新沂地区处于郯庐断裂带转换段的关键部位,自20世纪70年代以来在新沂地区共发现地裂缝灾害点28处。这些地裂缝以群发的形式发育在南马陵山以西、沂河—骆马湖以东的区域内,地裂灾害影响区面积达100 km²。新沂地裂缝与地层结构、地震活动、地下水开采等因素有着千丝万缕的联系,对其研究形成了多种观点。利用实地调查与勘探手段,新近查明了新沂地裂缝的基本特征,它们具有走向一致性、纵向尖灭性、局部群发性等特点,且与邻近断裂(郯庐断裂带次级断裂F3)具有高度一致性,属于区域构造控制型地裂缝。以新沂地区地质构造为原型,构建了逆断层作用下地裂缝成生物理试验模型。试验结果表明,随着逆断层断距加大而依次呈剪裂段、离层段、弯裂段等发展过程。结合新沂地区“地堑-地垒-地堑”组合结构,新沂地裂缝的成因机制可概括为“跷跷板”构造模型,在构造应力、自重应力、地下水波动等作用下,下沉段受挤压,上升段因抬升而弯裂,从而形成地裂缝。研究新沂地区地裂缝,对揭示郯庐断裂带“北-中-南”段构造变化和“深-浅-表”部结构联系具有重要的指示意义。

The Xinyi area is located in a crucial transitional zone of the Tan-Lu Fault Zone. Since the 1970s, a total of 28 earth fissures have been discovered in this region. These fissures are mainly concentrated in the area west of Nanmaling Mountain and east of Yihe River-Luoma Lake, covering an affected area of approximately 100 km². The formation of Xinyi earth fissures is closely linked to the stratigraphic structure, seismic activity, and groundwater exploitation, leading to various perspectives on the subject. Recent on-site investigations and exploration methods have revealed the fundamental characteristics of Xinyi earth fissures, including consistent strike, longitudinal pinchout, and localized mass occurrence. These features align closely with the adjacent fault (secondary fault F3 of the Tan-Lu Fault Zone) and are classified as regional tectonic-type earth fissures. Drawing on the geological structure of the Xinyi area, a physical experimental model was developed to simulate the formation of earth fissures under reverse fault action. The experimental findings suggest that fissure development areas are delineated on the ground surface, progressing through stages of shear-cracking, separation, and “bending-cracking” with increasing fault displacement of the reverse fault. Considering the “graben-horst-graben” composite structure in the Xinyi area, the genesis of Xinyi earth fissures can be conceptualized as a seesaw-style tectonic model. Tectonic stress, gravity stress, groundwater fluctuations, among other factors, compress the subsidence section while causing bending and cracking in the rising section, ultimately resulting in the formation of earth fissures. The investigation of earth fissures in the Xinyi area holds significant importance in elucidating structural changes within the “north-middle-south” segment of the Tan-Lu Fault Zone and the interconnected “deep-shallow-surface” structural configurations.