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针对目前钻芯取样、标准贯入试验、荷载试验等水泥搅拌桩的检测方法试验要求高、试验时间长、测试费用高等诸多缺点,提出联合测定水泥土初期pH值与电导率的方式来判断其后期无侧限抗压强度与混合土性状的方法。以上海地区第④层黏性土为研究对象、以水泥掺量为变量,对加固土体的化学性质与其强度增长特性做了试验研究;探讨了pH值和电导率与水泥掺量、养护时间、后期强度之间的关系。试验结果表明,当水泥土初期的pH值和电导率大于分别为11.5和0.09 s/m的临界值时开始产生强度。在此之后强度随着pH值的增长而缓慢增加,但当pH达到11.8时,强度开始随着pH值的增长而迅速增加。电导率与强度变化关系的这些特征可以避免用水泥土初期pH值单一化学指标来判定其后期无侧限抗压强度带来的误差与风险。为判定上海地区黏性土水泥搅拌桩的强度提供试验依据。
Aiming at the shortcomings of the current drilling core sampling, standard penetration test, load test and other testing methods of cement mixing pile test, the test time is long, the cost of the test is high, and the method of joint determination of the initial pH and conductivity of the cement soil is proposed Late unconfined compressive strength and mixed soil properties of the method. Taking the fourth layer of cohesive soil in Shanghai as the research object, with the cement content as a variable, the chemical properties and strength growth characteristics of reinforced soil were studied. The effects of pH and conductivity on the cement content, curing time , The relationship between the late strength. The experimental results show that the strength starts to develop when the initial pH and conductivity of cement soil exceed the critical values of 11.5 and 0.09 s / m, respectively. After that, the intensity slowly increased with increasing pH, but when the pH reached 11.8, the intensity began to increase rapidly with increasing pH. These characteristics of the relationship between conductivity and strength change can avoid the error and risk brought by the unconfined compressive strength of the later stage by using the single chemical index of initial pH of cement soil. The experimental evidence was provided to determine the strength of clay mixing pile in Shanghai area.