填土沉降与管涵渗漏条件下高陡挡墙稳定性分析

Stability Analysis of High and Steep Retaining Wall under the Condition of Fill Settlement and Pipe Culvert Leakage

山地城镇建设经常在沟谷地段建造高陡挡墙,墙后填土的固结沉降易诱发地下管涵破损渗漏,在强降雨导致的高水压条件下会产生管涌破坏,进而威胁高陡挡墙的整体稳定,是较为典型的岩土灾害。以福州软件园某高陡挡墙渗漏与管涌灾害事件为例,首先采用地质雷达探测了扶壁式挡墙填土区的地层扰动和地下脱空特征,应用CCTV检测技术揭示了墙后填土区地下管涵的破损和堵塞规律,分析了台风“卢碧”强降雨期间扶壁式挡墙坡脚两次发生管涵泥沙管涌和挡土墙壁承压泄水的灾害现象,开展了旱季天然工况、雨季排水工况和台风暴雨工况条件下高陡挡墙稳定性分析,分析了填土沉降与管涵渗漏条件下高陡挡墙失稳破坏的机制,并对极端条件下高陡挡墙的稳定性进行了分析与预测。结果表明:旱季天然工况下该高陡挡墙拥有一定的安全储备,雨季排水工况下高陡挡墙安全储备逐渐降低,但仍满足规范的设计要求,而台风暴雨工况下其安全储备已低于规范的设计要求;在台风暴雨驱动下填土沉降—管涵渗漏—承压管涌破坏是该高陡挡墙失稳破坏的机制。该研究成果可为类似工程建设规划设计及长期运维管理提供参考。

High and steep retaining walls are often built in gully and valley areas during the construction of mountainous towns.The consolidation and settlemerrt of the soil behind the walls induces breakage and leakage of underground pipe culverts.Under high water pressure conditions caused by heavy rainfall,pipe surge damage can occur,which threatens the overall stability of the high and steep retaining walls and is a typical geotechnical disaster.Taking high steep retaining wall leakage and pipe surge disaster of Fuzhou Software Park as an example,the stratigraphic disturbance and subsurface dehollowing characteristics of the filling area of the counterfort retaining wall are detected by the geological radar,the law of the underground pipe culvert breakage and blockage of the filling area behind the wall is revealed through the application of CCTV detection technology,and the disaster phenomena of sediment pipe surge of pipe culvert and drainage of retaining wall occurring twice at the buttressed retaining wall slope during the heavy rainfall period of typhoon"Lupi"is analyzed.The stability of the high and steep retaining wall under the conditions of natural conditions in dry season,drainage conditions in rainy season and typhoon and rainstorm conditions is analyzed,and the mechanism of destabilization and failure of the high and steep retaining wall under the conditions of fill settlement and pipe culvert leakage is analyzed and the stability of the high and steep retaining wall under extreme conditions is predicted and analyzed.The results are as follows:the high and steep retaining wall has a certain safety reserve under natural conditions in the dry season,and the safety reserve gradually decreases under drainage conditions in the rainy season,but still meets the design requirements of the code;the safety reserve is lower than the design requirements of the code under typhoon and rainstorm conditions;the mechanism o£instability and failure of the high and steep retaining wall is driven by fill settlement-pipe culvert leakage-pressure pipe surge damage under typhoon and rainstorm conditions.The research results can provide reference for similar engineering construetion planning and design and long-term operation and maintenance management.