Abstract
The calcium leaching effect inevitably increases the grout curtain hydraulic conductivity. It is diffucult to sample and obtain the leaching-related calculation parameters for deep-buried grout curtains. This study introduced the inversion method into the calcium leaching analysis to get proper leaching-related calculation parameters and accurate results. An inverse analysis model was proposed using the genetic algorithm (GA) and finite element analysis technology to solve the calcium leaching problems. The objective function is constructed using the hydraulic head and leakage quantity time-series measurements, which improves the uniqueness and reliability of the inverse results. The proposed method was applied to the inverse analysis of the hydraulic conductivity evolution of the grout curtain in a concrete dam foundation. The predicted water heads and leakage quantity are consistent with the monitored data, indicating the rationality of this simulation. The grout curtain hydraulic conductivity prediction in 100 years is also presented. The results illustrate the feasibility of the proposed method for determining leaching-related parameters and the hydraulic conductivity prediction in the leaching process.
Highlights
Academic Editors: Camelia PetrescuIn grouting projects, cement slurry is injected into rock fractures to improve the foundation engineering properties such as permeability, strength, and deformation resistance [1,2,3].Hydraulic conductivity is a crucial hydrologic parameter of the grout curtains and foundation rock
The hydraulic conductivity is generally not changed with time, while for the grout curtains and concrete face slabs, the hydraulic conductivity is constantly changed under the effect of calcium leaching [4]
Calcium leaching occurs when the calcium compounds in the cement matrix dissolve in a low pH or alkaline solution
Summary
Cement slurry is injected into rock fractures to improve the foundation engineering properties such as permeability, strength, and deformation resistance [1,2,3]. Hydraulic conductivity is a crucial hydrologic parameter of the grout curtains and foundation rock. The hydraulic conductivity is generally not changed with time, while for the grout curtains and concrete face slabs, the hydraulic conductivity is constantly changed under the effect of calcium leaching [4]. In the calcium leaching process, the decomposition of calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) significantly degrade the cement-based material engineering performance. The Fengman concrete gravity dam has been demolished and reconstructed for severe calcium leaching and leakage issues. After nearly 40 years of operation, the overall concrete slabs strength of the Gutianxi flat-slab buttress dam decreased from 49.6 MPa to 37.9 MPa, by 23.6% [6]
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