Analytical methods and controlling techniques for deformation and environmental influence of deep excavations in soft soils

It has become a challenge to accurately estimate and reasonably control excavation-induced deformations as well as consequent influences in soft soil areas with the increasing excavation scale and complexity of adjacent facilities. The analytical methods and controlling techniques for the excavation-induced deformations and their subsequent influences have been systematically investigated. The environmental protection grade and deformation controlling standard for the excavations in soft soils are proposed considering synthetically both safety and economy aspects, which provides a basis for protection of different types of facilities close to the excavations. Furthermore, a simplified analysis method is established, helping engineers to get a quick estimation of excavation-induced influences. A sophisticated analytical method considering small strain stiffness of soils is introduced, and a practical method to determine the parameters of small strain constitutive model is proposed, making it possible to evaluate the excavation-induced deformations properly in engineering practices. To tackle the difficulty of quantifying the impact of aquifer pumping, a computational method is proposed to determine the key hydrogeological parameters and to evaluate the pumping-induced deformations based on the field group well pumping tests. Moreover, various green, low-carbon and low-environment-impact controlling techniques are proposed, including preliminary and permanent combination techniques, digital micro-disturbance soil mixing piles, automatically force-compensating concrete struts, ultra-deep soil mixing walls etc. The proposed methods and techniques have been successfully applied in many excavations, promoting further development of fine evaluation methods for the excavation-induced deformations and active protection techniques for complex facilities in urban areas and proactive providing technical support for the development and utilization of underground space.