建筑机械开挖沟槽的稳定性研究

在建筑机械开挖市政管线的沟槽过程中,由于槽壁坍塌、挖掘机倾倒,造成人员伤亡和经济损失的工程事故日益增多。基于模拟挖掘机开挖沟槽的离心模型试验结果,建立沟槽槽壁许可破坏模式及速度场,利用极限分析上限法求解开挖深度上限解。根据槽壁破坏特点对开挖深度上限解表达式进行简化,并利用离心模型试验结果对开挖深度简化式进行了验证。利用沟槽坍塌时滑动土体的宽度表达式得到的挖掘机荷载影响区划分图,直观地给出挖掘机荷载的影响区和非影响区。当挖掘机荷载作用在非影响区时,挖掘机荷载对开挖深度不产生影响,利用开挖深度简化式计算的开挖深度等于无挖掘机荷载时的开挖深度;当挖掘机荷载作用在影响区时,挖掘机荷载对开挖深度产生影响,可利用开挖深度简化式计算开挖深度与无挖掘机荷载时的开挖深度之比。

Stability of trench excavation by construction machinery

There were many accidents in which the workers were killed and buried under collapsed trench when the construction machinery such as a drag shovel fell or toppled over the edge of the trench during excavation.According to the results of centrifuge model tests simulating the process of trench excavation,the failure mode of trench wall and its velocity field were established.Upper-bound solution of the excavation depth could be given by the upper-bound theory.According to the characteristics of failure shape of trench walls,the expression for the upper-bound excavation depth was simplified.The simplified expression for the upper-bound excavation depth was verified by the results of centrifuge model tests.The division of influence area of machinery load was given by the expression width of for sliding soil body,and the influence area and non-influence area were visually represented.When the machinery load acted on the non-influence area,there was no influence on excavation depth,and the excavation depth given by the simplified expression for the upper-bound solution equals to that of without machinery load.When the machinery load acted on the influence area,the excavation depth was affected by machinery load,and the ratio of the excavation depth to that of without machinery load could be given by the simplified expression for the upper-bound solution.