Discussion on vertical bearing capacity of soft rock socketed pile in Chongqing area
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摘要: 结合某高层建筑软质岩嵌岩桩工程实例,对岩石单轴抗压强度试验、原位平板载荷试验、单桩静载荷试验3种方法确定的单桩竖向承载力结果进行对比分析。结果表明:平板载荷试验法确定的单桩竖向极限承载力标准值是岩石单轴抗压强度法的1.51倍,根据现行地方标准安全系数K的取值,平板载荷试验确定的单桩承载力特征值并未有所提高;单桩静载荷法得到的单桩承载力特征值是岩石单轴抗压强度法的3.12倍。根据分析结果,岩石单轴抗压强度法确定的单桩承载力偏于保守,建议考虑围压约束效应的影响;当采用岩基载荷试验法计算时,建议对重庆地方标准安全系数K的取值进行调整。Abstract: Combined with the engineering example of soft rock socketed pile in a high-rise building, the vertical bearing capacity of a single pile determined by rock uniaxial compressive strength test, in-situ plate load test, and single pile static load test was compared and analyzed. The results show that the standard value of the vertical ultimate bearing capacity of a single pile determined by the plate load test method is 1.51 times that of the rock uniaxial compressive strength method. According to the current local standard safety factor K, the characteristic value of the bearing capacity of a single pile determined by the plate load test has not been improved; The characteristic value of single pile bearing capacity obtained by the single pile static load method is 3.12 times that obtained by the rock uniaxial compressive strength method. According to the analysis results, the bearing capacity of a single pile determined by the rock uniaxial compressive strength method is conservative, and it is suggested to consider the influence of the confining pressure constraint effect. When the rock foundation load test method is used for calculation, it is suggested to adjust the value of the Chongqing local standard safety factor K.
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表 1 三种单桩竖向承载力确定方法比较
承载力确定
方法单桩极限
承载力
标准值/kN与方法一的
比值(标准值)单桩承载力
特征值/
kN与方法一
的比值
(特征值)单轴抗压强度法
(方法一)3931 1.00 1966 1.00 岩基载荷试验法
(方法二)5946 1.51 1982 1.01 单桩静载荷试验法
(方法三)12266 3.12 6133 3.12 -
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