某水力枢纽基坑开挖过程渗流耦合数值模拟

岩土工程中存在多种耦合作用，在水利水电工程中，渗流场与应力场的耦合是最重要的。以某水利枢纽厂房基坑开挖为工程背景，比奥固结理论为理论基础，莫尔-库仑准则为土体屈服判据，对基坑开挖过程中渗流耦合进行了数值模拟。计算结果显示：回填后的应力略大于开挖过程中的应力，沉井附近出现一定程度的应力集中。回填前后塑性区变化不大且范围较小，因而土体的屈服破坏不是该工程的重点。由于土体渗透系数大，厂房区地下水位高，基坑开挖过程中渗水量较大，回填后沉井及基坑底部防渗底板的防渗效果显著，因而在基坑开挖过程中防渗排水是该工程的重点问题。

Numerical simulation of hydro-mechanical coupling for a hydraulic project pit in excavation process

There are many coupling effects in rock and soil engineering; seepage field and stress coupling is important in the water resources and hydropower engineering. Taking a hydraulic project foundation pit excavation as engineering background, Biot’s consolidation theory as theoretical basis, and Mohr-Coulomb’s principle as soil yield criterion, hydro-mechanical coupling of foundation pit is simulated in the process of excavation. The results indicate that the stress of backfill is larger than that of excavation, and there is a certain degree stress concentration near the open caisson. There is little yield region before and after backfill; so yield failure of soil is not a major problem in the engineering. Because of large coefficient of permeability of soil and high level of groundwater in the region of powerhouse, seepage discharge is very large in the process of excavation. Open caisson and impervious soleplate laid on the floor of the foundation pit have obvious effect on reducing seepage discharge. In conclusion, permeability-reducing and drainage are the key problem in the process of excavation of the engineering.