NEM与IEM耦合方法在地下工程中的应用研究

Study on Application of Coupling Method of NEM and IEM in Underground Engineering

针对纯自然单元法(NEM)在处理地下工程无限域或半无限域问题时需要人为确定边界条件而带来计算误差的问题,引入无限元(IEM)模拟无穷远处边界条件,与自然元相结合形成耦合分析方法,并基于Laplace插值编制了相应程序;通过深埋圆形隧洞算例分析表明,与纯自然单元法相比,耦合方法显著提高了计算精度,选取较小的分析区域就可得到令人满意的结果,使得在满足工程要求前提下,采用耦合方法可以节省计算工作量,从而进一步增强了自然单元法处理地下工程问题的能力.

Aiming at the defect that biggish calculation errors are inevitably produced due to artificial selection of finite computational domain and subjective setting of boundary conditions when solving infinite or half infinite domain problems such as tunnel and foundation pit in underground engineering using single natural element method（NEM）,a coupling analysis method of NEM and infinite element method（IEM）was developed.In this method,IEM was introduced to simulate the boundary condi- tions at infinitely distant position and NEM is used for simulating the region within boundary.The corresponding analysis program is compiled with the adoption of Laplace interpolation for NEM.An example of deeply buried circle tunnel is employed to test the correction and validation of the coupling analysis method.The results showed that compared with single NEM the calculation precision is manifestly improved and even for a relatively small computational domain,the calculation results meeting engineering requirements can still be obtained using the coupling method,which means less computational cost and more powerful capacity of solving underground engineering problems for the coupling method of NEM and IEM.