粉质黏土地层基坑渣土免烧砖配比及力学性能研究

基坑开挖过程中会产生大量渣土，为降低基坑渣土堆积、外运等对城市环境的影响，有必要对基坑渣土进行免烧砖制作技术研究。依托杭州地铁10号线某工区，基于均匀试验方法，设计并开展以粉质黏土为主要原料、水泥为胶凝材料、细砂为级配增强材料制备渣土免烧砖的配比试验，通过对试验结果进行线性回归和单因素分析，探究各因素对试样耐水性和抗压强度的影响规律。研究结果表明： 采用粉质黏土地层基坑渣土制备的免烧砖，其软化系数随水泥和细砂占比增加而增大； 7 d抗压强度和28 d抗压强度随水泥占比增加而增大，随秸秆纤维占比增加而减小。在采用较优材料配比时，制得免烧砖软化系数大于0.8，7 d及28 d抗压强度均大于10 MPa，达到JC/T 422—2007《非烧结垃圾尾矿砖》MU10等级要求。

Study on Proportioning and Mechanical Properties of Unfired Bricks Based on Foundation Pit Muck in Silty Clay Stratum

In the excavation process of foundation pit, a large amount of muck is generated. In order to minimize the influence of muck accumulation and transportation generated by foundation pit excavation, the technology of manufacturing unfired bricks by foundation pit muck should be developed. Hence, the proportioning test on unfired bricks with silty clay as main raw material, cement as cementing material, and fine sand as grading reinforcing material is designed by uniform test method based on a test area of Hangzhou Metro Line 10. Through linear regression and single factor analysis of test results, the influence of various factors on the water resistance and compressive strength of the samples are investigated. The results show that: (1) The softening coefficient of unfired brick prepared by foundation pit muck in silty clay stratum increases with the rise of cement and fine sand proportion. (2) The 7 day and 28 day compressive strengths increase with the rise of cement proportion and decrease with the rise of straw fiber proportion. When the better material ratio is adopted, the softening coefficient of unfired bricks is greater than 0.8, the 7 day and 28 day compressive strengths are greater than 10 MPa.