“低掺量水泥固化高含水率黏土”地基非破坏性受荷时沉降特性及可靠性研究

The purpose of this project is to predict settlement and evaluate reliability of the "Cement Stabilized Clay at High Water content" (HW-CSC) ground under non-destructive loading. To this end, a great quantity of "Triaxial Compression Tests" (TCT) will be conducted first. By analyzing the TCT database using statistical fitting methods, the uniform function relation of the "HW-CSC Sample Axial Compression Force-Deformation" (p-s) prior to yield under a certain confining pressure will be established. And the quantitative relations between parameters included in the function and relative proportions (water content and cement dosage), and confining pressure will be identified. Meanwhile, based on the scaled earth pressure test, an appropriate empirical formula for the "Scaled HW-CSC Ground Load-Settlement" (P-S) relationship with the specific curing age will be established. This will be contributive to propose the prediction approach of the settlement for the scaled HW-CSC ground with the specific curing age. This project will also study the influence of curing age on the p-s relationship, and establish one model to express the relation between early and target curing age "p-s relationship". Using this model a method will be presented for predicting the P-S relationship with target curing age through the p-s relationship with early curing age. Finally, through mastering the safety margin of the scaled HW-CSC ground under non-destructive loading from the perspective of settlement, one reliability assessment approach for the scaled HW-CSC ground under non-destructive loading will be proposed. Using this approach the safety status of the HW-CSC ground under non-destructive loading can be quickly judged only by measuring the HW-CSC ground settlement under non-destructive loading.

项目致力于对非破坏性荷载作用下“低掺量水泥固化高含水率黏土”（简称HW-CSC）地基进行沉降预测及可靠性评估。开展三轴压缩试验并对结果进行数据拟合,建立HW-CSC试样屈服前轴向压力-变形关系统一函数式，揭示式中各参数与组分比（含水量、水泥剂量）及围压之间的定量关系。结合缩尺土压力试验，建立缩尺HW-CSC场地特定龄期荷载-沉降关系经验公式，提出缩尺HW-CSC场地特定龄期沉降发展规律预测方法。研究养护时间对HW-CSC试样轴向压力-变形关系影响规律，厘清早期-目标龄期“轴向压力-变形”之间关系，提出由HW-CSC试样早期轴向压力-变形关系预测缩尺HW-CSC场地目标龄期荷载-沉降关系的方法。从沉降角度掌握缩尺HW-CSC场地非破坏性受荷时的安全裕度，提出缩尺HW-CSC场地非破坏性受荷时的可靠性评估方法。利用该评估方法，仅需根据HW-CSC场地非破坏性受荷时的沉降即可评判场地安全性。

采用低掺量水泥固化高含水率黏土（以下简称HW-CSC）作为围垦填料，能有效缓解填土资源紧张和疏浚淤泥弃置问题。加快推进HW-CSC工程应用，不仅要理清HW-CSC强度特性，还应掌握HW-CSC变形特征。为此，本项目开展了如下主要工作并得到相应结论：.（1）利用海泥制作HW-CSC试样测试不同配合比下HW-CSC试样的无侧限抗压强度。分析结果表明，HW-CSC试样强度随水泥质量分数的增大而增大，随含水率的增加而减小，但减小的速率逐渐变慢。HW-CSC极限应变随养护龄期的增加趋于集中分布。总体来看，HW-CSC极限应变分布集中于1.0%～2.5%。.（2）测定不同配合比下HW-CSC试样无侧限抗压强度，对HW-CSC试样应力-应变关系进行拟合。分析结果表明，HW-CSC的应力-应变特性均表现为单峰值函数，宜选用Extreme函数来描述HW-CSC试样应力-应变关系。.（3）开展三轴试验测定不同测试围压下HW-CSC试样的抗压强度，对HW-CSC试样应力-应变关系进行函数拟合，分析测试围压对HW-CSC试样应力-应变模型的影响。分析结果表明，宜选用Extreme函数来描述HW-CSC试样应力-应变关系；随着测试围压的增大，HW-CSC试样的极限应力逐渐增加，极限应变先增加后减少。.（4）用水泥-废砖细骨料双掺固化处理高含水率黏土（双掺固化土）的方法，通过室内试验测试不同配合比条件下双掺固化土的无侧限抗压强度。试验结果表明：掺入废砖细骨料能够提高高含水率黏土的强度，但也增大了双掺固化土的变异性；双掺固化土的破坏形态主要表现为塑性剪切破坏，双掺固化土韧性比一般水泥固化土好。