叠加推算沉降误差分析
Error analysis of settlement predicted by accumulative prediction method
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摘要: 堤坝等荷载是分级施加的,地基多是成层的,因此实测的表面沉降–时间曲线是由各级荷载、各层土对应的沉降–时间曲线叠加而成的。理论分析、工程实例表明叠加的沉降–时间曲线通常不是双曲线或指数曲线,在此基础上提出了叠加推算沉降和分别推算沉降的概念。叠加推算沉降误差分析表明叠加推算沉降的误差不但与土层之间的β比值、各级荷载之间的时间间隔有关,而且受沉降推算拟合函数与实际是否相符的影响。β相同的地层可以作为同一层地基,沉降推算采用的拟合函数与实际不同时,分别推算也存在误差。叠加推算的沉降小于分别推算的沉降,通常小于实际沉降。为了减少沉降推算误差,建议尽量利用预压后期的监测数据,并尽可能采用分别推算沉降或采用修正的双曲线法或指数法等。 更多还原 AbstractFilter('ChDivSummary','ChDivSummaryMore','ChDivSummaryReset');Abstract: Since the stage construction is typical for embankments and the ground is usually in layers,the curve of the measured ground settlement-time is accumulated by the curves of settlement-time corresponding to different ground strata and embankment construction stages.The theoretical analysis and project examples show that the curve of the accumulated settlement-time is not usually exponential or hyperbolic.Based on the above,the accumulative prediction method and respective prediction method are put forward.It is proven by error analysis of settlement predicted by the accumulative prediction method that the error is influenced by the β ratio of strata,the time interval of loading stages and whether or not the employed function reflects the true situation.Different strata with equal β can be taken as the same stratum.If the function employed by the settlement prediction is not the same as the true one,the settlement predicted by the respective prediction method has errors too.The settlement predicted by the accumulative prediction method is less than that by the respective prediction method and usually less than the true settlement.To reduce the error of the predicted settlement and large starting time for the settlement prediction,the respective prediction method and improved exponential method or hyperbolic method are suggested.