Abstract
During the long-term service life of hydraulic structures, the calcium compounds in cement-based materials decompose in the aqueous environment, leading to the continuous change of seepage characteristics. To study the influence of calcium leaching on the concrete dam seepage characteristics, we proposed a new mathematic model of the cement-based material calcium leaching model under advection-diffusion-driven leaching. A solid-liquid nonequilibrium model is adopted to model the decomposition of calcium hydroxide (CH) and calcium silicate hydrate gel (C-S-H). To calculate the porosity more accurately, the proposed model takes the effect of different calcium compound decomposition on the porosity increase in consideration, respectively. Shimantan dam is selected for the three-dimensional (3D) calcium leaching analyses. The 3D finite element model of this dam is analyzed using COMSOL Multiphysics software that is based on the finite element method. Based on the proposed model, seepage characteristics evolutions of the Shimantan dam are studied. Good agreement between the numerical results and the monitored data indicates the accuracy of this simulation. The result shows that after 100 a leaching duration, the uplift pressure increases by 40.8%, and the leakage quantities of the dam body and foundation increase by 48 and 17 times. The rise of uplift pressure and leakage changes caused by curtain deterioration are the main influences of calcium leaching on the dam seepage. The parameter sensitivity results show that it is necessary to reduce CH content in cement-based materials to obtain better calcium leaching durability. This model and simulation results can guide the operation of concrete dams under advection-diffusion-driven leaching.
Highlights
Fengman concrete gravity dam was built in the year 1937. e impoundment started in the year 1942
The Pe numbers of two-grade concrete, three-grade concrete, normal concrete, and grout curtain are 115.5, 30.8, 117.0, and 71.7, and greater than 1 indicates that the calcium leaching in Shimantan concrete dam is advection-diffusion-driven leaching
We proposed a new mathematic model of hydrochemo behaviour of cement-based materials to investigate the concrete dam seepage characteristic evolution in the calcium leaching process. e proposed model had considered the effect of different calcium compounds decomposition on the porosity evolution
Summary
Fengman concrete gravity dam was built in the year 1937. e impoundment started in the year 1942. Fengman concrete gravity dam was built in the year 1937. E impoundment started in the year 1942. After nearly 80 years of operation, Fengman concrete gravity was demolished and rebuilt due to severe leakage and concrete deterioration problems. Calcium leaching is the foremost cause of leakage and concrete deterioration of Fengman dam [5]. Gutianxi flat slab buttress dam started to impound in the Advances in Civil Engineering year 1961. In 1990, there were four dam sections with serious leakage and seven dam sections with calcium leaching. In 2000, there were eight dam sections with serious leakage, twenty dam sections with calcium leaching. E overall strength of concrete slabs is decreased from 49.6 MPa to 37.9 MPa by 23.6% [6] In 2000, there were eight dam sections with serious leakage, twenty dam sections with calcium leaching. e overall strength of concrete slabs is decreased from 49.6 MPa to 37.9 MPa by 23.6% [6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
