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鲁西南某2×300MW坑口电厂地基位于黄河冲积地层中,工程地质性质较差,地基强度不能满足电厂重要建(构)筑物的要求。根据现场的工程地质条件,施工中采用预应力高强混凝土管桩(PHC桩)进行地基处理。本文以鲁西南某2×300MW坑口电厂桩基检测工程为实例,首先采用低应变法对桩身质量进行了检测,然后采用高应变试验和静载试验2种方法确定了单桩竖向极限承载力,并对这2种方法的优点、缺点和影响因素进行了分析和对比。得出结论:(1)采用高应变CAP-WAP法拟合后的试验结果与单桩竖向静载荷试验结果基本吻合,通过选取合适的桩、土参数模型使高应变试验的结果准确可靠,是切实可行的。(2)在现场条件不允许开展静载试验时,高应变试验可作为静载试验的补充手段对桩基进行检测。(3)当能够获得可靠的高应变试验结果(与静载试验基本吻合)时,可以通过严谨计算对规范法设计方案进行一定程度的调整,以节约成本,但要慎重对待。
The groundwork of a 2 × 300MW pithead power plant located in the southwest of Shandong Province is located in the alluvial stratum of the Yellow River. The engineering geological properties are poor and the foundation strength can not meet the requirements of the important building (structure) of the power plant. According to the site engineering geological conditions, the construction of prestressed high-strength concrete pipe pile (PHC pile) for foundation treatment. In this paper, a 2 × 300MW Hang Hau power plant pile foundation testing project as an example, first of all, using low strain method to test the pile body quality, and then using two methods of high strain test and static load test to determine the vertical load limit of single pile The strengths, weaknesses and influencing factors of these two methods are analyzed and compared. The conclusions are as follows: (1) The results of fitting with high-strain CAP-WAP method are in good agreement with the results of vertical static load test of single pile. The results of high-strain test are accurate and reliable by selecting appropriate parameters of pile and soil parameters, Is feasible. (2) When the static load test is not allowed under field conditions, the high strain test can be used to supplement the static load test to test the pile foundation. (3) When the reliable high-strain test results (basically consistent with the static load test) can be obtained, the design of the normative method can be adjusted to a certain extent by rigorous calculation in order to save costs but be treated with caution.