鲁西南某2300MW坑口电厂桩基原位试验研究

鲁西南某2300MW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2300MW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CAPWAP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。

IN-SITU TESTS OF PILE FOUNDATION AT POWER PLANT IN SOUTHWEST OF SHANDONG PROVINCE

the foundation of a 2300MW pithead's power plant in southwest of Shandong province is located in alluvial layers of the Yellow River. The engineering properties of the strata are poor. The low foundation strength can't meet the needs of the key structures and buildings of the power plant. According to the geological conditions, foundation treatment has been conducted by high-strength pre-stressed concrete pipe. In the case study, we test the pile body with low strain integrity testing methods, determine the vertical ultimate bearing capacity of single pile using two methods such as high strain tests and static load tests, and contrast the advantages/disadvantages and affecting factors. Then we conclude the following three results.(1)Testing results by high strain CAPWAP method after fitting agree well with that by the vertical static load of a single pile. So it is likely to enhance the accuracy and reliability of high strain test results by optimizing the pile and soil parameters.(2)When it is not allowed for in-situ static load test, high strain tests can be used as a supplement means to the load test for pile foundation.(3)When we get more reliable high strain test results, some adjustments can be made for the design scheme according to standard method based on rigorous calculation.