上海国土资源
上海國土資源
상해국토자원
2014年
4期
35~39
,共null页
地面沉降 含水层变形 水力梯度 剪应力 Cosserat力学理论 尺度效应
地麵沉降 含水層變形 水力梯度 剪應力 Cosserat力學理論 呎度效應
지면침강 함수층변형 수력제도 전응력 Cosserat역학이론 척도효응
land subsidence;deformation of aquifer;hydraulic gradient;shear stress;Cosserat continuum mechanics;scale effect
近年来上海及苏锡常地区的地面沉降出现了含水层砂土持续变形的新特征，现有的地面沉降理论无法完全解释与预测此现象。地下水长期开采会在含水层中形成水力漏斗，如果抽水井在一定范围内密集分布，就将在含水层中较长距离内形成水力梯度，从而产生无法忽视的剪应力，剪应力不断累积将导致含水层变形及地面沉降。含水层水位下降引起的土层中剪应力累积是造成含水层变形问题的重要原因，传统的Cauchy力学理论因为模拟单元较小，存在剪应力互等的假设而无法计算此部分剪应力；而Cosserat力学理论考虑了介质尺度的影响，可以计算连续体中的非对称剪应力分布，因而能够考虑由水位变化产生的剪应力引起的含水层变形。
近年來上海及囌錫常地區的地麵沉降齣現瞭含水層砂土持續變形的新特徵，現有的地麵沉降理論無法完全解釋與預測此現象。地下水長期開採會在含水層中形成水力漏鬥，如果抽水井在一定範圍內密集分佈，就將在含水層中較長距離內形成水力梯度，從而產生無法忽視的剪應力，剪應力不斷纍積將導緻含水層變形及地麵沉降。含水層水位下降引起的土層中剪應力纍積是造成含水層變形問題的重要原因，傳統的Cauchy力學理論因為模擬單元較小，存在剪應力互等的假設而無法計算此部分剪應力；而Cosserat力學理論攷慮瞭介質呎度的影響，可以計算連續體中的非對稱剪應力分佈，因而能夠攷慮由水位變化產生的剪應力引起的含水層變形。
근년래상해급소석상지구적지면침강출현료함수층사토지속변형적신특정，현유적지면침강이론무법완전해석여예측차현상。지하수장기개채회재함수층중형성수력루두，여과추수정재일정범위내밀집분포，취장재함수층중교장거리내형성수력제도，종이산생무법홀시적전응력，전응력불단루적장도치함수층변형급지면침강。함수층수위하강인기적토층중전응력루적시조성함수층변형문제적중요원인，전통적Cauchy역학이론인위모의단원교소，존재전응력호등적가설이무법계산차부분전응력；이Cosserat역학이론고필료개질척도적영향，가이계산련속체중적비대칭전응력분포，인이능구고필유수위변화산생적전응력인기적함수층변형。
The recent monitoring of land subsidence and soil deformation in the Shanghai and Suzhou-Wuxi-Changzhou regions indicated that aquifer sand can cause excessive deformation, which wil only occur at the yield condition. Current research cannot explain the factors that lead to the excessive deformation of aquifer sand under lower vertical stress. When groundwater is pumped from densely distributed wel s, a wide hydraulic funnel wil form. Then, a hydraulic gradient wil form in the aquifer that wil lead to shear stress in the aquifer sand. Accumulated shear stress wil result in the deformation of the aquifer, and especial y land subsidence. So, the accumulated shear stress due to the drawdown of the groundwater level is one of the important causes of aquifer deformation. Traditional Cauchy continuum mechanics cannot consider this shear stress due to the hypothesis of equal shear stress in the aquifer unit. Cosserat continuum mechanics can be used to analyze the deformation of aquifers due to the action of accumulated shear stress by considering the scale effect and the asymmetric distribution of shear stress in the aquifer unit.
