硫氧镁水泥固化沿海风电场滩涂软土加固机理及微观特性分析

沿海风电场滩涂软土含水率高,压缩性大,必须对其加固才能进行风电基础施工。为研究硫氧镁水泥固化滩涂软土的加固机理及微观特性,开展了硫氧镁水泥复合固化剂加固滩涂软土的XRD试验以及不同初始含水量（w）、固化剂掺量（Wg）和龄期（T）下固化滩涂软土的扫描电镜（SEM）试验,利用图像处理技术研究固化滩涂软土微观孔隙、微观颗粒形态以及接触面积率（RCA）受Wg、w和T影响的规律。研究结果发现,固化滩涂软土主要由石英、5Mg（OH）₂·MgSO₄·7H₂O相（简称5·1·7相）、白云石、叶腊石、M-F-A-S凝胶相以及少许CaO和MgO构成,固化机理包括改性硫氧镁水泥的水解和水化反应、离子交换及填充作用和碳酸化作用,固化滩涂软土微观孔隙可分为凝胶、接触和骨架3种类型,固体颗粒呈叶片状、颗粒状和凝块状3种形态。微观结构参数（RCA）与宏观力学参数,即初始切线模量Ei和强度指标（c和φ）均随w的增加而减小,随着Wg和T的增加而增大。最后建立了固化滩涂软土的RCA与Ei、c、φ之间的函数关系。

MECHANISM OF MUDFLAT SOFT CLAY STABILIZED BY MAGNSIA OXYSULFATE CEMENT AND ANALYSIS ON ITS MICRO-BEHAVIOR FOR OFFSHORE WIND FARM

The mudflat soft clay with high soil moisture and low compression modulus should be enhanced before the practical foundation construction of offshore wind farm. To investigate the stabilized mechanism and micro behavior of mudflat soft clay solidified by the magnesia oxysulfate cement, the X-ray diffraction （XRD） tests were conducted to determine the micro-ingredients of the mudflat soft clay solidified by the magnesia oxysulfate cement composite curing agent. A series of scanning electron microscope （SEM） tests were conducted on the solidified soil with different soil moistures（w）, curing agent dosages （Wg） and ages （T）. Then, the effects of w and Wg and T on the micro-void, micro-morphology and the contact area ratio （RCA） of the solidified soil were investigated by using Image Processing. It was found that the solidified soil was mainly constitutive of quartz, 5·1·7 phase, dolomite, pyrophyllite, M-F-A-S phase and a little of CaO and MgO. The stabilization of solidified soil is mainly due to the hydration and hydrolysis reaction of the modified magnesia cement, ion exchange and filling effect and the carbonation. The solidified soil mainly covers three types of micro-void： gelling and contact and skeleton, and it also contain three types of solid particles： foliated, granulous and clotted. The smaller the initial soil moisture, the larger the amount of curing agent and the longer the age, the greater the RCA and the macro-physical parameters （initial tangent modulus, Ei, and shear strength parameters, c and φ）of the solidified soil. Finally, the functional relationships between Ei, c, φ and RCA were established.