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地下流体的抽取所引起的地面沉降的预测依赖于所选理论模型中参数的量化。本文所建立的逆问题模型中涉及到压缩承压含水系统中5个控制地面沉降的参数:压缩弱透水层的垂向水力传导系数K’、塑性贮水率S’skv和弹性贮水率S’ske、含水层的贮水率S’S和弱透水层的前期最大固结压力p’max0。逆问题模型由Newton-Raphson调整算法和Helm有限差分一维固结模型构成(COMPAC),其中固结模型可用其他模型替代。文中用一个理想压缩承压含水系统对该逆问题模型进行检验,检验结果显示该模型能求解出理想压缩承压含水系统的K’、S’skv、S’ske、S’S和p’max0的近似值,其中p’max0和S’skv是控制计算沉降量的两个最主要的参数。每个监测点计算压缩量的平均相对误差为7.8%,该误差仅由调整算法产生。该逆问题模型应用于上海F9地面沉降监测点上部承压含水系统参数的求解和变形量的预测,所求解出的K’、S’skv、S’ske、S’S和p’max0的近似值分别为8.58×10-4 m/a、3.50×10-4 1/m、6.39×10-6 1/m、1.19×10-5 1/m和-2.50m、每个观测点计算压缩量的平均相对误差为13.7%。误差的来源除了调整算法外,还包括地下水位、压缩变形的观测误差以及模型概化所产生的误差。
Prediction of ground subsidence caused by the extraction of subsurface fluids relies on the quantification of parameters in the selected theoretical model. The inverse problem model established in this paper involves five parameters controlling ground subsidence in the compression-bearing aquifer: the vertical hydraulic conductivity K ’, the plastic storage S’skv and the elastic storage S ’ske, the water storage rate of the aquifer S’S, and the pre-consolidation maximum pressure p’max0 of the aquitard. The inverse problem model is composed of Newton-Raphson adjustment algorithm and Helm finite difference one-dimensional consolidation model (COMPAC). The consolidation model can be replaced by other models. The inverse problem model is verified by an ideal compressive pressure aquifer system. The test results show that this model can solve the approximate values of K ’, S’skv, S’ske, S’s and p’max0 of ideal compressive confined aquifer system , Where p’max0 and S’skv are the two most important parameters controlling the settlement. The average relative error of each compression point was 7.8%, which was only generated by the adjustment algorithm. The inverse problem model is applied to the solution of the pressure-bearing aquifer system in the upper F9 land subsidence monitoring point in Shanghai and the prediction of the deformation. The approximate values of K ’, S’skv, S’ske, S’S and p’max0 are 8.58 × 10-4 m / a, 3.50 × 10-4 1 / m, 6.39 × 10-6 1 / m, 1.19 × 10-5 1 / m and -2.50m, and calculate the average relative compression The error is 13.7%. In addition to adjusting the source of error sources, but also includes the groundwater table, the observation of compression deformation errors and model generalization of the error.