Geotechnical risk assessment for buried infrastructure in Regina

萨斯喀彻温省的里贾纳位于一个具有高容量变化能力的膨胀粘土矿床上。TransGas有限公司负责通过由本地粘土支撑的管道网络提供天然气（包括1160公里的管道和78180条服务）。膨胀土的交替移动严重影响了埋地基础设施系统。全市管道故障率在40-110次/年之间，年均65次。根据以往的经验，该公司已经认识到周期性土壤变形是影响里贾纳管道完整性的主要因素。从保守设计的常规做法（基于特定地点和特定时间的方法）出发，本研究提出了对体积变化问题的全面研究。局部的膨胀和收缩是由以下参数决定的：土壤性质（电导率、饱和度）；地被物（植被、路面）；气候条件（降水、蒸发）；水文条件（排水、池塘）。本研究的主要目的是开发里贾纳地埋基础设施管理的岩土风险评估方法。研究方法大致包括两个主要活动，即不确定性描述和危害估计。从学术界到公司的技术转让将以技术报告的形式进行，其中将包含作为最终用户交付的岩土风险评估方法。申请人亦将协助TransGas有限公司将新设计的方法融入日常工作。该项目将帮助TransGas Limited实现以下目标：(i)最大限度地减少泄漏调查的数量；（ii）优先考虑关键领域。新的风险评估方法（捕捉土壤、覆盖、气候和水文的影响）将有助于减少与城市天然气分配系统相关的岩土灾害、运营成本和社会不确定性。这项研究的结果将适用于里贾纳的其他地埋公用事业（供水和污水收集），也将对加拿大其他有类似问题的社区有用。

Regina, Saskatchewan is situated on an expansive clay deposit possessing high volume change capability. TransGas Limited is responsible for providing natural gas through a pipeline network (comprising 1160 km of mains and 78180 services) that is supported by the indigenous clay. Alternate shifting movement in the expansive soil has severely affected buried infrastructure systems. The pipe failure rate in the city ranges between 40-110/year with an annual average of 65. Based on past experience, the company has recognized the significance of periodic soil deformations as the main factor influencing pipeline integrity in Regina. Departing from routine practice of conservative design (based on site-specific and time-specific approaches), this research proposes a comprehensive investigation of the volume change problem. Locally, swelling and shrinkage is governed by the following parameters: soil properties (conductivity, saturation); ground cover (vegetation, pavement); climatic condition (precipitation, evaporation); and hydrologic condition (drainage, ponding). The main objective of this research is to develop a geotechnical risk assessment method for management of buried infrastructure in Regina. The research methodology broadly comprises two main activities, namely: description of uncertainty and estimation of hazard. The transfer of technology from academia to the company will be in the form of a technical report that will contain the geotechnical risk assessment method as the end-user deliverable. The applicant will also be available to assist TransGas Limited to integrate the newly devised method into routine practice. This project will help TransGas Limited to achieve the following: (i) minimize the number of leak surveys and (ii) prioritize critical areas of interest. The new risk assessment approach (which captures the effects of soil, cover, climate, and hydrology) will be beneficial in reducing the geotechnical hazards, operational costs, and social uncertainty associated with the natural gas distribution system in the city. The findings of this research will be applicable to other buried utilities (water supply and sewage collection) in Regina and will also be useful to other communities in Canada with similar issues.