【摘要】 1992年12月16日,宛田乡政府发生一不规则椭圆形地裂,长90m,宽75m。地裂引起房裂,殃及57家住户,波及建筑物3100多平方米。地裂主要由位于岩溶很发育的D₃,石灰岩之上的洪积粉质粘土或卵砾石层中的土粒被水流带走,产生管涌,形成土洞,在1992年大旱地下水位降低时,触发土洞群顶板塌落,土体质点位移变形而引起。更多还原

【Abstract】 Ground crack was first noticed on Sept. 16, 1992. The crack occurs approximately as an ellipse in shape around the local governmental building, with a total length of 260m, The width of cracks ranges from 2 to 8 mm. About 57 homes and 3100m2 buildings were influenced, including some public buildings. After site investigation and desk study, the authors discovered that the crack was caused by underground conduit flow. Boreholes revealed that 20-40 m alluvial-proluvium was underlying by extensive karstified D3r limestone. Conduit flows in limestone or near basal surface bring fine particles away from overlying alluvial-proluvium. Suffosion and soil caves occurred. Very little precipitation in 1992 caused groundwater level a great falling down and triggered the ceilings of soil caves loosed or collapsed. Further, stress and soil particles redistributed, and cracks occurred on ground. Also, the authors presented countermeasures.更多还原