Abstract：The uniform experimental study on the subsidence caused by dewatering of bottom aquifer under external fixed load，which is implemented on a self-designed dewatering experimental setup with high stress and water pressure，shows that the dewatering subsidence complies with exponential variation. Sandy soil with fine grains has more deformation than sandy soil with coarse grains. The compressibility modulus of the dewatering subsidence， ，is mainly determined by the character diameter of the sand， ，and the effective stress increment， . The value of increases with increasing of and . For the same soil sample，the value of is positively correlative to the value of . When is constant，if there is more fine particle，the value of and will be smaller and the value of dewatering subsidence bigger.
