从大自然的地震中保存人类的过去

土木工程师正在不断寻找无损的测量技术，这些技术可以帮助估计结构状况。Leica Geosystems的高清测量（HDS）或激光扫描满足了这一需求。

A joint research team comprised of members from UC Berkeley’s Structures Laboratory (a research lab specialising in full-scale structural testing and numerical analysis), Miyamoto International (an earthquake and structural engineering firm in the USA), Smart Scanning Solutions, LLC (a 3D scanning and modelling service provider in Uzbekistan) and BNZ (Leica Geosystems’ representative in Uzbekistan) has been deploying HDS reality management technology at heritage monuments along the historic Silk Road within Uzbekistan. Multiple monuments have been captured and analysed for earthquake susceptibility.

开始：自然下降的评估

As a representative example of the many heritage monuments, the Registan Square ensemble in Samarkand, Uzbekistan was selected. The ensemble includes the Ulugh Beg Madrasah, 1417-1420, the Sher-Dor Madrasah, 1619-1636, the Tilya-Kori Madrasah and Mosque, 1646-1660, and the 18th century Chorsu domed market.

Earthquakes, extreme seasonal temperatures, normal depreciation of the buildings and the economic crises of the 18th and 19th centuries have left the ensemble in a ruined condition. Structural repairs and straightening of the minarets had been conducted in 1923 and 1932; however, major restoration works were undertaken in recent years.

The ensemble was scanned from more than 70 stations with a Leica ScanStation. In addition to the global dimensions of all monuments located within the ensemble, the scans captured all details of the monuments: tile shape and dimensions, their overall locations in the monuments, any imperfections and the overall geometric shapes of the portals and facades. To achieve this level of detail in point density, all scans were conducted with a density of 2 mm by 2 mm.

扫描数据产生了极为有价值的结果，可用于决策中亚洲地震地区的纪念碑的进一步恢复策略。在从点云中生成有限元模型中，使用Leica Cyclone软件用于具有复杂几何形状的表面。

智能扫描解决方案首席执行官Liliya Myagkova说：“鉴于扫描仪的实现超高扫描速度的能力，我们能够快速收集对纪念碑进行彻底调查所需的数据。”“和Cyclone简单的注册使团队能够处理点云以进行快速分析。”

的点云的一个尖塔pro倾斜vided answers to questions regarding the amount of incline in the structure. Based on the analysis of the point cloud, an estimate of 4.6 per cent of inclination was obtained. The original taper of the minaret is estimated as 2.3 per cent.

New expeditions and monitoring by laser scans

The laser scanning expeditions were expanded into new cities. An extensive list of historic structures included many cities of Uzbekistan: Bukhara, Shakhrisybaz and Tashkent. In addition to that, more historic structures in Samarkand were scanned.

Shakhrisyabz is located in southern Uzbekistan approximately 80 km south of Samarkand, Uzbekistan. Once a major city of Central Asia, it is primarily known today as the birthplace of 14th century Turco-Mongol conqueror Timur. The scanned monument, the Kuk Gumbaz (Blue Dome) Mosque, is from the Timurid Dynasty era and it is on the UNESCO World Heritage List. The monument was built in 1437 and over the centuries has undergone several restorations and reinforcement efforts.

The historic monument was scanned from 13 stations with aLeica ScanStation C10。数据注册以旋风进行，对于最终注册中使用的所有扫描，误差不超过3 mm。纪念碑从外部，主厅内和楼梯内部进行扫描，门户和主结构之间有大裂缝。

“借助乌兹别克斯坦极端的大陆气候，研究团队需要确保它可以依靠这些工具。由于C10可以在-20至+50摄氏度的温度下工作，因此这是该项目的理想选择。” BNZ总监Brian Quigley说。“整个360°x 270°视场还确保扫描纪念碑的复杂表面将捕获所有功能，并使研究人员更简单。”

The monument’s point cloud was investigated for anomalies. The main portal was investigated for its inclination from a vertical plane passing through the bottom of both piers. The portal’s inclination increases from south to north with the maximum differential displacement of 0.6 m at the top north corner. To ensure this degree of inclination of the portal is not progressing, a periodic monitoring by laser scanning was recommended to be carried out. It was also advised to proceed with the installation of laser targets to increase accuracy of monitoring. The permanently installed targets provide a consistent comparison between point clouds collected at different times.

The geometry of the finite element model was generated from the point cloud. All major imperfections and existing reinforcements were included into the geometry of the model. Numerical modelling and subsequent analysis was conducted in specialist software SAP2000.

Since there is a very large variability in the material properties of masonry walls, material tests were conducted on a brick recovered from the site. The material properties were used within the software for accurate modelling.

在不同时间扫描尖塔，以检查倾斜度是否随着时间的推移而发展。第一个扫描是由扫描C10and the second point cloud was collected by the P-series ScanStation. The first scans were registered to the second scans in Cyclone. The inclinations are estimated as a vector at each elevation with directivity and value. The latter result uses the main advantage of the high-definition laser scanning that captures multiple points of the surface that cannot be obtained by other means.

Future research for more protection

测试项目赢得了乌兹别克斯坦当局处理遗产建筑的兴趣和合作。这为沿乌兹别克斯坦在撒马尔罕，布哈拉，塔什肯特和沙克里西亚布的活跃地震区域沿乌兹别克斯坦的额外遗产扫描提供了权限。

With HDS scanning combined with material testing, advanced calibrated models were produced, accounting for brick properties, current conditions, and previous structural reinforcements. Long-term monitoring is being strategised and conservation recommendations are being provided based on the research data, including the investigation of dampening devices at an active mosque with multiple structural concerns.

“Laser scanning helps us to capture structural anomalies of historical artefacts so we can help protect them for future generations,” said Amir Gilani, Miyamoto International, Manager of Earthquake Engineering Department. “Without this advanced technology, it would be challenging to get the as-found geometry of historic structures with accuracy of few millimetres that is essential for structural analysis.”

In recognition of the team’s effort and value of the collected data, the point clouds were accepted into the CyArk 500 Challenge database, an international effort to catalogue and archive endangered cultural heritage.