Abstract Cement Sand and Gravel (CSG) is a low-cost, environment-friendly composite material mixed of unscreened aggregate, cement, fly ash and water, and its properties differ from ordinary concrete due to different aggregate characteristics. In order to investigate the effect of aggregate characteristics on the mechanical behavior of CSG, this paper used numerical simulation method to divide the CSG into aggregate unit, cement mortar unit and interface unit at the mesoscopic level and randomly generate aggregate, then used laboratory uniaxial compression test results to inverse the said mesoscopic component parameters, and finally verified the rationality of mesoscopic numerical simulation. Based on the inversed parameters, the numerical simulation test of different aggregate grading was carried out and analyzed. The results showed that: (1) From the perspective of macroscopic mechanical properties, as the sand ratio increased, the aggregate occupancy and the peak stress decreased; under the same aggregate occupancy (the same sand ratio), the stress peak became higher with the improvement of aggregate grading (aggregates of small particle size increased); (2) At the mesoscopic level, the crack of CSG usually appeared on the interface and around the aggregate; the smaller the sand ratio was, the higher the aggregate occupancy was, the more obvious the stress concentration was, and the earlier the cracking of the test piece was, but there were many aggregates, so the eventual failure time was delayed. These research results can provide theoretical basis for engineering design and construction.

中文翻译：

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基于细观材料参数反演的CSG宏观和细观力学行为研究

摘要 水泥砂砾(Cement Sand and Gravel,CSG)是一种由未筛分骨料、水泥、粉煤灰和水混合而成的低成本、环保型复合材料，由于骨料特性不同，其性能也不同于普通混凝土。为研究骨料特性对CSG力学行为的影响，本文采用数值模拟方法将CSG在细观层面分为骨料单元、水泥砂浆单元和界面单元，随机生成骨料，然后采用实验室单轴压缩试验结果对上述细观元件参数进行反演，最终验证了细观数值模拟的合理性。基于反演参数，对不同骨料级配进行数值模拟试验并进行分析。结果表明：(1)从宏观力学性能上看，随着砂比的增加，骨料占有率和峰值应力降低；在相同的骨料占有率（相同砂比）下，随着骨料级配的提高（小粒径骨料增加），应力峰值变高；(2)在细观层面，CSG的裂纹通常出现在界面和骨料周围；砂比越小，骨料占有率越高，应力集中越明显，试件开裂越早，但骨料较多，延迟了最终破坏的时间。这些研究成果可为工程设计和施工提供理论依据。总占有率和峰值应力下降；在相同的骨料占有率（相同砂比）下，随着骨料级配的提高（小粒径骨料增加），应力峰值变高；(2)在细观层面，CSG的裂纹通常出现在界面和骨料周围；砂比越小，骨料占有率越高，应力集中越明显，试件开裂越早，但骨料较多，延迟了最终破坏的时间。这些研究成果可为工程设计和施工提供理论依据。总占有率和峰值应力下降；在相同的骨料占有率（相同砂比）下，随着骨料级配的提高（小粒径骨料增加），应力峰值变高；(2)在细观层面，CSG的裂纹通常出现在界面和骨料周围；砂比越小，骨料占有率越高，应力集中越明显，试件开裂越早，但骨料较多，延迟了最终破坏的时间。这些研究成果可为工程设计和施工提供理论依据。应力峰值随着集料级配的提高而升高（小粒径集料增加）；(2)在细观层面，CSG的裂纹通常出现在界面和骨料周围；砂比越小，骨料占有率越高，应力集中越明显，试件开裂越早，但骨料较多，延迟了最终破坏的时间。这些研究成果可为工程设计和施工提供理论依据。应力峰值随着集料级配的提高而升高（小粒径集料增加）；(2)在细观层面，CSG的裂纹通常出现在界面和骨料周围；砂比越小，骨料占有率越高，应力集中越明显，试件开裂越早，但骨料较多，延迟了最终破坏的时间。这些研究成果可为工程设计和施工提供理论依据。且试件开裂越早，但聚集体较多，延迟了最终的失效时间。这些研究成果可为工程设计和施工提供理论依据。且试件开裂越早，但聚集体较多，延迟了最终的失效时间。这些研究成果可为工程设计和施工提供理论依据。