Which of the following is NOT a type of stress to consider in underground installations?

Chemical stress is not typically a primary concern in the context of underground installations. When considering the various stress factors that can affect underground structures or installations, environmental, mechanical, and thermal stresses are commonly acknowledged.

Environmental stress includes the effects of the surrounding geological materials, water levels, and soil characteristics, which can impact the integrity and functionality of underground installations. Mechanical stress pertains to the forces exerted on structures due to weight, movement of soil, and external loads applied on the infrastructure. Thermal stress is related to temperature variations that can induce expansion or contraction in materials, which may lead to structural issues over time.

While chemical stress can be pertinent in certain contexts, such as corrosion in pipes or the reaction of materials with surrounding chemical substances, it is less commonly classified as a fundamental type of stress when addressing the overarching categories relevant to the design and maintenance of underground systems. This differentiation helps to clarify why chemical stress is viewed as less critical in this specific scenario.