城区地表骤发性塌陷的孕灾链发育机制及其阻断对策

The frequent sudden collapse of urban surface may result in major property loss and personal injury, worse yet, this situation occurs random and without warning lead to serious fear at every moment. The project is mainly aimed at remodeling stratum involving earth-rock aggregate, building debris and industrial residue. The corresponding special experimental system is developed. According to plenty of model experiments of remodeling stratum, the developmental mechanism of chain of breed disaster for sudden collapse of urban surface is revealed, meanwhile, the boosting mechanism of excavation of underground works on the chain of breed disasters is also revealed. Based on the monitoring data of model experiment, the mode as well as the corresponding mechanical mechanism of sudden collapse is generalized. Combine the mechanical mechanism of various collapse modes, the limit theory and the mutation model, the limit and mutation analytical method of sudden collapse is built. Computational formula of stable critical thickness of overlying strata above the cavity is derived. The technique of fast field test of packing particle size grading, the composite functional material with the function of permeable filtering and the ability to intercept disintegrating things of filling body, and the enhancement technique of deflection ability of remodeling stratum is developed, and then, the complete interrupted technique of development process of chain of breed disaster for sudden collapse is constructed. This study may contain the disaster of sudden collapse of urban surface effectively, and alleviate this heavy worry of this kind of disaster by person.

频繁的城区地表骤发性塌陷不但让遭遇者导致重大财产损失甚至人身伤亡，而且其无预兆和随机性特征时时刻刻给人们带来严重的担忧。本项目以土石混合体、建筑废料及工业废渣三类填料的重塑地层为重点，利用研发的专门实验系统，通过大量的重塑地层模型实验，揭示城区地表骤发性塌陷孕灾链的发育机制及位于孕灾链链环上的地下工程开挖对于骤发性塌陷形成的促进机理。基于模型实验监测资料，概化出骤发性塌陷的模式及其相应的力学机制。将各类塌陷模式力学机制、极限理论及突变模型三者结合，建立骤发性塌陷的极限突变分析方法，并导出塌陷位置地表下空洞上覆地层稳定临界厚度的计算式。通过研发填料粒径级配现场快速测试技术、具有透滤水及填筑体崩解物拦截能力的复合功能材料及重塑地层弯沉能力增强技术，构建骤发性塌陷孕灾链发育进程阻断的完整技术对策。本项目的研究对于城区地表骤发性塌陷灾患的形成将起到有效的遏制作用，减轻人们对于这种灾患的忧虑。

城区地表骤发性塌陷给人们的日常生活甚至生命安全带来极大不安和危害。本项目围绕其发生机制及其预防技术对策展开研究。通过加压喷淋室内模型试验，观测到重塑地层在输、排水管损坏渗漏水的冲蚀作用下，随喷淋强度的增大其混合填筑料颗粒运移方式依次体现为接触型、跃移型、层移型及浮移型等形式。采用氯化钠模拟可溶物成分，渗透试验表明填筑料的渗透性能与可溶物含量有关，且渗透系数的稳定需要较长时间。通过开挖模型试验，获得了地下工程与输排水管道正交、斜交、平行及侧向等各种情况下，当地下工程穿越时管道的安全状态等级。考虑混合体颗粒级别、含水率、可溶性成分、渗流水位深浅、水位变化幅度及频率、地表形态及地层边界随水迁移颗粒逃逸出口个数等因素，分类设计并对各类完成了系列室内模型试验。试验观测得到地层中空腔在水流冲蚀作用下萌生后，边界扩张在时间上分为初始、发育及临界稳定等阶段，在空间上分为水下和水上两个部分。空洞最终临界稳定时体积的80%在水下扩张达成。扩张的基本形式体现为间歇阶梯式崩塌。地层中应力、孔隙水压力、变形及空洞尺寸扩张变化大体上同步响应。基于事故调查及室内模型试验结果，城区地表塌陷总体上可概化为直筒型塌陷和漏斗型塌陷两大类型,引入突变学中的尖点突变模型，建立了骤发性塌陷突变分析方法。基于杜布依模型，结合渗流临界坡降算法，导得了空洞临界稳定状态时的宽度计算式。基于极限平衡理论及浅埋地下工程压力算法，结合合理拱轴线模型，分别推导获得了直筒型及漏斗型塌陷前极限稳定时的上覆填筑体临界厚度表达式。所导出方法计算输出与试验结果相对误差约5.0%。基于便利实用原则，研发了具有滤水及增强抗弯沉能力功能的复合结构等城区塌陷孕灾链阻断技术。总体上，本项研究较好地获知了城区地表塌陷孕灾发育机制，形成了相应的配套处治对策。这将有效减少城区地表塌陷事故的发生，也为城镇开发及“一带一路”战略的顺利实施提供技术支持。