" (75%). There was a very high degree of agreement on what constituted a good CG: evidence-based (99%), simple and easy to use (99%), applicable to the local population (99%) and the primary care setting (98%), regularly updated (98%) and with cost effective recommendations (93%). On strategies thought to be useful in promoting the use of CGs, 96% of respondents agreed on effective dissemination, 93% on a central system for adoption of CGs, 90% on involving primary care doctors in drafting CGs and 71% on providing financial incentives. Conclusion: Most respondents were using and supportive of CGs, and would like to have a central system for guideline adoption and effective dissemination. They wished to be more involved in the development process. They thought a good CG should be evidence-based, simple and easy to use and applicable in the local setting. Family physicians' views about CGs are important and relevant for Hong Kong's guideline development policy.published_or_final_versio

擋土墻填土邊坡水文響應過程分析:以賴屋山擋土墻填土邊坡為例

Several cracks were found to occur on the slope face of the Laiwushan retaining wall.In order to understand the mechanism of deformation and failure mechanism,automatic monitoring instruments,including piezometers,tensiometers,moisture probes and in-place inclinometers were installed at the top of fill slope.The following findings can be observed based on the monitoring data of piezometers,moisture probes and tensiometers:rainfall infiltration has little influence on the fluctuation of the groundwater table,possibly because the groundwater table was deep;the response of pore pressure and volumetric water content at various depths in the fill was delayed,depending on the soil depth.The rainwater can infiltrate into a depth of over 3m,and a perched water table can be observed at the depth of 3m,resulting in reduction in shear strength of soil and potential shallow failure. 深圳賴屋山的一擋墻表面出現數條裂縫,為了深入研究其變形破壞機制,在擋墻背后填土區布置自動監測儀器,主要包括滲壓計、張力計與水分計及固定式測斜儀。通過對滲壓計、張力計和水分計的監測數據分析表明:填土內地下水位埋深大,降雨對其影響小;土體中孔隙壓力和體積含水量對強降雨響應隨著埋深存在不同程度的滯后性,強降雨入滲深度大于3m,并且在3m處形成瞬態飽和地下水,抗剪強度降低,易于引起邊坡的淺層變形破壞

擋土墻填土邊坡水文響應過程分析:以賴屋山擋土墻填土邊坡為例

Several cracks were found to occur on the slope face of the Laiwushan retaining wall.In order to understand the mechanism of deformation and failure mechanism,automatic monitoring instruments,including piezometers,tensiometers,moisture probes and in-place inclinometers were installed at the top of fill slope.The following findings can be observed based on the monitoring data of piezometers,moisture probes and tensiometers:rainfall infiltration has little influence on the fluctuation of the groundwater table,possibly because the groundwater table was deep;the response of pore pressure and volumetric water content at various depths in the fill was delayed,depending on the soil depth.The rainwater can infiltrate into a depth of over 3m,and a perched water table can be observed at the depth of 3m,resulting in reduction in shear strength of soil and potential shallow failure. 深圳賴屋山的一擋墻表面出現數條裂縫,為了深入研究其變形破壞機制,在擋墻背后填土區布置自動監測儀器,主要包括滲壓計、張力計與水分計及固定式測斜儀。通過對滲壓計、張力計和水分計的監測數據分析表明:填土內地下水位埋深大,降雨對其影響小;土體中孔隙壓力和體積含水量對強降雨響應隨著埋深存在不同程度的滯后性,強降雨入滲深度大于3m,并且在3m處形成瞬態飽和地下水,抗剪強度降低,易于引起邊坡的淺層變形破壞

NF-κB p65 Subunit Is Modulated by Latent Transforming Growth Factor-β Binding Protein 2 (LTBP2) in Nasopharyngeal Carcinoma HONE1 and HK1 Cells

NF-kappa B is a well-characterized transcription factor, widely known as a key player in tumor-derived inflammation and cancer development. Herein, we present the functional and molecular relevance of the canonical NF-kappa B p65 subunit in nasopharyngeal carcinoma (NPC). Loss-and gain-of-function approaches were utilized to reveal the functional characteristics of p65 in propagating tumor growth, tumor-associated angiogenesis, and epithelial-to-mesenchymal transition in NPC cells. Extracellular inflammatory stimuli are critical factors that trigger the NF-kappa B p65 signaling; hence, we investigated the components of the tumor microenvironment that might potentially influence the p65 signaling pathway. This led to the identification of an extracellular matrix (ECM) protein that was previously reported as a candidate tumor suppressor in NPC. Our studies on the Latent Transforming Growth Factor-beta Binding Protein 2 (LTBP2) protein provides substantial evidence that it can modulate the p65 transcriptional activity. Re-expression of LTBP2 elicits tumor suppressive effects that parallel the inactivation of p65 in NPC cells. LTBP2 was able to reduce phosphorylation of p65 at Serine 536, inhibit nuclear localization of active phosphorylated p65, and impair the p65 DNA-binding ability. This results in a consequential down-regulation of p65-related gene expression. Therefore, the data suggest that the overall up-regulation of p65 expression and the loss of this candidate ECM tumor suppressor are milestone events contributing to NPC development.published_or_final_versio