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    考虑多维时空特征的基坑开挖地表沉降神经网络模型

    Neural Network Model for Excavation-Induced Ground Surface Settlements Considering Multidimensional Spatiotemporal Features

    • 摘要: 基于数据驱动的机器学习方法已逐渐被应用于基坑开挖引起的地表沉降预测,然而目前的神经网络模型通常仅考虑单个监测点的时序信息,忽略了多监测点之间的空间相关性,导致监测信息开发利用程度不足.针对此问题,提出了一种可考虑监测数据多维时空特征的seq2seq-ConvLSTM2D神经网络模型,将基坑开挖引起的周围地表沉降转化为数字图像,实现基坑周围地表沉降的长时间、多位置预测.该模型结合二维卷积操作和长短期记忆神经网络(long short-term memory,LSTM),可利用基坑周边所有测点数据,充分挖掘数据的时空关联性;通过序列到序列(sequence-to-sequence,seq2seq)结构实现多天地表沉降预测,揭示输入和输出序列长度的影响;此外,考虑到实际监测数据普遍含有缺失值,建立距离权重K近邻模型进行缺失值填充.以浙江音乐学院地铁站基坑工程为例,验证了所提模型的有效性.研究结果表明:该模型预测基坑开挖地表沉降的决定系数(R2)、平均绝对误差(MAE)、均方误差(MSE)分别达到了0.96、0.71mm、0.90mm2,相较于LSTM、CNN-LSTM和ConvLSTM1D模型具有更高的预测准确度;该模型可预测未来多天的地表沉降,有利于决策者提前规划和调配资源,以便应对可能出现的工程问题.

       

      Abstract: Data-driven machine learning methods have gradually been applied to predict the excavation-induced ground surface settlements.However,the existing neural network models only consider the data at a single monitoring point and ignore the spatial correlation between multiple monitoring points.This study proposes a seq2seq-ConvLSTM2D neural network model to consider the multi-dimensional spatiotemporal features.The model transforms the excavation-induced ground surface settlements into digital images and achieves a long-term settlement prediction at multiple points.The model combines 2D convolutional operation and long short-term memory (LSTM) neural networks to use all the monitoring data around the excavation and to fully exploit the spatiotemporal features of the data.The settlement prediction for multiple days is provided based on a sequence-to-sequence (seq2seq) structure.The effects of input and output sequence lengths are then studied.As the actual monitoring data usually have missing values,a distance-weighted K-nearest neighbors (KNN) model is used to fill in the missing data.The proposed method is illustrated using the excavation project of Zhejiang Conservatory of Music Station.The results show that the determination coefficient (R2),mean absolute error (MAE),and mean squared error (MSE) for settlement predictions are 0.96,0.71mm,and 0.90mm2,respectively.The proposed model outperforms the LSTM,CNN-LSTM,and ConvLSTM1D models in terms of prediction accuracy.The proposed model can provide long-term predictions of excavation-induced settlement,which helps decision-makers better plan and allocate resources to deal with potential engineering problems.

       

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