Gravity sensing for rail construction feasibility study

识别地下灾害是铁路建设中的一个关键问题。在施工过程中发现意想不到的功能可能会产生重大的成本和时间影响。同样，如果没有发现危险，在轨道使用期间可能会造成下沉和变形。地下灾害可能是人为的，如古老的矿坑或隧道，也可能是自然形成的天坑或岩溶，它们可能会随着时间的推移而形成。传统的现场勘测技术，如探地雷达、电磁和地震，被广泛用于现场勘测，但都有局限性。长期以来，重力传感一直被认为是一种能为现场勘测增加重大价值的测量方法。密度发生变化的任何地下特征都会产生重力变化。但到目前为止，商业上可行的传感系统一直缺乏。硅微重力已经花了七年时间研究和开发MEMS相对重力仪。地面原型系统已于2021年在国家地下基础设施成功测试，商业原型将于2023年第一季度末上市。该项目是一项可行性研究，旨在确定重力测量对GCRE的适用性，以及对更广泛的铁路建设行业的适用性。拟议的项目将首先与GCRE合作，识别工地潜在的地下危险，并就一系列情景达成一致。这将涉及确定危险的类型、深度、大小和密度与周围材料的关系。然后，这些数据将被用来对灾害将产生的重力异常进行正演模拟。然后，将对照SMG重力仪的预测灵敏度进行评估，以确定在现实世界情景中可以识别哪些危险。利用正演模拟，将开发一个重力站测量程序，以确定用于大面积危险探测的最佳测量站数据密度。这将证明SMG重力测量在高铁和更广泛的铁路行业进行现场测量的商业可行性。

Identifying subsurface hazards is a critical issue for railway construction. Finding unexpected features during construction can have major cost and time impacts. Similarly, if not identified hazards can cause subsidence and deformation during the life of the track. Subsurface hazards may be man-made such as old minings or tunnels or natural in the form of sinkholes or karsts which can form over time.Traditional site survey technologies such as ground penetrating radar, electro-magnetics and seismic are used extensively for site surveying but all have limitations. Gravity sensing has long been identified as a measurement which would add significant value to site surveys. Any subsurface feature that has a change in density will create a change in gravity. But until now a commercially viable sensing system has been lacking.Silicon Microgravity has spent seven years of research and development on MEMS relative gravimeters. A prototype surface system has been successfully tested at the National Buried Infrastructure Facility in 2021 and the commercial prototype will be available at the end of Q1 2023\. This Project is a feasibility study to determine the applicability of gravity surveying to GCRE but also to the wider rail construction industry.The proposed project will start by working with GCRE to identify potential subsurface hazards at the site and agreeing a set of scenarios. This will involve defining the type of the hazard, the depth, size, and density versus the surrounding material. This data will then be used to forward model the gravity anomaly that the hazard would create. This will then be evaluated versus the projected sensitivity of the SMG gravimeter to determine which hazards can be identified in a real-world scenario. Using the forward modelling, a gravity station survey program will be developed to determine optimal survey station data density for hazard detection over large areas. This will demonstrate the commercial viability of SMG gravity surveys for site surveys at GCRE and more broadly in the rail industry.