真空联合堆载预压中孔压监测研究

在阐述孔压监测重要性的基础上,结合实际工程的监测数据分析了孔压的变化规律,并解释了其产生的原因,同时针对孔隙水压力计的埋设,提出了一些控制要点,为孔压监测的进一步研究提供参考。     

高强预压锚固技术抗拔力提升效应

提出了一种以大掺量膨胀锚固体作为锚固体的新型自膨胀高强预压锚固技术,阐明了其工作原理.研发了能消除CT伪影、获取极大膨胀应力(大于35 MPa)、精确定位扫描的高强预压锚固体系测试装置及方法,并结合分圈层定量CT图像解析技术,建立了以膨胀剂掺量及临空面距离为变量的CT值预测公式.对自膨胀锚固体及锚固体外土体进行了对比试验,以CT值、径向和环向膨胀应力、体应变为主要表征量,分别得到了其CT值随膨胀压力的线性变化规律、膨胀力径向和环向空间演化规律、体应变随圈层变化规律,定量阐明了锚固体外土体从内圈层到外圈层密实度呈线性降低,而大直径锚固体线性增加的力学机理;揭示了高强预压锚固体系中自膨胀作用引发的密实度和正应力的增大对锚固体抗拔力提升的贡献.     

Effect of thermo-mechanical and low-cycle preloading on the strength of carbon fiber-reinforced ceramic matrix composites

Fiber-reinforced ceramic matrix composites (CMCs) exhibit excellent thermo-mechanical properties including outstanding resistance against damage and fatigue. Some CMCs show occasionally even a strength enhancement after fatigue, often interpreted with relieve of internal stresses and interfacial degradation. This study reports the influence of low-cycle thermo-mechanical preloading on the bending and tensile strength of carbon fiber-reinforced silicon carbon (C/C-SiC). For this purpose two C/C-SiC materials with the same fiber architecture but different assumed internal stress states were subjected to single and cyclic mechanical preloads up to 90% of their ultimate strength level at room temperature and at 350 °C. Statistical evaluations of the experiments show that the ultimate strength values were surprisingly unchanged after preloading. The results are discussed regarding the thermal residual stresses (TRS).     

Effect of pressurization frequency and duration on the consolidation of a dredged soil using air booster vacuum preloading combined with prefabricated horizontal drains

The prefabricated horizontal drain (PHD) clogging problem often results in poor drainage and consolidation effects. To solve this problem, this paper adopts air booster vacuum preloading combined with PHDs to treat dredged soil. Laboratory model tests and microscopic tests are used to investigate the improvement effect of this method on dredged soil consolidation at different pressurization frequency and duration. The test results indicate that pressurization can effectively relieve clogging and improve the consolidation efficiency. The frequent pressurization is conducive to the consolidation at the same air-boost ratio, and the longer pressurization duration has an obvious promoting effect in the later stage of consolidation at the same pressurization frequency. Furthermore, pressurization can significantly alleviate the PHDs clogging problem has also been demonstrated from the micro perspective. These findings could provide an important reference for the treatment of dredged soil by air booster vacuum preloading combined with PHDs.