衬砌管片破损诱发无水砂卵石层塌陷试验研究

Experimental Research on the Subsidence of Anhydrous Sand Pebble Layer Induced by Lining Segment Damage

研究目的:为探求地下水位以上砂卵石层中隧道衬砌破损漏砂诱发的地层塌陷问题,本文通过自行设计的一套可以控制圆形漏口大小的地下工程漏砂可视化试验装置,分别试验研究卵石颗粒含量、土层厚度等影响因素对于地层塌陷、溃砂的影响规律,得到不同工况下土层的塌陷影响范围、沉降剖立面形态曲线,从而对溃砂灾害中的砂土运移规律和成拱机理进行探究。研究结论:(1)当厚跨比大于11.1时,土层不发生塌陷,当厚跨比大于4小于11.1,卵石颗粒含量大于临界卵石颗粒含量时,土层仅发生塌陷但不溃砂,小于该数值后,土层会发生溃砂,当厚跨比小于4时,无论卵石颗粒含量多大,土体均发生溃砂;(2)溃砂过程可大致分为四个阶段:初始阶段、贯通阶段、扩径阶段和稳定阶段;(3)固定卵石颗粒含量、漏口直径的情况下,塌陷影响范围和塌陷中心深度随土层厚度的增大而增大;圆形漏口诱发的塌陷在平面上呈圆形,剖面上近似呈二次曲线,立面上近似呈漏斗形;(4)土体溃砂后的塌陷范围与形状破坏角有关,破坏角比土体天然休止角大18°;(5)本文研究结果可为同类隧道工程的灾害治理及预防提供借鉴和参考。

Research purposes: In order to explore the formation collapse caused by tunnel lining damage and sand leakage in the sand gravel layer above the groundwater level, this paper studies the influence law of influencing factors such as pebble particle content and soil thickness on formation collapse and sand burst disaster through a set of self-designed visual test device for underground engineering sand leakage which can control the size of circular leakage, and obtains the influence range of soil collapse and the vertical shape curve of settlement profile under different working conditions, so as to explore the sand migration law and arching mechanism in the sand burst disaster.Research conclusions:(1) The test results show that when the thickness span ratio is greater than 11.1, the soil does not collapse. When the thickness span ratio is greater than 4 and less than 11.1, and the pebble particle content is greater than the critical pebble particle content, the soil only collapses but does not collapse. When the thickness span ratio is less than this value, the soil will collapse. When the thickness span ratio is less than 4, the soil will collapse regardless of the pebble particle content.(2) The sand breaking process can be roughly divided into four stages: initial stage, penetration stage, diameter expansion stage and stability stage.(3) Under the condition of fixed pebble content and leakage diameter, the influence range of collapse and the depth of collapse center increase with the increase of soil thickness;The collapse induced by circular leakage is circular on the plane, approximately conic on the section and funnel-shaped on the facade.(4) The collapse range of soil after sand break is related to the shape failure angle of the failure surface, which is 18° larger than the natural repose angle of soil.(5) The research results of this paper can provide guidance for disaster control and prevention of similar tunnel projects.