江苏某市人工堆山坍塌机理分析

MECHANISM ANALYSIS OF HEAP HILL COLLAPSE IN URBAN AREA OF SOUTHERN JIANGSU

近年来,在城市建设中,堆山造景工程越来越多,且规模也越来越大。堆山造景工程多是利用工程弃土、建筑垃圾、生活垃圾等固体废弃物,填筑在不能用于城市工程建设的废弃土地上。这样既能使城市固体废弃物和废弃土地得到有效利用,又能很好地美化城市环境。因此,堆山工程逐渐成为城市建设中美化居住环境的一种新时尚。然而这些不适宜作为工程建设的废弃土地,地质条件一般较为复杂,且距其周围建筑物的距离很近,同时堆山造景工程往往荷载量和堆载面积很大,远不同于一般工程,如处理不当极易诱发一系列的城市环境岩土工程问题。例如苏南某市堆山工程,建设在软土地基上,设计高度54m,当堆到40m时,突然发生大规模垮塌事故,一度造成工程停滞,给周围道路及建筑造成安全隐患。本文通过相关试验和计算,对其堆山工程发生坍塌事故的原因进行了相关研究。分析认为该工程的地基处理采用砂井方法不能满足工程要求,由于填筑荷载达760kPa,大大超过地基承载力,造成地基不均匀沉降和失稳破坏,加之施工速度过快,无法使填土很好地固结,最终导致了填筑山体整体垮塌事故。通过对该堆山事故分析,初步认为在软土地基上进行堆山工程,要保证安全必需满足二个条件,第一地基承载力必须满足堆载要求,否则需结合荷载形式选择合理的地基处理方案;第二在施工时基础的沉降特别是沉降差应控制在一定范围。

In recent years,man-made heap hills have become more and more for landscape of urban construction in Jiangsu plain area.Their sizes are growing larger and larger.The heap hills are usually made of engineering spoils,building refuses,garbage and other materials.They are built in wasteland that cannot be used for urban construction.The heap hills not only efficiently use solid waste and waste land,but also beautify very well the urban environment.They are a new fashion in urban construction.However,geological conditions of the waste land are gen-erally complex.It is very close from the surrounding buildings.A heap hill often has a high capacity and occupies a large load area.They are far different from the general engineering projects.If the engineering measures are unrea-sonable,some environmental geotechnical problems shall be induced easily.For example,a heap hill project was built on soft ground in urban area of southern Jiangsu Province.The design height of this hill is 54meters.The heap hill suddenly collapsed to large-scale when it was filled up to 40meters.This project stopped once.It posed risks to the surrounding roads and buildings.In this paper,with the tests and calculations,the collapse accident of the heap hill is studied in detail.The results indicate that the safety conditions of the heap hill in the soft soil foundation are as follows.The first,the bearing capacity of foundation must meet the requirements.The second,the foundation set-tlement,especially the discrepancy settlement,should be controlled within a certain range.