深厚松散地层泄压槽治理井筒破坏判据及其与地下水水位关系

为了解决深厚松散地层预防性治理后竖井井筒缺乏破坏判据问题，用数值极限应变方法分析井筒应变值的变化情况，将井筒中达到极限应变值的单元环向贯通，计算不收敛作为井筒整体破坏判别标准。分别建立了带卸压槽和无卸压槽井筒的数值计算模型，得出地下水水位下降诱发的井筒和周围岩土体的极限应变值。结果表明，井筒周围砂土层先于井筒在181~183 m发生破坏：若地下水水位下降27 m，无泄压槽井筒在181~182 m发生破坏；若地下水水位下降38 m，带卸压槽井筒在182~183 m发生破坏。目前地下水水位下降为20 m，井筒处于安全状态。数值计算卸压槽压缩量与实际监测值一致。

Relationship Between Shaft Failure with Stress-Relief Groove and Groundwater Level in Thick Loose Strata

In order to solve the problem of failure criterion of concrete shafts in thick loose strata, the numerical limit strain method is used to analyze the change of shaft strain value,that is, when the strain of element circumferential connection reaches the limit strain value in the shaft, the calculation of non-convergence is taken as the criterion for the overall failure criterion of the shaft. In this study, two numerical calculation models of wellbore with and without pressure relief grooves were established respectively, as the stress-relief groove has a vertical pressure relief function. The calculations show that the soil around the shaft was destroyed before the shaft at 181-183 m. The shaft without stress-relief groove failed at 181-182 m when the groundwater level dropped by 27 m; While the shaft with stress-relief groove failed at 182-183 m when the groundwater level dropped by 38 m. At present, the groundwater level has dropped by 20 m, so the shaft is safe. The numerical ultimate calculation result is consistent with the actual monitoring value.