Research on the Prediction of Stability for the Excavated Slopes by Using Monitoring Systems

在挡土墙施工前，大多数边坡都进行了开挖。然而，一些边坡往往失去稳定性，发生边坡破坏。建筑工人经常死于从坍塌的斜坡上掉下来的泥土的袭击。在施工过程中，坠土事故发生率仅次于高处坠落、交通事故和施工机械事故。根据对219个边坡的调查结果，考虑在其中30个边坡上建立位移计监测系统，以确定边坡的稳定性。通过对边坡位移的测量，有6个位移计出现了位移。2台引伸计在1小时内位移超过4mm，并向施工人员发出了落土报警。0.4伸缩仪的安装对于工人的避难是有用的。据认为，长野县每年的此类施工数量达到一千，包括沿着城市道路和城镇道路的施工。在长野县，每年发生一到两次的工人坠落事故。用0.4倍伸长计提供有用的信息可能是合理的。通过对多个边坡的位移监测，表明该监测系统不仅对工人的避难，而且对施工的快速进行是有效的。此外，在一小时内以4 mm的位移发出警报是合理的。

Prior to construction of retaining walls, slopes are excavated in most of slopes. However, some slopes often lose their stability and slope failure occur. Construction workers were often died by an attack of earth fall from collapsed slopes. Accidents by earth fall are large in number next to falling from higher place, traffic accidents and accidents by construction equipments during construction work. As the results of investigation on 219 slopes in all,it was considered to set up monitoring system by the extensometers on 30 percents of the slopes in order to confirm stability of the slopes. According to the measurement of displacements on the slopes, 6 percents of the extensometers showed some displacements. 2 percents of the extensometers showed the displacements of more than 4mm in a hour and gave an alarm for an earth fall to the workers. 0.4 percents of the extensometers were useful for refuge of workers.It is considered that the number of such a construction work reaches to one thousand in a year in Nagano Prefecture including those along city roads and town roads. Worker's accidents by earth fall usually occur once or twice a year in Nagano Prefecture. It may be reasonable value that 0.4 percents of the extensometers gave useful information. As the results of displacement measurement at many slopes, it has been clear that the monitoring system is effective not only for refuge of workers but also for quick performance of construction work. Also, it is reasonable to give alarm with displacements of 4 mm in an hour.